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000
FXUS63 KLOT 311141
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
641 AM CDT THU JUL 31 2014

.DISCUSSION...
257 AM CDT

SYNOPSIS...ROUNDS OF AFTERNOON SHOWERS AND THUNDERSTORMS WILL
CONTINUE THROUGH THE END OF THE WEEK.  MINIMAL CHANCES OF THUNDER
TODAY...BUT HIGHER CHANCES LOOK TO ARRIVE TOMORROW AND SATURDAY.
TEMPERATURES REMAIN AROUND 80 THROUGH THE WEEKEND EXCEPT FOR ALONG
THE LAKE WHERE LAKE BREEZES WILL KEEP HIGHS IN THE 70S TOMORROW
THROUGH THE WEEKEND. A BRIEF WARM UP INTO THE MID 80S IS EXPECTED
EARLY NEXT WEEK.

TODAY AND TONIGHT...
PREPARE FOR A VERY FAMILIAR SONG AND DANCE...BROAD HIGH PRESSURE IS
OVER THE REGION WITH LIGHT FLOW AND PATCHY FOG. THE FOG WILL BURN
OFF QUICKLY THIS MORNING AS MIXING GETS GOING. LOOKING AT A BREEZY
DAY WITH WEST WINDS AT 10-15 KT. A LAKE BREEZE WILL FORM...BUT
EXPECTING IT TO STAY JUST OFF SHORE AS WIND SPEEDS ARE AT 10+ KT
THROUGH THE COLUMN.

AN UPPER LEVEL VORT STREAMER APPROACHES FROM THE NORTHWEST TODAY.
THEREFORE...WEAK FORCING WILL BE OVER NORTHERN IL AND FAR NORTHERN
IN...SO HAVE ANOTHER ROUND OF ISOLATED TO SCATTERED SHOWERS IN THE
FORECAST. BASED ON YESTERDAYS LIMITED ACTIVITY...THINKING WE WILL
SEE FEW IF ANY THUNDERSTORMS. THE DVN SOUNDING FEATURED A CAP
AROUND 650MB YESTERDAY AND MODEL GUIDANCE HAS A SIMILAR CAP IN
STORE FOR US TODAY. THE BEST CHANCE FOR SHOWERS WILL BE NORTH OF
I-80. NOT EXPECTING MUCH PRECIP FROM ANY SHOWERS THAT DO FORM.

HIGH TEMPS WILL BE AROUND 80 AND OVERNIGHT LOWS WILL BE AROUND
60...EXCEPT FOR THE MID 60S DOWNTOWN. MAY SEE FOG AGAIN TOMORROW
NIGHT...BUT NOT OVERLY IMPRESSED SO LEFT FOG OUT OF THE FORECAST FOR
NOW.

JEE

FRIDAY...
THE UPPER PATTERN REMAINS THE SAME FOR ONE MORE DAY INTO FRIDAY WITH
THE FORECAST AREA REMAINING ON THE SOUTHWEST SIDE OF THE EASTERN
CANADIAN LONG WAVE TROUGH. ONE OR TWO SHORT WAVE IMPULSES ARE
PROJECTED TO MOVE AROUND THE TROUGH IN THE NORTHWEST FLOW ALOFT
DURING THE DAY AND EVENING ON FRIDAY...KEEPING 500MB AND 700MB
TEMPERATURES AT ONE TO TWO STANDARDIZED ANOMALIES BELOW NORMAL.
COMBINED WITH A LITTLE MORE LOW-LEVEL HEATING ON FRIDAY...THE
SLIGHT WARM TEMPERATURE NOSE/CAP NEAR 650MB YESTERDAY AND TODAY IS
EXPECTED TO BE OVERCOME BY THIS AND THUS FORECAST SOUNDINGS
PROVIDE 800 TO 1300 J/KG OF MLCAPE OVER SOUTHERN WI/NORTHERN IL
DESPITE FORECAST DEW POINTS ONLY IN THE UPPER 50S. OVERALL
COVERAGE OF STORMS IS EXPECTED TO BE HIGHER IN THE REGION THAN THE
PAST COUPLE DAYS BECAUSE OF THIS...MAYBE SIMILAR TO TUESDAY. A
FEW STRONGER UPDRAFTS AND ASSOCIATED GUSTY DOWNDRAFTS ARE POSSIBLE
IN THE REGION DURING MID- AFTERNOON THROUGH MID-EVE.

THIS WEEKEND...
HIGH PRESSURE...ALBEIT WEAK...IS FORECAST TO BUILD SOUTHEASTWARD
ACROSS THE REGION EARLY IN THE WEEKEND IN ASSOCIATION WITH HEIGHT
RISES ALOFT. A DEVELOPING WEAK COOL FRONT AHEAD OF THE HIGH LOOKS
TO BE A MODEST FOCUS FOR SCATTERED AFTERNOON SHOWERS/STORMS IN THE
LOWER GREAT LAKES REGION. THIS COULD BE PRIMARILY EAST OF THE
LOCAL AREA BASED ON SOME GUIDANCE...BUT GIVEN THE MODEL SPREAD AND
THE SUBTLE FEATURES THAT COULD SPARK SOME SHOWERS...FELT PRUDENT
TO KEEP CHANCE POPS DURING THE DAY. NORTHEAST FLOW IS ANTICIPATED
TO DEVELOP AND DEPENDING ON TIMING COULD PROVIDE A STRONGER LAKE
BREEZE WITH AFTERNOON COOLING IN LAKE ADJACENT COUNTIES. THE HIGH
LOOKS TO MAKE FOR A PLEASANT WEATHER SATURDAY NIGHT THROUGH THE
END OF THE WEEKEND.

MONDAY THROUGH WEDNESDAY...
THE UPPER FLOW WILL BE MORE DAMPENED AND THUS A LITTLE MORE
PROGRESSIVE. LONG RANGE ENSEMBLES AND FORECAST MODELS HAVE MODEST
AGREEMENT ON A JET MAXIMA TRAVERSING THE NORTHERN U.S. SOMETIME
MIDWEEK WITH AN ASSOCIATED WAVE IN THE MID-LEVELS AND A CLOSED
SURFACE LOW DEVELOPING IN THE PLAINS AND MOVING EASTWARD. GIVEN
THE DISTANCE THOUGH SEE LITTLE OPPORTUNITY TO IMPROVE MUCH FROM A
WELL-VERIFYING BLEND OF MODELS PROVIDING CHANCE POPS AREA-WIDE IN
THAT TIME PERIOD. WITH A CLOSED SURFACE LOW OF 1005 OR STRONGER ON
BOTH THE 31.00 GFS AND EC...CANT RULE OUT STRONGER STORMS IN THE
REGION BUT FAR TOO EARLY TO GET ANYWHERE NEAR SPECIFIC.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* ISOL -SHRA WITH A MINIMAL CHANCE OF TSRA.

JEE

//DISCUSSION...UPDATED 12Z...

A WEAK PRESSURE GRADIENT OVERHEAD IS LEADING TO LIGHT SOUTHWEST TO
WEST FLOW THIS MORNING. FOG WILL QUICKLY DISSIPATE AND WINDS WILL
PICK UP TO 10-15 KT. A LAKE BREEZE WILL FORM IN THE AFTERNOON BUT
THE FLOW SHOULD BE STRONG ENOUGH TO KEEP THE LAKE BREEZE JUST OFF
SHORE.

AN UPPER LEVEL WAVE APPROACHES FROM THE NW TODAY AND COMBINED WITH
THE LAKE BREEZE/S FORCING...SHOULD SEE ISOL SHRA DEVELOPMENT.
A FEW THUNDERSTORMS ARE POSSIBLE...BUT THEY SHOULD BE VERY
ISOLATED. WITH SUCH SPOTTY SHRA COVERAGE...DECIDED TO GO WITH DRY
TAFS EXCEPT FOR GYY. THE LAKE BREEZE WILL BE VERY CLOSE TO GYY SO
THINKING THE BEST BET FOR SHOWERS WILL BE AT GYY.

SHOWERS DISSIPATE IN THE EVENING AND LIGHT SW WINDS ARE EXPECTED.
COULD SEE ANOTHER ROUND OF PATCHY MVFR FOG...BUT HAVE LOW
CONFIDENCE SO LEFT IT OUT OF THE TAFS.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* MEDIUM CONFIDENCE IN SHRA COVERAGE AND LOCATION...LOW CONFIDENCE
  IN SHOWERS IMPACTING THE TERMINALS

* MEDIUM-HIGH CONFIDENCE IN A VERY VERY LOW CHANCE OF TSRA
  DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...

FRIDAY NIGHT...CHC SHRA.

SATURDAY...CHC SHRA THEN CHC OF AFTN TSRA.

SUNDAY...VFR.

MONDAY...SCHC TSRA DURING THE DAY AND CHC SHRA OVERNIGHT.

TUESDAY AND WEDNESDAY...CHC TSRA.

JEE

&&

.MARINE...
257 AM CDT

BROAD HIGH PRESSURE IS OVER THE REGION WITH A WEAK LOW OVER JAMES
BAY.  SOUTHWEST 10-15KT WINDS WILL BECOME SOUTH THIS AFTERNOON. MAY
SEE PATCHY FOG FORM OVER THE LAKE AGAIN...BUT WITH SHOWERS...A FEW
STORMS...AND DECENT FLOW...DECIDED TO KEEP PATCHY FOG OUT OF THE
GRIDS FOR NOW. IF FOG DOES FORM...IT WOULD BE IN THE AFTERNOON
THROUGH THE EVENING. A WEAK COLD FRONT WILL MOVE DOWN THE NORTH HALF
OF THE LAKE TONIGHT WITH WINDS BECOMING VARIABLE BEHIND IT. THE
SOUTH HALF WILL CONTINUE TO SEE SOUTHWEST WINDS. THE FRONT WILL
DISSIPATE OVER THE LAKE EARLY FRIDAY.

A CONTINUED LIGHT PRESSURE GRADIENT OVER THE LAKE THROUGH MONDAY
WILL MEAN SPEEDS LESS THAN 15 KT AND EVEN BEING VARIABLE AT
TIMES...WITH AFTERNOON LAKE BREEZES IN NEARSHORE AREAS. FRIDAY LOOKS
TO BE A DAY SIMILAR TO THIS PAST TUESDAY...WITH SCATTERED STORMS OF
OVER CENTRAL WI TO NORTHERN IL...SOME OF WHICH COULD BE GUSTY AND
TRAVERSE INTO THE WESTERN NEARSHORE AREAS WHERE STABILITY IS NOT
AS HIGH. SO WHILE GENERALLY TRANQUIL CONDITIONS THE NEXT SEVERAL
DAYS...THAT IS SOMETHING FOR MARINERS IN THE NEARSHORE TO BE AWARE
OF.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 311141
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
641 AM CDT THU JUL 31 2014

.DISCUSSION...
257 AM CDT

SYNOPSIS...ROUNDS OF AFTERNOON SHOWERS AND THUNDERSTORMS WILL
CONTINUE THROUGH THE END OF THE WEEK.  MINIMAL CHANCES OF THUNDER
TODAY...BUT HIGHER CHANCES LOOK TO ARRIVE TOMORROW AND SATURDAY.
TEMPERATURES REMAIN AROUND 80 THROUGH THE WEEKEND EXCEPT FOR ALONG
THE LAKE WHERE LAKE BREEZES WILL KEEP HIGHS IN THE 70S TOMORROW
THROUGH THE WEEKEND. A BRIEF WARM UP INTO THE MID 80S IS EXPECTED
EARLY NEXT WEEK.

TODAY AND TONIGHT...
PREPARE FOR A VERY FAMILIAR SONG AND DANCE...BROAD HIGH PRESSURE IS
OVER THE REGION WITH LIGHT FLOW AND PATCHY FOG. THE FOG WILL BURN
OFF QUICKLY THIS MORNING AS MIXING GETS GOING. LOOKING AT A BREEZY
DAY WITH WEST WINDS AT 10-15 KT. A LAKE BREEZE WILL FORM...BUT
EXPECTING IT TO STAY JUST OFF SHORE AS WIND SPEEDS ARE AT 10+ KT
THROUGH THE COLUMN.

AN UPPER LEVEL VORT STREAMER APPROACHES FROM THE NORTHWEST TODAY.
THEREFORE...WEAK FORCING WILL BE OVER NORTHERN IL AND FAR NORTHERN
IN...SO HAVE ANOTHER ROUND OF ISOLATED TO SCATTERED SHOWERS IN THE
FORECAST. BASED ON YESTERDAYS LIMITED ACTIVITY...THINKING WE WILL
SEE FEW IF ANY THUNDERSTORMS. THE DVN SOUNDING FEATURED A CAP
AROUND 650MB YESTERDAY AND MODEL GUIDANCE HAS A SIMILAR CAP IN
STORE FOR US TODAY. THE BEST CHANCE FOR SHOWERS WILL BE NORTH OF
I-80. NOT EXPECTING MUCH PRECIP FROM ANY SHOWERS THAT DO FORM.

HIGH TEMPS WILL BE AROUND 80 AND OVERNIGHT LOWS WILL BE AROUND
60...EXCEPT FOR THE MID 60S DOWNTOWN. MAY SEE FOG AGAIN TOMORROW
NIGHT...BUT NOT OVERLY IMPRESSED SO LEFT FOG OUT OF THE FORECAST FOR
NOW.

JEE

FRIDAY...
THE UPPER PATTERN REMAINS THE SAME FOR ONE MORE DAY INTO FRIDAY WITH
THE FORECAST AREA REMAINING ON THE SOUTHWEST SIDE OF THE EASTERN
CANADIAN LONG WAVE TROUGH. ONE OR TWO SHORT WAVE IMPULSES ARE
PROJECTED TO MOVE AROUND THE TROUGH IN THE NORTHWEST FLOW ALOFT
DURING THE DAY AND EVENING ON FRIDAY...KEEPING 500MB AND 700MB
TEMPERATURES AT ONE TO TWO STANDARDIZED ANOMALIES BELOW NORMAL.
COMBINED WITH A LITTLE MORE LOW-LEVEL HEATING ON FRIDAY...THE
SLIGHT WARM TEMPERATURE NOSE/CAP NEAR 650MB YESTERDAY AND TODAY IS
EXPECTED TO BE OVERCOME BY THIS AND THUS FORECAST SOUNDINGS
PROVIDE 800 TO 1300 J/KG OF MLCAPE OVER SOUTHERN WI/NORTHERN IL
DESPITE FORECAST DEW POINTS ONLY IN THE UPPER 50S. OVERALL
COVERAGE OF STORMS IS EXPECTED TO BE HIGHER IN THE REGION THAN THE
PAST COUPLE DAYS BECAUSE OF THIS...MAYBE SIMILAR TO TUESDAY. A
FEW STRONGER UPDRAFTS AND ASSOCIATED GUSTY DOWNDRAFTS ARE POSSIBLE
IN THE REGION DURING MID- AFTERNOON THROUGH MID-EVE.

THIS WEEKEND...
HIGH PRESSURE...ALBEIT WEAK...IS FORECAST TO BUILD SOUTHEASTWARD
ACROSS THE REGION EARLY IN THE WEEKEND IN ASSOCIATION WITH HEIGHT
RISES ALOFT. A DEVELOPING WEAK COOL FRONT AHEAD OF THE HIGH LOOKS
TO BE A MODEST FOCUS FOR SCATTERED AFTERNOON SHOWERS/STORMS IN THE
LOWER GREAT LAKES REGION. THIS COULD BE PRIMARILY EAST OF THE
LOCAL AREA BASED ON SOME GUIDANCE...BUT GIVEN THE MODEL SPREAD AND
THE SUBTLE FEATURES THAT COULD SPARK SOME SHOWERS...FELT PRUDENT
TO KEEP CHANCE POPS DURING THE DAY. NORTHEAST FLOW IS ANTICIPATED
TO DEVELOP AND DEPENDING ON TIMING COULD PROVIDE A STRONGER LAKE
BREEZE WITH AFTERNOON COOLING IN LAKE ADJACENT COUNTIES. THE HIGH
LOOKS TO MAKE FOR A PLEASANT WEATHER SATURDAY NIGHT THROUGH THE
END OF THE WEEKEND.

MONDAY THROUGH WEDNESDAY...
THE UPPER FLOW WILL BE MORE DAMPENED AND THUS A LITTLE MORE
PROGRESSIVE. LONG RANGE ENSEMBLES AND FORECAST MODELS HAVE MODEST
AGREEMENT ON A JET MAXIMA TRAVERSING THE NORTHERN U.S. SOMETIME
MIDWEEK WITH AN ASSOCIATED WAVE IN THE MID-LEVELS AND A CLOSED
SURFACE LOW DEVELOPING IN THE PLAINS AND MOVING EASTWARD. GIVEN
THE DISTANCE THOUGH SEE LITTLE OPPORTUNITY TO IMPROVE MUCH FROM A
WELL-VERIFYING BLEND OF MODELS PROVIDING CHANCE POPS AREA-WIDE IN
THAT TIME PERIOD. WITH A CLOSED SURFACE LOW OF 1005 OR STRONGER ON
BOTH THE 31.00 GFS AND EC...CANT RULE OUT STRONGER STORMS IN THE
REGION BUT FAR TOO EARLY TO GET ANYWHERE NEAR SPECIFIC.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* ISOL -SHRA WITH A MINIMAL CHANCE OF TSRA.

JEE

//DISCUSSION...UPDATED 12Z...

A WEAK PRESSURE GRADIENT OVERHEAD IS LEADING TO LIGHT SOUTHWEST TO
WEST FLOW THIS MORNING. FOG WILL QUICKLY DISSIPATE AND WINDS WILL
PICK UP TO 10-15 KT. A LAKE BREEZE WILL FORM IN THE AFTERNOON BUT
THE FLOW SHOULD BE STRONG ENOUGH TO KEEP THE LAKE BREEZE JUST OFF
SHORE.

AN UPPER LEVEL WAVE APPROACHES FROM THE NW TODAY AND COMBINED WITH
THE LAKE BREEZE/S FORCING...SHOULD SEE ISOL SHRA DEVELOPMENT.
A FEW THUNDERSTORMS ARE POSSIBLE...BUT THEY SHOULD BE VERY
ISOLATED. WITH SUCH SPOTTY SHRA COVERAGE...DECIDED TO GO WITH DRY
TAFS EXCEPT FOR GYY. THE LAKE BREEZE WILL BE VERY CLOSE TO GYY SO
THINKING THE BEST BET FOR SHOWERS WILL BE AT GYY.

SHOWERS DISSIPATE IN THE EVENING AND LIGHT SW WINDS ARE EXPECTED.
COULD SEE ANOTHER ROUND OF PATCHY MVFR FOG...BUT HAVE LOW
CONFIDENCE SO LEFT IT OUT OF THE TAFS.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* MEDIUM CONFIDENCE IN SHRA COVERAGE AND LOCATION...LOW CONFIDENCE
  IN SHOWERS IMPACTING THE TERMINALS

* MEDIUM-HIGH CONFIDENCE IN A VERY VERY LOW CHANCE OF TSRA
  DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...

FRIDAY NIGHT...CHC SHRA.

SATURDAY...CHC SHRA THEN CHC OF AFTN TSRA.

SUNDAY...VFR.

MONDAY...SCHC TSRA DURING THE DAY AND CHC SHRA OVERNIGHT.

TUESDAY AND WEDNESDAY...CHC TSRA.

JEE

&&

.MARINE...
257 AM CDT

BROAD HIGH PRESSURE IS OVER THE REGION WITH A WEAK LOW OVER JAMES
BAY.  SOUTHWEST 10-15KT WINDS WILL BECOME SOUTH THIS AFTERNOON. MAY
SEE PATCHY FOG FORM OVER THE LAKE AGAIN...BUT WITH SHOWERS...A FEW
STORMS...AND DECENT FLOW...DECIDED TO KEEP PATCHY FOG OUT OF THE
GRIDS FOR NOW. IF FOG DOES FORM...IT WOULD BE IN THE AFTERNOON
THROUGH THE EVENING. A WEAK COLD FRONT WILL MOVE DOWN THE NORTH HALF
OF THE LAKE TONIGHT WITH WINDS BECOMING VARIABLE BEHIND IT. THE
SOUTH HALF WILL CONTINUE TO SEE SOUTHWEST WINDS. THE FRONT WILL
DISSIPATE OVER THE LAKE EARLY FRIDAY.

A CONTINUED LIGHT PRESSURE GRADIENT OVER THE LAKE THROUGH MONDAY
WILL MEAN SPEEDS LESS THAN 15 KT AND EVEN BEING VARIABLE AT
TIMES...WITH AFTERNOON LAKE BREEZES IN NEARSHORE AREAS. FRIDAY LOOKS
TO BE A DAY SIMILAR TO THIS PAST TUESDAY...WITH SCATTERED STORMS OF
OVER CENTRAL WI TO NORTHERN IL...SOME OF WHICH COULD BE GUSTY AND
TRAVERSE INTO THE WESTERN NEARSHORE AREAS WHERE STABILITY IS NOT
AS HIGH. SO WHILE GENERALLY TRANQUIL CONDITIONS THE NEXT SEVERAL
DAYS...THAT IS SOMETHING FOR MARINERS IN THE NEARSHORE TO BE AWARE
OF.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 311141
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
641 AM CDT THU JUL 31 2014

.DISCUSSION...
257 AM CDT

SYNOPSIS...ROUNDS OF AFTERNOON SHOWERS AND THUNDERSTORMS WILL
CONTINUE THROUGH THE END OF THE WEEK.  MINIMAL CHANCES OF THUNDER
TODAY...BUT HIGHER CHANCES LOOK TO ARRIVE TOMORROW AND SATURDAY.
TEMPERATURES REMAIN AROUND 80 THROUGH THE WEEKEND EXCEPT FOR ALONG
THE LAKE WHERE LAKE BREEZES WILL KEEP HIGHS IN THE 70S TOMORROW
THROUGH THE WEEKEND. A BRIEF WARM UP INTO THE MID 80S IS EXPECTED
EARLY NEXT WEEK.

TODAY AND TONIGHT...
PREPARE FOR A VERY FAMILIAR SONG AND DANCE...BROAD HIGH PRESSURE IS
OVER THE REGION WITH LIGHT FLOW AND PATCHY FOG. THE FOG WILL BURN
OFF QUICKLY THIS MORNING AS MIXING GETS GOING. LOOKING AT A BREEZY
DAY WITH WEST WINDS AT 10-15 KT. A LAKE BREEZE WILL FORM...BUT
EXPECTING IT TO STAY JUST OFF SHORE AS WIND SPEEDS ARE AT 10+ KT
THROUGH THE COLUMN.

AN UPPER LEVEL VORT STREAMER APPROACHES FROM THE NORTHWEST TODAY.
THEREFORE...WEAK FORCING WILL BE OVER NORTHERN IL AND FAR NORTHERN
IN...SO HAVE ANOTHER ROUND OF ISOLATED TO SCATTERED SHOWERS IN THE
FORECAST. BASED ON YESTERDAYS LIMITED ACTIVITY...THINKING WE WILL
SEE FEW IF ANY THUNDERSTORMS. THE DVN SOUNDING FEATURED A CAP
AROUND 650MB YESTERDAY AND MODEL GUIDANCE HAS A SIMILAR CAP IN
STORE FOR US TODAY. THE BEST CHANCE FOR SHOWERS WILL BE NORTH OF
I-80. NOT EXPECTING MUCH PRECIP FROM ANY SHOWERS THAT DO FORM.

HIGH TEMPS WILL BE AROUND 80 AND OVERNIGHT LOWS WILL BE AROUND
60...EXCEPT FOR THE MID 60S DOWNTOWN. MAY SEE FOG AGAIN TOMORROW
NIGHT...BUT NOT OVERLY IMPRESSED SO LEFT FOG OUT OF THE FORECAST FOR
NOW.

JEE

FRIDAY...
THE UPPER PATTERN REMAINS THE SAME FOR ONE MORE DAY INTO FRIDAY WITH
THE FORECAST AREA REMAINING ON THE SOUTHWEST SIDE OF THE EASTERN
CANADIAN LONG WAVE TROUGH. ONE OR TWO SHORT WAVE IMPULSES ARE
PROJECTED TO MOVE AROUND THE TROUGH IN THE NORTHWEST FLOW ALOFT
DURING THE DAY AND EVENING ON FRIDAY...KEEPING 500MB AND 700MB
TEMPERATURES AT ONE TO TWO STANDARDIZED ANOMALIES BELOW NORMAL.
COMBINED WITH A LITTLE MORE LOW-LEVEL HEATING ON FRIDAY...THE
SLIGHT WARM TEMPERATURE NOSE/CAP NEAR 650MB YESTERDAY AND TODAY IS
EXPECTED TO BE OVERCOME BY THIS AND THUS FORECAST SOUNDINGS
PROVIDE 800 TO 1300 J/KG OF MLCAPE OVER SOUTHERN WI/NORTHERN IL
DESPITE FORECAST DEW POINTS ONLY IN THE UPPER 50S. OVERALL
COVERAGE OF STORMS IS EXPECTED TO BE HIGHER IN THE REGION THAN THE
PAST COUPLE DAYS BECAUSE OF THIS...MAYBE SIMILAR TO TUESDAY. A
FEW STRONGER UPDRAFTS AND ASSOCIATED GUSTY DOWNDRAFTS ARE POSSIBLE
IN THE REGION DURING MID- AFTERNOON THROUGH MID-EVE.

THIS WEEKEND...
HIGH PRESSURE...ALBEIT WEAK...IS FORECAST TO BUILD SOUTHEASTWARD
ACROSS THE REGION EARLY IN THE WEEKEND IN ASSOCIATION WITH HEIGHT
RISES ALOFT. A DEVELOPING WEAK COOL FRONT AHEAD OF THE HIGH LOOKS
TO BE A MODEST FOCUS FOR SCATTERED AFTERNOON SHOWERS/STORMS IN THE
LOWER GREAT LAKES REGION. THIS COULD BE PRIMARILY EAST OF THE
LOCAL AREA BASED ON SOME GUIDANCE...BUT GIVEN THE MODEL SPREAD AND
THE SUBTLE FEATURES THAT COULD SPARK SOME SHOWERS...FELT PRUDENT
TO KEEP CHANCE POPS DURING THE DAY. NORTHEAST FLOW IS ANTICIPATED
TO DEVELOP AND DEPENDING ON TIMING COULD PROVIDE A STRONGER LAKE
BREEZE WITH AFTERNOON COOLING IN LAKE ADJACENT COUNTIES. THE HIGH
LOOKS TO MAKE FOR A PLEASANT WEATHER SATURDAY NIGHT THROUGH THE
END OF THE WEEKEND.

MONDAY THROUGH WEDNESDAY...
THE UPPER FLOW WILL BE MORE DAMPENED AND THUS A LITTLE MORE
PROGRESSIVE. LONG RANGE ENSEMBLES AND FORECAST MODELS HAVE MODEST
AGREEMENT ON A JET MAXIMA TRAVERSING THE NORTHERN U.S. SOMETIME
MIDWEEK WITH AN ASSOCIATED WAVE IN THE MID-LEVELS AND A CLOSED
SURFACE LOW DEVELOPING IN THE PLAINS AND MOVING EASTWARD. GIVEN
THE DISTANCE THOUGH SEE LITTLE OPPORTUNITY TO IMPROVE MUCH FROM A
WELL-VERIFYING BLEND OF MODELS PROVIDING CHANCE POPS AREA-WIDE IN
THAT TIME PERIOD. WITH A CLOSED SURFACE LOW OF 1005 OR STRONGER ON
BOTH THE 31.00 GFS AND EC...CANT RULE OUT STRONGER STORMS IN THE
REGION BUT FAR TOO EARLY TO GET ANYWHERE NEAR SPECIFIC.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* ISOL -SHRA WITH A MINIMAL CHANCE OF TSRA.

JEE

//DISCUSSION...UPDATED 12Z...

A WEAK PRESSURE GRADIENT OVERHEAD IS LEADING TO LIGHT SOUTHWEST TO
WEST FLOW THIS MORNING. FOG WILL QUICKLY DISSIPATE AND WINDS WILL
PICK UP TO 10-15 KT. A LAKE BREEZE WILL FORM IN THE AFTERNOON BUT
THE FLOW SHOULD BE STRONG ENOUGH TO KEEP THE LAKE BREEZE JUST OFF
SHORE.

AN UPPER LEVEL WAVE APPROACHES FROM THE NW TODAY AND COMBINED WITH
THE LAKE BREEZE/S FORCING...SHOULD SEE ISOL SHRA DEVELOPMENT.
A FEW THUNDERSTORMS ARE POSSIBLE...BUT THEY SHOULD BE VERY
ISOLATED. WITH SUCH SPOTTY SHRA COVERAGE...DECIDED TO GO WITH DRY
TAFS EXCEPT FOR GYY. THE LAKE BREEZE WILL BE VERY CLOSE TO GYY SO
THINKING THE BEST BET FOR SHOWERS WILL BE AT GYY.

SHOWERS DISSIPATE IN THE EVENING AND LIGHT SW WINDS ARE EXPECTED.
COULD SEE ANOTHER ROUND OF PATCHY MVFR FOG...BUT HAVE LOW
CONFIDENCE SO LEFT IT OUT OF THE TAFS.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* MEDIUM CONFIDENCE IN SHRA COVERAGE AND LOCATION...LOW CONFIDENCE
  IN SHOWERS IMPACTING THE TERMINALS

* MEDIUM-HIGH CONFIDENCE IN A VERY VERY LOW CHANCE OF TSRA
  DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...

FRIDAY NIGHT...CHC SHRA.

SATURDAY...CHC SHRA THEN CHC OF AFTN TSRA.

SUNDAY...VFR.

MONDAY...SCHC TSRA DURING THE DAY AND CHC SHRA OVERNIGHT.

TUESDAY AND WEDNESDAY...CHC TSRA.

JEE

&&

.MARINE...
257 AM CDT

BROAD HIGH PRESSURE IS OVER THE REGION WITH A WEAK LOW OVER JAMES
BAY.  SOUTHWEST 10-15KT WINDS WILL BECOME SOUTH THIS AFTERNOON. MAY
SEE PATCHY FOG FORM OVER THE LAKE AGAIN...BUT WITH SHOWERS...A FEW
STORMS...AND DECENT FLOW...DECIDED TO KEEP PATCHY FOG OUT OF THE
GRIDS FOR NOW. IF FOG DOES FORM...IT WOULD BE IN THE AFTERNOON
THROUGH THE EVENING. A WEAK COLD FRONT WILL MOVE DOWN THE NORTH HALF
OF THE LAKE TONIGHT WITH WINDS BECOMING VARIABLE BEHIND IT. THE
SOUTH HALF WILL CONTINUE TO SEE SOUTHWEST WINDS. THE FRONT WILL
DISSIPATE OVER THE LAKE EARLY FRIDAY.

A CONTINUED LIGHT PRESSURE GRADIENT OVER THE LAKE THROUGH MONDAY
WILL MEAN SPEEDS LESS THAN 15 KT AND EVEN BEING VARIABLE AT
TIMES...WITH AFTERNOON LAKE BREEZES IN NEARSHORE AREAS. FRIDAY LOOKS
TO BE A DAY SIMILAR TO THIS PAST TUESDAY...WITH SCATTERED STORMS OF
OVER CENTRAL WI TO NORTHERN IL...SOME OF WHICH COULD BE GUSTY AND
TRAVERSE INTO THE WESTERN NEARSHORE AREAS WHERE STABILITY IS NOT
AS HIGH. SO WHILE GENERALLY TRANQUIL CONDITIONS THE NEXT SEVERAL
DAYS...THAT IS SOMETHING FOR MARINERS IN THE NEARSHORE TO BE AWARE
OF.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 311141
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
641 AM CDT THU JUL 31 2014

.DISCUSSION...
257 AM CDT

SYNOPSIS...ROUNDS OF AFTERNOON SHOWERS AND THUNDERSTORMS WILL
CONTINUE THROUGH THE END OF THE WEEK.  MINIMAL CHANCES OF THUNDER
TODAY...BUT HIGHER CHANCES LOOK TO ARRIVE TOMORROW AND SATURDAY.
TEMPERATURES REMAIN AROUND 80 THROUGH THE WEEKEND EXCEPT FOR ALONG
THE LAKE WHERE LAKE BREEZES WILL KEEP HIGHS IN THE 70S TOMORROW
THROUGH THE WEEKEND. A BRIEF WARM UP INTO THE MID 80S IS EXPECTED
EARLY NEXT WEEK.

TODAY AND TONIGHT...
PREPARE FOR A VERY FAMILIAR SONG AND DANCE...BROAD HIGH PRESSURE IS
OVER THE REGION WITH LIGHT FLOW AND PATCHY FOG. THE FOG WILL BURN
OFF QUICKLY THIS MORNING AS MIXING GETS GOING. LOOKING AT A BREEZY
DAY WITH WEST WINDS AT 10-15 KT. A LAKE BREEZE WILL FORM...BUT
EXPECTING IT TO STAY JUST OFF SHORE AS WIND SPEEDS ARE AT 10+ KT
THROUGH THE COLUMN.

AN UPPER LEVEL VORT STREAMER APPROACHES FROM THE NORTHWEST TODAY.
THEREFORE...WEAK FORCING WILL BE OVER NORTHERN IL AND FAR NORTHERN
IN...SO HAVE ANOTHER ROUND OF ISOLATED TO SCATTERED SHOWERS IN THE
FORECAST. BASED ON YESTERDAYS LIMITED ACTIVITY...THINKING WE WILL
SEE FEW IF ANY THUNDERSTORMS. THE DVN SOUNDING FEATURED A CAP
AROUND 650MB YESTERDAY AND MODEL GUIDANCE HAS A SIMILAR CAP IN
STORE FOR US TODAY. THE BEST CHANCE FOR SHOWERS WILL BE NORTH OF
I-80. NOT EXPECTING MUCH PRECIP FROM ANY SHOWERS THAT DO FORM.

HIGH TEMPS WILL BE AROUND 80 AND OVERNIGHT LOWS WILL BE AROUND
60...EXCEPT FOR THE MID 60S DOWNTOWN. MAY SEE FOG AGAIN TOMORROW
NIGHT...BUT NOT OVERLY IMPRESSED SO LEFT FOG OUT OF THE FORECAST FOR
NOW.

JEE

FRIDAY...
THE UPPER PATTERN REMAINS THE SAME FOR ONE MORE DAY INTO FRIDAY WITH
THE FORECAST AREA REMAINING ON THE SOUTHWEST SIDE OF THE EASTERN
CANADIAN LONG WAVE TROUGH. ONE OR TWO SHORT WAVE IMPULSES ARE
PROJECTED TO MOVE AROUND THE TROUGH IN THE NORTHWEST FLOW ALOFT
DURING THE DAY AND EVENING ON FRIDAY...KEEPING 500MB AND 700MB
TEMPERATURES AT ONE TO TWO STANDARDIZED ANOMALIES BELOW NORMAL.
COMBINED WITH A LITTLE MORE LOW-LEVEL HEATING ON FRIDAY...THE
SLIGHT WARM TEMPERATURE NOSE/CAP NEAR 650MB YESTERDAY AND TODAY IS
EXPECTED TO BE OVERCOME BY THIS AND THUS FORECAST SOUNDINGS
PROVIDE 800 TO 1300 J/KG OF MLCAPE OVER SOUTHERN WI/NORTHERN IL
DESPITE FORECAST DEW POINTS ONLY IN THE UPPER 50S. OVERALL
COVERAGE OF STORMS IS EXPECTED TO BE HIGHER IN THE REGION THAN THE
PAST COUPLE DAYS BECAUSE OF THIS...MAYBE SIMILAR TO TUESDAY. A
FEW STRONGER UPDRAFTS AND ASSOCIATED GUSTY DOWNDRAFTS ARE POSSIBLE
IN THE REGION DURING MID- AFTERNOON THROUGH MID-EVE.

THIS WEEKEND...
HIGH PRESSURE...ALBEIT WEAK...IS FORECAST TO BUILD SOUTHEASTWARD
ACROSS THE REGION EARLY IN THE WEEKEND IN ASSOCIATION WITH HEIGHT
RISES ALOFT. A DEVELOPING WEAK COOL FRONT AHEAD OF THE HIGH LOOKS
TO BE A MODEST FOCUS FOR SCATTERED AFTERNOON SHOWERS/STORMS IN THE
LOWER GREAT LAKES REGION. THIS COULD BE PRIMARILY EAST OF THE
LOCAL AREA BASED ON SOME GUIDANCE...BUT GIVEN THE MODEL SPREAD AND
THE SUBTLE FEATURES THAT COULD SPARK SOME SHOWERS...FELT PRUDENT
TO KEEP CHANCE POPS DURING THE DAY. NORTHEAST FLOW IS ANTICIPATED
TO DEVELOP AND DEPENDING ON TIMING COULD PROVIDE A STRONGER LAKE
BREEZE WITH AFTERNOON COOLING IN LAKE ADJACENT COUNTIES. THE HIGH
LOOKS TO MAKE FOR A PLEASANT WEATHER SATURDAY NIGHT THROUGH THE
END OF THE WEEKEND.

MONDAY THROUGH WEDNESDAY...
THE UPPER FLOW WILL BE MORE DAMPENED AND THUS A LITTLE MORE
PROGRESSIVE. LONG RANGE ENSEMBLES AND FORECAST MODELS HAVE MODEST
AGREEMENT ON A JET MAXIMA TRAVERSING THE NORTHERN U.S. SOMETIME
MIDWEEK WITH AN ASSOCIATED WAVE IN THE MID-LEVELS AND A CLOSED
SURFACE LOW DEVELOPING IN THE PLAINS AND MOVING EASTWARD. GIVEN
THE DISTANCE THOUGH SEE LITTLE OPPORTUNITY TO IMPROVE MUCH FROM A
WELL-VERIFYING BLEND OF MODELS PROVIDING CHANCE POPS AREA-WIDE IN
THAT TIME PERIOD. WITH A CLOSED SURFACE LOW OF 1005 OR STRONGER ON
BOTH THE 31.00 GFS AND EC...CANT RULE OUT STRONGER STORMS IN THE
REGION BUT FAR TOO EARLY TO GET ANYWHERE NEAR SPECIFIC.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* ISOL -SHRA WITH A MINIMAL CHANCE OF TSRA.

JEE

//DISCUSSION...UPDATED 12Z...

A WEAK PRESSURE GRADIENT OVERHEAD IS LEADING TO LIGHT SOUTHWEST TO
WEST FLOW THIS MORNING. FOG WILL QUICKLY DISSIPATE AND WINDS WILL
PICK UP TO 10-15 KT. A LAKE BREEZE WILL FORM IN THE AFTERNOON BUT
THE FLOW SHOULD BE STRONG ENOUGH TO KEEP THE LAKE BREEZE JUST OFF
SHORE.

AN UPPER LEVEL WAVE APPROACHES FROM THE NW TODAY AND COMBINED WITH
THE LAKE BREEZE/S FORCING...SHOULD SEE ISOL SHRA DEVELOPMENT.
A FEW THUNDERSTORMS ARE POSSIBLE...BUT THEY SHOULD BE VERY
ISOLATED. WITH SUCH SPOTTY SHRA COVERAGE...DECIDED TO GO WITH DRY
TAFS EXCEPT FOR GYY. THE LAKE BREEZE WILL BE VERY CLOSE TO GYY SO
THINKING THE BEST BET FOR SHOWERS WILL BE AT GYY.

SHOWERS DISSIPATE IN THE EVENING AND LIGHT SW WINDS ARE EXPECTED.
COULD SEE ANOTHER ROUND OF PATCHY MVFR FOG...BUT HAVE LOW
CONFIDENCE SO LEFT IT OUT OF THE TAFS.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* MEDIUM CONFIDENCE IN SHRA COVERAGE AND LOCATION...LOW CONFIDENCE
  IN SHOWERS IMPACTING THE TERMINALS

* MEDIUM-HIGH CONFIDENCE IN A VERY VERY LOW CHANCE OF TSRA
  DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z...

FRIDAY NIGHT...CHC SHRA.

SATURDAY...CHC SHRA THEN CHC OF AFTN TSRA.

SUNDAY...VFR.

MONDAY...SCHC TSRA DURING THE DAY AND CHC SHRA OVERNIGHT.

TUESDAY AND WEDNESDAY...CHC TSRA.

JEE

&&

.MARINE...
257 AM CDT

BROAD HIGH PRESSURE IS OVER THE REGION WITH A WEAK LOW OVER JAMES
BAY.  SOUTHWEST 10-15KT WINDS WILL BECOME SOUTH THIS AFTERNOON. MAY
SEE PATCHY FOG FORM OVER THE LAKE AGAIN...BUT WITH SHOWERS...A FEW
STORMS...AND DECENT FLOW...DECIDED TO KEEP PATCHY FOG OUT OF THE
GRIDS FOR NOW. IF FOG DOES FORM...IT WOULD BE IN THE AFTERNOON
THROUGH THE EVENING. A WEAK COLD FRONT WILL MOVE DOWN THE NORTH HALF
OF THE LAKE TONIGHT WITH WINDS BECOMING VARIABLE BEHIND IT. THE
SOUTH HALF WILL CONTINUE TO SEE SOUTHWEST WINDS. THE FRONT WILL
DISSIPATE OVER THE LAKE EARLY FRIDAY.

A CONTINUED LIGHT PRESSURE GRADIENT OVER THE LAKE THROUGH MONDAY
WILL MEAN SPEEDS LESS THAN 15 KT AND EVEN BEING VARIABLE AT
TIMES...WITH AFTERNOON LAKE BREEZES IN NEARSHORE AREAS. FRIDAY LOOKS
TO BE A DAY SIMILAR TO THIS PAST TUESDAY...WITH SCATTERED STORMS OF
OVER CENTRAL WI TO NORTHERN IL...SOME OF WHICH COULD BE GUSTY AND
TRAVERSE INTO THE WESTERN NEARSHORE AREAS WHERE STABILITY IS NOT
AS HIGH. SO WHILE GENERALLY TRANQUIL CONDITIONS THE NEXT SEVERAL
DAYS...THAT IS SOMETHING FOR MARINERS IN THE NEARSHORE TO BE AWARE
OF.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





  [top]

000
FXUS63 KILX 311115
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
615 AM CDT Thu Jul 31 2014

.DISCUSSION...
ISSUED 311 AM CDT Thu Jul 31 2014
Very little changing in this forecast. Deep low over southeastern
Canada keeping the eastern half of the country dominated by the
500mb trof. Northwesterly flow over the Plains and into the
Midwest. Ridging over the west building up some warm air that will
start to edge towards the region by the end of the forecast
period. Diurnal element to cloud cover and some shower activity
possible to the northeast today...and a series of waves diving
into and around the upper trof will bring better chances for
scattered showers/thunderstorms for Friday and Saturday. Watching
forecast soundings for tomorrows potential thunderstorms and
severe weather chances. Forecast drying out for the latter half of
the weekend and into Monday until another wave moves on the
western coast, kicking the eastern trof out of the stagnant
pattern. A more progressive series of waves begins to drive better
rain chances for the remainder of the forecast.

SHORT TERM...Today and tomorrow...
Mild again today with light winds, just below normal max temps.
Sunshine and afternoon clouds with some of the heavier clouds to
the northeast possibly providing a sparse shower. Tomorrow,
chances improve with a wave diving into the trof and enhancing the
afternoon instability. Wind profiles very weak, but lower freezing
level and pretty good lapse rates tomorrow afternoon could result
in some good updrafts should thunderstorms develop. SPC has put
the area in a see text for marginal hail threat with the daytime
heating/shortwave thunderstorms  in the afternoon.

LONG TERM...Saturday through Tuesday...
Models beginning to send another wave into the trof for Saturday,
with almost a repeat of Friday with similar forecast soundings.
Beginning to trend the forecast to scattered showers and
thunderstorms for Saturday as well should the signal continue.
Though the thunderstorm development will be countered by
increasing subsidence with ridge moving closer to the area. High
pressure dominating remains of weekend as the sfc ridge axis moves
into the region. Winds remain light and variable and dry forecast
as the upper trof finally starts to progress across into the NE.
Chances for more significant weather starting to return Tues/Wed
as a more active and progressive flow sets up across the country.

HJS

&&

.AVIATION...
ISSUED 615 AM CDT Thu Jul 31 2014

Mainly VFR conditions expected for the next 24 hours. Fairly
light west-northwest flow over central Illinois with a large scale
trough over the eastern U.S. will continue. Slightly lighter
winds this morning have allowed patchy, thin, and shallow fog to
form and this will dissipate over the next few hours as daytime
heating begins. Local IFR/MVFR conditions should be expected until
13-14Z. By afternoon, daytime heating will allow for scattered cloud
cover at around 5 kft MSL with isolated shra/tsra...mainly KPRG-
KC75 northward. Isolated MVFR conditions can`t be ruled out, but
will be too low probability for mention in area TAFs. After
00Z...any shower activity/cloud cover diminishing. Winds
increasing to W5-8 kts by 15Z...becoming light and variable by
00Z.

Onton

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KILX 311115
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
615 AM CDT Thu Jul 31 2014

.DISCUSSION...
ISSUED 311 AM CDT Thu Jul 31 2014
Very little changing in this forecast. Deep low over southeastern
Canada keeping the eastern half of the country dominated by the
500mb trof. Northwesterly flow over the Plains and into the
Midwest. Ridging over the west building up some warm air that will
start to edge towards the region by the end of the forecast
period. Diurnal element to cloud cover and some shower activity
possible to the northeast today...and a series of waves diving
into and around the upper trof will bring better chances for
scattered showers/thunderstorms for Friday and Saturday. Watching
forecast soundings for tomorrows potential thunderstorms and
severe weather chances. Forecast drying out for the latter half of
the weekend and into Monday until another wave moves on the
western coast, kicking the eastern trof out of the stagnant
pattern. A more progressive series of waves begins to drive better
rain chances for the remainder of the forecast.

SHORT TERM...Today and tomorrow...
Mild again today with light winds, just below normal max temps.
Sunshine and afternoon clouds with some of the heavier clouds to
the northeast possibly providing a sparse shower. Tomorrow,
chances improve with a wave diving into the trof and enhancing the
afternoon instability. Wind profiles very weak, but lower freezing
level and pretty good lapse rates tomorrow afternoon could result
in some good updrafts should thunderstorms develop. SPC has put
the area in a see text for marginal hail threat with the daytime
heating/shortwave thunderstorms  in the afternoon.

LONG TERM...Saturday through Tuesday...
Models beginning to send another wave into the trof for Saturday,
with almost a repeat of Friday with similar forecast soundings.
Beginning to trend the forecast to scattered showers and
thunderstorms for Saturday as well should the signal continue.
Though the thunderstorm development will be countered by
increasing subsidence with ridge moving closer to the area. High
pressure dominating remains of weekend as the sfc ridge axis moves
into the region. Winds remain light and variable and dry forecast
as the upper trof finally starts to progress across into the NE.
Chances for more significant weather starting to return Tues/Wed
as a more active and progressive flow sets up across the country.

HJS

&&

.AVIATION...
ISSUED 615 AM CDT Thu Jul 31 2014

Mainly VFR conditions expected for the next 24 hours. Fairly
light west-northwest flow over central Illinois with a large scale
trough over the eastern U.S. will continue. Slightly lighter
winds this morning have allowed patchy, thin, and shallow fog to
form and this will dissipate over the next few hours as daytime
heating begins. Local IFR/MVFR conditions should be expected until
13-14Z. By afternoon, daytime heating will allow for scattered cloud
cover at around 5 kft MSL with isolated shra/tsra...mainly KPRG-
KC75 northward. Isolated MVFR conditions can`t be ruled out, but
will be too low probability for mention in area TAFs. After
00Z...any shower activity/cloud cover diminishing. Winds
increasing to W5-8 kts by 15Z...becoming light and variable by
00Z.

Onton

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KILX 311115
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
615 AM CDT Thu Jul 31 2014

.DISCUSSION...
ISSUED 311 AM CDT Thu Jul 31 2014
Very little changing in this forecast. Deep low over southeastern
Canada keeping the eastern half of the country dominated by the
500mb trof. Northwesterly flow over the Plains and into the
Midwest. Ridging over the west building up some warm air that will
start to edge towards the region by the end of the forecast
period. Diurnal element to cloud cover and some shower activity
possible to the northeast today...and a series of waves diving
into and around the upper trof will bring better chances for
scattered showers/thunderstorms for Friday and Saturday. Watching
forecast soundings for tomorrows potential thunderstorms and
severe weather chances. Forecast drying out for the latter half of
the weekend and into Monday until another wave moves on the
western coast, kicking the eastern trof out of the stagnant
pattern. A more progressive series of waves begins to drive better
rain chances for the remainder of the forecast.

SHORT TERM...Today and tomorrow...
Mild again today with light winds, just below normal max temps.
Sunshine and afternoon clouds with some of the heavier clouds to
the northeast possibly providing a sparse shower. Tomorrow,
chances improve with a wave diving into the trof and enhancing the
afternoon instability. Wind profiles very weak, but lower freezing
level and pretty good lapse rates tomorrow afternoon could result
in some good updrafts should thunderstorms develop. SPC has put
the area in a see text for marginal hail threat with the daytime
heating/shortwave thunderstorms  in the afternoon.

LONG TERM...Saturday through Tuesday...
Models beginning to send another wave into the trof for Saturday,
with almost a repeat of Friday with similar forecast soundings.
Beginning to trend the forecast to scattered showers and
thunderstorms for Saturday as well should the signal continue.
Though the thunderstorm development will be countered by
increasing subsidence with ridge moving closer to the area. High
pressure dominating remains of weekend as the sfc ridge axis moves
into the region. Winds remain light and variable and dry forecast
as the upper trof finally starts to progress across into the NE.
Chances for more significant weather starting to return Tues/Wed
as a more active and progressive flow sets up across the country.

HJS

&&

.AVIATION...
ISSUED 615 AM CDT Thu Jul 31 2014

Mainly VFR conditions expected for the next 24 hours. Fairly
light west-northwest flow over central Illinois with a large scale
trough over the eastern U.S. will continue. Slightly lighter
winds this morning have allowed patchy, thin, and shallow fog to
form and this will dissipate over the next few hours as daytime
heating begins. Local IFR/MVFR conditions should be expected until
13-14Z. By afternoon, daytime heating will allow for scattered cloud
cover at around 5 kft MSL with isolated shra/tsra...mainly KPRG-
KC75 northward. Isolated MVFR conditions can`t be ruled out, but
will be too low probability for mention in area TAFs. After
00Z...any shower activity/cloud cover diminishing. Winds
increasing to W5-8 kts by 15Z...becoming light and variable by
00Z.

Onton

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KILX 311115
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
615 AM CDT Thu Jul 31 2014

.DISCUSSION...
ISSUED 311 AM CDT Thu Jul 31 2014
Very little changing in this forecast. Deep low over southeastern
Canada keeping the eastern half of the country dominated by the
500mb trof. Northwesterly flow over the Plains and into the
Midwest. Ridging over the west building up some warm air that will
start to edge towards the region by the end of the forecast
period. Diurnal element to cloud cover and some shower activity
possible to the northeast today...and a series of waves diving
into and around the upper trof will bring better chances for
scattered showers/thunderstorms for Friday and Saturday. Watching
forecast soundings for tomorrows potential thunderstorms and
severe weather chances. Forecast drying out for the latter half of
the weekend and into Monday until another wave moves on the
western coast, kicking the eastern trof out of the stagnant
pattern. A more progressive series of waves begins to drive better
rain chances for the remainder of the forecast.

SHORT TERM...Today and tomorrow...
Mild again today with light winds, just below normal max temps.
Sunshine and afternoon clouds with some of the heavier clouds to
the northeast possibly providing a sparse shower. Tomorrow,
chances improve with a wave diving into the trof and enhancing the
afternoon instability. Wind profiles very weak, but lower freezing
level and pretty good lapse rates tomorrow afternoon could result
in some good updrafts should thunderstorms develop. SPC has put
the area in a see text for marginal hail threat with the daytime
heating/shortwave thunderstorms  in the afternoon.

LONG TERM...Saturday through Tuesday...
Models beginning to send another wave into the trof for Saturday,
with almost a repeat of Friday with similar forecast soundings.
Beginning to trend the forecast to scattered showers and
thunderstorms for Saturday as well should the signal continue.
Though the thunderstorm development will be countered by
increasing subsidence with ridge moving closer to the area. High
pressure dominating remains of weekend as the sfc ridge axis moves
into the region. Winds remain light and variable and dry forecast
as the upper trof finally starts to progress across into the NE.
Chances for more significant weather starting to return Tues/Wed
as a more active and progressive flow sets up across the country.

HJS

&&

.AVIATION...
ISSUED 615 AM CDT Thu Jul 31 2014

Mainly VFR conditions expected for the next 24 hours. Fairly
light west-northwest flow over central Illinois with a large scale
trough over the eastern U.S. will continue. Slightly lighter
winds this morning have allowed patchy, thin, and shallow fog to
form and this will dissipate over the next few hours as daytime
heating begins. Local IFR/MVFR conditions should be expected until
13-14Z. By afternoon, daytime heating will allow for scattered cloud
cover at around 5 kft MSL with isolated shra/tsra...mainly KPRG-
KC75 northward. Isolated MVFR conditions can`t be ruled out, but
will be too low probability for mention in area TAFs. After
00Z...any shower activity/cloud cover diminishing. Winds
increasing to W5-8 kts by 15Z...becoming light and variable by
00Z.

Onton

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 310858
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
358 AM CDT THU JUL 31 2014

.DISCUSSION...
257 AM CDT

SYNOPSIS...ROUNDS OF AFTERNOON SHOWERS AND THUNDERSTORMS WILL
CONTINUE THROUGH THE END OF THE WEEK.  MINIMAL CHANCES OF THUNDER
TODAY...BUT HIGHER CHANCES LOOK TO ARRIVE TOMORROW AND SATURDAY.
TEMPERATURES REMAIN AROUND 80 THROUGH THE WEEKEND EXCEPT FOR ALONG
THE LAKE WHERE LAKE BREEZES WILL KEEP HIGHS IN THE 70S TOMORROW
THROUGH THE WEEKEND. A BRIEF WARM UP INTO THE MID 80S IS EXPECTED
EARLY NEXT WEEK.

TODAY AND TONIGHT...
PREPARE FOR A VERY FAMILIAR SONG AND DANCE...BROAD HIGH PRESSURE IS
OVER THE REGION WITH LIGHT FLOW AND PATCHY FOG. THE FOG WILL BURN
OFF QUICKLY THIS MORNING AS MIXING GETS GOING. LOOKING AT A BREEZY
DAY WITH WEST WINDS AT 10-15 KT. A LAKE BREEZE WILL FORM...BUT
EXPECTING IT TO STAY JUST OFF SHORE AS WIND SPEEDS ARE AT 10+ KT
THROUGH THE COLUMN.

AN UPPER LEVEL VORT STREAMER APPROACHES FROM THE NORTHWEST TODAY.
THEREFORE...WEAK FORCING WILL BE OVER NORTHERN IL AND FAR NORTHERN
IN...SO HAVE ANOTHER ROUND OF ISOLATED TO SCATTERED SHOWERS IN THE
FORECAST. BASED ON YESTERDAYS LIMITED ACTIVITY...THINKING WE WILL
SEE FEW IF ANY THUNDERSTORMS. THE DVN SOUNDING FEATURED A CAP
AROUND 650MB YESTERDAY AND MODEL GUIDANCE HAS A SIMILAR CAP IN
STORE FOR US TODAY. THE BEST CHANCE FOR SHOWERS WILL BE NORTH OF
I-80. NOT EXPECTING MUCH PRECIP FROM ANY SHOWERS THAT DO FORM.

HIGH TEMPS WILL BE AROUND 80 AND OVERNIGHT LOWS WILL BE AROUND
60...EXCEPT FOR THE MID 60S DOWNTOWN. MAY SEE FOG AGAIN TOMORROW
NIGHT...BUT NOT OVERLY IMPRESSED SO LEFT FOG OUT OF THE FORECAST FOR
NOW.

JEE

FRIDAY...
THE UPPER PATTERN REMAINS THE SAME FOR ONE MORE DAY INTO FRIDAY WITH
THE FORECAST AREA REMAINING ON THE SOUTHWEST SIDE OF THE EASTERN
CANADIAN LONG WAVE TROUGH. ONE OR TWO SHORT WAVE IMPULSES ARE
PROJECTED TO MOVE AROUND THE TROUGH IN THE NORTHWEST FLOW ALOFT
DURING THE DAY AND EVENING ON FRIDAY...KEEPING 500MB AND 700MB
TEMPERATURES AT ONE TO TWO STANDARDIZED ANOMALIES BELOW NORMAL.
COMBINED WITH A LITTLE MORE LOW-LEVEL HEATING ON FRIDAY...THE
SLIGHT WARM TEMPERATURE NOSE/CAP NEAR 650MB YESTERDAY AND TODAY IS
EXPECTED TO BE OVERCOME BY THIS AND THUS FORECAST SOUNDINGS
PROVIDE 800 TO 1300 J/KG OF MLCAPE OVER SOUTHERN WI/NORTHERN IL
DESPITE FORECAST DEW POINTS ONLY IN THE UPPER 50S. OVERALL
COVERAGE OF STORMS IS EXPECTED TO BE HIGHER IN THE REGION THAN THE
PAST COUPLE DAYS BECAUSE OF THIS...MAYBE SIMILAR TO TUESDAY. A
FEW STRONGER UPDRAFTS AND ASSOCIATED GUSTY DOWNDRAFTS ARE POSSIBLE
IN THE REGION DURING MID- AFTERNOON THROUGH MID-EVE.

THIS WEEKEND...
HIGH PRESSURE...ALBEIT WEAK...IS FORECAST TO BUILD SOUTHEASTWARD
ACROSS THE REGION EARLY IN THE WEEKEND IN ASSOCIATION WITH HEIGHT
RISES ALOFT. A DEVELOPING WEAK COOL FRONT AHEAD OF THE HIGH LOOKS
TO BE A MODEST FOCUS FOR SCATTERED AFTERNOON SHOWERS/STORMS IN THE
LOWER GREAT LAKES REGION. THIS COULD BE PRIMARILY EAST OF THE
LOCAL AREA BASED ON SOME GUIDANCE...BUT GIVEN THE MODEL SPREAD AND
THE SUBTLE FEATURES THAT COULD SPARK SOME SHOWERS...FELT PRUDENT
TO KEEP CHANCE POPS DURING THE DAY. NORTHEAST FLOW IS ANTICIPATED
TO DEVELOP AND DEPENDING ON TIMING COULD PROVIDE A STRONGER LAKE
BREEZE WITH AFTERNOON COOLING IN LAKE ADJACENT COUNTIES. THE HIGH
LOOKS TO MAKE FOR A PLEASANT WEATHER SATURDAY NIGHT THROUGH THE
END OF THE WEEKEND.

MONDAY THROUGH WEDNESDAY...
THE UPPER FLOW WILL BE MORE DAMPENED AND THUS A LITTLE MORE
PROGRESSIVE. LONG RANGE ENSEMBLES AND FORECAST MODELS HAVE MODEST
AGREEMENT ON A JET MAXIMA TRAVERSING THE NORTHERN U.S. SOMETIME
MIDWEEK WITH AN ASSOCIATED WAVE IN THE MID-LEVELS AND A CLOSED
SURFACE LOW DEVELOPING IN THE PLAINS AND MOVING EASTWARD. GIVEN
THE DISTANCE THOUGH SEE LITTLE OPPORTUNITY TO IMPROVE MUCH FROM A
WELL-VERIFYING BLEND OF MODELS PROVIDING CHANCE POPS AREA-WIDE IN
THAT TIME PERIOD. WITH A CLOSED SURFACE LOW OF 1005 OR STRONGER ON
BOTH THE 31.00 GFS AND EC...CANT RULE OUT STRONGER STORMS IN THE
REGION BUT FAR TOO EARLY TO GET ANYWHERE NEAR SPECIFIC.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* ISOL -SHRA WITH A MINIMAL CHANCE OF TSRA.

JEE

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE IS OVER THE REGION WITH MANY SITES INDICATING CALM
WINDS AND THE EARLY STAGES OF FOG DEVELOPMENT. EXPECTING FOG TO BE
THE WORST AT GYY WITH IFR FOG PSBL. DPA WILL ALSO SEE MVFR FOG.
FOG WILL QUICKLY BURN OFF THIS MORNING WITH AMPLE MIXING EXPECTED.
WEST WINDS WILL BE 10-15 KT WITH OCNL GUSTS PSBL. THE STRONG FLOW
WILL KEEP THE LAKE BREEZE ALONG THE SHORELINE. ISOL SHRA ARE
EXPECTED TO FORM ALONG THE LAKE BREEZE AND NORTHERN IL. CONFIDENCE
IS MEDIUM IN LOCATION AND COVERAGE SO BACKED OFF ON PRECIP BY
REPLACING THE VCSH WITH A PROB30. STABILITY WILL LIMIT TSRA
DEVELOPMENT AS WELL. SHOWERS DISSIPATE THIS EVENING AND LIGHT SW
WINDS ARE EXPECTED OVERNIGHT.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* MEDIUM CONFIDENCE IN SHRA COVERAGE AND LOCATION.

* MEDIUM-HIGH CONFIDENCE IN A VERY VERY LOW CHANCE OF TSRA
  DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY AND SATURDAY...AFTERNOON ISOLATED SHRA/TSRA. AFTERNOON
  LAKE BREEZES.
* SUNDAY AND MONDAY...DRY/VFR.
* TUESDAY...CHANCE OF TSRA.

&&

.MARINE...
257 AM CDT

BROAD HIGH PRESSURE IS OVER THE REGION WITH A WEAK LOW OVER JAMES
BAY.  SOUTHWEST 10-15KT WINDS WILL BECOME SOUTH THIS AFTERNOON. MAY
SEE PATCHY FOG FORM OVER THE LAKE AGAIN...BUT WITH SHOWERS...A FEW
STORMS...AND DECENT FLOW...DECIDED TO KEEP PATCHY FOG OUT OF THE
GRIDS FOR NOW. IF FOG DOES FORM...IT WOULD BE IN THE AFTERNOON
THROUGH THE EVENING. A WEAK COLD FRONT WILL MOVE DOWN THE NORTH HALF
OF THE LAKE TONIGHT WITH WINDS BECOMING VARIABLE BEHIND IT. THE
SOUTH HALF WILL CONTINUE TO SEE SOUTHWEST WINDS. THE FRONT WILL
DISSIPATE OVER THE LAKE EARLY FRIDAY.

A CONTINUED LIGHT PRESSURE GRADIENT OVER THE LAKE THROUGH MONDAY
WILL MEAN SPEEDS LESS THAN 15 KT AND EVEN BEING VARIABLE AT
TIMES...WITH AFTERNOON LAKE BREEZES IN NEARSHORE AREAS. FRIDAY LOOKS
TO BE A DAY SIMILAR TO THIS PAST TUESDAY...WITH SCATTERED STORMS OF
OVER CENTRAL WI TO NORTHERN IL...SOME OF WHICH COULD BE GUSTY AND
TRAVERSE INTO THE WESTERN NEARSHORE AREAS WHERE STABILITY IS NOT
AS HIGH. SO WHILE GENERALLY TRANQUIL CONDITIONS THE NEXT SEVERAL
DAYS...THAT IS SOMETHING FOR MARINERS IN THE NEARSHORE TO BE AWARE
OF.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 310858
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
358 AM CDT THU JUL 31 2014

.DISCUSSION...
257 AM CDT

SYNOPSIS...ROUNDS OF AFTERNOON SHOWERS AND THUNDERSTORMS WILL
CONTINUE THROUGH THE END OF THE WEEK.  MINIMAL CHANCES OF THUNDER
TODAY...BUT HIGHER CHANCES LOOK TO ARRIVE TOMORROW AND SATURDAY.
TEMPERATURES REMAIN AROUND 80 THROUGH THE WEEKEND EXCEPT FOR ALONG
THE LAKE WHERE LAKE BREEZES WILL KEEP HIGHS IN THE 70S TOMORROW
THROUGH THE WEEKEND. A BRIEF WARM UP INTO THE MID 80S IS EXPECTED
EARLY NEXT WEEK.

TODAY AND TONIGHT...
PREPARE FOR A VERY FAMILIAR SONG AND DANCE...BROAD HIGH PRESSURE IS
OVER THE REGION WITH LIGHT FLOW AND PATCHY FOG. THE FOG WILL BURN
OFF QUICKLY THIS MORNING AS MIXING GETS GOING. LOOKING AT A BREEZY
DAY WITH WEST WINDS AT 10-15 KT. A LAKE BREEZE WILL FORM...BUT
EXPECTING IT TO STAY JUST OFF SHORE AS WIND SPEEDS ARE AT 10+ KT
THROUGH THE COLUMN.

AN UPPER LEVEL VORT STREAMER APPROACHES FROM THE NORTHWEST TODAY.
THEREFORE...WEAK FORCING WILL BE OVER NORTHERN IL AND FAR NORTHERN
IN...SO HAVE ANOTHER ROUND OF ISOLATED TO SCATTERED SHOWERS IN THE
FORECAST. BASED ON YESTERDAYS LIMITED ACTIVITY...THINKING WE WILL
SEE FEW IF ANY THUNDERSTORMS. THE DVN SOUNDING FEATURED A CAP
AROUND 650MB YESTERDAY AND MODEL GUIDANCE HAS A SIMILAR CAP IN
STORE FOR US TODAY. THE BEST CHANCE FOR SHOWERS WILL BE NORTH OF
I-80. NOT EXPECTING MUCH PRECIP FROM ANY SHOWERS THAT DO FORM.

HIGH TEMPS WILL BE AROUND 80 AND OVERNIGHT LOWS WILL BE AROUND
60...EXCEPT FOR THE MID 60S DOWNTOWN. MAY SEE FOG AGAIN TOMORROW
NIGHT...BUT NOT OVERLY IMPRESSED SO LEFT FOG OUT OF THE FORECAST FOR
NOW.

JEE

FRIDAY...
THE UPPER PATTERN REMAINS THE SAME FOR ONE MORE DAY INTO FRIDAY WITH
THE FORECAST AREA REMAINING ON THE SOUTHWEST SIDE OF THE EASTERN
CANADIAN LONG WAVE TROUGH. ONE OR TWO SHORT WAVE IMPULSES ARE
PROJECTED TO MOVE AROUND THE TROUGH IN THE NORTHWEST FLOW ALOFT
DURING THE DAY AND EVENING ON FRIDAY...KEEPING 500MB AND 700MB
TEMPERATURES AT ONE TO TWO STANDARDIZED ANOMALIES BELOW NORMAL.
COMBINED WITH A LITTLE MORE LOW-LEVEL HEATING ON FRIDAY...THE
SLIGHT WARM TEMPERATURE NOSE/CAP NEAR 650MB YESTERDAY AND TODAY IS
EXPECTED TO BE OVERCOME BY THIS AND THUS FORECAST SOUNDINGS
PROVIDE 800 TO 1300 J/KG OF MLCAPE OVER SOUTHERN WI/NORTHERN IL
DESPITE FORECAST DEW POINTS ONLY IN THE UPPER 50S. OVERALL
COVERAGE OF STORMS IS EXPECTED TO BE HIGHER IN THE REGION THAN THE
PAST COUPLE DAYS BECAUSE OF THIS...MAYBE SIMILAR TO TUESDAY. A
FEW STRONGER UPDRAFTS AND ASSOCIATED GUSTY DOWNDRAFTS ARE POSSIBLE
IN THE REGION DURING MID- AFTERNOON THROUGH MID-EVE.

THIS WEEKEND...
HIGH PRESSURE...ALBEIT WEAK...IS FORECAST TO BUILD SOUTHEASTWARD
ACROSS THE REGION EARLY IN THE WEEKEND IN ASSOCIATION WITH HEIGHT
RISES ALOFT. A DEVELOPING WEAK COOL FRONT AHEAD OF THE HIGH LOOKS
TO BE A MODEST FOCUS FOR SCATTERED AFTERNOON SHOWERS/STORMS IN THE
LOWER GREAT LAKES REGION. THIS COULD BE PRIMARILY EAST OF THE
LOCAL AREA BASED ON SOME GUIDANCE...BUT GIVEN THE MODEL SPREAD AND
THE SUBTLE FEATURES THAT COULD SPARK SOME SHOWERS...FELT PRUDENT
TO KEEP CHANCE POPS DURING THE DAY. NORTHEAST FLOW IS ANTICIPATED
TO DEVELOP AND DEPENDING ON TIMING COULD PROVIDE A STRONGER LAKE
BREEZE WITH AFTERNOON COOLING IN LAKE ADJACENT COUNTIES. THE HIGH
LOOKS TO MAKE FOR A PLEASANT WEATHER SATURDAY NIGHT THROUGH THE
END OF THE WEEKEND.

MONDAY THROUGH WEDNESDAY...
THE UPPER FLOW WILL BE MORE DAMPENED AND THUS A LITTLE MORE
PROGRESSIVE. LONG RANGE ENSEMBLES AND FORECAST MODELS HAVE MODEST
AGREEMENT ON A JET MAXIMA TRAVERSING THE NORTHERN U.S. SOMETIME
MIDWEEK WITH AN ASSOCIATED WAVE IN THE MID-LEVELS AND A CLOSED
SURFACE LOW DEVELOPING IN THE PLAINS AND MOVING EASTWARD. GIVEN
THE DISTANCE THOUGH SEE LITTLE OPPORTUNITY TO IMPROVE MUCH FROM A
WELL-VERIFYING BLEND OF MODELS PROVIDING CHANCE POPS AREA-WIDE IN
THAT TIME PERIOD. WITH A CLOSED SURFACE LOW OF 1005 OR STRONGER ON
BOTH THE 31.00 GFS AND EC...CANT RULE OUT STRONGER STORMS IN THE
REGION BUT FAR TOO EARLY TO GET ANYWHERE NEAR SPECIFIC.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* ISOL -SHRA WITH A MINIMAL CHANCE OF TSRA.

JEE

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE IS OVER THE REGION WITH MANY SITES INDICATING CALM
WINDS AND THE EARLY STAGES OF FOG DEVELOPMENT. EXPECTING FOG TO BE
THE WORST AT GYY WITH IFR FOG PSBL. DPA WILL ALSO SEE MVFR FOG.
FOG WILL QUICKLY BURN OFF THIS MORNING WITH AMPLE MIXING EXPECTED.
WEST WINDS WILL BE 10-15 KT WITH OCNL GUSTS PSBL. THE STRONG FLOW
WILL KEEP THE LAKE BREEZE ALONG THE SHORELINE. ISOL SHRA ARE
EXPECTED TO FORM ALONG THE LAKE BREEZE AND NORTHERN IL. CONFIDENCE
IS MEDIUM IN LOCATION AND COVERAGE SO BACKED OFF ON PRECIP BY
REPLACING THE VCSH WITH A PROB30. STABILITY WILL LIMIT TSRA
DEVELOPMENT AS WELL. SHOWERS DISSIPATE THIS EVENING AND LIGHT SW
WINDS ARE EXPECTED OVERNIGHT.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* MEDIUM CONFIDENCE IN SHRA COVERAGE AND LOCATION.

* MEDIUM-HIGH CONFIDENCE IN A VERY VERY LOW CHANCE OF TSRA
  DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY AND SATURDAY...AFTERNOON ISOLATED SHRA/TSRA. AFTERNOON
  LAKE BREEZES.
* SUNDAY AND MONDAY...DRY/VFR.
* TUESDAY...CHANCE OF TSRA.

&&

.MARINE...
257 AM CDT

BROAD HIGH PRESSURE IS OVER THE REGION WITH A WEAK LOW OVER JAMES
BAY.  SOUTHWEST 10-15KT WINDS WILL BECOME SOUTH THIS AFTERNOON. MAY
SEE PATCHY FOG FORM OVER THE LAKE AGAIN...BUT WITH SHOWERS...A FEW
STORMS...AND DECENT FLOW...DECIDED TO KEEP PATCHY FOG OUT OF THE
GRIDS FOR NOW. IF FOG DOES FORM...IT WOULD BE IN THE AFTERNOON
THROUGH THE EVENING. A WEAK COLD FRONT WILL MOVE DOWN THE NORTH HALF
OF THE LAKE TONIGHT WITH WINDS BECOMING VARIABLE BEHIND IT. THE
SOUTH HALF WILL CONTINUE TO SEE SOUTHWEST WINDS. THE FRONT WILL
DISSIPATE OVER THE LAKE EARLY FRIDAY.

A CONTINUED LIGHT PRESSURE GRADIENT OVER THE LAKE THROUGH MONDAY
WILL MEAN SPEEDS LESS THAN 15 KT AND EVEN BEING VARIABLE AT
TIMES...WITH AFTERNOON LAKE BREEZES IN NEARSHORE AREAS. FRIDAY LOOKS
TO BE A DAY SIMILAR TO THIS PAST TUESDAY...WITH SCATTERED STORMS OF
OVER CENTRAL WI TO NORTHERN IL...SOME OF WHICH COULD BE GUSTY AND
TRAVERSE INTO THE WESTERN NEARSHORE AREAS WHERE STABILITY IS NOT
AS HIGH. SO WHILE GENERALLY TRANQUIL CONDITIONS THE NEXT SEVERAL
DAYS...THAT IS SOMETHING FOR MARINERS IN THE NEARSHORE TO BE AWARE
OF.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 310858
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
358 AM CDT THU JUL 31 2014

.DISCUSSION...
257 AM CDT

SYNOPSIS...ROUNDS OF AFTERNOON SHOWERS AND THUNDERSTORMS WILL
CONTINUE THROUGH THE END OF THE WEEK.  MINIMAL CHANCES OF THUNDER
TODAY...BUT HIGHER CHANCES LOOK TO ARRIVE TOMORROW AND SATURDAY.
TEMPERATURES REMAIN AROUND 80 THROUGH THE WEEKEND EXCEPT FOR ALONG
THE LAKE WHERE LAKE BREEZES WILL KEEP HIGHS IN THE 70S TOMORROW
THROUGH THE WEEKEND. A BRIEF WARM UP INTO THE MID 80S IS EXPECTED
EARLY NEXT WEEK.

TODAY AND TONIGHT...
PREPARE FOR A VERY FAMILIAR SONG AND DANCE...BROAD HIGH PRESSURE IS
OVER THE REGION WITH LIGHT FLOW AND PATCHY FOG. THE FOG WILL BURN
OFF QUICKLY THIS MORNING AS MIXING GETS GOING. LOOKING AT A BREEZY
DAY WITH WEST WINDS AT 10-15 KT. A LAKE BREEZE WILL FORM...BUT
EXPECTING IT TO STAY JUST OFF SHORE AS WIND SPEEDS ARE AT 10+ KT
THROUGH THE COLUMN.

AN UPPER LEVEL VORT STREAMER APPROACHES FROM THE NORTHWEST TODAY.
THEREFORE...WEAK FORCING WILL BE OVER NORTHERN IL AND FAR NORTHERN
IN...SO HAVE ANOTHER ROUND OF ISOLATED TO SCATTERED SHOWERS IN THE
FORECAST. BASED ON YESTERDAYS LIMITED ACTIVITY...THINKING WE WILL
SEE FEW IF ANY THUNDERSTORMS. THE DVN SOUNDING FEATURED A CAP
AROUND 650MB YESTERDAY AND MODEL GUIDANCE HAS A SIMILAR CAP IN
STORE FOR US TODAY. THE BEST CHANCE FOR SHOWERS WILL BE NORTH OF
I-80. NOT EXPECTING MUCH PRECIP FROM ANY SHOWERS THAT DO FORM.

HIGH TEMPS WILL BE AROUND 80 AND OVERNIGHT LOWS WILL BE AROUND
60...EXCEPT FOR THE MID 60S DOWNTOWN. MAY SEE FOG AGAIN TOMORROW
NIGHT...BUT NOT OVERLY IMPRESSED SO LEFT FOG OUT OF THE FORECAST FOR
NOW.

JEE

FRIDAY...
THE UPPER PATTERN REMAINS THE SAME FOR ONE MORE DAY INTO FRIDAY WITH
THE FORECAST AREA REMAINING ON THE SOUTHWEST SIDE OF THE EASTERN
CANADIAN LONG WAVE TROUGH. ONE OR TWO SHORT WAVE IMPULSES ARE
PROJECTED TO MOVE AROUND THE TROUGH IN THE NORTHWEST FLOW ALOFT
DURING THE DAY AND EVENING ON FRIDAY...KEEPING 500MB AND 700MB
TEMPERATURES AT ONE TO TWO STANDARDIZED ANOMALIES BELOW NORMAL.
COMBINED WITH A LITTLE MORE LOW-LEVEL HEATING ON FRIDAY...THE
SLIGHT WARM TEMPERATURE NOSE/CAP NEAR 650MB YESTERDAY AND TODAY IS
EXPECTED TO BE OVERCOME BY THIS AND THUS FORECAST SOUNDINGS
PROVIDE 800 TO 1300 J/KG OF MLCAPE OVER SOUTHERN WI/NORTHERN IL
DESPITE FORECAST DEW POINTS ONLY IN THE UPPER 50S. OVERALL
COVERAGE OF STORMS IS EXPECTED TO BE HIGHER IN THE REGION THAN THE
PAST COUPLE DAYS BECAUSE OF THIS...MAYBE SIMILAR TO TUESDAY. A
FEW STRONGER UPDRAFTS AND ASSOCIATED GUSTY DOWNDRAFTS ARE POSSIBLE
IN THE REGION DURING MID- AFTERNOON THROUGH MID-EVE.

THIS WEEKEND...
HIGH PRESSURE...ALBEIT WEAK...IS FORECAST TO BUILD SOUTHEASTWARD
ACROSS THE REGION EARLY IN THE WEEKEND IN ASSOCIATION WITH HEIGHT
RISES ALOFT. A DEVELOPING WEAK COOL FRONT AHEAD OF THE HIGH LOOKS
TO BE A MODEST FOCUS FOR SCATTERED AFTERNOON SHOWERS/STORMS IN THE
LOWER GREAT LAKES REGION. THIS COULD BE PRIMARILY EAST OF THE
LOCAL AREA BASED ON SOME GUIDANCE...BUT GIVEN THE MODEL SPREAD AND
THE SUBTLE FEATURES THAT COULD SPARK SOME SHOWERS...FELT PRUDENT
TO KEEP CHANCE POPS DURING THE DAY. NORTHEAST FLOW IS ANTICIPATED
TO DEVELOP AND DEPENDING ON TIMING COULD PROVIDE A STRONGER LAKE
BREEZE WITH AFTERNOON COOLING IN LAKE ADJACENT COUNTIES. THE HIGH
LOOKS TO MAKE FOR A PLEASANT WEATHER SATURDAY NIGHT THROUGH THE
END OF THE WEEKEND.

MONDAY THROUGH WEDNESDAY...
THE UPPER FLOW WILL BE MORE DAMPENED AND THUS A LITTLE MORE
PROGRESSIVE. LONG RANGE ENSEMBLES AND FORECAST MODELS HAVE MODEST
AGREEMENT ON A JET MAXIMA TRAVERSING THE NORTHERN U.S. SOMETIME
MIDWEEK WITH AN ASSOCIATED WAVE IN THE MID-LEVELS AND A CLOSED
SURFACE LOW DEVELOPING IN THE PLAINS AND MOVING EASTWARD. GIVEN
THE DISTANCE THOUGH SEE LITTLE OPPORTUNITY TO IMPROVE MUCH FROM A
WELL-VERIFYING BLEND OF MODELS PROVIDING CHANCE POPS AREA-WIDE IN
THAT TIME PERIOD. WITH A CLOSED SURFACE LOW OF 1005 OR STRONGER ON
BOTH THE 31.00 GFS AND EC...CANT RULE OUT STRONGER STORMS IN THE
REGION BUT FAR TOO EARLY TO GET ANYWHERE NEAR SPECIFIC.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* ISOL -SHRA WITH A MINIMAL CHANCE OF TSRA.

JEE

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE IS OVER THE REGION WITH MANY SITES INDICATING CALM
WINDS AND THE EARLY STAGES OF FOG DEVELOPMENT. EXPECTING FOG TO BE
THE WORST AT GYY WITH IFR FOG PSBL. DPA WILL ALSO SEE MVFR FOG.
FOG WILL QUICKLY BURN OFF THIS MORNING WITH AMPLE MIXING EXPECTED.
WEST WINDS WILL BE 10-15 KT WITH OCNL GUSTS PSBL. THE STRONG FLOW
WILL KEEP THE LAKE BREEZE ALONG THE SHORELINE. ISOL SHRA ARE
EXPECTED TO FORM ALONG THE LAKE BREEZE AND NORTHERN IL. CONFIDENCE
IS MEDIUM IN LOCATION AND COVERAGE SO BACKED OFF ON PRECIP BY
REPLACING THE VCSH WITH A PROB30. STABILITY WILL LIMIT TSRA
DEVELOPMENT AS WELL. SHOWERS DISSIPATE THIS EVENING AND LIGHT SW
WINDS ARE EXPECTED OVERNIGHT.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* MEDIUM CONFIDENCE IN SHRA COVERAGE AND LOCATION.

* MEDIUM-HIGH CONFIDENCE IN A VERY VERY LOW CHANCE OF TSRA
  DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY AND SATURDAY...AFTERNOON ISOLATED SHRA/TSRA. AFTERNOON
  LAKE BREEZES.
* SUNDAY AND MONDAY...DRY/VFR.
* TUESDAY...CHANCE OF TSRA.

&&

.MARINE...
257 AM CDT

BROAD HIGH PRESSURE IS OVER THE REGION WITH A WEAK LOW OVER JAMES
BAY.  SOUTHWEST 10-15KT WINDS WILL BECOME SOUTH THIS AFTERNOON. MAY
SEE PATCHY FOG FORM OVER THE LAKE AGAIN...BUT WITH SHOWERS...A FEW
STORMS...AND DECENT FLOW...DECIDED TO KEEP PATCHY FOG OUT OF THE
GRIDS FOR NOW. IF FOG DOES FORM...IT WOULD BE IN THE AFTERNOON
THROUGH THE EVENING. A WEAK COLD FRONT WILL MOVE DOWN THE NORTH HALF
OF THE LAKE TONIGHT WITH WINDS BECOMING VARIABLE BEHIND IT. THE
SOUTH HALF WILL CONTINUE TO SEE SOUTHWEST WINDS. THE FRONT WILL
DISSIPATE OVER THE LAKE EARLY FRIDAY.

A CONTINUED LIGHT PRESSURE GRADIENT OVER THE LAKE THROUGH MONDAY
WILL MEAN SPEEDS LESS THAN 15 KT AND EVEN BEING VARIABLE AT
TIMES...WITH AFTERNOON LAKE BREEZES IN NEARSHORE AREAS. FRIDAY LOOKS
TO BE A DAY SIMILAR TO THIS PAST TUESDAY...WITH SCATTERED STORMS OF
OVER CENTRAL WI TO NORTHERN IL...SOME OF WHICH COULD BE GUSTY AND
TRAVERSE INTO THE WESTERN NEARSHORE AREAS WHERE STABILITY IS NOT
AS HIGH. SO WHILE GENERALLY TRANQUIL CONDITIONS THE NEXT SEVERAL
DAYS...THAT IS SOMETHING FOR MARINERS IN THE NEARSHORE TO BE AWARE
OF.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 310858
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
358 AM CDT THU JUL 31 2014

.DISCUSSION...
257 AM CDT

SYNOPSIS...ROUNDS OF AFTERNOON SHOWERS AND THUNDERSTORMS WILL
CONTINUE THROUGH THE END OF THE WEEK.  MINIMAL CHANCES OF THUNDER
TODAY...BUT HIGHER CHANCES LOOK TO ARRIVE TOMORROW AND SATURDAY.
TEMPERATURES REMAIN AROUND 80 THROUGH THE WEEKEND EXCEPT FOR ALONG
THE LAKE WHERE LAKE BREEZES WILL KEEP HIGHS IN THE 70S TOMORROW
THROUGH THE WEEKEND. A BRIEF WARM UP INTO THE MID 80S IS EXPECTED
EARLY NEXT WEEK.

TODAY AND TONIGHT...
PREPARE FOR A VERY FAMILIAR SONG AND DANCE...BROAD HIGH PRESSURE IS
OVER THE REGION WITH LIGHT FLOW AND PATCHY FOG. THE FOG WILL BURN
OFF QUICKLY THIS MORNING AS MIXING GETS GOING. LOOKING AT A BREEZY
DAY WITH WEST WINDS AT 10-15 KT. A LAKE BREEZE WILL FORM...BUT
EXPECTING IT TO STAY JUST OFF SHORE AS WIND SPEEDS ARE AT 10+ KT
THROUGH THE COLUMN.

AN UPPER LEVEL VORT STREAMER APPROACHES FROM THE NORTHWEST TODAY.
THEREFORE...WEAK FORCING WILL BE OVER NORTHERN IL AND FAR NORTHERN
IN...SO HAVE ANOTHER ROUND OF ISOLATED TO SCATTERED SHOWERS IN THE
FORECAST. BASED ON YESTERDAYS LIMITED ACTIVITY...THINKING WE WILL
SEE FEW IF ANY THUNDERSTORMS. THE DVN SOUNDING FEATURED A CAP
AROUND 650MB YESTERDAY AND MODEL GUIDANCE HAS A SIMILAR CAP IN
STORE FOR US TODAY. THE BEST CHANCE FOR SHOWERS WILL BE NORTH OF
I-80. NOT EXPECTING MUCH PRECIP FROM ANY SHOWERS THAT DO FORM.

HIGH TEMPS WILL BE AROUND 80 AND OVERNIGHT LOWS WILL BE AROUND
60...EXCEPT FOR THE MID 60S DOWNTOWN. MAY SEE FOG AGAIN TOMORROW
NIGHT...BUT NOT OVERLY IMPRESSED SO LEFT FOG OUT OF THE FORECAST FOR
NOW.

JEE

FRIDAY...
THE UPPER PATTERN REMAINS THE SAME FOR ONE MORE DAY INTO FRIDAY WITH
THE FORECAST AREA REMAINING ON THE SOUTHWEST SIDE OF THE EASTERN
CANADIAN LONG WAVE TROUGH. ONE OR TWO SHORT WAVE IMPULSES ARE
PROJECTED TO MOVE AROUND THE TROUGH IN THE NORTHWEST FLOW ALOFT
DURING THE DAY AND EVENING ON FRIDAY...KEEPING 500MB AND 700MB
TEMPERATURES AT ONE TO TWO STANDARDIZED ANOMALIES BELOW NORMAL.
COMBINED WITH A LITTLE MORE LOW-LEVEL HEATING ON FRIDAY...THE
SLIGHT WARM TEMPERATURE NOSE/CAP NEAR 650MB YESTERDAY AND TODAY IS
EXPECTED TO BE OVERCOME BY THIS AND THUS FORECAST SOUNDINGS
PROVIDE 800 TO 1300 J/KG OF MLCAPE OVER SOUTHERN WI/NORTHERN IL
DESPITE FORECAST DEW POINTS ONLY IN THE UPPER 50S. OVERALL
COVERAGE OF STORMS IS EXPECTED TO BE HIGHER IN THE REGION THAN THE
PAST COUPLE DAYS BECAUSE OF THIS...MAYBE SIMILAR TO TUESDAY. A
FEW STRONGER UPDRAFTS AND ASSOCIATED GUSTY DOWNDRAFTS ARE POSSIBLE
IN THE REGION DURING MID- AFTERNOON THROUGH MID-EVE.

THIS WEEKEND...
HIGH PRESSURE...ALBEIT WEAK...IS FORECAST TO BUILD SOUTHEASTWARD
ACROSS THE REGION EARLY IN THE WEEKEND IN ASSOCIATION WITH HEIGHT
RISES ALOFT. A DEVELOPING WEAK COOL FRONT AHEAD OF THE HIGH LOOKS
TO BE A MODEST FOCUS FOR SCATTERED AFTERNOON SHOWERS/STORMS IN THE
LOWER GREAT LAKES REGION. THIS COULD BE PRIMARILY EAST OF THE
LOCAL AREA BASED ON SOME GUIDANCE...BUT GIVEN THE MODEL SPREAD AND
THE SUBTLE FEATURES THAT COULD SPARK SOME SHOWERS...FELT PRUDENT
TO KEEP CHANCE POPS DURING THE DAY. NORTHEAST FLOW IS ANTICIPATED
TO DEVELOP AND DEPENDING ON TIMING COULD PROVIDE A STRONGER LAKE
BREEZE WITH AFTERNOON COOLING IN LAKE ADJACENT COUNTIES. THE HIGH
LOOKS TO MAKE FOR A PLEASANT WEATHER SATURDAY NIGHT THROUGH THE
END OF THE WEEKEND.

MONDAY THROUGH WEDNESDAY...
THE UPPER FLOW WILL BE MORE DAMPENED AND THUS A LITTLE MORE
PROGRESSIVE. LONG RANGE ENSEMBLES AND FORECAST MODELS HAVE MODEST
AGREEMENT ON A JET MAXIMA TRAVERSING THE NORTHERN U.S. SOMETIME
MIDWEEK WITH AN ASSOCIATED WAVE IN THE MID-LEVELS AND A CLOSED
SURFACE LOW DEVELOPING IN THE PLAINS AND MOVING EASTWARD. GIVEN
THE DISTANCE THOUGH SEE LITTLE OPPORTUNITY TO IMPROVE MUCH FROM A
WELL-VERIFYING BLEND OF MODELS PROVIDING CHANCE POPS AREA-WIDE IN
THAT TIME PERIOD. WITH A CLOSED SURFACE LOW OF 1005 OR STRONGER ON
BOTH THE 31.00 GFS AND EC...CANT RULE OUT STRONGER STORMS IN THE
REGION BUT FAR TOO EARLY TO GET ANYWHERE NEAR SPECIFIC.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* ISOL -SHRA WITH A MINIMAL CHANCE OF TSRA.

JEE

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE IS OVER THE REGION WITH MANY SITES INDICATING CALM
WINDS AND THE EARLY STAGES OF FOG DEVELOPMENT. EXPECTING FOG TO BE
THE WORST AT GYY WITH IFR FOG PSBL. DPA WILL ALSO SEE MVFR FOG.
FOG WILL QUICKLY BURN OFF THIS MORNING WITH AMPLE MIXING EXPECTED.
WEST WINDS WILL BE 10-15 KT WITH OCNL GUSTS PSBL. THE STRONG FLOW
WILL KEEP THE LAKE BREEZE ALONG THE SHORELINE. ISOL SHRA ARE
EXPECTED TO FORM ALONG THE LAKE BREEZE AND NORTHERN IL. CONFIDENCE
IS MEDIUM IN LOCATION AND COVERAGE SO BACKED OFF ON PRECIP BY
REPLACING THE VCSH WITH A PROB30. STABILITY WILL LIMIT TSRA
DEVELOPMENT AS WELL. SHOWERS DISSIPATE THIS EVENING AND LIGHT SW
WINDS ARE EXPECTED OVERNIGHT.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* MEDIUM CONFIDENCE IN SHRA COVERAGE AND LOCATION.

* MEDIUM-HIGH CONFIDENCE IN A VERY VERY LOW CHANCE OF TSRA
  DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY AND SATURDAY...AFTERNOON ISOLATED SHRA/TSRA. AFTERNOON
  LAKE BREEZES.
* SUNDAY AND MONDAY...DRY/VFR.
* TUESDAY...CHANCE OF TSRA.

&&

.MARINE...
257 AM CDT

BROAD HIGH PRESSURE IS OVER THE REGION WITH A WEAK LOW OVER JAMES
BAY.  SOUTHWEST 10-15KT WINDS WILL BECOME SOUTH THIS AFTERNOON. MAY
SEE PATCHY FOG FORM OVER THE LAKE AGAIN...BUT WITH SHOWERS...A FEW
STORMS...AND DECENT FLOW...DECIDED TO KEEP PATCHY FOG OUT OF THE
GRIDS FOR NOW. IF FOG DOES FORM...IT WOULD BE IN THE AFTERNOON
THROUGH THE EVENING. A WEAK COLD FRONT WILL MOVE DOWN THE NORTH HALF
OF THE LAKE TONIGHT WITH WINDS BECOMING VARIABLE BEHIND IT. THE
SOUTH HALF WILL CONTINUE TO SEE SOUTHWEST WINDS. THE FRONT WILL
DISSIPATE OVER THE LAKE EARLY FRIDAY.

A CONTINUED LIGHT PRESSURE GRADIENT OVER THE LAKE THROUGH MONDAY
WILL MEAN SPEEDS LESS THAN 15 KT AND EVEN BEING VARIABLE AT
TIMES...WITH AFTERNOON LAKE BREEZES IN NEARSHORE AREAS. FRIDAY LOOKS
TO BE A DAY SIMILAR TO THIS PAST TUESDAY...WITH SCATTERED STORMS OF
OVER CENTRAL WI TO NORTHERN IL...SOME OF WHICH COULD BE GUSTY AND
TRAVERSE INTO THE WESTERN NEARSHORE AREAS WHERE STABILITY IS NOT
AS HIGH. SO WHILE GENERALLY TRANQUIL CONDITIONS THE NEXT SEVERAL
DAYS...THAT IS SOMETHING FOR MARINERS IN THE NEARSHORE TO BE AWARE
OF.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KILX 310834
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
334 AM CDT Thu Jul 31 2014

.DISCUSSION...
ISSUED 311 AM CDT Thu Jul 31 2014
Very little changing in this forecast. Deep low over southeastern
Canada keeping the eastern half of the country dominated by the
500mb trof. Northwesterly flow over the Plains and into the
Midwest. Ridging over the west building up some warm air that will
start to edge towards the region by the end of the forecast
period. Diurnal element to cloud cover and some shower activity
possible to the northeast today...and a series of waves diving
into and around the upper trof will bring better chances for
scattered showers/thunderstorms for Friday and Saturday. Watching
forecast soundings for tomorrows potential thunderstorms and
severe weather chances. Forecast drying out for the latter half of
the weekend and into Monday until another wave moves on the
western coast, kicking the eastern trof out of the stagnant
pattern. A more progressive series of waves begins to drive better
rain chances for the remainder of the forecast.

SHORT TERM...Today and tomorrow...
Mild again today with light winds, just below normal max temps.
Sunshine and afternoon clouds with some of the heavier clouds to
the northeast possibly providing a sparse shower. Tomorrow,
chances improve with a wave diving into the trof and enhancing the
afternoon instability. Wind profiles very weak, but lower freezing
level and pretty good lapse rates tomorrow afternoon could result
in some good updrafts should thunderstorms develop. SPC has put
the area in a see text for marginal hail threat with the daytime
heating/shortwave thunderstorms  in the afternoon.

LONG TERM...Saturday through Tuesday...
Models beginning to send another wave into the trof for Saturday,
with almost a repeat of Friday with similar forecast soundings.
Beginning to trend the forecast to scattered showers and
thunderstorms for Saturday as well should the signal continue.
Though the thunderstorm development will be countered by
increasing subsidence with ridge moving closer to the area. High
pressure dominating remains of weekend as the sfc ridge axis moves
into the region. Winds remain light and variable and dry forecast
as the upper trof finally starts to progress across into the NE.
Chances for more significant weather starting to return Tues/Wed
as a more active and progressive flow sets up across the country.

HJS
&&

.AVIATION...
ISSUED 1128 PM CDT Wed Jul 30 2014

Not much needs to be changed with the previous TAF set.
Light/variable winds overnight to become more westerly for a time
late Thursday morning into the afternoon, then light/variable
again in the evening. Have a bit of concern with potential for
light shallow fog toward sunrise, though this would have no
substantial depth as the forecast soundings show dry conditions in
the lower levels. Will leave this out for now and continue to
monitor.

Geelhart
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$







000
FXUS63 KILX 310834
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
334 AM CDT Thu Jul 31 2014

.DISCUSSION...
ISSUED 311 AM CDT Thu Jul 31 2014
Very little changing in this forecast. Deep low over southeastern
Canada keeping the eastern half of the country dominated by the
500mb trof. Northwesterly flow over the Plains and into the
Midwest. Ridging over the west building up some warm air that will
start to edge towards the region by the end of the forecast
period. Diurnal element to cloud cover and some shower activity
possible to the northeast today...and a series of waves diving
into and around the upper trof will bring better chances for
scattered showers/thunderstorms for Friday and Saturday. Watching
forecast soundings for tomorrows potential thunderstorms and
severe weather chances. Forecast drying out for the latter half of
the weekend and into Monday until another wave moves on the
western coast, kicking the eastern trof out of the stagnant
pattern. A more progressive series of waves begins to drive better
rain chances for the remainder of the forecast.

SHORT TERM...Today and tomorrow...
Mild again today with light winds, just below normal max temps.
Sunshine and afternoon clouds with some of the heavier clouds to
the northeast possibly providing a sparse shower. Tomorrow,
chances improve with a wave diving into the trof and enhancing the
afternoon instability. Wind profiles very weak, but lower freezing
level and pretty good lapse rates tomorrow afternoon could result
in some good updrafts should thunderstorms develop. SPC has put
the area in a see text for marginal hail threat with the daytime
heating/shortwave thunderstorms  in the afternoon.

LONG TERM...Saturday through Tuesday...
Models beginning to send another wave into the trof for Saturday,
with almost a repeat of Friday with similar forecast soundings.
Beginning to trend the forecast to scattered showers and
thunderstorms for Saturday as well should the signal continue.
Though the thunderstorm development will be countered by
increasing subsidence with ridge moving closer to the area. High
pressure dominating remains of weekend as the sfc ridge axis moves
into the region. Winds remain light and variable and dry forecast
as the upper trof finally starts to progress across into the NE.
Chances for more significant weather starting to return Tues/Wed
as a more active and progressive flow sets up across the country.

HJS
&&

.AVIATION...
ISSUED 1128 PM CDT Wed Jul 30 2014

Not much needs to be changed with the previous TAF set.
Light/variable winds overnight to become more westerly for a time
late Thursday morning into the afternoon, then light/variable
again in the evening. Have a bit of concern with potential for
light shallow fog toward sunrise, though this would have no
substantial depth as the forecast soundings show dry conditions in
the lower levels. Will leave this out for now and continue to
monitor.

Geelhart
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 310805
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
305 AM CDT THU JUL 31 2014

.DISCUSSION...
257 AM CDT

SYNOPSIS...ROUNDS OF AFTERNOON SHOWERS AND THUNDERSTORMS WILL
CONTINUE THROUGH THE END OF THE WEEK.  MINIMAL CHANCES OF THUNDER
TODAY...BUT HIGHER CHANCES LOOK TO ARRIVE TOMORROW AND SATURDAY.
TEMPERATURES REMAIN AROUND 80 THROUGH THE WEEKEND EXCEPT FOR ALONG
THE LAKE WHERE LAKE BREEZES WILL KEEP HIGHS IN THE 70S TOMORROW
THROUGH THE WEEKEND. A BRIEF WARM UP INTO THE MID 80S IS EXPECTED
EARLY NEXT WEEK.

TODAY AND TONIGHT...
PREPARE FOR A VERY FAMILIAR SONG AND DANCE...BROAD HIGH PRESSURE IS
OVER THE REGION WITH LIGHT FLOW AND PATCHY FOG. THE FOG WILL BURN
OFF QUICKLY THIS MORNING AS MIXING GETS GOING. LOOKING AT A BREEZY
DAY WITH WEST WINDS AT 10-15 KT. A LAKE BREEZE WILL FORM...BUT
EXPECTING IT TO STAY JUST OFF SHORE AS WIND SPEEDS ARE AT 10+ KT
THROUGH THE COLUMN.

AN UPPER LEVEL VORT STREAMER APPROACHES FROM THE NORTHWEST TODAY.
THEREFORE...WEAK FORCING WILL BE OVER NORTHERN IL AND FAR NORTHERN
IN...SO HAVE ANOTHER ROUND OF ISOLATED TO SCATTERED SHOWERS IN THE
FORECAST. BASED ON YESTERDAYS LIMITED ACTIVITY...THINKING WE WILL
SEE FEW IF ANY THUNDERSTORMS. THE DVN SOUNDING FEATURED A CAP
AROUND 650MB YESTERDAY AND MODEL GUIDANCE HAS A SIMILAR CAP IN
STORE FOR US TODAY. THE BEST CHANCE FOR SHOWERS WILL BE NORTH OF
I-80. NOT EXPECTING MUCH PRECIP FROM ANY SHOWERS THAT DO FORM.

HIGH TEMPS WILL BE AROUND 80 AND OVERNIGHT LOWS WILL BE AROUND
60...EXCEPT FOR THE MID 60S DOWNTOWN. MAY SEE FOG AGAIN TOMORROW
NIGHT...BUT NOT OVERLY IMPRESSED SO LEFT FOG OUT OF THE FORECAST FOR
NOW.

JEE

FRIDAY...
THE UPPER PATTERN REMAINS THE SAME FOR ONE MORE DAY INTO FRIDAY WITH
THE FORECAST AREA REMAINING ON THE SOUTHWEST SIDE OF THE EASTERN
CANADIAN LONG WAVE TROUGH. ONE OR TWO SHORT WAVE IMPULSES ARE
PROJECTED TO MOVE AROUND THE TROUGH IN THE NORTHWEST FLOW ALOFT
DURING THE DAY AND EVENING ON FRIDAY...KEEPING 500MB AND 700MB
TEMPERATURES AT ONE TO TWO STANDARDIZED ANOMALIES BELOW NORMAL.
COMBINED WITH A LITTLE MORE LOW-LEVEL HEATING ON FRIDAY...THE
SLIGHT WARM TEMPERATURE NOSE/CAP NEAR 650MB YESTERDAY AND TODAY IS
EXPECTED TO BE OVERCOME BY THIS AND THUS FORECAST SOUNDINGS
PROVIDE 800 TO 1300 J/KG OF MLCAPE OVER SOUTHERN WI/NORTHERN IL
DESPITE FORECAST DEW POINTS ONLY IN THE UPPER 50S. OVERALL
COVERAGE OF STORMS IS EXPECTED TO BE HIGHER IN THE REGION THAN THE
PAST COUPLE DAYS BECAUSE OF THIS...MAYBE SIMILAR TO TUESDAY. A
FEW STRONGER UPDRAFTS AND ASSOCIATED GUSTY DOWNDRAFTS ARE POSSIBLE
IN THE REGION DURING MID- AFTERNOON THROUGH MID-EVE.

THIS WEEKEND...
HIGH PRESSURE...ALBEIT WEAK...IS FORECAST TO BUILD SOUTHEASTWARD
ACROSS THE REGION EARLY IN THE WEEKEND IN ASSOCIATION WITH HEIGHT
RISES ALOFT. A DEVELOPING WEAK COOL FRONT AHEAD OF THE HIGH LOOKS
TO BE A MODEST FOCUS FOR SCATTERED AFTERNOON SHOWERS/STORMS IN THE
LOWER GREAT LAKES REGION. THIS COULD BE PRIMARILY EAST OF THE
LOCAL AREA BASED ON SOME GUIDANCE...BUT GIVEN THE MODEL SPREAD AND
THE SUBTLE FEATURES THAT COULD SPARK SOME SHOWERS...FELT PRUDENT
TO KEEP CHANCE POPS DURING THE DAY. NORTHEAST FLOW IS ANTICIPATED
TO DEVELOP AND DEPENDING ON TIMING COULD PROVIDE A STRONGER LAKE
BREEZE WITH AFTERNOON COOLING IN LAKE ADJACENT COUNTIES. THE HIGH
LOOKS TO MAKE FOR A PLEASANT WEATHER SATURDAY NIGHT THROUGH THE
END OF THE WEEKEND.

MONDAY THROUGH WEDNESDAY...
THE UPPER FLOW WILL BE MORE DAMPENED AND THUS A LITTLE MORE
PROGRESSIVE. LONG RANGE ENSEMBLES AND FORECAST MODELS HAVE MODEST
AGREEMENT ON A JET MAXIMA TRAVERSING THE NORTHERN U.S. SOMETIME
MIDWEEK WITH AN ASSOCIATED WAVE IN THE MID-LEVELS AND A CLOSED
SURFACE LOW DEVELOPING IN THE PLAINS AND MOVING EASTWARD. GIVEN
THE DISTANCE THOUGH SEE LITTLE OPPORTUNITY TO IMPROVE MUCH FROM A
WELL-VERIFYING BLEND OF MODELS PROVIDING CHANCE POPS AREA-WIDE IN
THAT TIME PERIOD. WITH A CLOSED SURFACE LOW OF 1005 OR STRONGER ON
BOTH THE 31.00 GFS AND EC...CANT RULE OUT STRONGER STORMS IN THE
REGION BUT FAR TOO EARLY TO GET ANYWHERE NEAR SPECIFIC.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* ISOL -SHRA WITH A MINIMAL CHANCE OF TSRA.

JEE

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE IS OVER THE REGION WITH MANY SITES INDICATING CALM
WINDS AND THE EARLY STAGES OF FOG DEVELOPMENT. EXPECTING FOG TO BE
THE WORST AT GYY WITH IFR FOG PSBL. DPA WILL ALSO SEE MVFR FOG.
FOG WILL QUICKLY BURN OFF THIS MORNING WITH AMPLE MIXING EXPECTED.
WEST WINDS WILL BE 10-15 KT WITH OCNL GUSTS PSBL. THE STRONG FLOW
WILL KEEP THE LAKE BREEZE ALONG THE SHORELINE. ISOL SHRA ARE
EXPECTED TO FORM ALONG THE LAKE BREEZE AND NORTHERN IL. CONFIDENCE
IS MEDIUM IN LOCATION AND COVERAGE SO BACKED OFF ON PRECIP BY
REPLACING THE VCSH WITH A PROB30. STABILITY WILL LIMIT TSRA
DEVELOPMENT AS WELL. SHOWERS DISSIPATE THIS EVENING AND LIGHT SW
WINDS ARE EXPECTED OVERNIGHT.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM CONFIDENCE IN SHRA COVERAGE AND LOCATION.

* MEDIUM CONFIDENCE IN A VERY VERY LOW CHANCE OF TSRA DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY AND SATURDAY...AFTERNOON ISOLATED SHRA/TSRA. AFTERNOON
  LAKE BREEZES.
* SUNDAY AND MONDAY...DRY/VFR.
* TUESDAY...CHANCE OF TSRA.

&&

.MARINE...
257 AM CDT

BROAD HIGH PRESSURE IS OVER THE REGION WITH A WEAK LOW OVER JAMES
BAY.  SOUTHWEST 10-15KT WINDS WILL BECOME SOUTH THIS AFTERNOON. MAY
SEE PATCHY FOG FORM OVER THE LAKE AGAIN...BUT WITH SHOWERS...A FEW
STORMS...AND DECENT FLOW...DECIDED TO KEEP PATCHY FOG OUT OF THE
GRIDS FOR NOW. IF FOG DOES FORM...IT WOULD BE IN THE AFTERNOON
THROUGH THE EVENING. A WEAK COLD FRONT WILL MOVE DOWN THE NORTH HALF
OF THE LAKE TONIGHT WITH WINDS BECOMING VARIABLE BEHIND IT. THE
SOUTH HALF WILL CONTINUE TO SEE SOUTHWEST WINDS. THE FRONT WILL
DISSIPATE OVER THE LAKE EARLY FRIDAY.

A CONTINUED LIGHT PRESSURE GRADIENT OVER THE LAKE THROUGH MONDAY
WILL MEAN SPEEDS LESS THAN 15 KT AND EVEN BEING VARIABLE AT
TIMES...WITH AFTERNOON LAKE BREEZES IN NEARSHORE AREAS. FRIDAY LOOKS
TO BE A DAY SIMILAR TO THIS PAST TUESDAY...WITH SCATTERED STORMS OF
OVER CENTRAL WI TO NORTHERN IL...SOME OF WHICH COULD BE GUSTY AND
TRAVERSE INTO THE WESTERN NEARSHORE AREAS WHERE STABILITY IS NOT
AS HIGH. SO WHILE GENERALLY TRANQUIL CONDITIONS THE NEXT SEVERAL
DAYS...THAT IS SOMETHING FOR MARINERS IN THE NEARSHORE TO BE AWARE
OF.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO








000
FXUS63 KLOT 310805
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
305 AM CDT THU JUL 31 2014

.DISCUSSION...
257 AM CDT

SYNOPSIS...ROUNDS OF AFTERNOON SHOWERS AND THUNDERSTORMS WILL
CONTINUE THROUGH THE END OF THE WEEK.  MINIMAL CHANCES OF THUNDER
TODAY...BUT HIGHER CHANCES LOOK TO ARRIVE TOMORROW AND SATURDAY.
TEMPERATURES REMAIN AROUND 80 THROUGH THE WEEKEND EXCEPT FOR ALONG
THE LAKE WHERE LAKE BREEZES WILL KEEP HIGHS IN THE 70S TOMORROW
THROUGH THE WEEKEND. A BRIEF WARM UP INTO THE MID 80S IS EXPECTED
EARLY NEXT WEEK.

TODAY AND TONIGHT...
PREPARE FOR A VERY FAMILIAR SONG AND DANCE...BROAD HIGH PRESSURE IS
OVER THE REGION WITH LIGHT FLOW AND PATCHY FOG. THE FOG WILL BURN
OFF QUICKLY THIS MORNING AS MIXING GETS GOING. LOOKING AT A BREEZY
DAY WITH WEST WINDS AT 10-15 KT. A LAKE BREEZE WILL FORM...BUT
EXPECTING IT TO STAY JUST OFF SHORE AS WIND SPEEDS ARE AT 10+ KT
THROUGH THE COLUMN.

AN UPPER LEVEL VORT STREAMER APPROACHES FROM THE NORTHWEST TODAY.
THEREFORE...WEAK FORCING WILL BE OVER NORTHERN IL AND FAR NORTHERN
IN...SO HAVE ANOTHER ROUND OF ISOLATED TO SCATTERED SHOWERS IN THE
FORECAST. BASED ON YESTERDAYS LIMITED ACTIVITY...THINKING WE WILL
SEE FEW IF ANY THUNDERSTORMS. THE DVN SOUNDING FEATURED A CAP
AROUND 650MB YESTERDAY AND MODEL GUIDANCE HAS A SIMILAR CAP IN
STORE FOR US TODAY. THE BEST CHANCE FOR SHOWERS WILL BE NORTH OF
I-80. NOT EXPECTING MUCH PRECIP FROM ANY SHOWERS THAT DO FORM.

HIGH TEMPS WILL BE AROUND 80 AND OVERNIGHT LOWS WILL BE AROUND
60...EXCEPT FOR THE MID 60S DOWNTOWN. MAY SEE FOG AGAIN TOMORROW
NIGHT...BUT NOT OVERLY IMPRESSED SO LEFT FOG OUT OF THE FORECAST FOR
NOW.

JEE

FRIDAY...
THE UPPER PATTERN REMAINS THE SAME FOR ONE MORE DAY INTO FRIDAY WITH
THE FORECAST AREA REMAINING ON THE SOUTHWEST SIDE OF THE EASTERN
CANADIAN LONG WAVE TROUGH. ONE OR TWO SHORT WAVE IMPULSES ARE
PROJECTED TO MOVE AROUND THE TROUGH IN THE NORTHWEST FLOW ALOFT
DURING THE DAY AND EVENING ON FRIDAY...KEEPING 500MB AND 700MB
TEMPERATURES AT ONE TO TWO STANDARDIZED ANOMALIES BELOW NORMAL.
COMBINED WITH A LITTLE MORE LOW-LEVEL HEATING ON FRIDAY...THE
SLIGHT WARM TEMPERATURE NOSE/CAP NEAR 650MB YESTERDAY AND TODAY IS
EXPECTED TO BE OVERCOME BY THIS AND THUS FORECAST SOUNDINGS
PROVIDE 800 TO 1300 J/KG OF MLCAPE OVER SOUTHERN WI/NORTHERN IL
DESPITE FORECAST DEW POINTS ONLY IN THE UPPER 50S. OVERALL
COVERAGE OF STORMS IS EXPECTED TO BE HIGHER IN THE REGION THAN THE
PAST COUPLE DAYS BECAUSE OF THIS...MAYBE SIMILAR TO TUESDAY. A
FEW STRONGER UPDRAFTS AND ASSOCIATED GUSTY DOWNDRAFTS ARE POSSIBLE
IN THE REGION DURING MID- AFTERNOON THROUGH MID-EVE.

THIS WEEKEND...
HIGH PRESSURE...ALBEIT WEAK...IS FORECAST TO BUILD SOUTHEASTWARD
ACROSS THE REGION EARLY IN THE WEEKEND IN ASSOCIATION WITH HEIGHT
RISES ALOFT. A DEVELOPING WEAK COOL FRONT AHEAD OF THE HIGH LOOKS
TO BE A MODEST FOCUS FOR SCATTERED AFTERNOON SHOWERS/STORMS IN THE
LOWER GREAT LAKES REGION. THIS COULD BE PRIMARILY EAST OF THE
LOCAL AREA BASED ON SOME GUIDANCE...BUT GIVEN THE MODEL SPREAD AND
THE SUBTLE FEATURES THAT COULD SPARK SOME SHOWERS...FELT PRUDENT
TO KEEP CHANCE POPS DURING THE DAY. NORTHEAST FLOW IS ANTICIPATED
TO DEVELOP AND DEPENDING ON TIMING COULD PROVIDE A STRONGER LAKE
BREEZE WITH AFTERNOON COOLING IN LAKE ADJACENT COUNTIES. THE HIGH
LOOKS TO MAKE FOR A PLEASANT WEATHER SATURDAY NIGHT THROUGH THE
END OF THE WEEKEND.

MONDAY THROUGH WEDNESDAY...
THE UPPER FLOW WILL BE MORE DAMPENED AND THUS A LITTLE MORE
PROGRESSIVE. LONG RANGE ENSEMBLES AND FORECAST MODELS HAVE MODEST
AGREEMENT ON A JET MAXIMA TRAVERSING THE NORTHERN U.S. SOMETIME
MIDWEEK WITH AN ASSOCIATED WAVE IN THE MID-LEVELS AND A CLOSED
SURFACE LOW DEVELOPING IN THE PLAINS AND MOVING EASTWARD. GIVEN
THE DISTANCE THOUGH SEE LITTLE OPPORTUNITY TO IMPROVE MUCH FROM A
WELL-VERIFYING BLEND OF MODELS PROVIDING CHANCE POPS AREA-WIDE IN
THAT TIME PERIOD. WITH A CLOSED SURFACE LOW OF 1005 OR STRONGER ON
BOTH THE 31.00 GFS AND EC...CANT RULE OUT STRONGER STORMS IN THE
REGION BUT FAR TOO EARLY TO GET ANYWHERE NEAR SPECIFIC.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* ISOL -SHRA WITH A MINIMAL CHANCE OF TSRA.

JEE

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE IS OVER THE REGION WITH MANY SITES INDICATING CALM
WINDS AND THE EARLY STAGES OF FOG DEVELOPMENT. EXPECTING FOG TO BE
THE WORST AT GYY WITH IFR FOG PSBL. DPA WILL ALSO SEE MVFR FOG.
FOG WILL QUICKLY BURN OFF THIS MORNING WITH AMPLE MIXING EXPECTED.
WEST WINDS WILL BE 10-15 KT WITH OCNL GUSTS PSBL. THE STRONG FLOW
WILL KEEP THE LAKE BREEZE ALONG THE SHORELINE. ISOL SHRA ARE
EXPECTED TO FORM ALONG THE LAKE BREEZE AND NORTHERN IL. CONFIDENCE
IS MEDIUM IN LOCATION AND COVERAGE SO BACKED OFF ON PRECIP BY
REPLACING THE VCSH WITH A PROB30. STABILITY WILL LIMIT TSRA
DEVELOPMENT AS WELL. SHOWERS DISSIPATE THIS EVENING AND LIGHT SW
WINDS ARE EXPECTED OVERNIGHT.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM CONFIDENCE IN SHRA COVERAGE AND LOCATION.

* MEDIUM CONFIDENCE IN A VERY VERY LOW CHANCE OF TSRA DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY AND SATURDAY...AFTERNOON ISOLATED SHRA/TSRA. AFTERNOON
  LAKE BREEZES.
* SUNDAY AND MONDAY...DRY/VFR.
* TUESDAY...CHANCE OF TSRA.

&&

.MARINE...
257 AM CDT

BROAD HIGH PRESSURE IS OVER THE REGION WITH A WEAK LOW OVER JAMES
BAY.  SOUTHWEST 10-15KT WINDS WILL BECOME SOUTH THIS AFTERNOON. MAY
SEE PATCHY FOG FORM OVER THE LAKE AGAIN...BUT WITH SHOWERS...A FEW
STORMS...AND DECENT FLOW...DECIDED TO KEEP PATCHY FOG OUT OF THE
GRIDS FOR NOW. IF FOG DOES FORM...IT WOULD BE IN THE AFTERNOON
THROUGH THE EVENING. A WEAK COLD FRONT WILL MOVE DOWN THE NORTH HALF
OF THE LAKE TONIGHT WITH WINDS BECOMING VARIABLE BEHIND IT. THE
SOUTH HALF WILL CONTINUE TO SEE SOUTHWEST WINDS. THE FRONT WILL
DISSIPATE OVER THE LAKE EARLY FRIDAY.

A CONTINUED LIGHT PRESSURE GRADIENT OVER THE LAKE THROUGH MONDAY
WILL MEAN SPEEDS LESS THAN 15 KT AND EVEN BEING VARIABLE AT
TIMES...WITH AFTERNOON LAKE BREEZES IN NEARSHORE AREAS. FRIDAY LOOKS
TO BE A DAY SIMILAR TO THIS PAST TUESDAY...WITH SCATTERED STORMS OF
OVER CENTRAL WI TO NORTHERN IL...SOME OF WHICH COULD BE GUSTY AND
TRAVERSE INTO THE WESTERN NEARSHORE AREAS WHERE STABILITY IS NOT
AS HIGH. SO WHILE GENERALLY TRANQUIL CONDITIONS THE NEXT SEVERAL
DAYS...THAT IS SOMETHING FOR MARINERS IN THE NEARSHORE TO BE AWARE
OF.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO








000
FXUS63 KLOT 310805
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
305 AM CDT THU JUL 31 2014

.DISCUSSION...
257 AM CDT

SYNOPSIS...ROUNDS OF AFTERNOON SHOWERS AND THUNDERSTORMS WILL
CONTINUE THROUGH THE END OF THE WEEK.  MINIMAL CHANCES OF THUNDER
TODAY...BUT HIGHER CHANCES LOOK TO ARRIVE TOMORROW AND SATURDAY.
TEMPERATURES REMAIN AROUND 80 THROUGH THE WEEKEND EXCEPT FOR ALONG
THE LAKE WHERE LAKE BREEZES WILL KEEP HIGHS IN THE 70S TOMORROW
THROUGH THE WEEKEND. A BRIEF WARM UP INTO THE MID 80S IS EXPECTED
EARLY NEXT WEEK.

TODAY AND TONIGHT...
PREPARE FOR A VERY FAMILIAR SONG AND DANCE...BROAD HIGH PRESSURE IS
OVER THE REGION WITH LIGHT FLOW AND PATCHY FOG. THE FOG WILL BURN
OFF QUICKLY THIS MORNING AS MIXING GETS GOING. LOOKING AT A BREEZY
DAY WITH WEST WINDS AT 10-15 KT. A LAKE BREEZE WILL FORM...BUT
EXPECTING IT TO STAY JUST OFF SHORE AS WIND SPEEDS ARE AT 10+ KT
THROUGH THE COLUMN.

AN UPPER LEVEL VORT STREAMER APPROACHES FROM THE NORTHWEST TODAY.
THEREFORE...WEAK FORCING WILL BE OVER NORTHERN IL AND FAR NORTHERN
IN...SO HAVE ANOTHER ROUND OF ISOLATED TO SCATTERED SHOWERS IN THE
FORECAST. BASED ON YESTERDAYS LIMITED ACTIVITY...THINKING WE WILL
SEE FEW IF ANY THUNDERSTORMS. THE DVN SOUNDING FEATURED A CAP
AROUND 650MB YESTERDAY AND MODEL GUIDANCE HAS A SIMILAR CAP IN
STORE FOR US TODAY. THE BEST CHANCE FOR SHOWERS WILL BE NORTH OF
I-80. NOT EXPECTING MUCH PRECIP FROM ANY SHOWERS THAT DO FORM.

HIGH TEMPS WILL BE AROUND 80 AND OVERNIGHT LOWS WILL BE AROUND
60...EXCEPT FOR THE MID 60S DOWNTOWN. MAY SEE FOG AGAIN TOMORROW
NIGHT...BUT NOT OVERLY IMPRESSED SO LEFT FOG OUT OF THE FORECAST FOR
NOW.

JEE

FRIDAY...
THE UPPER PATTERN REMAINS THE SAME FOR ONE MORE DAY INTO FRIDAY WITH
THE FORECAST AREA REMAINING ON THE SOUTHWEST SIDE OF THE EASTERN
CANADIAN LONG WAVE TROUGH. ONE OR TWO SHORT WAVE IMPULSES ARE
PROJECTED TO MOVE AROUND THE TROUGH IN THE NORTHWEST FLOW ALOFT
DURING THE DAY AND EVENING ON FRIDAY...KEEPING 500MB AND 700MB
TEMPERATURES AT ONE TO TWO STANDARDIZED ANOMALIES BELOW NORMAL.
COMBINED WITH A LITTLE MORE LOW-LEVEL HEATING ON FRIDAY...THE
SLIGHT WARM TEMPERATURE NOSE/CAP NEAR 650MB YESTERDAY AND TODAY IS
EXPECTED TO BE OVERCOME BY THIS AND THUS FORECAST SOUNDINGS
PROVIDE 800 TO 1300 J/KG OF MLCAPE OVER SOUTHERN WI/NORTHERN IL
DESPITE FORECAST DEW POINTS ONLY IN THE UPPER 50S. OVERALL
COVERAGE OF STORMS IS EXPECTED TO BE HIGHER IN THE REGION THAN THE
PAST COUPLE DAYS BECAUSE OF THIS...MAYBE SIMILAR TO TUESDAY. A
FEW STRONGER UPDRAFTS AND ASSOCIATED GUSTY DOWNDRAFTS ARE POSSIBLE
IN THE REGION DURING MID- AFTERNOON THROUGH MID-EVE.

THIS WEEKEND...
HIGH PRESSURE...ALBEIT WEAK...IS FORECAST TO BUILD SOUTHEASTWARD
ACROSS THE REGION EARLY IN THE WEEKEND IN ASSOCIATION WITH HEIGHT
RISES ALOFT. A DEVELOPING WEAK COOL FRONT AHEAD OF THE HIGH LOOKS
TO BE A MODEST FOCUS FOR SCATTERED AFTERNOON SHOWERS/STORMS IN THE
LOWER GREAT LAKES REGION. THIS COULD BE PRIMARILY EAST OF THE
LOCAL AREA BASED ON SOME GUIDANCE...BUT GIVEN THE MODEL SPREAD AND
THE SUBTLE FEATURES THAT COULD SPARK SOME SHOWERS...FELT PRUDENT
TO KEEP CHANCE POPS DURING THE DAY. NORTHEAST FLOW IS ANTICIPATED
TO DEVELOP AND DEPENDING ON TIMING COULD PROVIDE A STRONGER LAKE
BREEZE WITH AFTERNOON COOLING IN LAKE ADJACENT COUNTIES. THE HIGH
LOOKS TO MAKE FOR A PLEASANT WEATHER SATURDAY NIGHT THROUGH THE
END OF THE WEEKEND.

MONDAY THROUGH WEDNESDAY...
THE UPPER FLOW WILL BE MORE DAMPENED AND THUS A LITTLE MORE
PROGRESSIVE. LONG RANGE ENSEMBLES AND FORECAST MODELS HAVE MODEST
AGREEMENT ON A JET MAXIMA TRAVERSING THE NORTHERN U.S. SOMETIME
MIDWEEK WITH AN ASSOCIATED WAVE IN THE MID-LEVELS AND A CLOSED
SURFACE LOW DEVELOPING IN THE PLAINS AND MOVING EASTWARD. GIVEN
THE DISTANCE THOUGH SEE LITTLE OPPORTUNITY TO IMPROVE MUCH FROM A
WELL-VERIFYING BLEND OF MODELS PROVIDING CHANCE POPS AREA-WIDE IN
THAT TIME PERIOD. WITH A CLOSED SURFACE LOW OF 1005 OR STRONGER ON
BOTH THE 31.00 GFS AND EC...CANT RULE OUT STRONGER STORMS IN THE
REGION BUT FAR TOO EARLY TO GET ANYWHERE NEAR SPECIFIC.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* ISOL -SHRA WITH A MINIMAL CHANCE OF TSRA.

JEE

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE IS OVER THE REGION WITH MANY SITES INDICATING CALM
WINDS AND THE EARLY STAGES OF FOG DEVELOPMENT. EXPECTING FOG TO BE
THE WORST AT GYY WITH IFR FOG PSBL. DPA WILL ALSO SEE MVFR FOG.
FOG WILL QUICKLY BURN OFF THIS MORNING WITH AMPLE MIXING EXPECTED.
WEST WINDS WILL BE 10-15 KT WITH OCNL GUSTS PSBL. THE STRONG FLOW
WILL KEEP THE LAKE BREEZE ALONG THE SHORELINE. ISOL SHRA ARE
EXPECTED TO FORM ALONG THE LAKE BREEZE AND NORTHERN IL. CONFIDENCE
IS MEDIUM IN LOCATION AND COVERAGE SO BACKED OFF ON PRECIP BY
REPLACING THE VCSH WITH A PROB30. STABILITY WILL LIMIT TSRA
DEVELOPMENT AS WELL. SHOWERS DISSIPATE THIS EVENING AND LIGHT SW
WINDS ARE EXPECTED OVERNIGHT.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM CONFIDENCE IN SHRA COVERAGE AND LOCATION.

* MEDIUM CONFIDENCE IN A VERY VERY LOW CHANCE OF TSRA DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY AND SATURDAY...AFTERNOON ISOLATED SHRA/TSRA. AFTERNOON
  LAKE BREEZES.
* SUNDAY AND MONDAY...DRY/VFR.
* TUESDAY...CHANCE OF TSRA.

&&

.MARINE...
257 AM CDT

BROAD HIGH PRESSURE IS OVER THE REGION WITH A WEAK LOW OVER JAMES
BAY.  SOUTHWEST 10-15KT WINDS WILL BECOME SOUTH THIS AFTERNOON. MAY
SEE PATCHY FOG FORM OVER THE LAKE AGAIN...BUT WITH SHOWERS...A FEW
STORMS...AND DECENT FLOW...DECIDED TO KEEP PATCHY FOG OUT OF THE
GRIDS FOR NOW. IF FOG DOES FORM...IT WOULD BE IN THE AFTERNOON
THROUGH THE EVENING. A WEAK COLD FRONT WILL MOVE DOWN THE NORTH HALF
OF THE LAKE TONIGHT WITH WINDS BECOMING VARIABLE BEHIND IT. THE
SOUTH HALF WILL CONTINUE TO SEE SOUTHWEST WINDS. THE FRONT WILL
DISSIPATE OVER THE LAKE EARLY FRIDAY.

A CONTINUED LIGHT PRESSURE GRADIENT OVER THE LAKE THROUGH MONDAY
WILL MEAN SPEEDS LESS THAN 15 KT AND EVEN BEING VARIABLE AT
TIMES...WITH AFTERNOON LAKE BREEZES IN NEARSHORE AREAS. FRIDAY LOOKS
TO BE A DAY SIMILAR TO THIS PAST TUESDAY...WITH SCATTERED STORMS OF
OVER CENTRAL WI TO NORTHERN IL...SOME OF WHICH COULD BE GUSTY AND
TRAVERSE INTO THE WESTERN NEARSHORE AREAS WHERE STABILITY IS NOT
AS HIGH. SO WHILE GENERALLY TRANQUIL CONDITIONS THE NEXT SEVERAL
DAYS...THAT IS SOMETHING FOR MARINERS IN THE NEARSHORE TO BE AWARE
OF.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO








000
FXUS63 KLOT 310805
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
305 AM CDT THU JUL 31 2014

.DISCUSSION...
257 AM CDT

SYNOPSIS...ROUNDS OF AFTERNOON SHOWERS AND THUNDERSTORMS WILL
CONTINUE THROUGH THE END OF THE WEEK.  MINIMAL CHANCES OF THUNDER
TODAY...BUT HIGHER CHANCES LOOK TO ARRIVE TOMORROW AND SATURDAY.
TEMPERATURES REMAIN AROUND 80 THROUGH THE WEEKEND EXCEPT FOR ALONG
THE LAKE WHERE LAKE BREEZES WILL KEEP HIGHS IN THE 70S TOMORROW
THROUGH THE WEEKEND. A BRIEF WARM UP INTO THE MID 80S IS EXPECTED
EARLY NEXT WEEK.

TODAY AND TONIGHT...
PREPARE FOR A VERY FAMILIAR SONG AND DANCE...BROAD HIGH PRESSURE IS
OVER THE REGION WITH LIGHT FLOW AND PATCHY FOG. THE FOG WILL BURN
OFF QUICKLY THIS MORNING AS MIXING GETS GOING. LOOKING AT A BREEZY
DAY WITH WEST WINDS AT 10-15 KT. A LAKE BREEZE WILL FORM...BUT
EXPECTING IT TO STAY JUST OFF SHORE AS WIND SPEEDS ARE AT 10+ KT
THROUGH THE COLUMN.

AN UPPER LEVEL VORT STREAMER APPROACHES FROM THE NORTHWEST TODAY.
THEREFORE...WEAK FORCING WILL BE OVER NORTHERN IL AND FAR NORTHERN
IN...SO HAVE ANOTHER ROUND OF ISOLATED TO SCATTERED SHOWERS IN THE
FORECAST. BASED ON YESTERDAYS LIMITED ACTIVITY...THINKING WE WILL
SEE FEW IF ANY THUNDERSTORMS. THE DVN SOUNDING FEATURED A CAP
AROUND 650MB YESTERDAY AND MODEL GUIDANCE HAS A SIMILAR CAP IN
STORE FOR US TODAY. THE BEST CHANCE FOR SHOWERS WILL BE NORTH OF
I-80. NOT EXPECTING MUCH PRECIP FROM ANY SHOWERS THAT DO FORM.

HIGH TEMPS WILL BE AROUND 80 AND OVERNIGHT LOWS WILL BE AROUND
60...EXCEPT FOR THE MID 60S DOWNTOWN. MAY SEE FOG AGAIN TOMORROW
NIGHT...BUT NOT OVERLY IMPRESSED SO LEFT FOG OUT OF THE FORECAST FOR
NOW.

JEE

FRIDAY...
THE UPPER PATTERN REMAINS THE SAME FOR ONE MORE DAY INTO FRIDAY WITH
THE FORECAST AREA REMAINING ON THE SOUTHWEST SIDE OF THE EASTERN
CANADIAN LONG WAVE TROUGH. ONE OR TWO SHORT WAVE IMPULSES ARE
PROJECTED TO MOVE AROUND THE TROUGH IN THE NORTHWEST FLOW ALOFT
DURING THE DAY AND EVENING ON FRIDAY...KEEPING 500MB AND 700MB
TEMPERATURES AT ONE TO TWO STANDARDIZED ANOMALIES BELOW NORMAL.
COMBINED WITH A LITTLE MORE LOW-LEVEL HEATING ON FRIDAY...THE
SLIGHT WARM TEMPERATURE NOSE/CAP NEAR 650MB YESTERDAY AND TODAY IS
EXPECTED TO BE OVERCOME BY THIS AND THUS FORECAST SOUNDINGS
PROVIDE 800 TO 1300 J/KG OF MLCAPE OVER SOUTHERN WI/NORTHERN IL
DESPITE FORECAST DEW POINTS ONLY IN THE UPPER 50S. OVERALL
COVERAGE OF STORMS IS EXPECTED TO BE HIGHER IN THE REGION THAN THE
PAST COUPLE DAYS BECAUSE OF THIS...MAYBE SIMILAR TO TUESDAY. A
FEW STRONGER UPDRAFTS AND ASSOCIATED GUSTY DOWNDRAFTS ARE POSSIBLE
IN THE REGION DURING MID- AFTERNOON THROUGH MID-EVE.

THIS WEEKEND...
HIGH PRESSURE...ALBEIT WEAK...IS FORECAST TO BUILD SOUTHEASTWARD
ACROSS THE REGION EARLY IN THE WEEKEND IN ASSOCIATION WITH HEIGHT
RISES ALOFT. A DEVELOPING WEAK COOL FRONT AHEAD OF THE HIGH LOOKS
TO BE A MODEST FOCUS FOR SCATTERED AFTERNOON SHOWERS/STORMS IN THE
LOWER GREAT LAKES REGION. THIS COULD BE PRIMARILY EAST OF THE
LOCAL AREA BASED ON SOME GUIDANCE...BUT GIVEN THE MODEL SPREAD AND
THE SUBTLE FEATURES THAT COULD SPARK SOME SHOWERS...FELT PRUDENT
TO KEEP CHANCE POPS DURING THE DAY. NORTHEAST FLOW IS ANTICIPATED
TO DEVELOP AND DEPENDING ON TIMING COULD PROVIDE A STRONGER LAKE
BREEZE WITH AFTERNOON COOLING IN LAKE ADJACENT COUNTIES. THE HIGH
LOOKS TO MAKE FOR A PLEASANT WEATHER SATURDAY NIGHT THROUGH THE
END OF THE WEEKEND.

MONDAY THROUGH WEDNESDAY...
THE UPPER FLOW WILL BE MORE DAMPENED AND THUS A LITTLE MORE
PROGRESSIVE. LONG RANGE ENSEMBLES AND FORECAST MODELS HAVE MODEST
AGREEMENT ON A JET MAXIMA TRAVERSING THE NORTHERN U.S. SOMETIME
MIDWEEK WITH AN ASSOCIATED WAVE IN THE MID-LEVELS AND A CLOSED
SURFACE LOW DEVELOPING IN THE PLAINS AND MOVING EASTWARD. GIVEN
THE DISTANCE THOUGH SEE LITTLE OPPORTUNITY TO IMPROVE MUCH FROM A
WELL-VERIFYING BLEND OF MODELS PROVIDING CHANCE POPS AREA-WIDE IN
THAT TIME PERIOD. WITH A CLOSED SURFACE LOW OF 1005 OR STRONGER ON
BOTH THE 31.00 GFS AND EC...CANT RULE OUT STRONGER STORMS IN THE
REGION BUT FAR TOO EARLY TO GET ANYWHERE NEAR SPECIFIC.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* ISOL -SHRA WITH A MINIMAL CHANCE OF TSRA.

JEE

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE IS OVER THE REGION WITH MANY SITES INDICATING CALM
WINDS AND THE EARLY STAGES OF FOG DEVELOPMENT. EXPECTING FOG TO BE
THE WORST AT GYY WITH IFR FOG PSBL. DPA WILL ALSO SEE MVFR FOG.
FOG WILL QUICKLY BURN OFF THIS MORNING WITH AMPLE MIXING EXPECTED.
WEST WINDS WILL BE 10-15 KT WITH OCNL GUSTS PSBL. THE STRONG FLOW
WILL KEEP THE LAKE BREEZE ALONG THE SHORELINE. ISOL SHRA ARE
EXPECTED TO FORM ALONG THE LAKE BREEZE AND NORTHERN IL. CONFIDENCE
IS MEDIUM IN LOCATION AND COVERAGE SO BACKED OFF ON PRECIP BY
REPLACING THE VCSH WITH A PROB30. STABILITY WILL LIMIT TSRA
DEVELOPMENT AS WELL. SHOWERS DISSIPATE THIS EVENING AND LIGHT SW
WINDS ARE EXPECTED OVERNIGHT.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM CONFIDENCE IN SHRA COVERAGE AND LOCATION.

* MEDIUM CONFIDENCE IN A VERY VERY LOW CHANCE OF TSRA DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY AND SATURDAY...AFTERNOON ISOLATED SHRA/TSRA. AFTERNOON
  LAKE BREEZES.
* SUNDAY AND MONDAY...DRY/VFR.
* TUESDAY...CHANCE OF TSRA.

&&

.MARINE...
257 AM CDT

BROAD HIGH PRESSURE IS OVER THE REGION WITH A WEAK LOW OVER JAMES
BAY.  SOUTHWEST 10-15KT WINDS WILL BECOME SOUTH THIS AFTERNOON. MAY
SEE PATCHY FOG FORM OVER THE LAKE AGAIN...BUT WITH SHOWERS...A FEW
STORMS...AND DECENT FLOW...DECIDED TO KEEP PATCHY FOG OUT OF THE
GRIDS FOR NOW. IF FOG DOES FORM...IT WOULD BE IN THE AFTERNOON
THROUGH THE EVENING. A WEAK COLD FRONT WILL MOVE DOWN THE NORTH HALF
OF THE LAKE TONIGHT WITH WINDS BECOMING VARIABLE BEHIND IT. THE
SOUTH HALF WILL CONTINUE TO SEE SOUTHWEST WINDS. THE FRONT WILL
DISSIPATE OVER THE LAKE EARLY FRIDAY.

A CONTINUED LIGHT PRESSURE GRADIENT OVER THE LAKE THROUGH MONDAY
WILL MEAN SPEEDS LESS THAN 15 KT AND EVEN BEING VARIABLE AT
TIMES...WITH AFTERNOON LAKE BREEZES IN NEARSHORE AREAS. FRIDAY LOOKS
TO BE A DAY SIMILAR TO THIS PAST TUESDAY...WITH SCATTERED STORMS OF
OVER CENTRAL WI TO NORTHERN IL...SOME OF WHICH COULD BE GUSTY AND
TRAVERSE INTO THE WESTERN NEARSHORE AREAS WHERE STABILITY IS NOT
AS HIGH. SO WHILE GENERALLY TRANQUIL CONDITIONS THE NEXT SEVERAL
DAYS...THAT IS SOMETHING FOR MARINERS IN THE NEARSHORE TO BE AWARE
OF.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO








000
FXUS63 KLOT 310551
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1251 AM CDT THU JUL 31 2014

.DISCUSSION...
844 PM CDT

TEMPERATURES CONTINUE TO HOLD-UP AROUND 70 FOR MOST OF THE AREA.
THE EXCEPTION IS LOCATIONS ADJACENT TO LAKE MICHIGAN WHERE THE
COOLER MARINE ENVIRONMENT HAS BEEN ABLE TO KEEP TEMPS IN THE MID
60S THIS EVENING WITH A CONTINUED ONSHORE FLOW. EXPECT WINDS TO
TURN AROUND FROM THE SOUTH OVERNIGHT. THIS WILL LIKELY KEEP THE
URBAN AREAS A LITTLE WARMER. ELSEWHERE TEMPS SHUD CONTINUE TO
SLOWLY COOL INTO THE MID/UPR 50S.

BEACHLER

//PREV DISCUSSION...
254 PM CDT

A HIGH AMPLITUDE LONGWAVE PATTERN THAT HAS BEEN IN PLACE FOR THE
PAST FEW DAYS WILL PERSIST FOR THE NEXT FEW DAYS WITH DEEP LONG WAVE
TROUGHING OVER THE ERN CONUS AND AN UPPER LOW CENTER OVER JAMES
BAY...WITH RIDGING OVER THE WRN CONUS.  THE LOCAL AREA WILL REMAIN
UNDER GENERALLY NWLY FLOW ALOFT UNDER THE SWRN PERIPHERY OF THE
UPPER LOW.  THIS WILL ALLOW FOR A SERIES OF WEAK SHORT WAVES TO
RIPPLE THROUGH THE NWLY FLOW ALOFT OVER THE LOCAL AREA.

FOR THE REMAINDER OF THIS AFTERNOON AND THIS EVENING...THE MAIN
CONCERN WILL BE THE LAKE BREEZE BOUNDARY QUICKLY PUSHING INLAND
THROUGH NERN IL AND NWRN IN.  TEMPERATURES WILL DROP OFF SEVERAL
DEGREES WITH THE PASSAGE OF THE BOUNDARY AND LAKEFRONT LOCATIONS
HAVE ALREADY DROPPED INTO THE MIDDLE 60S.  THE ENVIRONMENT AHEAD OF
THE BOUNDARY IS MODESTLY MOIST AND UNSTABLE.  WITH CYCLONIC FLOW
ALOFT...DIURNAL CU HAS BEEN DEVELOPING OVER THE REGION PER THE LATEST
SATELLITE IMAGERY.  AS OF EARLY THIS AFTERNOON...HAVE NOT SEEN ANY
SHRA/TSRA ACTIVITY OVER NRN IL/NWRN IN...BUT THE REGION REMAINS
MODESTLY UNSTABLE WITH DEWPOINTS IN THE MIDDLE TO UPPER 50S.  THERE
WILL STILL BE A CHANCE FOR SOME SHRA/TSRA FOCUSED ALONG THE LAKE
BREEZE BOUNDARY AS WELL AS SOME ISOLD SHRA OR AN EVEN MORE ISOLD TS
OVER THE AREA THROUGH SUNSET.  DURG THE EVENING AND INTO THE
OVERNIGHT HOURS...ANY DIURNAL PCPN WILL DISSIPATE AND AND RESIDUAL
PCPN WILL BE WELL NORTH OF THE AREA INVOF ON OF THE SEEMINGLY
ENDLESS SERIES OF IMPULSES DROPPING THROUGH THE NORTHWEST FLOW.

LITTLE CHANGE IS EXPECTED FOR TOMORROW THROUGH SATURDAY AS THE
SYNOPTIC SCALE PATTERN SHOULD CHANGE LITTLE AND A WEAK GRADIENT
PATTERN WILL PERSIST AT THE SFC.  UNDER PERSISTENT NWLY FLOW
ALOFT...THE SERIES OF WEAK SHORTWAVES WILL CONTINUE TO BRING
PERIODIC CHANCES FOR SCT SHRA AND ISOLD TSRA...WITH THE BETTER
CHANCES FOR TS DURG THE AFTERNOON HOURS.  THE WEAK GRADIENT PATTERN
AT THE SFC SHOULD ALLOW FOR DAILY LAKE BREEZE DEVELOPMENT...WITH THE
MAIN QUESTION BEING HOW FAR INLAND A LAKE BREEZE WILL PENETRATE.
CERTAINLY...IT IS LIKELY THAT LAKEFRONT LOCATIONS WILL TURN COOLER
IN THE AFTERNOON...BUT IT IS LESS CERTAIN HOW FAR INLAND THE LAKE
COOLING WILL PENETRATE.  SO...WILL KEEP THE MAX TEMP FORECAST A BIT
ON THE CONSERVATIVE SIDE AS FAR AS LAKE INFLUENCE IS CONCERNED AND
LIMIT THE COOLING TO THE IMMEDIATE LAKEFRONT AND ALLOW MAX TEMPS TO
BE MORE REPRESENTATIVE OF THE LARGE SCALE PATTERN.  UNDER THE COOL
NWLY FLOW ALOFT...HIGHS WILL REMAIN A FEW DEGREES BELOW NORMAL INTO
THE WEEKEND WITH HIGHS AROUND 80F OR SO.  TIMING OF PERIODS OF PCPN
WILL BE LESS CERTAIN THAN THE TEMPERATURE TRENDS FOR THE NEXT FEW
DAYS AND WILL GENERALLY BE DEPENDENT ON THE TIMING OF SHORTWAVE
ENERGY DROPPING THROUGH THE NWLY FLOW ALOFT.  SO...WHILE NO DAY IN
THE SHORT TERM FORECAST PERIOD WILL BE A TOTAL WASHOUT...THERE
SHOULD BE PERIODS OF SCT SHRA AND ISOLD TSRA.

THE LONGER RANGE GUIDANCE IS IN GENERALLY GOOD AGREEMENT ON THE
UPPER LEVEL PATTERN BECOMING MORE PROGRESSIVE THROUGH THE WEEKEND.
THIS WILL INITIATE A WARMING TREND AS THE UPPER LEVEL RIDGING MOVES
OUT OVER THE WESTERN PLAINS ON SUNDAY WHILE THE UPPER LOW OVER JAMES
BAY KICKS OUT TO THE NORTHEAST...LEAVING WEAKER LONGWAVE TROUGHING
OVER THE ERN CONUS.  SUNDAY SHOULD BE A TRANSITIONAL DAY...WITH
INLAND TEMPS A LITTLE HIGHER...BUT A WEAK GRADIENT PERSISTING AT THE
SURFACE WILL ALLOW FOR ANOTHER LAKE BREEZE DAY AND COOLER CONDITIONS
NEAR THE LAKE. RISING HEIGHTS OVER THE MIDWEST SHOULD ALLOW FOR MAX
TEMPS TO CLIMB INTO THE MIDDLE 80S BY MONDAY.

MORE UNCERTAINTY WILL CREEP INTO THE FORECAST DURING THE EXTENDED
FORECAST PERIOD AS FLOW BECOMES MORE ZONAL OVER THE MIDWEST.  IN THE
INCREASINGLY ZONAL FLOW...SHORT WAVE STRENGTH AND TIMING WILL BECOME
MORE UNCERTAIN...SO...CONFIDENCE IN THE SENSIBLE WEATHER FORECAST
WILL INCREASE WITH TIME THROUGH THE EXTENDED FORECAST PERIOD.
HOWEVER...THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THE WARMING
TREND COULD BE BRIEF AS A WEAK UPPER LOW HANGS BACK OVER THE LOWER
MISSISSIPPI VALLEY THROUGH THE PERIOD AND THE UPPER RIDGING WILL NOT
BUILD ANY FARTHER EAST THAN THE CENTRAL PLAINS.  ALSO...THE SFC
PATTERN SHOULD REMAIN WEAK...SO DAILY LAKE BREEZE DEVELOPMENT WILL
BE LIKELY AS WELL. THE TREND FOR THE EXTENDED FORECAST PERIOD IS
SHAPING UP FOR MORE BELOW NORMAL TEMPERATURES WITH PERIODIC CHANCES
FOR AT LEAST SOME LIGHT PCPN.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* ISOL -SHRA WITH A MINIMAL CHANCE OF TSRA.

JEE

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE IS OVER THE REGION WITH MANY SITES INDICATING CALM
WINDS AND THE EARLY STAGES OF FOG DEVELOPMENT. EXPECTING FOG TO BE
THE WORST AT GYY WITH IFR FOG PSBL. DPA WILL ALSO SEE MVFR FOG.
FOG WILL QUICKLY BURN OFF THIS MORNING WITH AMPLE MIXING EXPECTED.
WEST WINDS WILL BE 10-15 KT WITH OCNL GUSTS PSBL. THE STRONG FLOW
WILL KEEP THE LAKE BREEZE ALONG THE SHORELINE. ISOL SHRA ARE
EXPECTED TO FORM ALONG THE LAKE BREEZE AND NORTHERN IL. CONFIDENCE
IS MEDIUM IN LOCATION AND COVERAGE SO BACKED OFF ON PRECIP BY
REPLACING THE VCSH WITH A PROB30. STABILITY WILL LIMIT TSRA
DEVELOPMENT AS WELL. SHOWERS DISSIPATE THIS EVENING AND LIGHT SW
WINDS ARE EXPECTED OVERNIGHT.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM CONFIDENCE IN SHRA COVERAGE AND LOCATION.

* MEDIUM CONFIDENCE IN A VERY VERY LOW CHANCE OF TSRA DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY AND SATURDAY...AFTERNOON ISOLATED SHRA/TSRA. AFTERNOON
  LAKE BREEZES.
* SUNDAY AND MONDAY...DRY/VFR.
* TUESDAY...CHANCE OF TSRA.

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 310551
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1251 AM CDT THU JUL 31 2014

.DISCUSSION...
844 PM CDT

TEMPERATURES CONTINUE TO HOLD-UP AROUND 70 FOR MOST OF THE AREA.
THE EXCEPTION IS LOCATIONS ADJACENT TO LAKE MICHIGAN WHERE THE
COOLER MARINE ENVIRONMENT HAS BEEN ABLE TO KEEP TEMPS IN THE MID
60S THIS EVENING WITH A CONTINUED ONSHORE FLOW. EXPECT WINDS TO
TURN AROUND FROM THE SOUTH OVERNIGHT. THIS WILL LIKELY KEEP THE
URBAN AREAS A LITTLE WARMER. ELSEWHERE TEMPS SHUD CONTINUE TO
SLOWLY COOL INTO THE MID/UPR 50S.

BEACHLER

//PREV DISCUSSION...
254 PM CDT

A HIGH AMPLITUDE LONGWAVE PATTERN THAT HAS BEEN IN PLACE FOR THE
PAST FEW DAYS WILL PERSIST FOR THE NEXT FEW DAYS WITH DEEP LONG WAVE
TROUGHING OVER THE ERN CONUS AND AN UPPER LOW CENTER OVER JAMES
BAY...WITH RIDGING OVER THE WRN CONUS.  THE LOCAL AREA WILL REMAIN
UNDER GENERALLY NWLY FLOW ALOFT UNDER THE SWRN PERIPHERY OF THE
UPPER LOW.  THIS WILL ALLOW FOR A SERIES OF WEAK SHORT WAVES TO
RIPPLE THROUGH THE NWLY FLOW ALOFT OVER THE LOCAL AREA.

FOR THE REMAINDER OF THIS AFTERNOON AND THIS EVENING...THE MAIN
CONCERN WILL BE THE LAKE BREEZE BOUNDARY QUICKLY PUSHING INLAND
THROUGH NERN IL AND NWRN IN.  TEMPERATURES WILL DROP OFF SEVERAL
DEGREES WITH THE PASSAGE OF THE BOUNDARY AND LAKEFRONT LOCATIONS
HAVE ALREADY DROPPED INTO THE MIDDLE 60S.  THE ENVIRONMENT AHEAD OF
THE BOUNDARY IS MODESTLY MOIST AND UNSTABLE.  WITH CYCLONIC FLOW
ALOFT...DIURNAL CU HAS BEEN DEVELOPING OVER THE REGION PER THE LATEST
SATELLITE IMAGERY.  AS OF EARLY THIS AFTERNOON...HAVE NOT SEEN ANY
SHRA/TSRA ACTIVITY OVER NRN IL/NWRN IN...BUT THE REGION REMAINS
MODESTLY UNSTABLE WITH DEWPOINTS IN THE MIDDLE TO UPPER 50S.  THERE
WILL STILL BE A CHANCE FOR SOME SHRA/TSRA FOCUSED ALONG THE LAKE
BREEZE BOUNDARY AS WELL AS SOME ISOLD SHRA OR AN EVEN MORE ISOLD TS
OVER THE AREA THROUGH SUNSET.  DURG THE EVENING AND INTO THE
OVERNIGHT HOURS...ANY DIURNAL PCPN WILL DISSIPATE AND AND RESIDUAL
PCPN WILL BE WELL NORTH OF THE AREA INVOF ON OF THE SEEMINGLY
ENDLESS SERIES OF IMPULSES DROPPING THROUGH THE NORTHWEST FLOW.

LITTLE CHANGE IS EXPECTED FOR TOMORROW THROUGH SATURDAY AS THE
SYNOPTIC SCALE PATTERN SHOULD CHANGE LITTLE AND A WEAK GRADIENT
PATTERN WILL PERSIST AT THE SFC.  UNDER PERSISTENT NWLY FLOW
ALOFT...THE SERIES OF WEAK SHORTWAVES WILL CONTINUE TO BRING
PERIODIC CHANCES FOR SCT SHRA AND ISOLD TSRA...WITH THE BETTER
CHANCES FOR TS DURG THE AFTERNOON HOURS.  THE WEAK GRADIENT PATTERN
AT THE SFC SHOULD ALLOW FOR DAILY LAKE BREEZE DEVELOPMENT...WITH THE
MAIN QUESTION BEING HOW FAR INLAND A LAKE BREEZE WILL PENETRATE.
CERTAINLY...IT IS LIKELY THAT LAKEFRONT LOCATIONS WILL TURN COOLER
IN THE AFTERNOON...BUT IT IS LESS CERTAIN HOW FAR INLAND THE LAKE
COOLING WILL PENETRATE.  SO...WILL KEEP THE MAX TEMP FORECAST A BIT
ON THE CONSERVATIVE SIDE AS FAR AS LAKE INFLUENCE IS CONCERNED AND
LIMIT THE COOLING TO THE IMMEDIATE LAKEFRONT AND ALLOW MAX TEMPS TO
BE MORE REPRESENTATIVE OF THE LARGE SCALE PATTERN.  UNDER THE COOL
NWLY FLOW ALOFT...HIGHS WILL REMAIN A FEW DEGREES BELOW NORMAL INTO
THE WEEKEND WITH HIGHS AROUND 80F OR SO.  TIMING OF PERIODS OF PCPN
WILL BE LESS CERTAIN THAN THE TEMPERATURE TRENDS FOR THE NEXT FEW
DAYS AND WILL GENERALLY BE DEPENDENT ON THE TIMING OF SHORTWAVE
ENERGY DROPPING THROUGH THE NWLY FLOW ALOFT.  SO...WHILE NO DAY IN
THE SHORT TERM FORECAST PERIOD WILL BE A TOTAL WASHOUT...THERE
SHOULD BE PERIODS OF SCT SHRA AND ISOLD TSRA.

THE LONGER RANGE GUIDANCE IS IN GENERALLY GOOD AGREEMENT ON THE
UPPER LEVEL PATTERN BECOMING MORE PROGRESSIVE THROUGH THE WEEKEND.
THIS WILL INITIATE A WARMING TREND AS THE UPPER LEVEL RIDGING MOVES
OUT OVER THE WESTERN PLAINS ON SUNDAY WHILE THE UPPER LOW OVER JAMES
BAY KICKS OUT TO THE NORTHEAST...LEAVING WEAKER LONGWAVE TROUGHING
OVER THE ERN CONUS.  SUNDAY SHOULD BE A TRANSITIONAL DAY...WITH
INLAND TEMPS A LITTLE HIGHER...BUT A WEAK GRADIENT PERSISTING AT THE
SURFACE WILL ALLOW FOR ANOTHER LAKE BREEZE DAY AND COOLER CONDITIONS
NEAR THE LAKE. RISING HEIGHTS OVER THE MIDWEST SHOULD ALLOW FOR MAX
TEMPS TO CLIMB INTO THE MIDDLE 80S BY MONDAY.

MORE UNCERTAINTY WILL CREEP INTO THE FORECAST DURING THE EXTENDED
FORECAST PERIOD AS FLOW BECOMES MORE ZONAL OVER THE MIDWEST.  IN THE
INCREASINGLY ZONAL FLOW...SHORT WAVE STRENGTH AND TIMING WILL BECOME
MORE UNCERTAIN...SO...CONFIDENCE IN THE SENSIBLE WEATHER FORECAST
WILL INCREASE WITH TIME THROUGH THE EXTENDED FORECAST PERIOD.
HOWEVER...THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THE WARMING
TREND COULD BE BRIEF AS A WEAK UPPER LOW HANGS BACK OVER THE LOWER
MISSISSIPPI VALLEY THROUGH THE PERIOD AND THE UPPER RIDGING WILL NOT
BUILD ANY FARTHER EAST THAN THE CENTRAL PLAINS.  ALSO...THE SFC
PATTERN SHOULD REMAIN WEAK...SO DAILY LAKE BREEZE DEVELOPMENT WILL
BE LIKELY AS WELL. THE TREND FOR THE EXTENDED FORECAST PERIOD IS
SHAPING UP FOR MORE BELOW NORMAL TEMPERATURES WITH PERIODIC CHANCES
FOR AT LEAST SOME LIGHT PCPN.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* ISOL -SHRA WITH A MINIMAL CHANCE OF TSRA.

JEE

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE IS OVER THE REGION WITH MANY SITES INDICATING CALM
WINDS AND THE EARLY STAGES OF FOG DEVELOPMENT. EXPECTING FOG TO BE
THE WORST AT GYY WITH IFR FOG PSBL. DPA WILL ALSO SEE MVFR FOG.
FOG WILL QUICKLY BURN OFF THIS MORNING WITH AMPLE MIXING EXPECTED.
WEST WINDS WILL BE 10-15 KT WITH OCNL GUSTS PSBL. THE STRONG FLOW
WILL KEEP THE LAKE BREEZE ALONG THE SHORELINE. ISOL SHRA ARE
EXPECTED TO FORM ALONG THE LAKE BREEZE AND NORTHERN IL. CONFIDENCE
IS MEDIUM IN LOCATION AND COVERAGE SO BACKED OFF ON PRECIP BY
REPLACING THE VCSH WITH A PROB30. STABILITY WILL LIMIT TSRA
DEVELOPMENT AS WELL. SHOWERS DISSIPATE THIS EVENING AND LIGHT SW
WINDS ARE EXPECTED OVERNIGHT.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM CONFIDENCE IN SHRA COVERAGE AND LOCATION.

* MEDIUM CONFIDENCE IN A VERY VERY LOW CHANCE OF TSRA DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY AND SATURDAY...AFTERNOON ISOLATED SHRA/TSRA. AFTERNOON
  LAKE BREEZES.
* SUNDAY AND MONDAY...DRY/VFR.
* TUESDAY...CHANCE OF TSRA.

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 310551
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1251 AM CDT THU JUL 31 2014

.DISCUSSION...
844 PM CDT

TEMPERATURES CONTINUE TO HOLD-UP AROUND 70 FOR MOST OF THE AREA.
THE EXCEPTION IS LOCATIONS ADJACENT TO LAKE MICHIGAN WHERE THE
COOLER MARINE ENVIRONMENT HAS BEEN ABLE TO KEEP TEMPS IN THE MID
60S THIS EVENING WITH A CONTINUED ONSHORE FLOW. EXPECT WINDS TO
TURN AROUND FROM THE SOUTH OVERNIGHT. THIS WILL LIKELY KEEP THE
URBAN AREAS A LITTLE WARMER. ELSEWHERE TEMPS SHUD CONTINUE TO
SLOWLY COOL INTO THE MID/UPR 50S.

BEACHLER

//PREV DISCUSSION...
254 PM CDT

A HIGH AMPLITUDE LONGWAVE PATTERN THAT HAS BEEN IN PLACE FOR THE
PAST FEW DAYS WILL PERSIST FOR THE NEXT FEW DAYS WITH DEEP LONG WAVE
TROUGHING OVER THE ERN CONUS AND AN UPPER LOW CENTER OVER JAMES
BAY...WITH RIDGING OVER THE WRN CONUS.  THE LOCAL AREA WILL REMAIN
UNDER GENERALLY NWLY FLOW ALOFT UNDER THE SWRN PERIPHERY OF THE
UPPER LOW.  THIS WILL ALLOW FOR A SERIES OF WEAK SHORT WAVES TO
RIPPLE THROUGH THE NWLY FLOW ALOFT OVER THE LOCAL AREA.

FOR THE REMAINDER OF THIS AFTERNOON AND THIS EVENING...THE MAIN
CONCERN WILL BE THE LAKE BREEZE BOUNDARY QUICKLY PUSHING INLAND
THROUGH NERN IL AND NWRN IN.  TEMPERATURES WILL DROP OFF SEVERAL
DEGREES WITH THE PASSAGE OF THE BOUNDARY AND LAKEFRONT LOCATIONS
HAVE ALREADY DROPPED INTO THE MIDDLE 60S.  THE ENVIRONMENT AHEAD OF
THE BOUNDARY IS MODESTLY MOIST AND UNSTABLE.  WITH CYCLONIC FLOW
ALOFT...DIURNAL CU HAS BEEN DEVELOPING OVER THE REGION PER THE LATEST
SATELLITE IMAGERY.  AS OF EARLY THIS AFTERNOON...HAVE NOT SEEN ANY
SHRA/TSRA ACTIVITY OVER NRN IL/NWRN IN...BUT THE REGION REMAINS
MODESTLY UNSTABLE WITH DEWPOINTS IN THE MIDDLE TO UPPER 50S.  THERE
WILL STILL BE A CHANCE FOR SOME SHRA/TSRA FOCUSED ALONG THE LAKE
BREEZE BOUNDARY AS WELL AS SOME ISOLD SHRA OR AN EVEN MORE ISOLD TS
OVER THE AREA THROUGH SUNSET.  DURG THE EVENING AND INTO THE
OVERNIGHT HOURS...ANY DIURNAL PCPN WILL DISSIPATE AND AND RESIDUAL
PCPN WILL BE WELL NORTH OF THE AREA INVOF ON OF THE SEEMINGLY
ENDLESS SERIES OF IMPULSES DROPPING THROUGH THE NORTHWEST FLOW.

LITTLE CHANGE IS EXPECTED FOR TOMORROW THROUGH SATURDAY AS THE
SYNOPTIC SCALE PATTERN SHOULD CHANGE LITTLE AND A WEAK GRADIENT
PATTERN WILL PERSIST AT THE SFC.  UNDER PERSISTENT NWLY FLOW
ALOFT...THE SERIES OF WEAK SHORTWAVES WILL CONTINUE TO BRING
PERIODIC CHANCES FOR SCT SHRA AND ISOLD TSRA...WITH THE BETTER
CHANCES FOR TS DURG THE AFTERNOON HOURS.  THE WEAK GRADIENT PATTERN
AT THE SFC SHOULD ALLOW FOR DAILY LAKE BREEZE DEVELOPMENT...WITH THE
MAIN QUESTION BEING HOW FAR INLAND A LAKE BREEZE WILL PENETRATE.
CERTAINLY...IT IS LIKELY THAT LAKEFRONT LOCATIONS WILL TURN COOLER
IN THE AFTERNOON...BUT IT IS LESS CERTAIN HOW FAR INLAND THE LAKE
COOLING WILL PENETRATE.  SO...WILL KEEP THE MAX TEMP FORECAST A BIT
ON THE CONSERVATIVE SIDE AS FAR AS LAKE INFLUENCE IS CONCERNED AND
LIMIT THE COOLING TO THE IMMEDIATE LAKEFRONT AND ALLOW MAX TEMPS TO
BE MORE REPRESENTATIVE OF THE LARGE SCALE PATTERN.  UNDER THE COOL
NWLY FLOW ALOFT...HIGHS WILL REMAIN A FEW DEGREES BELOW NORMAL INTO
THE WEEKEND WITH HIGHS AROUND 80F OR SO.  TIMING OF PERIODS OF PCPN
WILL BE LESS CERTAIN THAN THE TEMPERATURE TRENDS FOR THE NEXT FEW
DAYS AND WILL GENERALLY BE DEPENDENT ON THE TIMING OF SHORTWAVE
ENERGY DROPPING THROUGH THE NWLY FLOW ALOFT.  SO...WHILE NO DAY IN
THE SHORT TERM FORECAST PERIOD WILL BE A TOTAL WASHOUT...THERE
SHOULD BE PERIODS OF SCT SHRA AND ISOLD TSRA.

THE LONGER RANGE GUIDANCE IS IN GENERALLY GOOD AGREEMENT ON THE
UPPER LEVEL PATTERN BECOMING MORE PROGRESSIVE THROUGH THE WEEKEND.
THIS WILL INITIATE A WARMING TREND AS THE UPPER LEVEL RIDGING MOVES
OUT OVER THE WESTERN PLAINS ON SUNDAY WHILE THE UPPER LOW OVER JAMES
BAY KICKS OUT TO THE NORTHEAST...LEAVING WEAKER LONGWAVE TROUGHING
OVER THE ERN CONUS.  SUNDAY SHOULD BE A TRANSITIONAL DAY...WITH
INLAND TEMPS A LITTLE HIGHER...BUT A WEAK GRADIENT PERSISTING AT THE
SURFACE WILL ALLOW FOR ANOTHER LAKE BREEZE DAY AND COOLER CONDITIONS
NEAR THE LAKE. RISING HEIGHTS OVER THE MIDWEST SHOULD ALLOW FOR MAX
TEMPS TO CLIMB INTO THE MIDDLE 80S BY MONDAY.

MORE UNCERTAINTY WILL CREEP INTO THE FORECAST DURING THE EXTENDED
FORECAST PERIOD AS FLOW BECOMES MORE ZONAL OVER THE MIDWEST.  IN THE
INCREASINGLY ZONAL FLOW...SHORT WAVE STRENGTH AND TIMING WILL BECOME
MORE UNCERTAIN...SO...CONFIDENCE IN THE SENSIBLE WEATHER FORECAST
WILL INCREASE WITH TIME THROUGH THE EXTENDED FORECAST PERIOD.
HOWEVER...THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THE WARMING
TREND COULD BE BRIEF AS A WEAK UPPER LOW HANGS BACK OVER THE LOWER
MISSISSIPPI VALLEY THROUGH THE PERIOD AND THE UPPER RIDGING WILL NOT
BUILD ANY FARTHER EAST THAN THE CENTRAL PLAINS.  ALSO...THE SFC
PATTERN SHOULD REMAIN WEAK...SO DAILY LAKE BREEZE DEVELOPMENT WILL
BE LIKELY AS WELL. THE TREND FOR THE EXTENDED FORECAST PERIOD IS
SHAPING UP FOR MORE BELOW NORMAL TEMPERATURES WITH PERIODIC CHANCES
FOR AT LEAST SOME LIGHT PCPN.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* ISOL -SHRA WITH A MINIMAL CHANCE OF TSRA.

JEE

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE IS OVER THE REGION WITH MANY SITES INDICATING CALM
WINDS AND THE EARLY STAGES OF FOG DEVELOPMENT. EXPECTING FOG TO BE
THE WORST AT GYY WITH IFR FOG PSBL. DPA WILL ALSO SEE MVFR FOG.
FOG WILL QUICKLY BURN OFF THIS MORNING WITH AMPLE MIXING EXPECTED.
WEST WINDS WILL BE 10-15 KT WITH OCNL GUSTS PSBL. THE STRONG FLOW
WILL KEEP THE LAKE BREEZE ALONG THE SHORELINE. ISOL SHRA ARE
EXPECTED TO FORM ALONG THE LAKE BREEZE AND NORTHERN IL. CONFIDENCE
IS MEDIUM IN LOCATION AND COVERAGE SO BACKED OFF ON PRECIP BY
REPLACING THE VCSH WITH A PROB30. STABILITY WILL LIMIT TSRA
DEVELOPMENT AS WELL. SHOWERS DISSIPATE THIS EVENING AND LIGHT SW
WINDS ARE EXPECTED OVERNIGHT.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM CONFIDENCE IN SHRA COVERAGE AND LOCATION.

* MEDIUM CONFIDENCE IN A VERY VERY LOW CHANCE OF TSRA DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY AND SATURDAY...AFTERNOON ISOLATED SHRA/TSRA. AFTERNOON
  LAKE BREEZES.
* SUNDAY AND MONDAY...DRY/VFR.
* TUESDAY...CHANCE OF TSRA.

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 310551
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1251 AM CDT THU JUL 31 2014

.DISCUSSION...
844 PM CDT

TEMPERATURES CONTINUE TO HOLD-UP AROUND 70 FOR MOST OF THE AREA.
THE EXCEPTION IS LOCATIONS ADJACENT TO LAKE MICHIGAN WHERE THE
COOLER MARINE ENVIRONMENT HAS BEEN ABLE TO KEEP TEMPS IN THE MID
60S THIS EVENING WITH A CONTINUED ONSHORE FLOW. EXPECT WINDS TO
TURN AROUND FROM THE SOUTH OVERNIGHT. THIS WILL LIKELY KEEP THE
URBAN AREAS A LITTLE WARMER. ELSEWHERE TEMPS SHUD CONTINUE TO
SLOWLY COOL INTO THE MID/UPR 50S.

BEACHLER

//PREV DISCUSSION...
254 PM CDT

A HIGH AMPLITUDE LONGWAVE PATTERN THAT HAS BEEN IN PLACE FOR THE
PAST FEW DAYS WILL PERSIST FOR THE NEXT FEW DAYS WITH DEEP LONG WAVE
TROUGHING OVER THE ERN CONUS AND AN UPPER LOW CENTER OVER JAMES
BAY...WITH RIDGING OVER THE WRN CONUS.  THE LOCAL AREA WILL REMAIN
UNDER GENERALLY NWLY FLOW ALOFT UNDER THE SWRN PERIPHERY OF THE
UPPER LOW.  THIS WILL ALLOW FOR A SERIES OF WEAK SHORT WAVES TO
RIPPLE THROUGH THE NWLY FLOW ALOFT OVER THE LOCAL AREA.

FOR THE REMAINDER OF THIS AFTERNOON AND THIS EVENING...THE MAIN
CONCERN WILL BE THE LAKE BREEZE BOUNDARY QUICKLY PUSHING INLAND
THROUGH NERN IL AND NWRN IN.  TEMPERATURES WILL DROP OFF SEVERAL
DEGREES WITH THE PASSAGE OF THE BOUNDARY AND LAKEFRONT LOCATIONS
HAVE ALREADY DROPPED INTO THE MIDDLE 60S.  THE ENVIRONMENT AHEAD OF
THE BOUNDARY IS MODESTLY MOIST AND UNSTABLE.  WITH CYCLONIC FLOW
ALOFT...DIURNAL CU HAS BEEN DEVELOPING OVER THE REGION PER THE LATEST
SATELLITE IMAGERY.  AS OF EARLY THIS AFTERNOON...HAVE NOT SEEN ANY
SHRA/TSRA ACTIVITY OVER NRN IL/NWRN IN...BUT THE REGION REMAINS
MODESTLY UNSTABLE WITH DEWPOINTS IN THE MIDDLE TO UPPER 50S.  THERE
WILL STILL BE A CHANCE FOR SOME SHRA/TSRA FOCUSED ALONG THE LAKE
BREEZE BOUNDARY AS WELL AS SOME ISOLD SHRA OR AN EVEN MORE ISOLD TS
OVER THE AREA THROUGH SUNSET.  DURG THE EVENING AND INTO THE
OVERNIGHT HOURS...ANY DIURNAL PCPN WILL DISSIPATE AND AND RESIDUAL
PCPN WILL BE WELL NORTH OF THE AREA INVOF ON OF THE SEEMINGLY
ENDLESS SERIES OF IMPULSES DROPPING THROUGH THE NORTHWEST FLOW.

LITTLE CHANGE IS EXPECTED FOR TOMORROW THROUGH SATURDAY AS THE
SYNOPTIC SCALE PATTERN SHOULD CHANGE LITTLE AND A WEAK GRADIENT
PATTERN WILL PERSIST AT THE SFC.  UNDER PERSISTENT NWLY FLOW
ALOFT...THE SERIES OF WEAK SHORTWAVES WILL CONTINUE TO BRING
PERIODIC CHANCES FOR SCT SHRA AND ISOLD TSRA...WITH THE BETTER
CHANCES FOR TS DURG THE AFTERNOON HOURS.  THE WEAK GRADIENT PATTERN
AT THE SFC SHOULD ALLOW FOR DAILY LAKE BREEZE DEVELOPMENT...WITH THE
MAIN QUESTION BEING HOW FAR INLAND A LAKE BREEZE WILL PENETRATE.
CERTAINLY...IT IS LIKELY THAT LAKEFRONT LOCATIONS WILL TURN COOLER
IN THE AFTERNOON...BUT IT IS LESS CERTAIN HOW FAR INLAND THE LAKE
COOLING WILL PENETRATE.  SO...WILL KEEP THE MAX TEMP FORECAST A BIT
ON THE CONSERVATIVE SIDE AS FAR AS LAKE INFLUENCE IS CONCERNED AND
LIMIT THE COOLING TO THE IMMEDIATE LAKEFRONT AND ALLOW MAX TEMPS TO
BE MORE REPRESENTATIVE OF THE LARGE SCALE PATTERN.  UNDER THE COOL
NWLY FLOW ALOFT...HIGHS WILL REMAIN A FEW DEGREES BELOW NORMAL INTO
THE WEEKEND WITH HIGHS AROUND 80F OR SO.  TIMING OF PERIODS OF PCPN
WILL BE LESS CERTAIN THAN THE TEMPERATURE TRENDS FOR THE NEXT FEW
DAYS AND WILL GENERALLY BE DEPENDENT ON THE TIMING OF SHORTWAVE
ENERGY DROPPING THROUGH THE NWLY FLOW ALOFT.  SO...WHILE NO DAY IN
THE SHORT TERM FORECAST PERIOD WILL BE A TOTAL WASHOUT...THERE
SHOULD BE PERIODS OF SCT SHRA AND ISOLD TSRA.

THE LONGER RANGE GUIDANCE IS IN GENERALLY GOOD AGREEMENT ON THE
UPPER LEVEL PATTERN BECOMING MORE PROGRESSIVE THROUGH THE WEEKEND.
THIS WILL INITIATE A WARMING TREND AS THE UPPER LEVEL RIDGING MOVES
OUT OVER THE WESTERN PLAINS ON SUNDAY WHILE THE UPPER LOW OVER JAMES
BAY KICKS OUT TO THE NORTHEAST...LEAVING WEAKER LONGWAVE TROUGHING
OVER THE ERN CONUS.  SUNDAY SHOULD BE A TRANSITIONAL DAY...WITH
INLAND TEMPS A LITTLE HIGHER...BUT A WEAK GRADIENT PERSISTING AT THE
SURFACE WILL ALLOW FOR ANOTHER LAKE BREEZE DAY AND COOLER CONDITIONS
NEAR THE LAKE. RISING HEIGHTS OVER THE MIDWEST SHOULD ALLOW FOR MAX
TEMPS TO CLIMB INTO THE MIDDLE 80S BY MONDAY.

MORE UNCERTAINTY WILL CREEP INTO THE FORECAST DURING THE EXTENDED
FORECAST PERIOD AS FLOW BECOMES MORE ZONAL OVER THE MIDWEST.  IN THE
INCREASINGLY ZONAL FLOW...SHORT WAVE STRENGTH AND TIMING WILL BECOME
MORE UNCERTAIN...SO...CONFIDENCE IN THE SENSIBLE WEATHER FORECAST
WILL INCREASE WITH TIME THROUGH THE EXTENDED FORECAST PERIOD.
HOWEVER...THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THE WARMING
TREND COULD BE BRIEF AS A WEAK UPPER LOW HANGS BACK OVER THE LOWER
MISSISSIPPI VALLEY THROUGH THE PERIOD AND THE UPPER RIDGING WILL NOT
BUILD ANY FARTHER EAST THAN THE CENTRAL PLAINS.  ALSO...THE SFC
PATTERN SHOULD REMAIN WEAK...SO DAILY LAKE BREEZE DEVELOPMENT WILL
BE LIKELY AS WELL. THE TREND FOR THE EXTENDED FORECAST PERIOD IS
SHAPING UP FOR MORE BELOW NORMAL TEMPERATURES WITH PERIODIC CHANCES
FOR AT LEAST SOME LIGHT PCPN.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* ISOL -SHRA WITH A MINIMAL CHANCE OF TSRA.

JEE

//DISCUSSION...UPDATED 06Z...

HIGH PRESSURE IS OVER THE REGION WITH MANY SITES INDICATING CALM
WINDS AND THE EARLY STAGES OF FOG DEVELOPMENT. EXPECTING FOG TO BE
THE WORST AT GYY WITH IFR FOG PSBL. DPA WILL ALSO SEE MVFR FOG.
FOG WILL QUICKLY BURN OFF THIS MORNING WITH AMPLE MIXING EXPECTED.
WEST WINDS WILL BE 10-15 KT WITH OCNL GUSTS PSBL. THE STRONG FLOW
WILL KEEP THE LAKE BREEZE ALONG THE SHORELINE. ISOL SHRA ARE
EXPECTED TO FORM ALONG THE LAKE BREEZE AND NORTHERN IL. CONFIDENCE
IS MEDIUM IN LOCATION AND COVERAGE SO BACKED OFF ON PRECIP BY
REPLACING THE VCSH WITH A PROB30. STABILITY WILL LIMIT TSRA
DEVELOPMENT AS WELL. SHOWERS DISSIPATE THIS EVENING AND LIGHT SW
WINDS ARE EXPECTED OVERNIGHT.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* MEDIUM CONFIDENCE IN SHRA COVERAGE AND LOCATION.

* MEDIUM CONFIDENCE IN A VERY VERY LOW CHANCE OF TSRA DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY AND SATURDAY...AFTERNOON ISOLATED SHRA/TSRA. AFTERNOON
  LAKE BREEZES.
* SUNDAY AND MONDAY...DRY/VFR.
* TUESDAY...CHANCE OF TSRA.

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KILX 310428
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1128 PM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 730 PM CDT Wed Jul 30 2014

Diurnal clouds quickly fading, leading behind some cirrus left
over from convection in the central Plains, as well as a smoke
layer coming in from the northwest. Have updated the sky grids to
lower the cloud cover, primarily over the next 6 hours or so. This
did not impact the zone forecasts, although an update was sent to
that product to remove the late afternoon period. Temperatures
appear on track and no adjustments needed.

Geelhart


&&

.AVIATION...
ISSUED 1128 PM CDT Wed Jul 30 2014

Not much needs to be changed with the previous TAF set.
Light/variable winds overnight to become more westerly for a time
late Thursday morning into the afternoon, then light/variable
again in the evening. Have a bit of concern with potential for
light shallow fog toward sunrise, though this would have no
substantial depth as the forecast soundings show dry conditions in
the lower levels. Will leave this out for now and continue to
monitor.

Geelhart

&&

.PREV DISCUSSION...
ISSUED 300 PM CDT Wed Jul 30 2014

An upper level trough across the eastern half of the CONUS will
continue to keep Illinois in an unseasonably cool air mass into the
weekend. Chances of spotty showers or storms will continue through
Saturday, then a dry period may develop as into early next week as
upper level ridging advances into IL. Warmer conditions appear in
the far extended as high temps approach normal on Tue and Wed.

SHORT TERM...Tonight through Saturday.

A few showers bubbled up this afternoon northeast of a line from
Bloomington to Mattoon. Any lightning through 230 pm remained in
Indiana closer to the better mid-level instability. RAP sounding
analysis east of Champaign showed only 150-200 J/kg MLCAPE for
storm updraft development in our counties, which supports the
limited vertical development observed visually and on satellite.
We expect any showers in our northeastern forecast area to
dissipate by 00z/7pm, so no precip was included in the evening
grids. The diurnally driven cumulus will dissipate with the
passage of sunset as well, providing clear skies overnight.
Surface winds will become light and variable tonight, creating
favorable radiational cooling conditions. Lows should dip into the
mid to upper 50s in most locations. A few spots could linger in
the low 60s depending on localized surface dew point trends.

Thursday will be a repeat of Wednesday with a few isolated
afternoon showers east-northeast of PIA to BMI to MTO. Highs
will top out in the low 80s with relatively comfortable dew points
around 60F.

Friday and Saturday will feature the passage of stronger 500mb
shortwaves, increasing the potential and coverage of showers and
storms. We still expect mainly 30-40% coverage on both days, but
thunder potential will be higher due to deeper mid-level
instability and increasing moisture. Highs will still remain below
normal in the low 80s through Saturday.

LONG TERM...Sunday through Wednesday.

The upper level low will shift east of Illinois for Sunday through
Monday with upper level ridging providing dry conditions both days.
Slow warming will begin...with highs by Monday approaching the
middle 80s. Storm chances are expected to return on Tuesday and
Wednesday the next series of shortwaves roll over the top of the
ridge in the Plains. No strong to severe weather is anticipated at
this point. A warm front developing north of IL will help
southerly flow bring mid to upper 80s into our forecast area,
which are closer to normal for early Aug.

Shimon


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KILX 310428
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1128 PM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 730 PM CDT Wed Jul 30 2014

Diurnal clouds quickly fading, leading behind some cirrus left
over from convection in the central Plains, as well as a smoke
layer coming in from the northwest. Have updated the sky grids to
lower the cloud cover, primarily over the next 6 hours or so. This
did not impact the zone forecasts, although an update was sent to
that product to remove the late afternoon period. Temperatures
appear on track and no adjustments needed.

Geelhart


&&

.AVIATION...
ISSUED 1128 PM CDT Wed Jul 30 2014

Not much needs to be changed with the previous TAF set.
Light/variable winds overnight to become more westerly for a time
late Thursday morning into the afternoon, then light/variable
again in the evening. Have a bit of concern with potential for
light shallow fog toward sunrise, though this would have no
substantial depth as the forecast soundings show dry conditions in
the lower levels. Will leave this out for now and continue to
monitor.

Geelhart

&&

.PREV DISCUSSION...
ISSUED 300 PM CDT Wed Jul 30 2014

An upper level trough across the eastern half of the CONUS will
continue to keep Illinois in an unseasonably cool air mass into the
weekend. Chances of spotty showers or storms will continue through
Saturday, then a dry period may develop as into early next week as
upper level ridging advances into IL. Warmer conditions appear in
the far extended as high temps approach normal on Tue and Wed.

SHORT TERM...Tonight through Saturday.

A few showers bubbled up this afternoon northeast of a line from
Bloomington to Mattoon. Any lightning through 230 pm remained in
Indiana closer to the better mid-level instability. RAP sounding
analysis east of Champaign showed only 150-200 J/kg MLCAPE for
storm updraft development in our counties, which supports the
limited vertical development observed visually and on satellite.
We expect any showers in our northeastern forecast area to
dissipate by 00z/7pm, so no precip was included in the evening
grids. The diurnally driven cumulus will dissipate with the
passage of sunset as well, providing clear skies overnight.
Surface winds will become light and variable tonight, creating
favorable radiational cooling conditions. Lows should dip into the
mid to upper 50s in most locations. A few spots could linger in
the low 60s depending on localized surface dew point trends.

Thursday will be a repeat of Wednesday with a few isolated
afternoon showers east-northeast of PIA to BMI to MTO. Highs
will top out in the low 80s with relatively comfortable dew points
around 60F.

Friday and Saturday will feature the passage of stronger 500mb
shortwaves, increasing the potential and coverage of showers and
storms. We still expect mainly 30-40% coverage on both days, but
thunder potential will be higher due to deeper mid-level
instability and increasing moisture. Highs will still remain below
normal in the low 80s through Saturday.

LONG TERM...Sunday through Wednesday.

The upper level low will shift east of Illinois for Sunday through
Monday with upper level ridging providing dry conditions both days.
Slow warming will begin...with highs by Monday approaching the
middle 80s. Storm chances are expected to return on Tuesday and
Wednesday the next series of shortwaves roll over the top of the
ridge in the Plains. No strong to severe weather is anticipated at
this point. A warm front developing north of IL will help
southerly flow bring mid to upper 80s into our forecast area,
which are closer to normal for early Aug.

Shimon


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KILX 310428
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1128 PM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 730 PM CDT Wed Jul 30 2014

Diurnal clouds quickly fading, leading behind some cirrus left
over from convection in the central Plains, as well as a smoke
layer coming in from the northwest. Have updated the sky grids to
lower the cloud cover, primarily over the next 6 hours or so. This
did not impact the zone forecasts, although an update was sent to
that product to remove the late afternoon period. Temperatures
appear on track and no adjustments needed.

Geelhart


&&

.AVIATION...
ISSUED 1128 PM CDT Wed Jul 30 2014

Not much needs to be changed with the previous TAF set.
Light/variable winds overnight to become more westerly for a time
late Thursday morning into the afternoon, then light/variable
again in the evening. Have a bit of concern with potential for
light shallow fog toward sunrise, though this would have no
substantial depth as the forecast soundings show dry conditions in
the lower levels. Will leave this out for now and continue to
monitor.

Geelhart

&&

.PREV DISCUSSION...
ISSUED 300 PM CDT Wed Jul 30 2014

An upper level trough across the eastern half of the CONUS will
continue to keep Illinois in an unseasonably cool air mass into the
weekend. Chances of spotty showers or storms will continue through
Saturday, then a dry period may develop as into early next week as
upper level ridging advances into IL. Warmer conditions appear in
the far extended as high temps approach normal on Tue and Wed.

SHORT TERM...Tonight through Saturday.

A few showers bubbled up this afternoon northeast of a line from
Bloomington to Mattoon. Any lightning through 230 pm remained in
Indiana closer to the better mid-level instability. RAP sounding
analysis east of Champaign showed only 150-200 J/kg MLCAPE for
storm updraft development in our counties, which supports the
limited vertical development observed visually and on satellite.
We expect any showers in our northeastern forecast area to
dissipate by 00z/7pm, so no precip was included in the evening
grids. The diurnally driven cumulus will dissipate with the
passage of sunset as well, providing clear skies overnight.
Surface winds will become light and variable tonight, creating
favorable radiational cooling conditions. Lows should dip into the
mid to upper 50s in most locations. A few spots could linger in
the low 60s depending on localized surface dew point trends.

Thursday will be a repeat of Wednesday with a few isolated
afternoon showers east-northeast of PIA to BMI to MTO. Highs
will top out in the low 80s with relatively comfortable dew points
around 60F.

Friday and Saturday will feature the passage of stronger 500mb
shortwaves, increasing the potential and coverage of showers and
storms. We still expect mainly 30-40% coverage on both days, but
thunder potential will be higher due to deeper mid-level
instability and increasing moisture. Highs will still remain below
normal in the low 80s through Saturday.

LONG TERM...Sunday through Wednesday.

The upper level low will shift east of Illinois for Sunday through
Monday with upper level ridging providing dry conditions both days.
Slow warming will begin...with highs by Monday approaching the
middle 80s. Storm chances are expected to return on Tuesday and
Wednesday the next series of shortwaves roll over the top of the
ridge in the Plains. No strong to severe weather is anticipated at
this point. A warm front developing north of IL will help
southerly flow bring mid to upper 80s into our forecast area,
which are closer to normal for early Aug.

Shimon


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KILX 310428
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1128 PM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 730 PM CDT Wed Jul 30 2014

Diurnal clouds quickly fading, leading behind some cirrus left
over from convection in the central Plains, as well as a smoke
layer coming in from the northwest. Have updated the sky grids to
lower the cloud cover, primarily over the next 6 hours or so. This
did not impact the zone forecasts, although an update was sent to
that product to remove the late afternoon period. Temperatures
appear on track and no adjustments needed.

Geelhart


&&

.AVIATION...
ISSUED 1128 PM CDT Wed Jul 30 2014

Not much needs to be changed with the previous TAF set.
Light/variable winds overnight to become more westerly for a time
late Thursday morning into the afternoon, then light/variable
again in the evening. Have a bit of concern with potential for
light shallow fog toward sunrise, though this would have no
substantial depth as the forecast soundings show dry conditions in
the lower levels. Will leave this out for now and continue to
monitor.

Geelhart

&&

.PREV DISCUSSION...
ISSUED 300 PM CDT Wed Jul 30 2014

An upper level trough across the eastern half of the CONUS will
continue to keep Illinois in an unseasonably cool air mass into the
weekend. Chances of spotty showers or storms will continue through
Saturday, then a dry period may develop as into early next week as
upper level ridging advances into IL. Warmer conditions appear in
the far extended as high temps approach normal on Tue and Wed.

SHORT TERM...Tonight through Saturday.

A few showers bubbled up this afternoon northeast of a line from
Bloomington to Mattoon. Any lightning through 230 pm remained in
Indiana closer to the better mid-level instability. RAP sounding
analysis east of Champaign showed only 150-200 J/kg MLCAPE for
storm updraft development in our counties, which supports the
limited vertical development observed visually and on satellite.
We expect any showers in our northeastern forecast area to
dissipate by 00z/7pm, so no precip was included in the evening
grids. The diurnally driven cumulus will dissipate with the
passage of sunset as well, providing clear skies overnight.
Surface winds will become light and variable tonight, creating
favorable radiational cooling conditions. Lows should dip into the
mid to upper 50s in most locations. A few spots could linger in
the low 60s depending on localized surface dew point trends.

Thursday will be a repeat of Wednesday with a few isolated
afternoon showers east-northeast of PIA to BMI to MTO. Highs
will top out in the low 80s with relatively comfortable dew points
around 60F.

Friday and Saturday will feature the passage of stronger 500mb
shortwaves, increasing the potential and coverage of showers and
storms. We still expect mainly 30-40% coverage on both days, but
thunder potential will be higher due to deeper mid-level
instability and increasing moisture. Highs will still remain below
normal in the low 80s through Saturday.

LONG TERM...Sunday through Wednesday.

The upper level low will shift east of Illinois for Sunday through
Monday with upper level ridging providing dry conditions both days.
Slow warming will begin...with highs by Monday approaching the
middle 80s. Storm chances are expected to return on Tuesday and
Wednesday the next series of shortwaves roll over the top of the
ridge in the Plains. No strong to severe weather is anticipated at
this point. A warm front developing north of IL will help
southerly flow bring mid to upper 80s into our forecast area,
which are closer to normal for early Aug.

Shimon


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 310303
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1003 PM CDT WED JUL 30 2014

.DISCUSSION...
844 PM CDT

TEMPERATURES CONTINUE TO HOLD-UP AROUND 70 FOR MOST OF THE AREA.
THE EXCEPTION IS LOCATIONS ADJACENT TO LAKE MICHIGAN WHERE THE
COOLER MARINE ENVIRONMENT HAS BEEN ABLE TO KEEP TEMPS IN THE MID
60S THIS EVENING WITH A CONTINUED ONSHORE FLOW. EXPECT WINDS TO
TURN AROUND FROM THE SOUTH OVERNIGHT. THIS WILL LIKELY KEEP THE
URBAN AREAS A LITTLE WARMER. ELSEWEHERE TEMPS SHUD CONTINUE TO
SLOWLY COOL INTO THE MID/UPR 50S.

BEACHLER

//PREV DISCUSSION...
254 PM CDT

A HIGH AMPLITUDE LONGWAVE PATTERN THAT HAS BEEN IN PLACE FOR THE
PAST FEW DAYS WILL PERSIST FOR THE NEXT FEW DAYS WITH DEEP LONG WAVE
TROUGHING OVER THE ERN CONUS AND AN UPPER LOW CENTER OVER JAMES
BAY...WITH RIDGING OVER THE WRN CONUS.  THE LOCAL AREA WILL REMAIN
UNDER GENERALLY NWLY FLOW ALOFT UNDER THE SWRN PERIPHERY OF THE
UPPER LOW.  THIS WILL ALLOW FOR A SERIES OF WEAK SHORT WAVES TO
RIPPLE THROUGH THE NWLY FLOW ALOFT OVER THE LOCAL AREA.

FOR THE REMAINDER OF THIS AFTERNOON AND THIS EVENING...THE MAIN
CONCERN WILL BE THE LAKE BREEZE BOUNDARY QUICKLY PUSHING INLAND
THROUGH NERN IL AND NWRN IN.  TEMPERATURES WILL DROP OFF SEVERAL
DEGREES WITH THE PASSAGE OF THE BOUNDARY AND LAKEFRONT LOCATIONS
HAVE ALREADY DROPPED INTO THE MIDDLE 60S.  THE ENVIRONMENT AHEAD OF
THE BOUNDARY IS MODESTLY MOIST AND UNSTABLE.  WITH CYCLONIC FLOW
ALOFT...DIURNAL CU HAS BEEN DEVELOPING OVER THE REGION PER THE LATEST
SATELLITE IMAGERY.  AS OF EARLY THIS AFTERNOON...HAVE NOT SEEN ANY
SHRA/TSRA ACTIVITY OVER NRN IL/NWRN IN...BUT THE REGION REMAINS
MODESTLY UNSTABLE WITH DEWPOINTS IN THE MIDDLE TO UPPER 50S.  THERE
WILL STILL BE A CHANCE FOR SOME SHRA/TSRA FOCUSED ALONG THE LAKE
BREEZE BOUNDARY AS WELL AS SOME ISOLD SHRA OR AN EVEN MORE ISOLD TS
OVER THE AREA THROUGH SUNSET.  DURG THE EVENING AND INTO THE
OVERNIGHT HOURS...ANY DIURNAL PCPN WILL DISSIPATE AND AND RESIDUAL
PCPN WILL BE WELL NORTH OF THE AREA INVOF ON OF THE SEEMINGLY
ENDLESS SERIES OF IMPULSES DROPPING THROUGH THE NORTHWEST FLOW.

LITTLE CHANGE IS EXPECTED FOR TOMORROW THROUGH SATURDAY AS THE
SYNOPTIC SCALE PATTERN SHOULD CHANGE LITTLE AND A WEAK GRADIENT
PATTERN WILL PERSIST AT THE SFC.  UNDER PERSISTENT NWLY FLOW
ALOFT...THE SERIES OF WEAK SHORTWAVES WILL CONTINUE TO BRING
PERIODIC CHANCES FOR SCT SHRA AND ISOLD TSRA...WITH THE BETTER
CHANCES FOR TS DURG THE AFTERNOON HOURS.  THE WEAK GRADIENT PATTERN
AT THE SFC SHOULD ALLOW FOR DAILY LAKE BREEZE DEVELOPMENT...WITH THE
MAIN QUESTION BEING HOW FAR INLAND A LAKE BREEZE WILL PENETRATE.
CERTAINLY...IT IS LIKELY THAT LAKEFRONT LOCATIONS WILL TURN COOLER
IN THE AFTERNOON...BUT IT IS LESS CERTAIN HOW FAR INLAND THE LAKE
COOLING WILL PENETRATE.  SO...WILL KEEP THE MAX TEMP FORECAST A BIT
ON THE CONSERVATIVE SIDE AS FAR AS LAKE INFLUENCE IS CONCERNED AND
LIMIT THE COOLING TO THE IMMEDIATE LAKEFRONT AND ALLOW MAX TEMPS TO
BE MORE REPRESENTATIVE OF THE LARGE SCALE PATTERN.  UNDER THE COOL
NWLY FLOW ALOFT...HIGHS WILL REMAIN A FEW DEGREES BELOW NORMAL INTO
THE WEEKEND WITH HIGHS AROUND 80F OR SO.  TIMING OF PERIODS OF PCPN
WILL BE LESS CERTAIN THAN THE TEMPERATURE TRENDS FOR THE NEXT FEW
DAYS AND WILL GENERALLY BE DEPENDENT ON THE TIMING OF SHORTWAVE
ENERGY DROPPING THROUGH THE NWLY FLOW ALOFT.  SO...WHILE NO DAY IN
THE SHORT TERM FORECAST PERIOD WILL BE A TOTAL WASHOUT...THERE
SHOULD BE PERIODS OF SCT SHRA AND ISOLD TSRA.

THE LONGER RANGE GUIDANCE IS IN GENERALLY GOOD AGREEMENT ON THE
UPPER LEVEL PATTERN BECOMING MORE PROGRESSIVE THROUGH THE WEEKEND.
THIS WILL INITIATE A WARMING TREND AS THE UPPER LEVEL RIDGING MOVES
OUT OVER THE WESTERN PLAINS ON SUNDAY WHILE THE UPPER LOW OVER JAMES
BAY KICKS OUT TO THE NORTHEAST...LEAVING WEAKER LONGWAVE TROUGHING
OVER THE ERN CONUS.  SUNDAY SHOULD BE A TRANSITIONAL DAY...WITH
INLAND TEMPS A LITTLE HIGHER...BUT A WEAK GRADIENT PERSISTING AT THE
SURFACE WILL ALLOW FOR ANOTHER LAKE BREEZE DAY AND COOLER CONDITIONS
NEAR THE LAKE. RISING HEIGHTS OVER THE MIDWEST SHOULD ALLOW FOR MAX
TEMPS TO CLIMB INTO THE MIDDLE 80S BY MONDAY.

MORE UNCERTAINTY WILL CREEP INTO THE FORECAST DURING THE EXTENDED
FORECAST PERIOD AS FLOW BECOMES MORE ZONAL OVER THE MIDWEST.  IN THE
INCREASINGLY ZONAL FLOW...SHORT WAVE STRENGTH AND TIMING WILL BECOME
MORE UNCERTAIN...SO...CONFIDENCE IN THE SENSIBLE WEATHER FORECAST
WILL INCREASE WITH TIME THROUGH THE EXTENDED FORECAST PERIOD.
HOWEVER...THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THE WARMING
TREND COULD BE BRIEF AS A WEAK UPPER LOW HANGS BACK OVER THE LOWER
MISSISSIPPI VALLEY THROUGH THE PERIOD AND THE UPPER RIDGING WILL NOT
BUILD ANY FARTHER EAST THAN THE CENTRAL PLAINS.  ALSO...THE SFC
PATTERN SHOULD REMAIN WEAK...SO DAILY LAKE BREEZE DEVELOPMENT WILL
BE LIKELY AS WELL. THE TREND FOR THE EXTEDNED FORECAST PERIOD IS
SHAPPING UP FOR MORE BELOW NORMAL TEMPERATURES WITH PERIODIC CHANCES
FOR AT LEAST SOME LIGHT PCPN.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* ISOLATED SHRA/TSRA THURSDAY AFTERNOON. CMS

//DISCUSSION...UPDATED 00Z...

A LAKE BREEZE HAS MOVED WELL WEST OF ORD/MDW LATE THIS AFTERNOON
AND WILL CONTINUE WEST UNTIL IT DISSIPATES THIS EVENING. THE
GRADIENT WILL BE QUITE WEAK TONIGHT AND WINDS WILL EVENTUALLY
BECOME LIGHT AND VARIABLE AND LIKELY CALM IN MANY LOCATIONS. WINDS
WILL BECOME LIGHT WEST/SOUTHWEST AFTER SUNRISE AND REMAIN WESTERLY
THURSDAY WITH SPEEDS INCREASING TO 10-12KTS WITH A FEW HIGHER
GUSTS POSSIBLE IN THE AFTERNOON. WIND SPEEDS APPEAR STRONG ENOUGH
TO PREVENT A LAKE BREEZE FROM REACHING ORD/MDW...BUT A LAKE BREEZE
MAY STILL FORM NEAR THE LAKE.

CU FIELD IS QUICKLY DISSIPATING THIS EVENING AND NOT EXPECTING ANY
ADDITIONAL SHOWERS. SHOWERS AND THUNDERSTORMS OVER NORTHERN WI
WILL MOVE SOUTH THIS EVENING BUT ARE EXPECTED TO DISSIPATE BEFORE
REACHING NORTHERN IL WITH JUST FEW/SCT MID CLOUDS OVERNIGHT.
ISOLATED SHOWERS/THUNDERSTORMS ARE POSSIBLE THURSDAY AFTERNOON
INTO EARLY EVENING.

WITH THE LIGHT WINDS...TEMPS WILL LIKELY COOL TOWARD THE DEWPOINTS
OVERNIGHT AND TOWARD MORNING WITH SOME LIGHT/SHALLOW GROUND FOG
POSSIBLE IN THE USUAL SPOTS AND ADDED FOG MENTION TO DPA. CMS

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* LOW FOR ISOLATED SHRA/TSRA THURSDAY AFTERNOON. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY AND SATURDAY...AFTERNOON ISOLATED SHRA/TSRA. AFTERNOON
  LAKE BREEZES.
* SUNDAY AND MONDAY...DRY/VFR.
* TUESDAY...CHANCE OF TSRA.

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 310303
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1003 PM CDT WED JUL 30 2014

.DISCUSSION...
844 PM CDT

TEMPERATURES CONTINUE TO HOLD-UP AROUND 70 FOR MOST OF THE AREA.
THE EXCEPTION IS LOCATIONS ADJACENT TO LAKE MICHIGAN WHERE THE
COOLER MARINE ENVIRONMENT HAS BEEN ABLE TO KEEP TEMPS IN THE MID
60S THIS EVENING WITH A CONTINUED ONSHORE FLOW. EXPECT WINDS TO
TURN AROUND FROM THE SOUTH OVERNIGHT. THIS WILL LIKELY KEEP THE
URBAN AREAS A LITTLE WARMER. ELSEWEHERE TEMPS SHUD CONTINUE TO
SLOWLY COOL INTO THE MID/UPR 50S.

BEACHLER

//PREV DISCUSSION...
254 PM CDT

A HIGH AMPLITUDE LONGWAVE PATTERN THAT HAS BEEN IN PLACE FOR THE
PAST FEW DAYS WILL PERSIST FOR THE NEXT FEW DAYS WITH DEEP LONG WAVE
TROUGHING OVER THE ERN CONUS AND AN UPPER LOW CENTER OVER JAMES
BAY...WITH RIDGING OVER THE WRN CONUS.  THE LOCAL AREA WILL REMAIN
UNDER GENERALLY NWLY FLOW ALOFT UNDER THE SWRN PERIPHERY OF THE
UPPER LOW.  THIS WILL ALLOW FOR A SERIES OF WEAK SHORT WAVES TO
RIPPLE THROUGH THE NWLY FLOW ALOFT OVER THE LOCAL AREA.

FOR THE REMAINDER OF THIS AFTERNOON AND THIS EVENING...THE MAIN
CONCERN WILL BE THE LAKE BREEZE BOUNDARY QUICKLY PUSHING INLAND
THROUGH NERN IL AND NWRN IN.  TEMPERATURES WILL DROP OFF SEVERAL
DEGREES WITH THE PASSAGE OF THE BOUNDARY AND LAKEFRONT LOCATIONS
HAVE ALREADY DROPPED INTO THE MIDDLE 60S.  THE ENVIRONMENT AHEAD OF
THE BOUNDARY IS MODESTLY MOIST AND UNSTABLE.  WITH CYCLONIC FLOW
ALOFT...DIURNAL CU HAS BEEN DEVELOPING OVER THE REGION PER THE LATEST
SATELLITE IMAGERY.  AS OF EARLY THIS AFTERNOON...HAVE NOT SEEN ANY
SHRA/TSRA ACTIVITY OVER NRN IL/NWRN IN...BUT THE REGION REMAINS
MODESTLY UNSTABLE WITH DEWPOINTS IN THE MIDDLE TO UPPER 50S.  THERE
WILL STILL BE A CHANCE FOR SOME SHRA/TSRA FOCUSED ALONG THE LAKE
BREEZE BOUNDARY AS WELL AS SOME ISOLD SHRA OR AN EVEN MORE ISOLD TS
OVER THE AREA THROUGH SUNSET.  DURG THE EVENING AND INTO THE
OVERNIGHT HOURS...ANY DIURNAL PCPN WILL DISSIPATE AND AND RESIDUAL
PCPN WILL BE WELL NORTH OF THE AREA INVOF ON OF THE SEEMINGLY
ENDLESS SERIES OF IMPULSES DROPPING THROUGH THE NORTHWEST FLOW.

LITTLE CHANGE IS EXPECTED FOR TOMORROW THROUGH SATURDAY AS THE
SYNOPTIC SCALE PATTERN SHOULD CHANGE LITTLE AND A WEAK GRADIENT
PATTERN WILL PERSIST AT THE SFC.  UNDER PERSISTENT NWLY FLOW
ALOFT...THE SERIES OF WEAK SHORTWAVES WILL CONTINUE TO BRING
PERIODIC CHANCES FOR SCT SHRA AND ISOLD TSRA...WITH THE BETTER
CHANCES FOR TS DURG THE AFTERNOON HOURS.  THE WEAK GRADIENT PATTERN
AT THE SFC SHOULD ALLOW FOR DAILY LAKE BREEZE DEVELOPMENT...WITH THE
MAIN QUESTION BEING HOW FAR INLAND A LAKE BREEZE WILL PENETRATE.
CERTAINLY...IT IS LIKELY THAT LAKEFRONT LOCATIONS WILL TURN COOLER
IN THE AFTERNOON...BUT IT IS LESS CERTAIN HOW FAR INLAND THE LAKE
COOLING WILL PENETRATE.  SO...WILL KEEP THE MAX TEMP FORECAST A BIT
ON THE CONSERVATIVE SIDE AS FAR AS LAKE INFLUENCE IS CONCERNED AND
LIMIT THE COOLING TO THE IMMEDIATE LAKEFRONT AND ALLOW MAX TEMPS TO
BE MORE REPRESENTATIVE OF THE LARGE SCALE PATTERN.  UNDER THE COOL
NWLY FLOW ALOFT...HIGHS WILL REMAIN A FEW DEGREES BELOW NORMAL INTO
THE WEEKEND WITH HIGHS AROUND 80F OR SO.  TIMING OF PERIODS OF PCPN
WILL BE LESS CERTAIN THAN THE TEMPERATURE TRENDS FOR THE NEXT FEW
DAYS AND WILL GENERALLY BE DEPENDENT ON THE TIMING OF SHORTWAVE
ENERGY DROPPING THROUGH THE NWLY FLOW ALOFT.  SO...WHILE NO DAY IN
THE SHORT TERM FORECAST PERIOD WILL BE A TOTAL WASHOUT...THERE
SHOULD BE PERIODS OF SCT SHRA AND ISOLD TSRA.

THE LONGER RANGE GUIDANCE IS IN GENERALLY GOOD AGREEMENT ON THE
UPPER LEVEL PATTERN BECOMING MORE PROGRESSIVE THROUGH THE WEEKEND.
THIS WILL INITIATE A WARMING TREND AS THE UPPER LEVEL RIDGING MOVES
OUT OVER THE WESTERN PLAINS ON SUNDAY WHILE THE UPPER LOW OVER JAMES
BAY KICKS OUT TO THE NORTHEAST...LEAVING WEAKER LONGWAVE TROUGHING
OVER THE ERN CONUS.  SUNDAY SHOULD BE A TRANSITIONAL DAY...WITH
INLAND TEMPS A LITTLE HIGHER...BUT A WEAK GRADIENT PERSISTING AT THE
SURFACE WILL ALLOW FOR ANOTHER LAKE BREEZE DAY AND COOLER CONDITIONS
NEAR THE LAKE. RISING HEIGHTS OVER THE MIDWEST SHOULD ALLOW FOR MAX
TEMPS TO CLIMB INTO THE MIDDLE 80S BY MONDAY.

MORE UNCERTAINTY WILL CREEP INTO THE FORECAST DURING THE EXTENDED
FORECAST PERIOD AS FLOW BECOMES MORE ZONAL OVER THE MIDWEST.  IN THE
INCREASINGLY ZONAL FLOW...SHORT WAVE STRENGTH AND TIMING WILL BECOME
MORE UNCERTAIN...SO...CONFIDENCE IN THE SENSIBLE WEATHER FORECAST
WILL INCREASE WITH TIME THROUGH THE EXTENDED FORECAST PERIOD.
HOWEVER...THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THE WARMING
TREND COULD BE BRIEF AS A WEAK UPPER LOW HANGS BACK OVER THE LOWER
MISSISSIPPI VALLEY THROUGH THE PERIOD AND THE UPPER RIDGING WILL NOT
BUILD ANY FARTHER EAST THAN THE CENTRAL PLAINS.  ALSO...THE SFC
PATTERN SHOULD REMAIN WEAK...SO DAILY LAKE BREEZE DEVELOPMENT WILL
BE LIKELY AS WELL. THE TREND FOR THE EXTEDNED FORECAST PERIOD IS
SHAPPING UP FOR MORE BELOW NORMAL TEMPERATURES WITH PERIODIC CHANCES
FOR AT LEAST SOME LIGHT PCPN.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* ISOLATED SHRA/TSRA THURSDAY AFTERNOON. CMS

//DISCUSSION...UPDATED 00Z...

A LAKE BREEZE HAS MOVED WELL WEST OF ORD/MDW LATE THIS AFTERNOON
AND WILL CONTINUE WEST UNTIL IT DISSIPATES THIS EVENING. THE
GRADIENT WILL BE QUITE WEAK TONIGHT AND WINDS WILL EVENTUALLY
BECOME LIGHT AND VARIABLE AND LIKELY CALM IN MANY LOCATIONS. WINDS
WILL BECOME LIGHT WEST/SOUTHWEST AFTER SUNRISE AND REMAIN WESTERLY
THURSDAY WITH SPEEDS INCREASING TO 10-12KTS WITH A FEW HIGHER
GUSTS POSSIBLE IN THE AFTERNOON. WIND SPEEDS APPEAR STRONG ENOUGH
TO PREVENT A LAKE BREEZE FROM REACHING ORD/MDW...BUT A LAKE BREEZE
MAY STILL FORM NEAR THE LAKE.

CU FIELD IS QUICKLY DISSIPATING THIS EVENING AND NOT EXPECTING ANY
ADDITIONAL SHOWERS. SHOWERS AND THUNDERSTORMS OVER NORTHERN WI
WILL MOVE SOUTH THIS EVENING BUT ARE EXPECTED TO DISSIPATE BEFORE
REACHING NORTHERN IL WITH JUST FEW/SCT MID CLOUDS OVERNIGHT.
ISOLATED SHOWERS/THUNDERSTORMS ARE POSSIBLE THURSDAY AFTERNOON
INTO EARLY EVENING.

WITH THE LIGHT WINDS...TEMPS WILL LIKELY COOL TOWARD THE DEWPOINTS
OVERNIGHT AND TOWARD MORNING WITH SOME LIGHT/SHALLOW GROUND FOG
POSSIBLE IN THE USUAL SPOTS AND ADDED FOG MENTION TO DPA. CMS

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* LOW FOR ISOLATED SHRA/TSRA THURSDAY AFTERNOON. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY AND SATURDAY...AFTERNOON ISOLATED SHRA/TSRA. AFTERNOON
  LAKE BREEZES.
* SUNDAY AND MONDAY...DRY/VFR.
* TUESDAY...CHANCE OF TSRA.

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 310303
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1003 PM CDT WED JUL 30 2014

.DISCUSSION...
844 PM CDT

TEMPERATURES CONTINUE TO HOLD-UP AROUND 70 FOR MOST OF THE AREA.
THE EXCEPTION IS LOCATIONS ADJACENT TO LAKE MICHIGAN WHERE THE
COOLER MARINE ENVIRONMENT HAS BEEN ABLE TO KEEP TEMPS IN THE MID
60S THIS EVENING WITH A CONTINUED ONSHORE FLOW. EXPECT WINDS TO
TURN AROUND FROM THE SOUTH OVERNIGHT. THIS WILL LIKELY KEEP THE
URBAN AREAS A LITTLE WARMER. ELSEWEHERE TEMPS SHUD CONTINUE TO
SLOWLY COOL INTO THE MID/UPR 50S.

BEACHLER

//PREV DISCUSSION...
254 PM CDT

A HIGH AMPLITUDE LONGWAVE PATTERN THAT HAS BEEN IN PLACE FOR THE
PAST FEW DAYS WILL PERSIST FOR THE NEXT FEW DAYS WITH DEEP LONG WAVE
TROUGHING OVER THE ERN CONUS AND AN UPPER LOW CENTER OVER JAMES
BAY...WITH RIDGING OVER THE WRN CONUS.  THE LOCAL AREA WILL REMAIN
UNDER GENERALLY NWLY FLOW ALOFT UNDER THE SWRN PERIPHERY OF THE
UPPER LOW.  THIS WILL ALLOW FOR A SERIES OF WEAK SHORT WAVES TO
RIPPLE THROUGH THE NWLY FLOW ALOFT OVER THE LOCAL AREA.

FOR THE REMAINDER OF THIS AFTERNOON AND THIS EVENING...THE MAIN
CONCERN WILL BE THE LAKE BREEZE BOUNDARY QUICKLY PUSHING INLAND
THROUGH NERN IL AND NWRN IN.  TEMPERATURES WILL DROP OFF SEVERAL
DEGREES WITH THE PASSAGE OF THE BOUNDARY AND LAKEFRONT LOCATIONS
HAVE ALREADY DROPPED INTO THE MIDDLE 60S.  THE ENVIRONMENT AHEAD OF
THE BOUNDARY IS MODESTLY MOIST AND UNSTABLE.  WITH CYCLONIC FLOW
ALOFT...DIURNAL CU HAS BEEN DEVELOPING OVER THE REGION PER THE LATEST
SATELLITE IMAGERY.  AS OF EARLY THIS AFTERNOON...HAVE NOT SEEN ANY
SHRA/TSRA ACTIVITY OVER NRN IL/NWRN IN...BUT THE REGION REMAINS
MODESTLY UNSTABLE WITH DEWPOINTS IN THE MIDDLE TO UPPER 50S.  THERE
WILL STILL BE A CHANCE FOR SOME SHRA/TSRA FOCUSED ALONG THE LAKE
BREEZE BOUNDARY AS WELL AS SOME ISOLD SHRA OR AN EVEN MORE ISOLD TS
OVER THE AREA THROUGH SUNSET.  DURG THE EVENING AND INTO THE
OVERNIGHT HOURS...ANY DIURNAL PCPN WILL DISSIPATE AND AND RESIDUAL
PCPN WILL BE WELL NORTH OF THE AREA INVOF ON OF THE SEEMINGLY
ENDLESS SERIES OF IMPULSES DROPPING THROUGH THE NORTHWEST FLOW.

LITTLE CHANGE IS EXPECTED FOR TOMORROW THROUGH SATURDAY AS THE
SYNOPTIC SCALE PATTERN SHOULD CHANGE LITTLE AND A WEAK GRADIENT
PATTERN WILL PERSIST AT THE SFC.  UNDER PERSISTENT NWLY FLOW
ALOFT...THE SERIES OF WEAK SHORTWAVES WILL CONTINUE TO BRING
PERIODIC CHANCES FOR SCT SHRA AND ISOLD TSRA...WITH THE BETTER
CHANCES FOR TS DURG THE AFTERNOON HOURS.  THE WEAK GRADIENT PATTERN
AT THE SFC SHOULD ALLOW FOR DAILY LAKE BREEZE DEVELOPMENT...WITH THE
MAIN QUESTION BEING HOW FAR INLAND A LAKE BREEZE WILL PENETRATE.
CERTAINLY...IT IS LIKELY THAT LAKEFRONT LOCATIONS WILL TURN COOLER
IN THE AFTERNOON...BUT IT IS LESS CERTAIN HOW FAR INLAND THE LAKE
COOLING WILL PENETRATE.  SO...WILL KEEP THE MAX TEMP FORECAST A BIT
ON THE CONSERVATIVE SIDE AS FAR AS LAKE INFLUENCE IS CONCERNED AND
LIMIT THE COOLING TO THE IMMEDIATE LAKEFRONT AND ALLOW MAX TEMPS TO
BE MORE REPRESENTATIVE OF THE LARGE SCALE PATTERN.  UNDER THE COOL
NWLY FLOW ALOFT...HIGHS WILL REMAIN A FEW DEGREES BELOW NORMAL INTO
THE WEEKEND WITH HIGHS AROUND 80F OR SO.  TIMING OF PERIODS OF PCPN
WILL BE LESS CERTAIN THAN THE TEMPERATURE TRENDS FOR THE NEXT FEW
DAYS AND WILL GENERALLY BE DEPENDENT ON THE TIMING OF SHORTWAVE
ENERGY DROPPING THROUGH THE NWLY FLOW ALOFT.  SO...WHILE NO DAY IN
THE SHORT TERM FORECAST PERIOD WILL BE A TOTAL WASHOUT...THERE
SHOULD BE PERIODS OF SCT SHRA AND ISOLD TSRA.

THE LONGER RANGE GUIDANCE IS IN GENERALLY GOOD AGREEMENT ON THE
UPPER LEVEL PATTERN BECOMING MORE PROGRESSIVE THROUGH THE WEEKEND.
THIS WILL INITIATE A WARMING TREND AS THE UPPER LEVEL RIDGING MOVES
OUT OVER THE WESTERN PLAINS ON SUNDAY WHILE THE UPPER LOW OVER JAMES
BAY KICKS OUT TO THE NORTHEAST...LEAVING WEAKER LONGWAVE TROUGHING
OVER THE ERN CONUS.  SUNDAY SHOULD BE A TRANSITIONAL DAY...WITH
INLAND TEMPS A LITTLE HIGHER...BUT A WEAK GRADIENT PERSISTING AT THE
SURFACE WILL ALLOW FOR ANOTHER LAKE BREEZE DAY AND COOLER CONDITIONS
NEAR THE LAKE. RISING HEIGHTS OVER THE MIDWEST SHOULD ALLOW FOR MAX
TEMPS TO CLIMB INTO THE MIDDLE 80S BY MONDAY.

MORE UNCERTAINTY WILL CREEP INTO THE FORECAST DURING THE EXTENDED
FORECAST PERIOD AS FLOW BECOMES MORE ZONAL OVER THE MIDWEST.  IN THE
INCREASINGLY ZONAL FLOW...SHORT WAVE STRENGTH AND TIMING WILL BECOME
MORE UNCERTAIN...SO...CONFIDENCE IN THE SENSIBLE WEATHER FORECAST
WILL INCREASE WITH TIME THROUGH THE EXTENDED FORECAST PERIOD.
HOWEVER...THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THE WARMING
TREND COULD BE BRIEF AS A WEAK UPPER LOW HANGS BACK OVER THE LOWER
MISSISSIPPI VALLEY THROUGH THE PERIOD AND THE UPPER RIDGING WILL NOT
BUILD ANY FARTHER EAST THAN THE CENTRAL PLAINS.  ALSO...THE SFC
PATTERN SHOULD REMAIN WEAK...SO DAILY LAKE BREEZE DEVELOPMENT WILL
BE LIKELY AS WELL. THE TREND FOR THE EXTEDNED FORECAST PERIOD IS
SHAPPING UP FOR MORE BELOW NORMAL TEMPERATURES WITH PERIODIC CHANCES
FOR AT LEAST SOME LIGHT PCPN.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* ISOLATED SHRA/TSRA THURSDAY AFTERNOON. CMS

//DISCUSSION...UPDATED 00Z...

A LAKE BREEZE HAS MOVED WELL WEST OF ORD/MDW LATE THIS AFTERNOON
AND WILL CONTINUE WEST UNTIL IT DISSIPATES THIS EVENING. THE
GRADIENT WILL BE QUITE WEAK TONIGHT AND WINDS WILL EVENTUALLY
BECOME LIGHT AND VARIABLE AND LIKELY CALM IN MANY LOCATIONS. WINDS
WILL BECOME LIGHT WEST/SOUTHWEST AFTER SUNRISE AND REMAIN WESTERLY
THURSDAY WITH SPEEDS INCREASING TO 10-12KTS WITH A FEW HIGHER
GUSTS POSSIBLE IN THE AFTERNOON. WIND SPEEDS APPEAR STRONG ENOUGH
TO PREVENT A LAKE BREEZE FROM REACHING ORD/MDW...BUT A LAKE BREEZE
MAY STILL FORM NEAR THE LAKE.

CU FIELD IS QUICKLY DISSIPATING THIS EVENING AND NOT EXPECTING ANY
ADDITIONAL SHOWERS. SHOWERS AND THUNDERSTORMS OVER NORTHERN WI
WILL MOVE SOUTH THIS EVENING BUT ARE EXPECTED TO DISSIPATE BEFORE
REACHING NORTHERN IL WITH JUST FEW/SCT MID CLOUDS OVERNIGHT.
ISOLATED SHOWERS/THUNDERSTORMS ARE POSSIBLE THURSDAY AFTERNOON
INTO EARLY EVENING.

WITH THE LIGHT WINDS...TEMPS WILL LIKELY COOL TOWARD THE DEWPOINTS
OVERNIGHT AND TOWARD MORNING WITH SOME LIGHT/SHALLOW GROUND FOG
POSSIBLE IN THE USUAL SPOTS AND ADDED FOG MENTION TO DPA. CMS

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* LOW FOR ISOLATED SHRA/TSRA THURSDAY AFTERNOON. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY AND SATURDAY...AFTERNOON ISOLATED SHRA/TSRA. AFTERNOON
  LAKE BREEZES.
* SUNDAY AND MONDAY...DRY/VFR.
* TUESDAY...CHANCE OF TSRA.

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 310303
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1003 PM CDT WED JUL 30 2014

.DISCUSSION...
844 PM CDT

TEMPERATURES CONTINUE TO HOLD-UP AROUND 70 FOR MOST OF THE AREA.
THE EXCEPTION IS LOCATIONS ADJACENT TO LAKE MICHIGAN WHERE THE
COOLER MARINE ENVIRONMENT HAS BEEN ABLE TO KEEP TEMPS IN THE MID
60S THIS EVENING WITH A CONTINUED ONSHORE FLOW. EXPECT WINDS TO
TURN AROUND FROM THE SOUTH OVERNIGHT. THIS WILL LIKELY KEEP THE
URBAN AREAS A LITTLE WARMER. ELSEWEHERE TEMPS SHUD CONTINUE TO
SLOWLY COOL INTO THE MID/UPR 50S.

BEACHLER

//PREV DISCUSSION...
254 PM CDT

A HIGH AMPLITUDE LONGWAVE PATTERN THAT HAS BEEN IN PLACE FOR THE
PAST FEW DAYS WILL PERSIST FOR THE NEXT FEW DAYS WITH DEEP LONG WAVE
TROUGHING OVER THE ERN CONUS AND AN UPPER LOW CENTER OVER JAMES
BAY...WITH RIDGING OVER THE WRN CONUS.  THE LOCAL AREA WILL REMAIN
UNDER GENERALLY NWLY FLOW ALOFT UNDER THE SWRN PERIPHERY OF THE
UPPER LOW.  THIS WILL ALLOW FOR A SERIES OF WEAK SHORT WAVES TO
RIPPLE THROUGH THE NWLY FLOW ALOFT OVER THE LOCAL AREA.

FOR THE REMAINDER OF THIS AFTERNOON AND THIS EVENING...THE MAIN
CONCERN WILL BE THE LAKE BREEZE BOUNDARY QUICKLY PUSHING INLAND
THROUGH NERN IL AND NWRN IN.  TEMPERATURES WILL DROP OFF SEVERAL
DEGREES WITH THE PASSAGE OF THE BOUNDARY AND LAKEFRONT LOCATIONS
HAVE ALREADY DROPPED INTO THE MIDDLE 60S.  THE ENVIRONMENT AHEAD OF
THE BOUNDARY IS MODESTLY MOIST AND UNSTABLE.  WITH CYCLONIC FLOW
ALOFT...DIURNAL CU HAS BEEN DEVELOPING OVER THE REGION PER THE LATEST
SATELLITE IMAGERY.  AS OF EARLY THIS AFTERNOON...HAVE NOT SEEN ANY
SHRA/TSRA ACTIVITY OVER NRN IL/NWRN IN...BUT THE REGION REMAINS
MODESTLY UNSTABLE WITH DEWPOINTS IN THE MIDDLE TO UPPER 50S.  THERE
WILL STILL BE A CHANCE FOR SOME SHRA/TSRA FOCUSED ALONG THE LAKE
BREEZE BOUNDARY AS WELL AS SOME ISOLD SHRA OR AN EVEN MORE ISOLD TS
OVER THE AREA THROUGH SUNSET.  DURG THE EVENING AND INTO THE
OVERNIGHT HOURS...ANY DIURNAL PCPN WILL DISSIPATE AND AND RESIDUAL
PCPN WILL BE WELL NORTH OF THE AREA INVOF ON OF THE SEEMINGLY
ENDLESS SERIES OF IMPULSES DROPPING THROUGH THE NORTHWEST FLOW.

LITTLE CHANGE IS EXPECTED FOR TOMORROW THROUGH SATURDAY AS THE
SYNOPTIC SCALE PATTERN SHOULD CHANGE LITTLE AND A WEAK GRADIENT
PATTERN WILL PERSIST AT THE SFC.  UNDER PERSISTENT NWLY FLOW
ALOFT...THE SERIES OF WEAK SHORTWAVES WILL CONTINUE TO BRING
PERIODIC CHANCES FOR SCT SHRA AND ISOLD TSRA...WITH THE BETTER
CHANCES FOR TS DURG THE AFTERNOON HOURS.  THE WEAK GRADIENT PATTERN
AT THE SFC SHOULD ALLOW FOR DAILY LAKE BREEZE DEVELOPMENT...WITH THE
MAIN QUESTION BEING HOW FAR INLAND A LAKE BREEZE WILL PENETRATE.
CERTAINLY...IT IS LIKELY THAT LAKEFRONT LOCATIONS WILL TURN COOLER
IN THE AFTERNOON...BUT IT IS LESS CERTAIN HOW FAR INLAND THE LAKE
COOLING WILL PENETRATE.  SO...WILL KEEP THE MAX TEMP FORECAST A BIT
ON THE CONSERVATIVE SIDE AS FAR AS LAKE INFLUENCE IS CONCERNED AND
LIMIT THE COOLING TO THE IMMEDIATE LAKEFRONT AND ALLOW MAX TEMPS TO
BE MORE REPRESENTATIVE OF THE LARGE SCALE PATTERN.  UNDER THE COOL
NWLY FLOW ALOFT...HIGHS WILL REMAIN A FEW DEGREES BELOW NORMAL INTO
THE WEEKEND WITH HIGHS AROUND 80F OR SO.  TIMING OF PERIODS OF PCPN
WILL BE LESS CERTAIN THAN THE TEMPERATURE TRENDS FOR THE NEXT FEW
DAYS AND WILL GENERALLY BE DEPENDENT ON THE TIMING OF SHORTWAVE
ENERGY DROPPING THROUGH THE NWLY FLOW ALOFT.  SO...WHILE NO DAY IN
THE SHORT TERM FORECAST PERIOD WILL BE A TOTAL WASHOUT...THERE
SHOULD BE PERIODS OF SCT SHRA AND ISOLD TSRA.

THE LONGER RANGE GUIDANCE IS IN GENERALLY GOOD AGREEMENT ON THE
UPPER LEVEL PATTERN BECOMING MORE PROGRESSIVE THROUGH THE WEEKEND.
THIS WILL INITIATE A WARMING TREND AS THE UPPER LEVEL RIDGING MOVES
OUT OVER THE WESTERN PLAINS ON SUNDAY WHILE THE UPPER LOW OVER JAMES
BAY KICKS OUT TO THE NORTHEAST...LEAVING WEAKER LONGWAVE TROUGHING
OVER THE ERN CONUS.  SUNDAY SHOULD BE A TRANSITIONAL DAY...WITH
INLAND TEMPS A LITTLE HIGHER...BUT A WEAK GRADIENT PERSISTING AT THE
SURFACE WILL ALLOW FOR ANOTHER LAKE BREEZE DAY AND COOLER CONDITIONS
NEAR THE LAKE. RISING HEIGHTS OVER THE MIDWEST SHOULD ALLOW FOR MAX
TEMPS TO CLIMB INTO THE MIDDLE 80S BY MONDAY.

MORE UNCERTAINTY WILL CREEP INTO THE FORECAST DURING THE EXTENDED
FORECAST PERIOD AS FLOW BECOMES MORE ZONAL OVER THE MIDWEST.  IN THE
INCREASINGLY ZONAL FLOW...SHORT WAVE STRENGTH AND TIMING WILL BECOME
MORE UNCERTAIN...SO...CONFIDENCE IN THE SENSIBLE WEATHER FORECAST
WILL INCREASE WITH TIME THROUGH THE EXTENDED FORECAST PERIOD.
HOWEVER...THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THE WARMING
TREND COULD BE BRIEF AS A WEAK UPPER LOW HANGS BACK OVER THE LOWER
MISSISSIPPI VALLEY THROUGH THE PERIOD AND THE UPPER RIDGING WILL NOT
BUILD ANY FARTHER EAST THAN THE CENTRAL PLAINS.  ALSO...THE SFC
PATTERN SHOULD REMAIN WEAK...SO DAILY LAKE BREEZE DEVELOPMENT WILL
BE LIKELY AS WELL. THE TREND FOR THE EXTEDNED FORECAST PERIOD IS
SHAPPING UP FOR MORE BELOW NORMAL TEMPERATURES WITH PERIODIC CHANCES
FOR AT LEAST SOME LIGHT PCPN.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* ISOLATED SHRA/TSRA THURSDAY AFTERNOON. CMS

//DISCUSSION...UPDATED 00Z...

A LAKE BREEZE HAS MOVED WELL WEST OF ORD/MDW LATE THIS AFTERNOON
AND WILL CONTINUE WEST UNTIL IT DISSIPATES THIS EVENING. THE
GRADIENT WILL BE QUITE WEAK TONIGHT AND WINDS WILL EVENTUALLY
BECOME LIGHT AND VARIABLE AND LIKELY CALM IN MANY LOCATIONS. WINDS
WILL BECOME LIGHT WEST/SOUTHWEST AFTER SUNRISE AND REMAIN WESTERLY
THURSDAY WITH SPEEDS INCREASING TO 10-12KTS WITH A FEW HIGHER
GUSTS POSSIBLE IN THE AFTERNOON. WIND SPEEDS APPEAR STRONG ENOUGH
TO PREVENT A LAKE BREEZE FROM REACHING ORD/MDW...BUT A LAKE BREEZE
MAY STILL FORM NEAR THE LAKE.

CU FIELD IS QUICKLY DISSIPATING THIS EVENING AND NOT EXPECTING ANY
ADDITIONAL SHOWERS. SHOWERS AND THUNDERSTORMS OVER NORTHERN WI
WILL MOVE SOUTH THIS EVENING BUT ARE EXPECTED TO DISSIPATE BEFORE
REACHING NORTHERN IL WITH JUST FEW/SCT MID CLOUDS OVERNIGHT.
ISOLATED SHOWERS/THUNDERSTORMS ARE POSSIBLE THURSDAY AFTERNOON
INTO EARLY EVENING.

WITH THE LIGHT WINDS...TEMPS WILL LIKELY COOL TOWARD THE DEWPOINTS
OVERNIGHT AND TOWARD MORNING WITH SOME LIGHT/SHALLOW GROUND FOG
POSSIBLE IN THE USUAL SPOTS AND ADDED FOG MENTION TO DPA. CMS

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* LOW FOR ISOLATED SHRA/TSRA THURSDAY AFTERNOON. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY AND SATURDAY...AFTERNOON ISOLATED SHRA/TSRA. AFTERNOON
  LAKE BREEZES.
* SUNDAY AND MONDAY...DRY/VFR.
* TUESDAY...CHANCE OF TSRA.

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 310147
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
847 PM CDT WED JUL 30 2014

.DISCUSSION...
844 PM CDT

TEMPERATURES CONTINUE TO HOLD-UP AROUND 70 FOR MOST OF THE AREA.
THE EXCEPTION IS LOCATIONS ADJACENT TO LAKE MICHIGAN WHERE THE
COOLER MARINE ENVIRONMENT HAS BEEN ABLE TO KEEP TEMPS IN THE MID
60S THIS EVENING WITH A CONTINUED ONSHORE FLOW. EXPECT WINDS TO
TURN AROUND FROM THE SOUTH OVERNIGHT. THIS WILL LIKELY KEEP THE
URBAN AREAS A LITTLE WARMER. ELSEWEHERE TEMPS SHUD CONTINUE TO
SLOWLY COOL INTO THE MID/UPR 50S.

BEACHLER

&&

.PREV DISCUSSION...
254 PM CDT

A HIGH AMPLITUDE LONGWAVE PATTERN THAT HAS BEEN IN PLACE FOR THE
PAST FEW DAYS WILL PERSIST FOR THE NEXT FEW DAYS WITH DEEP LONG WAVE
TROUGHING OVER THE ERN CONUS AND AN UPPER LOW CENTER OVER JAMES
BAY...WITH RIDGING OVER THE WRN CONUS.  THE LOCAL AREA WILL REMAIN
UNDER GENERALLY NWLY FLOW ALOFT UNDER THE SWRN PERIPHERY OF THE
UPPER LOW.  THIS WILL ALLOW FOR A SERIES OF WEAK SHORT WAVES TO
RIPPLE THROUGH THE NWLY FLOW ALOFT OVER THE LOCAL AREA.

FOR THE REMAINDER OF THIS AFTERNOON AND THIS EVENING...THE MAIN
CONCERN WILL BE THE LAKE BREEZE BOUNDARY QUICKLY PUSHING INLAND
THROUGH NERN IL AND NWRN IN.  TEMPERATURES WILL DROP OFF SEVERAL
DEGREES WITH THE PASSAGE OF THE BOUNDARY AND LAKEFRONT LOCATIONS
HAVE ALREADY DROPPED INTO THE MIDDLE 60S.  THE ENVIRONMENT AHEAD OF
THE BOUNDARY IS MODESTLY MOIST AND UNSTABLE.  WITH CYCLONIC FLOW
ALOFT...DIURNAL CU HAS BEEN DEVELOPING OVER THE REGION PER THE LATEST
SATELLITE IMAGERY.  AS OF EARLY THIS AFTERNOON...HAVE NOT SEEN ANY
SHRA/TSRA ACTIVITY OVER NRN IL/NWRN IN...BUT THE REGION REMAINS
MODESTLY UNSTABLE WITH DEWPOINTS IN THE MIDDLE TO UPPER 50S.  THERE
WILL STILL BE A CHANCE FOR SOME SHRA/TSRA FOCUSED ALONG THE LAKE
BREEZE BOUNDARY AS WELL AS SOME ISOLD SHRA OR AN EVEN MORE ISOLD TS
OVER THE AREA THROUGH SUNSET.  DURG THE EVENING AND INTO THE
OVERNIGHT HOURS...ANY DIURNAL PCPN WILL DISSIPATE AND AND RESIDUAL
PCPN WILL BE WELL NORTH OF THE AREA INVOF ON OF THE SEEMINGLY
ENDLESS SERIES OF IMPULSES DROPPING THROUGH THE NORTHWEST FLOW.

LITTLE CHANGE IS EXPECTED FOR TOMORROW THROUGH SATURDAY AS THE
SYNOPTIC SCALE PATTERN SHOULD CHANGE LITTLE AND A WEAK GRADIENT
PATTERN WILL PERSIST AT THE SFC.  UNDER PERSISTENT NWLY FLOW
ALOFT...THE SERIES OF WEAK SHORTWAVES WILL CONTINUE TO BRING
PERIODIC CHANCES FOR SCT SHRA AND ISOLD TSRA...WITH THE BETTER
CHANCES FOR TS DURG THE AFTERNOON HOURS.  THE WEAK GRADIENT PATTERN
AT THE SFC SHOULD ALLOW FOR DAILY LAKE BREEZE DEVELOPMENT...WITH THE
MAIN QUESTION BEING HOW FAR INLAND A LAKE BREEZE WILL PENETRATE.
CERTAINLY...IT IS LIKELY THAT LAKEFRONT LOCATIONS WILL TURN COOLER
IN THE AFTERNOON...BUT IT IS LESS CERTAIN HOW FAR INLAND THE LAKE
COOLING WILL PENETRATE.  SO...WILL KEEP THE MAX TEMP FORECAST A BIT
ON THE CONSERVATIVE SIDE AS FAR AS LAKE INFLUENCE IS CONCERNED AND
LIMIT THE COOLING TO THE IMMEDIATE LAKEFRONT AND ALLOW MAX TEMPS TO
BE MORE REPRESENTATIVE OF THE LARGE SCALE PATTERN.  UNDER THE COOL
NWLY FLOW ALOFT...HIGHS WILL REMAIN A FEW DEGREES BELOW NORMAL INTO
THE WEEKEND WITH HIGHS AROUND 80F OR SO.  TIMING OF PERIODS OF PCPN
WILL BE LESS CERTAIN THAN THE TEMPERATURE TRENDS FOR THE NEXT FEW
DAYS AND WILL GENERALLY BE DEPENDENT ON THE TIMING OF SHORTWAVE
ENERGY DROPPING THROUGH THE NWLY FLOW ALOFT.  SO...WHILE NO DAY IN
THE SHORT TERM FORECAST PERIOD WILL BE A TOTAL WASHOUT...THERE
SHOULD BE PERIODS OF SCT SHRA AND ISOLD TSRA.

THE LONGER RANGE GUIDANCE IS IN GENERALLY GOOD AGREEMENT ON THE
UPPER LEVEL PATTERN BECOMING MORE PROGRESSIVE THROUGH THE WEEKEND.
THIS WILL INITIATE A WARMING TREND AS THE UPPER LEVEL RIDGING MOVES
OUT OVER THE WESTERN PLAINS ON SUNDAY WHILE THE UPPER LOW OVER JAMES
BAY KICKS OUT TO THE NORTHEAST...LEAVING WEAKER LONGWAVE TROUGHING
OVER THE ERN CONUS.  SUNDAY SHOULD BE A TRANSITIONAL DAY...WITH
INLAND TEMPS A LITTLE HIGHER...BUT A WEAK GRADIENT PERSISTING AT THE
SURFACE WILL ALLOW FOR ANOTHER LAKE BREEZE DAY AND COOLER CONDITIONS
NEAR THE LAKE. RISING HEIGHTS OVER THE MIDWEST SHOULD ALLOW FOR MAX
TEMPS TO CLIMB INTO THE MIDDLE 80S BY MONDAY.

MORE UNCERTAINTY WILL CREEP INTO THE FORECAST DURING THE EXTENDED
FORECAST PERIOD AS FLOW BECOMES MORE ZONAL OVER THE MIDWEST.  IN THE
INCREASINGLY ZONAL FLOW...SHORT WAVE STRENGTH AND TIMING WILL BECOME
MORE UNCERTAIN...SO...CONFIDENCE IN THE SENSIBLE WEATHER FORECAST
WILL INCREASE WITH TIME THROUGH THE EXTENDED FORECAST PERIOD.
HOWEVER...THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THE WARMING
TREND COULD BE BRIEF AS A WEAK UPPER LOW HANGS BACK OVER THE LOWER
MISSISSIPPI VALLEY THROUGH THE PERIOD AND THE UPPER RIDGING WILL NOT
BUILD ANY FARTHER EAST THAN THE CENTRAL PLAINS.  ALSO...THE SFC
PATTERN SHOULD REMAIN WEAK...SO DAILY LAKE BREEZE DEVELOPMENT WILL
BE LIKELY AS WELL. THE TREND FOR THE EXTEDNED FORECAST PERIOD IS
SHAPPING UP FOR MORE BELOW NORMAL TEMPERATURES WITH PERIODIC CHANCES
FOR AT LEAST SOME LIGHT PCPN.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* ISOLATED SHRA/TSRA THURSDAY AFTERNOON. CMS

//DISCUSSION...UPDATED 00Z...

A LAKE BREEZE HAS MOVED WELL WEST OF ORD/MDW LATE THIS AFTERNOON
AND WILL CONTINUE WEST UNTIL IT DISSIPATES THIS EVENING. THE
GRADIENT WILL BE QUITE WEAK TONIGHT AND WINDS WILL EVENTUALLY
BECOME LIGHT AND VARIABLE AND LIKELY CALM IN MANY LOCATIONS. WINDS
WILL BECOME LIGHT WEST/SOUTHWEST AFTER SUNRISE AND REMAIN WESTERLY
THURSDAY WITH SPEEDS INCREASING TO 10-12KTS WITH A FEW HIGHER
GUSTS POSSIBLE IN THE AFTERNOON. WIND SPEEDS APPEAR STRONG ENOUGH
TO PREVENT A LAKE BREEZE FROM REACHING ORD/MDW...BUT A LAKE BREEZE
MAY STILL FORM NEAR THE LAKE.

CU FIELD IS QUICKLY DISSIPATING THIS EVENING AND NOT EXPECTING ANY
ADDITIONAL SHOWERS. SHOWERS AND THUNDERSTORMS OVER NORTHERN WI
WILL MOVE SOUTH THIS EVENING BUT ARE EXPECTED TO DISSIPATE BEFORE
REACHING NORTHERN IL WITH JUST FEW/SCT MID CLOUDS OVERNIGHT.
ISOLATED SHOWERS/THUNDERSTORMS ARE POSSIBLE THURSDAY AFTERNOON
INTO EARLY EVENING.

WITH THE LIGHT WINDS...TEMPS WILL LIKELY COOL TOWARD THE DEWPOINTS
OVERNIGHT AND TOWARD MORNING WITH SOME LIGHT/SHALLOW GROUND FOG
POSSIBLE IN THE USUAL SPOTS AND ADDED FOG MENTION TO DPA. CMS

//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* LOW FOR ISOLATED SHRA/TSRA THURSDAY AFTERNOON. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY AND SATURDAY...AFTERNOON ISOLATED SHRA/TSRA. AFTERNOON
  LAKE BREEZES.
* SUNDAY AND MONDAY...DRY/VFR.
* TUESDAY...CHANCE OF TSRA.

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 310147
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
847 PM CDT WED JUL 30 2014

.DISCUSSION...
844 PM CDT

TEMPERATURES CONTINUE TO HOLD-UP AROUND 70 FOR MOST OF THE AREA.
THE EXCEPTION IS LOCATIONS ADJACENT TO LAKE MICHIGAN WHERE THE
COOLER MARINE ENVIRONMENT HAS BEEN ABLE TO KEEP TEMPS IN THE MID
60S THIS EVENING WITH A CONTINUED ONSHORE FLOW. EXPECT WINDS TO
TURN AROUND FROM THE SOUTH OVERNIGHT. THIS WILL LIKELY KEEP THE
URBAN AREAS A LITTLE WARMER. ELSEWEHERE TEMPS SHUD CONTINUE TO
SLOWLY COOL INTO THE MID/UPR 50S.

BEACHLER

&&

.PREV DISCUSSION...
254 PM CDT

A HIGH AMPLITUDE LONGWAVE PATTERN THAT HAS BEEN IN PLACE FOR THE
PAST FEW DAYS WILL PERSIST FOR THE NEXT FEW DAYS WITH DEEP LONG WAVE
TROUGHING OVER THE ERN CONUS AND AN UPPER LOW CENTER OVER JAMES
BAY...WITH RIDGING OVER THE WRN CONUS.  THE LOCAL AREA WILL REMAIN
UNDER GENERALLY NWLY FLOW ALOFT UNDER THE SWRN PERIPHERY OF THE
UPPER LOW.  THIS WILL ALLOW FOR A SERIES OF WEAK SHORT WAVES TO
RIPPLE THROUGH THE NWLY FLOW ALOFT OVER THE LOCAL AREA.

FOR THE REMAINDER OF THIS AFTERNOON AND THIS EVENING...THE MAIN
CONCERN WILL BE THE LAKE BREEZE BOUNDARY QUICKLY PUSHING INLAND
THROUGH NERN IL AND NWRN IN.  TEMPERATURES WILL DROP OFF SEVERAL
DEGREES WITH THE PASSAGE OF THE BOUNDARY AND LAKEFRONT LOCATIONS
HAVE ALREADY DROPPED INTO THE MIDDLE 60S.  THE ENVIRONMENT AHEAD OF
THE BOUNDARY IS MODESTLY MOIST AND UNSTABLE.  WITH CYCLONIC FLOW
ALOFT...DIURNAL CU HAS BEEN DEVELOPING OVER THE REGION PER THE LATEST
SATELLITE IMAGERY.  AS OF EARLY THIS AFTERNOON...HAVE NOT SEEN ANY
SHRA/TSRA ACTIVITY OVER NRN IL/NWRN IN...BUT THE REGION REMAINS
MODESTLY UNSTABLE WITH DEWPOINTS IN THE MIDDLE TO UPPER 50S.  THERE
WILL STILL BE A CHANCE FOR SOME SHRA/TSRA FOCUSED ALONG THE LAKE
BREEZE BOUNDARY AS WELL AS SOME ISOLD SHRA OR AN EVEN MORE ISOLD TS
OVER THE AREA THROUGH SUNSET.  DURG THE EVENING AND INTO THE
OVERNIGHT HOURS...ANY DIURNAL PCPN WILL DISSIPATE AND AND RESIDUAL
PCPN WILL BE WELL NORTH OF THE AREA INVOF ON OF THE SEEMINGLY
ENDLESS SERIES OF IMPULSES DROPPING THROUGH THE NORTHWEST FLOW.

LITTLE CHANGE IS EXPECTED FOR TOMORROW THROUGH SATURDAY AS THE
SYNOPTIC SCALE PATTERN SHOULD CHANGE LITTLE AND A WEAK GRADIENT
PATTERN WILL PERSIST AT THE SFC.  UNDER PERSISTENT NWLY FLOW
ALOFT...THE SERIES OF WEAK SHORTWAVES WILL CONTINUE TO BRING
PERIODIC CHANCES FOR SCT SHRA AND ISOLD TSRA...WITH THE BETTER
CHANCES FOR TS DURG THE AFTERNOON HOURS.  THE WEAK GRADIENT PATTERN
AT THE SFC SHOULD ALLOW FOR DAILY LAKE BREEZE DEVELOPMENT...WITH THE
MAIN QUESTION BEING HOW FAR INLAND A LAKE BREEZE WILL PENETRATE.
CERTAINLY...IT IS LIKELY THAT LAKEFRONT LOCATIONS WILL TURN COOLER
IN THE AFTERNOON...BUT IT IS LESS CERTAIN HOW FAR INLAND THE LAKE
COOLING WILL PENETRATE.  SO...WILL KEEP THE MAX TEMP FORECAST A BIT
ON THE CONSERVATIVE SIDE AS FAR AS LAKE INFLUENCE IS CONCERNED AND
LIMIT THE COOLING TO THE IMMEDIATE LAKEFRONT AND ALLOW MAX TEMPS TO
BE MORE REPRESENTATIVE OF THE LARGE SCALE PATTERN.  UNDER THE COOL
NWLY FLOW ALOFT...HIGHS WILL REMAIN A FEW DEGREES BELOW NORMAL INTO
THE WEEKEND WITH HIGHS AROUND 80F OR SO.  TIMING OF PERIODS OF PCPN
WILL BE LESS CERTAIN THAN THE TEMPERATURE TRENDS FOR THE NEXT FEW
DAYS AND WILL GENERALLY BE DEPENDENT ON THE TIMING OF SHORTWAVE
ENERGY DROPPING THROUGH THE NWLY FLOW ALOFT.  SO...WHILE NO DAY IN
THE SHORT TERM FORECAST PERIOD WILL BE A TOTAL WASHOUT...THERE
SHOULD BE PERIODS OF SCT SHRA AND ISOLD TSRA.

THE LONGER RANGE GUIDANCE IS IN GENERALLY GOOD AGREEMENT ON THE
UPPER LEVEL PATTERN BECOMING MORE PROGRESSIVE THROUGH THE WEEKEND.
THIS WILL INITIATE A WARMING TREND AS THE UPPER LEVEL RIDGING MOVES
OUT OVER THE WESTERN PLAINS ON SUNDAY WHILE THE UPPER LOW OVER JAMES
BAY KICKS OUT TO THE NORTHEAST...LEAVING WEAKER LONGWAVE TROUGHING
OVER THE ERN CONUS.  SUNDAY SHOULD BE A TRANSITIONAL DAY...WITH
INLAND TEMPS A LITTLE HIGHER...BUT A WEAK GRADIENT PERSISTING AT THE
SURFACE WILL ALLOW FOR ANOTHER LAKE BREEZE DAY AND COOLER CONDITIONS
NEAR THE LAKE. RISING HEIGHTS OVER THE MIDWEST SHOULD ALLOW FOR MAX
TEMPS TO CLIMB INTO THE MIDDLE 80S BY MONDAY.

MORE UNCERTAINTY WILL CREEP INTO THE FORECAST DURING THE EXTENDED
FORECAST PERIOD AS FLOW BECOMES MORE ZONAL OVER THE MIDWEST.  IN THE
INCREASINGLY ZONAL FLOW...SHORT WAVE STRENGTH AND TIMING WILL BECOME
MORE UNCERTAIN...SO...CONFIDENCE IN THE SENSIBLE WEATHER FORECAST
WILL INCREASE WITH TIME THROUGH THE EXTENDED FORECAST PERIOD.
HOWEVER...THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THE WARMING
TREND COULD BE BRIEF AS A WEAK UPPER LOW HANGS BACK OVER THE LOWER
MISSISSIPPI VALLEY THROUGH THE PERIOD AND THE UPPER RIDGING WILL NOT
BUILD ANY FARTHER EAST THAN THE CENTRAL PLAINS.  ALSO...THE SFC
PATTERN SHOULD REMAIN WEAK...SO DAILY LAKE BREEZE DEVELOPMENT WILL
BE LIKELY AS WELL. THE TREND FOR THE EXTEDNED FORECAST PERIOD IS
SHAPPING UP FOR MORE BELOW NORMAL TEMPERATURES WITH PERIODIC CHANCES
FOR AT LEAST SOME LIGHT PCPN.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* ISOLATED SHRA/TSRA THURSDAY AFTERNOON. CMS

//DISCUSSION...UPDATED 00Z...

A LAKE BREEZE HAS MOVED WELL WEST OF ORD/MDW LATE THIS AFTERNOON
AND WILL CONTINUE WEST UNTIL IT DISSIPATES THIS EVENING. THE
GRADIENT WILL BE QUITE WEAK TONIGHT AND WINDS WILL EVENTUALLY
BECOME LIGHT AND VARIABLE AND LIKELY CALM IN MANY LOCATIONS. WINDS
WILL BECOME LIGHT WEST/SOUTHWEST AFTER SUNRISE AND REMAIN WESTERLY
THURSDAY WITH SPEEDS INCREASING TO 10-12KTS WITH A FEW HIGHER
GUSTS POSSIBLE IN THE AFTERNOON. WIND SPEEDS APPEAR STRONG ENOUGH
TO PREVENT A LAKE BREEZE FROM REACHING ORD/MDW...BUT A LAKE BREEZE
MAY STILL FORM NEAR THE LAKE.

CU FIELD IS QUICKLY DISSIPATING THIS EVENING AND NOT EXPECTING ANY
ADDITIONAL SHOWERS. SHOWERS AND THUNDERSTORMS OVER NORTHERN WI
WILL MOVE SOUTH THIS EVENING BUT ARE EXPECTED TO DISSIPATE BEFORE
REACHING NORTHERN IL WITH JUST FEW/SCT MID CLOUDS OVERNIGHT.
ISOLATED SHOWERS/THUNDERSTORMS ARE POSSIBLE THURSDAY AFTERNOON
INTO EARLY EVENING.

WITH THE LIGHT WINDS...TEMPS WILL LIKELY COOL TOWARD THE DEWPOINTS
OVERNIGHT AND TOWARD MORNING WITH SOME LIGHT/SHALLOW GROUND FOG
POSSIBLE IN THE USUAL SPOTS AND ADDED FOG MENTION TO DPA. CMS

//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* LOW FOR ISOLATED SHRA/TSRA THURSDAY AFTERNOON. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY AND SATURDAY...AFTERNOON ISOLATED SHRA/TSRA. AFTERNOON
  LAKE BREEZES.
* SUNDAY AND MONDAY...DRY/VFR.
* TUESDAY...CHANCE OF TSRA.

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KILX 310032
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
732 PM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 730 PM CDT Wed Jul 30 2014

Diurnal clouds quickly fading, leading behind some cirrus left
over from convection in the central Plains, as well as a smoke
layer coming in from the northwest. Have updated the sky grids to
lower the cloud cover, primarily over the next 6 hours or so. This
did not impact the zone forecasts, although an update was sent to
that product to remove the late afternoon period. Temperatures
appear on track and no adjustments needed.

Geelhart

&&

.AVIATION...
ISSUED 610 PM CDT Wed Jul 30 2014

Little change needed to the going TAF set. Diurnal cumulus is
quickly fading, and any lingering clouds around 6000 feet will be
going away over the next hour or two. Scattered clouds expected to
redevelop again toward 15Z or so. Cannot rule out a stray
afternoon shower from KPIA-KCMI, but chances are too low to
include a mention.

Geelhart

&&

.PREV DISCUSSION...
ISSUED 300 PM CDT Wed Jul 30 2014

An upper level trough across the eastern half of the CONUS will
continue to keep Illinois in an unseasonably cool air mass into the
weekend. Chances of spotty showers or storms will continue through
Saturday, then a dry period may develop as into early next week as
upper level ridging advances into IL. Warmer conditions appear in
the far extended as high temps approach normal on Tue and Wed.

SHORT TERM...Tonight through Saturday.

A few showers bubbled up this afternoon northeast of a line from
Bloomington to Mattoon. Any lightning through 230 pm remained in
Indiana closer to the better mid-level instability. RAP sounding
analysis east of Champaign showed only 150-200 J/kg MLCAPE for
storm updraft development in our counties, which supports the
limited vertical development observed visually and on satellite.
We expect any showers in our northeastern forecast area to
dissipate by 00z/7pm, so no precip was included in the evening
grids. The diurnally driven cumulus will dissipate with the
passage of sunset as well, providing clear skies overnight.
Surface winds will become light and variable tonight, creating
favorable radiational cooling conditions. Lows should dip into the
mid to upper 50s in most locations. A few spots could linger in
the low 60s depending on localized surface dew point trends.

Thursday will be a repeat of Wednesday with a few isolated
afternoon showers east-northeast of PIA to BMI to MTO. Highs
will top out in the low 80s with relatively comfortable dew points
around 60F.

Friday and Saturday will feature the passage of stronger 500mb
shortwaves, increasing the potential and coverage of showers and
storms. We still expect mainly 30-40% coverage on both days, but
thunder potential will be higher due to deeper mid-level
instability and increasing moisture. Highs will still remain below
normal in the low 80s through Saturday.

LONG TERM...Sunday through Wednesday.

The upper level low will shift east of Illinois for Sunday through
Monday with upper level ridging providing dry conditions both days.
Slow warming will begin...with highs by Monday approaching the
middle 80s. Storm chances are expected to return on Tuesday and
Wednesday the next series of shortwaves roll over the top of the
ridge in the Plains. No strong to severe weather is anticipated at
this point. A warm front developing north of IL will help
southerly flow bring mid to upper 80s into our forecast area,
which are closer to normal for early Aug.

Shimon

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$







000
FXUS63 KILX 310032
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
732 PM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 730 PM CDT Wed Jul 30 2014

Diurnal clouds quickly fading, leading behind some cirrus left
over from convection in the central Plains, as well as a smoke
layer coming in from the northwest. Have updated the sky grids to
lower the cloud cover, primarily over the next 6 hours or so. This
did not impact the zone forecasts, although an update was sent to
that product to remove the late afternoon period. Temperatures
appear on track and no adjustments needed.

Geelhart

&&

.AVIATION...
ISSUED 610 PM CDT Wed Jul 30 2014

Little change needed to the going TAF set. Diurnal cumulus is
quickly fading, and any lingering clouds around 6000 feet will be
going away over the next hour or two. Scattered clouds expected to
redevelop again toward 15Z or so. Cannot rule out a stray
afternoon shower from KPIA-KCMI, but chances are too low to
include a mention.

Geelhart

&&

.PREV DISCUSSION...
ISSUED 300 PM CDT Wed Jul 30 2014

An upper level trough across the eastern half of the CONUS will
continue to keep Illinois in an unseasonably cool air mass into the
weekend. Chances of spotty showers or storms will continue through
Saturday, then a dry period may develop as into early next week as
upper level ridging advances into IL. Warmer conditions appear in
the far extended as high temps approach normal on Tue and Wed.

SHORT TERM...Tonight through Saturday.

A few showers bubbled up this afternoon northeast of a line from
Bloomington to Mattoon. Any lightning through 230 pm remained in
Indiana closer to the better mid-level instability. RAP sounding
analysis east of Champaign showed only 150-200 J/kg MLCAPE for
storm updraft development in our counties, which supports the
limited vertical development observed visually and on satellite.
We expect any showers in our northeastern forecast area to
dissipate by 00z/7pm, so no precip was included in the evening
grids. The diurnally driven cumulus will dissipate with the
passage of sunset as well, providing clear skies overnight.
Surface winds will become light and variable tonight, creating
favorable radiational cooling conditions. Lows should dip into the
mid to upper 50s in most locations. A few spots could linger in
the low 60s depending on localized surface dew point trends.

Thursday will be a repeat of Wednesday with a few isolated
afternoon showers east-northeast of PIA to BMI to MTO. Highs
will top out in the low 80s with relatively comfortable dew points
around 60F.

Friday and Saturday will feature the passage of stronger 500mb
shortwaves, increasing the potential and coverage of showers and
storms. We still expect mainly 30-40% coverage on both days, but
thunder potential will be higher due to deeper mid-level
instability and increasing moisture. Highs will still remain below
normal in the low 80s through Saturday.

LONG TERM...Sunday through Wednesday.

The upper level low will shift east of Illinois for Sunday through
Monday with upper level ridging providing dry conditions both days.
Slow warming will begin...with highs by Monday approaching the
middle 80s. Storm chances are expected to return on Tuesday and
Wednesday the next series of shortwaves roll over the top of the
ridge in the Plains. No strong to severe weather is anticipated at
this point. A warm front developing north of IL will help
southerly flow bring mid to upper 80s into our forecast area,
which are closer to normal for early Aug.

Shimon

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 302331
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
631 PM CDT WED JUL 30 2014

.DISCUSSION...
254 PM CDT

A HIGH AMPLITUDE LONGWAVE PATTERN THAT HAS BEEN IN PLACE FOR THE
PAST FEW DAYS WILL PERSIST FOR THE NEXT FEW DAYS WITH DEEP LONG WAVE
TROUGHING OVER THE ERN CONUS AND AN UPPER LOW CENTER OVER JAMES
BAY...WITH RIDGING OVER THE WRN CONUS.  THE LOCAL AREA WILL REMAIN
UNDER GENERALLY NWLY FLOW ALOFT UNDER THE SWRN PERIPHERY OF THE
UPPER LOW.  THIS WILL ALLOW FOR A SERIES OF WEAK SHORT WAVES TO
RIPPLE THROUGH THE NWLY FLOW ALOFT OVER THE LOCAL AREA.

FOR THE REMAINDER OF THIS AFTERNOON AND THIS EVENING...THE MAIN
CONCERN WILL BE THE LAKE BREEZE BOUNDARY QUICKLY PUSHING INLAND
THROUGH NERN IL AND NWRN IN.  TEMPERATURES WILL DROP OFF SEVERAL
DEGREES WITH THE PASSAGE OF THE BOUNDARY AND LAKEFRONT LOCATIONS
HAVE ALREADY DROPPED INTO THE MIDDLE 60S.  THE ENVIRONMENT AHEAD OF
THE BOUNDARY IS MODESTLY MOIST AND UNSTABLE.  WITH CYCLONIC FLOW
ALOFT...DIURNAL CU HAS BEEN DEVELOPING OVER THE REGION PER THE LATEST
SATELLITE IMAGERY.  AS OF EARLY THIS AFTERNOON...HAVE NOT SEEN ANY
SHRA/TSRA ACTIVITY OVER NRN IL/NWRN IN...BUT THE REGION REMAINS
MODESTLY UNSTABLE WITH DEWPOINTS IN THE MIDDLE TO UPPER 50S.  THERE
WILL STILL BE A CHANCE FOR SOME SHRA/TSRA FOCUSED ALONG THE LAKE
BREEZE BOUNDARY AS WELL AS SOME ISOLD SHRA OR AN EVEN MORE ISOLD TS
OVER THE AREA THROUGH SUNSET.  DURG THE EVENING AND INTO THE
OVERNIGHT HOURS...ANY DIURNAL PCPN WILL DISSIPATE AND AND RESIDUAL
PCPN WILL BE WELL NORTH OF THE AREA INVOF ON OF THE SEEMINGLY
ENDLESS SERIES OF IMPULSES DROPPING THROUGH THE NORTHWEST FLOW.

LITTLE CHANGE IS EXPECTED FOR TOMORROW THROUGH SATURDAY AS THE
SYNOPTIC SCALE PATTERN SHOULD CHANGE LITTLE AND A WEAK GRADIENT
PATTERN WILL PERSIST AT THE SFC.  UNDER PERSISTENT NWLY FLOW
ALOFT...THE SERIES OF WEAK SHORTWAVES WILL CONTINUE TO BRING
PERIODIC CHANCES FOR SCT SHRA AND ISOLD TSRA...WITH THE BETTER
CHANCES FOR TS DURG THE AFTERNOON HOURS.  THE WEAK GRADIENT PATTERN
AT THE SFC SHOULD ALLOW FOR DAILY LAKE BREEZE DEVELOPMENT...WITH THE
MAIN QUESTION BEING HOW FAR INLAND A LAKE BREEZE WILL PENETRATE.
CERTAINLY...IT IS LIKELY THAT LAKEFRONT LOCATIONS WILL TURN COOLER
IN THE AFTERNOON...BUT IT IS LESS CERTAIN HOW FAR INLAND THE LAKE
COOLING WILL PENETRATE.  SO...WILL KEEP THE MAX TEMP FORECAST A BIT
ON THE CONSERVATIVE SIDE AS FAR AS LAKE INFLUENCE IS CONCERNED AND
LIMIT THE COOLING TO THE IMMEDIATE LAKEFRONT AND ALLOW MAX TEMPS TO
BE MORE REPRESENTATIVE OF THE LARGE SCALE PATTERN.  UNDER THE COOL
NWLY FLOW ALOFT...HIGHS WILL REMAIN A FEW DEGREES BELOW NORMAL INTO
THE WEEKEND WITH HIGHS AROUND 80F OR SO.  TIMING OF PERIODS OF PCPN
WILL BE LESS CERTAIN THAN THE TEMPERATURE TRENDS FOR THE NEXT FEW
DAYS AND WILL GENERALLY BE DEPENDENT ON THE TIMING OF SHORTWAVE
ENERGY DROPPING THROUGH THE NWLY FLOW ALOFT.  SO...WHILE NO DAY IN
THE SHORT TERM FORECAST PERIOD WILL BE A TOTAL WASHOUT...THERE
SHOULD BE PERIODS OF SCT SHRA AND ISOLD TSRA.

THE LONGER RANGE GUIDANCE IS IN GENERALLY GOOD AGREEMENT ON THE
UPPER LEVEL PATTERN BECOMING MORE PROGRESSIVE THROUGH THE WEEKEND.
THIS WILL INITIATE A WARMING TREND AS THE UPPER LEVEL RIDGING MOVES
OUT OVER THE WESTERN PLAINS ON SUNDAY WHILE THE UPPER LOW OVER JAMES
BAY KICKS OUT TO THE NORTHEAST...LEAVING WEAKER LONGWAVE TROUGHING
OVER THE ERN CONUS.  SUNDAY SHOULD BE A TRANSITIONAL DAY...WITH
INLAND TEMPS A LITTLE HIGHER...BUT A WEAK GRADIENT PERSISTING AT THE
SURFACE WILL ALLOW FOR ANOTHER LAKE BREEZE DAY AND COOLER CONDITIONS
NEAR THE LAKE. RISING HEIGHTS OVER THE MIDWEST SHOULD ALLOW FOR MAX
TEMPS TO CLIMB INTO THE MIDDLE 80S BY MONDAY.

MORE UNCERTAINTY WILL CREEP INTO THE FORECAST DURING THE EXTENDED
FORECAST PERIOD AS FLOW BECOMES MORE ZONAL OVER THE MIDWEST.  IN THE
INCREASINGLY ZONAL FLOW...SHORT WAVE STRENGTH AND TIMING WILL BECOME
MORE UNCERTAIN...SO...CONFIDENCE IN THE SENSIBLE WEATHER FORECAST
WILL INCREASE WITH TIME THROUGH THE EXTENDED FORECAST PERIOD.
HOWEVER...THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THE WARMING
TREND COULD BE BRIEF AS A WEAK UPPER LOW HANGS BACK OVER THE LOWER
MISSISSIPPI VALLEY THROUGH THE PERIOD AND THE UPPER RIDGING WILL NOT
BUILD ANY FARTHER EAST THAN THE CENTRAL PLAINS.  ALSO...THE SFC
PATTERN SHOULD REMAIN WEAK...SO DAILY LAKE BREEZE DEVELOPMENT WILL
BE LIKELY AS WELL. THE TREND FOR THE EXTEDNED FORECAST PERIOD IS
SHAPPING UP FOR MORE BELOW NORMAL TEMPERATURES WITH PERIODIC CHANCES
FOR AT LEAST SOME LIGHT PCPN.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* ISOLATED SHRA/TSRA THURSDAY AFTERNOON. CMS

//DISCUSSION...UPDATED 00Z...

A LAKE BREEZE HAS MOVED WELL WEST OF ORD/MDW LATE THIS AFTERNOON
AND WILL CONTINUE WEST UNTIL IT DISSIPATES THIS EVENING. THE
GRADIENT WILL BE QUITE WEAK TONIGHT AND WINDS WILL EVENTUALLY
BECOME LIGHT AND VARIABLE AND LIKELY CALM IN MANY LOCATIONS. WINDS
WILL BECOME LIGHT WEST/SOUTHWEST AFTER SUNRISE AND REMAIN WESTERLY
THURSDAY WITH SPEEDS INCREASING TO 10-12KTS WITH A FEW HIGHER
GUSTS POSSIBLE IN THE AFTERNOON. WIND SPEEDS APPEAR STRONG ENOUGH
TO PREVENT A LAKE BREEZE FROM REACHING ORD/MDW...BUT A LAKE BREEZE
MAY STILL FORM NEAR THE LAKE.

CU FIELD IS QUICKLY DISSIPATING THIS EVENING AND NOT EXPECTING ANY
ADDITIONAL SHOWERS. SHOWERS AND THUNDERSTORMS OVER NORTHERN WI
WILL MOVE SOUTH THIS EVENING BUT ARE EXPECTED TO DISSIPATE BEFORE
REACHING NORTHERN IL WITH JUST FEW/SCT MID CLOUDS OVERNIGHT.
ISOLATED SHOWERS/THUNDERSTORMS ARE POSSIBLE THURSDAY AFTERNOON
INTO EARLY EVENING.

WITH THE LIGHT WINDS...TEMPS WILL LIKELY COOL TOWARD THE DEWPOINTS
OVERNIGHT AND TOWARD MORNING WITH SOME LIGHT/SHALLOW GROUND FOG
POSSIBLE IN THE USUAL SPOTS AND ADDED FOG MENTION TO DPA. CMS

//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* LOW FOR ISOLATED SHRA/TSRA THURSDAY AFTERNOON. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY AND SATURDAY...AFTERNOON ISOLATED SHRA/TSRA. AFTERNOON
  LAKE BREEZES.
* SUNDAY AND MONDAY...DRY/VFR.
* TUESDAY...CHANCE OF TSRA.

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 302331
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
631 PM CDT WED JUL 30 2014

.DISCUSSION...
254 PM CDT

A HIGH AMPLITUDE LONGWAVE PATTERN THAT HAS BEEN IN PLACE FOR THE
PAST FEW DAYS WILL PERSIST FOR THE NEXT FEW DAYS WITH DEEP LONG WAVE
TROUGHING OVER THE ERN CONUS AND AN UPPER LOW CENTER OVER JAMES
BAY...WITH RIDGING OVER THE WRN CONUS.  THE LOCAL AREA WILL REMAIN
UNDER GENERALLY NWLY FLOW ALOFT UNDER THE SWRN PERIPHERY OF THE
UPPER LOW.  THIS WILL ALLOW FOR A SERIES OF WEAK SHORT WAVES TO
RIPPLE THROUGH THE NWLY FLOW ALOFT OVER THE LOCAL AREA.

FOR THE REMAINDER OF THIS AFTERNOON AND THIS EVENING...THE MAIN
CONCERN WILL BE THE LAKE BREEZE BOUNDARY QUICKLY PUSHING INLAND
THROUGH NERN IL AND NWRN IN.  TEMPERATURES WILL DROP OFF SEVERAL
DEGREES WITH THE PASSAGE OF THE BOUNDARY AND LAKEFRONT LOCATIONS
HAVE ALREADY DROPPED INTO THE MIDDLE 60S.  THE ENVIRONMENT AHEAD OF
THE BOUNDARY IS MODESTLY MOIST AND UNSTABLE.  WITH CYCLONIC FLOW
ALOFT...DIURNAL CU HAS BEEN DEVELOPING OVER THE REGION PER THE LATEST
SATELLITE IMAGERY.  AS OF EARLY THIS AFTERNOON...HAVE NOT SEEN ANY
SHRA/TSRA ACTIVITY OVER NRN IL/NWRN IN...BUT THE REGION REMAINS
MODESTLY UNSTABLE WITH DEWPOINTS IN THE MIDDLE TO UPPER 50S.  THERE
WILL STILL BE A CHANCE FOR SOME SHRA/TSRA FOCUSED ALONG THE LAKE
BREEZE BOUNDARY AS WELL AS SOME ISOLD SHRA OR AN EVEN MORE ISOLD TS
OVER THE AREA THROUGH SUNSET.  DURG THE EVENING AND INTO THE
OVERNIGHT HOURS...ANY DIURNAL PCPN WILL DISSIPATE AND AND RESIDUAL
PCPN WILL BE WELL NORTH OF THE AREA INVOF ON OF THE SEEMINGLY
ENDLESS SERIES OF IMPULSES DROPPING THROUGH THE NORTHWEST FLOW.

LITTLE CHANGE IS EXPECTED FOR TOMORROW THROUGH SATURDAY AS THE
SYNOPTIC SCALE PATTERN SHOULD CHANGE LITTLE AND A WEAK GRADIENT
PATTERN WILL PERSIST AT THE SFC.  UNDER PERSISTENT NWLY FLOW
ALOFT...THE SERIES OF WEAK SHORTWAVES WILL CONTINUE TO BRING
PERIODIC CHANCES FOR SCT SHRA AND ISOLD TSRA...WITH THE BETTER
CHANCES FOR TS DURG THE AFTERNOON HOURS.  THE WEAK GRADIENT PATTERN
AT THE SFC SHOULD ALLOW FOR DAILY LAKE BREEZE DEVELOPMENT...WITH THE
MAIN QUESTION BEING HOW FAR INLAND A LAKE BREEZE WILL PENETRATE.
CERTAINLY...IT IS LIKELY THAT LAKEFRONT LOCATIONS WILL TURN COOLER
IN THE AFTERNOON...BUT IT IS LESS CERTAIN HOW FAR INLAND THE LAKE
COOLING WILL PENETRATE.  SO...WILL KEEP THE MAX TEMP FORECAST A BIT
ON THE CONSERVATIVE SIDE AS FAR AS LAKE INFLUENCE IS CONCERNED AND
LIMIT THE COOLING TO THE IMMEDIATE LAKEFRONT AND ALLOW MAX TEMPS TO
BE MORE REPRESENTATIVE OF THE LARGE SCALE PATTERN.  UNDER THE COOL
NWLY FLOW ALOFT...HIGHS WILL REMAIN A FEW DEGREES BELOW NORMAL INTO
THE WEEKEND WITH HIGHS AROUND 80F OR SO.  TIMING OF PERIODS OF PCPN
WILL BE LESS CERTAIN THAN THE TEMPERATURE TRENDS FOR THE NEXT FEW
DAYS AND WILL GENERALLY BE DEPENDENT ON THE TIMING OF SHORTWAVE
ENERGY DROPPING THROUGH THE NWLY FLOW ALOFT.  SO...WHILE NO DAY IN
THE SHORT TERM FORECAST PERIOD WILL BE A TOTAL WASHOUT...THERE
SHOULD BE PERIODS OF SCT SHRA AND ISOLD TSRA.

THE LONGER RANGE GUIDANCE IS IN GENERALLY GOOD AGREEMENT ON THE
UPPER LEVEL PATTERN BECOMING MORE PROGRESSIVE THROUGH THE WEEKEND.
THIS WILL INITIATE A WARMING TREND AS THE UPPER LEVEL RIDGING MOVES
OUT OVER THE WESTERN PLAINS ON SUNDAY WHILE THE UPPER LOW OVER JAMES
BAY KICKS OUT TO THE NORTHEAST...LEAVING WEAKER LONGWAVE TROUGHING
OVER THE ERN CONUS.  SUNDAY SHOULD BE A TRANSITIONAL DAY...WITH
INLAND TEMPS A LITTLE HIGHER...BUT A WEAK GRADIENT PERSISTING AT THE
SURFACE WILL ALLOW FOR ANOTHER LAKE BREEZE DAY AND COOLER CONDITIONS
NEAR THE LAKE. RISING HEIGHTS OVER THE MIDWEST SHOULD ALLOW FOR MAX
TEMPS TO CLIMB INTO THE MIDDLE 80S BY MONDAY.

MORE UNCERTAINTY WILL CREEP INTO THE FORECAST DURING THE EXTENDED
FORECAST PERIOD AS FLOW BECOMES MORE ZONAL OVER THE MIDWEST.  IN THE
INCREASINGLY ZONAL FLOW...SHORT WAVE STRENGTH AND TIMING WILL BECOME
MORE UNCERTAIN...SO...CONFIDENCE IN THE SENSIBLE WEATHER FORECAST
WILL INCREASE WITH TIME THROUGH THE EXTENDED FORECAST PERIOD.
HOWEVER...THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THE WARMING
TREND COULD BE BRIEF AS A WEAK UPPER LOW HANGS BACK OVER THE LOWER
MISSISSIPPI VALLEY THROUGH THE PERIOD AND THE UPPER RIDGING WILL NOT
BUILD ANY FARTHER EAST THAN THE CENTRAL PLAINS.  ALSO...THE SFC
PATTERN SHOULD REMAIN WEAK...SO DAILY LAKE BREEZE DEVELOPMENT WILL
BE LIKELY AS WELL. THE TREND FOR THE EXTEDNED FORECAST PERIOD IS
SHAPPING UP FOR MORE BELOW NORMAL TEMPERATURES WITH PERIODIC CHANCES
FOR AT LEAST SOME LIGHT PCPN.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* ISOLATED SHRA/TSRA THURSDAY AFTERNOON. CMS

//DISCUSSION...UPDATED 00Z...

A LAKE BREEZE HAS MOVED WELL WEST OF ORD/MDW LATE THIS AFTERNOON
AND WILL CONTINUE WEST UNTIL IT DISSIPATES THIS EVENING. THE
GRADIENT WILL BE QUITE WEAK TONIGHT AND WINDS WILL EVENTUALLY
BECOME LIGHT AND VARIABLE AND LIKELY CALM IN MANY LOCATIONS. WINDS
WILL BECOME LIGHT WEST/SOUTHWEST AFTER SUNRISE AND REMAIN WESTERLY
THURSDAY WITH SPEEDS INCREASING TO 10-12KTS WITH A FEW HIGHER
GUSTS POSSIBLE IN THE AFTERNOON. WIND SPEEDS APPEAR STRONG ENOUGH
TO PREVENT A LAKE BREEZE FROM REACHING ORD/MDW...BUT A LAKE BREEZE
MAY STILL FORM NEAR THE LAKE.

CU FIELD IS QUICKLY DISSIPATING THIS EVENING AND NOT EXPECTING ANY
ADDITIONAL SHOWERS. SHOWERS AND THUNDERSTORMS OVER NORTHERN WI
WILL MOVE SOUTH THIS EVENING BUT ARE EXPECTED TO DISSIPATE BEFORE
REACHING NORTHERN IL WITH JUST FEW/SCT MID CLOUDS OVERNIGHT.
ISOLATED SHOWERS/THUNDERSTORMS ARE POSSIBLE THURSDAY AFTERNOON
INTO EARLY EVENING.

WITH THE LIGHT WINDS...TEMPS WILL LIKELY COOL TOWARD THE DEWPOINTS
OVERNIGHT AND TOWARD MORNING WITH SOME LIGHT/SHALLOW GROUND FOG
POSSIBLE IN THE USUAL SPOTS AND ADDED FOG MENTION TO DPA. CMS

//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* LOW FOR ISOLATED SHRA/TSRA THURSDAY AFTERNOON. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z...

* FRIDAY AND SATURDAY...AFTERNOON ISOLATED SHRA/TSRA. AFTERNOON
  LAKE BREEZES.
* SUNDAY AND MONDAY...DRY/VFR.
* TUESDAY...CHANCE OF TSRA.

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KILX 302314
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
614 PM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 300 PM CDT Wed Jul 30 2014

An upper level trough across the eastern half of the CONUS will
continue to keep Illinois in an unseasonably cool air mass into the
weekend. Chances of spotty showers or storms will continue through
Saturday, then a dry period may develop as into early next week as
upper level ridging advances into IL. Warmer conditions appear in
the far extended as high temps approach normal on Tue and Wed.

SHORT TERM...Tonight through Saturday.

A few showers bubbled up this afternoon northeast of a line from
Bloomington to Mattoon. Any lightning through 230 pm remained in
Indiana closer to the better mid-level instability. RAP sounding
analysis east of Champaign showed only 150-200 J/kg MLCAPE for
storm updraft development in our counties, which supports the
limited vertical development observed visually and on satellite.
We expect any showers in our northeastern forecast area to
dissipate by 00z/7pm, so no precip was included in the evening
grids. The diurnally driven cumulus will dissipate with the
passage of sunset as well, providing clear skies overnight.
Surface winds will become light and variable tonight, creating
favorable radiational cooling conditions. Lows should dip into the
mid to upper 50s in most locations. A few spots could linger in
the low 60s depending on localized surface dew point trends.

Thursday will be a repeat of Wednesday with a few isolated
afternoon showers east-northeast of PIA to BMI to MTO. Highs
will top out in the low 80s with relatively comfortable dew points
around 60F.

Friday and Saturday will feature the passage of stronger 500mb
shortwaves, increasing the potential and coverage of showers and
storms. We still expect mainly 30-40% coverage on both days, but
thunder potential will be higher due to deeper mid-level
instability and increasing moisture. Highs will still remain below
normal in the low 80s through Saturday.

LONG TERM...Sunday through Wednesday.

The upper level low will shift east of Illinois for Sunday through
Monday with upper level ridging providing dry conditions both days.
Slow warming will begin...with highs by Monday approaching the
middle 80s. Storm chances are expected to return on Tuesday and
Wednesday the next series of shortwaves roll over the top of the
ridge in the Plains. No strong to severe weather is anticipated at
this point. A warm front developing north of IL will help
southerly flow bring mid to upper 80s into our forecast area,
which are closer to normal for early Aug.

Shimon

&&

.AVIATION...
ISSUED 610 PM CDT Wed Jul 30 2014

Little change needed to the going TAF set. Diurnal cumulus is
quickly fading, and any lingering clouds around 6000 feet will be
going away over the next hour or two. Scattered clouds expected to
redevelop again toward 15Z or so. Cannot rule out a stray
afternoon shower from KPIA-KCMI, but chances are too low to
include a mention.

Geelhart

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$





000
FXUS63 KILX 302314
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
614 PM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 300 PM CDT Wed Jul 30 2014

An upper level trough across the eastern half of the CONUS will
continue to keep Illinois in an unseasonably cool air mass into the
weekend. Chances of spotty showers or storms will continue through
Saturday, then a dry period may develop as into early next week as
upper level ridging advances into IL. Warmer conditions appear in
the far extended as high temps approach normal on Tue and Wed.

SHORT TERM...Tonight through Saturday.

A few showers bubbled up this afternoon northeast of a line from
Bloomington to Mattoon. Any lightning through 230 pm remained in
Indiana closer to the better mid-level instability. RAP sounding
analysis east of Champaign showed only 150-200 J/kg MLCAPE for
storm updraft development in our counties, which supports the
limited vertical development observed visually and on satellite.
We expect any showers in our northeastern forecast area to
dissipate by 00z/7pm, so no precip was included in the evening
grids. The diurnally driven cumulus will dissipate with the
passage of sunset as well, providing clear skies overnight.
Surface winds will become light and variable tonight, creating
favorable radiational cooling conditions. Lows should dip into the
mid to upper 50s in most locations. A few spots could linger in
the low 60s depending on localized surface dew point trends.

Thursday will be a repeat of Wednesday with a few isolated
afternoon showers east-northeast of PIA to BMI to MTO. Highs
will top out in the low 80s with relatively comfortable dew points
around 60F.

Friday and Saturday will feature the passage of stronger 500mb
shortwaves, increasing the potential and coverage of showers and
storms. We still expect mainly 30-40% coverage on both days, but
thunder potential will be higher due to deeper mid-level
instability and increasing moisture. Highs will still remain below
normal in the low 80s through Saturday.

LONG TERM...Sunday through Wednesday.

The upper level low will shift east of Illinois for Sunday through
Monday with upper level ridging providing dry conditions both days.
Slow warming will begin...with highs by Monday approaching the
middle 80s. Storm chances are expected to return on Tuesday and
Wednesday the next series of shortwaves roll over the top of the
ridge in the Plains. No strong to severe weather is anticipated at
this point. A warm front developing north of IL will help
southerly flow bring mid to upper 80s into our forecast area,
which are closer to normal for early Aug.

Shimon

&&

.AVIATION...
ISSUED 610 PM CDT Wed Jul 30 2014

Little change needed to the going TAF set. Diurnal cumulus is
quickly fading, and any lingering clouds around 6000 feet will be
going away over the next hour or two. Scattered clouds expected to
redevelop again toward 15Z or so. Cannot rule out a stray
afternoon shower from KPIA-KCMI, but chances are too low to
include a mention.

Geelhart

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$





000
FXUS63 KILX 302314
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
614 PM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 300 PM CDT Wed Jul 30 2014

An upper level trough across the eastern half of the CONUS will
continue to keep Illinois in an unseasonably cool air mass into the
weekend. Chances of spotty showers or storms will continue through
Saturday, then a dry period may develop as into early next week as
upper level ridging advances into IL. Warmer conditions appear in
the far extended as high temps approach normal on Tue and Wed.

SHORT TERM...Tonight through Saturday.

A few showers bubbled up this afternoon northeast of a line from
Bloomington to Mattoon. Any lightning through 230 pm remained in
Indiana closer to the better mid-level instability. RAP sounding
analysis east of Champaign showed only 150-200 J/kg MLCAPE for
storm updraft development in our counties, which supports the
limited vertical development observed visually and on satellite.
We expect any showers in our northeastern forecast area to
dissipate by 00z/7pm, so no precip was included in the evening
grids. The diurnally driven cumulus will dissipate with the
passage of sunset as well, providing clear skies overnight.
Surface winds will become light and variable tonight, creating
favorable radiational cooling conditions. Lows should dip into the
mid to upper 50s in most locations. A few spots could linger in
the low 60s depending on localized surface dew point trends.

Thursday will be a repeat of Wednesday with a few isolated
afternoon showers east-northeast of PIA to BMI to MTO. Highs
will top out in the low 80s with relatively comfortable dew points
around 60F.

Friday and Saturday will feature the passage of stronger 500mb
shortwaves, increasing the potential and coverage of showers and
storms. We still expect mainly 30-40% coverage on both days, but
thunder potential will be higher due to deeper mid-level
instability and increasing moisture. Highs will still remain below
normal in the low 80s through Saturday.

LONG TERM...Sunday through Wednesday.

The upper level low will shift east of Illinois for Sunday through
Monday with upper level ridging providing dry conditions both days.
Slow warming will begin...with highs by Monday approaching the
middle 80s. Storm chances are expected to return on Tuesday and
Wednesday the next series of shortwaves roll over the top of the
ridge in the Plains. No strong to severe weather is anticipated at
this point. A warm front developing north of IL will help
southerly flow bring mid to upper 80s into our forecast area,
which are closer to normal for early Aug.

Shimon

&&

.AVIATION...
ISSUED 610 PM CDT Wed Jul 30 2014

Little change needed to the going TAF set. Diurnal cumulus is
quickly fading, and any lingering clouds around 6000 feet will be
going away over the next hour or two. Scattered clouds expected to
redevelop again toward 15Z or so. Cannot rule out a stray
afternoon shower from KPIA-KCMI, but chances are too low to
include a mention.

Geelhart

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$





000
FXUS63 KILX 302314
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
614 PM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 300 PM CDT Wed Jul 30 2014

An upper level trough across the eastern half of the CONUS will
continue to keep Illinois in an unseasonably cool air mass into the
weekend. Chances of spotty showers or storms will continue through
Saturday, then a dry period may develop as into early next week as
upper level ridging advances into IL. Warmer conditions appear in
the far extended as high temps approach normal on Tue and Wed.

SHORT TERM...Tonight through Saturday.

A few showers bubbled up this afternoon northeast of a line from
Bloomington to Mattoon. Any lightning through 230 pm remained in
Indiana closer to the better mid-level instability. RAP sounding
analysis east of Champaign showed only 150-200 J/kg MLCAPE for
storm updraft development in our counties, which supports the
limited vertical development observed visually and on satellite.
We expect any showers in our northeastern forecast area to
dissipate by 00z/7pm, so no precip was included in the evening
grids. The diurnally driven cumulus will dissipate with the
passage of sunset as well, providing clear skies overnight.
Surface winds will become light and variable tonight, creating
favorable radiational cooling conditions. Lows should dip into the
mid to upper 50s in most locations. A few spots could linger in
the low 60s depending on localized surface dew point trends.

Thursday will be a repeat of Wednesday with a few isolated
afternoon showers east-northeast of PIA to BMI to MTO. Highs
will top out in the low 80s with relatively comfortable dew points
around 60F.

Friday and Saturday will feature the passage of stronger 500mb
shortwaves, increasing the potential and coverage of showers and
storms. We still expect mainly 30-40% coverage on both days, but
thunder potential will be higher due to deeper mid-level
instability and increasing moisture. Highs will still remain below
normal in the low 80s through Saturday.

LONG TERM...Sunday through Wednesday.

The upper level low will shift east of Illinois for Sunday through
Monday with upper level ridging providing dry conditions both days.
Slow warming will begin...with highs by Monday approaching the
middle 80s. Storm chances are expected to return on Tuesday and
Wednesday the next series of shortwaves roll over the top of the
ridge in the Plains. No strong to severe weather is anticipated at
this point. A warm front developing north of IL will help
southerly flow bring mid to upper 80s into our forecast area,
which are closer to normal for early Aug.

Shimon

&&

.AVIATION...
ISSUED 610 PM CDT Wed Jul 30 2014

Little change needed to the going TAF set. Diurnal cumulus is
quickly fading, and any lingering clouds around 6000 feet will be
going away over the next hour or two. Scattered clouds expected to
redevelop again toward 15Z or so. Cannot rule out a stray
afternoon shower from KPIA-KCMI, but chances are too low to
include a mention.

Geelhart

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$





000
FXUS63 KLOT 302202
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
502 PM CDT WED JUL 30 2014

.DISCUSSION...
254 PM CDT

A HIGH AMPLITUDE LONGWAVE PATTERN THAT HAS BEEN IN PLACE FOR THE
PAST FEW DAYS WILL PERSIST FOR THE NEXT FEW DAYS WITH DEEP LONG WAVE
TROUGHING OVER THE ERN CONUS AND AN UPPER LOW CENTER OVER JAMES
BAY...WITH RIDGING OVER THE WRN CONUS.  THE LOCAL AREA WILL REMAIN
UNDER GENERALLY NWLY FLOW ALOFT UNDER THE SWRN PERIPHERY OF THE
UPPER LOW.  THIS WILL ALLOW FOR A SERIES OF WEAK SHORT WAVES TO
RIPPLE THROUGH THE NWLY FLOW ALOFT OVER THE LOCAL AREA.

FOR THE REMAINDER OF THIS AFTERNOON AND THIS EVENING...THE MAIN
CONCERN WILL BE THE LAKE BREEZE BOUNDARY QUICKLY PUSHING INLAND
THROUGH NERN IL AND NWRN IN.  TEMPERATURES WILL DROP OFF SEVERAL
DEGREES WITH THE PASSAGE OF THE BOUNDARY AND LAKEFRONT LOCATIONS
HAVE ALREADY DROPPED INTO THE MIDDLE 60S.  THE ENVIRONMENT AHEAD OF
THE BOUNDARY IS MODESTLY MOIST AND UNSTABLE.  WITH CYCLONIC FLOW
ALOFT...DIURNAL CU HAS BEEN DEVELOPING OVER THE REGION PER THE LATEST
SATELLITE IMAGERY.  AS OF EARLY THIS AFTERNOON...HAVE NOT SEEN ANY
SHRA/TSRA ACTIVITY OVER NRN IL/NWRN IN...BUT THE REGION REMAINS
MODESTLY UNSTABLE WITH DEWPOINTS IN THE MIDDLE TO UPPER 50S.  THERE
WILL STILL BE A CHANCE FOR SOME SHRA/TSRA FOCUSED ALONG THE LAKE
BREEZE BOUNDARY AS WELL AS SOME ISOLD SHRA OR AN EVEN MORE ISOLD TS
OVER THE AREA THROUGH SUNSET.  DURG THE EVENING AND INTO THE
OVERNIGHT HOURS...ANY DIURNAL PCPN WILL DISSIPATE AND AND RESIDUAL
PCPN WILL BE WELL NORTH OF THE AREA INVOF ON OF THE SEEMINGLY
ENDLESS SERIES OF IMPULSES DROPPING THROUGH THE NORTHWEST FLOW.

LITTLE CHANGE IS EXPECTED FOR TOMORROW THROUGH SATURDAY AS THE
SYNOPTIC SCALE PATTERN SHOULD CHANGE LITTLE AND A WEAK GRADIENT
PATTERN WILL PERSIST AT THE SFC.  UNDER PERSISTENT NWLY FLOW
ALOFT...THE SERIES OF WEAK SHORTWAVES WILL CONTINUE TO BRING
PERIODIC CHANCES FOR SCT SHRA AND ISOLD TSRA...WITH THE BETTER
CHANCES FOR TS DURG THE AFTERNOON HOURS.  THE WEAK GRADIENT PATTERN
AT THE SFC SHOULD ALLOW FOR DAILY LAKE BREEZE DEVELOPMENT...WITH THE
MAIN QUESTION BEING HOW FAR INLAND A LAKE BREEZE WILL PENETRATE.
CERTAINLY...IT IS LIKELY THAT LAKEFRONT LOCATIONS WILL TURN COOLER
IN THE AFTERNOON...BUT IT IS LESS CERTAIN HOW FAR INLAND THE LAKE
COOLING WILL PENETRATE.  SO...WILL KEEP THE MAX TEMP FORECAST A BIT
ON THE CONSERVATIVE SIDE AS FAR AS LAKE INFLUENCE IS CONCERNED AND
LIMIT THE COOLING TO THE IMMEDIATE LAKEFRONT AND ALLOW MAX TEMPS TO
BE MORE REPRESENTATIVE OF THE LARGE SCALE PATTERN.  UNDER THE COOL
NWLY FLOW ALOFT...HIGHS WILL REMAIN A FEW DEGREES BELOW NORMAL INTO
THE WEEKEND WITH HIGHS AROUND 80F OR SO.  TIMING OF PERIODS OF PCPN
WILL BE LESS CERTAIN THAN THE TEMPERATURE TRENDS FOR THE NEXT FEW
DAYS AND WILL GENERALLY BE DEPENDENT ON THE TIMING OF SHORTWAVE
ENERGY DROPPING THROUGH THE NWLY FLOW ALOFT.  SO...WHILE NO DAY IN
THE SHORT TERM FORECAST PERIOD WILL BE A TOTAL WASHOUT...THERE
SHOULD BE PERIODS OF SCT SHRA AND ISOLD TSRA.

THE LONGER RANGE GUIDANCE IS IN GENERALLY GOOD AGREEMENT ON THE
UPPER LEVEL PATTERN BECOMING MORE PROGRESSIVE THROUGH THE WEEKEND.
THIS WILL INITIATE A WARMING TREND AS THE UPPER LEVEL RIDGING MOVES
OUT OVER THE WESTERN PLAINS ON SUNDAY WHILE THE UPPER LOW OVER JAMES
BAY KICKS OUT TO THE NORTHEAST...LEAVING WEAKER LONGWAVE TROUGHING
OVER THE ERN CONUS.  SUNDAY SHOULD BE A TRANSITIONAL DAY...WITH
INLAND TEMPS A LITTLE HIGHER...BUT A WEAK GRADIENT PERSISTING AT THE
SURFACE WILL ALLOW FOR ANOTHER LAKE BREEZE DAY AND COOLER CONDITIONS
NEAR THE LAKE. RISING HEIGHTS OVER THE MIDWEST SHOULD ALLOW FOR MAX
TEMPS TO CLIMB INTO THE MIDDLE 80S BY MONDAY.

MORE UNCERTAINTY WILL CREEP INTO THE FORECAST DURING THE EXTENDED
FORECAST PERIOD AS FLOW BECOMES MORE ZONAL OVER THE MIDWEST.  IN THE
INCREASINGLY ZONAL FLOW...SHORT WAVE STRENGTH AND TIMING WILL BECOME
MORE UNCERTAIN...SO...CONFIDENCE IN THE SENSIBLE WEATHER FORECAST
WILL INCREASE WITH TIME THROUGH THE EXTENDED FORECAST PERIOD.
HOWEVER...THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THE WARMING
TREND COULD BE BRIEF AS A WEAK UPPER LOW HANGS BACK OVER THE LOWER
MISSISSIPPI VALLEY THROUGH THE PERIOD AND THE UPPER RIDGING WILL NOT
BUILD ANY FARTHER EAST THAN THE CENTRAL PLAINS.  ALSO...THE SFC
PATTERN SHOULD REMAIN WEAK...SO DAILY LAKE BREEZE DEVELOPMENT WILL
BE LIKELY AS WELL. THE TREND FOR THE EXTEDNED FORECAST PERIOD IS
SHAPPING UP FOR MORE BELOW NORMAL TEMPERATURES WITH PERIODIC CHANCES
FOR AT LEAST SOME LIGHT PCPN.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* EAST/NORTHEAST WINDS JUST UNDER 10 KTS THRU EARLY EVENING.
* ISOLATED SHRA/TSRA THROUGH MID EVENING. CMS

//DISCUSSION...UPDATED 18Z...

A LIGHT WIND FIELD ACROSS THE AREA IS ALLOWING A LAKE BREEZE TO
MAKE SOME GOOD PROGRESS INLAND ACROSS NORTHEASTERN ILLINOIS EARLY
THIS AFTERNOON. CURRENT TIMING LOOKS TO PUT THE BOUNDARY THROUGH
KMDW AROUND 1930 UTC AND THROUGH KORD IN THE 20 TO 21 UTC TIME
FRAME. WINDS DO NOT APPEAR TO BE OVERLY STRONG BEHIND THE LAKE
BREEZE...WITH GENERALLY ONLY AROUND 10 KT OF EAST-NORTHEASTERLY
FLOW EXPECTED. THE WINDS WILL GRADUALLY SHIFT BACK OUT OF THE
WEST-SOUTHWEST TONIGHT INTO THURSDAY. ANOTHER LAKE BREEZE MAY
DEVELOP ON THURSDAY. HOWEVER...WITH A SLIGHTLY STRONGER WEST-
SOUTHWESTERLY WIND FIELD EXPECTED ON THURSDAY...THE LAKE BREEZE
MAY STRUGGLE TO REACH THE TERMINALS.

THE OTHER CONCERN THIS AFTERNOON WILL...SIMILAR TO YESTERDAY...BE
THE THREAT FOR SOME WIDELY SCATTERED SHOWERS AND PERHAPS A
THUNDERSTORM ACROSS THE AREA. CUMULUS CLOUDS WILL LIKELY BE ON AN
UPTICK OVER THE NEXT HOUR OR SO AS TEMPERATURES CONTINUE TO WARM
THROUGH THE MID AND UPPER 70S. THIS CLOUD COVER COULD EVEN LEAD TO A
PERIOD OF LOWER END VFR CIG AROUND 4000 FEET AGL...ESPECIALLY AHEAD
OF THE LAKE BREEZE BOUNDARY. GIVEN THE LOWER AREAL COVERAGE
EXPECTED...I WILL CONTINUE WITH THE VCSH AND LEAVE THE MENTION OF
THUNDER OUT OF THE TAF AT THIS TIME.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* HIGH FOR WINDS THROUGH THURSDAY MORNING...MEDIUM THURSDAY
  AFTERNOON.
* LOW FOR ISOLATED SHRA/TSRA THROUGH MID EVENING. CMS

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SCHC TSRA EARLY IN THE EVENING...SCHC SHRA LATE
IN THE EVENING.

FRIDAY...CHC SHRA WITH A CHC OF TSRA IN THE AFTN.

SATURDAY...SCHC SHRA IN THE MORNING...CHC OF TSRA IN THE AFTN.

SUNDAY...VFR.

MONDAY...CHC TSRA OVERNIGHT.

TUESDAY...CHC TSRA.

JEE

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 302202
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
502 PM CDT WED JUL 30 2014

.DISCUSSION...
254 PM CDT

A HIGH AMPLITUDE LONGWAVE PATTERN THAT HAS BEEN IN PLACE FOR THE
PAST FEW DAYS WILL PERSIST FOR THE NEXT FEW DAYS WITH DEEP LONG WAVE
TROUGHING OVER THE ERN CONUS AND AN UPPER LOW CENTER OVER JAMES
BAY...WITH RIDGING OVER THE WRN CONUS.  THE LOCAL AREA WILL REMAIN
UNDER GENERALLY NWLY FLOW ALOFT UNDER THE SWRN PERIPHERY OF THE
UPPER LOW.  THIS WILL ALLOW FOR A SERIES OF WEAK SHORT WAVES TO
RIPPLE THROUGH THE NWLY FLOW ALOFT OVER THE LOCAL AREA.

FOR THE REMAINDER OF THIS AFTERNOON AND THIS EVENING...THE MAIN
CONCERN WILL BE THE LAKE BREEZE BOUNDARY QUICKLY PUSHING INLAND
THROUGH NERN IL AND NWRN IN.  TEMPERATURES WILL DROP OFF SEVERAL
DEGREES WITH THE PASSAGE OF THE BOUNDARY AND LAKEFRONT LOCATIONS
HAVE ALREADY DROPPED INTO THE MIDDLE 60S.  THE ENVIRONMENT AHEAD OF
THE BOUNDARY IS MODESTLY MOIST AND UNSTABLE.  WITH CYCLONIC FLOW
ALOFT...DIURNAL CU HAS BEEN DEVELOPING OVER THE REGION PER THE LATEST
SATELLITE IMAGERY.  AS OF EARLY THIS AFTERNOON...HAVE NOT SEEN ANY
SHRA/TSRA ACTIVITY OVER NRN IL/NWRN IN...BUT THE REGION REMAINS
MODESTLY UNSTABLE WITH DEWPOINTS IN THE MIDDLE TO UPPER 50S.  THERE
WILL STILL BE A CHANCE FOR SOME SHRA/TSRA FOCUSED ALONG THE LAKE
BREEZE BOUNDARY AS WELL AS SOME ISOLD SHRA OR AN EVEN MORE ISOLD TS
OVER THE AREA THROUGH SUNSET.  DURG THE EVENING AND INTO THE
OVERNIGHT HOURS...ANY DIURNAL PCPN WILL DISSIPATE AND AND RESIDUAL
PCPN WILL BE WELL NORTH OF THE AREA INVOF ON OF THE SEEMINGLY
ENDLESS SERIES OF IMPULSES DROPPING THROUGH THE NORTHWEST FLOW.

LITTLE CHANGE IS EXPECTED FOR TOMORROW THROUGH SATURDAY AS THE
SYNOPTIC SCALE PATTERN SHOULD CHANGE LITTLE AND A WEAK GRADIENT
PATTERN WILL PERSIST AT THE SFC.  UNDER PERSISTENT NWLY FLOW
ALOFT...THE SERIES OF WEAK SHORTWAVES WILL CONTINUE TO BRING
PERIODIC CHANCES FOR SCT SHRA AND ISOLD TSRA...WITH THE BETTER
CHANCES FOR TS DURG THE AFTERNOON HOURS.  THE WEAK GRADIENT PATTERN
AT THE SFC SHOULD ALLOW FOR DAILY LAKE BREEZE DEVELOPMENT...WITH THE
MAIN QUESTION BEING HOW FAR INLAND A LAKE BREEZE WILL PENETRATE.
CERTAINLY...IT IS LIKELY THAT LAKEFRONT LOCATIONS WILL TURN COOLER
IN THE AFTERNOON...BUT IT IS LESS CERTAIN HOW FAR INLAND THE LAKE
COOLING WILL PENETRATE.  SO...WILL KEEP THE MAX TEMP FORECAST A BIT
ON THE CONSERVATIVE SIDE AS FAR AS LAKE INFLUENCE IS CONCERNED AND
LIMIT THE COOLING TO THE IMMEDIATE LAKEFRONT AND ALLOW MAX TEMPS TO
BE MORE REPRESENTATIVE OF THE LARGE SCALE PATTERN.  UNDER THE COOL
NWLY FLOW ALOFT...HIGHS WILL REMAIN A FEW DEGREES BELOW NORMAL INTO
THE WEEKEND WITH HIGHS AROUND 80F OR SO.  TIMING OF PERIODS OF PCPN
WILL BE LESS CERTAIN THAN THE TEMPERATURE TRENDS FOR THE NEXT FEW
DAYS AND WILL GENERALLY BE DEPENDENT ON THE TIMING OF SHORTWAVE
ENERGY DROPPING THROUGH THE NWLY FLOW ALOFT.  SO...WHILE NO DAY IN
THE SHORT TERM FORECAST PERIOD WILL BE A TOTAL WASHOUT...THERE
SHOULD BE PERIODS OF SCT SHRA AND ISOLD TSRA.

THE LONGER RANGE GUIDANCE IS IN GENERALLY GOOD AGREEMENT ON THE
UPPER LEVEL PATTERN BECOMING MORE PROGRESSIVE THROUGH THE WEEKEND.
THIS WILL INITIATE A WARMING TREND AS THE UPPER LEVEL RIDGING MOVES
OUT OVER THE WESTERN PLAINS ON SUNDAY WHILE THE UPPER LOW OVER JAMES
BAY KICKS OUT TO THE NORTHEAST...LEAVING WEAKER LONGWAVE TROUGHING
OVER THE ERN CONUS.  SUNDAY SHOULD BE A TRANSITIONAL DAY...WITH
INLAND TEMPS A LITTLE HIGHER...BUT A WEAK GRADIENT PERSISTING AT THE
SURFACE WILL ALLOW FOR ANOTHER LAKE BREEZE DAY AND COOLER CONDITIONS
NEAR THE LAKE. RISING HEIGHTS OVER THE MIDWEST SHOULD ALLOW FOR MAX
TEMPS TO CLIMB INTO THE MIDDLE 80S BY MONDAY.

MORE UNCERTAINTY WILL CREEP INTO THE FORECAST DURING THE EXTENDED
FORECAST PERIOD AS FLOW BECOMES MORE ZONAL OVER THE MIDWEST.  IN THE
INCREASINGLY ZONAL FLOW...SHORT WAVE STRENGTH AND TIMING WILL BECOME
MORE UNCERTAIN...SO...CONFIDENCE IN THE SENSIBLE WEATHER FORECAST
WILL INCREASE WITH TIME THROUGH THE EXTENDED FORECAST PERIOD.
HOWEVER...THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THE WARMING
TREND COULD BE BRIEF AS A WEAK UPPER LOW HANGS BACK OVER THE LOWER
MISSISSIPPI VALLEY THROUGH THE PERIOD AND THE UPPER RIDGING WILL NOT
BUILD ANY FARTHER EAST THAN THE CENTRAL PLAINS.  ALSO...THE SFC
PATTERN SHOULD REMAIN WEAK...SO DAILY LAKE BREEZE DEVELOPMENT WILL
BE LIKELY AS WELL. THE TREND FOR THE EXTEDNED FORECAST PERIOD IS
SHAPPING UP FOR MORE BELOW NORMAL TEMPERATURES WITH PERIODIC CHANCES
FOR AT LEAST SOME LIGHT PCPN.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* EAST/NORTHEAST WINDS JUST UNDER 10 KTS THRU EARLY EVENING.
* ISOLATED SHRA/TSRA THROUGH MID EVENING. CMS

//DISCUSSION...UPDATED 18Z...

A LIGHT WIND FIELD ACROSS THE AREA IS ALLOWING A LAKE BREEZE TO
MAKE SOME GOOD PROGRESS INLAND ACROSS NORTHEASTERN ILLINOIS EARLY
THIS AFTERNOON. CURRENT TIMING LOOKS TO PUT THE BOUNDARY THROUGH
KMDW AROUND 1930 UTC AND THROUGH KORD IN THE 20 TO 21 UTC TIME
FRAME. WINDS DO NOT APPEAR TO BE OVERLY STRONG BEHIND THE LAKE
BREEZE...WITH GENERALLY ONLY AROUND 10 KT OF EAST-NORTHEASTERLY
FLOW EXPECTED. THE WINDS WILL GRADUALLY SHIFT BACK OUT OF THE
WEST-SOUTHWEST TONIGHT INTO THURSDAY. ANOTHER LAKE BREEZE MAY
DEVELOP ON THURSDAY. HOWEVER...WITH A SLIGHTLY STRONGER WEST-
SOUTHWESTERLY WIND FIELD EXPECTED ON THURSDAY...THE LAKE BREEZE
MAY STRUGGLE TO REACH THE TERMINALS.

THE OTHER CONCERN THIS AFTERNOON WILL...SIMILAR TO YESTERDAY...BE
THE THREAT FOR SOME WIDELY SCATTERED SHOWERS AND PERHAPS A
THUNDERSTORM ACROSS THE AREA. CUMULUS CLOUDS WILL LIKELY BE ON AN
UPTICK OVER THE NEXT HOUR OR SO AS TEMPERATURES CONTINUE TO WARM
THROUGH THE MID AND UPPER 70S. THIS CLOUD COVER COULD EVEN LEAD TO A
PERIOD OF LOWER END VFR CIG AROUND 4000 FEET AGL...ESPECIALLY AHEAD
OF THE LAKE BREEZE BOUNDARY. GIVEN THE LOWER AREAL COVERAGE
EXPECTED...I WILL CONTINUE WITH THE VCSH AND LEAVE THE MENTION OF
THUNDER OUT OF THE TAF AT THIS TIME.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* HIGH FOR WINDS THROUGH THURSDAY MORNING...MEDIUM THURSDAY
  AFTERNOON.
* LOW FOR ISOLATED SHRA/TSRA THROUGH MID EVENING. CMS

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SCHC TSRA EARLY IN THE EVENING...SCHC SHRA LATE
IN THE EVENING.

FRIDAY...CHC SHRA WITH A CHC OF TSRA IN THE AFTN.

SATURDAY...SCHC SHRA IN THE MORNING...CHC OF TSRA IN THE AFTN.

SUNDAY...VFR.

MONDAY...CHC TSRA OVERNIGHT.

TUESDAY...CHC TSRA.

JEE

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KILX 302000
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
300 PM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 300 PM CDT Wed Jul 30 2014

An upper level trough across the eastern half of the CONUS will
continue to keep Illinois in an unseasonably cool airmass into the
weekend. Chances of spotty showers or storms will continue through
Saturday, then a dry period may develop as into early next week as
upper level ridging advances into IL. Warmer conditions appear in
the far extended as high temps approach normal on Tue and Wed.

SHORT TERM...Tonight through Saturday.

A few showers bubbled up this afternoon northeast of a line from
Bloomington to Mattoon. Any lightning through 230 pm remained in
Indiana closer to the better mid-level instability. RAP sounding
analysis east of Champaign showed only 150-200 J/kg MLCAPE for
storm updraft development in our counties, which supports the
limited vertical development observed visually and on satellite.
We expect any showers in our northeastern forecast area to
dissipate by 00z/7pm, so no precip was included in the evening
grids. The diurnally driven cumulus will dissipate with the
passage of sunset as well, providing clear skies overnight.
Surface winds will become light and variable tonight, creating
favorable radiational cooling conditions. Lows should dip into the
mid to upper 50s in most locations. A few spots could linger in
the low 60s depending on localized surface dewpoint trends.

Thursday will be a repeat of Wednesday with a few isolated
afternoon showers east-northeast of PIA to BMI to MTO. Highs
will top out in the low 80s with relatively comfortable dewpoints
around 60F.

Friday and Saturday will feature the passage of stronger 500mb
shortwaves, increasing the potential and coverage of showers and
storms. We still expect mainly 30-40% coverage on both days, but
thunder potential will be higher due to deeper mid-level
instability and increasing moisture. Highs will still remain below
normal in the low 80s through Saturday.

LONG TERM...Sunday through Wednesday.

The upper level low will shift east of Illinois for Sunday through
Monday with upper level ridging providing dry conditions both days.
Slow warming will begin...with highs by Monday approaching the
middle 80s. Storm chances are expected to return on Tuesday and
Wednesday the next series of shortwaves roll over the top of the
ridge in the Plains. No strong to severe weather is anticipated at
this point. A warm front developing north of IL will help
southerly flow bring mid to upper 80s into our forecast area,
which are closer to normal for early Aug.

Shimon
&&

.AVIATION...
ISSUED 1242 PM CDT Wed Jul 30 2014

VFR conditions will prevail through the entire 18z TAF period. SCT
to occasionally BKN diurnal clouds at 4000-5000ft this afternoon
will rapidly dissipate toward sunset, with clear skies expected
overnight. The cycle will repeat on Thursday, with SCT diurnal
cloud cover once again developing by late morning/early afternoon.
Winds will be light from the NW this afternoon, then will shift to
the W/SW on Thursday.

Barnes
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$







000
FXUS63 KILX 302000
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
300 PM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 300 PM CDT Wed Jul 30 2014

An upper level trough across the eastern half of the CONUS will
continue to keep Illinois in an unseasonably cool airmass into the
weekend. Chances of spotty showers or storms will continue through
Saturday, then a dry period may develop as into early next week as
upper level ridging advances into IL. Warmer conditions appear in
the far extended as high temps approach normal on Tue and Wed.

SHORT TERM...Tonight through Saturday.

A few showers bubbled up this afternoon northeast of a line from
Bloomington to Mattoon. Any lightning through 230 pm remained in
Indiana closer to the better mid-level instability. RAP sounding
analysis east of Champaign showed only 150-200 J/kg MLCAPE for
storm updraft development in our counties, which supports the
limited vertical development observed visually and on satellite.
We expect any showers in our northeastern forecast area to
dissipate by 00z/7pm, so no precip was included in the evening
grids. The diurnally driven cumulus will dissipate with the
passage of sunset as well, providing clear skies overnight.
Surface winds will become light and variable tonight, creating
favorable radiational cooling conditions. Lows should dip into the
mid to upper 50s in most locations. A few spots could linger in
the low 60s depending on localized surface dewpoint trends.

Thursday will be a repeat of Wednesday with a few isolated
afternoon showers east-northeast of PIA to BMI to MTO. Highs
will top out in the low 80s with relatively comfortable dewpoints
around 60F.

Friday and Saturday will feature the passage of stronger 500mb
shortwaves, increasing the potential and coverage of showers and
storms. We still expect mainly 30-40% coverage on both days, but
thunder potential will be higher due to deeper mid-level
instability and increasing moisture. Highs will still remain below
normal in the low 80s through Saturday.

LONG TERM...Sunday through Wednesday.

The upper level low will shift east of Illinois for Sunday through
Monday with upper level ridging providing dry conditions both days.
Slow warming will begin...with highs by Monday approaching the
middle 80s. Storm chances are expected to return on Tuesday and
Wednesday the next series of shortwaves roll over the top of the
ridge in the Plains. No strong to severe weather is anticipated at
this point. A warm front developing north of IL will help
southerly flow bring mid to upper 80s into our forecast area,
which are closer to normal for early Aug.

Shimon
&&

.AVIATION...
ISSUED 1242 PM CDT Wed Jul 30 2014

VFR conditions will prevail through the entire 18z TAF period. SCT
to occasionally BKN diurnal clouds at 4000-5000ft this afternoon
will rapidly dissipate toward sunset, with clear skies expected
overnight. The cycle will repeat on Thursday, with SCT diurnal
cloud cover once again developing by late morning/early afternoon.
Winds will be light from the NW this afternoon, then will shift to
the W/SW on Thursday.

Barnes
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 301955
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
255 PM CDT WED JUL 30 2014

.DISCUSSION...
254 PM CDT

A HIGH AMPLITUDE LONGWAVE PATTERN THAT HAS BEEN IN PLACE FOR THE
PAST FEW DAYS WILL PERSIST FOR THE NEXT FEW DAYS WITH DEEP LONG WAVE
TROUGHING OVER THE ERN CONUS AND AN UPPER LOW CENTER OVER JAMES
BAY...WITH RIDGING OVER THE WRN CONUS.  THE LOCAL AREA WILL REMAIN
UNDER GENERALLY NWLY FLOW ALOFT UNDER THE SWRN PERIPHERY OF THE
UPPER LOW.  THIS WILL ALLOW FOR A SERIES OF WEAK SHORT WAVES TO
RIPPLE THROUGH THE NWLY FLOW ALOFT OVER THE LOCAL AREA.

FOR THE REMAINDER OF THIS AFTERNOON AND THIS EVENING...THE MAIN
CONCERN WILL BE THE LAKE BREEZE BOUNDARY QUICKLY PUSHING INLAND
THROUGH NERN IL AND NWRN IN.  TEMPERATURES WILL DROP OFF SEVERAL
DEGREES WITH THE PASSAGE OF THE BOUNDARY AND LAKEFRONT LOCATIONS
HAVE ALREADY DROPPED INTO THE MIDDLE 60S.  THE ENVIRONMENT AHEAD OF
THE BOUNDARY IS MODESTLY MOIST AND UNSTABLE.  WITH CYCLONIC FLOW
ALOFT...DIURNAL CU HAS BEEN DEVELOPING OVER THE REGION PER THE LATEST
SATELLITE IMAGERY.  AS OF EARLY THIS AFTERNOON...HAVE NOT SEEN ANY
SHRA/TSRA ACTIVITY OVER NRN IL/NWRN IN...BUT THE REGION REMAINS
MODESTLY UNSTABLE WITH DEWPOINTS IN THE MIDDLE TO UPPER 50S.  THERE
WILL STILL BE A CHANCE FOR SOME SHRA/TSRA FOCUSED ALONG THE LAKE
BREEZE BOUNDARY AS WELL AS SOME ISOLD SHRA OR AN EVEN MORE ISOLD TS
OVER THE AREA THROUGH SUNSET.  DURG THE EVENING AND INTO THE
OVERNIGHT HOURS...ANY DIURNAL PCPN WILL DISSIPATE AND AND RESIDUAL
PCPN WILL BE WELL NORTH OF THE AREA INVOF ON OF THE SEEMINGLY
ENDLESS SERIES OF IMPULSES DROPPING THROUGH THE NORTHWEST FLOW.

LITTLE CHANGE IS EXPECTED FOR TOMORROW THROUGH SATURDAY AS THE
SYNOPTIC SCALE PATTERN SHOULD CHANGE LITTLE AND A WEAK GRADIENT
PATTERN WILL PERSIST AT THE SFC.  UNDER PERSISTENT NWLY FLOW
ALOFT...THE SERIES OF WEAK SHORTWAVES WILL CONTINUE TO BRING
PERIODIC CHANCES FOR SCT SHRA AND ISOLD TSRA...WITH THE BETTER
CHANCES FOR TS DURG THE AFTERNOON HOURS.  THE WEAK GRADIENT PATTERN
AT THE SFC SHOULD ALLOW FOR DAILY LAKE BREEZE DEVELOPMENT...WITH THE
MAIN QUESTION BEING HOW FAR INLAND A LAKE BREEZE WILL PENETRATE.
CERTAINLY...IT IS LIKELY THAT LAKEFRONT LOCATIONS WILL TURN COOLER
IN THE AFTERNOON...BUT IT IS LESS CERTAIN HOW FAR INLAND THE LAKE
COOLING WILL PENETRATE.  SO...WILL KEEP THE MAX TEMP FORECAST A BIT
ON THE CONSERVATIVE SIDE AS FAR AS LAKE INFLUENCE IS CONCERNED AND
LIMIT THE COOLING TO THE IMMEDIATE LAKEFRONT AND ALLOW MAX TEMPS TO
BE MORE REPRESENTATIVE OF THE LARGE SCALE PATTERN.  UNDER THE COOL
NWLY FLOW ALOFT...HIGHS WILL REMAIN A FEW DEGREES BELOW NORMAL INTO
THE WEEKEND WITH HIGHS AROUND 80F OR SO.  TIMING OF PERIODS OF PCPN
WILL BE LESS CERTAIN THAN THE TEMPERATURE TRENDS FOR THE NEXT FEW
DAYS AND WILL GENERALLY BE DEPENDENT ON THE TIMING OF SHORTWAVE
ENERGY DROPPING THROUGH THE NWLY FLOW ALOFT.  SO...WHILE NO DAY IN
THE SHORT TERM FORECAST PERIOD WILL BE A TOTAL WASHOUT...THERE
SHOULD BE PERIODS OF SCT SHRA AND ISOLD TSRA.

THE LONGER RANGE GUIDANCE IS IN GENERALLY GOOD AGREEMENT ON THE
UPPER LEVEL PATTERN BECOMING MORE PROGRESSIVE THROUGH THE WEEKEND.
THIS WILL INITIATE A WARMING TREND AS THE UPPER LEVEL RIDGING MOVES
OUT OVER THE WESTERN PLAINS ON SUNDAY WHILE THE UPPER LOW OVER JAMES
BAY KICKS OUT TO THE NORTHEAST...LEAVING WEAKER LONGWAVE TROUGHING
OVER THE ERN CONUS.  SUNDAY SHOULD BE A TRANSITIONAL DAY...WITH
INLAND TEMPS A LITTLE HIGHER...BUT A WEAK GRADIENT PERSISTING AT THE
SURFACE WILL ALLOW FOR ANOTHER LAKE BREEZE DAY AND COOLER CONDITIONS
NEAR THE LAKE. RISING HEIGHTS OVER THE MIDWEST SHOULD ALLOW FOR MAX
TEMPS TO CLIMB INTO THE MIDDLE 80S BY MONDAY.

MORE UNCERTAINTY WILL CREEP INTO THE FORECAST DURING THE EXTENDED
FORECAST PERIOD AS FLOW BECOMES MORE ZONAL OVER THE MIDWEST.  IN THE
INCREASINGLY ZONAL FLOW...SHORT WAVE STRENGTH AND TIMING WILL BECOME
MORE UNCERTAIN...SO...CONFIDENCE IN THE SENSIBLE WEATHER FORECAST
WILL INCREASE WITH TIME THROUGH THE EXTENDED FORECAST PERIOD.
HOWEVER...THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THE WARMING
TREND COULD BE BRIEF AS A WEAK UPPER LOW HANGS BACK OVER THE LOWER
MISSISSIPPI VALLEY THROUGH THE PERIOD AND THE UPPER RIDGING WILL NOT
BUILD ANY FARTHER EAST THAN THE CENTRAL PLAINS.  ALSO...THE SFC
PATTERN SHOULD REMAIN WEAK...SO DAILY LAKE BREEZE DEVELOPMENT WILL
BE LIKELY AS WELL. THE TREND FOR THE EXTEDNED FORECAST PERIOD IS
SHAPPING UP FOR MORE BELOW NORMAL TEMPERATURES WITH PERIODIC CHANCES
FOR AT LEAST SOME LIGHT PCPN.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* E-NE ARND 10 KT THE REST OF THE AFTERNOON.

* A FEW ISOLATED SHOWERS PSBL.

KJB

//DISCUSSION...UPDATED 18Z...

A LIGHT WIND FIELD ACROSS THE AREA IS ALLOWING A LAKE BREEZE TO
MAKE SOME GOOD PROGRESS INLAND ACROSS NORTHEASTERN ILLINOIS EARLY
THIS AFTERNOON. CURRENT TIMING LOOKS TO PUT THE BOUNDARY THROUGH
KMDW AROUND 1930 UTC AND THROUGH KORD IN THE 20 TO 21 UTC TIME
FRAME. WINDS DO NOT APPEAR TO BE OVERLY STRONG BEHIND THE LAKE
BREEZE...WITH GENERALLY ONLY AROUND 10 KT OF EAST-NORTHEASTERLY
FLOW EXPECTED. THE WINDS WILL GRADUALLY SHIFT BACK OUT OF THE
WEST-SOUTHWEST TONIGHT INTO THURSDAY. ANOTHER LAKE BREEZE MAY
DEVELOP ON THURSDAY. HOWEVER...WITH A SLIGHTLY STRONGER WEST-
SOUTHWESTERLY WIND FIELD EXPECTED ON THURSDAY...THE LAKE BREEZE
MAY STRUGGLE TO REACH THE TERMINALS.

THE OTHER CONCERN THIS AFTERNOON WILL...SIMILAR TO YESTERDAY...BE
THE THREAT FOR SOME WIDELY SCATTERED SHOWERS AND PERHAPS A
THUNDERSTORM ACROSS THE AREA. CUMULUS CLOUDS WILL LIKELY BE ON AN
UPTICK OVER THE NEXT HOUR OR SO AS TEMPERATURES CONTINUE TO WARM
THROUGH THE MID AND UPPER 70S. THIS CLOUD COVER COULD EVEN LEAD TO A
PERIOD OF LOWER END VFR CIG AROUND 4000 FEET AGL...ESPECIALLY AHEAD
OF THE LAKE BREEZE BOUNDARY. GIVEN THE LOWER AREAL COVERAGE
EXPECTED...I WILL CONTINUE WITH THE VCSH AND LEAVE THE MENTION OF
THUNDER OUT OF THE TAF AT THIS TIME.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM-HIGH WITH WINDS.

* LOW WITH A SHOWER OR TSRA IMPACTING THE TERMINAL THIS
  AFTERNOON/EVENING.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SCHC TSRA EARLY IN THE EVENING...SCHC SHRA LATE
IN THE EVENING.

FRIDAY...CHC SHRA WITH A CHC OF TSRA IN THE AFTN.

SATURDAY...SCHC SHRA IN THE MORNING...CHC OF TSRA IN THE AFTN.

SUNDAY...VFR.

MONDAY...CHC TSRA OVERNIGHT.

TUESDAY...CHC TSRA.

JEE

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 301955
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
255 PM CDT WED JUL 30 2014

.DISCUSSION...
254 PM CDT

A HIGH AMPLITUDE LONGWAVE PATTERN THAT HAS BEEN IN PLACE FOR THE
PAST FEW DAYS WILL PERSIST FOR THE NEXT FEW DAYS WITH DEEP LONG WAVE
TROUGHING OVER THE ERN CONUS AND AN UPPER LOW CENTER OVER JAMES
BAY...WITH RIDGING OVER THE WRN CONUS.  THE LOCAL AREA WILL REMAIN
UNDER GENERALLY NWLY FLOW ALOFT UNDER THE SWRN PERIPHERY OF THE
UPPER LOW.  THIS WILL ALLOW FOR A SERIES OF WEAK SHORT WAVES TO
RIPPLE THROUGH THE NWLY FLOW ALOFT OVER THE LOCAL AREA.

FOR THE REMAINDER OF THIS AFTERNOON AND THIS EVENING...THE MAIN
CONCERN WILL BE THE LAKE BREEZE BOUNDARY QUICKLY PUSHING INLAND
THROUGH NERN IL AND NWRN IN.  TEMPERATURES WILL DROP OFF SEVERAL
DEGREES WITH THE PASSAGE OF THE BOUNDARY AND LAKEFRONT LOCATIONS
HAVE ALREADY DROPPED INTO THE MIDDLE 60S.  THE ENVIRONMENT AHEAD OF
THE BOUNDARY IS MODESTLY MOIST AND UNSTABLE.  WITH CYCLONIC FLOW
ALOFT...DIURNAL CU HAS BEEN DEVELOPING OVER THE REGION PER THE LATEST
SATELLITE IMAGERY.  AS OF EARLY THIS AFTERNOON...HAVE NOT SEEN ANY
SHRA/TSRA ACTIVITY OVER NRN IL/NWRN IN...BUT THE REGION REMAINS
MODESTLY UNSTABLE WITH DEWPOINTS IN THE MIDDLE TO UPPER 50S.  THERE
WILL STILL BE A CHANCE FOR SOME SHRA/TSRA FOCUSED ALONG THE LAKE
BREEZE BOUNDARY AS WELL AS SOME ISOLD SHRA OR AN EVEN MORE ISOLD TS
OVER THE AREA THROUGH SUNSET.  DURG THE EVENING AND INTO THE
OVERNIGHT HOURS...ANY DIURNAL PCPN WILL DISSIPATE AND AND RESIDUAL
PCPN WILL BE WELL NORTH OF THE AREA INVOF ON OF THE SEEMINGLY
ENDLESS SERIES OF IMPULSES DROPPING THROUGH THE NORTHWEST FLOW.

LITTLE CHANGE IS EXPECTED FOR TOMORROW THROUGH SATURDAY AS THE
SYNOPTIC SCALE PATTERN SHOULD CHANGE LITTLE AND A WEAK GRADIENT
PATTERN WILL PERSIST AT THE SFC.  UNDER PERSISTENT NWLY FLOW
ALOFT...THE SERIES OF WEAK SHORTWAVES WILL CONTINUE TO BRING
PERIODIC CHANCES FOR SCT SHRA AND ISOLD TSRA...WITH THE BETTER
CHANCES FOR TS DURG THE AFTERNOON HOURS.  THE WEAK GRADIENT PATTERN
AT THE SFC SHOULD ALLOW FOR DAILY LAKE BREEZE DEVELOPMENT...WITH THE
MAIN QUESTION BEING HOW FAR INLAND A LAKE BREEZE WILL PENETRATE.
CERTAINLY...IT IS LIKELY THAT LAKEFRONT LOCATIONS WILL TURN COOLER
IN THE AFTERNOON...BUT IT IS LESS CERTAIN HOW FAR INLAND THE LAKE
COOLING WILL PENETRATE.  SO...WILL KEEP THE MAX TEMP FORECAST A BIT
ON THE CONSERVATIVE SIDE AS FAR AS LAKE INFLUENCE IS CONCERNED AND
LIMIT THE COOLING TO THE IMMEDIATE LAKEFRONT AND ALLOW MAX TEMPS TO
BE MORE REPRESENTATIVE OF THE LARGE SCALE PATTERN.  UNDER THE COOL
NWLY FLOW ALOFT...HIGHS WILL REMAIN A FEW DEGREES BELOW NORMAL INTO
THE WEEKEND WITH HIGHS AROUND 80F OR SO.  TIMING OF PERIODS OF PCPN
WILL BE LESS CERTAIN THAN THE TEMPERATURE TRENDS FOR THE NEXT FEW
DAYS AND WILL GENERALLY BE DEPENDENT ON THE TIMING OF SHORTWAVE
ENERGY DROPPING THROUGH THE NWLY FLOW ALOFT.  SO...WHILE NO DAY IN
THE SHORT TERM FORECAST PERIOD WILL BE A TOTAL WASHOUT...THERE
SHOULD BE PERIODS OF SCT SHRA AND ISOLD TSRA.

THE LONGER RANGE GUIDANCE IS IN GENERALLY GOOD AGREEMENT ON THE
UPPER LEVEL PATTERN BECOMING MORE PROGRESSIVE THROUGH THE WEEKEND.
THIS WILL INITIATE A WARMING TREND AS THE UPPER LEVEL RIDGING MOVES
OUT OVER THE WESTERN PLAINS ON SUNDAY WHILE THE UPPER LOW OVER JAMES
BAY KICKS OUT TO THE NORTHEAST...LEAVING WEAKER LONGWAVE TROUGHING
OVER THE ERN CONUS.  SUNDAY SHOULD BE A TRANSITIONAL DAY...WITH
INLAND TEMPS A LITTLE HIGHER...BUT A WEAK GRADIENT PERSISTING AT THE
SURFACE WILL ALLOW FOR ANOTHER LAKE BREEZE DAY AND COOLER CONDITIONS
NEAR THE LAKE. RISING HEIGHTS OVER THE MIDWEST SHOULD ALLOW FOR MAX
TEMPS TO CLIMB INTO THE MIDDLE 80S BY MONDAY.

MORE UNCERTAINTY WILL CREEP INTO THE FORECAST DURING THE EXTENDED
FORECAST PERIOD AS FLOW BECOMES MORE ZONAL OVER THE MIDWEST.  IN THE
INCREASINGLY ZONAL FLOW...SHORT WAVE STRENGTH AND TIMING WILL BECOME
MORE UNCERTAIN...SO...CONFIDENCE IN THE SENSIBLE WEATHER FORECAST
WILL INCREASE WITH TIME THROUGH THE EXTENDED FORECAST PERIOD.
HOWEVER...THE LATEST LONG RANGE GUIDANCE SUGGESTS THAT THE WARMING
TREND COULD BE BRIEF AS A WEAK UPPER LOW HANGS BACK OVER THE LOWER
MISSISSIPPI VALLEY THROUGH THE PERIOD AND THE UPPER RIDGING WILL NOT
BUILD ANY FARTHER EAST THAN THE CENTRAL PLAINS.  ALSO...THE SFC
PATTERN SHOULD REMAIN WEAK...SO DAILY LAKE BREEZE DEVELOPMENT WILL
BE LIKELY AS WELL. THE TREND FOR THE EXTEDNED FORECAST PERIOD IS
SHAPPING UP FOR MORE BELOW NORMAL TEMPERATURES WITH PERIODIC CHANCES
FOR AT LEAST SOME LIGHT PCPN.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* E-NE ARND 10 KT THE REST OF THE AFTERNOON.

* A FEW ISOLATED SHOWERS PSBL.

KJB

//DISCUSSION...UPDATED 18Z...

A LIGHT WIND FIELD ACROSS THE AREA IS ALLOWING A LAKE BREEZE TO
MAKE SOME GOOD PROGRESS INLAND ACROSS NORTHEASTERN ILLINOIS EARLY
THIS AFTERNOON. CURRENT TIMING LOOKS TO PUT THE BOUNDARY THROUGH
KMDW AROUND 1930 UTC AND THROUGH KORD IN THE 20 TO 21 UTC TIME
FRAME. WINDS DO NOT APPEAR TO BE OVERLY STRONG BEHIND THE LAKE
BREEZE...WITH GENERALLY ONLY AROUND 10 KT OF EAST-NORTHEASTERLY
FLOW EXPECTED. THE WINDS WILL GRADUALLY SHIFT BACK OUT OF THE
WEST-SOUTHWEST TONIGHT INTO THURSDAY. ANOTHER LAKE BREEZE MAY
DEVELOP ON THURSDAY. HOWEVER...WITH A SLIGHTLY STRONGER WEST-
SOUTHWESTERLY WIND FIELD EXPECTED ON THURSDAY...THE LAKE BREEZE
MAY STRUGGLE TO REACH THE TERMINALS.

THE OTHER CONCERN THIS AFTERNOON WILL...SIMILAR TO YESTERDAY...BE
THE THREAT FOR SOME WIDELY SCATTERED SHOWERS AND PERHAPS A
THUNDERSTORM ACROSS THE AREA. CUMULUS CLOUDS WILL LIKELY BE ON AN
UPTICK OVER THE NEXT HOUR OR SO AS TEMPERATURES CONTINUE TO WARM
THROUGH THE MID AND UPPER 70S. THIS CLOUD COVER COULD EVEN LEAD TO A
PERIOD OF LOWER END VFR CIG AROUND 4000 FEET AGL...ESPECIALLY AHEAD
OF THE LAKE BREEZE BOUNDARY. GIVEN THE LOWER AREAL COVERAGE
EXPECTED...I WILL CONTINUE WITH THE VCSH AND LEAVE THE MENTION OF
THUNDER OUT OF THE TAF AT THIS TIME.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM-HIGH WITH WINDS.

* LOW WITH A SHOWER OR TSRA IMPACTING THE TERMINAL THIS
  AFTERNOON/EVENING.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SCHC TSRA EARLY IN THE EVENING...SCHC SHRA LATE
IN THE EVENING.

FRIDAY...CHC SHRA WITH A CHC OF TSRA IN THE AFTN.

SATURDAY...SCHC SHRA IN THE MORNING...CHC OF TSRA IN THE AFTN.

SUNDAY...VFR.

MONDAY...CHC TSRA OVERNIGHT.

TUESDAY...CHC TSRA.

JEE

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 301952
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
252 PM CDT WED JUL 30 2014

.DISCUSSION...
315 AM CDT

SYNOPSIS...TODAY WILL BE VERY SIMILAR TO YESTERDAY WITH A LAKE
BREEZE PUSHING INLAND.  SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL FORM ALONG THE BOUNDARY. THERE ARE CHANCES FOR AFTERNOON
THUNDERSTORMS THROUGH SATURDAY WITH THE BETTER CHANCES FRIDAY AND
SATURDAY.  ADDITIONAL THUNDERSTORMS ARE POSSIBLE EARLY NEXT WEEK.
TEMPERATURES SLOWLY RISE THROUGH EARLY NEXT WEEK WITH MID 80 HIGH
TEMPS POSSIBLE MONDAY.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS STILL PARKED OVER JAMES BAY. A SHORT WAVE
TROUGH/COLD FRONT ASSOCIATED WITH THE LOW IS OVER CENTRAL WI AND IT
WILL SLIDE DOWN THE LAKE THROUGH THIS MORNING. THE FRONT LOSES STEAM
THIS AFTERNOON AND STALLS OVER NORTHERN IL AND IN.

A LAKE BREEZE IS ALSO EXPECTED TODAY SO THERE SHOULD BE ADEQUATE
FORCING FOR SHOWERS AND A FEW STORMS BETWEEN THE LAKE BREEZE AND
STALLED OUT COLD FRONT.  CAPE WILL ONCE AGAIN BE LIMITED TO BELOW
500 J/KG SO NOT EXPECTING A TON OF THUNDERSTORM ACTIVITY. UPPER
LEVEL TEMPS AND SURFACE TEMPS WILL BE A BIT COOLER TODAY SO THINKING
THAT WILL ALSO LIMIT INSTABILITY.  ANY STORMS THAT DO FORM WILL NOT
BE SEVERE...BUT MAY BE DOWNDRAFT DRIVEN PRODUCING GUSTY WINDS
LIKE YESTERDAY. HIGH TEMPS WILL BE IN THE UPPER 70S...EXCEPT ALONG
THE LAKE SHORE WHERE THE LAKE BREEZE WILL KEEP HIGH TEMPS IN THE
MID 70S.

SHOWERS AND STORMS DISSIPATE THIS EVENING WITH LIGHT SOUTHWEST WINDS
EXPECTED OVERNIGHT.  SKIES SHOULD CLEAR OUT NICELY SO EXPECTING MIN
TEMPS TO APPROACH THE DEWPOINTS. SO LOOKING AT LOWS IN THE UPPER 50S
IN THE OUTLYING AREAS...BUT IN THE LOW 60S DOWNTOWN.

JEE

THURSDAY THROUGH SATURDAY...

THE AREA REMAINS ON THE SOUTHWEST SIDE OF THE EASTERN CANADIAN
UPPER LONG WAVE TROUGH THROUGH THE END OF THE WEEK WITH LITTLE
CHANGE IN THE WEATHER PATTERN. AS IS TYPICALLY THE CASE WITH SUCH
AN ESTABLISHED LONG WAVE...MINOR PERTURBATIONS WILL TRAVERSE
DOWN THE BACK SIDE OF THE TROUGH OVER THE WESTERN GREAT
LAKES. EACH OF THESE LOOK TO BRING SUBTLE ENHANCEMENT TO LOW-
LEVEL CONVERGENCE AND KEEP COOL AIR ALOFT FOR ELONGATED CAPE
PROFILES NEAR PEAK HEATING. ALL IN ALL THESE CONTINUE TO PRESENT
MAINLY AFTERNOON AND EARLY EVENING SCATTERED SHOWER/STORM CHANCES.
THERE CONTINUES FAIR MODEL AGREEMENT ON BRINGING AN UPPER/MID
LEVEL SPEED MAX AND AN ASSOCIATED WAVE SOUTHWARD FOR BETTER
COVERAGE OF AFTERNOON SHOWERS/STORMS. BOTH THE SREF AND GEFS
SUPPORT HIGHER POPS OVER A GOOD AMOUNT OF THE AREA AND WHILE THE
MAGNITUDES OF BOTH MAY BE EXTREME /70 PERCENT PLUS/...THE IDEA OF
SCATTERED COVERAGE MORE SO THAN TODAY AND THURSDAY SEEMS LIKELY.
THE ASSOCIATED SURFACE FRONT HANGS UP OVER THE EASTERN FORECAST
AREA. THE LAKE BREEZE WILL CONTINUE TO ALSO BE A FOCUS FOR SHOWERS
AND STORMS...SO DO HAVE A LITTLE HIGHER POPS IN THE NORTHEAST
FORECAST AREA. VERY SLIGHT TEMPERATURE MODERATION IS EXPECTED
THROUGH THIS TIME.

EARLY NEXT WEEK...
HIGH PRESSURE LOOKS TO PREVAIL SATURDAY NIGHT THROUGH THE LATTER
HALF OF THE WEEKEND. THE UPPER LEVEL PATTERN LOOKS TO FLATTEN
SOMEWHAT WITH A QUICK MOVING SYSTEM NORTH OF THE GREAT LAKES
ADVERTISED EARLY NEXT WEEK BY GUIDANCE. THIS LOOKS TO STEER A COOL
FRONT INTO THE REGION WITH LARGE DISCREPANCY ON TIMING AND JUST
HOW FAR SOUTH THIS REACHES. HAVE NOT MADE ANY CHANGES TO A WELL-
VERIFYING BLEND OF GUIDANCE BESIDES INCHING UP TEMPS A COUPLE
DEGREES ON MONDAY AHEAD OF THIS COOL FRONTAL FEATURE.

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* E-NE ARND 10 KT THE REST OF THE AFTERNOON.

* A FEW ISOLATED SHOWERS PSBL.

KJB

//DISCUSSION...UPDATED 18Z...

A LIGHT WIND FIELD ACROSS THE AREA IS ALLOWING A LAKE BREEZE TO
MAKE SOME GOOD PROGRESS INLAND ACROSS NORTHEASTERN ILLINOIS EARLY
THIS AFTERNOON. CURRENT TIMING LOOKS TO PUT THE BOUNDARY THROUGH
KMDW AROUND 1930 UTC AND THROUGH KORD IN THE 20 TO 21 UTC TIME
FRAME. WINDS DO NOT APPEAR TO BE OVERLY STRONG BEHIND THE LAKE
BREEZE...WITH GENERALLY ONLY AROUND 10 KT OF EAST-NORTHEASTERLY
FLOW EXPECTED. THE WINDS WILL GRADUALLY SHIFT BACK OUT OF THE
WEST-SOUTHWEST TONIGHT INTO THURSDAY. ANOTHER LAKE BREEZE MAY
DEVELOP ON THURSDAY. HOWEVER...WITH A SLIGHTLY STRONGER WEST-
SOUTHWESTERLY WIND FIELD EXPECTED ON THURSDAY...THE LAKE BREEZE
MAY STRUGGLE TO REACH THE TERMINALS.

THE OTHER CONCERN THIS AFTERNOON WILL...SIMILAR TO YESTERDAY...BE
THE THREAT FOR SOME WIDELY SCATTERED SHOWERS AND PERHAPS A
THUNDERSTORM ACROSS THE AREA. CUMULUS CLOUDS WILL LIKELY BE ON AN
UPTICK OVER THE NEXT HOUR OR SO AS TEMPERATURES CONTINUE TO WARM
THROUGH THE MID AND UPPER 70S. THIS CLOUD COVER COULD EVEN LEAD TO A
PERIOD OF LOWER END VFR CIG AROUND 4000 FEET AGL...ESPECIALLY AHEAD
OF THE LAKE BREEZE BOUNDARY. GIVEN THE LOWER AREAL COVERAGE
EXPECTED...I WILL CONTINUE WITH THE VCSH AND LEAVE THE MENTION OF
THUNDER OUT OF THE TAF AT THIS TIME.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM-HIGH WITH WINDS.

* LOW WITH A SHOWER OR TSRA IMPACTING THE TERMINAL THIS
  AFTERNOON/EVENING.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SCHC TSRA EARLY IN THE EVENING...SCHC SHRA LATE
IN THE EVENING.

FRIDAY...CHC SHRA WITH A CHC OF TSRA IN THE AFTN.

SATURDAY...SCHC SHRA IN THE MORNING...CHC OF TSRA IN THE AFTN.

SUNDAY...VFR.

MONDAY...CHC TSRA OVERNIGHT.

TUESDAY...CHC TSRA.

JEE

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 301952
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
252 PM CDT WED JUL 30 2014

.DISCUSSION...
315 AM CDT

SYNOPSIS...TODAY WILL BE VERY SIMILAR TO YESTERDAY WITH A LAKE
BREEZE PUSHING INLAND.  SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL FORM ALONG THE BOUNDARY. THERE ARE CHANCES FOR AFTERNOON
THUNDERSTORMS THROUGH SATURDAY WITH THE BETTER CHANCES FRIDAY AND
SATURDAY.  ADDITIONAL THUNDERSTORMS ARE POSSIBLE EARLY NEXT WEEK.
TEMPERATURES SLOWLY RISE THROUGH EARLY NEXT WEEK WITH MID 80 HIGH
TEMPS POSSIBLE MONDAY.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS STILL PARKED OVER JAMES BAY. A SHORT WAVE
TROUGH/COLD FRONT ASSOCIATED WITH THE LOW IS OVER CENTRAL WI AND IT
WILL SLIDE DOWN THE LAKE THROUGH THIS MORNING. THE FRONT LOSES STEAM
THIS AFTERNOON AND STALLS OVER NORTHERN IL AND IN.

A LAKE BREEZE IS ALSO EXPECTED TODAY SO THERE SHOULD BE ADEQUATE
FORCING FOR SHOWERS AND A FEW STORMS BETWEEN THE LAKE BREEZE AND
STALLED OUT COLD FRONT.  CAPE WILL ONCE AGAIN BE LIMITED TO BELOW
500 J/KG SO NOT EXPECTING A TON OF THUNDERSTORM ACTIVITY. UPPER
LEVEL TEMPS AND SURFACE TEMPS WILL BE A BIT COOLER TODAY SO THINKING
THAT WILL ALSO LIMIT INSTABILITY.  ANY STORMS THAT DO FORM WILL NOT
BE SEVERE...BUT MAY BE DOWNDRAFT DRIVEN PRODUCING GUSTY WINDS
LIKE YESTERDAY. HIGH TEMPS WILL BE IN THE UPPER 70S...EXCEPT ALONG
THE LAKE SHORE WHERE THE LAKE BREEZE WILL KEEP HIGH TEMPS IN THE
MID 70S.

SHOWERS AND STORMS DISSIPATE THIS EVENING WITH LIGHT SOUTHWEST WINDS
EXPECTED OVERNIGHT.  SKIES SHOULD CLEAR OUT NICELY SO EXPECTING MIN
TEMPS TO APPROACH THE DEWPOINTS. SO LOOKING AT LOWS IN THE UPPER 50S
IN THE OUTLYING AREAS...BUT IN THE LOW 60S DOWNTOWN.

JEE

THURSDAY THROUGH SATURDAY...

THE AREA REMAINS ON THE SOUTHWEST SIDE OF THE EASTERN CANADIAN
UPPER LONG WAVE TROUGH THROUGH THE END OF THE WEEK WITH LITTLE
CHANGE IN THE WEATHER PATTERN. AS IS TYPICALLY THE CASE WITH SUCH
AN ESTABLISHED LONG WAVE...MINOR PERTURBATIONS WILL TRAVERSE
DOWN THE BACK SIDE OF THE TROUGH OVER THE WESTERN GREAT
LAKES. EACH OF THESE LOOK TO BRING SUBTLE ENHANCEMENT TO LOW-
LEVEL CONVERGENCE AND KEEP COOL AIR ALOFT FOR ELONGATED CAPE
PROFILES NEAR PEAK HEATING. ALL IN ALL THESE CONTINUE TO PRESENT
MAINLY AFTERNOON AND EARLY EVENING SCATTERED SHOWER/STORM CHANCES.
THERE CONTINUES FAIR MODEL AGREEMENT ON BRINGING AN UPPER/MID
LEVEL SPEED MAX AND AN ASSOCIATED WAVE SOUTHWARD FOR BETTER
COVERAGE OF AFTERNOON SHOWERS/STORMS. BOTH THE SREF AND GEFS
SUPPORT HIGHER POPS OVER A GOOD AMOUNT OF THE AREA AND WHILE THE
MAGNITUDES OF BOTH MAY BE EXTREME /70 PERCENT PLUS/...THE IDEA OF
SCATTERED COVERAGE MORE SO THAN TODAY AND THURSDAY SEEMS LIKELY.
THE ASSOCIATED SURFACE FRONT HANGS UP OVER THE EASTERN FORECAST
AREA. THE LAKE BREEZE WILL CONTINUE TO ALSO BE A FOCUS FOR SHOWERS
AND STORMS...SO DO HAVE A LITTLE HIGHER POPS IN THE NORTHEAST
FORECAST AREA. VERY SLIGHT TEMPERATURE MODERATION IS EXPECTED
THROUGH THIS TIME.

EARLY NEXT WEEK...
HIGH PRESSURE LOOKS TO PREVAIL SATURDAY NIGHT THROUGH THE LATTER
HALF OF THE WEEKEND. THE UPPER LEVEL PATTERN LOOKS TO FLATTEN
SOMEWHAT WITH A QUICK MOVING SYSTEM NORTH OF THE GREAT LAKES
ADVERTISED EARLY NEXT WEEK BY GUIDANCE. THIS LOOKS TO STEER A COOL
FRONT INTO THE REGION WITH LARGE DISCREPANCY ON TIMING AND JUST
HOW FAR SOUTH THIS REACHES. HAVE NOT MADE ANY CHANGES TO A WELL-
VERIFYING BLEND OF GUIDANCE BESIDES INCHING UP TEMPS A COUPLE
DEGREES ON MONDAY AHEAD OF THIS COOL FRONTAL FEATURE.

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* E-NE ARND 10 KT THE REST OF THE AFTERNOON.

* A FEW ISOLATED SHOWERS PSBL.

KJB

//DISCUSSION...UPDATED 18Z...

A LIGHT WIND FIELD ACROSS THE AREA IS ALLOWING A LAKE BREEZE TO
MAKE SOME GOOD PROGRESS INLAND ACROSS NORTHEASTERN ILLINOIS EARLY
THIS AFTERNOON. CURRENT TIMING LOOKS TO PUT THE BOUNDARY THROUGH
KMDW AROUND 1930 UTC AND THROUGH KORD IN THE 20 TO 21 UTC TIME
FRAME. WINDS DO NOT APPEAR TO BE OVERLY STRONG BEHIND THE LAKE
BREEZE...WITH GENERALLY ONLY AROUND 10 KT OF EAST-NORTHEASTERLY
FLOW EXPECTED. THE WINDS WILL GRADUALLY SHIFT BACK OUT OF THE
WEST-SOUTHWEST TONIGHT INTO THURSDAY. ANOTHER LAKE BREEZE MAY
DEVELOP ON THURSDAY. HOWEVER...WITH A SLIGHTLY STRONGER WEST-
SOUTHWESTERLY WIND FIELD EXPECTED ON THURSDAY...THE LAKE BREEZE
MAY STRUGGLE TO REACH THE TERMINALS.

THE OTHER CONCERN THIS AFTERNOON WILL...SIMILAR TO YESTERDAY...BE
THE THREAT FOR SOME WIDELY SCATTERED SHOWERS AND PERHAPS A
THUNDERSTORM ACROSS THE AREA. CUMULUS CLOUDS WILL LIKELY BE ON AN
UPTICK OVER THE NEXT HOUR OR SO AS TEMPERATURES CONTINUE TO WARM
THROUGH THE MID AND UPPER 70S. THIS CLOUD COVER COULD EVEN LEAD TO A
PERIOD OF LOWER END VFR CIG AROUND 4000 FEET AGL...ESPECIALLY AHEAD
OF THE LAKE BREEZE BOUNDARY. GIVEN THE LOWER AREAL COVERAGE
EXPECTED...I WILL CONTINUE WITH THE VCSH AND LEAVE THE MENTION OF
THUNDER OUT OF THE TAF AT THIS TIME.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM-HIGH WITH WINDS.

* LOW WITH A SHOWER OR TSRA IMPACTING THE TERMINAL THIS
  AFTERNOON/EVENING.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SCHC TSRA EARLY IN THE EVENING...SCHC SHRA LATE
IN THE EVENING.

FRIDAY...CHC SHRA WITH A CHC OF TSRA IN THE AFTN.

SATURDAY...SCHC SHRA IN THE MORNING...CHC OF TSRA IN THE AFTN.

SUNDAY...VFR.

MONDAY...CHC TSRA OVERNIGHT.

TUESDAY...CHC TSRA.

JEE

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 301952
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
252 PM CDT WED JUL 30 2014

.DISCUSSION...
315 AM CDT

SYNOPSIS...TODAY WILL BE VERY SIMILAR TO YESTERDAY WITH A LAKE
BREEZE PUSHING INLAND.  SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL FORM ALONG THE BOUNDARY. THERE ARE CHANCES FOR AFTERNOON
THUNDERSTORMS THROUGH SATURDAY WITH THE BETTER CHANCES FRIDAY AND
SATURDAY.  ADDITIONAL THUNDERSTORMS ARE POSSIBLE EARLY NEXT WEEK.
TEMPERATURES SLOWLY RISE THROUGH EARLY NEXT WEEK WITH MID 80 HIGH
TEMPS POSSIBLE MONDAY.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS STILL PARKED OVER JAMES BAY. A SHORT WAVE
TROUGH/COLD FRONT ASSOCIATED WITH THE LOW IS OVER CENTRAL WI AND IT
WILL SLIDE DOWN THE LAKE THROUGH THIS MORNING. THE FRONT LOSES STEAM
THIS AFTERNOON AND STALLS OVER NORTHERN IL AND IN.

A LAKE BREEZE IS ALSO EXPECTED TODAY SO THERE SHOULD BE ADEQUATE
FORCING FOR SHOWERS AND A FEW STORMS BETWEEN THE LAKE BREEZE AND
STALLED OUT COLD FRONT.  CAPE WILL ONCE AGAIN BE LIMITED TO BELOW
500 J/KG SO NOT EXPECTING A TON OF THUNDERSTORM ACTIVITY. UPPER
LEVEL TEMPS AND SURFACE TEMPS WILL BE A BIT COOLER TODAY SO THINKING
THAT WILL ALSO LIMIT INSTABILITY.  ANY STORMS THAT DO FORM WILL NOT
BE SEVERE...BUT MAY BE DOWNDRAFT DRIVEN PRODUCING GUSTY WINDS
LIKE YESTERDAY. HIGH TEMPS WILL BE IN THE UPPER 70S...EXCEPT ALONG
THE LAKE SHORE WHERE THE LAKE BREEZE WILL KEEP HIGH TEMPS IN THE
MID 70S.

SHOWERS AND STORMS DISSIPATE THIS EVENING WITH LIGHT SOUTHWEST WINDS
EXPECTED OVERNIGHT.  SKIES SHOULD CLEAR OUT NICELY SO EXPECTING MIN
TEMPS TO APPROACH THE DEWPOINTS. SO LOOKING AT LOWS IN THE UPPER 50S
IN THE OUTLYING AREAS...BUT IN THE LOW 60S DOWNTOWN.

JEE

THURSDAY THROUGH SATURDAY...

THE AREA REMAINS ON THE SOUTHWEST SIDE OF THE EASTERN CANADIAN
UPPER LONG WAVE TROUGH THROUGH THE END OF THE WEEK WITH LITTLE
CHANGE IN THE WEATHER PATTERN. AS IS TYPICALLY THE CASE WITH SUCH
AN ESTABLISHED LONG WAVE...MINOR PERTURBATIONS WILL TRAVERSE
DOWN THE BACK SIDE OF THE TROUGH OVER THE WESTERN GREAT
LAKES. EACH OF THESE LOOK TO BRING SUBTLE ENHANCEMENT TO LOW-
LEVEL CONVERGENCE AND KEEP COOL AIR ALOFT FOR ELONGATED CAPE
PROFILES NEAR PEAK HEATING. ALL IN ALL THESE CONTINUE TO PRESENT
MAINLY AFTERNOON AND EARLY EVENING SCATTERED SHOWER/STORM CHANCES.
THERE CONTINUES FAIR MODEL AGREEMENT ON BRINGING AN UPPER/MID
LEVEL SPEED MAX AND AN ASSOCIATED WAVE SOUTHWARD FOR BETTER
COVERAGE OF AFTERNOON SHOWERS/STORMS. BOTH THE SREF AND GEFS
SUPPORT HIGHER POPS OVER A GOOD AMOUNT OF THE AREA AND WHILE THE
MAGNITUDES OF BOTH MAY BE EXTREME /70 PERCENT PLUS/...THE IDEA OF
SCATTERED COVERAGE MORE SO THAN TODAY AND THURSDAY SEEMS LIKELY.
THE ASSOCIATED SURFACE FRONT HANGS UP OVER THE EASTERN FORECAST
AREA. THE LAKE BREEZE WILL CONTINUE TO ALSO BE A FOCUS FOR SHOWERS
AND STORMS...SO DO HAVE A LITTLE HIGHER POPS IN THE NORTHEAST
FORECAST AREA. VERY SLIGHT TEMPERATURE MODERATION IS EXPECTED
THROUGH THIS TIME.

EARLY NEXT WEEK...
HIGH PRESSURE LOOKS TO PREVAIL SATURDAY NIGHT THROUGH THE LATTER
HALF OF THE WEEKEND. THE UPPER LEVEL PATTERN LOOKS TO FLATTEN
SOMEWHAT WITH A QUICK MOVING SYSTEM NORTH OF THE GREAT LAKES
ADVERTISED EARLY NEXT WEEK BY GUIDANCE. THIS LOOKS TO STEER A COOL
FRONT INTO THE REGION WITH LARGE DISCREPANCY ON TIMING AND JUST
HOW FAR SOUTH THIS REACHES. HAVE NOT MADE ANY CHANGES TO A WELL-
VERIFYING BLEND OF GUIDANCE BESIDES INCHING UP TEMPS A COUPLE
DEGREES ON MONDAY AHEAD OF THIS COOL FRONTAL FEATURE.

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* E-NE ARND 10 KT THE REST OF THE AFTERNOON.

* A FEW ISOLATED SHOWERS PSBL.

KJB

//DISCUSSION...UPDATED 18Z...

A LIGHT WIND FIELD ACROSS THE AREA IS ALLOWING A LAKE BREEZE TO
MAKE SOME GOOD PROGRESS INLAND ACROSS NORTHEASTERN ILLINOIS EARLY
THIS AFTERNOON. CURRENT TIMING LOOKS TO PUT THE BOUNDARY THROUGH
KMDW AROUND 1930 UTC AND THROUGH KORD IN THE 20 TO 21 UTC TIME
FRAME. WINDS DO NOT APPEAR TO BE OVERLY STRONG BEHIND THE LAKE
BREEZE...WITH GENERALLY ONLY AROUND 10 KT OF EAST-NORTHEASTERLY
FLOW EXPECTED. THE WINDS WILL GRADUALLY SHIFT BACK OUT OF THE
WEST-SOUTHWEST TONIGHT INTO THURSDAY. ANOTHER LAKE BREEZE MAY
DEVELOP ON THURSDAY. HOWEVER...WITH A SLIGHTLY STRONGER WEST-
SOUTHWESTERLY WIND FIELD EXPECTED ON THURSDAY...THE LAKE BREEZE
MAY STRUGGLE TO REACH THE TERMINALS.

THE OTHER CONCERN THIS AFTERNOON WILL...SIMILAR TO YESTERDAY...BE
THE THREAT FOR SOME WIDELY SCATTERED SHOWERS AND PERHAPS A
THUNDERSTORM ACROSS THE AREA. CUMULUS CLOUDS WILL LIKELY BE ON AN
UPTICK OVER THE NEXT HOUR OR SO AS TEMPERATURES CONTINUE TO WARM
THROUGH THE MID AND UPPER 70S. THIS CLOUD COVER COULD EVEN LEAD TO A
PERIOD OF LOWER END VFR CIG AROUND 4000 FEET AGL...ESPECIALLY AHEAD
OF THE LAKE BREEZE BOUNDARY. GIVEN THE LOWER AREAL COVERAGE
EXPECTED...I WILL CONTINUE WITH THE VCSH AND LEAVE THE MENTION OF
THUNDER OUT OF THE TAF AT THIS TIME.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM-HIGH WITH WINDS.

* LOW WITH A SHOWER OR TSRA IMPACTING THE TERMINAL THIS
  AFTERNOON/EVENING.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SCHC TSRA EARLY IN THE EVENING...SCHC SHRA LATE
IN THE EVENING.

FRIDAY...CHC SHRA WITH A CHC OF TSRA IN THE AFTN.

SATURDAY...SCHC SHRA IN THE MORNING...CHC OF TSRA IN THE AFTN.

SUNDAY...VFR.

MONDAY...CHC TSRA OVERNIGHT.

TUESDAY...CHC TSRA.

JEE

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 301952
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
252 PM CDT WED JUL 30 2014

.DISCUSSION...
315 AM CDT

SYNOPSIS...TODAY WILL BE VERY SIMILAR TO YESTERDAY WITH A LAKE
BREEZE PUSHING INLAND.  SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL FORM ALONG THE BOUNDARY. THERE ARE CHANCES FOR AFTERNOON
THUNDERSTORMS THROUGH SATURDAY WITH THE BETTER CHANCES FRIDAY AND
SATURDAY.  ADDITIONAL THUNDERSTORMS ARE POSSIBLE EARLY NEXT WEEK.
TEMPERATURES SLOWLY RISE THROUGH EARLY NEXT WEEK WITH MID 80 HIGH
TEMPS POSSIBLE MONDAY.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS STILL PARKED OVER JAMES BAY. A SHORT WAVE
TROUGH/COLD FRONT ASSOCIATED WITH THE LOW IS OVER CENTRAL WI AND IT
WILL SLIDE DOWN THE LAKE THROUGH THIS MORNING. THE FRONT LOSES STEAM
THIS AFTERNOON AND STALLS OVER NORTHERN IL AND IN.

A LAKE BREEZE IS ALSO EXPECTED TODAY SO THERE SHOULD BE ADEQUATE
FORCING FOR SHOWERS AND A FEW STORMS BETWEEN THE LAKE BREEZE AND
STALLED OUT COLD FRONT.  CAPE WILL ONCE AGAIN BE LIMITED TO BELOW
500 J/KG SO NOT EXPECTING A TON OF THUNDERSTORM ACTIVITY. UPPER
LEVEL TEMPS AND SURFACE TEMPS WILL BE A BIT COOLER TODAY SO THINKING
THAT WILL ALSO LIMIT INSTABILITY.  ANY STORMS THAT DO FORM WILL NOT
BE SEVERE...BUT MAY BE DOWNDRAFT DRIVEN PRODUCING GUSTY WINDS
LIKE YESTERDAY. HIGH TEMPS WILL BE IN THE UPPER 70S...EXCEPT ALONG
THE LAKE SHORE WHERE THE LAKE BREEZE WILL KEEP HIGH TEMPS IN THE
MID 70S.

SHOWERS AND STORMS DISSIPATE THIS EVENING WITH LIGHT SOUTHWEST WINDS
EXPECTED OVERNIGHT.  SKIES SHOULD CLEAR OUT NICELY SO EXPECTING MIN
TEMPS TO APPROACH THE DEWPOINTS. SO LOOKING AT LOWS IN THE UPPER 50S
IN THE OUTLYING AREAS...BUT IN THE LOW 60S DOWNTOWN.

JEE

THURSDAY THROUGH SATURDAY...

THE AREA REMAINS ON THE SOUTHWEST SIDE OF THE EASTERN CANADIAN
UPPER LONG WAVE TROUGH THROUGH THE END OF THE WEEK WITH LITTLE
CHANGE IN THE WEATHER PATTERN. AS IS TYPICALLY THE CASE WITH SUCH
AN ESTABLISHED LONG WAVE...MINOR PERTURBATIONS WILL TRAVERSE
DOWN THE BACK SIDE OF THE TROUGH OVER THE WESTERN GREAT
LAKES. EACH OF THESE LOOK TO BRING SUBTLE ENHANCEMENT TO LOW-
LEVEL CONVERGENCE AND KEEP COOL AIR ALOFT FOR ELONGATED CAPE
PROFILES NEAR PEAK HEATING. ALL IN ALL THESE CONTINUE TO PRESENT
MAINLY AFTERNOON AND EARLY EVENING SCATTERED SHOWER/STORM CHANCES.
THERE CONTINUES FAIR MODEL AGREEMENT ON BRINGING AN UPPER/MID
LEVEL SPEED MAX AND AN ASSOCIATED WAVE SOUTHWARD FOR BETTER
COVERAGE OF AFTERNOON SHOWERS/STORMS. BOTH THE SREF AND GEFS
SUPPORT HIGHER POPS OVER A GOOD AMOUNT OF THE AREA AND WHILE THE
MAGNITUDES OF BOTH MAY BE EXTREME /70 PERCENT PLUS/...THE IDEA OF
SCATTERED COVERAGE MORE SO THAN TODAY AND THURSDAY SEEMS LIKELY.
THE ASSOCIATED SURFACE FRONT HANGS UP OVER THE EASTERN FORECAST
AREA. THE LAKE BREEZE WILL CONTINUE TO ALSO BE A FOCUS FOR SHOWERS
AND STORMS...SO DO HAVE A LITTLE HIGHER POPS IN THE NORTHEAST
FORECAST AREA. VERY SLIGHT TEMPERATURE MODERATION IS EXPECTED
THROUGH THIS TIME.

EARLY NEXT WEEK...
HIGH PRESSURE LOOKS TO PREVAIL SATURDAY NIGHT THROUGH THE LATTER
HALF OF THE WEEKEND. THE UPPER LEVEL PATTERN LOOKS TO FLATTEN
SOMEWHAT WITH A QUICK MOVING SYSTEM NORTH OF THE GREAT LAKES
ADVERTISED EARLY NEXT WEEK BY GUIDANCE. THIS LOOKS TO STEER A COOL
FRONT INTO THE REGION WITH LARGE DISCREPANCY ON TIMING AND JUST
HOW FAR SOUTH THIS REACHES. HAVE NOT MADE ANY CHANGES TO A WELL-
VERIFYING BLEND OF GUIDANCE BESIDES INCHING UP TEMPS A COUPLE
DEGREES ON MONDAY AHEAD OF THIS COOL FRONTAL FEATURE.

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* E-NE ARND 10 KT THE REST OF THE AFTERNOON.

* A FEW ISOLATED SHOWERS PSBL.

KJB

//DISCUSSION...UPDATED 18Z...

A LIGHT WIND FIELD ACROSS THE AREA IS ALLOWING A LAKE BREEZE TO
MAKE SOME GOOD PROGRESS INLAND ACROSS NORTHEASTERN ILLINOIS EARLY
THIS AFTERNOON. CURRENT TIMING LOOKS TO PUT THE BOUNDARY THROUGH
KMDW AROUND 1930 UTC AND THROUGH KORD IN THE 20 TO 21 UTC TIME
FRAME. WINDS DO NOT APPEAR TO BE OVERLY STRONG BEHIND THE LAKE
BREEZE...WITH GENERALLY ONLY AROUND 10 KT OF EAST-NORTHEASTERLY
FLOW EXPECTED. THE WINDS WILL GRADUALLY SHIFT BACK OUT OF THE
WEST-SOUTHWEST TONIGHT INTO THURSDAY. ANOTHER LAKE BREEZE MAY
DEVELOP ON THURSDAY. HOWEVER...WITH A SLIGHTLY STRONGER WEST-
SOUTHWESTERLY WIND FIELD EXPECTED ON THURSDAY...THE LAKE BREEZE
MAY STRUGGLE TO REACH THE TERMINALS.

THE OTHER CONCERN THIS AFTERNOON WILL...SIMILAR TO YESTERDAY...BE
THE THREAT FOR SOME WIDELY SCATTERED SHOWERS AND PERHAPS A
THUNDERSTORM ACROSS THE AREA. CUMULUS CLOUDS WILL LIKELY BE ON AN
UPTICK OVER THE NEXT HOUR OR SO AS TEMPERATURES CONTINUE TO WARM
THROUGH THE MID AND UPPER 70S. THIS CLOUD COVER COULD EVEN LEAD TO A
PERIOD OF LOWER END VFR CIG AROUND 4000 FEET AGL...ESPECIALLY AHEAD
OF THE LAKE BREEZE BOUNDARY. GIVEN THE LOWER AREAL COVERAGE
EXPECTED...I WILL CONTINUE WITH THE VCSH AND LEAVE THE MENTION OF
THUNDER OUT OF THE TAF AT THIS TIME.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* MEDIUM-HIGH WITH WINDS.

* LOW WITH A SHOWER OR TSRA IMPACTING THE TERMINAL THIS
  AFTERNOON/EVENING.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SCHC TSRA EARLY IN THE EVENING...SCHC SHRA LATE
IN THE EVENING.

FRIDAY...CHC SHRA WITH A CHC OF TSRA IN THE AFTN.

SATURDAY...SCHC SHRA IN THE MORNING...CHC OF TSRA IN THE AFTN.

SUNDAY...VFR.

MONDAY...CHC TSRA OVERNIGHT.

TUESDAY...CHC TSRA.

JEE

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 301902
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
202 PM CDT WED JUL 30 2014

.DISCUSSION...
315 AM CDT

SYNOPSIS...TODAY WILL BE VERY SIMILAR TO YESTERDAY WITH A LAKE
BREEZE PUSHING INLAND.  SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL FORM ALONG THE BOUNDARY. THERE ARE CHANCES FOR AFTERNOON
THUNDERSTORMS THROUGH SATURDAY WITH THE BETTER CHANCES FRIDAY AND
SATURDAY.  ADDITIONAL THUNDERSTORMS ARE POSSIBLE EARLY NEXT WEEK.
TEMPERATURES SLOWLY RISE THROUGH EARLY NEXT WEEK WITH MID 80 HIGH
TEMPS POSSIBLE MONDAY.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS STILL PARKED OVER JAMES BAY. A SHORT WAVE
TROUGH/COLD FRONT ASSOCIATED WITH THE LOW IS OVER CENTRAL WI AND IT
WILL SLIDE DOWN THE LAKE THROUGH THIS MORNING. THE FRONT LOSES STEAM
THIS AFTERNOON AND STALLS OVER NORTHERN IL AND IN.

A LAKE BREEZE IS ALSO EXPECTED TODAY SO THERE SHOULD BE ADEQUATE
FORCING FOR SHOWERS AND A FEW STORMS BETWEEN THE LAKE BREEZE AND
STALLED OUT COLD FRONT.  CAPE WILL ONCE AGAIN BE LIMITED TO BELOW
500 J/KG SO NOT EXPECTING A TON OF THUNDERSTORM ACTIVITY. UPPER
LEVEL TEMPS AND SURFACE TEMPS WILL BE A BIT COOLER TODAY SO THINKING
THAT WILL ALSO LIMIT INSTABILITY.  ANY STORMS THAT DO FORM WILL NOT
BE SEVERE...BUT MAY BE DOWNDRAFT DRIVEN PRODUCING GUSTY WINDS
LIKE YESTERDAY. HIGH TEMPS WILL BE IN THE UPPER 70S...EXCEPT ALONG
THE LAKE SHORE WHERE THE LAKE BREEZE WILL KEEP HIGH TEMPS IN THE
MID 70S.

SHOWERS AND STORMS DISSIPATE THIS EVENING WITH LIGHT SOUTHWEST WINDS
EXPECTED OVERNIGHT.  SKIES SHOULD CLEAR OUT NICELY SO EXPECTING MIN
TEMPS TO APPROACH THE DEWPOINTS. SO LOOKING AT LOWS IN THE UPPER 50S
IN THE OUTLYING AREAS...BUT IN THE LOW 60S DOWNTOWN.

JEE

THURSDAY THROUGH SATURDAY...

THE AREA REMAINS ON THE SOUTHWEST SIDE OF THE EASTERN CANADIAN
UPPER LONG WAVE TROUGH THROUGH THE END OF THE WEEK WITH LITTLE
CHANGE IN THE WEATHER PATTERN. AS IS TYPICALLY THE CASE WITH SUCH
AN ESTABLISHED LONG WAVE...MINOR PERTURBATIONS WILL TRAVERSE
DOWN THE BACK SIDE OF THE TROUGH OVER THE WESTERN GREAT
LAKES. EACH OF THESE LOOK TO BRING SUBTLE ENHANCEMENT TO LOW-
LEVEL CONVERGENCE AND KEEP COOL AIR ALOFT FOR ELONGATED CAPE
PROFILES NEAR PEAK HEATING. ALL IN ALL THESE CONTINUE TO PRESENT
MAINLY AFTERNOON AND EARLY EVENING SCATTERED SHOWER/STORM CHANCES.
THERE CONTINUES FAIR MODEL AGREEMENT ON BRINGING AN UPPER/MID
LEVEL SPEED MAX AND AN ASSOCIATED WAVE SOUTHWARD FOR BETTER
COVERAGE OF AFTERNOON SHOWERS/STORMS. BOTH THE SREF AND GEFS
SUPPORT HIGHER POPS OVER A GOOD AMOUNT OF THE AREA AND WHILE THE
MAGNITUDES OF BOTH MAY BE EXTREME /70 PERCENT PLUS/...THE IDEA OF
SCATTERED COVERAGE MORE SO THAN TODAY AND THURSDAY SEEMS LIKELY.
THE ASSOCIATED SURFACE FRONT HANGS UP OVER THE EASTERN FORECAST
AREA. THE LAKE BREEZE WILL CONTINUE TO ALSO BE A FOCUS FOR SHOWERS
AND STORMS...SO DO HAVE A LITTLE HIGHER POPS IN THE NORTHEAST
FORECAST AREA. VERY SLIGHT TEMPERATURE MODERATION IS EXPECTED
THROUGH THIS TIME.

EARLY NEXT WEEK...
HIGH PRESSURE LOOKS TO PREVAIL SATURDAY NIGHT THROUGH THE LATTER
HALF OF THE WEEKEND. THE UPPER LEVEL PATTERN LOOKS TO FLATTEN
SOMEWHAT WITH A QUICK MOVING SYSTEM NORTH OF THE GREAT LAKES
ADVERTISED EARLY NEXT WEEK BY GUIDANCE. THIS LOOKS TO STEER A COOL
FRONT INTO THE REGION WITH LARGE DISCREPANCY ON TIMING AND JUST
HOW FAR SOUTH THIS REACHES. HAVE NOT MADE ANY CHANGES TO A WELL-
VERIFYING BLEND OF GUIDANCE BESIDES INCHING UP TEMPS A COUPLE
DEGREES ON MONDAY AHEAD OF THIS COOL FRONTAL FEATURE.

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* LAKE BREEZE EXPECTED WITH WINDS SHIFTING E-NE ARND 10
  KT...THROUGH MDW AROUND 1930 UTC AND ORD BETWEEN 20 AND 21 UTC.

* WIDELY SCT SHRA THIS AFTN AND EARLY EVENING. A FEW TSRA ALSO
  PSBL.

KJB

//DISCUSSION...UPDATED 18Z...

A LIGHT WIND FIELD ACROSS THE AREA IS ALLOWING A LAKE BREEZE TO
MAKE SOME GOOD PROGRESS INLAND ACROSS NORTHEASTERN ILLINOIS EARLY
THIS AFTERNOON. CURRENT TIMING LOOKS TO PUT THE BOUNDARY THROUGH
KMDW AROUND 1930 UTC AND THROUGH KORD IN THE 20 TO 21 UTC TIME
FRAME. WINDS DO NOT APPEAR TO BE OVERLY STRONG BEHIND THE LAKE
BREEZE...WITH GENERALLY ONLY AROUND 10 KT OF EAST-NORTHEASTERLY
FLOW EXPECTED. THE WINDS WILL GRADUALLY SHIFT BACK OUT OF THE
WEST-SOUTHWEST TONIGHT INTO THURSDAY. ANOTHER LAKE BREEZE MAY
DEVELOP ON THURSDAY. HOWEVER...WITH A SLIGHTLY STRONGER WEST-
SOUTHWESTERLY WIND FIELD EXPECTED ON THURSDAY...THE LAKE BREEZE
MAY STRUGGLE TO REACH THE TERMINALS.

THE OTHER CONCERN THIS AFTERNOON WILL...SIMILAR TO YESTERDAY...BE
THE THREAT FOR SOME WIDELY SCATTERED SHOWERS AND PERHAPS A
THUNDERSTORM ACROSS THE AREA. CUMULUS CLOUDS WILL LIKELY BE ON AN
UPTICK OVER THE NEXT HOUR OR SO AS TEMPERATURES CONTINUE TO WARM
THROUGH THE MID AND UPPER 70S. THIS CLOUD COVER COULD EVEN LEAD TO A
PERIOD OF LOWER END VFR CIG AROUND 4000 FEET AGL...ESPECIALLY AHEAD
OF THE LAKE BREEZE BOUNDARY. GIVEN THE LOWER AREAL COVERAGE
EXPECTED...I WILL CONTINUE WITH THE VCSH AND LEAVE THE MENTION OF
THUNDER OUT OF THE TAF AT THIS TIME.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM-HIGH WITH LAKE BREEZE TIMING.

* MEDIUM-HIGH IN ISOLATED TO SCT -SHRA ACROSS THE REGION...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SCHC TSRA EARLY IN THE EVENING...SCHC SHRA LATE
IN THE EVENING.

FRIDAY...CHC SHRA WITH A CHC OF TSRA IN THE AFTN.

SATURDAY...SCHC SHRA IN THE MORNING...CHC OF TSRA IN THE AFTN.

SUNDAY...VFR.

MONDAY...CHC TSRA OVERNIGHT.

TUESDAY...CHC TSRA.

JEE

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 301902
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
202 PM CDT WED JUL 30 2014

.DISCUSSION...
315 AM CDT

SYNOPSIS...TODAY WILL BE VERY SIMILAR TO YESTERDAY WITH A LAKE
BREEZE PUSHING INLAND.  SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL FORM ALONG THE BOUNDARY. THERE ARE CHANCES FOR AFTERNOON
THUNDERSTORMS THROUGH SATURDAY WITH THE BETTER CHANCES FRIDAY AND
SATURDAY.  ADDITIONAL THUNDERSTORMS ARE POSSIBLE EARLY NEXT WEEK.
TEMPERATURES SLOWLY RISE THROUGH EARLY NEXT WEEK WITH MID 80 HIGH
TEMPS POSSIBLE MONDAY.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS STILL PARKED OVER JAMES BAY. A SHORT WAVE
TROUGH/COLD FRONT ASSOCIATED WITH THE LOW IS OVER CENTRAL WI AND IT
WILL SLIDE DOWN THE LAKE THROUGH THIS MORNING. THE FRONT LOSES STEAM
THIS AFTERNOON AND STALLS OVER NORTHERN IL AND IN.

A LAKE BREEZE IS ALSO EXPECTED TODAY SO THERE SHOULD BE ADEQUATE
FORCING FOR SHOWERS AND A FEW STORMS BETWEEN THE LAKE BREEZE AND
STALLED OUT COLD FRONT.  CAPE WILL ONCE AGAIN BE LIMITED TO BELOW
500 J/KG SO NOT EXPECTING A TON OF THUNDERSTORM ACTIVITY. UPPER
LEVEL TEMPS AND SURFACE TEMPS WILL BE A BIT COOLER TODAY SO THINKING
THAT WILL ALSO LIMIT INSTABILITY.  ANY STORMS THAT DO FORM WILL NOT
BE SEVERE...BUT MAY BE DOWNDRAFT DRIVEN PRODUCING GUSTY WINDS
LIKE YESTERDAY. HIGH TEMPS WILL BE IN THE UPPER 70S...EXCEPT ALONG
THE LAKE SHORE WHERE THE LAKE BREEZE WILL KEEP HIGH TEMPS IN THE
MID 70S.

SHOWERS AND STORMS DISSIPATE THIS EVENING WITH LIGHT SOUTHWEST WINDS
EXPECTED OVERNIGHT.  SKIES SHOULD CLEAR OUT NICELY SO EXPECTING MIN
TEMPS TO APPROACH THE DEWPOINTS. SO LOOKING AT LOWS IN THE UPPER 50S
IN THE OUTLYING AREAS...BUT IN THE LOW 60S DOWNTOWN.

JEE

THURSDAY THROUGH SATURDAY...

THE AREA REMAINS ON THE SOUTHWEST SIDE OF THE EASTERN CANADIAN
UPPER LONG WAVE TROUGH THROUGH THE END OF THE WEEK WITH LITTLE
CHANGE IN THE WEATHER PATTERN. AS IS TYPICALLY THE CASE WITH SUCH
AN ESTABLISHED LONG WAVE...MINOR PERTURBATIONS WILL TRAVERSE
DOWN THE BACK SIDE OF THE TROUGH OVER THE WESTERN GREAT
LAKES. EACH OF THESE LOOK TO BRING SUBTLE ENHANCEMENT TO LOW-
LEVEL CONVERGENCE AND KEEP COOL AIR ALOFT FOR ELONGATED CAPE
PROFILES NEAR PEAK HEATING. ALL IN ALL THESE CONTINUE TO PRESENT
MAINLY AFTERNOON AND EARLY EVENING SCATTERED SHOWER/STORM CHANCES.
THERE CONTINUES FAIR MODEL AGREEMENT ON BRINGING AN UPPER/MID
LEVEL SPEED MAX AND AN ASSOCIATED WAVE SOUTHWARD FOR BETTER
COVERAGE OF AFTERNOON SHOWERS/STORMS. BOTH THE SREF AND GEFS
SUPPORT HIGHER POPS OVER A GOOD AMOUNT OF THE AREA AND WHILE THE
MAGNITUDES OF BOTH MAY BE EXTREME /70 PERCENT PLUS/...THE IDEA OF
SCATTERED COVERAGE MORE SO THAN TODAY AND THURSDAY SEEMS LIKELY.
THE ASSOCIATED SURFACE FRONT HANGS UP OVER THE EASTERN FORECAST
AREA. THE LAKE BREEZE WILL CONTINUE TO ALSO BE A FOCUS FOR SHOWERS
AND STORMS...SO DO HAVE A LITTLE HIGHER POPS IN THE NORTHEAST
FORECAST AREA. VERY SLIGHT TEMPERATURE MODERATION IS EXPECTED
THROUGH THIS TIME.

EARLY NEXT WEEK...
HIGH PRESSURE LOOKS TO PREVAIL SATURDAY NIGHT THROUGH THE LATTER
HALF OF THE WEEKEND. THE UPPER LEVEL PATTERN LOOKS TO FLATTEN
SOMEWHAT WITH A QUICK MOVING SYSTEM NORTH OF THE GREAT LAKES
ADVERTISED EARLY NEXT WEEK BY GUIDANCE. THIS LOOKS TO STEER A COOL
FRONT INTO THE REGION WITH LARGE DISCREPANCY ON TIMING AND JUST
HOW FAR SOUTH THIS REACHES. HAVE NOT MADE ANY CHANGES TO A WELL-
VERIFYING BLEND OF GUIDANCE BESIDES INCHING UP TEMPS A COUPLE
DEGREES ON MONDAY AHEAD OF THIS COOL FRONTAL FEATURE.

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* LAKE BREEZE EXPECTED WITH WINDS SHIFTING E-NE ARND 10
  KT...THROUGH MDW AROUND 1930 UTC AND ORD BETWEEN 20 AND 21 UTC.

* WIDELY SCT SHRA THIS AFTN AND EARLY EVENING. A FEW TSRA ALSO
  PSBL.

KJB

//DISCUSSION...UPDATED 18Z...

A LIGHT WIND FIELD ACROSS THE AREA IS ALLOWING A LAKE BREEZE TO
MAKE SOME GOOD PROGRESS INLAND ACROSS NORTHEASTERN ILLINOIS EARLY
THIS AFTERNOON. CURRENT TIMING LOOKS TO PUT THE BOUNDARY THROUGH
KMDW AROUND 1930 UTC AND THROUGH KORD IN THE 20 TO 21 UTC TIME
FRAME. WINDS DO NOT APPEAR TO BE OVERLY STRONG BEHIND THE LAKE
BREEZE...WITH GENERALLY ONLY AROUND 10 KT OF EAST-NORTHEASTERLY
FLOW EXPECTED. THE WINDS WILL GRADUALLY SHIFT BACK OUT OF THE
WEST-SOUTHWEST TONIGHT INTO THURSDAY. ANOTHER LAKE BREEZE MAY
DEVELOP ON THURSDAY. HOWEVER...WITH A SLIGHTLY STRONGER WEST-
SOUTHWESTERLY WIND FIELD EXPECTED ON THURSDAY...THE LAKE BREEZE
MAY STRUGGLE TO REACH THE TERMINALS.

THE OTHER CONCERN THIS AFTERNOON WILL...SIMILAR TO YESTERDAY...BE
THE THREAT FOR SOME WIDELY SCATTERED SHOWERS AND PERHAPS A
THUNDERSTORM ACROSS THE AREA. CUMULUS CLOUDS WILL LIKELY BE ON AN
UPTICK OVER THE NEXT HOUR OR SO AS TEMPERATURES CONTINUE TO WARM
THROUGH THE MID AND UPPER 70S. THIS CLOUD COVER COULD EVEN LEAD TO A
PERIOD OF LOWER END VFR CIG AROUND 4000 FEET AGL...ESPECIALLY AHEAD
OF THE LAKE BREEZE BOUNDARY. GIVEN THE LOWER AREAL COVERAGE
EXPECTED...I WILL CONTINUE WITH THE VCSH AND LEAVE THE MENTION OF
THUNDER OUT OF THE TAF AT THIS TIME.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM-HIGH WITH LAKE BREEZE TIMING.

* MEDIUM-HIGH IN ISOLATED TO SCT -SHRA ACROSS THE REGION...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SCHC TSRA EARLY IN THE EVENING...SCHC SHRA LATE
IN THE EVENING.

FRIDAY...CHC SHRA WITH A CHC OF TSRA IN THE AFTN.

SATURDAY...SCHC SHRA IN THE MORNING...CHC OF TSRA IN THE AFTN.

SUNDAY...VFR.

MONDAY...CHC TSRA OVERNIGHT.

TUESDAY...CHC TSRA.

JEE

&&

.MARINE...
200 PM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE THIS AFTERNOON...THOUGH A
WEAK SURFACE LOW/TROUGH HAS DRIFTED TO THE SOUTHERN TIP OF THE LAKE.
THIS GENERALLY RESULTED IN A SHIFT TO NORTHERLY WINDS DOWN THE LAKE.
MEANWHILE AN UPPER LEVEL LOW CONTINUES TO SPIN NEAR JAMES BAY WITH
WITH SURFACE LOWS/TROUGHS EMANATING FROM THIS FEATURE THAT PROGRESS
SOUTH AND EAST AT TIMES WHILE THE STRONGER PARENT SURFACE LOW
REMAINS CLOSER TO JAMES BAY. MEANWHILE HIGH PRESSURE REMAINS IN
CONTROL OF THE CENTRAL AND NORTHERN PLAINS...RESULTING IN SOUTHERLY
WINDS ACROSS THE NORTHERN HALF OF THE LAKE THIS AFTERNOON.

AFTER ONSHORE FLOW IN THE NEARSHORE WATERS THIS EVENING DUE TO THE
PASSING SURFACE TROUGH...EXPECT WINDS TO BECOME MORE UNIFORM THIS
EVENING WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY
MORNING. A COUPLE MORE WEAK TROUGHS/COLD FRONTS WILL PASS THROUGH
THE LAKE AT TIMES THROUGH WEEKS END...WITH ONE THURSDAY NIGHT AND
WITH A BIT MORE PRONOUNCED FRONT FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT AS THE PRESSURE GRADIENT
REMAINS WEAK FOR THE NEAR FUTURE.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS WITH OCCASIONAL THUNDERSTORMS AT TIMES. WHILE THESE
ARE NOT EXPECTED TO BE WIDESPREAD AT ANY GIVEN TIME...ANY STORMS
THAT FORM COULD CREATE GUSTY OUTFLOW WINDS THAT WOULD CREATE
HAZARDOUS CONDITIONS TO BOATERS...SO CAUTION IS URGED DURING THE
LATE AFTERNOON AND EVENING PERIODS THE NEXT FEW DAYS.

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KILX 301742
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1242 PM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 954 AM CDT Wed Jul 30 2014

High pressure extending from the Northern Plains to the Ohio
River Valley is providing mostly sunny and cool conditions to
central Illinois this morning. Main question will be whether or
not any showers will develop within the cyclonic flow pattern
aloft. 14z/9am water vapor imagery shows deep upper low spinning
over Hudson Bay, with short-wave trough rotating around this
feature across southern Michigan. The influence of this wave will
likely remain NE of Illinois today, with scattered showers/thunder
developing across southern Michigan/Northern Indiana this
afternoon. Upper support will be weaker further W/SW, so am not
expecting much precip at all in Illinois. HRRR suggests isolated
showers may fire after 19z, mainly across northern Illinois.
Meanwhile, the NAM12 is completely dry. Have therefore scaled back
PoPs today, with only an isolated shower mention along/north of
I-74 this afternoon. Have also removed evening showers and gone
with a mostly clear forecast for tonight. Zone update has already
been issued.

Barnes
&&

.AVIATION...
ISSUED 1242 PM CDT Wed Jul 30 2014

VFR conditions will prevail through the entire 18z TAF period. SCT
to occasionally BKN diurnal clouds at 4000-5000ft this afternoon
will rapidly dissipate toward sunset, with clear skies expected
overnight. The cycle will repeat on Thursday, with SCT diurnal
cloud cover once again developing by late morning/early afternoon.
Winds will be light from the NW this afternoon, then will shift to
the W/SW on Thursday.

Barnes
&&

.PREV DISCUSSION...
ISSUED 317 AM CDT Wed Jul 30 2014
Forecast and overall atmospheric pattern slow to change right now
as an upper low remains parked over the southern tip of Hudson
Bay...with the trof dominating the eastern half of the CONUS. 500
mb ridge over the west, and sfc high pressure building into the
Midwest with northwesterly flow aloft. Forecast driven by slowly
warming temperatures, still below normal for late July, light
winds, and afternoon showers. Next chance for a slightly more
substantial chance for thunderstorms arrives on Friday, with a
wave diving into the upper trof and helping to enhance the
dynamics. Overall, very little in the forecast warranting more
than a chance/scattered mention, and not many changes expected
until the pattern breaks later in the weekend.

SHORT TERM...Today and tomorrow...
Partly cloudy afternoon skies with slight chance for some
afternoon showers and iso thunder... with the better chances to
the northeast. High temperatures upper 70s/low 80s...and overnight
lows dropping to upper 50s/near 60 with mostly clear skies. Upper
low anchored over southeastern Canada keeps the weather in a
pretty stagnant pattern and below normal temps in the Midwest.

LONG TERM...Friday through Tuesday...
Best chances for showers and thunderstorms moving in for Friday...
as a wave rotates through the trof and enhances chances for
scattered showers and thunderstorms. Models pretty consistent with
this feature...though coverage is not expected to be widespread
just yet. High pressure dominating into the weekend as the sfc
ridge axis moves into the region. Winds remain light and variable
and dry forecast as the upper trof finally starts to progress
across into the NE. Chances for more significant weather starting
to return Tues/Wed as a more active and progressive flow sets up
across the country.

HJS


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KILX 301742
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1242 PM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 954 AM CDT Wed Jul 30 2014

High pressure extending from the Northern Plains to the Ohio
River Valley is providing mostly sunny and cool conditions to
central Illinois this morning. Main question will be whether or
not any showers will develop within the cyclonic flow pattern
aloft. 14z/9am water vapor imagery shows deep upper low spinning
over Hudson Bay, with short-wave trough rotating around this
feature across southern Michigan. The influence of this wave will
likely remain NE of Illinois today, with scattered showers/thunder
developing across southern Michigan/Northern Indiana this
afternoon. Upper support will be weaker further W/SW, so am not
expecting much precip at all in Illinois. HRRR suggests isolated
showers may fire after 19z, mainly across northern Illinois.
Meanwhile, the NAM12 is completely dry. Have therefore scaled back
PoPs today, with only an isolated shower mention along/north of
I-74 this afternoon. Have also removed evening showers and gone
with a mostly clear forecast for tonight. Zone update has already
been issued.

Barnes
&&

.AVIATION...
ISSUED 1242 PM CDT Wed Jul 30 2014

VFR conditions will prevail through the entire 18z TAF period. SCT
to occasionally BKN diurnal clouds at 4000-5000ft this afternoon
will rapidly dissipate toward sunset, with clear skies expected
overnight. The cycle will repeat on Thursday, with SCT diurnal
cloud cover once again developing by late morning/early afternoon.
Winds will be light from the NW this afternoon, then will shift to
the W/SW on Thursday.

Barnes
&&

.PREV DISCUSSION...
ISSUED 317 AM CDT Wed Jul 30 2014
Forecast and overall atmospheric pattern slow to change right now
as an upper low remains parked over the southern tip of Hudson
Bay...with the trof dominating the eastern half of the CONUS. 500
mb ridge over the west, and sfc high pressure building into the
Midwest with northwesterly flow aloft. Forecast driven by slowly
warming temperatures, still below normal for late July, light
winds, and afternoon showers. Next chance for a slightly more
substantial chance for thunderstorms arrives on Friday, with a
wave diving into the upper trof and helping to enhance the
dynamics. Overall, very little in the forecast warranting more
than a chance/scattered mention, and not many changes expected
until the pattern breaks later in the weekend.

SHORT TERM...Today and tomorrow...
Partly cloudy afternoon skies with slight chance for some
afternoon showers and iso thunder... with the better chances to
the northeast. High temperatures upper 70s/low 80s...and overnight
lows dropping to upper 50s/near 60 with mostly clear skies. Upper
low anchored over southeastern Canada keeps the weather in a
pretty stagnant pattern and below normal temps in the Midwest.

LONG TERM...Friday through Tuesday...
Best chances for showers and thunderstorms moving in for Friday...
as a wave rotates through the trof and enhances chances for
scattered showers and thunderstorms. Models pretty consistent with
this feature...though coverage is not expected to be widespread
just yet. High pressure dominating into the weekend as the sfc
ridge axis moves into the region. Winds remain light and variable
and dry forecast as the upper trof finally starts to progress
across into the NE. Chances for more significant weather starting
to return Tues/Wed as a more active and progressive flow sets up
across the country.

HJS


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KILX 301742
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1242 PM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 954 AM CDT Wed Jul 30 2014

High pressure extending from the Northern Plains to the Ohio
River Valley is providing mostly sunny and cool conditions to
central Illinois this morning. Main question will be whether or
not any showers will develop within the cyclonic flow pattern
aloft. 14z/9am water vapor imagery shows deep upper low spinning
over Hudson Bay, with short-wave trough rotating around this
feature across southern Michigan. The influence of this wave will
likely remain NE of Illinois today, with scattered showers/thunder
developing across southern Michigan/Northern Indiana this
afternoon. Upper support will be weaker further W/SW, so am not
expecting much precip at all in Illinois. HRRR suggests isolated
showers may fire after 19z, mainly across northern Illinois.
Meanwhile, the NAM12 is completely dry. Have therefore scaled back
PoPs today, with only an isolated shower mention along/north of
I-74 this afternoon. Have also removed evening showers and gone
with a mostly clear forecast for tonight. Zone update has already
been issued.

Barnes
&&

.AVIATION...
ISSUED 1242 PM CDT Wed Jul 30 2014

VFR conditions will prevail through the entire 18z TAF period. SCT
to occasionally BKN diurnal clouds at 4000-5000ft this afternoon
will rapidly dissipate toward sunset, with clear skies expected
overnight. The cycle will repeat on Thursday, with SCT diurnal
cloud cover once again developing by late morning/early afternoon.
Winds will be light from the NW this afternoon, then will shift to
the W/SW on Thursday.

Barnes
&&

.PREV DISCUSSION...
ISSUED 317 AM CDT Wed Jul 30 2014
Forecast and overall atmospheric pattern slow to change right now
as an upper low remains parked over the southern tip of Hudson
Bay...with the trof dominating the eastern half of the CONUS. 500
mb ridge over the west, and sfc high pressure building into the
Midwest with northwesterly flow aloft. Forecast driven by slowly
warming temperatures, still below normal for late July, light
winds, and afternoon showers. Next chance for a slightly more
substantial chance for thunderstorms arrives on Friday, with a
wave diving into the upper trof and helping to enhance the
dynamics. Overall, very little in the forecast warranting more
than a chance/scattered mention, and not many changes expected
until the pattern breaks later in the weekend.

SHORT TERM...Today and tomorrow...
Partly cloudy afternoon skies with slight chance for some
afternoon showers and iso thunder... with the better chances to
the northeast. High temperatures upper 70s/low 80s...and overnight
lows dropping to upper 50s/near 60 with mostly clear skies. Upper
low anchored over southeastern Canada keeps the weather in a
pretty stagnant pattern and below normal temps in the Midwest.

LONG TERM...Friday through Tuesday...
Best chances for showers and thunderstorms moving in for Friday...
as a wave rotates through the trof and enhances chances for
scattered showers and thunderstorms. Models pretty consistent with
this feature...though coverage is not expected to be widespread
just yet. High pressure dominating into the weekend as the sfc
ridge axis moves into the region. Winds remain light and variable
and dry forecast as the upper trof finally starts to progress
across into the NE. Chances for more significant weather starting
to return Tues/Wed as a more active and progressive flow sets up
across the country.

HJS


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KILX 301742
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1242 PM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 954 AM CDT Wed Jul 30 2014

High pressure extending from the Northern Plains to the Ohio
River Valley is providing mostly sunny and cool conditions to
central Illinois this morning. Main question will be whether or
not any showers will develop within the cyclonic flow pattern
aloft. 14z/9am water vapor imagery shows deep upper low spinning
over Hudson Bay, with short-wave trough rotating around this
feature across southern Michigan. The influence of this wave will
likely remain NE of Illinois today, with scattered showers/thunder
developing across southern Michigan/Northern Indiana this
afternoon. Upper support will be weaker further W/SW, so am not
expecting much precip at all in Illinois. HRRR suggests isolated
showers may fire after 19z, mainly across northern Illinois.
Meanwhile, the NAM12 is completely dry. Have therefore scaled back
PoPs today, with only an isolated shower mention along/north of
I-74 this afternoon. Have also removed evening showers and gone
with a mostly clear forecast for tonight. Zone update has already
been issued.

Barnes
&&

.AVIATION...
ISSUED 1242 PM CDT Wed Jul 30 2014

VFR conditions will prevail through the entire 18z TAF period. SCT
to occasionally BKN diurnal clouds at 4000-5000ft this afternoon
will rapidly dissipate toward sunset, with clear skies expected
overnight. The cycle will repeat on Thursday, with SCT diurnal
cloud cover once again developing by late morning/early afternoon.
Winds will be light from the NW this afternoon, then will shift to
the W/SW on Thursday.

Barnes
&&

.PREV DISCUSSION...
ISSUED 317 AM CDT Wed Jul 30 2014
Forecast and overall atmospheric pattern slow to change right now
as an upper low remains parked over the southern tip of Hudson
Bay...with the trof dominating the eastern half of the CONUS. 500
mb ridge over the west, and sfc high pressure building into the
Midwest with northwesterly flow aloft. Forecast driven by slowly
warming temperatures, still below normal for late July, light
winds, and afternoon showers. Next chance for a slightly more
substantial chance for thunderstorms arrives on Friday, with a
wave diving into the upper trof and helping to enhance the
dynamics. Overall, very little in the forecast warranting more
than a chance/scattered mention, and not many changes expected
until the pattern breaks later in the weekend.

SHORT TERM...Today and tomorrow...
Partly cloudy afternoon skies with slight chance for some
afternoon showers and iso thunder... with the better chances to
the northeast. High temperatures upper 70s/low 80s...and overnight
lows dropping to upper 50s/near 60 with mostly clear skies. Upper
low anchored over southeastern Canada keeps the weather in a
pretty stagnant pattern and below normal temps in the Midwest.

LONG TERM...Friday through Tuesday...
Best chances for showers and thunderstorms moving in for Friday...
as a wave rotates through the trof and enhances chances for
scattered showers and thunderstorms. Models pretty consistent with
this feature...though coverage is not expected to be widespread
just yet. High pressure dominating into the weekend as the sfc
ridge axis moves into the region. Winds remain light and variable
and dry forecast as the upper trof finally starts to progress
across into the NE. Chances for more significant weather starting
to return Tues/Wed as a more active and progressive flow sets up
across the country.

HJS


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 301709
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1209 PM CDT WED JUL 30 2014

.DISCUSSION...
315 AM CDT

SYNOPSIS...TODAY WILL BE VERY SIMILAR TO YESTERDAY WITH A LAKE
BREEZE PUSHING INLAND.  SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL FORM ALONG THE BOUNDARY. THERE ARE CHANCES FOR AFTERNOON
THUNDERSTORMS THROUGH SATURDAY WITH THE BETTER CHANCES FRIDAY AND
SATURDAY.  ADDITIONAL THUNDERSTORMS ARE POSSIBLE EARLY NEXT WEEK.
TEMPERATURES SLOWLY RISE THROUGH EARLY NEXT WEEK WITH MID 80 HIGH
TEMPS POSSIBLE MONDAY.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS STILL PARKED OVER JAMES BAY. A SHORT WAVE
TROUGH/COLD FRONT ASSOCIATED WITH THE LOW IS OVER CENTRAL WI AND IT
WILL SLIDE DOWN THE LAKE THROUGH THIS MORNING. THE FRONT LOSES STEAM
THIS AFTERNOON AND STALLS OVER NORTHERN IL AND IN.

A LAKE BREEZE IS ALSO EXPECTED TODAY SO THERE SHOULD BE ADEQUATE
FORCING FOR SHOWERS AND A FEW STORMS BETWEEN THE LAKE BREEZE AND
STALLED OUT COLD FRONT.  CAPE WILL ONCE AGAIN BE LIMITED TO BELOW
500 J/KG SO NOT EXPECTING A TON OF THUNDERSTORM ACTIVITY. UPPER
LEVEL TEMPS AND SURFACE TEMPS WILL BE A BIT COOLER TODAY SO THINKING
THAT WILL ALSO LIMIT INSTABILITY.  ANY STORMS THAT DO FORM WILL NOT
BE SEVERE...BUT MAY BE DOWNDRAFT DRIVEN PRODUCING GUSTY WINDS
LIKE YESTERDAY. HIGH TEMPS WILL BE IN THE UPPER 70S...EXCEPT ALONG
THE LAKE SHORE WHERE THE LAKE BREEZE WILL KEEP HIGH TEMPS IN THE
MID 70S.

SHOWERS AND STORMS DISSIPATE THIS EVENING WITH LIGHT SOUTHWEST WINDS
EXPECTED OVERNIGHT.  SKIES SHOULD CLEAR OUT NICELY SO EXPECTING MIN
TEMPS TO APPROACH THE DEWPOINTS. SO LOOKING AT LOWS IN THE UPPER 50S
IN THE OUTLYING AREAS...BUT IN THE LOW 60S DOWNTOWN.

JEE

THURSDAY THROUGH SATURDAY...

THE AREA REMAINS ON THE SOUTHWEST SIDE OF THE EASTERN CANADIAN
UPPER LONG WAVE TROUGH THROUGH THE END OF THE WEEK WITH LITTLE
CHANGE IN THE WEATHER PATTERN. AS IS TYPICALLY THE CASE WITH SUCH
AN ESTABLISHED LONG WAVE...MINOR PERTURBATIONS WILL TRAVERSE
DOWN THE BACK SIDE OF THE TROUGH OVER THE WESTERN GREAT
LAKES. EACH OF THESE LOOK TO BRING SUBTLE ENHANCEMENT TO LOW-
LEVEL CONVERGENCE AND KEEP COOL AIR ALOFT FOR ELONGATED CAPE
PROFILES NEAR PEAK HEATING. ALL IN ALL THESE CONTINUE TO PRESENT
MAINLY AFTERNOON AND EARLY EVENING SCATTERED SHOWER/STORM CHANCES.
THERE CONTINUES FAIR MODEL AGREEMENT ON BRINGING AN UPPER/MID
LEVEL SPEED MAX AND AN ASSOCIATED WAVE SOUTHWARD FOR BETTER
COVERAGE OF AFTERNOON SHOWERS/STORMS. BOTH THE SREF AND GEFS
SUPPORT HIGHER POPS OVER A GOOD AMOUNT OF THE AREA AND WHILE THE
MAGNITUDES OF BOTH MAY BE EXTREME /70 PERCENT PLUS/...THE IDEA OF
SCATTERED COVERAGE MORE SO THAN TODAY AND THURSDAY SEEMS LIKELY.
THE ASSOCIATED SURFACE FRONT HANGS UP OVER THE EASTERN FORECAST
AREA. THE LAKE BREEZE WILL CONTINUE TO ALSO BE A FOCUS FOR SHOWERS
AND STORMS...SO DO HAVE A LITTLE HIGHER POPS IN THE NORTHEAST
FORECAST AREA. VERY SLIGHT TEMPERATURE MODERATION IS EXPECTED
THROUGH THIS TIME.

EARLY NEXT WEEK...
HIGH PRESSURE LOOKS TO PREVAIL SATURDAY NIGHT THROUGH THE LATTER
HALF OF THE WEEKEND. THE UPPER LEVEL PATTERN LOOKS TO FLATTEN
SOMEWHAT WITH A QUICK MOVING SYSTEM NORTH OF THE GREAT LAKES
ADVERTISED EARLY NEXT WEEK BY GUIDANCE. THIS LOOKS TO STEER A COOL
FRONT INTO THE REGION WITH LARGE DISCREPANCY ON TIMING AND JUST
HOW FAR SOUTH THIS REACHES. HAVE NOT MADE ANY CHANGES TO A WELL-
VERIFYING BLEND OF GUIDANCE BESIDES INCHING UP TEMPS A COUPLE
DEGREES ON MONDAY AHEAD OF THIS COOL FRONTAL FEATURE.

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* LAKE BREEZE EXPECTED WITH WINDS SHIFTING E-NE ARND 10
  KT...THROUGH MDW AROUND 1930 UTC AND ORD BETWEEN 20 AND 21 UTC.

* WIDELY SCT SHRA THIS AFTN AND EARLY EVENING. A FEW TSRA ALSO
  PSBL.

KJB

//DISCUSSION...UPDATED 18Z...

A LIGHT WIND FIELD ACROSS THE AREA IS ALLOWING A LAKE BREEZE TO
MAKE SOME GOOD PROGRESS INLAND ACROSS NORTHEASTERN ILLINOIS EARLY
THIS AFTERNOON. CURRENT TIMING LOOKS TO PUT THE BOUNDARY THROUGH
KMDW AROUND 1930 UTC AND THROUGH KORD IN THE 20 TO 21 UTC TIME
FRAME. WINDS DO NOT APPEAR TO BE OVERLY STRONG BEHIND THE LAKE
BREEZE...WITH GENERALLY ONLY AROUND 10 KT OF EAST-NORTHEASTERLY
FLOW EXPECTED. THE WINDS WILL GRADUALLY SHIFT BACK OUT OF THE
WEST-SOUTHWEST TONIGHT INTO THURSDAY. ANOTHER LAKE BREEZE MAY
DEVELOP ON THURSDAY. HOWEVER...WITH A SLIGHTLY STRONGER WEST-
SOUTHWESTERLY WIND FIELD EXPECTED ON THURSDAY...THE LAKE BREEZE
MAY STRUGGLE TO REACH THE TERMINALS.

THE OTHER CONCERN THIS AFTERNOON WILL...SIMILAR TO YESTERDAY...BE
THE THREAT FOR SOME WIDELY SCATTERED SHOWERS AND PERHAPS A
THUNDERSTORM ACROSS THE AREA. CUMULUS CLOUDS WILL LIKELY BE ON AN
UPTICK OVER THE NEXT HOUR OR SO AS TEMPERATURES CONTINUE TO WARM
THROUGH THE MID AND UPPER 70S. THIS CLOUD COVER COULD EVEN LEAD TO A
PERIOD OF LOWER END VFR CIG AROUND 4000 FEET AGL...ESPECIALLY AHEAD
OF THE LAKE BREEZE BOUNDARY. GIVEN THE LOWER AREAL COVERAGE
EXPECTED...I WILL CONTINUE WITH THE VCSH AND LEAVE THE MENTION OF
THUNDER OUT OF THE TAF AT THIS TIME.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM-HIGH WITH LAKE BREEZE TIMING.

* MEDIUM-HIGH IN ISOLATED TO SCT -SHRA ACROSS THE REGION...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SCHC TSRA EARLY IN THE EVENING...SCHC SHRA LATE
IN THE EVENING.

FRIDAY...CHC SHRA WITH A CHC OF TSRA IN THE AFTN.

SATURDAY...SCHC SHRA IN THE MORNING...CHC OF TSRA IN THE AFTN.

SUNDAY...VFR.

MONDAY...CHC TSRA OVERNIGHT.

TUESDAY...CHC TSRA.

JEE

&&

.MARINE...
255 AM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE WITH A WEAK COLD
FRONT/UPPER LEVEL WAVE MOVING DOWN THE LAKE EARLY THIS MORNING.
WINDS BECOME NORTH AROUND 10 KT BEHIND THE FRONT. HIGH PRESSURE
OVER THE PLAINS ATTEMPTS TO SPREAD EAST TODAY LEADING TO A
CONTINUED VERY WEAK PRESSURE GRADIENT. ONSHORE FLOW IS EXPECTED
ACROSS NEARSHORE AREAS LEADING TO VARIABLE WINDS 10 KT OR LESS AT
TIMES OVER THE OPEN WATERS. WINDS BECOME MORE UNIFORM THIS EVENING
WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY MORNING. A
COUPLE MORE WEAK COOL FRONTS ARE EXPECTED BY WEEKS END...AT THIS
TIME THURSDAY NIGHT AND AGAIN FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS AND SOME STORMS MAINLY DRIVEN BY THE HEATING OF
THE DAY OVER LAND. SOME OF THESE COULD BE ABLE TO MOVE INTO
NEARSHORE AREAS ON THE WESTERN SIDE OF THE LAKE AS SEEN OVER WI/IL
SHORES LAST EVENING...AND PROFILES OVER LAND DO SUPPORT SOME QUICK
RACING OUTFLOWS/GUST FRONTS FROM SHOWERS THE NEXT FEW DAYS...SO
SOMETHING FOR NEARSHORE MARINERS TO KEEP SOME TABS ON DESPITE THE
MAINLY QUIET WIND/WAVE REGIME.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 301709
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1209 PM CDT WED JUL 30 2014

.DISCUSSION...
315 AM CDT

SYNOPSIS...TODAY WILL BE VERY SIMILAR TO YESTERDAY WITH A LAKE
BREEZE PUSHING INLAND.  SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL FORM ALONG THE BOUNDARY. THERE ARE CHANCES FOR AFTERNOON
THUNDERSTORMS THROUGH SATURDAY WITH THE BETTER CHANCES FRIDAY AND
SATURDAY.  ADDITIONAL THUNDERSTORMS ARE POSSIBLE EARLY NEXT WEEK.
TEMPERATURES SLOWLY RISE THROUGH EARLY NEXT WEEK WITH MID 80 HIGH
TEMPS POSSIBLE MONDAY.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS STILL PARKED OVER JAMES BAY. A SHORT WAVE
TROUGH/COLD FRONT ASSOCIATED WITH THE LOW IS OVER CENTRAL WI AND IT
WILL SLIDE DOWN THE LAKE THROUGH THIS MORNING. THE FRONT LOSES STEAM
THIS AFTERNOON AND STALLS OVER NORTHERN IL AND IN.

A LAKE BREEZE IS ALSO EXPECTED TODAY SO THERE SHOULD BE ADEQUATE
FORCING FOR SHOWERS AND A FEW STORMS BETWEEN THE LAKE BREEZE AND
STALLED OUT COLD FRONT.  CAPE WILL ONCE AGAIN BE LIMITED TO BELOW
500 J/KG SO NOT EXPECTING A TON OF THUNDERSTORM ACTIVITY. UPPER
LEVEL TEMPS AND SURFACE TEMPS WILL BE A BIT COOLER TODAY SO THINKING
THAT WILL ALSO LIMIT INSTABILITY.  ANY STORMS THAT DO FORM WILL NOT
BE SEVERE...BUT MAY BE DOWNDRAFT DRIVEN PRODUCING GUSTY WINDS
LIKE YESTERDAY. HIGH TEMPS WILL BE IN THE UPPER 70S...EXCEPT ALONG
THE LAKE SHORE WHERE THE LAKE BREEZE WILL KEEP HIGH TEMPS IN THE
MID 70S.

SHOWERS AND STORMS DISSIPATE THIS EVENING WITH LIGHT SOUTHWEST WINDS
EXPECTED OVERNIGHT.  SKIES SHOULD CLEAR OUT NICELY SO EXPECTING MIN
TEMPS TO APPROACH THE DEWPOINTS. SO LOOKING AT LOWS IN THE UPPER 50S
IN THE OUTLYING AREAS...BUT IN THE LOW 60S DOWNTOWN.

JEE

THURSDAY THROUGH SATURDAY...

THE AREA REMAINS ON THE SOUTHWEST SIDE OF THE EASTERN CANADIAN
UPPER LONG WAVE TROUGH THROUGH THE END OF THE WEEK WITH LITTLE
CHANGE IN THE WEATHER PATTERN. AS IS TYPICALLY THE CASE WITH SUCH
AN ESTABLISHED LONG WAVE...MINOR PERTURBATIONS WILL TRAVERSE
DOWN THE BACK SIDE OF THE TROUGH OVER THE WESTERN GREAT
LAKES. EACH OF THESE LOOK TO BRING SUBTLE ENHANCEMENT TO LOW-
LEVEL CONVERGENCE AND KEEP COOL AIR ALOFT FOR ELONGATED CAPE
PROFILES NEAR PEAK HEATING. ALL IN ALL THESE CONTINUE TO PRESENT
MAINLY AFTERNOON AND EARLY EVENING SCATTERED SHOWER/STORM CHANCES.
THERE CONTINUES FAIR MODEL AGREEMENT ON BRINGING AN UPPER/MID
LEVEL SPEED MAX AND AN ASSOCIATED WAVE SOUTHWARD FOR BETTER
COVERAGE OF AFTERNOON SHOWERS/STORMS. BOTH THE SREF AND GEFS
SUPPORT HIGHER POPS OVER A GOOD AMOUNT OF THE AREA AND WHILE THE
MAGNITUDES OF BOTH MAY BE EXTREME /70 PERCENT PLUS/...THE IDEA OF
SCATTERED COVERAGE MORE SO THAN TODAY AND THURSDAY SEEMS LIKELY.
THE ASSOCIATED SURFACE FRONT HANGS UP OVER THE EASTERN FORECAST
AREA. THE LAKE BREEZE WILL CONTINUE TO ALSO BE A FOCUS FOR SHOWERS
AND STORMS...SO DO HAVE A LITTLE HIGHER POPS IN THE NORTHEAST
FORECAST AREA. VERY SLIGHT TEMPERATURE MODERATION IS EXPECTED
THROUGH THIS TIME.

EARLY NEXT WEEK...
HIGH PRESSURE LOOKS TO PREVAIL SATURDAY NIGHT THROUGH THE LATTER
HALF OF THE WEEKEND. THE UPPER LEVEL PATTERN LOOKS TO FLATTEN
SOMEWHAT WITH A QUICK MOVING SYSTEM NORTH OF THE GREAT LAKES
ADVERTISED EARLY NEXT WEEK BY GUIDANCE. THIS LOOKS TO STEER A COOL
FRONT INTO THE REGION WITH LARGE DISCREPANCY ON TIMING AND JUST
HOW FAR SOUTH THIS REACHES. HAVE NOT MADE ANY CHANGES TO A WELL-
VERIFYING BLEND OF GUIDANCE BESIDES INCHING UP TEMPS A COUPLE
DEGREES ON MONDAY AHEAD OF THIS COOL FRONTAL FEATURE.

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* LAKE BREEZE EXPECTED WITH WINDS SHIFTING E-NE ARND 10
  KT...THROUGH MDW AROUND 1930 UTC AND ORD BETWEEN 20 AND 21 UTC.

* WIDELY SCT SHRA THIS AFTN AND EARLY EVENING. A FEW TSRA ALSO
  PSBL.

KJB

//DISCUSSION...UPDATED 18Z...

A LIGHT WIND FIELD ACROSS THE AREA IS ALLOWING A LAKE BREEZE TO
MAKE SOME GOOD PROGRESS INLAND ACROSS NORTHEASTERN ILLINOIS EARLY
THIS AFTERNOON. CURRENT TIMING LOOKS TO PUT THE BOUNDARY THROUGH
KMDW AROUND 1930 UTC AND THROUGH KORD IN THE 20 TO 21 UTC TIME
FRAME. WINDS DO NOT APPEAR TO BE OVERLY STRONG BEHIND THE LAKE
BREEZE...WITH GENERALLY ONLY AROUND 10 KT OF EAST-NORTHEASTERLY
FLOW EXPECTED. THE WINDS WILL GRADUALLY SHIFT BACK OUT OF THE
WEST-SOUTHWEST TONIGHT INTO THURSDAY. ANOTHER LAKE BREEZE MAY
DEVELOP ON THURSDAY. HOWEVER...WITH A SLIGHTLY STRONGER WEST-
SOUTHWESTERLY WIND FIELD EXPECTED ON THURSDAY...THE LAKE BREEZE
MAY STRUGGLE TO REACH THE TERMINALS.

THE OTHER CONCERN THIS AFTERNOON WILL...SIMILAR TO YESTERDAY...BE
THE THREAT FOR SOME WIDELY SCATTERED SHOWERS AND PERHAPS A
THUNDERSTORM ACROSS THE AREA. CUMULUS CLOUDS WILL LIKELY BE ON AN
UPTICK OVER THE NEXT HOUR OR SO AS TEMPERATURES CONTINUE TO WARM
THROUGH THE MID AND UPPER 70S. THIS CLOUD COVER COULD EVEN LEAD TO A
PERIOD OF LOWER END VFR CIG AROUND 4000 FEET AGL...ESPECIALLY AHEAD
OF THE LAKE BREEZE BOUNDARY. GIVEN THE LOWER AREAL COVERAGE
EXPECTED...I WILL CONTINUE WITH THE VCSH AND LEAVE THE MENTION OF
THUNDER OUT OF THE TAF AT THIS TIME.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM-HIGH WITH LAKE BREEZE TIMING.

* MEDIUM-HIGH IN ISOLATED TO SCT -SHRA ACROSS THE REGION...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SCHC TSRA EARLY IN THE EVENING...SCHC SHRA LATE
IN THE EVENING.

FRIDAY...CHC SHRA WITH A CHC OF TSRA IN THE AFTN.

SATURDAY...SCHC SHRA IN THE MORNING...CHC OF TSRA IN THE AFTN.

SUNDAY...VFR.

MONDAY...CHC TSRA OVERNIGHT.

TUESDAY...CHC TSRA.

JEE

&&

.MARINE...
255 AM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE WITH A WEAK COLD
FRONT/UPPER LEVEL WAVE MOVING DOWN THE LAKE EARLY THIS MORNING.
WINDS BECOME NORTH AROUND 10 KT BEHIND THE FRONT. HIGH PRESSURE
OVER THE PLAINS ATTEMPTS TO SPREAD EAST TODAY LEADING TO A
CONTINUED VERY WEAK PRESSURE GRADIENT. ONSHORE FLOW IS EXPECTED
ACROSS NEARSHORE AREAS LEADING TO VARIABLE WINDS 10 KT OR LESS AT
TIMES OVER THE OPEN WATERS. WINDS BECOME MORE UNIFORM THIS EVENING
WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY MORNING. A
COUPLE MORE WEAK COOL FRONTS ARE EXPECTED BY WEEKS END...AT THIS
TIME THURSDAY NIGHT AND AGAIN FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS AND SOME STORMS MAINLY DRIVEN BY THE HEATING OF
THE DAY OVER LAND. SOME OF THESE COULD BE ABLE TO MOVE INTO
NEARSHORE AREAS ON THE WESTERN SIDE OF THE LAKE AS SEEN OVER WI/IL
SHORES LAST EVENING...AND PROFILES OVER LAND DO SUPPORT SOME QUICK
RACING OUTFLOWS/GUST FRONTS FROM SHOWERS THE NEXT FEW DAYS...SO
SOMETHING FOR NEARSHORE MARINERS TO KEEP SOME TABS ON DESPITE THE
MAINLY QUIET WIND/WAVE REGIME.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 301601
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1101 AM CDT WED JUL 30 2014

.DISCUSSION...
315 AM CDT

SYNOPSIS...TODAY WILL BE VERY SIMILAR TO YESTERDAY WITH A LAKE
BREEZE PUSHING INLAND.  SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL FORM ALONG THE BOUNDARY. THERE ARE CHANCES FOR AFTERNOON
THUNDERSTORMS THROUGH SATURDAY WITH THE BETTER CHANCES FRIDAY AND
SATURDAY.  ADDITIONAL THUNDERSTORMS ARE POSSIBLE EARLY NEXT WEEK.
TEMPERATURES SLOWLY RISE THROUGH EARLY NEXT WEEK WITH MID 80 HIGH
TEMPS POSSIBLE MONDAY.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS STILL PARKED OVER JAMES BAY. A SHORT WAVE
TROUGH/COLD FRONT ASSOCIATED WITH THE LOW IS OVER CENTRAL WI AND IT
WILL SLIDE DOWN THE LAKE THROUGH THIS MORNING. THE FRONT LOSES STEAM
THIS AFTERNOON AND STALLS OVER NORTHERN IL AND IN.

A LAKE BREEZE IS ALSO EXPECTED TODAY SO THERE SHOULD BE ADEQUATE
FORCING FOR SHOWERS AND A FEW STORMS BETWEEN THE LAKE BREEZE AND
STALLED OUT COLD FRONT.  CAPE WILL ONCE AGAIN BE LIMITED TO BELOW
500 J/KG SO NOT EXPECTING A TON OF THUNDERSTORM ACTIVITY. UPPER
LEVEL TEMPS AND SURFACE TEMPS WILL BE A BIT COOLER TODAY SO THINKING
THAT WILL ALSO LIMIT INSTABILITY.  ANY STORMS THAT DO FORM WILL NOT
BE SEVERE...BUT MAY BE DOWNDRAFT DRIVEN PRODUCING GUSTY WINDS
LIKE YESTERDAY. HIGH TEMPS WILL BE IN THE UPPER 70S...EXCEPT ALONG
THE LAKE SHORE WHERE THE LAKE BREEZE WILL KEEP HIGH TEMPS IN THE
MID 70S.

SHOWERS AND STORMS DISSIPATE THIS EVENING WITH LIGHT SOUTHWEST WINDS
EXPECTED OVERNIGHT.  SKIES SHOULD CLEAR OUT NICELY SO EXPECTING MIN
TEMPS TO APPROACH THE DEWPOINTS. SO LOOKING AT LOWS IN THE UPPER 50S
IN THE OUTLYING AREAS...BUT IN THE LOW 60S DOWNTOWN.

JEE

THURSDAY THROUGH SATURDAY...

THE AREA REMAINS ON THE SOUTHWEST SIDE OF THE EASTERN CANADIAN
UPPER LONG WAVE TROUGH THROUGH THE END OF THE WEEK WITH LITTLE
CHANGE IN THE WEATHER PATTERN. AS IS TYPICALLY THE CASE WITH SUCH
AN ESTABLISHED LONG WAVE...MINOR PERTURBATIONS WILL TRAVERSE
DOWN THE BACK SIDE OF THE TROUGH OVER THE WESTERN GREAT
LAKES. EACH OF THESE LOOK TO BRING SUBTLE ENHANCEMENT TO LOW-
LEVEL CONVERGENCE AND KEEP COOL AIR ALOFT FOR ELONGATED CAPE
PROFILES NEAR PEAK HEATING. ALL IN ALL THESE CONTINUE TO PRESENT
MAINLY AFTERNOON AND EARLY EVENING SCATTERED SHOWER/STORM CHANCES.
THERE CONTINUES FAIR MODEL AGREEMENT ON BRINGING AN UPPER/MID
LEVEL SPEED MAX AND AN ASSOCIATED WAVE SOUTHWARD FOR BETTER
COVERAGE OF AFTERNOON SHOWERS/STORMS. BOTH THE SREF AND GEFS
SUPPORT HIGHER POPS OVER A GOOD AMOUNT OF THE AREA AND WHILE THE
MAGNITUDES OF BOTH MAY BE EXTREME /70 PERCENT PLUS/...THE IDEA OF
SCATTERED COVERAGE MORE SO THAN TODAY AND THURSDAY SEEMS LIKELY.
THE ASSOCIATED SURFACE FRONT HANGS UP OVER THE EASTERN FORECAST
AREA. THE LAKE BREEZE WILL CONTINUE TO ALSO BE A FOCUS FOR SHOWERS
AND STORMS...SO DO HAVE A LITTLE HIGHER POPS IN THE NORTHEAST
FORECAST AREA. VERY SLIGHT TEMPERATURE MODERATION IS EXPECTED
THROUGH THIS TIME.

EARLY NEXT WEEK...
HIGH PRESSURE LOOKS TO PREVAIL SATURDAY NIGHT THROUGH THE LATTER
HALF OF THE WEEKEND. THE UPPER LEVEL PATTERN LOOKS TO FLATTEN
SOMEWHAT WITH A QUICK MOVING SYSTEM NORTH OF THE GREAT LAKES
ADVERTISED EARLY NEXT WEEK BY GUIDANCE. THIS LOOKS TO STEER A COOL
FRONT INTO THE REGION WITH LARGE DISCREPANCY ON TIMING AND JUST
HOW FAR SOUTH THIS REACHES. HAVE NOT MADE ANY CHANGES TO A WELL-
VERIFYING BLEND OF GUIDANCE BESIDES INCHING UP TEMPS A COUPLE
DEGREES ON MONDAY AHEAD OF THIS COOL FRONTAL FEATURE.

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* LAKE BREEZE EXPECTED WITH WINDS SHIFTING E-NE ARND 10 KT.

* SCT SHRA THIS AFTN AND EVENING. A FEW TSRA ALSO PSBL.

JEE/KB

//DISCUSSION...UPDATED 12Z...

A WEAK COLD FRONT IS PUSHING SOUTH DOWN THE LAKE THIS MORNING AND
IT WILL STALL OUT JUST SOUTH OF THE TERMINALS. WINDS WILL BECOME
NORTHWEST AT 9 KT BEHIND THE FRONT. A LAKE BREEZE IS EXPECTED
TODAY AND IT WILL IMPACT ORD...MDW...AND GYY. NOT SURE IF THE
BREEZE WILL MAKE IT TO DPA SO KEPT A NW WIND AT DPA. WINDS WILL
SHIFT TO NE ARND 10 KT BEHIND THE LAKE BREEZE.

LIKE YESTERDAY...THE LAKE BREEZE WILL BE THE FOCUS FOR SCATTERED
SHOWERS AND A FEW ISOLATED THUNDERSTORMS. NOT EXPECTING AS MANY
THUNDERSTORMS AS YESTERDAY...BUT ANY THUNDERSTORMS THAT DO FORM
WILL HAVE STRONG DOWNDRAFTS AND PRODUCE GUSTY WINDS UP TO 35 KT.

WINDS BACK TO WEST IN THE EVENING AND REMAIN WEST THROUGH THE REST
OF THE PERIOD.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* HIGH CONFIDENCE IN LAKE BREEZE...MEDIUM-HIGH CONFIDENCE IN
  TIMING.

* MEDIUM-HIGH CONFIDENCE IN SHRA DEVELOPMENT AND COVERAGE...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE/KB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SCHC TSRA EARLY IN THE EVENING...SCHC SHRA LATE
IN THE EVENING.

FRIDAY...CHC SHRA WITH A CHC OF TSRA IN THE AFTN.

SATURDAY...SCHC SHRA IN THE MORNING...CHC OF TSRA IN THE AFTN.

SUNDAY...VFR.

MONDAY...CHC TSRA OVERNIGHT.

TUESDAY...CHC TSRA.

JEE

&&

.MARINE...
255 AM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE WITH A WEAK COLD
FRONT/UPPER LEVEL WAVE MOVING DOWN THE LAKE EARLY THIS MORNING.
WINDS BECOME NORTH AROUND 10 KT BEHIND THE FRONT. HIGH PRESSURE
OVER THE PLAINS ATTEMPTS TO SPREAD EAST TODAY LEADING TO A
CONTINUED VERY WEAK PRESSURE GRADIENT. ONSHORE FLOW IS EXPECTED
ACROSS NEARSHORE AREAS LEADING TO VARIABLE WINDS 10 KT OR LESS AT
TIMES OVER THE OPEN WATERS. WINDS BECOME MORE UNIFORM THIS EVENING
WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY MORNING. A
COUPLE MORE WEAK COOL FRONTS ARE EXPECTED BY WEEKS END...AT THIS
TIME THURSDAY NIGHT AND AGAIN FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS AND SOME STORMS MAINLY DRIVEN BY THE HEATING OF
THE DAY OVER LAND. SOME OF THESE COULD BE ABLE TO MOVE INTO
NEARSHORE AREAS ON THE WESTERN SIDE OF THE LAKE AS SEEN OVER WI/IL
SHORES LAST EVENING...AND PROFILES OVER LAND DO SUPPORT SOME QUICK
RACING OUTFLOWS/GUST FRONTS FROM SHOWERS THE NEXT FEW DAYS...SO
SOMETHING FOR NEARSHORE MARINERS TO KEEP SOME TABS ON DESPITE THE
MAINLY QUIET WIND/WAVE REGIME.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 301601
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1101 AM CDT WED JUL 30 2014

.DISCUSSION...
315 AM CDT

SYNOPSIS...TODAY WILL BE VERY SIMILAR TO YESTERDAY WITH A LAKE
BREEZE PUSHING INLAND.  SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL FORM ALONG THE BOUNDARY. THERE ARE CHANCES FOR AFTERNOON
THUNDERSTORMS THROUGH SATURDAY WITH THE BETTER CHANCES FRIDAY AND
SATURDAY.  ADDITIONAL THUNDERSTORMS ARE POSSIBLE EARLY NEXT WEEK.
TEMPERATURES SLOWLY RISE THROUGH EARLY NEXT WEEK WITH MID 80 HIGH
TEMPS POSSIBLE MONDAY.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS STILL PARKED OVER JAMES BAY. A SHORT WAVE
TROUGH/COLD FRONT ASSOCIATED WITH THE LOW IS OVER CENTRAL WI AND IT
WILL SLIDE DOWN THE LAKE THROUGH THIS MORNING. THE FRONT LOSES STEAM
THIS AFTERNOON AND STALLS OVER NORTHERN IL AND IN.

A LAKE BREEZE IS ALSO EXPECTED TODAY SO THERE SHOULD BE ADEQUATE
FORCING FOR SHOWERS AND A FEW STORMS BETWEEN THE LAKE BREEZE AND
STALLED OUT COLD FRONT.  CAPE WILL ONCE AGAIN BE LIMITED TO BELOW
500 J/KG SO NOT EXPECTING A TON OF THUNDERSTORM ACTIVITY. UPPER
LEVEL TEMPS AND SURFACE TEMPS WILL BE A BIT COOLER TODAY SO THINKING
THAT WILL ALSO LIMIT INSTABILITY.  ANY STORMS THAT DO FORM WILL NOT
BE SEVERE...BUT MAY BE DOWNDRAFT DRIVEN PRODUCING GUSTY WINDS
LIKE YESTERDAY. HIGH TEMPS WILL BE IN THE UPPER 70S...EXCEPT ALONG
THE LAKE SHORE WHERE THE LAKE BREEZE WILL KEEP HIGH TEMPS IN THE
MID 70S.

SHOWERS AND STORMS DISSIPATE THIS EVENING WITH LIGHT SOUTHWEST WINDS
EXPECTED OVERNIGHT.  SKIES SHOULD CLEAR OUT NICELY SO EXPECTING MIN
TEMPS TO APPROACH THE DEWPOINTS. SO LOOKING AT LOWS IN THE UPPER 50S
IN THE OUTLYING AREAS...BUT IN THE LOW 60S DOWNTOWN.

JEE

THURSDAY THROUGH SATURDAY...

THE AREA REMAINS ON THE SOUTHWEST SIDE OF THE EASTERN CANADIAN
UPPER LONG WAVE TROUGH THROUGH THE END OF THE WEEK WITH LITTLE
CHANGE IN THE WEATHER PATTERN. AS IS TYPICALLY THE CASE WITH SUCH
AN ESTABLISHED LONG WAVE...MINOR PERTURBATIONS WILL TRAVERSE
DOWN THE BACK SIDE OF THE TROUGH OVER THE WESTERN GREAT
LAKES. EACH OF THESE LOOK TO BRING SUBTLE ENHANCEMENT TO LOW-
LEVEL CONVERGENCE AND KEEP COOL AIR ALOFT FOR ELONGATED CAPE
PROFILES NEAR PEAK HEATING. ALL IN ALL THESE CONTINUE TO PRESENT
MAINLY AFTERNOON AND EARLY EVENING SCATTERED SHOWER/STORM CHANCES.
THERE CONTINUES FAIR MODEL AGREEMENT ON BRINGING AN UPPER/MID
LEVEL SPEED MAX AND AN ASSOCIATED WAVE SOUTHWARD FOR BETTER
COVERAGE OF AFTERNOON SHOWERS/STORMS. BOTH THE SREF AND GEFS
SUPPORT HIGHER POPS OVER A GOOD AMOUNT OF THE AREA AND WHILE THE
MAGNITUDES OF BOTH MAY BE EXTREME /70 PERCENT PLUS/...THE IDEA OF
SCATTERED COVERAGE MORE SO THAN TODAY AND THURSDAY SEEMS LIKELY.
THE ASSOCIATED SURFACE FRONT HANGS UP OVER THE EASTERN FORECAST
AREA. THE LAKE BREEZE WILL CONTINUE TO ALSO BE A FOCUS FOR SHOWERS
AND STORMS...SO DO HAVE A LITTLE HIGHER POPS IN THE NORTHEAST
FORECAST AREA. VERY SLIGHT TEMPERATURE MODERATION IS EXPECTED
THROUGH THIS TIME.

EARLY NEXT WEEK...
HIGH PRESSURE LOOKS TO PREVAIL SATURDAY NIGHT THROUGH THE LATTER
HALF OF THE WEEKEND. THE UPPER LEVEL PATTERN LOOKS TO FLATTEN
SOMEWHAT WITH A QUICK MOVING SYSTEM NORTH OF THE GREAT LAKES
ADVERTISED EARLY NEXT WEEK BY GUIDANCE. THIS LOOKS TO STEER A COOL
FRONT INTO THE REGION WITH LARGE DISCREPANCY ON TIMING AND JUST
HOW FAR SOUTH THIS REACHES. HAVE NOT MADE ANY CHANGES TO A WELL-
VERIFYING BLEND OF GUIDANCE BESIDES INCHING UP TEMPS A COUPLE
DEGREES ON MONDAY AHEAD OF THIS COOL FRONTAL FEATURE.

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* LAKE BREEZE EXPECTED WITH WINDS SHIFTING E-NE ARND 10 KT.

* SCT SHRA THIS AFTN AND EVENING. A FEW TSRA ALSO PSBL.

JEE/KB

//DISCUSSION...UPDATED 12Z...

A WEAK COLD FRONT IS PUSHING SOUTH DOWN THE LAKE THIS MORNING AND
IT WILL STALL OUT JUST SOUTH OF THE TERMINALS. WINDS WILL BECOME
NORTHWEST AT 9 KT BEHIND THE FRONT. A LAKE BREEZE IS EXPECTED
TODAY AND IT WILL IMPACT ORD...MDW...AND GYY. NOT SURE IF THE
BREEZE WILL MAKE IT TO DPA SO KEPT A NW WIND AT DPA. WINDS WILL
SHIFT TO NE ARND 10 KT BEHIND THE LAKE BREEZE.

LIKE YESTERDAY...THE LAKE BREEZE WILL BE THE FOCUS FOR SCATTERED
SHOWERS AND A FEW ISOLATED THUNDERSTORMS. NOT EXPECTING AS MANY
THUNDERSTORMS AS YESTERDAY...BUT ANY THUNDERSTORMS THAT DO FORM
WILL HAVE STRONG DOWNDRAFTS AND PRODUCE GUSTY WINDS UP TO 35 KT.

WINDS BACK TO WEST IN THE EVENING AND REMAIN WEST THROUGH THE REST
OF THE PERIOD.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* HIGH CONFIDENCE IN LAKE BREEZE...MEDIUM-HIGH CONFIDENCE IN
  TIMING.

* MEDIUM-HIGH CONFIDENCE IN SHRA DEVELOPMENT AND COVERAGE...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE/KB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SCHC TSRA EARLY IN THE EVENING...SCHC SHRA LATE
IN THE EVENING.

FRIDAY...CHC SHRA WITH A CHC OF TSRA IN THE AFTN.

SATURDAY...SCHC SHRA IN THE MORNING...CHC OF TSRA IN THE AFTN.

SUNDAY...VFR.

MONDAY...CHC TSRA OVERNIGHT.

TUESDAY...CHC TSRA.

JEE

&&

.MARINE...
255 AM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE WITH A WEAK COLD
FRONT/UPPER LEVEL WAVE MOVING DOWN THE LAKE EARLY THIS MORNING.
WINDS BECOME NORTH AROUND 10 KT BEHIND THE FRONT. HIGH PRESSURE
OVER THE PLAINS ATTEMPTS TO SPREAD EAST TODAY LEADING TO A
CONTINUED VERY WEAK PRESSURE GRADIENT. ONSHORE FLOW IS EXPECTED
ACROSS NEARSHORE AREAS LEADING TO VARIABLE WINDS 10 KT OR LESS AT
TIMES OVER THE OPEN WATERS. WINDS BECOME MORE UNIFORM THIS EVENING
WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY MORNING. A
COUPLE MORE WEAK COOL FRONTS ARE EXPECTED BY WEEKS END...AT THIS
TIME THURSDAY NIGHT AND AGAIN FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS AND SOME STORMS MAINLY DRIVEN BY THE HEATING OF
THE DAY OVER LAND. SOME OF THESE COULD BE ABLE TO MOVE INTO
NEARSHORE AREAS ON THE WESTERN SIDE OF THE LAKE AS SEEN OVER WI/IL
SHORES LAST EVENING...AND PROFILES OVER LAND DO SUPPORT SOME QUICK
RACING OUTFLOWS/GUST FRONTS FROM SHOWERS THE NEXT FEW DAYS...SO
SOMETHING FOR NEARSHORE MARINERS TO KEEP SOME TABS ON DESPITE THE
MAINLY QUIET WIND/WAVE REGIME.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KILX 301454
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
954 AM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 954 AM CDT Wed Jul 30 2014

High pressure extending from the Northern Plains to the Ohio
River Valley is providing mostly sunny and cool conditions to
central Illinois this morning. Main question will be whether or
not any showers will develop within the cyclonic flow pattern
aloft. 14z/9am water vapor imagery shows deep upper low spinning
over Hudson Bay, with short-wave trough rotating around this
feature across southern Michigan. The influence of this wave will
likely remain NE of Illinois today, with scattered showers/thunder
developing across southern Michigan/Northern Indiana this
afternoon. Upper support will be weaker further W/SW, so am not
expecting much precip at all in Illinois. HRRR suggests isolated
showers may fire after 19z, mainly across northern Illinois.
Meanwhile, the NAM12 is completely dry. Have therefore scaled back
PoPs today, with only an isolated shower mention along/north of
I-74 this afternoon. Have also removed evening showers and gone
with a mostly clear forecast for tonight. Zone update has already
been issued.

Barnes
&&

.AVIATION...
ISSUED 600 AM CDT Wed Jul 30 2014

VFR conditions expected at all central Illinois TAF sites for the
next 24hrs. Mostly clear skies will continue until late
morning then scattered cloud cover at 4-5 kft MSL will develop
with daytime heating. Isolated light afternoon showers are
possible...mainly KMTO-KGBG northward...however any MVFR
cigs/vsbys unlikely. After 00Z...any shower activity/cloud cover
diminishing. Winds increasing to WNW7-10 kts by 15Z...becoming
light and variable by 00Z.

Onton
&&

.PREV DISCUSSION...
ISSUED 317 AM CDT Wed Jul 30 2014
Forecast and overall atmospheric pattern slow to change right now
as an upper low remains parked over the southern tip of Hudson
Bay...with the trof dominating the eastern half of the CONUS. 500
mb ridge over the west, and sfc high pressure building into the
Midwest with northwesterly flow aloft. Forecast driven by slowly
warming temperatures, still below normal for late July, light
winds, and afternoon showers. Next chance for a slightly more
substantial chance for thunderstorms arrives on Friday, with a
wave diving into the upper trof and helping to enhance the
dynamics. Overall, very little in the forecast warranting more
than a chance/scattered mention, and not many changes expected
until the pattern breaks later in the weekend.

SHORT TERM...Today and tomorrow...
Partly cloudy afternoon skies with slight chance for some
afternoon showers and iso thunder... with the better chances to
the northeast. High temperatures upper 70s/low 80s...and overnight
lows dropping to upper 50s/near 60 with mostly clear skies. Upper
low anchored over southeastern Canada keeps the weather in a
pretty stagnant pattern and below normal temps in the Midwest.

LONG TERM...Friday through Tuesday...
Best chances for showers and thunderstorms moving in for Friday...
as a wave rotates through the trof and enhances chances for
scattered showers and thunderstorms. Models pretty consistent with
this feature...though coverage is not expected to be widespread
just yet. High pressure dominating into the weekend as the sfc
ridge axis moves into the region. Winds remain light and variable
and dry forecast as the upper trof finally starts to progress
across into the NE. Chances for more significant weather starting
to return Tues/Wed as a more active and progressive flow sets up
across the country.

HJS

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KILX 301454
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
954 AM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 954 AM CDT Wed Jul 30 2014

High pressure extending from the Northern Plains to the Ohio
River Valley is providing mostly sunny and cool conditions to
central Illinois this morning. Main question will be whether or
not any showers will develop within the cyclonic flow pattern
aloft. 14z/9am water vapor imagery shows deep upper low spinning
over Hudson Bay, with short-wave trough rotating around this
feature across southern Michigan. The influence of this wave will
likely remain NE of Illinois today, with scattered showers/thunder
developing across southern Michigan/Northern Indiana this
afternoon. Upper support will be weaker further W/SW, so am not
expecting much precip at all in Illinois. HRRR suggests isolated
showers may fire after 19z, mainly across northern Illinois.
Meanwhile, the NAM12 is completely dry. Have therefore scaled back
PoPs today, with only an isolated shower mention along/north of
I-74 this afternoon. Have also removed evening showers and gone
with a mostly clear forecast for tonight. Zone update has already
been issued.

Barnes
&&

.AVIATION...
ISSUED 600 AM CDT Wed Jul 30 2014

VFR conditions expected at all central Illinois TAF sites for the
next 24hrs. Mostly clear skies will continue until late
morning then scattered cloud cover at 4-5 kft MSL will develop
with daytime heating. Isolated light afternoon showers are
possible...mainly KMTO-KGBG northward...however any MVFR
cigs/vsbys unlikely. After 00Z...any shower activity/cloud cover
diminishing. Winds increasing to WNW7-10 kts by 15Z...becoming
light and variable by 00Z.

Onton
&&

.PREV DISCUSSION...
ISSUED 317 AM CDT Wed Jul 30 2014
Forecast and overall atmospheric pattern slow to change right now
as an upper low remains parked over the southern tip of Hudson
Bay...with the trof dominating the eastern half of the CONUS. 500
mb ridge over the west, and sfc high pressure building into the
Midwest with northwesterly flow aloft. Forecast driven by slowly
warming temperatures, still below normal for late July, light
winds, and afternoon showers. Next chance for a slightly more
substantial chance for thunderstorms arrives on Friday, with a
wave diving into the upper trof and helping to enhance the
dynamics. Overall, very little in the forecast warranting more
than a chance/scattered mention, and not many changes expected
until the pattern breaks later in the weekend.

SHORT TERM...Today and tomorrow...
Partly cloudy afternoon skies with slight chance for some
afternoon showers and iso thunder... with the better chances to
the northeast. High temperatures upper 70s/low 80s...and overnight
lows dropping to upper 50s/near 60 with mostly clear skies. Upper
low anchored over southeastern Canada keeps the weather in a
pretty stagnant pattern and below normal temps in the Midwest.

LONG TERM...Friday through Tuesday...
Best chances for showers and thunderstorms moving in for Friday...
as a wave rotates through the trof and enhances chances for
scattered showers and thunderstorms. Models pretty consistent with
this feature...though coverage is not expected to be widespread
just yet. High pressure dominating into the weekend as the sfc
ridge axis moves into the region. Winds remain light and variable
and dry forecast as the upper trof finally starts to progress
across into the NE. Chances for more significant weather starting
to return Tues/Wed as a more active and progressive flow sets up
across the country.

HJS

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$







000
FXUS63 KLOT 301357
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
857 AM CDT WED JUL 30 2014

.DISCUSSION...
315 AM CDT

SYNOPSIS...TODAY WILL BE VERY SIMILAR TO YESTERDAY WITH A LAKE
BREEZE PUSHING INLAND.  SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL FORM ALONG THE BOUNDARY. THERE ARE CHANCES FOR AFTERNOON
THUNDERSTORMS THROUGH SATURDAY WITH THE BETTER CHANCES FRIDAY AND
SATURDAY.  ADDITIONAL THUNDERSTORMS ARE POSSIBLE EARLY NEXT WEEK.
TEMPERATURES SLOWLY RISE THROUGH EARLY NEXT WEEK WITH MID 80 HIGH
TEMPS POSSIBLE MONDAY.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS STILL PARKED OVER JAMES BAY. A SHORT WAVE
TROUGH/COLD FRONT ASSOCIATED WITH THE LOW IS OVER CENTRAL WI AND IT
WILL SLIDE DOWN THE LAKE THROUGH THIS MORNING. THE FRONT LOSES STEAM
THIS AFTERNOON AND STALLS OVER NORTHERN IL AND IN.

A LAKE BREEZE IS ALSO EXPECTED TODAY SO THERE SHOULD BE ADEQUATE
FORCING FOR SHOWERS AND A FEW STORMS BETWEEN THE LAKE BREEZE AND
STALLED OUT COLD FRONT.  CAPE WILL ONCE AGAIN BE LIMITED TO BELOW
500 J/KG SO NOT EXPECTING A TON OF THUNDERSTORM ACTIVITY. UPPER
LEVEL TEMPS AND SURFACE TEMPS WILL BE A BIT COOLER TODAY SO THINKING
THAT WILL ALSO LIMIT INSTABILITY.  ANY STORMS THAT DO FORM WILL NOT
BE SEVERE...BUT MAY BE DOWNDRAFT DRIVEN PRODUCING GUSTY WINDS
LIKE YESTERDAY. HIGH TEMPS WILL BE IN THE UPPER 70S...EXCEPT ALONG
THE LAKE SHORE WHERE THE LAKE BREEZE WILL KEEP HIGH TEMPS IN THE
MID 70S.

SHOWERS AND STORMS DISSIPATE THIS EVENING WITH LIGHT SOUTHWEST WINDS
EXPECTED OVERNIGHT.  SKIES SHOULD CLEAR OUT NICELY SO EXPECTING MIN
TEMPS TO APPROACH THE DEWPOINTS. SO LOOKING AT LOWS IN THE UPPER 50S
IN THE OUTLYING AREAS...BUT IN THE LOW 60S DOWNTOWN.

JEE

THURSDAY THROUGH SATURDAY...

THE AREA REMAINS ON THE SOUTHWEST SIDE OF THE EASTERN CANADIAN
UPPER LONG WAVE TROUGH THROUGH THE END OF THE WEEK WITH LITTLE
CHANGE IN THE WEATHER PATTERN. AS IS TYPICALLY THE CASE WITH SUCH
AN ESTABLISHED LONG WAVE...MINOR PERTURBATIONS WILL TRAVERSE
DOWN THE BACK SIDE OF THE TROUGH OVER THE WESTERN GREAT
LAKES. EACH OF THESE LOOK TO BRING SUBTLE ENHANCEMENT TO LOW-
LEVEL CONVERGENCE AND KEEP COOL AIR ALOFT FOR ELONGATED CAPE
PROFILES NEAR PEAK HEATING. ALL IN ALL THESE CONTINUE TO PRESENT
MAINLY AFTERNOON AND EARLY EVENING SCATTERED SHOWER/STORM CHANCES.
THERE CONTINUES FAIR MODEL AGREEMENT ON BRINGING AN UPPER/MID
LEVEL SPEED MAX AND AN ASSOCIATED WAVE SOUTHWARD FOR BETTER
COVERAGE OF AFTERNOON SHOWERS/STORMS. BOTH THE SREF AND GEFS
SUPPORT HIGHER POPS OVER A GOOD AMOUNT OF THE AREA AND WHILE THE
MAGNITUDES OF BOTH MAY BE EXTREME /70 PERCENT PLUS/...THE IDEA OF
SCATTERED COVERAGE MORE SO THAN TODAY AND THURSDAY SEEMS LIKELY.
THE ASSOCIATED SURFACE FRONT HANGS UP OVER THE EASTERN FORECAST
AREA. THE LAKE BREEZE WILL CONTINUE TO ALSO BE A FOCUS FOR SHOWERS
AND STORMS...SO DO HAVE A LITTLE HIGHER POPS IN THE NORTHEAST
FORECAST AREA. VERY SLIGHT TEMPERATURE MODERATION IS EXPECTED
THROUGH THIS TIME.

EARLY NEXT WEEK...
HIGH PRESSURE LOOKS TO PREVAIL SATURDAY NIGHT THROUGH THE LATTER
HALF OF THE WEEKEND. THE UPPER LEVEL PATTERN LOOKS TO FLATTEN
SOMEWHAT WITH A QUICK MOVING SYSTEM NORTH OF THE GREAT LAKES
ADVERTISED EARLY NEXT WEEK BY GUIDANCE. THIS LOOKS TO STEER A COOL
FRONT INTO THE REGION WITH LARGE DISCREPANCY ON TIMING AND JUST
HOW FAR SOUTH THIS REACHES. HAVE NOT MADE ANY CHANGES TO A WELL-
VERIFYING BLEND OF GUIDANCE BESIDES INCHING UP TEMPS A COUPLE
DEGREES ON MONDAY AHEAD OF THIS COOL FRONTAL FEATURE.

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 14Z...

* LAKE BREEZE EXPECTED WITH WINDS SHIFTING E-NE ARND 10 KT.

* SCT SHRA THIS AFTN AND EVENING. A FEW TSRA ALSO PSBL.

JEE/KB

//DISCUSSION...UPDATED 12Z...

A WEAK COLD FRONT IS PUSHING SOUTH DOWN THE LAKE THIS MORNING AND
IT WILL STALL OUT JUST SOUTH OF THE TERMINALS. WINDS WILL BECOME
NORTHWEST AT 9 KT BEHIND THE FRONT. A LAKE BREEZE IS EXPECTED
TODAY AND IT WILL IMPACT ORD...MDW...AND GYY. NOT SURE IF THE
BREEZE WILL MAKE IT TO DPA SO KEPT A NW WIND AT DPA. WINDS WILL
SHIFT TO NE ARND 10 KT BEHIND THE LAKE BREEZE.

LIKE YESTERDAY...THE LAKE BREEZE WILL BE THE FOCUS FOR SCATTERED
SHOWERS AND A FEW ISOLATED THUNDERSTORMS. NOT EXPECTING AS MANY
THUNDERSTORMS AS YESTERDAY...BUT ANY THUNDERSTORMS THAT DO FORM
WILL HAVE STRONG DOWNDRAFTS AND PRODUCE GUSTY WINDS UP TO 35 KT.

WINDS BACK TO WEST IN THE EVENING AND REMAIN WEST THROUGH THE REST
OF THE PERIOD.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* HIGH CONFIDENCE IN LAKE BREEZE...MEDIUM-HIGH CONFIDENCE IN
  TIMING.

* MEDIUM-HIGH CONFIDENCE IN SHRA DEVELOPMENT AND COVERAGE...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE/KB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SCHC TSRA EARLY IN THE EVENING...SCHC SHRA LATE
IN THE EVENING.

FRIDAY...CHC SHRA WITH A CHC OF TSRA IN THE AFTN.

SATURDAY...SCHC SHRA IN THE MORNING...CHC OF TSRA IN THE AFTN.

SUNDAY...VFR.

MONDAY...CHC TSRA OVERNIGHT.

TUESDAY...CHC TSRA.

JEE

&&

.MARINE...
255 AM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE WITH A WEAK COLD
FRONT/UPPER LEVEL WAVE MOVING DOWN THE LAKE EARLY THIS MORNING.
WINDS BECOME NORTH AROUND 10 KT BEHIND THE FRONT. HIGH PRESSURE
OVER THE PLAINS ATTEMPTS TO SPREAD EAST TODAY LEADING TO A
CONTINUED VERY WEAK PRESSURE GRADIENT. ONSHORE FLOW IS EXPECTED
ACROSS NEARSHORE AREAS LEADING TO VARIABLE WINDS 10 KT OR LESS AT
TIMES OVER THE OPEN WATERS. WINDS BECOME MORE UNIFORM THIS EVENING
WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY MORNING. A
COUPLE MORE WEAK COOL FRONTS ARE EXPECTED BY WEEKS END...AT THIS
TIME THURSDAY NIGHT AND AGAIN FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS AND SOME STORMS MAINLY DRIVEN BY THE HEATING OF
THE DAY OVER LAND. SOME OF THESE COULD BE ABLE TO MOVE INTO
NEARSHORE AREAS ON THE WESTERN SIDE OF THE LAKE AS SEEN OVER WI/IL
SHORES LAST EVENING...AND PROFILES OVER LAND DO SUPPORT SOME QUICK
RACING OUTFLOWS/GUST FRONTS FROM SHOWERS THE NEXT FEW DAYS...SO
SOMETHING FOR NEARSHORE MARINERS TO KEEP SOME TABS ON DESPITE THE
MAINLY QUIET WIND/WAVE REGIME.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 301357
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
857 AM CDT WED JUL 30 2014

.DISCUSSION...
315 AM CDT

SYNOPSIS...TODAY WILL BE VERY SIMILAR TO YESTERDAY WITH A LAKE
BREEZE PUSHING INLAND.  SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL FORM ALONG THE BOUNDARY. THERE ARE CHANCES FOR AFTERNOON
THUNDERSTORMS THROUGH SATURDAY WITH THE BETTER CHANCES FRIDAY AND
SATURDAY.  ADDITIONAL THUNDERSTORMS ARE POSSIBLE EARLY NEXT WEEK.
TEMPERATURES SLOWLY RISE THROUGH EARLY NEXT WEEK WITH MID 80 HIGH
TEMPS POSSIBLE MONDAY.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS STILL PARKED OVER JAMES BAY. A SHORT WAVE
TROUGH/COLD FRONT ASSOCIATED WITH THE LOW IS OVER CENTRAL WI AND IT
WILL SLIDE DOWN THE LAKE THROUGH THIS MORNING. THE FRONT LOSES STEAM
THIS AFTERNOON AND STALLS OVER NORTHERN IL AND IN.

A LAKE BREEZE IS ALSO EXPECTED TODAY SO THERE SHOULD BE ADEQUATE
FORCING FOR SHOWERS AND A FEW STORMS BETWEEN THE LAKE BREEZE AND
STALLED OUT COLD FRONT.  CAPE WILL ONCE AGAIN BE LIMITED TO BELOW
500 J/KG SO NOT EXPECTING A TON OF THUNDERSTORM ACTIVITY. UPPER
LEVEL TEMPS AND SURFACE TEMPS WILL BE A BIT COOLER TODAY SO THINKING
THAT WILL ALSO LIMIT INSTABILITY.  ANY STORMS THAT DO FORM WILL NOT
BE SEVERE...BUT MAY BE DOWNDRAFT DRIVEN PRODUCING GUSTY WINDS
LIKE YESTERDAY. HIGH TEMPS WILL BE IN THE UPPER 70S...EXCEPT ALONG
THE LAKE SHORE WHERE THE LAKE BREEZE WILL KEEP HIGH TEMPS IN THE
MID 70S.

SHOWERS AND STORMS DISSIPATE THIS EVENING WITH LIGHT SOUTHWEST WINDS
EXPECTED OVERNIGHT.  SKIES SHOULD CLEAR OUT NICELY SO EXPECTING MIN
TEMPS TO APPROACH THE DEWPOINTS. SO LOOKING AT LOWS IN THE UPPER 50S
IN THE OUTLYING AREAS...BUT IN THE LOW 60S DOWNTOWN.

JEE

THURSDAY THROUGH SATURDAY...

THE AREA REMAINS ON THE SOUTHWEST SIDE OF THE EASTERN CANADIAN
UPPER LONG WAVE TROUGH THROUGH THE END OF THE WEEK WITH LITTLE
CHANGE IN THE WEATHER PATTERN. AS IS TYPICALLY THE CASE WITH SUCH
AN ESTABLISHED LONG WAVE...MINOR PERTURBATIONS WILL TRAVERSE
DOWN THE BACK SIDE OF THE TROUGH OVER THE WESTERN GREAT
LAKES. EACH OF THESE LOOK TO BRING SUBTLE ENHANCEMENT TO LOW-
LEVEL CONVERGENCE AND KEEP COOL AIR ALOFT FOR ELONGATED CAPE
PROFILES NEAR PEAK HEATING. ALL IN ALL THESE CONTINUE TO PRESENT
MAINLY AFTERNOON AND EARLY EVENING SCATTERED SHOWER/STORM CHANCES.
THERE CONTINUES FAIR MODEL AGREEMENT ON BRINGING AN UPPER/MID
LEVEL SPEED MAX AND AN ASSOCIATED WAVE SOUTHWARD FOR BETTER
COVERAGE OF AFTERNOON SHOWERS/STORMS. BOTH THE SREF AND GEFS
SUPPORT HIGHER POPS OVER A GOOD AMOUNT OF THE AREA AND WHILE THE
MAGNITUDES OF BOTH MAY BE EXTREME /70 PERCENT PLUS/...THE IDEA OF
SCATTERED COVERAGE MORE SO THAN TODAY AND THURSDAY SEEMS LIKELY.
THE ASSOCIATED SURFACE FRONT HANGS UP OVER THE EASTERN FORECAST
AREA. THE LAKE BREEZE WILL CONTINUE TO ALSO BE A FOCUS FOR SHOWERS
AND STORMS...SO DO HAVE A LITTLE HIGHER POPS IN THE NORTHEAST
FORECAST AREA. VERY SLIGHT TEMPERATURE MODERATION IS EXPECTED
THROUGH THIS TIME.

EARLY NEXT WEEK...
HIGH PRESSURE LOOKS TO PREVAIL SATURDAY NIGHT THROUGH THE LATTER
HALF OF THE WEEKEND. THE UPPER LEVEL PATTERN LOOKS TO FLATTEN
SOMEWHAT WITH A QUICK MOVING SYSTEM NORTH OF THE GREAT LAKES
ADVERTISED EARLY NEXT WEEK BY GUIDANCE. THIS LOOKS TO STEER A COOL
FRONT INTO THE REGION WITH LARGE DISCREPANCY ON TIMING AND JUST
HOW FAR SOUTH THIS REACHES. HAVE NOT MADE ANY CHANGES TO A WELL-
VERIFYING BLEND OF GUIDANCE BESIDES INCHING UP TEMPS A COUPLE
DEGREES ON MONDAY AHEAD OF THIS COOL FRONTAL FEATURE.

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 14Z...

* LAKE BREEZE EXPECTED WITH WINDS SHIFTING E-NE ARND 10 KT.

* SCT SHRA THIS AFTN AND EVENING. A FEW TSRA ALSO PSBL.

JEE/KB

//DISCUSSION...UPDATED 12Z...

A WEAK COLD FRONT IS PUSHING SOUTH DOWN THE LAKE THIS MORNING AND
IT WILL STALL OUT JUST SOUTH OF THE TERMINALS. WINDS WILL BECOME
NORTHWEST AT 9 KT BEHIND THE FRONT. A LAKE BREEZE IS EXPECTED
TODAY AND IT WILL IMPACT ORD...MDW...AND GYY. NOT SURE IF THE
BREEZE WILL MAKE IT TO DPA SO KEPT A NW WIND AT DPA. WINDS WILL
SHIFT TO NE ARND 10 KT BEHIND THE LAKE BREEZE.

LIKE YESTERDAY...THE LAKE BREEZE WILL BE THE FOCUS FOR SCATTERED
SHOWERS AND A FEW ISOLATED THUNDERSTORMS. NOT EXPECTING AS MANY
THUNDERSTORMS AS YESTERDAY...BUT ANY THUNDERSTORMS THAT DO FORM
WILL HAVE STRONG DOWNDRAFTS AND PRODUCE GUSTY WINDS UP TO 35 KT.

WINDS BACK TO WEST IN THE EVENING AND REMAIN WEST THROUGH THE REST
OF THE PERIOD.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* HIGH CONFIDENCE IN LAKE BREEZE...MEDIUM-HIGH CONFIDENCE IN
  TIMING.

* MEDIUM-HIGH CONFIDENCE IN SHRA DEVELOPMENT AND COVERAGE...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE/KB

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SCHC TSRA EARLY IN THE EVENING...SCHC SHRA LATE
IN THE EVENING.

FRIDAY...CHC SHRA WITH A CHC OF TSRA IN THE AFTN.

SATURDAY...SCHC SHRA IN THE MORNING...CHC OF TSRA IN THE AFTN.

SUNDAY...VFR.

MONDAY...CHC TSRA OVERNIGHT.

TUESDAY...CHC TSRA.

JEE

&&

.MARINE...
255 AM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE WITH A WEAK COLD
FRONT/UPPER LEVEL WAVE MOVING DOWN THE LAKE EARLY THIS MORNING.
WINDS BECOME NORTH AROUND 10 KT BEHIND THE FRONT. HIGH PRESSURE
OVER THE PLAINS ATTEMPTS TO SPREAD EAST TODAY LEADING TO A
CONTINUED VERY WEAK PRESSURE GRADIENT. ONSHORE FLOW IS EXPECTED
ACROSS NEARSHORE AREAS LEADING TO VARIABLE WINDS 10 KT OR LESS AT
TIMES OVER THE OPEN WATERS. WINDS BECOME MORE UNIFORM THIS EVENING
WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY MORNING. A
COUPLE MORE WEAK COOL FRONTS ARE EXPECTED BY WEEKS END...AT THIS
TIME THURSDAY NIGHT AND AGAIN FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS AND SOME STORMS MAINLY DRIVEN BY THE HEATING OF
THE DAY OVER LAND. SOME OF THESE COULD BE ABLE TO MOVE INTO
NEARSHORE AREAS ON THE WESTERN SIDE OF THE LAKE AS SEEN OVER WI/IL
SHORES LAST EVENING...AND PROFILES OVER LAND DO SUPPORT SOME QUICK
RACING OUTFLOWS/GUST FRONTS FROM SHOWERS THE NEXT FEW DAYS...SO
SOMETHING FOR NEARSHORE MARINERS TO KEEP SOME TABS ON DESPITE THE
MAINLY QUIET WIND/WAVE REGIME.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 301106
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
606 AM CDT WED JUL 30 2014

.DISCUSSION...
315 AM CDT

SYNOPSIS...TODAY WILL BE VERY SIMILAR TO YESTERDAY WITH A LAKE
BREEZE PUSHING INLAND.  SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL FORM ALONG THE BOUNDARY. THERE ARE CHANCES FOR AFTERNOON
THUNDERSTORMS THROUGH SATURDAY WITH THE BETTER CHANCES FRIDAY AND
SATURDAY.  ADDITIONAL THUNDERSTORMS ARE POSSIBLE EARLY NEXT WEEK.
TEMPERATURES SLOWLY RISE THROUGH EARLY NEXT WEEK WITH MID 80 HIGH
TEMPS POSSIBLE MONDAY.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS STILL PARKED OVER JAMES BAY. A SHORT WAVE
TROUGH/COLD FRONT ASSOCIATED WITH THE LOW IS OVER CENTRAL WI AND IT
WILL SLIDE DOWN THE LAKE THROUGH THIS MORNING. THE FRONT LOSES STEAM
THIS AFTERNOON AND STALLS OVER NORTHERN IL AND IN.

A LAKE BREEZE IS ALSO EXPECTED TODAY SO THERE SHOULD BE ADEQUATE
FORCING FOR SHOWERS AND A FEW STORMS BETWEEN THE LAKE BREEZE AND
STALLED OUT COLD FRONT.  CAPE WILL ONCE AGAIN BE LIMITED TO BELOW
500 J/KG SO NOT EXPECTING A TON OF THUNDERSTORM ACTIVITY. UPPER
LEVEL TEMPS AND SURFACE TEMPS WILL BE A BIT COOLER TODAY SO THINKING
THAT WILL ALSO LIMIT INSTABILITY.  ANY STORMS THAT DO FORM WILL NOT
BE SEVERE...BUT MAY BE DOWNDRAFT DRIVEN PRODUCING GUSTY WINDS
LIKE YESTERDAY. HIGH TEMPS WILL BE IN THE UPPER 70S...EXCEPT ALONG
THE LAKE SHORE WHERE THE LAKE BREEZE WILL KEEP HIGH TEMPS IN THE
MID 70S.

SHOWERS AND STORMS DISSIPATE THIS EVENING WITH LIGHT SOUTHWEST WINDS
EXPECTED OVERNIGHT.  SKIES SHOULD CLEAR OUT NICELY SO EXPECTING MIN
TEMPS TO APPROACH THE DEWPOINTS. SO LOOKING AT LOWS IN THE UPPER 50S
IN THE OUTLYING AREAS...BUT IN THE LOW 60S DOWNTOWN.

JEE

THURSDAY THROUGH SATURDAY...

THE AREA REMAINS ON THE SOUTHWEST SIDE OF THE EASTERN CANADIAN
UPPER LONG WAVE TROUGH THROUGH THE END OF THE WEEK WITH LITTLE
CHANGE IN THE WEATHER PATTERN. AS IS TYPICALLY THE CASE WITH SUCH
AN ESTABLISHED LONG WAVE...MINOR PERTURBATIONS WILL TRAVERSE
DOWN THE BACK SIDE OF THE TROUGH OVER THE WESTERN GREAT
LAKES. EACH OF THESE LOOK TO BRING SUBTLE ENHANCEMENT TO LOW-
LEVEL CONVERGENCE AND KEEP COOL AIR ALOFT FOR ELONGATED CAPE
PROFILES NEAR PEAK HEATING. ALL IN ALL THESE CONTINUE TO PRESENT
MAINLY AFTERNOON AND EARLY EVENING SCATTERED SHOWER/STORM CHANCES.
THERE CONTINUES FAIR MODEL AGREEMENT ON BRINGING AN UPPER/MID
LEVEL SPEED MAX AND AN ASSOCIATED WAVE SOUTHWARD FOR BETTER
COVERAGE OF AFTERNOON SHOWERS/STORMS. BOTH THE SREF AND GEFS
SUPPORT HIGHER POPS OVER A GOOD AMOUNT OF THE AREA AND WHILE THE
MAGNITUDES OF BOTH MAY BE EXTREME /70 PERCENT PLUS/...THE IDEA OF
SCATTERED COVERAGE MORE SO THAN TODAY AND THURSDAY SEEMS LIKELY.
THE ASSOCIATED SURFACE FRONT HANGS UP OVER THE EASTERN FORECAST
AREA. THE LAKE BREEZE WILL CONTINUE TO ALSO BE A FOCUS FOR SHOWERS
AND STORMS...SO DO HAVE A LITTLE HIGHER POPS IN THE NORTHEAST
FORECAST AREA. VERY SLIGHT TEMPERATURE MODERATION IS EXPECTED
THROUGH THIS TIME.

EARLY NEXT WEEK...
HIGH PRESSURE LOOKS TO PREVAIL SATURDAY NIGHT THROUGH THE LATTER
HALF OF THE WEEKEND. THE UPPER LEVEL PATTERN LOOKS TO FLATTEN
SOMEWHAT WITH A QUICK MOVING SYSTEM NORTH OF THE GREAT LAKES
ADVERTISED EARLY NEXT WEEK BY GUIDANCE. THIS LOOKS TO STEER A COOL
FRONT INTO THE REGION WITH LARGE DISCREPANCY ON TIMING AND JUST
HOW FAR SOUTH THIS REACHES. HAVE NOT MADE ANY CHANGES TO A WELL-
VERIFYING BLEND OF GUIDANCE BESIDES INCHING UP TEMPS A COUPLE
DEGREES ON MONDAY AHEAD OF THIS COOL FRONTAL FEATURE.

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* LAKE BREEZE EXPECTED WITH WINDS SHIFTING TO NE ARND 10 KT.

* SCT SHRA THIS AFTN AND EVENING. A FEW TSRA PSBL.

JEE

//DISCUSSION...UPDATED 12Z...

A WEAK COLD FRONT IS PUSHING SOUTH DOWN THE LAKE THIS MORNING AND
IT WILL STALL OUT JUST SOUTH OF THE TERMINALS. WINDS WILL BECOME
NORTHWEST AT 9 KT BEHIND THE FRONT. A LAKE BREEZE IS EXPECTED
TODAY AND IT WILL IMPACT ORD...MDW...AND GYY. NOT SURE IF THE
BREEZE WILL MAKE IT TO DPA SO KEPT A NW WIND AT DPA. WINDS WILL
SHIFT TO NE ARND 10 KT BEHIND THE LAKE BREEZE.

LIKE YESTERDAY...THE LAKE BREEZE WILL BE THE FOCUS FOR SCATTERED
SHOWERS AND A FEW ISOLATED THUNDERSTORMS. NOT EXPECTING AS MANY
THUNDERSTORMS AS YESTERDAY...BUT ANY THUNDERSTORMS THAT DO FORM
WILL HAVE STRONG DOWNDRAFTS AND PRODUCE GUSTY WINDS UP TO 35 KT.

WINDS BACK TO WEST IN THE EVENING AND REMAIN WEST THROUGH THE REST
OF THE PERIOD.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* HIGH CONFIDENCE IN LAKE BREEZE...MEDIUM-HIGH CONFIDENCE IN
  TIMING.

* MEDIUM-HIGH CONFIDENCE IN SHRA DEVELOPMENT AND COVERAGE...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SCHC TSRA EARLY IN THE EVENING...SCHC SHRA LATE
IN THE EVENING.

FRIDAY...CHC SHRA WITH A CHC OF TSRA IN THE AFTN.

SATURDAY...SCHC SHRA IN THE MORNING...CHC OF TSRA IN THE AFTN.

SUNDAY...VFR.

MONDAY...CHC TSRA OVERNIGHT.

TUESDAY...CHC TSRA.

JEE

&&

.MARINE...
255 AM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE WITH A WEAK COLD
FRONT/UPPER LEVEL WAVE MOVING DOWN THE LAKE EARLY THIS MORNING.
WINDS BECOME NORTH AROUND 10 KT BEHIND THE FRONT. HIGH PRESSURE
OVER THE PLAINS ATTEMPTS TO SPREAD EAST TODAY LEADING TO A
CONTINUED VERY WEAK PRESSURE GRADIENT. ONSHORE FLOW IS EXPECTED
ACROSS NEARSHORE AREAS LEADING TO VARIABLE WINDS 10 KT OR LESS AT
TIMES OVER THE OPEN WATERS. WINDS BECOME MORE UNIFORM THIS EVENING
WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY MORNING. A
COUPLE MORE WEAK COOL FRONTS ARE EXPECTED BY WEEKS END...AT THIS
TIME THURSDAY NIGHT AND AGAIN FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS AND SOME STORMS MAINLY DRIVEN BY THE HEATING OF
THE DAY OVER LAND. SOME OF THESE COULD BE ABLE TO MOVE INTO
NEARSHORE AREAS ON THE WESTERN SIDE OF THE LAKE AS SEEN OVER WI/IL
SHORES LAST EVENING...AND PROFILES OVER LAND DO SUPPORT SOME QUICK
RACING OUTFLOWS/GUST FRONTS FROM SHOWERS THE NEXT FEW DAYS...SO
SOMETHING FOR NEARSHORE MARINERS TO KEEP SOME TABS ON DESPITE THE
MAINLY QUIET WIND/WAVE REGIME.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 301106
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
606 AM CDT WED JUL 30 2014

.DISCUSSION...
315 AM CDT

SYNOPSIS...TODAY WILL BE VERY SIMILAR TO YESTERDAY WITH A LAKE
BREEZE PUSHING INLAND.  SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL FORM ALONG THE BOUNDARY. THERE ARE CHANCES FOR AFTERNOON
THUNDERSTORMS THROUGH SATURDAY WITH THE BETTER CHANCES FRIDAY AND
SATURDAY.  ADDITIONAL THUNDERSTORMS ARE POSSIBLE EARLY NEXT WEEK.
TEMPERATURES SLOWLY RISE THROUGH EARLY NEXT WEEK WITH MID 80 HIGH
TEMPS POSSIBLE MONDAY.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS STILL PARKED OVER JAMES BAY. A SHORT WAVE
TROUGH/COLD FRONT ASSOCIATED WITH THE LOW IS OVER CENTRAL WI AND IT
WILL SLIDE DOWN THE LAKE THROUGH THIS MORNING. THE FRONT LOSES STEAM
THIS AFTERNOON AND STALLS OVER NORTHERN IL AND IN.

A LAKE BREEZE IS ALSO EXPECTED TODAY SO THERE SHOULD BE ADEQUATE
FORCING FOR SHOWERS AND A FEW STORMS BETWEEN THE LAKE BREEZE AND
STALLED OUT COLD FRONT.  CAPE WILL ONCE AGAIN BE LIMITED TO BELOW
500 J/KG SO NOT EXPECTING A TON OF THUNDERSTORM ACTIVITY. UPPER
LEVEL TEMPS AND SURFACE TEMPS WILL BE A BIT COOLER TODAY SO THINKING
THAT WILL ALSO LIMIT INSTABILITY.  ANY STORMS THAT DO FORM WILL NOT
BE SEVERE...BUT MAY BE DOWNDRAFT DRIVEN PRODUCING GUSTY WINDS
LIKE YESTERDAY. HIGH TEMPS WILL BE IN THE UPPER 70S...EXCEPT ALONG
THE LAKE SHORE WHERE THE LAKE BREEZE WILL KEEP HIGH TEMPS IN THE
MID 70S.

SHOWERS AND STORMS DISSIPATE THIS EVENING WITH LIGHT SOUTHWEST WINDS
EXPECTED OVERNIGHT.  SKIES SHOULD CLEAR OUT NICELY SO EXPECTING MIN
TEMPS TO APPROACH THE DEWPOINTS. SO LOOKING AT LOWS IN THE UPPER 50S
IN THE OUTLYING AREAS...BUT IN THE LOW 60S DOWNTOWN.

JEE

THURSDAY THROUGH SATURDAY...

THE AREA REMAINS ON THE SOUTHWEST SIDE OF THE EASTERN CANADIAN
UPPER LONG WAVE TROUGH THROUGH THE END OF THE WEEK WITH LITTLE
CHANGE IN THE WEATHER PATTERN. AS IS TYPICALLY THE CASE WITH SUCH
AN ESTABLISHED LONG WAVE...MINOR PERTURBATIONS WILL TRAVERSE
DOWN THE BACK SIDE OF THE TROUGH OVER THE WESTERN GREAT
LAKES. EACH OF THESE LOOK TO BRING SUBTLE ENHANCEMENT TO LOW-
LEVEL CONVERGENCE AND KEEP COOL AIR ALOFT FOR ELONGATED CAPE
PROFILES NEAR PEAK HEATING. ALL IN ALL THESE CONTINUE TO PRESENT
MAINLY AFTERNOON AND EARLY EVENING SCATTERED SHOWER/STORM CHANCES.
THERE CONTINUES FAIR MODEL AGREEMENT ON BRINGING AN UPPER/MID
LEVEL SPEED MAX AND AN ASSOCIATED WAVE SOUTHWARD FOR BETTER
COVERAGE OF AFTERNOON SHOWERS/STORMS. BOTH THE SREF AND GEFS
SUPPORT HIGHER POPS OVER A GOOD AMOUNT OF THE AREA AND WHILE THE
MAGNITUDES OF BOTH MAY BE EXTREME /70 PERCENT PLUS/...THE IDEA OF
SCATTERED COVERAGE MORE SO THAN TODAY AND THURSDAY SEEMS LIKELY.
THE ASSOCIATED SURFACE FRONT HANGS UP OVER THE EASTERN FORECAST
AREA. THE LAKE BREEZE WILL CONTINUE TO ALSO BE A FOCUS FOR SHOWERS
AND STORMS...SO DO HAVE A LITTLE HIGHER POPS IN THE NORTHEAST
FORECAST AREA. VERY SLIGHT TEMPERATURE MODERATION IS EXPECTED
THROUGH THIS TIME.

EARLY NEXT WEEK...
HIGH PRESSURE LOOKS TO PREVAIL SATURDAY NIGHT THROUGH THE LATTER
HALF OF THE WEEKEND. THE UPPER LEVEL PATTERN LOOKS TO FLATTEN
SOMEWHAT WITH A QUICK MOVING SYSTEM NORTH OF THE GREAT LAKES
ADVERTISED EARLY NEXT WEEK BY GUIDANCE. THIS LOOKS TO STEER A COOL
FRONT INTO THE REGION WITH LARGE DISCREPANCY ON TIMING AND JUST
HOW FAR SOUTH THIS REACHES. HAVE NOT MADE ANY CHANGES TO A WELL-
VERIFYING BLEND OF GUIDANCE BESIDES INCHING UP TEMPS A COUPLE
DEGREES ON MONDAY AHEAD OF THIS COOL FRONTAL FEATURE.

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 12Z...

* LAKE BREEZE EXPECTED WITH WINDS SHIFTING TO NE ARND 10 KT.

* SCT SHRA THIS AFTN AND EVENING. A FEW TSRA PSBL.

JEE

//DISCUSSION...UPDATED 12Z...

A WEAK COLD FRONT IS PUSHING SOUTH DOWN THE LAKE THIS MORNING AND
IT WILL STALL OUT JUST SOUTH OF THE TERMINALS. WINDS WILL BECOME
NORTHWEST AT 9 KT BEHIND THE FRONT. A LAKE BREEZE IS EXPECTED
TODAY AND IT WILL IMPACT ORD...MDW...AND GYY. NOT SURE IF THE
BREEZE WILL MAKE IT TO DPA SO KEPT A NW WIND AT DPA. WINDS WILL
SHIFT TO NE ARND 10 KT BEHIND THE LAKE BREEZE.

LIKE YESTERDAY...THE LAKE BREEZE WILL BE THE FOCUS FOR SCATTERED
SHOWERS AND A FEW ISOLATED THUNDERSTORMS. NOT EXPECTING AS MANY
THUNDERSTORMS AS YESTERDAY...BUT ANY THUNDERSTORMS THAT DO FORM
WILL HAVE STRONG DOWNDRAFTS AND PRODUCE GUSTY WINDS UP TO 35 KT.

WINDS BACK TO WEST IN THE EVENING AND REMAIN WEST THROUGH THE REST
OF THE PERIOD.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 12Z...

* HIGH CONFIDENCE IN LAKE BREEZE...MEDIUM-HIGH CONFIDENCE IN
  TIMING.

* MEDIUM-HIGH CONFIDENCE IN SHRA DEVELOPMENT AND COVERAGE...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 00Z FRIDAY-12Z WEDNESDAY...UPDATED 12Z...

THURSDAY NIGHT...SCHC TSRA EARLY IN THE EVENING...SCHC SHRA LATE
IN THE EVENING.

FRIDAY...CHC SHRA WITH A CHC OF TSRA IN THE AFTN.

SATURDAY...SCHC SHRA IN THE MORNING...CHC OF TSRA IN THE AFTN.

SUNDAY...VFR.

MONDAY...CHC TSRA OVERNIGHT.

TUESDAY...CHC TSRA.

JEE

&&

.MARINE...
255 AM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE WITH A WEAK COLD
FRONT/UPPER LEVEL WAVE MOVING DOWN THE LAKE EARLY THIS MORNING.
WINDS BECOME NORTH AROUND 10 KT BEHIND THE FRONT. HIGH PRESSURE
OVER THE PLAINS ATTEMPTS TO SPREAD EAST TODAY LEADING TO A
CONTINUED VERY WEAK PRESSURE GRADIENT. ONSHORE FLOW IS EXPECTED
ACROSS NEARSHORE AREAS LEADING TO VARIABLE WINDS 10 KT OR LESS AT
TIMES OVER THE OPEN WATERS. WINDS BECOME MORE UNIFORM THIS EVENING
WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY MORNING. A
COUPLE MORE WEAK COOL FRONTS ARE EXPECTED BY WEEKS END...AT THIS
TIME THURSDAY NIGHT AND AGAIN FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS AND SOME STORMS MAINLY DRIVEN BY THE HEATING OF
THE DAY OVER LAND. SOME OF THESE COULD BE ABLE TO MOVE INTO
NEARSHORE AREAS ON THE WESTERN SIDE OF THE LAKE AS SEEN OVER WI/IL
SHORES LAST EVENING...AND PROFILES OVER LAND DO SUPPORT SOME QUICK
RACING OUTFLOWS/GUST FRONTS FROM SHOWERS THE NEXT FEW DAYS...SO
SOMETHING FOR NEARSHORE MARINERS TO KEEP SOME TABS ON DESPITE THE
MAINLY QUIET WIND/WAVE REGIME.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
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000
FXUS63 KILX 301100
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
600 AM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 317 AM CDT Wed Jul 30 2014
Forecast and overall atmospheric pattern slow to change right now
as an upper low remains parked over the southern tip of Hudson
Bay...with the trof dominating the eastern half of the CONUS. 500
mb ridge over the west, and sfc high pressure building into the
Midwest with northwesterly flow aloft. Forecast driven by slowly
warming temperatures, still below normal for late July, light
winds, and afternoon showers. Next chance for a slightly more
substantial chance for thunderstorms arrives on Friday, with a
wave diving into the upper trof and helping to enhance the
dynamics. Overall, very little in the forecast warranting more
than a chance/scattered mention, and not many changes expected
until the pattern breaks later in the weekend.

SHORT TERM...Today and tomorrow...
Partly cloudy afternoon skies with slight chance for some
afternoon showers and iso thunder... with the better chances to
the northeast. High temperatures upper 70s/low 80s...and overnight
lows dropping to upper 50s/near 60 with mostly clear skies. Upper
low anchored over southeastern Canada keeps the weather in a
pretty stagnant pattern and below normal temps in the Midwest.

LONG TERM...Friday through Tuesday...
Best chances for showers and thunderstorms moving in for Friday...
as a wave rotates through the trof and enhances chances for
scattered showers and thunderstorms. Models pretty consistent with
this feature...though coverage is not expected to be widespread
just yet. High pressure dominating into the weekend as the sfc
ridge axis moves into the region. Winds remain light and variable
and dry forecast as the upper trof finally starts to progress
across into the NE. Chances for more significant weather starting
to return Tues/Wed as a more active and progressive flow sets up
across the country.

HJS

&&

.AVIATION...
ISSUED 600 AM CDT Wed Jul 30 2014

VFR conditions expected at all central Illinois TAF sites for the
next 24hrs. Mostly clear skies will continue until late
morning then scattered cloud cover at 4-5 kft MSL will develop
with daytime heating. Isolated light afternoon showers are
possible...mainly KMTO-KGBG northward...however any MVFR
cigs/vsbys unlikely. After 00Z...any shower activity/cloud cover
diminishing. Winds increasing to WNW7-10 kts by 15Z...becoming
light and variable by 00Z.

Onton

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$







000
FXUS63 KILX 301100
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
600 AM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 317 AM CDT Wed Jul 30 2014
Forecast and overall atmospheric pattern slow to change right now
as an upper low remains parked over the southern tip of Hudson
Bay...with the trof dominating the eastern half of the CONUS. 500
mb ridge over the west, and sfc high pressure building into the
Midwest with northwesterly flow aloft. Forecast driven by slowly
warming temperatures, still below normal for late July, light
winds, and afternoon showers. Next chance for a slightly more
substantial chance for thunderstorms arrives on Friday, with a
wave diving into the upper trof and helping to enhance the
dynamics. Overall, very little in the forecast warranting more
than a chance/scattered mention, and not many changes expected
until the pattern breaks later in the weekend.

SHORT TERM...Today and tomorrow...
Partly cloudy afternoon skies with slight chance for some
afternoon showers and iso thunder... with the better chances to
the northeast. High temperatures upper 70s/low 80s...and overnight
lows dropping to upper 50s/near 60 with mostly clear skies. Upper
low anchored over southeastern Canada keeps the weather in a
pretty stagnant pattern and below normal temps in the Midwest.

LONG TERM...Friday through Tuesday...
Best chances for showers and thunderstorms moving in for Friday...
as a wave rotates through the trof and enhances chances for
scattered showers and thunderstorms. Models pretty consistent with
this feature...though coverage is not expected to be widespread
just yet. High pressure dominating into the weekend as the sfc
ridge axis moves into the region. Winds remain light and variable
and dry forecast as the upper trof finally starts to progress
across into the NE. Chances for more significant weather starting
to return Tues/Wed as a more active and progressive flow sets up
across the country.

HJS

&&

.AVIATION...
ISSUED 600 AM CDT Wed Jul 30 2014

VFR conditions expected at all central Illinois TAF sites for the
next 24hrs. Mostly clear skies will continue until late
morning then scattered cloud cover at 4-5 kft MSL will develop
with daytime heating. Isolated light afternoon showers are
possible...mainly KMTO-KGBG northward...however any MVFR
cigs/vsbys unlikely. After 00Z...any shower activity/cloud cover
diminishing. Winds increasing to WNW7-10 kts by 15Z...becoming
light and variable by 00Z.

Onton

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 300855
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
355 AM CDT WED JUL 30 2014

.DISCUSSION...
315 AM CDT

SYNOPSIS...TODAY WILL BE VERY SIMILAR TO YESTERDAY WITH A LAKE
BREEZE PUSHING INLAND.  SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL FORM ALONG THE BOUNDARY. THERE ARE CHANCES FOR AFTERNOON
THUNDERSTORMS THROUGH SATURDAY WITH THE BETTER CHANCES FRIDAY AND
SATURDAY.  ADDITIONAL THUNDERSTORMS ARE POSSIBLE EARLY NEXT WEEK.
TEMPERATURES SLOWLY RISE THROUGH EARLY NEXT WEEK WITH MID 80 HIGH
TEMPS POSSIBLE MONDAY.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS STILL PARKED OVER JAMES BAY. A SHORT WAVE
TROUGH/COLD FRONT ASSOCIATED WITH THE LOW IS OVER CENTRAL WI AND IT
WILL SLIDE DOWN THE LAKE THROUGH THIS MORNING. THE FRONT LOSES STEAM
THIS AFTERNOON AND STALLS OVER NORTHERN IL AND IN.

A LAKE BREEZE IS ALSO EXPECTED TODAY SO THERE SHOULD BE ADEQUATE
FORCING FOR SHOWERS AND A FEW STORMS BETWEEN THE LAKE BREEZE AND
STALLED OUT COLD FRONT.  CAPE WILL ONCE AGAIN BE LIMITED TO BELOW
500 J/KG SO NOT EXPECTING A TON OF THUNDERSTORM ACTIVITY. UPPER
LEVEL TEMPS AND SURFACE TEMPS WILL BE A BIT COOLER TODAY SO THINKING
THAT WILL ALSO LIMIT INSTABILITY.  ANY STORMS THAT DO FORM WILL NOT
BE SEVERE...BUT MAY BE DOWNDRAFT DRIVEN PRODUCING GUSTY WINDS
LIKE YESTERDAY. HIGH TEMPS WILL BE IN THE UPPER 70S...EXCEPT ALONG
THE LAKE SHORE WHERE THE LAKE BREEZE WILL KEEP HIGH TEMPS IN THE
MID 70S.

SHOWERS AND STORMS DISSIPATE THIS EVENING WITH LIGHT SOUTHWEST WINDS
EXPECTED OVERNIGHT.  SKIES SHOULD CLEAR OUT NICELY SO EXPECTING MIN
TEMPS TO APPROACH THE DEWPOINTS. SO LOOKING AT LOWS IN THE UPPER 50S
IN THE OUTLYING AREAS...BUT IN THE LOW 60S DOWNTOWN.

JEE

THURSDAY THROUGH SATURDAY...

THE AREA REMAINS ON THE SOUTHWEST SIDE OF THE EASTERN CANADIAN
UPPER LONG WAVE TROUGH THROUGH THE END OF THE WEEK WITH LITTLE
CHANGE IN THE WEATHER PATTERN. AS IS TYPICALLY THE CASE WITH SUCH
AN ESTABLISHED LONG WAVE...MINOR PERTURBATIONS WILL TRAVERSE
DOWN THE BACK SIDE OF THE TROUGH OVER THE WESTERN GREAT
LAKES. EACH OF THESE LOOK TO BRING SUBTLE ENHANCEMENT TO LOW-
LEVEL CONVERGENCE AND KEEP COOL AIR ALOFT FOR ELONGATED CAPE
PROFILES NEAR PEAK HEATING. ALL IN ALL THESE CONTINUE TO PRESENT
MAINLY AFTERNOON AND EARLY EVENING SCATTERED SHOWER/STORM CHANCES.
THERE CONTINUES FAIR MODEL AGREEMENT ON BRINGING AN UPPER/MID
LEVEL SPEED MAX AND AN ASSOCIATED WAVE SOUTHWARD FOR BETTER
COVERAGE OF AFTERNOON SHOWERS/STORMS. BOTH THE SREF AND GEFS
SUPPORT HIGHER POPS OVER A GOOD AMOUNT OF THE AREA AND WHILE THE
MAGNITUDES OF BOTH MAY BE EXTREME /70 PERCENT PLUS/...THE IDEA OF
SCATTERED COVERAGE MORE SO THAN TODAY AND THURSDAY SEEMS LIKELY.
THE ASSOCIATED SURFACE FRONT HANGS UP OVER THE EASTERN FORECAST
AREA. THE LAKE BREEZE WILL CONTINUE TO ALSO BE A FOCUS FOR SHOWERS
AND STORMS...SO DO HAVE A LITTLE HIGHER POPS IN THE NORTHEAST
FORECAST AREA. VERY SLIGHT TEMPERATURE MODERATION IS EXPECTED
THROUGH THIS TIME.

EARLY NEXT WEEK...
HIGH PRESSURE LOOKS TO PREVAIL SATURDAY NIGHT THROUGH THE LATTER
HALF OF THE WEEKEND. THE UPPER LEVEL PATTERN LOOKS TO FLATTEN
SOMEWHAT WITH A QUICK MOVING SYSTEM NORTH OF THE GREAT LAKES
ADVERTISED EARLY NEXT WEEK BY GUIDANCE. THIS LOOKS TO STEER A COOL
FRONT INTO THE REGION WITH LARGE DISCREPANCY ON TIMING AND JUST
HOW FAR SOUTH THIS REACHES. HAVE NOT MADE ANY CHANGES TO A WELL-
VERIFYING BLEND OF GUIDANCE BESIDES INCHING UP TEMPS A COUPLE
DEGREES ON MONDAY AHEAD OF THIS COOL FRONTAL FEATURE.

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* LAKE BREEZE EXPECTED WITH NE WINDS AT 10 KT BEHIND IT.

* SCT SHRA THIS AFTN AND EVENING. A FEW TSRA PSBL.

JEE

//DISCUSSION...UPDATED 06Z...

SHOWERS HAVE PUSHED SOUTH OF THE TERMINALS BUT TODAY IS LOOKING
VERY SIMILAR TO YESTERDAY. A LAKE BREEZE IS EXPECTED ALONG WITH A
WEAKER UPPER LEVEL WAVE. THE LAKE BREEZE WILL PROVIDE ENOUGH
FORCING FOR SCT SHRA THIS AFTN AND EVENING...BUT THINKING WE WILL
SEE LESS ACTIVITY THAN YESTERDAY. A FEW THUNDERSTORMS ARE ALSO
EXPECTED AS WELL BUT THEY SHOULD BE ISOLATED ENOUGH TO LEAVE OUT
OF THE TAF FOR NOW.

WINDS BECOME NE ARND 10 KT BEHIND THE LAKE BREEZE AT MDW AND
ORD....AND NNE AT GYY. HAVE HIGH CONFIDENCE THAT THE LAKE BREEZE
WILL MAKE IT THROUGH MDW AND GYY AND MEDIUM-HIGH CONFIDENCE ABOUT
ORD. WINDS SLOWLY RETURN TO THE SW IN THE EVENING WITH CONTINUED
VFR CONDITIONS.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* HIGH CONFIDENCE IN LAKE BREEZE...MEDIUM CONFIDENCE IN
  TIMING...MEDIUM CONFIDENCE IN HOW FAR INLAND IT TRAVELS.

* MEDIUM-HIGH CONFIDENCE IN SHRA DEVELOPMENT AND COVERAGE...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY...SLIGHT CHANCE TSRA IN AFTN

FRIDAY...SLIGHT CHANCE TSRA IN AFTN

SATURDAY...CHANCE TSRA

SUNDAY...VFR

MONDAY...SLIGHT CHANCE TSRA

DANIELSON/RODRIGUEZ

&&

.MARINE...
255 AM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE WITH A WEAK COLD
FRONT/UPPER LEVEL WAVE MOVING DOWN THE LAKE EARLY THIS MORNING.
WINDS BECOME NORTH AROUND 10 KT BEHIND THE FRONT. HIGH PRESSURE
OVER THE PLAINS ATTEMPTS TO SPREAD EAST TODAY LEADING TO A
CONTINUED VERY WEAK PRESSURE GRADIENT. ONSHORE FLOW IS EXPECTED
ACROSS NEARSHORE AREAS LEADING TO VARIABLE WINDS 10 KT OR LESS AT
TIMES OVER THE OPEN WATERS. WINDS BECOME MORE UNIFORM THIS EVENING
WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY MORNING. A
COUPLE MORE WEAK COOL FRONTS ARE EXPECTED BY WEEKS END...AT THIS
TIME THURSDAY NIGHT AND AGAIN FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS AND SOME STORMS MAINLY DRIVEN BY THE HEATING OF
THE DAY OVER LAND. SOME OF THESE COULD BE ABLE TO MOVE INTO
NEARSHORE AREAS ON THE WESTERN SIDE OF THE LAKE AS SEEN OVER WI/IL
SHORES LAST EVENING...AND PROFILES OVER LAND DO SUPPORT SOME QUICK
RACING OUTFLOWS/GUST FRONTS FROM SHOWERS THE NEXT FEW DAYS...SO
SOMETHING FOR NEARSHORE MARINERS TO KEEP SOME TABS ON DESPITE THE
MAINLY QUIET WIND/WAVE REGIME.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 300855
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
355 AM CDT WED JUL 30 2014

.DISCUSSION...
315 AM CDT

SYNOPSIS...TODAY WILL BE VERY SIMILAR TO YESTERDAY WITH A LAKE
BREEZE PUSHING INLAND.  SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL FORM ALONG THE BOUNDARY. THERE ARE CHANCES FOR AFTERNOON
THUNDERSTORMS THROUGH SATURDAY WITH THE BETTER CHANCES FRIDAY AND
SATURDAY.  ADDITIONAL THUNDERSTORMS ARE POSSIBLE EARLY NEXT WEEK.
TEMPERATURES SLOWLY RISE THROUGH EARLY NEXT WEEK WITH MID 80 HIGH
TEMPS POSSIBLE MONDAY.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS STILL PARKED OVER JAMES BAY. A SHORT WAVE
TROUGH/COLD FRONT ASSOCIATED WITH THE LOW IS OVER CENTRAL WI AND IT
WILL SLIDE DOWN THE LAKE THROUGH THIS MORNING. THE FRONT LOSES STEAM
THIS AFTERNOON AND STALLS OVER NORTHERN IL AND IN.

A LAKE BREEZE IS ALSO EXPECTED TODAY SO THERE SHOULD BE ADEQUATE
FORCING FOR SHOWERS AND A FEW STORMS BETWEEN THE LAKE BREEZE AND
STALLED OUT COLD FRONT.  CAPE WILL ONCE AGAIN BE LIMITED TO BELOW
500 J/KG SO NOT EXPECTING A TON OF THUNDERSTORM ACTIVITY. UPPER
LEVEL TEMPS AND SURFACE TEMPS WILL BE A BIT COOLER TODAY SO THINKING
THAT WILL ALSO LIMIT INSTABILITY.  ANY STORMS THAT DO FORM WILL NOT
BE SEVERE...BUT MAY BE DOWNDRAFT DRIVEN PRODUCING GUSTY WINDS
LIKE YESTERDAY. HIGH TEMPS WILL BE IN THE UPPER 70S...EXCEPT ALONG
THE LAKE SHORE WHERE THE LAKE BREEZE WILL KEEP HIGH TEMPS IN THE
MID 70S.

SHOWERS AND STORMS DISSIPATE THIS EVENING WITH LIGHT SOUTHWEST WINDS
EXPECTED OVERNIGHT.  SKIES SHOULD CLEAR OUT NICELY SO EXPECTING MIN
TEMPS TO APPROACH THE DEWPOINTS. SO LOOKING AT LOWS IN THE UPPER 50S
IN THE OUTLYING AREAS...BUT IN THE LOW 60S DOWNTOWN.

JEE

THURSDAY THROUGH SATURDAY...

THE AREA REMAINS ON THE SOUTHWEST SIDE OF THE EASTERN CANADIAN
UPPER LONG WAVE TROUGH THROUGH THE END OF THE WEEK WITH LITTLE
CHANGE IN THE WEATHER PATTERN. AS IS TYPICALLY THE CASE WITH SUCH
AN ESTABLISHED LONG WAVE...MINOR PERTURBATIONS WILL TRAVERSE
DOWN THE BACK SIDE OF THE TROUGH OVER THE WESTERN GREAT
LAKES. EACH OF THESE LOOK TO BRING SUBTLE ENHANCEMENT TO LOW-
LEVEL CONVERGENCE AND KEEP COOL AIR ALOFT FOR ELONGATED CAPE
PROFILES NEAR PEAK HEATING. ALL IN ALL THESE CONTINUE TO PRESENT
MAINLY AFTERNOON AND EARLY EVENING SCATTERED SHOWER/STORM CHANCES.
THERE CONTINUES FAIR MODEL AGREEMENT ON BRINGING AN UPPER/MID
LEVEL SPEED MAX AND AN ASSOCIATED WAVE SOUTHWARD FOR BETTER
COVERAGE OF AFTERNOON SHOWERS/STORMS. BOTH THE SREF AND GEFS
SUPPORT HIGHER POPS OVER A GOOD AMOUNT OF THE AREA AND WHILE THE
MAGNITUDES OF BOTH MAY BE EXTREME /70 PERCENT PLUS/...THE IDEA OF
SCATTERED COVERAGE MORE SO THAN TODAY AND THURSDAY SEEMS LIKELY.
THE ASSOCIATED SURFACE FRONT HANGS UP OVER THE EASTERN FORECAST
AREA. THE LAKE BREEZE WILL CONTINUE TO ALSO BE A FOCUS FOR SHOWERS
AND STORMS...SO DO HAVE A LITTLE HIGHER POPS IN THE NORTHEAST
FORECAST AREA. VERY SLIGHT TEMPERATURE MODERATION IS EXPECTED
THROUGH THIS TIME.

EARLY NEXT WEEK...
HIGH PRESSURE LOOKS TO PREVAIL SATURDAY NIGHT THROUGH THE LATTER
HALF OF THE WEEKEND. THE UPPER LEVEL PATTERN LOOKS TO FLATTEN
SOMEWHAT WITH A QUICK MOVING SYSTEM NORTH OF THE GREAT LAKES
ADVERTISED EARLY NEXT WEEK BY GUIDANCE. THIS LOOKS TO STEER A COOL
FRONT INTO THE REGION WITH LARGE DISCREPANCY ON TIMING AND JUST
HOW FAR SOUTH THIS REACHES. HAVE NOT MADE ANY CHANGES TO A WELL-
VERIFYING BLEND OF GUIDANCE BESIDES INCHING UP TEMPS A COUPLE
DEGREES ON MONDAY AHEAD OF THIS COOL FRONTAL FEATURE.

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* LAKE BREEZE EXPECTED WITH NE WINDS AT 10 KT BEHIND IT.

* SCT SHRA THIS AFTN AND EVENING. A FEW TSRA PSBL.

JEE

//DISCUSSION...UPDATED 06Z...

SHOWERS HAVE PUSHED SOUTH OF THE TERMINALS BUT TODAY IS LOOKING
VERY SIMILAR TO YESTERDAY. A LAKE BREEZE IS EXPECTED ALONG WITH A
WEAKER UPPER LEVEL WAVE. THE LAKE BREEZE WILL PROVIDE ENOUGH
FORCING FOR SCT SHRA THIS AFTN AND EVENING...BUT THINKING WE WILL
SEE LESS ACTIVITY THAN YESTERDAY. A FEW THUNDERSTORMS ARE ALSO
EXPECTED AS WELL BUT THEY SHOULD BE ISOLATED ENOUGH TO LEAVE OUT
OF THE TAF FOR NOW.

WINDS BECOME NE ARND 10 KT BEHIND THE LAKE BREEZE AT MDW AND
ORD....AND NNE AT GYY. HAVE HIGH CONFIDENCE THAT THE LAKE BREEZE
WILL MAKE IT THROUGH MDW AND GYY AND MEDIUM-HIGH CONFIDENCE ABOUT
ORD. WINDS SLOWLY RETURN TO THE SW IN THE EVENING WITH CONTINUED
VFR CONDITIONS.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* HIGH CONFIDENCE IN LAKE BREEZE...MEDIUM CONFIDENCE IN
  TIMING...MEDIUM CONFIDENCE IN HOW FAR INLAND IT TRAVELS.

* MEDIUM-HIGH CONFIDENCE IN SHRA DEVELOPMENT AND COVERAGE...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY...SLIGHT CHANCE TSRA IN AFTN

FRIDAY...SLIGHT CHANCE TSRA IN AFTN

SATURDAY...CHANCE TSRA

SUNDAY...VFR

MONDAY...SLIGHT CHANCE TSRA

DANIELSON/RODRIGUEZ

&&

.MARINE...
255 AM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE WITH A WEAK COLD
FRONT/UPPER LEVEL WAVE MOVING DOWN THE LAKE EARLY THIS MORNING.
WINDS BECOME NORTH AROUND 10 KT BEHIND THE FRONT. HIGH PRESSURE
OVER THE PLAINS ATTEMPTS TO SPREAD EAST TODAY LEADING TO A
CONTINUED VERY WEAK PRESSURE GRADIENT. ONSHORE FLOW IS EXPECTED
ACROSS NEARSHORE AREAS LEADING TO VARIABLE WINDS 10 KT OR LESS AT
TIMES OVER THE OPEN WATERS. WINDS BECOME MORE UNIFORM THIS EVENING
WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY MORNING. A
COUPLE MORE WEAK COOL FRONTS ARE EXPECTED BY WEEKS END...AT THIS
TIME THURSDAY NIGHT AND AGAIN FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS AND SOME STORMS MAINLY DRIVEN BY THE HEATING OF
THE DAY OVER LAND. SOME OF THESE COULD BE ABLE TO MOVE INTO
NEARSHORE AREAS ON THE WESTERN SIDE OF THE LAKE AS SEEN OVER WI/IL
SHORES LAST EVENING...AND PROFILES OVER LAND DO SUPPORT SOME QUICK
RACING OUTFLOWS/GUST FRONTS FROM SHOWERS THE NEXT FEW DAYS...SO
SOMETHING FOR NEARSHORE MARINERS TO KEEP SOME TABS ON DESPITE THE
MAINLY QUIET WIND/WAVE REGIME.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KILX 300831
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
331 AM CDT Wed Jul 30 2014

.DISCUSSION...
ISSUED 317 AM CDT Wed Jul 30 2014
Forecast and overall atmospheric pattern slow to change right now
as an upper low remains parked over the southern tip of Hudson
Bay...with the trof dominating the eastern half of the CONUS. 500
mb ridge over the west, and sfc high pressure building into the
Midwest with northwesterly flow aloft. Forecast driven by slowly
warming temperatures, still below normal for late July, light
winds, and afternoon showers. Next chance for a slightly more
substantial chance for thunderstorms arrives on Friday, with a
wave diving into the upper trof and helping to enhance the
dynamics. Overall, very little in the forecast warranting more
than a chance/scattered mention, and not many changes expected
until the pattern breaks later in the weekend.

SHORT TERM...Today and tomorrow...
Partly cloudy afternoon skies with slight chance for some
afternoon showers and iso thunder... with the better chances to
the northeast. High temperatures upper 70s/low 80s...and overnight
lows dropping to upper 50s/near 60 with mostly clear skies. Upper
low anchored over southeastern Canada keeps the weather in a
pretty stagnant pattern and below normal temps in the Midwest.

LONG TERM...Friday through Tuesday...
Best chances for showers and thunderstorms moving in for Friday...
as a wave rotates through the trof and enhances chances for
scattered showers and thunderstorms. Models pretty consistent with
this feature...though coverage is not expected to be widespread
just yet. High pressure dominating into the weekend as the sfc
ridge axis moves into the region. Winds remain light and variable
and dry forecast as the upper trof finally starts to progress
across into the NE. Chances for more significant weather starting
to return Tues/Wed as a more active and progressive flow sets up
across the country.

HJS
&&

.AVIATION...
ISSUED 1155 PM CDT Tue Jul 29 2014

Clear skies and light winds will continue overnight. VFR conditions
will continue at all TAF sites next 24hrs. A line of scattered showers
continues to move southeast through northeast IL tonight. Though
it looks like they could reach toward Champaign, they should miss
the TAF site overnight. Will not have any pcpn mentioned at CMI at
this time. Winds tomorrow will be westerly at around 10kts with
scattered CU around 5kft and then dissipate again tomorrow evening
with lighter winds.

Auten
&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 300821
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
321 AM CDT WED JUL 30 2014

.DISCUSSION...
315 AM CDT

SYNOPSIS...TODAY WILL BE VERY SIMILAR TO YESTERDAY WITH A LAKE
BREEZE PUSHING INLAND.  SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL FORM ALONG THE BOUNDARY. THERE ARE CHANCES FOR AFTERNOON
THUNDERSTORMS THROUGH SATURDAY WITH THE BETTER CHANCES FRIDAY AND
SATURDAY.  ADDITIONAL THUNDERSTORMS ARE POSSIBLE EARLY NEXT WEEK.
TEMPERATURES SLOWLY RISE THROUGH EARLY NEXT WEEK WITH MID 80 HIGH
TEMPS POSSIBLE MONDAY.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS STILL PARKED OVER JAMES BAY. A SHORT WAVE
TROUGH/COLD FRONT ASSOCIATED WITH THE LOW IS OVER CENTRAL WI AND IT
WILL SLIDE DOWN THE LAKE THROUGH THIS MORNING. THE FRONT LOSES STEAM
THIS AFTERNOON AND STALLS OVER NORTHERN IL AND IN.

A LAKE BREEZE IS ALSO EXPECTED TODAY SO THERE SHOULD BE ADEQUATE
FORCING FOR SHOWERS AND A FEW STORMS BETWEEN THE LAKE BREEZE AND
STALLED OUT COLD FRONT.  CAPE WILL ONCE AGAIN BE LIMITED TO BELOW
500 J/KG SO NOT EXPECTING A TON OF THUNDERSTORM ACTIVITY. UPPER
LEVEL TEMPS AND SURFACE TEMPS WILL BE A BIT COOLER TODAY SO THINKING
THAT WILL ALSO LIMIT INSTABILITY.  ANY STORMS THAT DO FORM WILL NOT
BE SEVERE...BUT MAY BE DOWNDRAFT DRIVEN PRODUCING GUSTY WINDS
LIKE YESTERDAY. HIGH TEMPS WILL BE IN THE UPPER 70S...EXCEPT ALONG
THE LAKE SHORE WHERE THE LAKE BREEZE WILL KEEP HIGH TEMPS IN THE
MID 70S.

SHOWERS AND STORMS DISSIPATE THIS EVENING WITH LIGHT SOUTHWEST WINDS
EXPECTED OVERNIGHT.  SKIES SHOULD CLEAR OUT NICELY SO EXPECTING MIN
TEMPS TO APPROACH THE DEWPOINTS. SO LOOKING AT LOWS IN THE UPPER 50S
IN THE OUTLYING AREAS...BUT IN THE LOW 60S DOWNTOWN.

JEE

THURSDAY THROUGH SATURDAY...

THE AREA REMAINS ON THE SOUTHWEST SIDE OF THE EASTERN CANADIAN
UPPER LONG WAVE TROUGH THROUGH THE END OF THE WEEK WITH LITTLE
CHANGE IN THE WEATHER PATTERN. AS IS TYPICALLY THE CASE WITH SUCH
AN ESTABLISHED LONG WAVE...MINOR PERTURBATIONS WILL TRAVERSE
DOWN THE BACK SIDE OF THE TROUGH OVER THE WESTERN GREAT
LAKES. EACH OF THESE LOOK TO BRING SUBTLE ENHANCEMENT TO LOW-
LEVEL CONVERGENCE AND KEEP COOL AIR ALOFT FOR ELONGATED CAPE
PROFILES NEAR PEAK HEATING. ALL IN ALL THESE CONTINUE TO PRESENT
MAINLY AFTERNOON AND EARLY EVENING SCATTERED SHOWER/STORM CHANCES.
THERE CONTINUES FAIR MODEL AGREEMENT ON BRINGING AN UPPER/MID
LEVEL SPEED MAX AND AN ASSOCIATED WAVE SOUTHWARD FOR BETTER
COVERAGE OF AFTERNOON SHOWERS/STORMS. BOTH THE SREF AND GEFS
SUPPORT HIGHER POPS OVER A GOOD AMOUNT OF THE AREA AND WHILE THE
MAGNITUDES OF BOTH MAY BE EXTREME /70 PERCENT PLUS/...THE IDEA OF
SCATTERED COVERAGE MORE SO THAN TODAY AND THURSDAY SEEMS LIKELY.
THE ASSOCIATED SURFACE FRONT HANGS UP OVER THE EASTERN FORECAST
AREA. THE LAKE BREEZE WILL CONTINUE TO ALSO BE A FOCUS FOR SHOWERS
AND STORMS...SO DO HAVE A LITTLE HIGHER POPS IN THE NORTHEAST
FORECAST AREA. VERY SLIGHT TEMPERATURE MODERATION IS EXPECTED
THROUGH THIS TIME.

EARLY NEXT WEEK...
HIGH PRESSURE LOOKS TO PREVAIL SATURDAY NIGHT THROUGH THE LATTER
HALF OF THE WEEKEND. THE UPPER LEVEL PATTERN LOOKS TO FLATTEN
SOMEWHAT WITH A QUICK MOVING SYSTEM NORTH OF THE GREAT LAKES
ADVERTISED EARLY NEXT WEEK BY GUIDANCE. THIS LOOKS TO STEER A COOL
FRONT INTO THE REGION WITH LARGE DISCREPANCY ON TIMING AND JUST
HOW FAR SOUTH THIS REACHES. HAVE NOT MADE ANY CHANGES TO A WELL-
VERIFYING BLEND OF GUIDANCE BESIDES INCHING UP TEMPS A COUPLE
DEGREES ON MONDAY AHEAD OF THIS COOL FRONTAL FEATURE.

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* LAKE BREEZE EXPECTED WITH NE WINDS AT 10 KT BEHIND IT.

* SCT SHRA THIS AFTN AND EVENING. A FEW TSRA PSBL.

JEE

//DISCUSSION...UPDATED 06Z...

SHOWERS HAVE PUSHED SOUTH OF THE TERMINALS BUT TODAY IS LOOKING
VERY SIMILAR TO YESTERDAY. A LAKE BREEZE IS EXPECTED ALONG WITH A
WEAKER UPPER LEVEL WAVE. THE LAKE BREEZE WILL PROVIDE ENOUGH
FORCING FOR SCT SHRA THIS AFTN AND EVENING...BUT THINKING WE WILL
SEE LESS ACTIVITY THAN YESTERDAY. A FEW THUNDERSTORMS ARE ALSO
EXPECTED AS WELL BUT THEY SHOULD BE ISOLATED ENOUGH TO LEAVE OUT
OF THE TAF FOR NOW.

WINDS BECOME NE ARND 10 KT BEHIND THE LAKE BREEZE AT MDW AND
ORD....AND NNE AT GYY. HAVE HIGH CONFIDENCE THAT THE LAKE BREEZE
WILL MAKE IT THROUGH MDW AND GYY AND MEDIUM-HIGH CONFIDENCE ABOUT
ORD. WINDS SLOWLY RETURN TO THE SW IN THE EVENING WITH CONTINUED
VFR CONDITIONS.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* HIGH CONFIDENCE IN LAKE BREEZE...MEDIUM CONFIDENCE IN
  TIMING...MEDIUM CONFIDENCE IN HOW FAR INLAND IT TRAVELS.

* MEDIUM-HIGH CONFIDENCE IN SHRA DEVELOPMENT AND COVERAGE...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY...SLIGHT CHANCE TSRA IN AFTN

FRIDAY...SLIGHT CHANCE TSRA IN AFTN

SATURDAY...CHANCE TSRA

SUNDAY...VFR

MONDAY...SLIGHT CHANCE TSRA

DANIELSON/RODRIGUEZ

&&

.MARINE...
255 AM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE WITH A WEAK COLD
FRONT/UPPER LEVEL WAVE MOVING DOWN THE LAKE EARLY THIS MORNING.
WINDS BECOME NORTH AROUND 10 KT BEHIND THE FRONT. HIGH PRESSURE
OVER THE PLAINS ATTEMPTS TO SPREAD EAST TODAY LEADING TO A
CONTINUED VERY WEAK PRESSURE GRADIENT. ONSHORE FLOW IS EXPECTED
ACROSS NEARSHORE AREAS LEADING TO VARIABLE WINDS 10 KT OR LESS AT
TIMES OVER THE OPEN WATERS. WINDS BECOME MORE UNIFORM THIS EVENING
WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY MORNING. A
COUPLE MORE WEAK COOL FRONTS ARE EXPECTED BY WEEKS END...AT THIS
TIME THURSDAY NIGHT AND AGAIN FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS AND SOME STORMS MAINLY DRIVEN BY THE HEATING OF
THE DAY OVER LAND. SOME OF THESE COULD BE ABLE TO MOVE INTO
NEARSHORE AREAS ON THE WESTERN SIDE OF THE LAKE AS SEEN OVER WI/IL
SHORES LAST EVENING...AND PROFILES OVER LAND DO SUPPORT SOME QUICK
RACING OUTFLOWS/GUST FRONTS FROM SHOWERS THE NEXT FEW DAYS...SO
SOMETHING FOR NEARSHORE MARINERS TO KEEP SOME TABS ON DESPITE THE
MAINLY QUIET WIND/WAVE REGIME.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 300821
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
321 AM CDT WED JUL 30 2014

.DISCUSSION...
315 AM CDT

SYNOPSIS...TODAY WILL BE VERY SIMILAR TO YESTERDAY WITH A LAKE
BREEZE PUSHING INLAND.  SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL FORM ALONG THE BOUNDARY. THERE ARE CHANCES FOR AFTERNOON
THUNDERSTORMS THROUGH SATURDAY WITH THE BETTER CHANCES FRIDAY AND
SATURDAY.  ADDITIONAL THUNDERSTORMS ARE POSSIBLE EARLY NEXT WEEK.
TEMPERATURES SLOWLY RISE THROUGH EARLY NEXT WEEK WITH MID 80 HIGH
TEMPS POSSIBLE MONDAY.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS STILL PARKED OVER JAMES BAY. A SHORT WAVE
TROUGH/COLD FRONT ASSOCIATED WITH THE LOW IS OVER CENTRAL WI AND IT
WILL SLIDE DOWN THE LAKE THROUGH THIS MORNING. THE FRONT LOSES STEAM
THIS AFTERNOON AND STALLS OVER NORTHERN IL AND IN.

A LAKE BREEZE IS ALSO EXPECTED TODAY SO THERE SHOULD BE ADEQUATE
FORCING FOR SHOWERS AND A FEW STORMS BETWEEN THE LAKE BREEZE AND
STALLED OUT COLD FRONT.  CAPE WILL ONCE AGAIN BE LIMITED TO BELOW
500 J/KG SO NOT EXPECTING A TON OF THUNDERSTORM ACTIVITY. UPPER
LEVEL TEMPS AND SURFACE TEMPS WILL BE A BIT COOLER TODAY SO THINKING
THAT WILL ALSO LIMIT INSTABILITY.  ANY STORMS THAT DO FORM WILL NOT
BE SEVERE...BUT MAY BE DOWNDRAFT DRIVEN PRODUCING GUSTY WINDS
LIKE YESTERDAY. HIGH TEMPS WILL BE IN THE UPPER 70S...EXCEPT ALONG
THE LAKE SHORE WHERE THE LAKE BREEZE WILL KEEP HIGH TEMPS IN THE
MID 70S.

SHOWERS AND STORMS DISSIPATE THIS EVENING WITH LIGHT SOUTHWEST WINDS
EXPECTED OVERNIGHT.  SKIES SHOULD CLEAR OUT NICELY SO EXPECTING MIN
TEMPS TO APPROACH THE DEWPOINTS. SO LOOKING AT LOWS IN THE UPPER 50S
IN THE OUTLYING AREAS...BUT IN THE LOW 60S DOWNTOWN.

JEE

THURSDAY THROUGH SATURDAY...

THE AREA REMAINS ON THE SOUTHWEST SIDE OF THE EASTERN CANADIAN
UPPER LONG WAVE TROUGH THROUGH THE END OF THE WEEK WITH LITTLE
CHANGE IN THE WEATHER PATTERN. AS IS TYPICALLY THE CASE WITH SUCH
AN ESTABLISHED LONG WAVE...MINOR PERTURBATIONS WILL TRAVERSE
DOWN THE BACK SIDE OF THE TROUGH OVER THE WESTERN GREAT
LAKES. EACH OF THESE LOOK TO BRING SUBTLE ENHANCEMENT TO LOW-
LEVEL CONVERGENCE AND KEEP COOL AIR ALOFT FOR ELONGATED CAPE
PROFILES NEAR PEAK HEATING. ALL IN ALL THESE CONTINUE TO PRESENT
MAINLY AFTERNOON AND EARLY EVENING SCATTERED SHOWER/STORM CHANCES.
THERE CONTINUES FAIR MODEL AGREEMENT ON BRINGING AN UPPER/MID
LEVEL SPEED MAX AND AN ASSOCIATED WAVE SOUTHWARD FOR BETTER
COVERAGE OF AFTERNOON SHOWERS/STORMS. BOTH THE SREF AND GEFS
SUPPORT HIGHER POPS OVER A GOOD AMOUNT OF THE AREA AND WHILE THE
MAGNITUDES OF BOTH MAY BE EXTREME /70 PERCENT PLUS/...THE IDEA OF
SCATTERED COVERAGE MORE SO THAN TODAY AND THURSDAY SEEMS LIKELY.
THE ASSOCIATED SURFACE FRONT HANGS UP OVER THE EASTERN FORECAST
AREA. THE LAKE BREEZE WILL CONTINUE TO ALSO BE A FOCUS FOR SHOWERS
AND STORMS...SO DO HAVE A LITTLE HIGHER POPS IN THE NORTHEAST
FORECAST AREA. VERY SLIGHT TEMPERATURE MODERATION IS EXPECTED
THROUGH THIS TIME.

EARLY NEXT WEEK...
HIGH PRESSURE LOOKS TO PREVAIL SATURDAY NIGHT THROUGH THE LATTER
HALF OF THE WEEKEND. THE UPPER LEVEL PATTERN LOOKS TO FLATTEN
SOMEWHAT WITH A QUICK MOVING SYSTEM NORTH OF THE GREAT LAKES
ADVERTISED EARLY NEXT WEEK BY GUIDANCE. THIS LOOKS TO STEER A COOL
FRONT INTO THE REGION WITH LARGE DISCREPANCY ON TIMING AND JUST
HOW FAR SOUTH THIS REACHES. HAVE NOT MADE ANY CHANGES TO A WELL-
VERIFYING BLEND OF GUIDANCE BESIDES INCHING UP TEMPS A COUPLE
DEGREES ON MONDAY AHEAD OF THIS COOL FRONTAL FEATURE.

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* LAKE BREEZE EXPECTED WITH NE WINDS AT 10 KT BEHIND IT.

* SCT SHRA THIS AFTN AND EVENING. A FEW TSRA PSBL.

JEE

//DISCUSSION...UPDATED 06Z...

SHOWERS HAVE PUSHED SOUTH OF THE TERMINALS BUT TODAY IS LOOKING
VERY SIMILAR TO YESTERDAY. A LAKE BREEZE IS EXPECTED ALONG WITH A
WEAKER UPPER LEVEL WAVE. THE LAKE BREEZE WILL PROVIDE ENOUGH
FORCING FOR SCT SHRA THIS AFTN AND EVENING...BUT THINKING WE WILL
SEE LESS ACTIVITY THAN YESTERDAY. A FEW THUNDERSTORMS ARE ALSO
EXPECTED AS WELL BUT THEY SHOULD BE ISOLATED ENOUGH TO LEAVE OUT
OF THE TAF FOR NOW.

WINDS BECOME NE ARND 10 KT BEHIND THE LAKE BREEZE AT MDW AND
ORD....AND NNE AT GYY. HAVE HIGH CONFIDENCE THAT THE LAKE BREEZE
WILL MAKE IT THROUGH MDW AND GYY AND MEDIUM-HIGH CONFIDENCE ABOUT
ORD. WINDS SLOWLY RETURN TO THE SW IN THE EVENING WITH CONTINUED
VFR CONDITIONS.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* HIGH CONFIDENCE IN LAKE BREEZE...MEDIUM CONFIDENCE IN
  TIMING...MEDIUM CONFIDENCE IN HOW FAR INLAND IT TRAVELS.

* MEDIUM-HIGH CONFIDENCE IN SHRA DEVELOPMENT AND COVERAGE...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY...SLIGHT CHANCE TSRA IN AFTN

FRIDAY...SLIGHT CHANCE TSRA IN AFTN

SATURDAY...CHANCE TSRA

SUNDAY...VFR

MONDAY...SLIGHT CHANCE TSRA

DANIELSON/RODRIGUEZ

&&

.MARINE...
255 AM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE WITH A WEAK COLD
FRONT/UPPER LEVEL WAVE MOVING DOWN THE LAKE EARLY THIS MORNING.
WINDS BECOME NORTH AROUND 10 KT BEHIND THE FRONT. HIGH PRESSURE
OVER THE PLAINS ATTEMPTS TO SPREAD EAST TODAY LEADING TO A
CONTINUED VERY WEAK PRESSURE GRADIENT. ONSHORE FLOW IS EXPECTED
ACROSS NEARSHORE AREAS LEADING TO VARIABLE WINDS 10 KT OR LESS AT
TIMES OVER THE OPEN WATERS. WINDS BECOME MORE UNIFORM THIS EVENING
WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY MORNING. A
COUPLE MORE WEAK COOL FRONTS ARE EXPECTED BY WEEKS END...AT THIS
TIME THURSDAY NIGHT AND AGAIN FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS AND SOME STORMS MAINLY DRIVEN BY THE HEATING OF
THE DAY OVER LAND. SOME OF THESE COULD BE ABLE TO MOVE INTO
NEARSHORE AREAS ON THE WESTERN SIDE OF THE LAKE AS SEEN OVER WI/IL
SHORES LAST EVENING...AND PROFILES OVER LAND DO SUPPORT SOME QUICK
RACING OUTFLOWS/GUST FRONTS FROM SHOWERS THE NEXT FEW DAYS...SO
SOMETHING FOR NEARSHORE MARINERS TO KEEP SOME TABS ON DESPITE THE
MAINLY QUIET WIND/WAVE REGIME.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO








000
FXUS63 KLOT 300756
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
256 AM CDT WED JUL 30 2014

.DISCUSSION...
218 PM CDT

FORECAST ISSUES CONTINUE TO FOCUS ON DAILY DIURNAL ISOLATED TO
SCATTERED SHOWER/THUNDERSTORM CHANCES...WITH VERY GRADUAL WARM UP IN
TEMPERATURES THROUGH THE FORECAST PERIOD AS LONG WAVE UPPER TROUGH
OVER EASTERN NORTH AMERICA EFFECTIVELY RETROGRADES THROUGH THE END
OF THE WEEK BEFORE FINALLY WEAKENING AND PROGRESSING OFF TO THE
NORTHEAST BY LATE WEEKEND AND EARLY NEXT WEEK.

WESTERN GREAT LAKES REGION REMAINS IN WESTERN PERIPHERY OF THIS
AFOREMENTIONED TROUGH...WITHIN REGION OF BROAD CYCLONIC CIRCULATION.
SERIES OF RELATIVELY MINOR SHORT WAVES WILL CONTINUE TO RIPPLE
SOUTH-SOUTHEAST THROUGH THE FLOW ACROSS THE AREA THROUGH THE
REMAINDER OF THE WEEK. GOES WATER VAPOR IMAGERY INDICATES A COUPLE
OF WEAK RIPPLES PASSED ACROSS THE REGION THIS MORNING...WITH A
SOMEWHAT MORE ROBUST SHORT WAVE NOTED UPSTREAM PROPAGATING SOUTH
ACROSS WESTERN ONTARIO. THESE SYSTEMS WILL TEND TO MODULATE
MID-LEVEL TEMPS AND INSTABILITY...ESPECIALLY WHEN JUXTAPOSED ATOP
AFTERNOON/EARLY EVENING DIURNAL WARMTH. FORECAST SOUNDINGS CONTINUE
TO INDICATE WEAK/SKINNY MLCAPES OF 200-300 J/KG THIS AFTERNOON...
WITH VISIBLE SATELLITE IMAGERY INDICATING CUMULUS CONGESTUS
DEVELOPMENT ALONG WEAK LOW LEVEL CONVERGENCE AXIS FROM NEAR ROCKFORD
TO THE SOUTHEAST SIDE OF CHICAGO/NORTHWEST INDIANA WHERE THE LAKE
BREEZE BOUNDARY WAS PROVIDING SOME ADDITIONAL CONVERGENCE.
CURRENT WEAK RADAR RETURNS EXPECTED TO CONTINUE TO SLOWLY GROW
THIS AFTERNOON THROUGH PEAK INSTABILITY...RESULTING IN ISOLATED TO
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. WANING
INSTABILITY AFTER SUNSET THIS EVENING WILL ALLOW A DECREASE IN
COVERAGE. SIMILAR TREND EXPECTED TOMORROW...THOUGH ONTARIO SHORT
WAVE LOOKS TO MOVE ACROSS AREA DURING THE MORNING...AS OPPOSED TO
DURING PERIOD OF BETTER INSTABILITY LATER IN THE DAY. THIS MAY
FAVOR SOUTHEAST PARTS OF THE CWA WHERE FORCING WILL DECREASE
LAST...WHILE DAYTIME INSTABILITY DEVELOPS. THESE DIURNAL
SHOWERS/ISOLATED THUNDERSTORMS...TIED TO CONVERGENCE ZONES AS IS
THE CASE TODAY...WILL CONTINUE IN SIMILAR FASHION THURSDAY AS
WELL. OBVIOUSLY...NOT ALL AREAS WILL SEE PRECIP AND THERE WILL BE
MANY DRY HOURS EVEN IN PLACES THAT DO. BY FRIDAY...ADDITIONAL
SHORT WAVE ENERGY WILL DROP INTO THE WESTERN PORTION OF THE TROUGH
FROM THE NORTHERN PLAINS AND WILL EFFECTIVELY RETROGRADE THE LONG
WAVE TROUGH AXIS WESTWARD INTO THE WESTERN LAKES AND
MISSISSIPPI/LOWER OHIO VALLEY AREA. LARGE SCALE HEIGHT FALLS WILL
LEAD TO SLIGHTLY COOLER MID-LEVEL TEMPS WHICH MAY SUPPORT GREATER
COVERAGE IN SHOWERS/THUNDERSTORMS FRIDAY AND SATURDAY BEFORE THE
TROUGH AXIS BECOMES MORE PROGRESSIVE AND MOVES OFF TO THE EAST
SATURDAY NIGHT AND SUNDAY. THUS HAVE MAINTAINED SOMEWHAT HIGHER
CHANCE POPS WITH A GREATER AERIAL COVERAGE FOR THOSE DAYTIME
PERIODS.

SURFACE HIGH PRESSURE THEN BUILDS ACROSS THE AREA SUNDAY...BEFORE
DRIFTING TO THE SOUTHEAST MONDAY AS ANOTHER SHORT WAVE TROUGH
APPROACHES IN NORTHWEST FLOW ALOFT. THIS MID-LEVEL WAVE IS
ACCOMPANIED BY A SURFACE LOW AND COLD FRONT...WHICH RETURNS THE
SHOWER/THUNDERSTORM THREAT FOR MONDAY/TUESDAY OF NEXT WEEK.

AS FOR TEMPS...MID AND UPPER 70S BEING REACHED THIS AFTERNOON WITH
CONSIDERABLE SUNSHINE. MID-LEVEL TEMPS CONTINUE TO MODERATE VERY
SLOWLY THROUGH THE PERIOD...WITH TO SLOWLY WARMING FROM UPPER 70S TO
AROUND 80 TO LOWER 80S OUTSIDE OF LAKE BREEZE AND SHOWERS INTO THE
WEEKEND. COLD FRONTAL PASSAGE LATE MONDAY WILL ALLOW SUBTLE
COOL-DOWN FROM THE NORTH BY TUESDAY.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* LAKE BREEZE EXPECTED WITH NE WINDS AT 10 KT BEHIND IT.

* SCT SHRA THIS AFTN AND EVENING. A FEW TSRA PSBL.

JEE

//DISCUSSION...UPDATED 06Z...

SHOWERS HAVE PUSHED SOUTH OF THE TERMINALS BUT TODAY IS LOOKING
VERY SIMILAR TO YESTERDAY. A LAKE BREEZE IS EXPECTED ALONG WITH A
WEAKER UPPER LEVEL WAVE. THE LAKE BREEZE WILL PROVIDE ENOUGH
FORCING FOR SCT SHRA THIS AFTN AND EVENING...BUT THINKING WE WILL
SEE LESS ACTIVITY THAN YESTERDAY. A FEW THUNDERSTORMS ARE ALSO
EXPECTED AS WELL BUT THEY SHOULD BE ISOLATED ENOUGH TO LEAVE OUT
OF THE TAF FOR NOW.

WINDS BECOME NE ARND 10 KT BEHIND THE LAKE BREEZE AT MDW AND
ORD....AND NNE AT GYY. HAVE HIGH CONFIDENCE THAT THE LAKE BREEZE
WILL MAKE IT THROUGH MDW AND GYY AND MEDIUM-HIGH CONFIDENCE ABOUT
ORD. WINDS SLOWLY RETURN TO THE SW IN THE EVENING WITH CONTINUED
VFR CONDITIONS.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* HIGH CONFIDENCE IN LAKE BREEZE...MEDIUM CONFIDENCE IN
  TIMING...MEDIUM CONFIDENCE IN HOW FAR INLAND IT TRAVELS.

* MEDIUM-HIGH CONFIDENCE IN SHRA DEVELOPMENT AND COVERAGE...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY...SLIGHT CHANCE TSRA IN AFTN

FRIDAY...SLIGHT CHANCE TSRA IN AFTN

SATURDAY...CHANCE TSRA

SUNDAY...VFR

MONDAY...SLIGHT CHANCE TSRA

DANIELSON/RODRIGUEZ

&&

.MARINE...
255 AM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE WITH A WEAK COLD
FRONT/UPPER LEVEL WAVE MOVING DOWN THE LAKE EARLY THIS MORNING.
WINDS BECOME NORTH AROUND 10 KT BEHIND THE FRONT. HIGH PRESSURE
OVER THE PLAINS ATTEMPTS TO SPREAD EAST TODAY LEADING TO A
CONTINUED VERY WEAK PRESSURE GRADIENT. ONSHORE FLOW IS EXPECTED
ACROSS NEARSHORE AREAS LEADING TO VARIABLE WINDS 10 KT OR LESS AT
TIMES OVER THE OPEN WATERS. WINDS BECOME MORE UNIFORM THIS EVENING
WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY MORNING. A
COUPLE MORE WEAK COOL FRONTS ARE EXPECTED BY WEEKS END...AT THIS
TIME THURSDAY NIGHT AND AGAIN FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS AND SOME STORMS MAINLY DRIVEN BY THE HEATING OF
THE DAY OVER LAND. SOME OF THESE COULD BE ABLE TO MOVE INTO
NEARSHORE AREAS ON THE WESTERN SIDE OF THE LAKE AS SEEN OVER WI/IL
SHORES LAST EVENING...AND PROFILES OVER LAND DO SUPPORT SOME QUICK
RACING OUTFLOWS/GUST FRONTS FROM SHOWERS THE NEXT FEW DAYS...SO
SOMETHING FOR NEARSHORE MARINERS TO KEEP SOME TABS ON DESPITE THE
MAINLY QUIET WIND/WAVE REGIME.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 300756
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
256 AM CDT WED JUL 30 2014

.DISCUSSION...
218 PM CDT

FORECAST ISSUES CONTINUE TO FOCUS ON DAILY DIURNAL ISOLATED TO
SCATTERED SHOWER/THUNDERSTORM CHANCES...WITH VERY GRADUAL WARM UP IN
TEMPERATURES THROUGH THE FORECAST PERIOD AS LONG WAVE UPPER TROUGH
OVER EASTERN NORTH AMERICA EFFECTIVELY RETROGRADES THROUGH THE END
OF THE WEEK BEFORE FINALLY WEAKENING AND PROGRESSING OFF TO THE
NORTHEAST BY LATE WEEKEND AND EARLY NEXT WEEK.

WESTERN GREAT LAKES REGION REMAINS IN WESTERN PERIPHERY OF THIS
AFOREMENTIONED TROUGH...WITHIN REGION OF BROAD CYCLONIC CIRCULATION.
SERIES OF RELATIVELY MINOR SHORT WAVES WILL CONTINUE TO RIPPLE
SOUTH-SOUTHEAST THROUGH THE FLOW ACROSS THE AREA THROUGH THE
REMAINDER OF THE WEEK. GOES WATER VAPOR IMAGERY INDICATES A COUPLE
OF WEAK RIPPLES PASSED ACROSS THE REGION THIS MORNING...WITH A
SOMEWHAT MORE ROBUST SHORT WAVE NOTED UPSTREAM PROPAGATING SOUTH
ACROSS WESTERN ONTARIO. THESE SYSTEMS WILL TEND TO MODULATE
MID-LEVEL TEMPS AND INSTABILITY...ESPECIALLY WHEN JUXTAPOSED ATOP
AFTERNOON/EARLY EVENING DIURNAL WARMTH. FORECAST SOUNDINGS CONTINUE
TO INDICATE WEAK/SKINNY MLCAPES OF 200-300 J/KG THIS AFTERNOON...
WITH VISIBLE SATELLITE IMAGERY INDICATING CUMULUS CONGESTUS
DEVELOPMENT ALONG WEAK LOW LEVEL CONVERGENCE AXIS FROM NEAR ROCKFORD
TO THE SOUTHEAST SIDE OF CHICAGO/NORTHWEST INDIANA WHERE THE LAKE
BREEZE BOUNDARY WAS PROVIDING SOME ADDITIONAL CONVERGENCE.
CURRENT WEAK RADAR RETURNS EXPECTED TO CONTINUE TO SLOWLY GROW
THIS AFTERNOON THROUGH PEAK INSTABILITY...RESULTING IN ISOLATED TO
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. WANING
INSTABILITY AFTER SUNSET THIS EVENING WILL ALLOW A DECREASE IN
COVERAGE. SIMILAR TREND EXPECTED TOMORROW...THOUGH ONTARIO SHORT
WAVE LOOKS TO MOVE ACROSS AREA DURING THE MORNING...AS OPPOSED TO
DURING PERIOD OF BETTER INSTABILITY LATER IN THE DAY. THIS MAY
FAVOR SOUTHEAST PARTS OF THE CWA WHERE FORCING WILL DECREASE
LAST...WHILE DAYTIME INSTABILITY DEVELOPS. THESE DIURNAL
SHOWERS/ISOLATED THUNDERSTORMS...TIED TO CONVERGENCE ZONES AS IS
THE CASE TODAY...WILL CONTINUE IN SIMILAR FASHION THURSDAY AS
WELL. OBVIOUSLY...NOT ALL AREAS WILL SEE PRECIP AND THERE WILL BE
MANY DRY HOURS EVEN IN PLACES THAT DO. BY FRIDAY...ADDITIONAL
SHORT WAVE ENERGY WILL DROP INTO THE WESTERN PORTION OF THE TROUGH
FROM THE NORTHERN PLAINS AND WILL EFFECTIVELY RETROGRADE THE LONG
WAVE TROUGH AXIS WESTWARD INTO THE WESTERN LAKES AND
MISSISSIPPI/LOWER OHIO VALLEY AREA. LARGE SCALE HEIGHT FALLS WILL
LEAD TO SLIGHTLY COOLER MID-LEVEL TEMPS WHICH MAY SUPPORT GREATER
COVERAGE IN SHOWERS/THUNDERSTORMS FRIDAY AND SATURDAY BEFORE THE
TROUGH AXIS BECOMES MORE PROGRESSIVE AND MOVES OFF TO THE EAST
SATURDAY NIGHT AND SUNDAY. THUS HAVE MAINTAINED SOMEWHAT HIGHER
CHANCE POPS WITH A GREATER AERIAL COVERAGE FOR THOSE DAYTIME
PERIODS.

SURFACE HIGH PRESSURE THEN BUILDS ACROSS THE AREA SUNDAY...BEFORE
DRIFTING TO THE SOUTHEAST MONDAY AS ANOTHER SHORT WAVE TROUGH
APPROACHES IN NORTHWEST FLOW ALOFT. THIS MID-LEVEL WAVE IS
ACCOMPANIED BY A SURFACE LOW AND COLD FRONT...WHICH RETURNS THE
SHOWER/THUNDERSTORM THREAT FOR MONDAY/TUESDAY OF NEXT WEEK.

AS FOR TEMPS...MID AND UPPER 70S BEING REACHED THIS AFTERNOON WITH
CONSIDERABLE SUNSHINE. MID-LEVEL TEMPS CONTINUE TO MODERATE VERY
SLOWLY THROUGH THE PERIOD...WITH TO SLOWLY WARMING FROM UPPER 70S TO
AROUND 80 TO LOWER 80S OUTSIDE OF LAKE BREEZE AND SHOWERS INTO THE
WEEKEND. COLD FRONTAL PASSAGE LATE MONDAY WILL ALLOW SUBTLE
COOL-DOWN FROM THE NORTH BY TUESDAY.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* LAKE BREEZE EXPECTED WITH NE WINDS AT 10 KT BEHIND IT.

* SCT SHRA THIS AFTN AND EVENING. A FEW TSRA PSBL.

JEE

//DISCUSSION...UPDATED 06Z...

SHOWERS HAVE PUSHED SOUTH OF THE TERMINALS BUT TODAY IS LOOKING
VERY SIMILAR TO YESTERDAY. A LAKE BREEZE IS EXPECTED ALONG WITH A
WEAKER UPPER LEVEL WAVE. THE LAKE BREEZE WILL PROVIDE ENOUGH
FORCING FOR SCT SHRA THIS AFTN AND EVENING...BUT THINKING WE WILL
SEE LESS ACTIVITY THAN YESTERDAY. A FEW THUNDERSTORMS ARE ALSO
EXPECTED AS WELL BUT THEY SHOULD BE ISOLATED ENOUGH TO LEAVE OUT
OF THE TAF FOR NOW.

WINDS BECOME NE ARND 10 KT BEHIND THE LAKE BREEZE AT MDW AND
ORD....AND NNE AT GYY. HAVE HIGH CONFIDENCE THAT THE LAKE BREEZE
WILL MAKE IT THROUGH MDW AND GYY AND MEDIUM-HIGH CONFIDENCE ABOUT
ORD. WINDS SLOWLY RETURN TO THE SW IN THE EVENING WITH CONTINUED
VFR CONDITIONS.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* HIGH CONFIDENCE IN LAKE BREEZE...MEDIUM CONFIDENCE IN
  TIMING...MEDIUM CONFIDENCE IN HOW FAR INLAND IT TRAVELS.

* MEDIUM-HIGH CONFIDENCE IN SHRA DEVELOPMENT AND COVERAGE...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY...SLIGHT CHANCE TSRA IN AFTN

FRIDAY...SLIGHT CHANCE TSRA IN AFTN

SATURDAY...CHANCE TSRA

SUNDAY...VFR

MONDAY...SLIGHT CHANCE TSRA

DANIELSON/RODRIGUEZ

&&

.MARINE...
255 AM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE WITH A WEAK COLD
FRONT/UPPER LEVEL WAVE MOVING DOWN THE LAKE EARLY THIS MORNING.
WINDS BECOME NORTH AROUND 10 KT BEHIND THE FRONT. HIGH PRESSURE
OVER THE PLAINS ATTEMPTS TO SPREAD EAST TODAY LEADING TO A
CONTINUED VERY WEAK PRESSURE GRADIENT. ONSHORE FLOW IS EXPECTED
ACROSS NEARSHORE AREAS LEADING TO VARIABLE WINDS 10 KT OR LESS AT
TIMES OVER THE OPEN WATERS. WINDS BECOME MORE UNIFORM THIS EVENING
WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY MORNING. A
COUPLE MORE WEAK COOL FRONTS ARE EXPECTED BY WEEKS END...AT THIS
TIME THURSDAY NIGHT AND AGAIN FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS AND SOME STORMS MAINLY DRIVEN BY THE HEATING OF
THE DAY OVER LAND. SOME OF THESE COULD BE ABLE TO MOVE INTO
NEARSHORE AREAS ON THE WESTERN SIDE OF THE LAKE AS SEEN OVER WI/IL
SHORES LAST EVENING...AND PROFILES OVER LAND DO SUPPORT SOME QUICK
RACING OUTFLOWS/GUST FRONTS FROM SHOWERS THE NEXT FEW DAYS...SO
SOMETHING FOR NEARSHORE MARINERS TO KEEP SOME TABS ON DESPITE THE
MAINLY QUIET WIND/WAVE REGIME.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 300756
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
256 AM CDT WED JUL 30 2014

.DISCUSSION...
218 PM CDT

FORECAST ISSUES CONTINUE TO FOCUS ON DAILY DIURNAL ISOLATED TO
SCATTERED SHOWER/THUNDERSTORM CHANCES...WITH VERY GRADUAL WARM UP IN
TEMPERATURES THROUGH THE FORECAST PERIOD AS LONG WAVE UPPER TROUGH
OVER EASTERN NORTH AMERICA EFFECTIVELY RETROGRADES THROUGH THE END
OF THE WEEK BEFORE FINALLY WEAKENING AND PROGRESSING OFF TO THE
NORTHEAST BY LATE WEEKEND AND EARLY NEXT WEEK.

WESTERN GREAT LAKES REGION REMAINS IN WESTERN PERIPHERY OF THIS
AFOREMENTIONED TROUGH...WITHIN REGION OF BROAD CYCLONIC CIRCULATION.
SERIES OF RELATIVELY MINOR SHORT WAVES WILL CONTINUE TO RIPPLE
SOUTH-SOUTHEAST THROUGH THE FLOW ACROSS THE AREA THROUGH THE
REMAINDER OF THE WEEK. GOES WATER VAPOR IMAGERY INDICATES A COUPLE
OF WEAK RIPPLES PASSED ACROSS THE REGION THIS MORNING...WITH A
SOMEWHAT MORE ROBUST SHORT WAVE NOTED UPSTREAM PROPAGATING SOUTH
ACROSS WESTERN ONTARIO. THESE SYSTEMS WILL TEND TO MODULATE
MID-LEVEL TEMPS AND INSTABILITY...ESPECIALLY WHEN JUXTAPOSED ATOP
AFTERNOON/EARLY EVENING DIURNAL WARMTH. FORECAST SOUNDINGS CONTINUE
TO INDICATE WEAK/SKINNY MLCAPES OF 200-300 J/KG THIS AFTERNOON...
WITH VISIBLE SATELLITE IMAGERY INDICATING CUMULUS CONGESTUS
DEVELOPMENT ALONG WEAK LOW LEVEL CONVERGENCE AXIS FROM NEAR ROCKFORD
TO THE SOUTHEAST SIDE OF CHICAGO/NORTHWEST INDIANA WHERE THE LAKE
BREEZE BOUNDARY WAS PROVIDING SOME ADDITIONAL CONVERGENCE.
CURRENT WEAK RADAR RETURNS EXPECTED TO CONTINUE TO SLOWLY GROW
THIS AFTERNOON THROUGH PEAK INSTABILITY...RESULTING IN ISOLATED TO
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. WANING
INSTABILITY AFTER SUNSET THIS EVENING WILL ALLOW A DECREASE IN
COVERAGE. SIMILAR TREND EXPECTED TOMORROW...THOUGH ONTARIO SHORT
WAVE LOOKS TO MOVE ACROSS AREA DURING THE MORNING...AS OPPOSED TO
DURING PERIOD OF BETTER INSTABILITY LATER IN THE DAY. THIS MAY
FAVOR SOUTHEAST PARTS OF THE CWA WHERE FORCING WILL DECREASE
LAST...WHILE DAYTIME INSTABILITY DEVELOPS. THESE DIURNAL
SHOWERS/ISOLATED THUNDERSTORMS...TIED TO CONVERGENCE ZONES AS IS
THE CASE TODAY...WILL CONTINUE IN SIMILAR FASHION THURSDAY AS
WELL. OBVIOUSLY...NOT ALL AREAS WILL SEE PRECIP AND THERE WILL BE
MANY DRY HOURS EVEN IN PLACES THAT DO. BY FRIDAY...ADDITIONAL
SHORT WAVE ENERGY WILL DROP INTO THE WESTERN PORTION OF THE TROUGH
FROM THE NORTHERN PLAINS AND WILL EFFECTIVELY RETROGRADE THE LONG
WAVE TROUGH AXIS WESTWARD INTO THE WESTERN LAKES AND
MISSISSIPPI/LOWER OHIO VALLEY AREA. LARGE SCALE HEIGHT FALLS WILL
LEAD TO SLIGHTLY COOLER MID-LEVEL TEMPS WHICH MAY SUPPORT GREATER
COVERAGE IN SHOWERS/THUNDERSTORMS FRIDAY AND SATURDAY BEFORE THE
TROUGH AXIS BECOMES MORE PROGRESSIVE AND MOVES OFF TO THE EAST
SATURDAY NIGHT AND SUNDAY. THUS HAVE MAINTAINED SOMEWHAT HIGHER
CHANCE POPS WITH A GREATER AERIAL COVERAGE FOR THOSE DAYTIME
PERIODS.

SURFACE HIGH PRESSURE THEN BUILDS ACROSS THE AREA SUNDAY...BEFORE
DRIFTING TO THE SOUTHEAST MONDAY AS ANOTHER SHORT WAVE TROUGH
APPROACHES IN NORTHWEST FLOW ALOFT. THIS MID-LEVEL WAVE IS
ACCOMPANIED BY A SURFACE LOW AND COLD FRONT...WHICH RETURNS THE
SHOWER/THUNDERSTORM THREAT FOR MONDAY/TUESDAY OF NEXT WEEK.

AS FOR TEMPS...MID AND UPPER 70S BEING REACHED THIS AFTERNOON WITH
CONSIDERABLE SUNSHINE. MID-LEVEL TEMPS CONTINUE TO MODERATE VERY
SLOWLY THROUGH THE PERIOD...WITH TO SLOWLY WARMING FROM UPPER 70S TO
AROUND 80 TO LOWER 80S OUTSIDE OF LAKE BREEZE AND SHOWERS INTO THE
WEEKEND. COLD FRONTAL PASSAGE LATE MONDAY WILL ALLOW SUBTLE
COOL-DOWN FROM THE NORTH BY TUESDAY.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* LAKE BREEZE EXPECTED WITH NE WINDS AT 10 KT BEHIND IT.

* SCT SHRA THIS AFTN AND EVENING. A FEW TSRA PSBL.

JEE

//DISCUSSION...UPDATED 06Z...

SHOWERS HAVE PUSHED SOUTH OF THE TERMINALS BUT TODAY IS LOOKING
VERY SIMILAR TO YESTERDAY. A LAKE BREEZE IS EXPECTED ALONG WITH A
WEAKER UPPER LEVEL WAVE. THE LAKE BREEZE WILL PROVIDE ENOUGH
FORCING FOR SCT SHRA THIS AFTN AND EVENING...BUT THINKING WE WILL
SEE LESS ACTIVITY THAN YESTERDAY. A FEW THUNDERSTORMS ARE ALSO
EXPECTED AS WELL BUT THEY SHOULD BE ISOLATED ENOUGH TO LEAVE OUT
OF THE TAF FOR NOW.

WINDS BECOME NE ARND 10 KT BEHIND THE LAKE BREEZE AT MDW AND
ORD....AND NNE AT GYY. HAVE HIGH CONFIDENCE THAT THE LAKE BREEZE
WILL MAKE IT THROUGH MDW AND GYY AND MEDIUM-HIGH CONFIDENCE ABOUT
ORD. WINDS SLOWLY RETURN TO THE SW IN THE EVENING WITH CONTINUED
VFR CONDITIONS.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* HIGH CONFIDENCE IN LAKE BREEZE...MEDIUM CONFIDENCE IN
  TIMING...MEDIUM CONFIDENCE IN HOW FAR INLAND IT TRAVELS.

* MEDIUM-HIGH CONFIDENCE IN SHRA DEVELOPMENT AND COVERAGE...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY...SLIGHT CHANCE TSRA IN AFTN

FRIDAY...SLIGHT CHANCE TSRA IN AFTN

SATURDAY...CHANCE TSRA

SUNDAY...VFR

MONDAY...SLIGHT CHANCE TSRA

DANIELSON/RODRIGUEZ

&&

.MARINE...
255 AM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE WITH A WEAK COLD
FRONT/UPPER LEVEL WAVE MOVING DOWN THE LAKE EARLY THIS MORNING.
WINDS BECOME NORTH AROUND 10 KT BEHIND THE FRONT. HIGH PRESSURE
OVER THE PLAINS ATTEMPTS TO SPREAD EAST TODAY LEADING TO A
CONTINUED VERY WEAK PRESSURE GRADIENT. ONSHORE FLOW IS EXPECTED
ACROSS NEARSHORE AREAS LEADING TO VARIABLE WINDS 10 KT OR LESS AT
TIMES OVER THE OPEN WATERS. WINDS BECOME MORE UNIFORM THIS EVENING
WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY MORNING. A
COUPLE MORE WEAK COOL FRONTS ARE EXPECTED BY WEEKS END...AT THIS
TIME THURSDAY NIGHT AND AGAIN FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS AND SOME STORMS MAINLY DRIVEN BY THE HEATING OF
THE DAY OVER LAND. SOME OF THESE COULD BE ABLE TO MOVE INTO
NEARSHORE AREAS ON THE WESTERN SIDE OF THE LAKE AS SEEN OVER WI/IL
SHORES LAST EVENING...AND PROFILES OVER LAND DO SUPPORT SOME QUICK
RACING OUTFLOWS/GUST FRONTS FROM SHOWERS THE NEXT FEW DAYS...SO
SOMETHING FOR NEARSHORE MARINERS TO KEEP SOME TABS ON DESPITE THE
MAINLY QUIET WIND/WAVE REGIME.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 300756
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
256 AM CDT WED JUL 30 2014

.DISCUSSION...
218 PM CDT

FORECAST ISSUES CONTINUE TO FOCUS ON DAILY DIURNAL ISOLATED TO
SCATTERED SHOWER/THUNDERSTORM CHANCES...WITH VERY GRADUAL WARM UP IN
TEMPERATURES THROUGH THE FORECAST PERIOD AS LONG WAVE UPPER TROUGH
OVER EASTERN NORTH AMERICA EFFECTIVELY RETROGRADES THROUGH THE END
OF THE WEEK BEFORE FINALLY WEAKENING AND PROGRESSING OFF TO THE
NORTHEAST BY LATE WEEKEND AND EARLY NEXT WEEK.

WESTERN GREAT LAKES REGION REMAINS IN WESTERN PERIPHERY OF THIS
AFOREMENTIONED TROUGH...WITHIN REGION OF BROAD CYCLONIC CIRCULATION.
SERIES OF RELATIVELY MINOR SHORT WAVES WILL CONTINUE TO RIPPLE
SOUTH-SOUTHEAST THROUGH THE FLOW ACROSS THE AREA THROUGH THE
REMAINDER OF THE WEEK. GOES WATER VAPOR IMAGERY INDICATES A COUPLE
OF WEAK RIPPLES PASSED ACROSS THE REGION THIS MORNING...WITH A
SOMEWHAT MORE ROBUST SHORT WAVE NOTED UPSTREAM PROPAGATING SOUTH
ACROSS WESTERN ONTARIO. THESE SYSTEMS WILL TEND TO MODULATE
MID-LEVEL TEMPS AND INSTABILITY...ESPECIALLY WHEN JUXTAPOSED ATOP
AFTERNOON/EARLY EVENING DIURNAL WARMTH. FORECAST SOUNDINGS CONTINUE
TO INDICATE WEAK/SKINNY MLCAPES OF 200-300 J/KG THIS AFTERNOON...
WITH VISIBLE SATELLITE IMAGERY INDICATING CUMULUS CONGESTUS
DEVELOPMENT ALONG WEAK LOW LEVEL CONVERGENCE AXIS FROM NEAR ROCKFORD
TO THE SOUTHEAST SIDE OF CHICAGO/NORTHWEST INDIANA WHERE THE LAKE
BREEZE BOUNDARY WAS PROVIDING SOME ADDITIONAL CONVERGENCE.
CURRENT WEAK RADAR RETURNS EXPECTED TO CONTINUE TO SLOWLY GROW
THIS AFTERNOON THROUGH PEAK INSTABILITY...RESULTING IN ISOLATED TO
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. WANING
INSTABILITY AFTER SUNSET THIS EVENING WILL ALLOW A DECREASE IN
COVERAGE. SIMILAR TREND EXPECTED TOMORROW...THOUGH ONTARIO SHORT
WAVE LOOKS TO MOVE ACROSS AREA DURING THE MORNING...AS OPPOSED TO
DURING PERIOD OF BETTER INSTABILITY LATER IN THE DAY. THIS MAY
FAVOR SOUTHEAST PARTS OF THE CWA WHERE FORCING WILL DECREASE
LAST...WHILE DAYTIME INSTABILITY DEVELOPS. THESE DIURNAL
SHOWERS/ISOLATED THUNDERSTORMS...TIED TO CONVERGENCE ZONES AS IS
THE CASE TODAY...WILL CONTINUE IN SIMILAR FASHION THURSDAY AS
WELL. OBVIOUSLY...NOT ALL AREAS WILL SEE PRECIP AND THERE WILL BE
MANY DRY HOURS EVEN IN PLACES THAT DO. BY FRIDAY...ADDITIONAL
SHORT WAVE ENERGY WILL DROP INTO THE WESTERN PORTION OF THE TROUGH
FROM THE NORTHERN PLAINS AND WILL EFFECTIVELY RETROGRADE THE LONG
WAVE TROUGH AXIS WESTWARD INTO THE WESTERN LAKES AND
MISSISSIPPI/LOWER OHIO VALLEY AREA. LARGE SCALE HEIGHT FALLS WILL
LEAD TO SLIGHTLY COOLER MID-LEVEL TEMPS WHICH MAY SUPPORT GREATER
COVERAGE IN SHOWERS/THUNDERSTORMS FRIDAY AND SATURDAY BEFORE THE
TROUGH AXIS BECOMES MORE PROGRESSIVE AND MOVES OFF TO THE EAST
SATURDAY NIGHT AND SUNDAY. THUS HAVE MAINTAINED SOMEWHAT HIGHER
CHANCE POPS WITH A GREATER AERIAL COVERAGE FOR THOSE DAYTIME
PERIODS.

SURFACE HIGH PRESSURE THEN BUILDS ACROSS THE AREA SUNDAY...BEFORE
DRIFTING TO THE SOUTHEAST MONDAY AS ANOTHER SHORT WAVE TROUGH
APPROACHES IN NORTHWEST FLOW ALOFT. THIS MID-LEVEL WAVE IS
ACCOMPANIED BY A SURFACE LOW AND COLD FRONT...WHICH RETURNS THE
SHOWER/THUNDERSTORM THREAT FOR MONDAY/TUESDAY OF NEXT WEEK.

AS FOR TEMPS...MID AND UPPER 70S BEING REACHED THIS AFTERNOON WITH
CONSIDERABLE SUNSHINE. MID-LEVEL TEMPS CONTINUE TO MODERATE VERY
SLOWLY THROUGH THE PERIOD...WITH TO SLOWLY WARMING FROM UPPER 70S TO
AROUND 80 TO LOWER 80S OUTSIDE OF LAKE BREEZE AND SHOWERS INTO THE
WEEKEND. COLD FRONTAL PASSAGE LATE MONDAY WILL ALLOW SUBTLE
COOL-DOWN FROM THE NORTH BY TUESDAY.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* LAKE BREEZE EXPECTED WITH NE WINDS AT 10 KT BEHIND IT.

* SCT SHRA THIS AFTN AND EVENING. A FEW TSRA PSBL.

JEE

//DISCUSSION...UPDATED 06Z...

SHOWERS HAVE PUSHED SOUTH OF THE TERMINALS BUT TODAY IS LOOKING
VERY SIMILAR TO YESTERDAY. A LAKE BREEZE IS EXPECTED ALONG WITH A
WEAKER UPPER LEVEL WAVE. THE LAKE BREEZE WILL PROVIDE ENOUGH
FORCING FOR SCT SHRA THIS AFTN AND EVENING...BUT THINKING WE WILL
SEE LESS ACTIVITY THAN YESTERDAY. A FEW THUNDERSTORMS ARE ALSO
EXPECTED AS WELL BUT THEY SHOULD BE ISOLATED ENOUGH TO LEAVE OUT
OF THE TAF FOR NOW.

WINDS BECOME NE ARND 10 KT BEHIND THE LAKE BREEZE AT MDW AND
ORD....AND NNE AT GYY. HAVE HIGH CONFIDENCE THAT THE LAKE BREEZE
WILL MAKE IT THROUGH MDW AND GYY AND MEDIUM-HIGH CONFIDENCE ABOUT
ORD. WINDS SLOWLY RETURN TO THE SW IN THE EVENING WITH CONTINUED
VFR CONDITIONS.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* HIGH CONFIDENCE IN LAKE BREEZE...MEDIUM CONFIDENCE IN
  TIMING...MEDIUM CONFIDENCE IN HOW FAR INLAND IT TRAVELS.

* MEDIUM-HIGH CONFIDENCE IN SHRA DEVELOPMENT AND COVERAGE...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY...SLIGHT CHANCE TSRA IN AFTN

FRIDAY...SLIGHT CHANCE TSRA IN AFTN

SATURDAY...CHANCE TSRA

SUNDAY...VFR

MONDAY...SLIGHT CHANCE TSRA

DANIELSON/RODRIGUEZ

&&

.MARINE...
255 AM CDT

A WEAK PRESSURE GRADIENT IS OVER THE LAKE WITH A WEAK COLD
FRONT/UPPER LEVEL WAVE MOVING DOWN THE LAKE EARLY THIS MORNING.
WINDS BECOME NORTH AROUND 10 KT BEHIND THE FRONT. HIGH PRESSURE
OVER THE PLAINS ATTEMPTS TO SPREAD EAST TODAY LEADING TO A
CONTINUED VERY WEAK PRESSURE GRADIENT. ONSHORE FLOW IS EXPECTED
ACROSS NEARSHORE AREAS LEADING TO VARIABLE WINDS 10 KT OR LESS AT
TIMES OVER THE OPEN WATERS. WINDS BECOME MORE UNIFORM THIS EVENING
WITH SOUTHWEST WINDS ACROSS THE LAKE BY EARLY THURSDAY MORNING. A
COUPLE MORE WEAK COOL FRONTS ARE EXPECTED BY WEEKS END...AT THIS
TIME THURSDAY NIGHT AND AGAIN FRIDAY NIGHT INTO EARLY SATURDAY.
EACH OF THESE WILL TURN SOUTHWEST WINDS TO THE NORTHWEST/NORTH BUT
SPEEDS PRIMARILY REMAINING BELOW 15 KT.

THE GREAT LAKES REGION WILL LIKELY EXPERIENCE AFTERNOON AND EARLY
EVENING SHOWERS AND SOME STORMS MAINLY DRIVEN BY THE HEATING OF
THE DAY OVER LAND. SOME OF THESE COULD BE ABLE TO MOVE INTO
NEARSHORE AREAS ON THE WESTERN SIDE OF THE LAKE AS SEEN OVER WI/IL
SHORES LAST EVENING...AND PROFILES OVER LAND DO SUPPORT SOME QUICK
RACING OUTFLOWS/GUST FRONTS FROM SHOWERS THE NEXT FEW DAYS...SO
SOMETHING FOR NEARSHORE MARINERS TO KEEP SOME TABS ON DESPITE THE
MAINLY QUIET WIND/WAVE REGIME.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 300548
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1248 AM CDT WED JUL 30 2014

.DISCUSSION...
218 PM CDT

FORECAST ISSUES CONTINUE TO FOCUS ON DAILY DIURNAL ISOLATED TO
SCATTERED SHOWER/THUNDERSTORM CHANCES...WITH VERY GRADUAL WARM UP IN
TEMPERATURES THROUGH THE FORECAST PERIOD AS LONG WAVE UPPER TROUGH
OVER EASTERN NORTH AMERICA EFFECTIVELY RETROGRADES THROUGH THE END
OF THE WEEK BEFORE FINALLY WEAKENING AND PROGRESSING OFF TO THE
NORTHEAST BY LATE WEEKEND AND EARLY NEXT WEEK.

WESTERN GREAT LAKES REGION REMAINS IN WESTERN PERIPHERY OF THIS
AFOREMENTIONED TROUGH...WITHIN REGION OF BROAD CYCLONIC CIRCULATION.
SERIES OF RELATIVELY MINOR SHORT WAVES WILL CONTINUE TO RIPPLE
SOUTH-SOUTHEAST THROUGH THE FLOW ACROSS THE AREA THROUGH THE
REMAINDER OF THE WEEK. GOES WATER VAPOR IMAGERY INDICATES A COUPLE
OF WEAK RIPPLES PASSED ACROSS THE REGION THIS MORNING...WITH A
SOMEWHAT MORE ROBUST SHORT WAVE NOTED UPSTREAM PROPAGATING SOUTH
ACROSS WESTERN ONTARIO. THESE SYSTEMS WILL TEND TO MODULATE
MID-LEVEL TEMPS AND INSTABILITY...ESPECIALLY WHEN JUXTAPOSED ATOP
AFTERNOON/EARLY EVENING DIURNAL WARMTH. FORECAST SOUNDINGS CONTINUE
TO INDICATE WEAK/SKINNY MLCAPES OF 200-300 J/KG THIS AFTERNOON...
WITH VISIBLE SATELLITE IMAGERY INDICATING CUMULUS CONGESTUS
DEVELOPMENT ALONG WEAK LOW LEVEL CONVERGENCE AXIS FROM NEAR ROCKFORD
TO THE SOUTHEAST SIDE OF CHICAGO/NORTHWEST INDIANA WHERE THE LAKE
BREEZE BOUNDARY WAS PROVIDING SOME ADDITIONAL CONVERGENCE.
CURRENT WEAK RADAR RETURNS EXPECTED TO CONTINUE TO SLOWLY GROW
THIS AFTERNOON THROUGH PEAK INSTABILITY...RESULTING IN ISOLATED TO
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. WANING
INSTABILITY AFTER SUNSET THIS EVENING WILL ALLOW A DECREASE IN
COVERAGE. SIMILAR TREND EXPECTED TOMORROW...THOUGH ONTARIO SHORT
WAVE LOOKS TO MOVE ACROSS AREA DURING THE MORNING...AS OPPOSED TO
DURING PERIOD OF BETTER INSTABILITY LATER IN THE DAY. THIS MAY
FAVOR SOUTHEAST PARTS OF THE CWA WHERE FORCING WILL DECREASE
LAST...WHILE DAYTIME INSTABILITY DEVELOPS. THESE DIURNAL
SHOWERS/ISOLATED THUNDERSTORMS...TIED TO CONVERGENCE ZONES AS IS
THE CASE TODAY...WILL CONTINUE IN SIMILAR FASHION THURSDAY AS
WELL. OBVIOUSLY...NOT ALL AREAS WILL SEE PRECIP AND THERE WILL BE
MANY DRY HOURS EVEN IN PLACES THAT DO. BY FRIDAY...ADDITIONAL
SHORT WAVE ENERGY WILL DROP INTO THE WESTERN PORTION OF THE TROUGH
FROM THE NORTHERN PLAINS AND WILL EFFECTIVELY RETROGRADE THE LONG
WAVE TROUGH AXIS WESTWARD INTO THE WESTERN LAKES AND
MISSISSIPPI/LOWER OHIO VALLEY AREA. LARGE SCALE HEIGHT FALLS WILL
LEAD TO SLIGHTLY COOLER MID-LEVEL TEMPS WHICH MAY SUPPORT GREATER
COVERAGE IN SHOWERS/THUNDERSTORMS FRIDAY AND SATURDAY BEFORE THE
TROUGH AXIS BECOMES MORE PROGRESSIVE AND MOVES OFF TO THE EAST
SATURDAY NIGHT AND SUNDAY. THUS HAVE MAINTAINED SOMEWHAT HIGHER
CHANCE POPS WITH A GREATER AERIAL COVERAGE FOR THOSE DAYTIME
PERIODS.

SURFACE HIGH PRESSURE THEN BUILDS ACROSS THE AREA SUNDAY...BEFORE
DRIFTING TO THE SOUTHEAST MONDAY AS ANOTHER SHORT WAVE TROUGH
APPROACHES IN NORTHWEST FLOW ALOFT. THIS MID-LEVEL WAVE IS
ACCOMPANIED BY A SURFACE LOW AND COLD FRONT...WHICH RETURNS THE
SHOWER/THUNDERSTORM THREAT FOR MONDAY/TUESDAY OF NEXT WEEK.

AS FOR TEMPS...MID AND UPPER 70S BEING REACHED THIS AFTERNOON WITH
CONSIDERABLE SUNSHINE. MID-LEVEL TEMPS CONTINUE TO MODERATE VERY
SLOWLY THROUGH THE PERIOD...WITH TO SLOWLY WARMING FROM UPPER 70S TO
AROUND 80 TO LOWER 80S OUTSIDE OF LAKE BREEZE AND SHOWERS INTO THE
WEEKEND. COLD FRONTAL PASSAGE LATE MONDAY WILL ALLOW SUBTLE
COOL-DOWN FROM THE NORTH BY TUESDAY.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* LAKE BREEZE EXPECTED WITH NE WINDS AT 10 KT BEHIND IT.

* SCT SHRA THIS AFTN AND EVENING. A FEW TSRA PSBL.

JEE

//DISCUSSION...UPDATED 06Z...

SHOWERS HAVE PUSHED SOUTH OF THE TERMINALS BUT TODAY IS LOOKING
VERY SIMILAR TO YESTERDAY. A LAKE BREEZE IS EXPECTED ALONG WITH A
WEAKER UPPER LEVEL WAVE. THE LAKE BREEZE WILL PROVIDE ENOUGH
FORCING FOR SCT SHRA THIS AFTN AND EVENING...BUT THINKING WE WILL
SEE LESS ACTIVITY THAN YESTERDAY. A FEW THUNDERSTORMS ARE ALSO
EXPECTED AS WELL BUT THEY SHOULD BE ISOLATED ENOUGH TO LEAVE OUT
OF THE TAF FOR NOW.

WINDS BECOME NE ARND 10 KT BEHIND THE LAKE BREEZE AT MDW AND
ORD....AND NNE AT GYY. HAVE HIGH CONFIDENCE THAT THE LAKE BREEZE
WILL MAKE IT THROUGH MDW AND GYY AND MEDIUM-HIGH CONFIDENCE ABOUT
ORD. WINDS SLOWLY RETURN TO THE SW IN THE EVENING WITH CONTINUED
VFR CONDITIONS.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* HIGH CONFIDENCE IN LAKE BREEZE...MEDIUM CONFIDENCE IN
  TIMING...MEDIUM CONFIDENCE IN HOW FAR INLAND IT TRAVELS.

* MEDIUM-HIGH CONFIDENCE IN SHRA DEVELOPMENT AND COVERAGE...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY...SLIGHT CHANCE TSRA IN AFTN

FRIDAY...SLIGHT CHANCE TSRA IN AFTN

SATURDAY...CHANCE TSRA

SUNDAY...VFR

MONDAY...SLIGHT CHANCE TSRA

DANIELSON/RODRIGUEZ

&&

.MARINE...
210 PM CDT

HIGH PRESSURE IN THE NORTHERN AND CENTRAL PLAINS IS EXPECTED TO
WEAKEN SOME OVER THE COMING DAYS BUT GENERALLY REMAIN STATIONARY FOR
MOST OF THE WEEK AS AN UPPER LEVEL LOW PRESSURE SYSTEMS REMAINS
PARKED OVER JAMES BAY THROUGH SATURDAY. IN THIS PATTERN WEAK LOW
PRESSURE SYSTEMS WILL GLIDE SOUTHEAST DOWN THE LAKE AT TIMES...WITH
THE FIRST EXPECTED LATER TONIGHT INTO EARLY WEDNESDAY.

IN THIS STAGNANT PATTERN THE PRESSURE GRADIENT WILL REMAIN ON THE
LIGHTER SIDE AND WILL PROMOTE THE DEVELOPMENT OF LAKE BREEZES FOR
THE NEARSHORE WATERS AND VARIABLE WINDS OVER MUCH OF THE OPEN LAKE
AND WINDS GENERALLY 15 KT OR LESS.  KMD

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 300548
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1248 AM CDT WED JUL 30 2014

.DISCUSSION...
218 PM CDT

FORECAST ISSUES CONTINUE TO FOCUS ON DAILY DIURNAL ISOLATED TO
SCATTERED SHOWER/THUNDERSTORM CHANCES...WITH VERY GRADUAL WARM UP IN
TEMPERATURES THROUGH THE FORECAST PERIOD AS LONG WAVE UPPER TROUGH
OVER EASTERN NORTH AMERICA EFFECTIVELY RETROGRADES THROUGH THE END
OF THE WEEK BEFORE FINALLY WEAKENING AND PROGRESSING OFF TO THE
NORTHEAST BY LATE WEEKEND AND EARLY NEXT WEEK.

WESTERN GREAT LAKES REGION REMAINS IN WESTERN PERIPHERY OF THIS
AFOREMENTIONED TROUGH...WITHIN REGION OF BROAD CYCLONIC CIRCULATION.
SERIES OF RELATIVELY MINOR SHORT WAVES WILL CONTINUE TO RIPPLE
SOUTH-SOUTHEAST THROUGH THE FLOW ACROSS THE AREA THROUGH THE
REMAINDER OF THE WEEK. GOES WATER VAPOR IMAGERY INDICATES A COUPLE
OF WEAK RIPPLES PASSED ACROSS THE REGION THIS MORNING...WITH A
SOMEWHAT MORE ROBUST SHORT WAVE NOTED UPSTREAM PROPAGATING SOUTH
ACROSS WESTERN ONTARIO. THESE SYSTEMS WILL TEND TO MODULATE
MID-LEVEL TEMPS AND INSTABILITY...ESPECIALLY WHEN JUXTAPOSED ATOP
AFTERNOON/EARLY EVENING DIURNAL WARMTH. FORECAST SOUNDINGS CONTINUE
TO INDICATE WEAK/SKINNY MLCAPES OF 200-300 J/KG THIS AFTERNOON...
WITH VISIBLE SATELLITE IMAGERY INDICATING CUMULUS CONGESTUS
DEVELOPMENT ALONG WEAK LOW LEVEL CONVERGENCE AXIS FROM NEAR ROCKFORD
TO THE SOUTHEAST SIDE OF CHICAGO/NORTHWEST INDIANA WHERE THE LAKE
BREEZE BOUNDARY WAS PROVIDING SOME ADDITIONAL CONVERGENCE.
CURRENT WEAK RADAR RETURNS EXPECTED TO CONTINUE TO SLOWLY GROW
THIS AFTERNOON THROUGH PEAK INSTABILITY...RESULTING IN ISOLATED TO
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. WANING
INSTABILITY AFTER SUNSET THIS EVENING WILL ALLOW A DECREASE IN
COVERAGE. SIMILAR TREND EXPECTED TOMORROW...THOUGH ONTARIO SHORT
WAVE LOOKS TO MOVE ACROSS AREA DURING THE MORNING...AS OPPOSED TO
DURING PERIOD OF BETTER INSTABILITY LATER IN THE DAY. THIS MAY
FAVOR SOUTHEAST PARTS OF THE CWA WHERE FORCING WILL DECREASE
LAST...WHILE DAYTIME INSTABILITY DEVELOPS. THESE DIURNAL
SHOWERS/ISOLATED THUNDERSTORMS...TIED TO CONVERGENCE ZONES AS IS
THE CASE TODAY...WILL CONTINUE IN SIMILAR FASHION THURSDAY AS
WELL. OBVIOUSLY...NOT ALL AREAS WILL SEE PRECIP AND THERE WILL BE
MANY DRY HOURS EVEN IN PLACES THAT DO. BY FRIDAY...ADDITIONAL
SHORT WAVE ENERGY WILL DROP INTO THE WESTERN PORTION OF THE TROUGH
FROM THE NORTHERN PLAINS AND WILL EFFECTIVELY RETROGRADE THE LONG
WAVE TROUGH AXIS WESTWARD INTO THE WESTERN LAKES AND
MISSISSIPPI/LOWER OHIO VALLEY AREA. LARGE SCALE HEIGHT FALLS WILL
LEAD TO SLIGHTLY COOLER MID-LEVEL TEMPS WHICH MAY SUPPORT GREATER
COVERAGE IN SHOWERS/THUNDERSTORMS FRIDAY AND SATURDAY BEFORE THE
TROUGH AXIS BECOMES MORE PROGRESSIVE AND MOVES OFF TO THE EAST
SATURDAY NIGHT AND SUNDAY. THUS HAVE MAINTAINED SOMEWHAT HIGHER
CHANCE POPS WITH A GREATER AERIAL COVERAGE FOR THOSE DAYTIME
PERIODS.

SURFACE HIGH PRESSURE THEN BUILDS ACROSS THE AREA SUNDAY...BEFORE
DRIFTING TO THE SOUTHEAST MONDAY AS ANOTHER SHORT WAVE TROUGH
APPROACHES IN NORTHWEST FLOW ALOFT. THIS MID-LEVEL WAVE IS
ACCOMPANIED BY A SURFACE LOW AND COLD FRONT...WHICH RETURNS THE
SHOWER/THUNDERSTORM THREAT FOR MONDAY/TUESDAY OF NEXT WEEK.

AS FOR TEMPS...MID AND UPPER 70S BEING REACHED THIS AFTERNOON WITH
CONSIDERABLE SUNSHINE. MID-LEVEL TEMPS CONTINUE TO MODERATE VERY
SLOWLY THROUGH THE PERIOD...WITH TO SLOWLY WARMING FROM UPPER 70S TO
AROUND 80 TO LOWER 80S OUTSIDE OF LAKE BREEZE AND SHOWERS INTO THE
WEEKEND. COLD FRONTAL PASSAGE LATE MONDAY WILL ALLOW SUBTLE
COOL-DOWN FROM THE NORTH BY TUESDAY.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* LAKE BREEZE EXPECTED WITH NE WINDS AT 10 KT BEHIND IT.

* SCT SHRA THIS AFTN AND EVENING. A FEW TSRA PSBL.

JEE

//DISCUSSION...UPDATED 06Z...

SHOWERS HAVE PUSHED SOUTH OF THE TERMINALS BUT TODAY IS LOOKING
VERY SIMILAR TO YESTERDAY. A LAKE BREEZE IS EXPECTED ALONG WITH A
WEAKER UPPER LEVEL WAVE. THE LAKE BREEZE WILL PROVIDE ENOUGH
FORCING FOR SCT SHRA THIS AFTN AND EVENING...BUT THINKING WE WILL
SEE LESS ACTIVITY THAN YESTERDAY. A FEW THUNDERSTORMS ARE ALSO
EXPECTED AS WELL BUT THEY SHOULD BE ISOLATED ENOUGH TO LEAVE OUT
OF THE TAF FOR NOW.

WINDS BECOME NE ARND 10 KT BEHIND THE LAKE BREEZE AT MDW AND
ORD....AND NNE AT GYY. HAVE HIGH CONFIDENCE THAT THE LAKE BREEZE
WILL MAKE IT THROUGH MDW AND GYY AND MEDIUM-HIGH CONFIDENCE ABOUT
ORD. WINDS SLOWLY RETURN TO THE SW IN THE EVENING WITH CONTINUED
VFR CONDITIONS.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* HIGH CONFIDENCE IN LAKE BREEZE...MEDIUM CONFIDENCE IN
  TIMING...MEDIUM CONFIDENCE IN HOW FAR INLAND IT TRAVELS.

* MEDIUM-HIGH CONFIDENCE IN SHRA DEVELOPMENT AND COVERAGE...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY...SLIGHT CHANCE TSRA IN AFTN

FRIDAY...SLIGHT CHANCE TSRA IN AFTN

SATURDAY...CHANCE TSRA

SUNDAY...VFR

MONDAY...SLIGHT CHANCE TSRA

DANIELSON/RODRIGUEZ

&&

.MARINE...
210 PM CDT

HIGH PRESSURE IN THE NORTHERN AND CENTRAL PLAINS IS EXPECTED TO
WEAKEN SOME OVER THE COMING DAYS BUT GENERALLY REMAIN STATIONARY FOR
MOST OF THE WEEK AS AN UPPER LEVEL LOW PRESSURE SYSTEMS REMAINS
PARKED OVER JAMES BAY THROUGH SATURDAY. IN THIS PATTERN WEAK LOW
PRESSURE SYSTEMS WILL GLIDE SOUTHEAST DOWN THE LAKE AT TIMES...WITH
THE FIRST EXPECTED LATER TONIGHT INTO EARLY WEDNESDAY.

IN THIS STAGNANT PATTERN THE PRESSURE GRADIENT WILL REMAIN ON THE
LIGHTER SIDE AND WILL PROMOTE THE DEVELOPMENT OF LAKE BREEZES FOR
THE NEARSHORE WATERS AND VARIABLE WINDS OVER MUCH OF THE OPEN LAKE
AND WINDS GENERALLY 15 KT OR LESS.  KMD

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 300548
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1248 AM CDT WED JUL 30 2014

.DISCUSSION...
218 PM CDT

FORECAST ISSUES CONTINUE TO FOCUS ON DAILY DIURNAL ISOLATED TO
SCATTERED SHOWER/THUNDERSTORM CHANCES...WITH VERY GRADUAL WARM UP IN
TEMPERATURES THROUGH THE FORECAST PERIOD AS LONG WAVE UPPER TROUGH
OVER EASTERN NORTH AMERICA EFFECTIVELY RETROGRADES THROUGH THE END
OF THE WEEK BEFORE FINALLY WEAKENING AND PROGRESSING OFF TO THE
NORTHEAST BY LATE WEEKEND AND EARLY NEXT WEEK.

WESTERN GREAT LAKES REGION REMAINS IN WESTERN PERIPHERY OF THIS
AFOREMENTIONED TROUGH...WITHIN REGION OF BROAD CYCLONIC CIRCULATION.
SERIES OF RELATIVELY MINOR SHORT WAVES WILL CONTINUE TO RIPPLE
SOUTH-SOUTHEAST THROUGH THE FLOW ACROSS THE AREA THROUGH THE
REMAINDER OF THE WEEK. GOES WATER VAPOR IMAGERY INDICATES A COUPLE
OF WEAK RIPPLES PASSED ACROSS THE REGION THIS MORNING...WITH A
SOMEWHAT MORE ROBUST SHORT WAVE NOTED UPSTREAM PROPAGATING SOUTH
ACROSS WESTERN ONTARIO. THESE SYSTEMS WILL TEND TO MODULATE
MID-LEVEL TEMPS AND INSTABILITY...ESPECIALLY WHEN JUXTAPOSED ATOP
AFTERNOON/EARLY EVENING DIURNAL WARMTH. FORECAST SOUNDINGS CONTINUE
TO INDICATE WEAK/SKINNY MLCAPES OF 200-300 J/KG THIS AFTERNOON...
WITH VISIBLE SATELLITE IMAGERY INDICATING CUMULUS CONGESTUS
DEVELOPMENT ALONG WEAK LOW LEVEL CONVERGENCE AXIS FROM NEAR ROCKFORD
TO THE SOUTHEAST SIDE OF CHICAGO/NORTHWEST INDIANA WHERE THE LAKE
BREEZE BOUNDARY WAS PROVIDING SOME ADDITIONAL CONVERGENCE.
CURRENT WEAK RADAR RETURNS EXPECTED TO CONTINUE TO SLOWLY GROW
THIS AFTERNOON THROUGH PEAK INSTABILITY...RESULTING IN ISOLATED TO
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. WANING
INSTABILITY AFTER SUNSET THIS EVENING WILL ALLOW A DECREASE IN
COVERAGE. SIMILAR TREND EXPECTED TOMORROW...THOUGH ONTARIO SHORT
WAVE LOOKS TO MOVE ACROSS AREA DURING THE MORNING...AS OPPOSED TO
DURING PERIOD OF BETTER INSTABILITY LATER IN THE DAY. THIS MAY
FAVOR SOUTHEAST PARTS OF THE CWA WHERE FORCING WILL DECREASE
LAST...WHILE DAYTIME INSTABILITY DEVELOPS. THESE DIURNAL
SHOWERS/ISOLATED THUNDERSTORMS...TIED TO CONVERGENCE ZONES AS IS
THE CASE TODAY...WILL CONTINUE IN SIMILAR FASHION THURSDAY AS
WELL. OBVIOUSLY...NOT ALL AREAS WILL SEE PRECIP AND THERE WILL BE
MANY DRY HOURS EVEN IN PLACES THAT DO. BY FRIDAY...ADDITIONAL
SHORT WAVE ENERGY WILL DROP INTO THE WESTERN PORTION OF THE TROUGH
FROM THE NORTHERN PLAINS AND WILL EFFECTIVELY RETROGRADE THE LONG
WAVE TROUGH AXIS WESTWARD INTO THE WESTERN LAKES AND
MISSISSIPPI/LOWER OHIO VALLEY AREA. LARGE SCALE HEIGHT FALLS WILL
LEAD TO SLIGHTLY COOLER MID-LEVEL TEMPS WHICH MAY SUPPORT GREATER
COVERAGE IN SHOWERS/THUNDERSTORMS FRIDAY AND SATURDAY BEFORE THE
TROUGH AXIS BECOMES MORE PROGRESSIVE AND MOVES OFF TO THE EAST
SATURDAY NIGHT AND SUNDAY. THUS HAVE MAINTAINED SOMEWHAT HIGHER
CHANCE POPS WITH A GREATER AERIAL COVERAGE FOR THOSE DAYTIME
PERIODS.

SURFACE HIGH PRESSURE THEN BUILDS ACROSS THE AREA SUNDAY...BEFORE
DRIFTING TO THE SOUTHEAST MONDAY AS ANOTHER SHORT WAVE TROUGH
APPROACHES IN NORTHWEST FLOW ALOFT. THIS MID-LEVEL WAVE IS
ACCOMPANIED BY A SURFACE LOW AND COLD FRONT...WHICH RETURNS THE
SHOWER/THUNDERSTORM THREAT FOR MONDAY/TUESDAY OF NEXT WEEK.

AS FOR TEMPS...MID AND UPPER 70S BEING REACHED THIS AFTERNOON WITH
CONSIDERABLE SUNSHINE. MID-LEVEL TEMPS CONTINUE TO MODERATE VERY
SLOWLY THROUGH THE PERIOD...WITH TO SLOWLY WARMING FROM UPPER 70S TO
AROUND 80 TO LOWER 80S OUTSIDE OF LAKE BREEZE AND SHOWERS INTO THE
WEEKEND. COLD FRONTAL PASSAGE LATE MONDAY WILL ALLOW SUBTLE
COOL-DOWN FROM THE NORTH BY TUESDAY.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* LAKE BREEZE EXPECTED WITH NE WINDS AT 10 KT BEHIND IT.

* SCT SHRA THIS AFTN AND EVENING. A FEW TSRA PSBL.

JEE

//DISCUSSION...UPDATED 06Z...

SHOWERS HAVE PUSHED SOUTH OF THE TERMINALS BUT TODAY IS LOOKING
VERY SIMILAR TO YESTERDAY. A LAKE BREEZE IS EXPECTED ALONG WITH A
WEAKER UPPER LEVEL WAVE. THE LAKE BREEZE WILL PROVIDE ENOUGH
FORCING FOR SCT SHRA THIS AFTN AND EVENING...BUT THINKING WE WILL
SEE LESS ACTIVITY THAN YESTERDAY. A FEW THUNDERSTORMS ARE ALSO
EXPECTED AS WELL BUT THEY SHOULD BE ISOLATED ENOUGH TO LEAVE OUT
OF THE TAF FOR NOW.

WINDS BECOME NE ARND 10 KT BEHIND THE LAKE BREEZE AT MDW AND
ORD....AND NNE AT GYY. HAVE HIGH CONFIDENCE THAT THE LAKE BREEZE
WILL MAKE IT THROUGH MDW AND GYY AND MEDIUM-HIGH CONFIDENCE ABOUT
ORD. WINDS SLOWLY RETURN TO THE SW IN THE EVENING WITH CONTINUED
VFR CONDITIONS.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* HIGH CONFIDENCE IN LAKE BREEZE...MEDIUM CONFIDENCE IN
  TIMING...MEDIUM CONFIDENCE IN HOW FAR INLAND IT TRAVELS.

* MEDIUM-HIGH CONFIDENCE IN SHRA DEVELOPMENT AND COVERAGE...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY...SLIGHT CHANCE TSRA IN AFTN

FRIDAY...SLIGHT CHANCE TSRA IN AFTN

SATURDAY...CHANCE TSRA

SUNDAY...VFR

MONDAY...SLIGHT CHANCE TSRA

DANIELSON/RODRIGUEZ

&&

.MARINE...
210 PM CDT

HIGH PRESSURE IN THE NORTHERN AND CENTRAL PLAINS IS EXPECTED TO
WEAKEN SOME OVER THE COMING DAYS BUT GENERALLY REMAIN STATIONARY FOR
MOST OF THE WEEK AS AN UPPER LEVEL LOW PRESSURE SYSTEMS REMAINS
PARKED OVER JAMES BAY THROUGH SATURDAY. IN THIS PATTERN WEAK LOW
PRESSURE SYSTEMS WILL GLIDE SOUTHEAST DOWN THE LAKE AT TIMES...WITH
THE FIRST EXPECTED LATER TONIGHT INTO EARLY WEDNESDAY.

IN THIS STAGNANT PATTERN THE PRESSURE GRADIENT WILL REMAIN ON THE
LIGHTER SIDE AND WILL PROMOTE THE DEVELOPMENT OF LAKE BREEZES FOR
THE NEARSHORE WATERS AND VARIABLE WINDS OVER MUCH OF THE OPEN LAKE
AND WINDS GENERALLY 15 KT OR LESS.  KMD

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 300548
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1248 AM CDT WED JUL 30 2014

.DISCUSSION...
218 PM CDT

FORECAST ISSUES CONTINUE TO FOCUS ON DAILY DIURNAL ISOLATED TO
SCATTERED SHOWER/THUNDERSTORM CHANCES...WITH VERY GRADUAL WARM UP IN
TEMPERATURES THROUGH THE FORECAST PERIOD AS LONG WAVE UPPER TROUGH
OVER EASTERN NORTH AMERICA EFFECTIVELY RETROGRADES THROUGH THE END
OF THE WEEK BEFORE FINALLY WEAKENING AND PROGRESSING OFF TO THE
NORTHEAST BY LATE WEEKEND AND EARLY NEXT WEEK.

WESTERN GREAT LAKES REGION REMAINS IN WESTERN PERIPHERY OF THIS
AFOREMENTIONED TROUGH...WITHIN REGION OF BROAD CYCLONIC CIRCULATION.
SERIES OF RELATIVELY MINOR SHORT WAVES WILL CONTINUE TO RIPPLE
SOUTH-SOUTHEAST THROUGH THE FLOW ACROSS THE AREA THROUGH THE
REMAINDER OF THE WEEK. GOES WATER VAPOR IMAGERY INDICATES A COUPLE
OF WEAK RIPPLES PASSED ACROSS THE REGION THIS MORNING...WITH A
SOMEWHAT MORE ROBUST SHORT WAVE NOTED UPSTREAM PROPAGATING SOUTH
ACROSS WESTERN ONTARIO. THESE SYSTEMS WILL TEND TO MODULATE
MID-LEVEL TEMPS AND INSTABILITY...ESPECIALLY WHEN JUXTAPOSED ATOP
AFTERNOON/EARLY EVENING DIURNAL WARMTH. FORECAST SOUNDINGS CONTINUE
TO INDICATE WEAK/SKINNY MLCAPES OF 200-300 J/KG THIS AFTERNOON...
WITH VISIBLE SATELLITE IMAGERY INDICATING CUMULUS CONGESTUS
DEVELOPMENT ALONG WEAK LOW LEVEL CONVERGENCE AXIS FROM NEAR ROCKFORD
TO THE SOUTHEAST SIDE OF CHICAGO/NORTHWEST INDIANA WHERE THE LAKE
BREEZE BOUNDARY WAS PROVIDING SOME ADDITIONAL CONVERGENCE.
CURRENT WEAK RADAR RETURNS EXPECTED TO CONTINUE TO SLOWLY GROW
THIS AFTERNOON THROUGH PEAK INSTABILITY...RESULTING IN ISOLATED TO
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. WANING
INSTABILITY AFTER SUNSET THIS EVENING WILL ALLOW A DECREASE IN
COVERAGE. SIMILAR TREND EXPECTED TOMORROW...THOUGH ONTARIO SHORT
WAVE LOOKS TO MOVE ACROSS AREA DURING THE MORNING...AS OPPOSED TO
DURING PERIOD OF BETTER INSTABILITY LATER IN THE DAY. THIS MAY
FAVOR SOUTHEAST PARTS OF THE CWA WHERE FORCING WILL DECREASE
LAST...WHILE DAYTIME INSTABILITY DEVELOPS. THESE DIURNAL
SHOWERS/ISOLATED THUNDERSTORMS...TIED TO CONVERGENCE ZONES AS IS
THE CASE TODAY...WILL CONTINUE IN SIMILAR FASHION THURSDAY AS
WELL. OBVIOUSLY...NOT ALL AREAS WILL SEE PRECIP AND THERE WILL BE
MANY DRY HOURS EVEN IN PLACES THAT DO. BY FRIDAY...ADDITIONAL
SHORT WAVE ENERGY WILL DROP INTO THE WESTERN PORTION OF THE TROUGH
FROM THE NORTHERN PLAINS AND WILL EFFECTIVELY RETROGRADE THE LONG
WAVE TROUGH AXIS WESTWARD INTO THE WESTERN LAKES AND
MISSISSIPPI/LOWER OHIO VALLEY AREA. LARGE SCALE HEIGHT FALLS WILL
LEAD TO SLIGHTLY COOLER MID-LEVEL TEMPS WHICH MAY SUPPORT GREATER
COVERAGE IN SHOWERS/THUNDERSTORMS FRIDAY AND SATURDAY BEFORE THE
TROUGH AXIS BECOMES MORE PROGRESSIVE AND MOVES OFF TO THE EAST
SATURDAY NIGHT AND SUNDAY. THUS HAVE MAINTAINED SOMEWHAT HIGHER
CHANCE POPS WITH A GREATER AERIAL COVERAGE FOR THOSE DAYTIME
PERIODS.

SURFACE HIGH PRESSURE THEN BUILDS ACROSS THE AREA SUNDAY...BEFORE
DRIFTING TO THE SOUTHEAST MONDAY AS ANOTHER SHORT WAVE TROUGH
APPROACHES IN NORTHWEST FLOW ALOFT. THIS MID-LEVEL WAVE IS
ACCOMPANIED BY A SURFACE LOW AND COLD FRONT...WHICH RETURNS THE
SHOWER/THUNDERSTORM THREAT FOR MONDAY/TUESDAY OF NEXT WEEK.

AS FOR TEMPS...MID AND UPPER 70S BEING REACHED THIS AFTERNOON WITH
CONSIDERABLE SUNSHINE. MID-LEVEL TEMPS CONTINUE TO MODERATE VERY
SLOWLY THROUGH THE PERIOD...WITH TO SLOWLY WARMING FROM UPPER 70S TO
AROUND 80 TO LOWER 80S OUTSIDE OF LAKE BREEZE AND SHOWERS INTO THE
WEEKEND. COLD FRONTAL PASSAGE LATE MONDAY WILL ALLOW SUBTLE
COOL-DOWN FROM THE NORTH BY TUESDAY.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 06Z...

* LAKE BREEZE EXPECTED WITH NE WINDS AT 10 KT BEHIND IT.

* SCT SHRA THIS AFTN AND EVENING. A FEW TSRA PSBL.

JEE

//DISCUSSION...UPDATED 06Z...

SHOWERS HAVE PUSHED SOUTH OF THE TERMINALS BUT TODAY IS LOOKING
VERY SIMILAR TO YESTERDAY. A LAKE BREEZE IS EXPECTED ALONG WITH A
WEAKER UPPER LEVEL WAVE. THE LAKE BREEZE WILL PROVIDE ENOUGH
FORCING FOR SCT SHRA THIS AFTN AND EVENING...BUT THINKING WE WILL
SEE LESS ACTIVITY THAN YESTERDAY. A FEW THUNDERSTORMS ARE ALSO
EXPECTED AS WELL BUT THEY SHOULD BE ISOLATED ENOUGH TO LEAVE OUT
OF THE TAF FOR NOW.

WINDS BECOME NE ARND 10 KT BEHIND THE LAKE BREEZE AT MDW AND
ORD....AND NNE AT GYY. HAVE HIGH CONFIDENCE THAT THE LAKE BREEZE
WILL MAKE IT THROUGH MDW AND GYY AND MEDIUM-HIGH CONFIDENCE ABOUT
ORD. WINDS SLOWLY RETURN TO THE SW IN THE EVENING WITH CONTINUED
VFR CONDITIONS.

JEE


//ORD AND MDW CONFIDENCE...UPDATED 06Z...

* HIGH CONFIDENCE IN LAKE BREEZE...MEDIUM CONFIDENCE IN
  TIMING...MEDIUM CONFIDENCE IN HOW FAR INLAND IT TRAVELS.

* MEDIUM-HIGH CONFIDENCE IN SHRA DEVELOPMENT AND COVERAGE...LOW
  CONFIDENCE IN TSRA COVERAGE AND DEVELOPMENT.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY...SLIGHT CHANCE TSRA IN AFTN

FRIDAY...SLIGHT CHANCE TSRA IN AFTN

SATURDAY...CHANCE TSRA

SUNDAY...VFR

MONDAY...SLIGHT CHANCE TSRA

DANIELSON/RODRIGUEZ

&&

.MARINE...
210 PM CDT

HIGH PRESSURE IN THE NORTHERN AND CENTRAL PLAINS IS EXPECTED TO
WEAKEN SOME OVER THE COMING DAYS BUT GENERALLY REMAIN STATIONARY FOR
MOST OF THE WEEK AS AN UPPER LEVEL LOW PRESSURE SYSTEMS REMAINS
PARKED OVER JAMES BAY THROUGH SATURDAY. IN THIS PATTERN WEAK LOW
PRESSURE SYSTEMS WILL GLIDE SOUTHEAST DOWN THE LAKE AT TIMES...WITH
THE FIRST EXPECTED LATER TONIGHT INTO EARLY WEDNESDAY.

IN THIS STAGNANT PATTERN THE PRESSURE GRADIENT WILL REMAIN ON THE
LIGHTER SIDE AND WILL PROMOTE THE DEVELOPMENT OF LAKE BREEZES FOR
THE NEARSHORE WATERS AND VARIABLE WINDS OVER MUCH OF THE OPEN LAKE
AND WINDS GENERALLY 15 KT OR LESS.  KMD

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KILX 300455
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1155 PM CDT Tue Jul 29 2014

.DISCUSSION...
ISSUED 856 PM CDT Tue Jul 29 2014

Skies are mostly clear and winds have become light. Expect these
conditions to continue overnight and into the early morning hours.
Current forecast has a good handle on this, so no update needed tonight.



&&

.AVIATION...
ISSUED 1155 PM CDT Tue Jul 29 2014

Clear skies and light winds will continue overnight. VFR conditions
will continue at all TAF sites next 24hrs. A line of scattered showers
continues to move southeast through northeast IL tonight. Though
it looks like they could reach toward Champaignving they should
miss the TAF site overnight. Will not have any pcpn mentioned
at CMI at this time. Winds tomorrow will be westerly at around
10kts with scattered CU around 5kft and then dissipate again
tomorrow evening with lighter winds.

Auten
&&

.PREV DISCUSSION...
ISSUED 230 PM CDT Tue Jul 29 2014

Latest radar mosaics showing isolated showers and thunderstorms
from near Rockford southeast into central Indiana, along a weak
convergence boundary. HRRR suggests some of this may clip the far
northeast CWA later this afternoon, where 20% PoP`s remain in
place. Am planning on leaving the evening dry, as any lingering
showers will quickly be fizzling as sunset approaches.

Upper air analysis continues to show strong ridging west of the
Rockies northward into Canada, with the eastern states and
provinces dominated by a broad long wave trough anchored via an
upper low spinning north of the Great Lakes. The long range
pattern does not change during the forecast period, except that
the upper low opens up some and starts to lift northeast. Some
hints exist that it may return early next week, but the associated
cooler surge looks to stay north of Illinois at this point.

Little change in the going forecast is needed. Temperatures are
expected to rise a couple degrees, with lower 80s for highs and
upper 50s-lower 60s for lows from Wednesday through the weekend,
and slightly warmer early next week. Precipitation chances remain
focused on Friday and Saturday, mainly diurnally driven, as weak
shortwaves pivot through in the broader upper troughs.

Geelhart


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KILX 300455
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1155 PM CDT Tue Jul 29 2014

.DISCUSSION...
ISSUED 856 PM CDT Tue Jul 29 2014

Skies are mostly clear and winds have become light. Expect these
conditions to continue overnight and into the early morning hours.
Current forecast has a good handle on this, so no update needed tonight.



&&

.AVIATION...
ISSUED 1155 PM CDT Tue Jul 29 2014

Clear skies and light winds will continue overnight. VFR conditions
will continue at all TAF sites next 24hrs. A line of scattered showers
continues to move southeast through northeast IL tonight. Though
it looks like they could reach toward Champaignving they should
miss the TAF site overnight. Will not have any pcpn mentioned
at CMI at this time. Winds tomorrow will be westerly at around
10kts with scattered CU around 5kft and then dissipate again
tomorrow evening with lighter winds.

Auten
&&

.PREV DISCUSSION...
ISSUED 230 PM CDT Tue Jul 29 2014

Latest radar mosaics showing isolated showers and thunderstorms
from near Rockford southeast into central Indiana, along a weak
convergence boundary. HRRR suggests some of this may clip the far
northeast CWA later this afternoon, where 20% PoP`s remain in
place. Am planning on leaving the evening dry, as any lingering
showers will quickly be fizzling as sunset approaches.

Upper air analysis continues to show strong ridging west of the
Rockies northward into Canada, with the eastern states and
provinces dominated by a broad long wave trough anchored via an
upper low spinning north of the Great Lakes. The long range
pattern does not change during the forecast period, except that
the upper low opens up some and starts to lift northeast. Some
hints exist that it may return early next week, but the associated
cooler surge looks to stay north of Illinois at this point.

Little change in the going forecast is needed. Temperatures are
expected to rise a couple degrees, with lower 80s for highs and
upper 50s-lower 60s for lows from Wednesday through the weekend,
and slightly warmer early next week. Precipitation chances remain
focused on Friday and Saturday, mainly diurnally driven, as weak
shortwaves pivot through in the broader upper troughs.

Geelhart


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KILX 300455
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1155 PM CDT Tue Jul 29 2014

.DISCUSSION...
ISSUED 856 PM CDT Tue Jul 29 2014

Skies are mostly clear and winds have become light. Expect these
conditions to continue overnight and into the early morning hours.
Current forecast has a good handle on this, so no update needed tonight.



&&

.AVIATION...
ISSUED 1155 PM CDT Tue Jul 29 2014

Clear skies and light winds will continue overnight. VFR conditions
will continue at all TAF sites next 24hrs. A line of scattered showers
continues to move southeast through northeast IL tonight. Though
it looks like they could reach toward Champaignving they should
miss the TAF site overnight. Will not have any pcpn mentioned
at CMI at this time. Winds tomorrow will be westerly at around
10kts with scattered CU around 5kft and then dissipate again
tomorrow evening with lighter winds.

Auten
&&

.PREV DISCUSSION...
ISSUED 230 PM CDT Tue Jul 29 2014

Latest radar mosaics showing isolated showers and thunderstorms
from near Rockford southeast into central Indiana, along a weak
convergence boundary. HRRR suggests some of this may clip the far
northeast CWA later this afternoon, where 20% PoP`s remain in
place. Am planning on leaving the evening dry, as any lingering
showers will quickly be fizzling as sunset approaches.

Upper air analysis continues to show strong ridging west of the
Rockies northward into Canada, with the eastern states and
provinces dominated by a broad long wave trough anchored via an
upper low spinning north of the Great Lakes. The long range
pattern does not change during the forecast period, except that
the upper low opens up some and starts to lift northeast. Some
hints exist that it may return early next week, but the associated
cooler surge looks to stay north of Illinois at this point.

Little change in the going forecast is needed. Temperatures are
expected to rise a couple degrees, with lower 80s for highs and
upper 50s-lower 60s for lows from Wednesday through the weekend,
and slightly warmer early next week. Precipitation chances remain
focused on Friday and Saturday, mainly diurnally driven, as weak
shortwaves pivot through in the broader upper troughs.

Geelhart


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KILX 300455
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1155 PM CDT Tue Jul 29 2014

.DISCUSSION...
ISSUED 856 PM CDT Tue Jul 29 2014

Skies are mostly clear and winds have become light. Expect these
conditions to continue overnight and into the early morning hours.
Current forecast has a good handle on this, so no update needed tonight.



&&

.AVIATION...
ISSUED 1155 PM CDT Tue Jul 29 2014

Clear skies and light winds will continue overnight. VFR conditions
will continue at all TAF sites next 24hrs. A line of scattered showers
continues to move southeast through northeast IL tonight. Though
it looks like they could reach toward Champaignving they should
miss the TAF site overnight. Will not have any pcpn mentioned
at CMI at this time. Winds tomorrow will be westerly at around
10kts with scattered CU around 5kft and then dissipate again
tomorrow evening with lighter winds.

Auten
&&

.PREV DISCUSSION...
ISSUED 230 PM CDT Tue Jul 29 2014

Latest radar mosaics showing isolated showers and thunderstorms
from near Rockford southeast into central Indiana, along a weak
convergence boundary. HRRR suggests some of this may clip the far
northeast CWA later this afternoon, where 20% PoP`s remain in
place. Am planning on leaving the evening dry, as any lingering
showers will quickly be fizzling as sunset approaches.

Upper air analysis continues to show strong ridging west of the
Rockies northward into Canada, with the eastern states and
provinces dominated by a broad long wave trough anchored via an
upper low spinning north of the Great Lakes. The long range
pattern does not change during the forecast period, except that
the upper low opens up some and starts to lift northeast. Some
hints exist that it may return early next week, but the associated
cooler surge looks to stay north of Illinois at this point.

Little change in the going forecast is needed. Temperatures are
expected to rise a couple degrees, with lower 80s for highs and
upper 50s-lower 60s for lows from Wednesday through the weekend,
and slightly warmer early next week. Precipitation chances remain
focused on Friday and Saturday, mainly diurnally driven, as weak
shortwaves pivot through in the broader upper troughs.

Geelhart


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 300400
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1100 PM CDT TUE JUL 29 2014

.DISCUSSION...
218 PM CDT

FORECAST ISSUES CONTINUE TO FOCUS ON DAILY DIURNAL ISOLATED TO
SCATTERED SHOWER/THUNDERSTORM CHANCES...WITH VERY GRADUAL WARM UP IN
TEMPERATURES THROUGH THE FORECAST PERIOD AS LONG WAVE UPPER TROUGH
OVER EASTERN NORTH AMERICA EFFECTIVELY RETROGRADES THROUGH THE END
OF THE WEEK BEFORE FINALLY WEAKENING AND PROGRESSING OFF TO THE
NORTHEAST BY LATE WEEKEND AND EARLY NEXT WEEK.

WESTERN GREAT LAKES REGION REMAINS IN WESTERN PERIPHERY OF THIS
AFOREMENTIONED TROUGH...WITHIN REGION OF BROAD CYCLONIC CIRCULATION.
SERIES OF RELATIVELY MINOR SHORT WAVES WILL CONTINUE TO RIPPLE
SOUTH-SOUTHEAST THROUGH THE FLOW ACROSS THE AREA THROUGH THE
REMAINDER OF THE WEEK. GOES WATER VAPOR IMAGERY INDICATES A COUPLE
OF WEAK RIPPLES PASSED ACROSS THE REGION THIS MORNING...WITH A
SOMEWHAT MORE ROBUST SHORT WAVE NOTED UPSTREAM PROPAGATING SOUTH
ACROSS WESTERN ONTARIO. THESE SYSTEMS WILL TEND TO MODULATE
MID-LEVEL TEMPS AND INSTABILITY...ESPECIALLY WHEN JUXTAPOSED ATOP
AFTERNOON/EARLY EVENING DIURNAL WARMTH. FORECAST SOUNDINGS CONTINUE
TO INDICATE WEAK/SKINNY MLCAPES OF 200-300 J/KG THIS AFTERNOON...
WITH VISIBLE SATELLITE IMAGERY INDICATING CUMULUS CONGESTUS
DEVELOPMENT ALONG WEAK LOW LEVEL CONVERGENCE AXIS FROM NEAR ROCKFORD
TO THE SOUTHEAST SIDE OF CHICAGO/NORTHWEST INDIANA WHERE THE LAKE
BREEZE BOUNDARY WAS PROVIDING SOME ADDITIONAL CONVERGENCE.
CURRENT WEAK RADAR RETURNS EXPECTED TO CONTINUE TO SLOWLY GROW
THIS AFTERNOON THROUGH PEAK INSTABILITY...RESULTING IN ISOLATED TO
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. WANING
INSTABILITY AFTER SUNSET THIS EVENING WILL ALLOW A DECREASE IN
COVERAGE. SIMILAR TREND EXPECTED TOMORROW...THOUGH ONTARIO SHORT
WAVE LOOKS TO MOVE ACROSS AREA DURING THE MORNING...AS OPPOSED TO
DURING PERIOD OF BETTER INSTABILITY LATER IN THE DAY. THIS MAY
FAVOR SOUTHEAST PARTS OF THE CWA WHERE FORCING WILL DECREASE
LAST...WHILE DAYTIME INSTABILITY DEVELOPS. THESE DIURNAL
SHOWERS/ISOLATED THUNDERSTORMS...TIED TO CONVERGENCE ZONES AS IS
THE CASE TODAY...WILL CONTINUE IN SIMILAR FASHION THURSDAY AS
WELL. OBVIOUSLY...NOT ALL AREAS WILL SEE PRECIP AND THERE WILL BE
MANY DRY HOURS EVEN IN PLACES THAT DO. BY FRIDAY...ADDITIONAL
SHORT WAVE ENERGY WILL DROP INTO THE WESTERN PORTION OF THE TROUGH
FROM THE NORTHERN PLAINS AND WILL EFFECTIVELY RETROGRADE THE LONG
WAVE TROUGH AXIS WESTWARD INTO THE WESTERN LAKES AND
MISSISSIPPI/LOWER OHIO VALLEY AREA. LARGE SCALE HEIGHT FALLS WILL
LEAD TO SLIGHTLY COOLER MID-LEVEL TEMPS WHICH MAY SUPPORT GREATER
COVERAGE IN SHOWERS/THUNDERSTORMS FRIDAY AND SATURDAY BEFORE THE
TROUGH AXIS BECOMES MORE PROGRESSIVE AND MOVES OFF TO THE EAST
SATURDAY NIGHT AND SUNDAY. THUS HAVE MAINTAINED SOMEWHAT HIGHER
CHANCE POPS WITH A GREATER AERIAL COVERAGE FOR THOSE DAYTIME
PERIODS.

SURFACE HIGH PRESSURE THEN BUILDS ACROSS THE AREA SUNDAY...BEFORE
DRIFTING TO THE SOUTHEAST MONDAY AS ANOTHER SHORT WAVE TROUGH
APPROACHES IN NORTHWEST FLOW ALOFT. THIS MID-LEVEL WAVE IS
ACCOMPANIED BY A SURFACE LOW AND COLD FRONT...WHICH RETURNS THE
SHOWER/THUNDERSTORM THREAT FOR MONDAY/TUESDAY OF NEXT WEEK.

AS FOR TEMPS...MID AND UPPER 70S BEING REACHED THIS AFTERNOON WITH
CONSIDERABLE SUNSHINE. MID-LEVEL TEMPS CONTINUE TO MODERATE VERY
SLOWLY THROUGH THE PERIOD...WITH TO SLOWLY WARMING FROM UPPER 70S TO
AROUND 80 TO LOWER 80S OUTSIDE OF LAKE BREEZE AND SHOWERS INTO THE
WEEKEND. COLD FRONTAL PASSAGE LATE MONDAY WILL ALLOW SUBTLE
COOL-DOWN FROM THE NORTH BY TUESDAY.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* SHRA PUSHING THROUGH LATE THIS EVENING WITH CURRENT NORTHERLY
  WINDS DIMINISHING AND BECOMING MORE WEST NORTHWEST WITHIN THE
  NEXT 1-2 HOURS.

* LAKE BREEZE LIKELY FOR MDW WEDNESDAY AFTN WITH NE/E WINDS. LAKE
  BREEZE QUESTIONABLE FOR ORD.

* ISOL TO SCT SHRA TO FORM WEDNESDAY EARLY AFTN AND PERSIST
  THROUGH THE AFTN INTO THE EVENING.

DANIELSON/RODRIGUEZ

//DISCUSSION...UPDATED 00Z...

CONVECTIVELY INDUCED OUTFLOW BOUNDARY HAS MERGED WITH LAKE BREEZE
AND PUSHED EASTWARD. WINDS AT ORD AND MDW HAVE SHIFTED TO WEST AT
10 KTS. SOME LINGERING SHRA NEAR ROCKFORD AND YORKVILLE HAVE
PERSISTED BUT WITH INSTABILITY DECREASING AS THE SUN SETS THESE
WILL DISSIPATE MUCH LIKE THE REST OF THE SHRA ACTIVITY HAS IN THE
PAST HOUR. CONCERNS THEN TURN TO SHRA IN WISCONSIN WITH BETTER
COVERAGE THAN STORMS IN OUR AREA. THESE STORMS HAVE PERSISTED ON A
DECENT SURFACE TROUGH AXIS AND WEAK UPPER LEVEL SUPPORT. THIS
ACTIVITY SHOULD BEGIN TO DIMINISH BUT WILL WATCH THESE AS THEY
APPROACH THE WISCONSIN ILLINOIS BORDER. HAVE INDICATED VCSH AT RFD
FROM 02Z TO 04Z DUE TO THIS ACTIVITY.

FOCUS THEN TURNS TO SHRA ACTIVITY WEDNESDAY AND LAKE BREEZE.
CONDITIONS WILL BE SIMILAR TO TODAY WITH WEST-NORTHWEST WINDS
INCREASING IN THE MORNING HOURS. STEEP LOW LEVEL LAPSE RATES AND A
WEAK SHORTWAVE WILL PROVIDE LIFT FOR SHRA FORMING AROUND 2PM AND
LINGERING INTO THE AFTERNOON AND EARLY EVENING. HAVE INDICATED
VCSH AT 19Z FOR ALL AIRPORTS. LOW CONFIDENCE IN ANY TSRA
DEVELOPING BUT COVERAGE WILL BE MINIMAL IF IT DOES OCCUR.
INTENSITY OF THE SHRA AND WEST WINDS WILL NEED TO BE MONITORED TO
GET A BETTER GRASP ON THE LAKE BREEZE WEDNESDAY AFTN. WILL LIKELY
SEE LAKE BREEZE PUSH THROUGH GYY AND MDW. AS ELUDED TO BEFORE
CONDITIONS WILL NEED TO BE WATCHED TO SEE IF LAKE BREEZE WILL PUSH
THROUGH ORD. LAKE BREEZE UNLIKELY AT DPA. SHRA DIMINISHES
WEDNESDAY EVENING AND WINDS WEAKEN AS SUN SETS.

DANIELSON/RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* HIGH CONFIDENCE WITH SHRA TRENDS LATE THIS EVENING...MEDIUM
  CONFIDENCE WITH OVERALL TRENDS WITH WIND DIRECTION/SPEED LATE
  THIS EVENING.

* LOW CONFIDENCE FOR TIMING OF LAKE BREEZE REACHING ORD AND MDW.

* MEDIUM TO HIGH CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE
  AREA WEDNESDAY AFTERNOON. LOW CONFIDENCE IN TSRA DEVELOPMENT.

DANIELSON/RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY...SLIGHT CHANCE TSRA IN AFTN

FRIDAY...SLIGHT CHANCE TSRA IN AFTN

SATURDAY...CHANCE TSRA

SUNDAY...VFR

MONDAY...SLIGHT CHANCE TSRA

DANIELSON/RODRIGUEZ

&&

.MARINE...
210 PM CDT

HIGH PRESSURE IN THE NORTHERN AND CENTRAL PLAINS IS EXPECTED TO
WEAKEN SOME OVER THE COMING DAYS BUT GENERALLY REMAIN STATIONARY FOR
MOST OF THE WEEK AS AN UPPER LEVEL LOW PRESSURE SYSTEMS REMAINS
PARKED OVER JAMES BAY THROUGH SATURDAY. IN THIS PATTERN WEAK LOW
PRESSURE SYSTEMS WILL GLIDE SOUTHEAST DOWN THE LAKE AT TIMES...WITH
THE FIRST EXPECTED LATER TONIGHT INTO EARLY WEDNESDAY.

IN THIS STAGNANT PATTERN THE PRESSURE GRADIENT WILL REMAIN ON THE
LIGHTER SIDE AND WILL PROMOTE THE DEVELOPMENT OF LAKE BREEZES FOR
THE NEARSHORE WATERS AND VARIABLE WINDS OVER MUCH OF THE OPEN LAKE
AND WINDS GENERALLY 15 KT OR LESS.  KMD

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 300400
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1100 PM CDT TUE JUL 29 2014

.DISCUSSION...
218 PM CDT

FORECAST ISSUES CONTINUE TO FOCUS ON DAILY DIURNAL ISOLATED TO
SCATTERED SHOWER/THUNDERSTORM CHANCES...WITH VERY GRADUAL WARM UP IN
TEMPERATURES THROUGH THE FORECAST PERIOD AS LONG WAVE UPPER TROUGH
OVER EASTERN NORTH AMERICA EFFECTIVELY RETROGRADES THROUGH THE END
OF THE WEEK BEFORE FINALLY WEAKENING AND PROGRESSING OFF TO THE
NORTHEAST BY LATE WEEKEND AND EARLY NEXT WEEK.

WESTERN GREAT LAKES REGION REMAINS IN WESTERN PERIPHERY OF THIS
AFOREMENTIONED TROUGH...WITHIN REGION OF BROAD CYCLONIC CIRCULATION.
SERIES OF RELATIVELY MINOR SHORT WAVES WILL CONTINUE TO RIPPLE
SOUTH-SOUTHEAST THROUGH THE FLOW ACROSS THE AREA THROUGH THE
REMAINDER OF THE WEEK. GOES WATER VAPOR IMAGERY INDICATES A COUPLE
OF WEAK RIPPLES PASSED ACROSS THE REGION THIS MORNING...WITH A
SOMEWHAT MORE ROBUST SHORT WAVE NOTED UPSTREAM PROPAGATING SOUTH
ACROSS WESTERN ONTARIO. THESE SYSTEMS WILL TEND TO MODULATE
MID-LEVEL TEMPS AND INSTABILITY...ESPECIALLY WHEN JUXTAPOSED ATOP
AFTERNOON/EARLY EVENING DIURNAL WARMTH. FORECAST SOUNDINGS CONTINUE
TO INDICATE WEAK/SKINNY MLCAPES OF 200-300 J/KG THIS AFTERNOON...
WITH VISIBLE SATELLITE IMAGERY INDICATING CUMULUS CONGESTUS
DEVELOPMENT ALONG WEAK LOW LEVEL CONVERGENCE AXIS FROM NEAR ROCKFORD
TO THE SOUTHEAST SIDE OF CHICAGO/NORTHWEST INDIANA WHERE THE LAKE
BREEZE BOUNDARY WAS PROVIDING SOME ADDITIONAL CONVERGENCE.
CURRENT WEAK RADAR RETURNS EXPECTED TO CONTINUE TO SLOWLY GROW
THIS AFTERNOON THROUGH PEAK INSTABILITY...RESULTING IN ISOLATED TO
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. WANING
INSTABILITY AFTER SUNSET THIS EVENING WILL ALLOW A DECREASE IN
COVERAGE. SIMILAR TREND EXPECTED TOMORROW...THOUGH ONTARIO SHORT
WAVE LOOKS TO MOVE ACROSS AREA DURING THE MORNING...AS OPPOSED TO
DURING PERIOD OF BETTER INSTABILITY LATER IN THE DAY. THIS MAY
FAVOR SOUTHEAST PARTS OF THE CWA WHERE FORCING WILL DECREASE
LAST...WHILE DAYTIME INSTABILITY DEVELOPS. THESE DIURNAL
SHOWERS/ISOLATED THUNDERSTORMS...TIED TO CONVERGENCE ZONES AS IS
THE CASE TODAY...WILL CONTINUE IN SIMILAR FASHION THURSDAY AS
WELL. OBVIOUSLY...NOT ALL AREAS WILL SEE PRECIP AND THERE WILL BE
MANY DRY HOURS EVEN IN PLACES THAT DO. BY FRIDAY...ADDITIONAL
SHORT WAVE ENERGY WILL DROP INTO THE WESTERN PORTION OF THE TROUGH
FROM THE NORTHERN PLAINS AND WILL EFFECTIVELY RETROGRADE THE LONG
WAVE TROUGH AXIS WESTWARD INTO THE WESTERN LAKES AND
MISSISSIPPI/LOWER OHIO VALLEY AREA. LARGE SCALE HEIGHT FALLS WILL
LEAD TO SLIGHTLY COOLER MID-LEVEL TEMPS WHICH MAY SUPPORT GREATER
COVERAGE IN SHOWERS/THUNDERSTORMS FRIDAY AND SATURDAY BEFORE THE
TROUGH AXIS BECOMES MORE PROGRESSIVE AND MOVES OFF TO THE EAST
SATURDAY NIGHT AND SUNDAY. THUS HAVE MAINTAINED SOMEWHAT HIGHER
CHANCE POPS WITH A GREATER AERIAL COVERAGE FOR THOSE DAYTIME
PERIODS.

SURFACE HIGH PRESSURE THEN BUILDS ACROSS THE AREA SUNDAY...BEFORE
DRIFTING TO THE SOUTHEAST MONDAY AS ANOTHER SHORT WAVE TROUGH
APPROACHES IN NORTHWEST FLOW ALOFT. THIS MID-LEVEL WAVE IS
ACCOMPANIED BY A SURFACE LOW AND COLD FRONT...WHICH RETURNS THE
SHOWER/THUNDERSTORM THREAT FOR MONDAY/TUESDAY OF NEXT WEEK.

AS FOR TEMPS...MID AND UPPER 70S BEING REACHED THIS AFTERNOON WITH
CONSIDERABLE SUNSHINE. MID-LEVEL TEMPS CONTINUE TO MODERATE VERY
SLOWLY THROUGH THE PERIOD...WITH TO SLOWLY WARMING FROM UPPER 70S TO
AROUND 80 TO LOWER 80S OUTSIDE OF LAKE BREEZE AND SHOWERS INTO THE
WEEKEND. COLD FRONTAL PASSAGE LATE MONDAY WILL ALLOW SUBTLE
COOL-DOWN FROM THE NORTH BY TUESDAY.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* SHRA PUSHING THROUGH LATE THIS EVENING WITH CURRENT NORTHERLY
  WINDS DIMINISHING AND BECOMING MORE WEST NORTHWEST WITHIN THE
  NEXT 1-2 HOURS.

* LAKE BREEZE LIKELY FOR MDW WEDNESDAY AFTN WITH NE/E WINDS. LAKE
  BREEZE QUESTIONABLE FOR ORD.

* ISOL TO SCT SHRA TO FORM WEDNESDAY EARLY AFTN AND PERSIST
  THROUGH THE AFTN INTO THE EVENING.

DANIELSON/RODRIGUEZ

//DISCUSSION...UPDATED 00Z...

CONVECTIVELY INDUCED OUTFLOW BOUNDARY HAS MERGED WITH LAKE BREEZE
AND PUSHED EASTWARD. WINDS AT ORD AND MDW HAVE SHIFTED TO WEST AT
10 KTS. SOME LINGERING SHRA NEAR ROCKFORD AND YORKVILLE HAVE
PERSISTED BUT WITH INSTABILITY DECREASING AS THE SUN SETS THESE
WILL DISSIPATE MUCH LIKE THE REST OF THE SHRA ACTIVITY HAS IN THE
PAST HOUR. CONCERNS THEN TURN TO SHRA IN WISCONSIN WITH BETTER
COVERAGE THAN STORMS IN OUR AREA. THESE STORMS HAVE PERSISTED ON A
DECENT SURFACE TROUGH AXIS AND WEAK UPPER LEVEL SUPPORT. THIS
ACTIVITY SHOULD BEGIN TO DIMINISH BUT WILL WATCH THESE AS THEY
APPROACH THE WISCONSIN ILLINOIS BORDER. HAVE INDICATED VCSH AT RFD
FROM 02Z TO 04Z DUE TO THIS ACTIVITY.

FOCUS THEN TURNS TO SHRA ACTIVITY WEDNESDAY AND LAKE BREEZE.
CONDITIONS WILL BE SIMILAR TO TODAY WITH WEST-NORTHWEST WINDS
INCREASING IN THE MORNING HOURS. STEEP LOW LEVEL LAPSE RATES AND A
WEAK SHORTWAVE WILL PROVIDE LIFT FOR SHRA FORMING AROUND 2PM AND
LINGERING INTO THE AFTERNOON AND EARLY EVENING. HAVE INDICATED
VCSH AT 19Z FOR ALL AIRPORTS. LOW CONFIDENCE IN ANY TSRA
DEVELOPING BUT COVERAGE WILL BE MINIMAL IF IT DOES OCCUR.
INTENSITY OF THE SHRA AND WEST WINDS WILL NEED TO BE MONITORED TO
GET A BETTER GRASP ON THE LAKE BREEZE WEDNESDAY AFTN. WILL LIKELY
SEE LAKE BREEZE PUSH THROUGH GYY AND MDW. AS ELUDED TO BEFORE
CONDITIONS WILL NEED TO BE WATCHED TO SEE IF LAKE BREEZE WILL PUSH
THROUGH ORD. LAKE BREEZE UNLIKELY AT DPA. SHRA DIMINISHES
WEDNESDAY EVENING AND WINDS WEAKEN AS SUN SETS.

DANIELSON/RODRIGUEZ

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* HIGH CONFIDENCE WITH SHRA TRENDS LATE THIS EVENING...MEDIUM
  CONFIDENCE WITH OVERALL TRENDS WITH WIND DIRECTION/SPEED LATE
  THIS EVENING.

* LOW CONFIDENCE FOR TIMING OF LAKE BREEZE REACHING ORD AND MDW.

* MEDIUM TO HIGH CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE
  AREA WEDNESDAY AFTERNOON. LOW CONFIDENCE IN TSRA DEVELOPMENT.

DANIELSON/RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY...SLIGHT CHANCE TSRA IN AFTN

FRIDAY...SLIGHT CHANCE TSRA IN AFTN

SATURDAY...CHANCE TSRA

SUNDAY...VFR

MONDAY...SLIGHT CHANCE TSRA

DANIELSON/RODRIGUEZ

&&

.MARINE...
210 PM CDT

HIGH PRESSURE IN THE NORTHERN AND CENTRAL PLAINS IS EXPECTED TO
WEAKEN SOME OVER THE COMING DAYS BUT GENERALLY REMAIN STATIONARY FOR
MOST OF THE WEEK AS AN UPPER LEVEL LOW PRESSURE SYSTEMS REMAINS
PARKED OVER JAMES BAY THROUGH SATURDAY. IN THIS PATTERN WEAK LOW
PRESSURE SYSTEMS WILL GLIDE SOUTHEAST DOWN THE LAKE AT TIMES...WITH
THE FIRST EXPECTED LATER TONIGHT INTO EARLY WEDNESDAY.

IN THIS STAGNANT PATTERN THE PRESSURE GRADIENT WILL REMAIN ON THE
LIGHTER SIDE AND WILL PROMOTE THE DEVELOPMENT OF LAKE BREEZES FOR
THE NEARSHORE WATERS AND VARIABLE WINDS OVER MUCH OF THE OPEN LAKE
AND WINDS GENERALLY 15 KT OR LESS.  KMD

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KILX 300156
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
856 PM CDT Tue Jul 29 2014

.DISCUSSION...
ISSUED 856 PM CDT Tue Jul 29 2014

Skies are mostly clear and winds have become light. Expect these
conditions to continue overnight and into the early morning hours.
Current forecast has a good handle on this, so no update needed tonight.

Auten
&&

.AVIATION...
ISSUED 624 PM CDT Tue Jul 29 2014

Skies will quickly clear this evening and winds will become light
out of the west. These VFR conditions will continue at all TAF
sites next 24hrs. A line of showers and isolated thunderstorms was
dropping south through northeast IL late this afternoon. This
could reach areas north of Champaign, but looks like it is moving
slightly east of south and should miss the TAF site this evening.
Will not have any pcpn mentioned at CMI but will continue to
monitor trends and see if VCSH is needed at some point. Pcpn
should also be dissipating as it moves south. Winds tomorrow will
be westerly at around 10kts with scattered CU around 5kft.

Auten
&&

.PREV DISCUSSION...
ISSUED 230 PM CDT Tue Jul 29 2014

Latest radar mosaics showing isolated showers and thunderstorms
from near Rockford southeast into central Indiana, along a weak
convergence boundary. HRRR suggests some of this may clip the far
northeast CWA later this afternoon, where 20% PoP`s remain in
place. Am planning on leaving the evening dry, as any lingering
showers will quickly be fizzling as sunset approaches.

Upper air analysis continues to show strong ridging west of the
Rockies northward into Canada, with the eastern states and
provinces dominated by a broad long wave trough anchored via an
upper low spinning north of the Great Lakes. The long range
pattern does not change during the forecast period, except that
the upper low opens up some and starts to lift northeast. Some
hints exist that it may return early next week, but the associated
cooler surge looks to stay north of Illinois at this point.

Little change in the going forecast is needed. Temperatures are
expected to rise a couple degrees, with lower 80s for highs and
upper 50s-lower 60s for lows from Wednesday through the weekend,
and slightly warmer early next week. Precipitation chances remain
focused on Friday and Saturday, mainly diurnally driven, as weak
shortwaves pivot through in the broader upper troughs.

Geelhart

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KILX 300156
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
856 PM CDT Tue Jul 29 2014

.DISCUSSION...
ISSUED 856 PM CDT Tue Jul 29 2014

Skies are mostly clear and winds have become light. Expect these
conditions to continue overnight and into the early morning hours.
Current forecast has a good handle on this, so no update needed tonight.

Auten
&&

.AVIATION...
ISSUED 624 PM CDT Tue Jul 29 2014

Skies will quickly clear this evening and winds will become light
out of the west. These VFR conditions will continue at all TAF
sites next 24hrs. A line of showers and isolated thunderstorms was
dropping south through northeast IL late this afternoon. This
could reach areas north of Champaign, but looks like it is moving
slightly east of south and should miss the TAF site this evening.
Will not have any pcpn mentioned at CMI but will continue to
monitor trends and see if VCSH is needed at some point. Pcpn
should also be dissipating as it moves south. Winds tomorrow will
be westerly at around 10kts with scattered CU around 5kft.

Auten
&&

.PREV DISCUSSION...
ISSUED 230 PM CDT Tue Jul 29 2014

Latest radar mosaics showing isolated showers and thunderstorms
from near Rockford southeast into central Indiana, along a weak
convergence boundary. HRRR suggests some of this may clip the far
northeast CWA later this afternoon, where 20% PoP`s remain in
place. Am planning on leaving the evening dry, as any lingering
showers will quickly be fizzling as sunset approaches.

Upper air analysis continues to show strong ridging west of the
Rockies northward into Canada, with the eastern states and
provinces dominated by a broad long wave trough anchored via an
upper low spinning north of the Great Lakes. The long range
pattern does not change during the forecast period, except that
the upper low opens up some and starts to lift northeast. Some
hints exist that it may return early next week, but the associated
cooler surge looks to stay north of Illinois at this point.

Little change in the going forecast is needed. Temperatures are
expected to rise a couple degrees, with lower 80s for highs and
upper 50s-lower 60s for lows from Wednesday through the weekend,
and slightly warmer early next week. Precipitation chances remain
focused on Friday and Saturday, mainly diurnally driven, as weak
shortwaves pivot through in the broader upper troughs.

Geelhart

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$







000
FXUS63 KLOT 300016
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
716 PM CDT TUE JUL 29 2014

.DISCUSSION...
218 PM CDT

FORECAST ISSUES CONTINUE TO FOCUS ON DAILY DIURNAL ISOLATED TO
SCATTERED SHOWER/THUNDERSTORM CHANCES...WITH VERY GRADUAL WARM UP IN
TEMPERATURES THROUGH THE FORECAST PERIOD AS LONG WAVE UPPER TROUGH
OVER EASTERN NORTH AMERICA EFFECTIVELY RETROGRADES THROUGH THE END
OF THE WEEK BEFORE FINALLY WEAKENING AND PROGRESSING OFF TO THE
NORTHEAST BY LATE WEEKEND AND EARLY NEXT WEEK.

WESTERN GREAT LAKES REGION REMAINS IN WESTERN PERIPHERY OF THIS
AFOREMENTIONED TROUGH...WITHIN REGION OF BROAD CYCLONIC CIRCULATION.
SERIES OF RELATIVELY MINOR SHORT WAVES WILL CONTINUE TO RIPPLE
SOUTH-SOUTHEAST THROUGH THE FLOW ACROSS THE AREA THROUGH THE
REMAINDER OF THE WEEK. GOES WATER VAPOR IMAGERY INDICATES A COUPLE
OF WEAK RIPPLES PASSED ACROSS THE REGION THIS MORNING...WITH A
SOMEWHAT MORE ROBUST SHORT WAVE NOTED UPSTREAM PROPAGATING SOUTH
ACROSS WESTERN ONTARIO. THESE SYSTEMS WILL TEND TO MODULATE
MID-LEVEL TEMPS AND INSTABILITY...ESPECIALLY WHEN JUXTAPOSED ATOP
AFTERNOON/EARLY EVENING DIURNAL WARMTH. FORECAST SOUNDINGS CONTINUE
TO INDICATE WEAK/SKINNY MLCAPES OF 200-300 J/KG THIS AFTERNOON...
WITH VISIBLE SATELLITE IMAGERY INDICATING CUMULUS CONGESTUS
DEVELOPMENT ALONG WEAK LOW LEVEL CONVERGENCE AXIS FROM NEAR ROCKFORD
TO THE SOUTHEAST SIDE OF CHICAGO/NORTHWEST INDIANA WHERE THE LAKE
BREEZE BOUNDARY WAS PROVIDING SOME ADDITIONAL CONVERGENCE.
CURRENT WEAK RADAR RETURNS EXPECTED TO CONTINUE TO SLOWLY GROW
THIS AFTERNOON THROUGH PEAK INSTABILITY...RESULTING IN ISOLATED TO
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. WANING
INSTABILITY AFTER SUNSET THIS EVENING WILL ALLOW A DECREASE IN
COVERAGE. SIMILAR TREND EXPECTED TOMORROW...THOUGH ONTARIO SHORT
WAVE LOOKS TO MOVE ACROSS AREA DURING THE MORNING...AS OPPOSED TO
DURING PERIOD OF BETTER INSTABILITY LATER IN THE DAY. THIS MAY
FAVOR SOUTHEAST PARTS OF THE CWA WHERE FORCING WILL DECREASE
LAST...WHILE DAYTIME INSTABILITY DEVELOPS. THESE DIURNAL
SHOWERS/ISOLATED THUNDERSTORMS...TIED TO CONVERGENCE ZONES AS IS
THE CASE TODAY...WILL CONTINUE IN SIMILAR FASHION THURSDAY AS
WELL. OBVIOUSLY...NOT ALL AREAS WILL SEE PRECIP AND THERE WILL BE
MANY DRY HOURS EVEN IN PLACES THAT DO. BY FRIDAY...ADDITIONAL
SHORT WAVE ENERGY WILL DROP INTO THE WESTERN PORTION OF THE TROUGH
FROM THE NORTHERN PLAINS AND WILL EFFECTIVELY RETROGRADE THE LONG
WAVE TROUGH AXIS WESTWARD INTO THE WESTERN LAKES AND
MISSISSIPPI/LOWER OHIO VALLEY AREA. LARGE SCALE HEIGHT FALLS WILL
LEAD TO SLIGHTLY COOLER MID-LEVEL TEMPS WHICH MAY SUPPORT GREATER
COVERAGE IN SHOWERS/THUNDERSTORMS FRIDAY AND SATURDAY BEFORE THE
TROUGH AXIS BECOMES MORE PROGRESSIVE AND MOVES OFF TO THE EAST
SATURDAY NIGHT AND SUNDAY. THUS HAVE MAINTAINED SOMEWHAT HIGHER
CHANCE POPS WITH A GREATER AERIAL COVERAGE FOR THOSE DAYTIME
PERIODS.

SURFACE HIGH PRESSURE THEN BUILDS ACROSS THE AREA SUNDAY...BEFORE
DRIFTING TO THE SOUTHEAST MONDAY AS ANOTHER SHORT WAVE TROUGH
APPROACHES IN NORTHWEST FLOW ALOFT. THIS MID-LEVEL WAVE IS
ACCOMPANIED BY A SURFACE LOW AND COLD FRONT...WHICH RETURNS THE
SHOWER/THUNDERSTORM THREAT FOR MONDAY/TUESDAY OF NEXT WEEK.

AS FOR TEMPS...MID AND UPPER 70S BEING REACHED THIS AFTERNOON WITH
CONSIDERABLE SUNSHINE. MID-LEVEL TEMPS CONTINUE TO MODERATE VERY
SLOWLY THROUGH THE PERIOD...WITH TO SLOWLY WARMING FROM UPPER 70S TO
AROUND 80 TO LOWER 80S OUTSIDE OF LAKE BREEZE AND SHOWERS INTO THE
WEEKEND. COLD FRONTAL PASSAGE LATE MONDAY WILL ALLOW SUBTLE
COOL-DOWN FROM THE NORTH BY TUESDAY.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* SHRA CURRENTLY ONGOING IN WISCONSIN MOST LIKELY TO DISSIPATE AS
  SUN GOES DOWN BUT CONCERN REMAINS THEY MAY HOLD TOGETHER.

* LAKE BREEZE LIKELY FOR MDW WEDNESDAY AFTN WITH NE/E WINDS. LAKE
  BREEZE QUESTIONABLE FOR ORD.

* ISOL TO SCT SHRA TO FORM WEDNESDAY EARLY AFTN AND PERSIST
  THROUGH THE AFTN INTO THE EVENING.

DANIELSON/RODRIGUEZ

//DISCUSSION...UPDATED 00Z...

CONVECTIVELY INDUCED OUTFLOW BOUNDARY HAS MERGED WITH LAKE BREEZE
AND PUSHED EASTWARD. WINDS AT ORD AND MDW HAVE SHIFTED TO WEST AT
10 KTS. SOME LINGERING SHRA NEAR ROCKFORD AND YORKVILLE HAVE
PERSISTED BUT WITH INSTABILITY DECREASING AS THE SUN SETS THESE
WILL DISSIPATE MUCH LIKE THE REST OF THE SHRA ACTIVITY HAS IN THE
PAST HOUR. CONCERNS THEN TURN TO SHRA IN WISCONSIN WITH BETTER
COVERAGE THAN STORMS IN OUR AREA. THESE STORMS HAVE PERSISTED ON A
DECENT SURFACE TROUGH AXIS AND WEAK UPPER LEVEL SUPPORT. THIS
ACTIVITY SHOULD BEGIN TO DIMINISH BUT WILL WATCH THESE AS THEY
APPROACH THE WISCONSIN ILLINOIS BORDER. HAVE INDICATED VCSH AT RFD
FROM 02Z TO 04Z DUE TO THIS ACTIVITY.

FOCUS THEN TURNS TO SHRA ACTIVITY WEDNESDAY AND LAKE BREEZE.
CONDITIONS WILL BE SIMILAR TO TODAY WITH WEST-NORTHWEST WINDS
INCREASING IN THE MORNING HOURS. STEEP LOW LEVEL LAPSE RATES AND A
WEAK SHORTWAVE WILL PROVIDE LIFT FOR SHRA FORMING AROUND 2PM AND
LINGERING INTO THE AFTERNOON AND EARLY EVENING. HAVE INDICATED
VCSH AT 19Z FOR ALL AIRPORTS. LOW CONFIDENCE IN ANY TSRA
DEVELOPING BUT COVERAGE WILL BE MINIMAL IF IT DOES OCCUR.
INTENSITY OF THE SHRA AND WEST WINDS WILL NEED TO BE MONITORED TO
GET A BETTER GRASP ON THE LAKE BREEZE WEDNESDAY AFTN. WILL LIKELY
SEE LAKE BREEZE PUSH THROUGH GYY AND MDW. AS ELUDED TO BEFORE
CONDITIONS WILL NEED TO BE WATCHED TO SEE IF LAKE BREEZE WILL PUSH
THROUGH ORD. LAKE BREEZE UNLIKELY AT DPA. SHRA DIMINISHES
WEDNESDAY EVENING AND WINDS WEAKEN AS SUN SETS.



DANIELSON/RODRIGUEZ


//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM CONFIDENCE SHRA IN WISCONSIN DISSIPATE BEFORE REACHING
  ORD AND MDW

* LOW CONFIDENCE FOR TIMING OF LAKE BREEZE REACHING ORD AND MDW.

* MEDIUM TO HIGH CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE
  AREA WEDNESDAY AFTERNOON. LOW CONFIDENCE IN TSRA DEVELOPMENT.

DANIELSON/RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY...SLIGHT CHANCE TSRA IN AFTN

FRIDAY...SLIGHT CHANCE TSRA IN AFTN

SATURDAY...CHANCE TSRA

SUNDAY...VFR

MONDAY...SLIGHT CHANCE TSRA

DANIELSON/RODRIGUEZ

&&

.MARINE...
210 PM CDT

HIGH PRESSURE IN THE NORTHERN AND CENTRAL PLAINS IS EXPECTED TO
WEAKEN SOME OVER THE COMING DAYS BUT GENERALLY REMAIN STATIONARY FOR
MOST OF THE WEEK AS AN UPPER LEVEL LOW PRESSURE SYSTEMS REMAINS
PARKED OVER JAMES BAY THROUGH SATURDAY. IN THIS PATTERN WEAK LOW
PRESSURE SYSTEMS WILL GLIDE SOUTHEAST DOWN THE LAKE AT TIMES...WITH
THE FIRST EXPECTED LATER TONIGHT INTO EARLY WEDNESDAY.

IN THIS STAGNANT PATTERN THE PRESSURE GRADIENT WILL REMAIN ON THE
LIGHTER SIDE AND WILL PROMOTE THE DEVELOPMENT OF LAKE BREEZES FOR
THE NEARSHORE WATERS AND VARIABLE WINDS OVER MUCH OF THE OPEN LAKE
AND WINDS GENERALLY 15 KT OR LESS.  KMD

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 300016
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
716 PM CDT TUE JUL 29 2014

.DISCUSSION...
218 PM CDT

FORECAST ISSUES CONTINUE TO FOCUS ON DAILY DIURNAL ISOLATED TO
SCATTERED SHOWER/THUNDERSTORM CHANCES...WITH VERY GRADUAL WARM UP IN
TEMPERATURES THROUGH THE FORECAST PERIOD AS LONG WAVE UPPER TROUGH
OVER EASTERN NORTH AMERICA EFFECTIVELY RETROGRADES THROUGH THE END
OF THE WEEK BEFORE FINALLY WEAKENING AND PROGRESSING OFF TO THE
NORTHEAST BY LATE WEEKEND AND EARLY NEXT WEEK.

WESTERN GREAT LAKES REGION REMAINS IN WESTERN PERIPHERY OF THIS
AFOREMENTIONED TROUGH...WITHIN REGION OF BROAD CYCLONIC CIRCULATION.
SERIES OF RELATIVELY MINOR SHORT WAVES WILL CONTINUE TO RIPPLE
SOUTH-SOUTHEAST THROUGH THE FLOW ACROSS THE AREA THROUGH THE
REMAINDER OF THE WEEK. GOES WATER VAPOR IMAGERY INDICATES A COUPLE
OF WEAK RIPPLES PASSED ACROSS THE REGION THIS MORNING...WITH A
SOMEWHAT MORE ROBUST SHORT WAVE NOTED UPSTREAM PROPAGATING SOUTH
ACROSS WESTERN ONTARIO. THESE SYSTEMS WILL TEND TO MODULATE
MID-LEVEL TEMPS AND INSTABILITY...ESPECIALLY WHEN JUXTAPOSED ATOP
AFTERNOON/EARLY EVENING DIURNAL WARMTH. FORECAST SOUNDINGS CONTINUE
TO INDICATE WEAK/SKINNY MLCAPES OF 200-300 J/KG THIS AFTERNOON...
WITH VISIBLE SATELLITE IMAGERY INDICATING CUMULUS CONGESTUS
DEVELOPMENT ALONG WEAK LOW LEVEL CONVERGENCE AXIS FROM NEAR ROCKFORD
TO THE SOUTHEAST SIDE OF CHICAGO/NORTHWEST INDIANA WHERE THE LAKE
BREEZE BOUNDARY WAS PROVIDING SOME ADDITIONAL CONVERGENCE.
CURRENT WEAK RADAR RETURNS EXPECTED TO CONTINUE TO SLOWLY GROW
THIS AFTERNOON THROUGH PEAK INSTABILITY...RESULTING IN ISOLATED TO
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. WANING
INSTABILITY AFTER SUNSET THIS EVENING WILL ALLOW A DECREASE IN
COVERAGE. SIMILAR TREND EXPECTED TOMORROW...THOUGH ONTARIO SHORT
WAVE LOOKS TO MOVE ACROSS AREA DURING THE MORNING...AS OPPOSED TO
DURING PERIOD OF BETTER INSTABILITY LATER IN THE DAY. THIS MAY
FAVOR SOUTHEAST PARTS OF THE CWA WHERE FORCING WILL DECREASE
LAST...WHILE DAYTIME INSTABILITY DEVELOPS. THESE DIURNAL
SHOWERS/ISOLATED THUNDERSTORMS...TIED TO CONVERGENCE ZONES AS IS
THE CASE TODAY...WILL CONTINUE IN SIMILAR FASHION THURSDAY AS
WELL. OBVIOUSLY...NOT ALL AREAS WILL SEE PRECIP AND THERE WILL BE
MANY DRY HOURS EVEN IN PLACES THAT DO. BY FRIDAY...ADDITIONAL
SHORT WAVE ENERGY WILL DROP INTO THE WESTERN PORTION OF THE TROUGH
FROM THE NORTHERN PLAINS AND WILL EFFECTIVELY RETROGRADE THE LONG
WAVE TROUGH AXIS WESTWARD INTO THE WESTERN LAKES AND
MISSISSIPPI/LOWER OHIO VALLEY AREA. LARGE SCALE HEIGHT FALLS WILL
LEAD TO SLIGHTLY COOLER MID-LEVEL TEMPS WHICH MAY SUPPORT GREATER
COVERAGE IN SHOWERS/THUNDERSTORMS FRIDAY AND SATURDAY BEFORE THE
TROUGH AXIS BECOMES MORE PROGRESSIVE AND MOVES OFF TO THE EAST
SATURDAY NIGHT AND SUNDAY. THUS HAVE MAINTAINED SOMEWHAT HIGHER
CHANCE POPS WITH A GREATER AERIAL COVERAGE FOR THOSE DAYTIME
PERIODS.

SURFACE HIGH PRESSURE THEN BUILDS ACROSS THE AREA SUNDAY...BEFORE
DRIFTING TO THE SOUTHEAST MONDAY AS ANOTHER SHORT WAVE TROUGH
APPROACHES IN NORTHWEST FLOW ALOFT. THIS MID-LEVEL WAVE IS
ACCOMPANIED BY A SURFACE LOW AND COLD FRONT...WHICH RETURNS THE
SHOWER/THUNDERSTORM THREAT FOR MONDAY/TUESDAY OF NEXT WEEK.

AS FOR TEMPS...MID AND UPPER 70S BEING REACHED THIS AFTERNOON WITH
CONSIDERABLE SUNSHINE. MID-LEVEL TEMPS CONTINUE TO MODERATE VERY
SLOWLY THROUGH THE PERIOD...WITH TO SLOWLY WARMING FROM UPPER 70S TO
AROUND 80 TO LOWER 80S OUTSIDE OF LAKE BREEZE AND SHOWERS INTO THE
WEEKEND. COLD FRONTAL PASSAGE LATE MONDAY WILL ALLOW SUBTLE
COOL-DOWN FROM THE NORTH BY TUESDAY.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* SHRA CURRENTLY ONGOING IN WISCONSIN MOST LIKELY TO DISSIPATE AS
  SUN GOES DOWN BUT CONCERN REMAINS THEY MAY HOLD TOGETHER.

* LAKE BREEZE LIKELY FOR MDW WEDNESDAY AFTN WITH NE/E WINDS. LAKE
  BREEZE QUESTIONABLE FOR ORD.

* ISOL TO SCT SHRA TO FORM WEDNESDAY EARLY AFTN AND PERSIST
  THROUGH THE AFTN INTO THE EVENING.

DANIELSON/RODRIGUEZ

//DISCUSSION...UPDATED 00Z...

CONVECTIVELY INDUCED OUTFLOW BOUNDARY HAS MERGED WITH LAKE BREEZE
AND PUSHED EASTWARD. WINDS AT ORD AND MDW HAVE SHIFTED TO WEST AT
10 KTS. SOME LINGERING SHRA NEAR ROCKFORD AND YORKVILLE HAVE
PERSISTED BUT WITH INSTABILITY DECREASING AS THE SUN SETS THESE
WILL DISSIPATE MUCH LIKE THE REST OF THE SHRA ACTIVITY HAS IN THE
PAST HOUR. CONCERNS THEN TURN TO SHRA IN WISCONSIN WITH BETTER
COVERAGE THAN STORMS IN OUR AREA. THESE STORMS HAVE PERSISTED ON A
DECENT SURFACE TROUGH AXIS AND WEAK UPPER LEVEL SUPPORT. THIS
ACTIVITY SHOULD BEGIN TO DIMINISH BUT WILL WATCH THESE AS THEY
APPROACH THE WISCONSIN ILLINOIS BORDER. HAVE INDICATED VCSH AT RFD
FROM 02Z TO 04Z DUE TO THIS ACTIVITY.

FOCUS THEN TURNS TO SHRA ACTIVITY WEDNESDAY AND LAKE BREEZE.
CONDITIONS WILL BE SIMILAR TO TODAY WITH WEST-NORTHWEST WINDS
INCREASING IN THE MORNING HOURS. STEEP LOW LEVEL LAPSE RATES AND A
WEAK SHORTWAVE WILL PROVIDE LIFT FOR SHRA FORMING AROUND 2PM AND
LINGERING INTO THE AFTERNOON AND EARLY EVENING. HAVE INDICATED
VCSH AT 19Z FOR ALL AIRPORTS. LOW CONFIDENCE IN ANY TSRA
DEVELOPING BUT COVERAGE WILL BE MINIMAL IF IT DOES OCCUR.
INTENSITY OF THE SHRA AND WEST WINDS WILL NEED TO BE MONITORED TO
GET A BETTER GRASP ON THE LAKE BREEZE WEDNESDAY AFTN. WILL LIKELY
SEE LAKE BREEZE PUSH THROUGH GYY AND MDW. AS ELUDED TO BEFORE
CONDITIONS WILL NEED TO BE WATCHED TO SEE IF LAKE BREEZE WILL PUSH
THROUGH ORD. LAKE BREEZE UNLIKELY AT DPA. SHRA DIMINISHES
WEDNESDAY EVENING AND WINDS WEAKEN AS SUN SETS.



DANIELSON/RODRIGUEZ


//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* MEDIUM CONFIDENCE SHRA IN WISCONSIN DISSIPATE BEFORE REACHING
  ORD AND MDW

* LOW CONFIDENCE FOR TIMING OF LAKE BREEZE REACHING ORD AND MDW.

* MEDIUM TO HIGH CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE
  AREA WEDNESDAY AFTERNOON. LOW CONFIDENCE IN TSRA DEVELOPMENT.

DANIELSON/RODRIGUEZ

//OUTLOOK FOR ORD/MDW FOR 12Z THURSDAY-12Z TUESDAY...UPDATED 00Z...

THURSDAY...SLIGHT CHANCE TSRA IN AFTN

FRIDAY...SLIGHT CHANCE TSRA IN AFTN

SATURDAY...CHANCE TSRA

SUNDAY...VFR

MONDAY...SLIGHT CHANCE TSRA

DANIELSON/RODRIGUEZ

&&

.MARINE...
210 PM CDT

HIGH PRESSURE IN THE NORTHERN AND CENTRAL PLAINS IS EXPECTED TO
WEAKEN SOME OVER THE COMING DAYS BUT GENERALLY REMAIN STATIONARY FOR
MOST OF THE WEEK AS AN UPPER LEVEL LOW PRESSURE SYSTEMS REMAINS
PARKED OVER JAMES BAY THROUGH SATURDAY. IN THIS PATTERN WEAK LOW
PRESSURE SYSTEMS WILL GLIDE SOUTHEAST DOWN THE LAKE AT TIMES...WITH
THE FIRST EXPECTED LATER TONIGHT INTO EARLY WEDNESDAY.

IN THIS STAGNANT PATTERN THE PRESSURE GRADIENT WILL REMAIN ON THE
LIGHTER SIDE AND WILL PROMOTE THE DEVELOPMENT OF LAKE BREEZES FOR
THE NEARSHORE WATERS AND VARIABLE WINDS OVER MUCH OF THE OPEN LAKE
AND WINDS GENERALLY 15 KT OR LESS.  KMD

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KILX 292324
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
624 PM CDT Tue Jul 29 2014

.DISCUSSION...
ISSUED 230 PM CDT Tue Jul 29 2014

Latest radar mosaics showing isolated showers and thunderstorms
from near Rockford southeast into central Indiana, along a weak
convergence boundary. HRRR suggests some of this may clip the far
northeast CWA later this afternoon, where 20% PoP`s remain in
place. Am planning on leaving the evening dry, as any lingering
showers will quickly be fizzling as sunset approaches.

Upper air analysis continues to show strong ridging west of the
Rockies northward into Canada, with the eastern states and
provinces dominated by a broad long wave trough anchored via an
upper low spinning north of the Great Lakes. The long range
pattern does not change during the forecast period, except that
the upper low opens up some and starts to lift northeast. Some
hints exist that it may return early next week, but the associated
cooler surge looks to stay north of Illinois at this point.

Little change in the going forecast is needed. Temperatures are
expected to rise a couple degrees, with lower 80s for highs and
upper 50s-lower 60s for lows from Wednesday through the weekend,
and slightly warmer early next week. Precipitation chances remain
focused on Friday and Saturday, mainly diurnally driven, as weak
shortwaves pivot through in the broader upper troughs.

Geelhart

&&

.AVIATION...
ISSUED 624 PM CDT Tue Jul 29 2014

Skies will quickly clear this evening and winds will become light
out of the west. These VFR conditions will continue at all TAF
sites next 24hrs. A line of showers and isolated thunderstorms was
dropping south through northeast IL late this afternoon. This
could reach areas north of Champaign, but looks like it is moving
slightly east of south and should miss the TAF site this evening.
Will not have any pcpn mentioned at CMI but will continue to
monitor trends and see if VCSH is needed at some point. Pcpn
should also be dissipating as it moves south. Winds tomorrow will
be westerly at around 10kts with scattered CU around 5kft.

Auten

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KILX 292324
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
624 PM CDT Tue Jul 29 2014

.DISCUSSION...
ISSUED 230 PM CDT Tue Jul 29 2014

Latest radar mosaics showing isolated showers and thunderstorms
from near Rockford southeast into central Indiana, along a weak
convergence boundary. HRRR suggests some of this may clip the far
northeast CWA later this afternoon, where 20% PoP`s remain in
place. Am planning on leaving the evening dry, as any lingering
showers will quickly be fizzling as sunset approaches.

Upper air analysis continues to show strong ridging west of the
Rockies northward into Canada, with the eastern states and
provinces dominated by a broad long wave trough anchored via an
upper low spinning north of the Great Lakes. The long range
pattern does not change during the forecast period, except that
the upper low opens up some and starts to lift northeast. Some
hints exist that it may return early next week, but the associated
cooler surge looks to stay north of Illinois at this point.

Little change in the going forecast is needed. Temperatures are
expected to rise a couple degrees, with lower 80s for highs and
upper 50s-lower 60s for lows from Wednesday through the weekend,
and slightly warmer early next week. Precipitation chances remain
focused on Friday and Saturday, mainly diurnally driven, as weak
shortwaves pivot through in the broader upper troughs.

Geelhart

&&

.AVIATION...
ISSUED 624 PM CDT Tue Jul 29 2014

Skies will quickly clear this evening and winds will become light
out of the west. These VFR conditions will continue at all TAF
sites next 24hrs. A line of showers and isolated thunderstorms was
dropping south through northeast IL late this afternoon. This
could reach areas north of Champaign, but looks like it is moving
slightly east of south and should miss the TAF site this evening.
Will not have any pcpn mentioned at CMI but will continue to
monitor trends and see if VCSH is needed at some point. Pcpn
should also be dissipating as it moves south. Winds tomorrow will
be westerly at around 10kts with scattered CU around 5kft.

Auten

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$







000
FXUS63 KLOT 292212
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
512 PM CDT TUE JUL 29 2014

.DISCUSSION...
218 PM CDT

FORECAST ISSUES CONTINUE TO FOCUS ON DAILY DIURNAL ISOLATED TO
SCATTERED SHOWER/THUNDERSTORM CHANCES...WITH VERY GRADUAL WARM UP IN
TEMPERATURES THROUGH THE FORECAST PERIOD AS LONG WAVE UPPER TROUGH
OVER EASTERN NORTH AMERICA EFFECTIVELY RETROGRADES THROUGH THE END
OF THE WEEK BEFORE FINALLY WEAKENING AND PROGRESSING OFF TO THE
NORTHEAST BY LATE WEEKEND AND EARLY NEXT WEEK.

WESTERN GREAT LAKES REGION REMAINS IN WESTERN PERIPHERY OF THIS
AFOREMENTIONED TROUGH...WITHIN REGION OF BROAD CYCLONIC CIRCULATION.
SERIES OF RELATIVELY MINOR SHORT WAVES WILL CONTINUE TO RIPPLE
SOUTH-SOUTHEAST THROUGH THE FLOW ACROSS THE AREA THROUGH THE
REMAINDER OF THE WEEK. GOES WATER VAPOR IMAGERY INDICATES A COUPLE
OF WEAK RIPPLES PASSED ACROSS THE REGION THIS MORNING...WITH A
SOMEWHAT MORE ROBUST SHORT WAVE NOTED UPSTREAM PROPAGATING SOUTH
ACROSS WESTERN ONTARIO. THESE SYSTEMS WILL TEND TO MODULATE
MID-LEVEL TEMPS AND INSTABILITY...ESPECIALLY WHEN JUXTAPOSED ATOP
AFTERNOON/EARLY EVENING DIURNAL WARMTH. FORECAST SOUNDINGS CONTINUE
TO INDICATE WEAK/SKINNY MLCAPES OF 200-300 J/KG THIS AFTERNOON...
WITH VISIBLE SATELLITE IMAGERY INDICATING CUMULUS CONGESTUS
DEVELOPMENT ALONG WEAK LOW LEVEL CONVERGENCE AXIS FROM NEAR ROCKFORD
TO THE SOUTHEAST SIDE OF CHICAGO/NORTHWEST INDIANA WHERE THE LAKE
BREEZE BOUNDARY WAS PROVIDING SOME ADDITIONAL CONVERGENCE.
CURRENT WEAK RADAR RETURNS EXPECTED TO CONTINUE TO SLOWLY GROW
THIS AFTERNOON THROUGH PEAK INSTABILITY...RESULTING IN ISOLATED TO
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. WANING
INSTABILITY AFTER SUNSET THIS EVENING WILL ALLOW A DECREASE IN
COVERAGE. SIMILAR TREND EXPECTED TOMORROW...THOUGH ONTARIO SHORT
WAVE LOOKS TO MOVE ACROSS AREA DURING THE MORNING...AS OPPOSED TO
DURING PERIOD OF BETTER INSTABILITY LATER IN THE DAY. THIS MAY
FAVOR SOUTHEAST PARTS OF THE CWA WHERE FORCING WILL DECREASE
LAST...WHILE DAYTIME INSTABILITY DEVELOPS. THESE DIURNAL
SHOWERS/ISOLATED THUNDERSTORMS...TIED TO CONVERGENCE ZONES AS IS
THE CASE TODAY...WILL CONTINUE IN SIMILAR FASHION THURSDAY AS
WELL. OBVIOUSLY...NOT ALL AREAS WILL SEE PRECIP AND THERE WILL BE
MANY DRY HOURS EVEN IN PLACES THAT DO. BY FRIDAY...ADDITIONAL
SHORT WAVE ENERGY WILL DROP INTO THE WESTERN PORTION OF THE TROUGH
FROM THE NORTHERN PLAINS AND WILL EFFECTIVELY RETROGRADE THE LONG
WAVE TROUGH AXIS WESTWARD INTO THE WESTERN LAKES AND
MISSISSIPPI/LOWER OHIO VALLEY AREA. LARGE SCALE HEIGHT FALLS WILL
LEAD TO SLIGHTLY COOLER MID-LEVEL TEMPS WHICH MAY SUPPORT GREATER
COVERAGE IN SHOWERS/THUNDERSTORMS FRIDAY AND SATURDAY BEFORE THE
TROUGH AXIS BECOMES MORE PROGRESSIVE AND MOVES OFF TO THE EAST
SATURDAY NIGHT AND SUNDAY. THUS HAVE MAINTAINED SOMEWHAT HIGHER
CHANCE POPS WITH A GREATER AERIAL COVERAGE FOR THOSE DAYTIME
PERIODS.

SURFACE HIGH PRESSURE THEN BUILDS ACROSS THE AREA SUNDAY...BEFORE
DRIFTING TO THE SOUTHEAST MONDAY AS ANOTHER SHORT WAVE TROUGH
APPROACHES IN NORTHWEST FLOW ALOFT. THIS MID-LEVEL WAVE IS
ACCOMPANIED BY A SURFACE LOW AND COLD FRONT...WHICH RETURNS THE
SHOWER/THUNDERSTORM THREAT FOR MONDAY/TUESDAY OF NEXT WEEK.

AS FOR TEMPS...MID AND UPPER 70S BEING REACHED THIS AFTERNOON WITH
CONSIDERABLE SUNSHINE. MID-LEVEL TEMPS CONTINUE TO MODERATE VERY
SLOWLY THROUGH THE PERIOD...WITH TO SLOWLY WARMING FROM UPPER 70S TO
AROUND 80 TO LOWER 80S OUTSIDE OF LAKE BREEZE AND SHOWERS INTO THE
WEEKEND. COLD FRONTAL PASSAGE LATE MONDAY WILL ALLOW SUBTLE
COOL-DOWN FROM THE NORTH BY TUESDAY.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* LAKE BREEZE IMPACTING MDW ONLY THIS AFTN WITH NE/E WINDS IN
  PLACE. BREEZE STILL LOOKS TO STALL EAST OF ORD.

* ISOL TO SCT SHRA THIS AFTN INTO THE EARLY EVENING...BUT WITH
  BETTER COVERAGE REMAINING WEST.

* LAKE BREEZE POSSIBLE AGAIN ON WEDNESDAY AFTERNOON.

KJB/RODRIGUEZ/DANIELSON

//DISCUSSION...UPDATED 18Z...

OBSERVATIONS NEAR THE SHORES OF LAKE MICHIGAN ARE SHOWING SIGNS OF A
LAKE BREEZE DEVELOPING. THIS BOUNDARY WILL LIKELY PUSH INLAND A
LITTLE THIS AFTERNOON...IMPACTING KGYY AND POSSIBLY KMDW LATER IN
THE AFTERNOON. HOWEVER...I HAVE SOME DOUBTS THAT IT WILL MAKE IT TO
MDW GIVEN THE 12-15 KT OF 925 MB WEST-NORTHWESTERLY FLOW THAT IT
WILL BE WORKING AGAINST. FOR NOW...I WILL CONTINUE TO MONITOR THE
TRENDS OF THIS LAKE BREEZE AND MAKE A DECISION LATER OF WHETHER OR
NOT TO REMOVE THE WIND SHIFT FROM THE MDW TAF.

OTHERWISE...THE OTHER CONCERN LATER THIS AFTERNOON AND EVENING IS
THE THREAT FOR SCATTERED SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE
AREA. IT STILL APPEARS THE BEST TIMING FOR ANY ACTIVITY WOULD BE
AFTER 21 UTC THROUGH AROUND 02 UTC THIS EVENING. DUE TO THE
SCATTERED NATURE EXPECTED...I HAVE CONTINUED TO HANDLE THIS CHANCE
WITH A VCSH.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* HIGH CONFIDENCE FOR LAKE BREEZE AT MDW. MEDIUM CONFIDENCE THAT
  LAKE BREEZE WILL STAY EAST OF ORD.

* MEDIUM CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE AREA THIS
  AFTERNOON.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB/RODRIGUEZ/DANIELSON

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT...VFR.

THURSDAY THROUGH SATURDAY...PREDOMINANTLY VFR...WITH A CHANCE OF
TSRA IN MAINLY THE AFTERNOON & EARLY EVENING.

SUNDAY...VFR.

MONDAY...SCHC TSRA.

JEE

&&

.MARINE...
210 PM CDT

HIGH PRESSURE IN THE NORTHERN AND CENTRAL PLAINS IS EXPECTED TO
WEAKEN SOME OVER THE COMING DAYS BUT GENERALLY REMAIN STATIONARY FOR
MOST OF THE WEEK AS AN UPPER LEVEL LOW PRESSURE SYSTEMS REMAINS
PARKED OVER JAMES BAY THROUGH SATURDAY. IN THIS PATTERN WEAK LOW
PRESSURE SYSTEMS WILL GLIDE SOUTHEAST DOWN THE LAKE AT TIMES...WITH
THE FIRST EXPECTED LATER TONIGHT INTO EARLY WEDNESDAY.

IN THIS STAGNANT PATTERN THE PRESSURE GRADIENT WILL REMAIN ON THE
LIGHTER SIDE AND WILL PROMOTE THE DEVELOPMENT OF LAKE BREEZES FOR
THE NEARSHORE WATERS AND VARIABLE WINDS OVER MUCH OF THE OPEN LAKE
AND WINDS GENERALLY 15 KT OR LESS.  KMD

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 292212
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
512 PM CDT TUE JUL 29 2014

.DISCUSSION...
218 PM CDT

FORECAST ISSUES CONTINUE TO FOCUS ON DAILY DIURNAL ISOLATED TO
SCATTERED SHOWER/THUNDERSTORM CHANCES...WITH VERY GRADUAL WARM UP IN
TEMPERATURES THROUGH THE FORECAST PERIOD AS LONG WAVE UPPER TROUGH
OVER EASTERN NORTH AMERICA EFFECTIVELY RETROGRADES THROUGH THE END
OF THE WEEK BEFORE FINALLY WEAKENING AND PROGRESSING OFF TO THE
NORTHEAST BY LATE WEEKEND AND EARLY NEXT WEEK.

WESTERN GREAT LAKES REGION REMAINS IN WESTERN PERIPHERY OF THIS
AFOREMENTIONED TROUGH...WITHIN REGION OF BROAD CYCLONIC CIRCULATION.
SERIES OF RELATIVELY MINOR SHORT WAVES WILL CONTINUE TO RIPPLE
SOUTH-SOUTHEAST THROUGH THE FLOW ACROSS THE AREA THROUGH THE
REMAINDER OF THE WEEK. GOES WATER VAPOR IMAGERY INDICATES A COUPLE
OF WEAK RIPPLES PASSED ACROSS THE REGION THIS MORNING...WITH A
SOMEWHAT MORE ROBUST SHORT WAVE NOTED UPSTREAM PROPAGATING SOUTH
ACROSS WESTERN ONTARIO. THESE SYSTEMS WILL TEND TO MODULATE
MID-LEVEL TEMPS AND INSTABILITY...ESPECIALLY WHEN JUXTAPOSED ATOP
AFTERNOON/EARLY EVENING DIURNAL WARMTH. FORECAST SOUNDINGS CONTINUE
TO INDICATE WEAK/SKINNY MLCAPES OF 200-300 J/KG THIS AFTERNOON...
WITH VISIBLE SATELLITE IMAGERY INDICATING CUMULUS CONGESTUS
DEVELOPMENT ALONG WEAK LOW LEVEL CONVERGENCE AXIS FROM NEAR ROCKFORD
TO THE SOUTHEAST SIDE OF CHICAGO/NORTHWEST INDIANA WHERE THE LAKE
BREEZE BOUNDARY WAS PROVIDING SOME ADDITIONAL CONVERGENCE.
CURRENT WEAK RADAR RETURNS EXPECTED TO CONTINUE TO SLOWLY GROW
THIS AFTERNOON THROUGH PEAK INSTABILITY...RESULTING IN ISOLATED TO
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. WANING
INSTABILITY AFTER SUNSET THIS EVENING WILL ALLOW A DECREASE IN
COVERAGE. SIMILAR TREND EXPECTED TOMORROW...THOUGH ONTARIO SHORT
WAVE LOOKS TO MOVE ACROSS AREA DURING THE MORNING...AS OPPOSED TO
DURING PERIOD OF BETTER INSTABILITY LATER IN THE DAY. THIS MAY
FAVOR SOUTHEAST PARTS OF THE CWA WHERE FORCING WILL DECREASE
LAST...WHILE DAYTIME INSTABILITY DEVELOPS. THESE DIURNAL
SHOWERS/ISOLATED THUNDERSTORMS...TIED TO CONVERGENCE ZONES AS IS
THE CASE TODAY...WILL CONTINUE IN SIMILAR FASHION THURSDAY AS
WELL. OBVIOUSLY...NOT ALL AREAS WILL SEE PRECIP AND THERE WILL BE
MANY DRY HOURS EVEN IN PLACES THAT DO. BY FRIDAY...ADDITIONAL
SHORT WAVE ENERGY WILL DROP INTO THE WESTERN PORTION OF THE TROUGH
FROM THE NORTHERN PLAINS AND WILL EFFECTIVELY RETROGRADE THE LONG
WAVE TROUGH AXIS WESTWARD INTO THE WESTERN LAKES AND
MISSISSIPPI/LOWER OHIO VALLEY AREA. LARGE SCALE HEIGHT FALLS WILL
LEAD TO SLIGHTLY COOLER MID-LEVEL TEMPS WHICH MAY SUPPORT GREATER
COVERAGE IN SHOWERS/THUNDERSTORMS FRIDAY AND SATURDAY BEFORE THE
TROUGH AXIS BECOMES MORE PROGRESSIVE AND MOVES OFF TO THE EAST
SATURDAY NIGHT AND SUNDAY. THUS HAVE MAINTAINED SOMEWHAT HIGHER
CHANCE POPS WITH A GREATER AERIAL COVERAGE FOR THOSE DAYTIME
PERIODS.

SURFACE HIGH PRESSURE THEN BUILDS ACROSS THE AREA SUNDAY...BEFORE
DRIFTING TO THE SOUTHEAST MONDAY AS ANOTHER SHORT WAVE TROUGH
APPROACHES IN NORTHWEST FLOW ALOFT. THIS MID-LEVEL WAVE IS
ACCOMPANIED BY A SURFACE LOW AND COLD FRONT...WHICH RETURNS THE
SHOWER/THUNDERSTORM THREAT FOR MONDAY/TUESDAY OF NEXT WEEK.

AS FOR TEMPS...MID AND UPPER 70S BEING REACHED THIS AFTERNOON WITH
CONSIDERABLE SUNSHINE. MID-LEVEL TEMPS CONTINUE TO MODERATE VERY
SLOWLY THROUGH THE PERIOD...WITH TO SLOWLY WARMING FROM UPPER 70S TO
AROUND 80 TO LOWER 80S OUTSIDE OF LAKE BREEZE AND SHOWERS INTO THE
WEEKEND. COLD FRONTAL PASSAGE LATE MONDAY WILL ALLOW SUBTLE
COOL-DOWN FROM THE NORTH BY TUESDAY.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* LAKE BREEZE IMPACTING MDW ONLY THIS AFTN WITH NE/E WINDS IN
  PLACE. BREEZE STILL LOOKS TO STALL EAST OF ORD.

* ISOL TO SCT SHRA THIS AFTN INTO THE EARLY EVENING...BUT WITH
  BETTER COVERAGE REMAINING WEST.

* LAKE BREEZE POSSIBLE AGAIN ON WEDNESDAY AFTERNOON.

KJB/RODRIGUEZ/DANIELSON

//DISCUSSION...UPDATED 18Z...

OBSERVATIONS NEAR THE SHORES OF LAKE MICHIGAN ARE SHOWING SIGNS OF A
LAKE BREEZE DEVELOPING. THIS BOUNDARY WILL LIKELY PUSH INLAND A
LITTLE THIS AFTERNOON...IMPACTING KGYY AND POSSIBLY KMDW LATER IN
THE AFTERNOON. HOWEVER...I HAVE SOME DOUBTS THAT IT WILL MAKE IT TO
MDW GIVEN THE 12-15 KT OF 925 MB WEST-NORTHWESTERLY FLOW THAT IT
WILL BE WORKING AGAINST. FOR NOW...I WILL CONTINUE TO MONITOR THE
TRENDS OF THIS LAKE BREEZE AND MAKE A DECISION LATER OF WHETHER OR
NOT TO REMOVE THE WIND SHIFT FROM THE MDW TAF.

OTHERWISE...THE OTHER CONCERN LATER THIS AFTERNOON AND EVENING IS
THE THREAT FOR SCATTERED SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE
AREA. IT STILL APPEARS THE BEST TIMING FOR ANY ACTIVITY WOULD BE
AFTER 21 UTC THROUGH AROUND 02 UTC THIS EVENING. DUE TO THE
SCATTERED NATURE EXPECTED...I HAVE CONTINUED TO HANDLE THIS CHANCE
WITH A VCSH.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* HIGH CONFIDENCE FOR LAKE BREEZE AT MDW. MEDIUM CONFIDENCE THAT
  LAKE BREEZE WILL STAY EAST OF ORD.

* MEDIUM CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE AREA THIS
  AFTERNOON.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB/RODRIGUEZ/DANIELSON

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT...VFR.

THURSDAY THROUGH SATURDAY...PREDOMINANTLY VFR...WITH A CHANCE OF
TSRA IN MAINLY THE AFTERNOON & EARLY EVENING.

SUNDAY...VFR.

MONDAY...SCHC TSRA.

JEE

&&

.MARINE...
210 PM CDT

HIGH PRESSURE IN THE NORTHERN AND CENTRAL PLAINS IS EXPECTED TO
WEAKEN SOME OVER THE COMING DAYS BUT GENERALLY REMAIN STATIONARY FOR
MOST OF THE WEEK AS AN UPPER LEVEL LOW PRESSURE SYSTEMS REMAINS
PARKED OVER JAMES BAY THROUGH SATURDAY. IN THIS PATTERN WEAK LOW
PRESSURE SYSTEMS WILL GLIDE SOUTHEAST DOWN THE LAKE AT TIMES...WITH
THE FIRST EXPECTED LATER TONIGHT INTO EARLY WEDNESDAY.

IN THIS STAGNANT PATTERN THE PRESSURE GRADIENT WILL REMAIN ON THE
LIGHTER SIDE AND WILL PROMOTE THE DEVELOPMENT OF LAKE BREEZES FOR
THE NEARSHORE WATERS AND VARIABLE WINDS OVER MUCH OF THE OPEN LAKE
AND WINDS GENERALLY 15 KT OR LESS.  KMD

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 291959
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
259 PM CDT TUE JUL 29 2014

.DISCUSSION...
218 PM CDT

FORECAST ISSUES CONTINUE TO FOCUS ON DAILY DIURNAL ISOLATED TO
SCATTERED SHOWER/THUNDERSTORM CHANCES...WITH VERY GRADUAL WARM UP IN
TEMPERATURES THROUGH THE FORECAST PERIOD AS LONG WAVE UPPER TROUGH
OVER EASTERN NORTH AMERICA EFFECTIVELY RETROGRADES THROUGH THE END
OF THE WEEK BEFORE FINALLY WEAKENING AND PROGRESSING OFF TO THE
NORTHEAST BY LATE WEEKEND AND EARLY NEXT WEEK.

WESTERN GREAT LAKES REGION REMAINS IN WESTERN PERIPHERY OF THIS
AFOREMENTIONED TROUGH...WITHIN REGION OF BROAD CYCLONIC CIRCULATION.
SERIES OF RELATIVELY MINOR SHORT WAVES WILL CONTINUE TO RIPPLE
SOUTH-SOUTHEAST THROUGH THE FLOW ACROSS THE AREA THROUGH THE
REMAINDER OF THE WEEK. GOES WATER VAPOR IMAGERY INDICATES A COUPLE
OF WEAK RIPPLES PASSED ACROSS THE REGION THIS MORNING...WITH A
SOMEWHAT MORE ROBUST SHORT WAVE NOTED UPSTREAM PROPAGATING SOUTH
ACROSS WESTERN ONTARIO. THESE SYSTEMS WILL TEND TO MODULATE
MID-LEVEL TEMPS AND INSTABILITY...ESPECIALLY WHEN JUXTAPOSED ATOP
AFTERNOON/EARLY EVENING DIURNAL WARMTH. FORECAST SOUNDINGS CONTINUE
TO INDICATE WEAK/SKINNY MLCAPES OF 200-300 J/KG THIS AFTERNOON...
WITH VISIBLE SATELLITE IMAGERY INDICATING CUMULUS CONGESTUS
DEVELOPMENT ALONG WEAK LOW LEVEL CONVERGENCE AXIS FROM NEAR ROCKFORD
TO THE SOUTHEAST SIDE OF CHICAGO/NORTHWEST INDIANA WHERE THE LAKE
BREEZE BOUNDARY WAS PROVIDING SOME ADDITIONAL CONVERGENCE.
CURRENT WEAK RADAR RETURNS EXPECTED TO CONTINUE TO SLOWLY GROW
THIS AFTERNOON THROUGH PEAK INSTABILITY...RESULTING IN ISOLATED TO
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. WANING
INSTABILITY AFTER SUNSET THIS EVENING WILL ALLOW A DECREASE IN
COVERAGE. SIMILAR TREND EXPECTED TOMORROW...THOUGH ONTARIO SHORT
WAVE LOOKS TO MOVE ACROSS AREA DURING THE MORNING...AS OPPOSED TO
DURING PERIOD OF BETTER INSTABILITY LATER IN THE DAY. THIS MAY
FAVOR SOUTHEAST PARTS OF THE CWA WHERE FORCING WILL DECREASE
LAST...WHILE DAYTIME INSTABILITY DEVELOPS. THESE DIURNAL
SHOWERS/ISOLATED THUNDERSTORMS...TIED TO CONVERGENCE ZONES AS IS
THE CASE TODAY...WILL CONTINUE IN SIMILAR FASHION THURSDAY AS
WELL. OBVIOUSLY...NOT ALL AREAS WILL SEE PRECIP AND THERE WILL BE
MANY DRY HOURS EVEN IN PLACES THAT DO. BY FRIDAY...ADDITIONAL
SHORT WAVE ENERGY WILL DROP INTO THE WESTERN PORTION OF THE TROUGH
FROM THE NORTHERN PLAINS AND WILL EFFECTIVELY RETROGRADE THE LONG
WAVE TROUGH AXIS WESTWARD INTO THE WESTERN LAKES AND
MISSISSIPPI/LOWER OHIO VALLEY AREA. LARGE SCALE HEIGHT FALLS WILL
LEAD TO SLIGHTLY COOLER MID-LEVEL TEMPS WHICH MAY SUPPORT GREATER
COVERAGE IN SHOWERS/THUNDERSTORMS FRIDAY AND SATURDAY BEFORE THE
TROUGH AXIS BECOMES MORE PROGRESSIVE AND MOVES OFF TO THE EAST
SATURDAY NIGHT AND SUNDAY. THUS HAVE MAINTAINED SOMEWHAT HIGHER
CHANCE POPS WITH A GREATER AERIAL COVERAGE FOR THOSE DAYTIME
PERIODS.

SURFACE HIGH PRESSURE THEN BUILDS ACROSS THE AREA SUNDAY...BEFORE
DRIFTING TO THE SOUTHEAST MONDAY AS ANOTHER SHORT WAVE TROUGH
APPROACHES IN NORTHWEST FLOW ALOFT. THIS MID-LEVEL WAVE IS
ACCOMPANIED BY A SURFACE LOW AND COLD FRONT...WHICH RETURNS THE
SHOWER/THUNDERSTORM THREAT FOR MONDAY/TUESDAY OF NEXT WEEK.

AS FOR TEMPS...MID AND UPPER 70S BEING REACHED THIS AFTERNOON WITH
CONSIDERABLE SUNSHINE. MID-LEVEL TEMPS CONTINUE TO MODERATE VERY
SLOWLY THROUGH THE PERIOD...WITH TO SLOWLY WARMING FROM UPPER 70S TO
AROUND 80 TO LOWER 80S OUTSIDE OF LAKE BREEZE AND SHOWERS INTO THE
WEEKEND. COLD FRONTAL PASSAGE LATE MONDAY WILL ALLOW SUBTLE
COOL-DOWN FROM THE NORTH BY TUESDAY.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* LAKE BREEZE MAY IMPACT MDW LATER THIS AFTN WITH WINDS SHIFTING
  TO NE OR E BEHIND IT. BREEZE LOOKS TO STALL BEFORE REACHING
  ORD.

* ISOL TO SCT SHRA DEVELOP THIS AFTN INTO THE EARLY EVENING. MAY
  SEE A FEW THUNDERSTORMS AS WELL.

* LAKE BREEZE POSSIBLE AGAIN ON WEDNESDAY AFTERNOON.

KJB

//DISCUSSION...UPDATED 18Z...

OBSERVATIONS NEAR THE SHORES OF LAKE MICHIGAN ARE SHOWING SIGNS OF A
LAKE BREEZE DEVELOPING. THIS BOUNDARY WILL LIKELY PUSH INLAND A
LITTLE THIS AFTERNOON...IMPACTING KGYY AND POSSIBLY KMDW LATER IN
THE AFTERNOON. HOWEVER...I HAVE SOME DOUBTS THAT IT WILL MAKE IT TO
MDW GIVEN THE 12-15 KT OF 925 MB WEST-NORTHWESTERLY FLOW THAT IT
WILL BE WORKING AGAINST. FOR NOW...I WILL CONTINUE TO MONITOR THE
TRENDS OF THIS LAKE BREEZE AND MAKE A DECISION LATER OF WHETHER OR
NOT TO REMOVE THE WIND SHIFT FROM THE MDW TAF.

OTHERWISE...THE OTHER CONCERN LATER THIS AFTERNOON AND EVENING IS
THE THREAT FOR SCATTERED SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE
AREA. IT STILL APPEARS THE BEST TIMING FOR ANY ACTIVITY WOULD BE
AFTER 21 UTC THROUGH AROUND 02 UTC THIS EVENING. DUE TO THE
SCATTERED NATURE EXPECTED...I HAVE CONTINUED TO HANDLE THIS CHANCE
WITH A VCSH.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* HIGH CONFIDENECE WILL LAKE BREEZE GETTING TO MDW BY 21 UTC. LOW
  CONFIDENCE IN LAKE BREEZE IMPACTING ORD THIS AFTERNOON.

* MEDIUM CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE AREA THIS AFTERNOON.

* LOW CONFIDENCE IN ISOLATED TS IMPACTING THE TERMINALS THIS AFTERNOON.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT...VFR.

THURSDAY THROUGH SATURDAY...PREDOMINANTLY VFR...WITH A CHANCE OF
TSRA IN MAINLY THE AFTERNOON & EARLY EVENING.

SUNDAY...VFR.

MONDAY...SCHC TSRA.

JEE

&&

.MARINE...
210 PM CDT

HIGH PRESSURE IN THE NORTHERN AND CENTRAL PLAINS IS EXPECTED TO
WEAKEN SOME OVER THE COMING DAYS BUT GENERALLY REMAIN STATIONARY FOR
MOST OF THE WEEK AS AN UPPER LEVEL LOW PRESSURE SYSTEMS REMAINS
PARKED OVER JAMES BAY THROUGH SATURDAY. IN THIS PATTERN WEAK LOW
PRESSURE SYSTEMS WILL GLIDE SOUTHEAST DOWN THE LAKE AT TIMES...WITH
THE FIRST EXPECTED LATER TONIGHT INTO EARLY WEDNESDAY.

IN THIS STAGNANT PATTERN THE PRESSURE GRADIENT WILL REMAIN ON THE
LIGHTER SIDE AND WILL PROMOTE THE DEVELOPMENT OF LAKE BREEZES FOR
THE NEARSHORE WATERS AND VARIABLE WINDS OVER MUCH OF THE OPEN LAKE
AND WINDS GENERALLY 15 KT OR LESS.  KMD

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 291959
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
259 PM CDT TUE JUL 29 2014

.DISCUSSION...
218 PM CDT

FORECAST ISSUES CONTINUE TO FOCUS ON DAILY DIURNAL ISOLATED TO
SCATTERED SHOWER/THUNDERSTORM CHANCES...WITH VERY GRADUAL WARM UP IN
TEMPERATURES THROUGH THE FORECAST PERIOD AS LONG WAVE UPPER TROUGH
OVER EASTERN NORTH AMERICA EFFECTIVELY RETROGRADES THROUGH THE END
OF THE WEEK BEFORE FINALLY WEAKENING AND PROGRESSING OFF TO THE
NORTHEAST BY LATE WEEKEND AND EARLY NEXT WEEK.

WESTERN GREAT LAKES REGION REMAINS IN WESTERN PERIPHERY OF THIS
AFOREMENTIONED TROUGH...WITHIN REGION OF BROAD CYCLONIC CIRCULATION.
SERIES OF RELATIVELY MINOR SHORT WAVES WILL CONTINUE TO RIPPLE
SOUTH-SOUTHEAST THROUGH THE FLOW ACROSS THE AREA THROUGH THE
REMAINDER OF THE WEEK. GOES WATER VAPOR IMAGERY INDICATES A COUPLE
OF WEAK RIPPLES PASSED ACROSS THE REGION THIS MORNING...WITH A
SOMEWHAT MORE ROBUST SHORT WAVE NOTED UPSTREAM PROPAGATING SOUTH
ACROSS WESTERN ONTARIO. THESE SYSTEMS WILL TEND TO MODULATE
MID-LEVEL TEMPS AND INSTABILITY...ESPECIALLY WHEN JUXTAPOSED ATOP
AFTERNOON/EARLY EVENING DIURNAL WARMTH. FORECAST SOUNDINGS CONTINUE
TO INDICATE WEAK/SKINNY MLCAPES OF 200-300 J/KG THIS AFTERNOON...
WITH VISIBLE SATELLITE IMAGERY INDICATING CUMULUS CONGESTUS
DEVELOPMENT ALONG WEAK LOW LEVEL CONVERGENCE AXIS FROM NEAR ROCKFORD
TO THE SOUTHEAST SIDE OF CHICAGO/NORTHWEST INDIANA WHERE THE LAKE
BREEZE BOUNDARY WAS PROVIDING SOME ADDITIONAL CONVERGENCE.
CURRENT WEAK RADAR RETURNS EXPECTED TO CONTINUE TO SLOWLY GROW
THIS AFTERNOON THROUGH PEAK INSTABILITY...RESULTING IN ISOLATED TO
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. WANING
INSTABILITY AFTER SUNSET THIS EVENING WILL ALLOW A DECREASE IN
COVERAGE. SIMILAR TREND EXPECTED TOMORROW...THOUGH ONTARIO SHORT
WAVE LOOKS TO MOVE ACROSS AREA DURING THE MORNING...AS OPPOSED TO
DURING PERIOD OF BETTER INSTABILITY LATER IN THE DAY. THIS MAY
FAVOR SOUTHEAST PARTS OF THE CWA WHERE FORCING WILL DECREASE
LAST...WHILE DAYTIME INSTABILITY DEVELOPS. THESE DIURNAL
SHOWERS/ISOLATED THUNDERSTORMS...TIED TO CONVERGENCE ZONES AS IS
THE CASE TODAY...WILL CONTINUE IN SIMILAR FASHION THURSDAY AS
WELL. OBVIOUSLY...NOT ALL AREAS WILL SEE PRECIP AND THERE WILL BE
MANY DRY HOURS EVEN IN PLACES THAT DO. BY FRIDAY...ADDITIONAL
SHORT WAVE ENERGY WILL DROP INTO THE WESTERN PORTION OF THE TROUGH
FROM THE NORTHERN PLAINS AND WILL EFFECTIVELY RETROGRADE THE LONG
WAVE TROUGH AXIS WESTWARD INTO THE WESTERN LAKES AND
MISSISSIPPI/LOWER OHIO VALLEY AREA. LARGE SCALE HEIGHT FALLS WILL
LEAD TO SLIGHTLY COOLER MID-LEVEL TEMPS WHICH MAY SUPPORT GREATER
COVERAGE IN SHOWERS/THUNDERSTORMS FRIDAY AND SATURDAY BEFORE THE
TROUGH AXIS BECOMES MORE PROGRESSIVE AND MOVES OFF TO THE EAST
SATURDAY NIGHT AND SUNDAY. THUS HAVE MAINTAINED SOMEWHAT HIGHER
CHANCE POPS WITH A GREATER AERIAL COVERAGE FOR THOSE DAYTIME
PERIODS.

SURFACE HIGH PRESSURE THEN BUILDS ACROSS THE AREA SUNDAY...BEFORE
DRIFTING TO THE SOUTHEAST MONDAY AS ANOTHER SHORT WAVE TROUGH
APPROACHES IN NORTHWEST FLOW ALOFT. THIS MID-LEVEL WAVE IS
ACCOMPANIED BY A SURFACE LOW AND COLD FRONT...WHICH RETURNS THE
SHOWER/THUNDERSTORM THREAT FOR MONDAY/TUESDAY OF NEXT WEEK.

AS FOR TEMPS...MID AND UPPER 70S BEING REACHED THIS AFTERNOON WITH
CONSIDERABLE SUNSHINE. MID-LEVEL TEMPS CONTINUE TO MODERATE VERY
SLOWLY THROUGH THE PERIOD...WITH TO SLOWLY WARMING FROM UPPER 70S TO
AROUND 80 TO LOWER 80S OUTSIDE OF LAKE BREEZE AND SHOWERS INTO THE
WEEKEND. COLD FRONTAL PASSAGE LATE MONDAY WILL ALLOW SUBTLE
COOL-DOWN FROM THE NORTH BY TUESDAY.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 20Z...

* LAKE BREEZE MAY IMPACT MDW LATER THIS AFTN WITH WINDS SHIFTING
  TO NE OR E BEHIND IT. BREEZE LOOKS TO STALL BEFORE REACHING
  ORD.

* ISOL TO SCT SHRA DEVELOP THIS AFTN INTO THE EARLY EVENING. MAY
  SEE A FEW THUNDERSTORMS AS WELL.

* LAKE BREEZE POSSIBLE AGAIN ON WEDNESDAY AFTERNOON.

KJB

//DISCUSSION...UPDATED 18Z...

OBSERVATIONS NEAR THE SHORES OF LAKE MICHIGAN ARE SHOWING SIGNS OF A
LAKE BREEZE DEVELOPING. THIS BOUNDARY WILL LIKELY PUSH INLAND A
LITTLE THIS AFTERNOON...IMPACTING KGYY AND POSSIBLY KMDW LATER IN
THE AFTERNOON. HOWEVER...I HAVE SOME DOUBTS THAT IT WILL MAKE IT TO
MDW GIVEN THE 12-15 KT OF 925 MB WEST-NORTHWESTERLY FLOW THAT IT
WILL BE WORKING AGAINST. FOR NOW...I WILL CONTINUE TO MONITOR THE
TRENDS OF THIS LAKE BREEZE AND MAKE A DECISION LATER OF WHETHER OR
NOT TO REMOVE THE WIND SHIFT FROM THE MDW TAF.

OTHERWISE...THE OTHER CONCERN LATER THIS AFTERNOON AND EVENING IS
THE THREAT FOR SCATTERED SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE
AREA. IT STILL APPEARS THE BEST TIMING FOR ANY ACTIVITY WOULD BE
AFTER 21 UTC THROUGH AROUND 02 UTC THIS EVENING. DUE TO THE
SCATTERED NATURE EXPECTED...I HAVE CONTINUED TO HANDLE THIS CHANCE
WITH A VCSH.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 20Z...

* HIGH CONFIDENECE WILL LAKE BREEZE GETTING TO MDW BY 21 UTC. LOW
  CONFIDENCE IN LAKE BREEZE IMPACTING ORD THIS AFTERNOON.

* MEDIUM CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE AREA THIS AFTERNOON.

* LOW CONFIDENCE IN ISOLATED TS IMPACTING THE TERMINALS THIS AFTERNOON.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT...VFR.

THURSDAY THROUGH SATURDAY...PREDOMINANTLY VFR...WITH A CHANCE OF
TSRA IN MAINLY THE AFTERNOON & EARLY EVENING.

SUNDAY...VFR.

MONDAY...SCHC TSRA.

JEE

&&

.MARINE...
210 PM CDT

HIGH PRESSURE IN THE NORTHERN AND CENTRAL PLAINS IS EXPECTED TO
WEAKEN SOME OVER THE COMING DAYS BUT GENERALLY REMAIN STATIONARY FOR
MOST OF THE WEEK AS AN UPPER LEVEL LOW PRESSURE SYSTEMS REMAINS
PARKED OVER JAMES BAY THROUGH SATURDAY. IN THIS PATTERN WEAK LOW
PRESSURE SYSTEMS WILL GLIDE SOUTHEAST DOWN THE LAKE AT TIMES...WITH
THE FIRST EXPECTED LATER TONIGHT INTO EARLY WEDNESDAY.

IN THIS STAGNANT PATTERN THE PRESSURE GRADIENT WILL REMAIN ON THE
LIGHTER SIDE AND WILL PROMOTE THE DEVELOPMENT OF LAKE BREEZES FOR
THE NEARSHORE WATERS AND VARIABLE WINDS OVER MUCH OF THE OPEN LAKE
AND WINDS GENERALLY 15 KT OR LESS.  KMD

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KILX 291930
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
230 PM CDT Tue Jul 29 2014

.DISCUSSION...
ISSUED 230 PM CDT Tue Jul 29 2014

Latest radar mosaics showing isolated showers and thunderstorms
from near Rockford southeast into central Indiana, along a weak
convergence boundary. HRRR suggests some of this may clip the far
northeast CWA later this afternoon, where 20% PoP`s remain in
place. Am planning on leaving the evening dry, as any lingering
showers will quickly be fizzling as sunset approaches.

Upper air analysis continues to show strong ridging west of the
Rockies northward into Canada, with the eastern states and
provinces dominated by a broad long wave trough anchored via an
upper low spinning north of the Great Lakes. The long range
pattern does not change during the forecast period, except that
the upper low opens up some and starts to lift northeast. Some
hints exist that it may return early next week, but the associated
cooler surge looks to stay north of Illinois at this point.

Little change in the going forecast is needed. Temperatures are
expected to rise a couple degrees, with lower 80s for highs and
upper 50s-lower 60s for lows from Wednesday through the weekend,
and slightly warmer early next week. Precipitation chances remain
focused on Friday and Saturday, mainly diurnally driven, as weak
shortwaves pivot through in the broader upper troughs.

Geelhart

&&

.AVIATION...
ISSUED 1254 PM CDT Tue Jul 29 2014

VFR conditions will prevail through the entire 18z TAF period.
Northwesterly winds of around 10kt this afternoon will diminish to
less than 5kt this evening as high pressure builds into the area.
Light W/NW winds will resume on Wednesday. Aside from SCT diurnal
clouds, skies will remain mostly clear through 18z Wed.

Barnes

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$







000
FXUS63 KILX 291930
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
230 PM CDT Tue Jul 29 2014

.DISCUSSION...
ISSUED 230 PM CDT Tue Jul 29 2014

Latest radar mosaics showing isolated showers and thunderstorms
from near Rockford southeast into central Indiana, along a weak
convergence boundary. HRRR suggests some of this may clip the far
northeast CWA later this afternoon, where 20% PoP`s remain in
place. Am planning on leaving the evening dry, as any lingering
showers will quickly be fizzling as sunset approaches.

Upper air analysis continues to show strong ridging west of the
Rockies northward into Canada, with the eastern states and
provinces dominated by a broad long wave trough anchored via an
upper low spinning north of the Great Lakes. The long range
pattern does not change during the forecast period, except that
the upper low opens up some and starts to lift northeast. Some
hints exist that it may return early next week, but the associated
cooler surge looks to stay north of Illinois at this point.

Little change in the going forecast is needed. Temperatures are
expected to rise a couple degrees, with lower 80s for highs and
upper 50s-lower 60s for lows from Wednesday through the weekend,
and slightly warmer early next week. Precipitation chances remain
focused on Friday and Saturday, mainly diurnally driven, as weak
shortwaves pivot through in the broader upper troughs.

Geelhart

&&

.AVIATION...
ISSUED 1254 PM CDT Tue Jul 29 2014

VFR conditions will prevail through the entire 18z TAF period.
Northwesterly winds of around 10kt this afternoon will diminish to
less than 5kt this evening as high pressure builds into the area.
Light W/NW winds will resume on Wednesday. Aside from SCT diurnal
clouds, skies will remain mostly clear through 18z Wed.

Barnes

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 291919
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
219 PM CDT TUE JUL 29 2014

.DISCUSSION...
218 PM CDT

FORECAST ISSUES CONTINUE TO FOCUS ON DAILY DIURNAL ISOLATED TO
SCATTERED SHOWER/THUNDERSTORM CHANCES...WITH VERY GRADUAL WARM UP IN
TEMPERATURES THROUGH THE FORECAST PERIOD AS LONG WAVE UPPER TROUGH
OVER EASTERN NORTH AMERICA EFFECTIVELY RETROGRADES THROUGH THE END
OF THE WEEK BEFORE FINALLY WEAKENING AND PROGRESSING OFF TO THE
NORTHEAST BY LATE WEEKEND AND EARLY NEXT WEEK.

WESTERN GREAT LAKES REGION REMAINS IN WESTERN PERIPHERY OF THIS
AFOREMENTIONED TROUGH...WITHIN REGION OF BROAD CYCLONIC CIRCULATION.
SERIES OF RELATIVELY MINOR SHORT WAVES WILL CONTINUE TO RIPPLE
SOUTH-SOUTHEAST THROUGH THE FLOW ACROSS THE AREA THROUGH THE
REMAINDER OF THE WEEK. GOES WATER VAPOR IMAGERY INDICATES A COUPLE
OF WEAK RIPPLES PASSED ACROSS THE REGION THIS MORNING...WITH A
SOMEWHAT MORE ROBUST SHORT WAVE NOTED UPSTREAM PROPAGATING SOUTH
ACROSS WESTERN ONTARIO. THESE SYSTEMS WILL TEND TO MODULATE
MID-LEVEL TEMPS AND INSTABILITY...ESPECIALLY WHEN JUXTAPOSED ATOP
AFTERNOON/EARLY EVENING DIURNAL WARMTH. FORECAST SOUNDINGS CONTINUE
TO INDICATE WEAK/SKINNY MLCAPES OF 200-300 J/KG THIS AFTERNOON...
WITH VISIBLE SATELLITE IMAGERY INDICATING CUMULUS CONGESTUS
DEVELOPMENT ALONG WEAK LOW LEVEL CONVERGENCE AXIS FROM NEAR ROCKFORD
TO THE SOUTHEAST SIDE OF CHICAGO/NORTHWEST INDIANA WHERE THE LAKE
BREEZE BOUNDARY WAS PROVIDING SOME ADDITIONAL CONVERGENCE.
CURRENT WEAK RADAR RETURNS EXPECTED TO CONTINUE TO SLOWLY GROW
THIS AFTERNOON THROUGH PEAK INSTABILITY...RESULTING IN ISOLATED TO
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. WANING
INSTABILITY AFTER SUNSET THIS EVENING WILL ALLOW A DECREASE IN
COVERAGE. SIMILAR TREND EXPECTED TOMORROW...THOUGH ONTARIO SHORT
WAVE LOOKS TO MOVE ACROSS AREA DURING THE MORNING...AS OPPOSED TO
DURING PERIOD OF BETTER INSTABILITY LATER IN THE DAY. THIS MAY
FAVOR SOUTHEAST PARTS OF THE CWA WHERE FORCING WILL DECREASE
LAST...WHILE DAYTIME INSTABILITY DEVELOPS. THESE DIURNAL
SHOWERS/ISOLATED THUNDERSTORMS...TIED TO CONVERGENCE ZONES AS IS
THE CASE TODAY...WILL CONTINUE IN SIMILAR FASHION THURSDAY AS
WELL. OBVIOUSLY...NOT ALL AREAS WILL SEE PRECIP AND THERE WILL BE
MANY DRY HOURS EVEN IN PLACES THAT DO. BY FRIDAY...ADDITIONAL
SHORT WAVE ENERGY WILL DROP INTO THE WESTERN PORTION OF THE TROUGH
FROM THE NORTHERN PLAINS AND WILL EFFECTIVELY RETROGRADE THE LONG
WAVE TROUGH AXIS WESTWARD INTO THE WESTERN LAKES AND
MISSISSIPPI/LOWER OHIO VALLEY AREA. LARGE SCALE HEIGHT FALLS WILL
LEAD TO SLIGHTLY COOLER MID-LEVEL TEMPS WHICH MAY SUPPORT GREATER
COVERAGE IN SHOWERS/THUNDERSTORMS FRIDAY AND SATURDAY BEFORE THE
TROUGH AXIS BECOMES MORE PROGRESSIVE AND MOVES OFF TO THE EAST
SATURDAY NIGHT AND SUNDAY. THUS HAVE MAINTAINED SOMEWHAT HIGHER
CHANCE POPS WITH A GREATER AERIAL COVERAGE FOR THOSE DAYTIME
PERIODS.

SURFACE HIGH PRESSURE THEN BUILDS ACROSS THE AREA SUNDAY...BEFORE
DRIFTING TO THE SOUTHEAST MONDAY AS ANOTHER SHORT WAVE TROUGH
APPROACHES IN NORTHWEST FLOW ALOFT. THIS MID-LEVEL WAVE IS
ACCOMPANIED BY A SURFACE LOW AND COLD FRONT...WHICH RETURNS THE
SHOWER/THUNDERSTORM THREAT FOR MONDAY/TUESDAY OF NEXT WEEK.

AS FOR TEMPS...MID AND UPPER 70S BEING REACHED THIS AFTERNOON WITH
CONSIDERABLE SUNSHINE. MID-LEVEL TEMPS CONTINUE TO MODERATE VERY
SLOWLY THROUGH THE PERIOD...WITH TO SLOWLY WARMING FROM UPPER 70S TO
AROUND 80 TO LOWER 80S OUTSIDE OF LAKE BREEZE AND SHOWERS INTO THE
WEEKEND. COLD FRONTAL PASSAGE LATE MONDAY WILL ALLOW SUBTLE
COOL-DOWN FROM THE NORTH BY TUESDAY.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* LAKE BREEZE MAY IMPACT MDW LATER THIS AFTN WITH WINDS SHIFTING
  TO NE OR E BEHIND IT. BREEZE SHOULD STALL BEFORE REACHING ORD.

* ISOL TO SCT SHRA DEVELOP THIS AFTN INTO THE EARLY EVENING. MAY
  SEE A FEW THUNDERSTORMS AS WELL.

* LAKE BREEZE POSSIBLE AGAIN ON WEDNESDAY AFTERNOON.

KJB

//DISCUSSION...UPDATED 18Z...

OBSERVATIONS NEAR THE SHORES OF LAKE MICHIGAN ARE SHOWING SIGNS OF A
LAKE BREEZE DEVELOPING. THIS BOUNDARY WILL LIKELY PUSH INLAND A
LITTLE THIS AFTERNOON...IMPACTING KGYY AND POSSIBLY KMDW LATER IN
THE AFTERNOON. HOWEVER...I HAVE SOME DOUBTS THAT IT WILL MAKE IT TO
MDW GIVEN THE 12-15 KT OF 925 MB WEST-NORTHWESTERLY FLOW THAT IT
WILL BE WORKING AGAINST. FOR NOW...I WILL CONTINUE TO MONITOR THE
TRENDS OF THIS LAKE BREEZE AND MAKE A DECISION LATER OF WHETHER OR
NOT TO REMOVE THE WIND SHIFT FROM THE MDW TAF.

OTHERWISE...THE OTHER CONCERN LATER THIS AFTERNOON AND EVENING IS
THE THREAT FOR SCATTERED SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE
AREA. IT STILL APPEARS THE BEST TIMING FOR ANY ACTIVITY WOULD BE
AFTER 21 UTC THROUGH AROUND 02 UTC THIS EVENING. DUE TO THE
SCATTERED NATURE EXPECTED...I HAVE CONTINUED TO HANDLE THIS CHANCE
WITH A VCSH.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* LOW CONFIDENCE IN LAKE BREEZE IMPACTING THE TERMINALS LATER
  THIS AFTERNOON.

* MEDIUM CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE AREA THIS AFTERNOON.

* LOW CONFIDENCE IN ISOLATED TS IMPACTING THE TERMINALS THIS AFTERNOON.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT...VFR.

THURSDAY THROUGH SATURDAY...PREDOMINANTLY VFR...WITH A CHANCE OF
TSRA IN MAINLY THE AFTERNOON & EARLY EVENING.

SUNDAY...VFR.

MONDAY...SCHC TSRA.

JEE

&&

.MARINE...
210 PM CDT

HIGH PRESSURE IN THE NORTHERN AND CENTRAL PLAINS IS EXPECTED TO
WEAKEN SOME OVER THE COMING DAYS BUT GENERALLY REMAIN STATIONARY FOR
MOST OF THE WEEK AS AN UPPER LEVEL LOW PRESSURE SYSTEMS REMAINS
PARKED OVER JAMES BAY THROUGH SATURDAY. IN THIS PATTERN WEAK LOW
PRESSURE SYSTEMS WILL GLIDE SOUTHEAST DOWN THE LAKE AT TIMES...WITH
THE FIRST EXPECTED LATER TONIGHT INTO EARLY WEDNESDAY.

IN THIS STAGNANT PATTERN THE PRESSURE GRADIENT WILL REMAIN ON THE
LIGHTER SIDE AND WILL PROMOTE THE DEVELOPMENT OF LAKE BREEZES FOR
THE NEARSHORE WATERS AND VARIABLE WINDS OVER MUCH OF THE OPEN LAKE
AND WINDS GENERALLY 15 KT OR LESS.  KMD

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 291919
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
219 PM CDT TUE JUL 29 2014

.DISCUSSION...
218 PM CDT

FORECAST ISSUES CONTINUE TO FOCUS ON DAILY DIURNAL ISOLATED TO
SCATTERED SHOWER/THUNDERSTORM CHANCES...WITH VERY GRADUAL WARM UP IN
TEMPERATURES THROUGH THE FORECAST PERIOD AS LONG WAVE UPPER TROUGH
OVER EASTERN NORTH AMERICA EFFECTIVELY RETROGRADES THROUGH THE END
OF THE WEEK BEFORE FINALLY WEAKENING AND PROGRESSING OFF TO THE
NORTHEAST BY LATE WEEKEND AND EARLY NEXT WEEK.

WESTERN GREAT LAKES REGION REMAINS IN WESTERN PERIPHERY OF THIS
AFOREMENTIONED TROUGH...WITHIN REGION OF BROAD CYCLONIC CIRCULATION.
SERIES OF RELATIVELY MINOR SHORT WAVES WILL CONTINUE TO RIPPLE
SOUTH-SOUTHEAST THROUGH THE FLOW ACROSS THE AREA THROUGH THE
REMAINDER OF THE WEEK. GOES WATER VAPOR IMAGERY INDICATES A COUPLE
OF WEAK RIPPLES PASSED ACROSS THE REGION THIS MORNING...WITH A
SOMEWHAT MORE ROBUST SHORT WAVE NOTED UPSTREAM PROPAGATING SOUTH
ACROSS WESTERN ONTARIO. THESE SYSTEMS WILL TEND TO MODULATE
MID-LEVEL TEMPS AND INSTABILITY...ESPECIALLY WHEN JUXTAPOSED ATOP
AFTERNOON/EARLY EVENING DIURNAL WARMTH. FORECAST SOUNDINGS CONTINUE
TO INDICATE WEAK/SKINNY MLCAPES OF 200-300 J/KG THIS AFTERNOON...
WITH VISIBLE SATELLITE IMAGERY INDICATING CUMULUS CONGESTUS
DEVELOPMENT ALONG WEAK LOW LEVEL CONVERGENCE AXIS FROM NEAR ROCKFORD
TO THE SOUTHEAST SIDE OF CHICAGO/NORTHWEST INDIANA WHERE THE LAKE
BREEZE BOUNDARY WAS PROVIDING SOME ADDITIONAL CONVERGENCE.
CURRENT WEAK RADAR RETURNS EXPECTED TO CONTINUE TO SLOWLY GROW
THIS AFTERNOON THROUGH PEAK INSTABILITY...RESULTING IN ISOLATED TO
SCATTERED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. WANING
INSTABILITY AFTER SUNSET THIS EVENING WILL ALLOW A DECREASE IN
COVERAGE. SIMILAR TREND EXPECTED TOMORROW...THOUGH ONTARIO SHORT
WAVE LOOKS TO MOVE ACROSS AREA DURING THE MORNING...AS OPPOSED TO
DURING PERIOD OF BETTER INSTABILITY LATER IN THE DAY. THIS MAY
FAVOR SOUTHEAST PARTS OF THE CWA WHERE FORCING WILL DECREASE
LAST...WHILE DAYTIME INSTABILITY DEVELOPS. THESE DIURNAL
SHOWERS/ISOLATED THUNDERSTORMS...TIED TO CONVERGENCE ZONES AS IS
THE CASE TODAY...WILL CONTINUE IN SIMILAR FASHION THURSDAY AS
WELL. OBVIOUSLY...NOT ALL AREAS WILL SEE PRECIP AND THERE WILL BE
MANY DRY HOURS EVEN IN PLACES THAT DO. BY FRIDAY...ADDITIONAL
SHORT WAVE ENERGY WILL DROP INTO THE WESTERN PORTION OF THE TROUGH
FROM THE NORTHERN PLAINS AND WILL EFFECTIVELY RETROGRADE THE LONG
WAVE TROUGH AXIS WESTWARD INTO THE WESTERN LAKES AND
MISSISSIPPI/LOWER OHIO VALLEY AREA. LARGE SCALE HEIGHT FALLS WILL
LEAD TO SLIGHTLY COOLER MID-LEVEL TEMPS WHICH MAY SUPPORT GREATER
COVERAGE IN SHOWERS/THUNDERSTORMS FRIDAY AND SATURDAY BEFORE THE
TROUGH AXIS BECOMES MORE PROGRESSIVE AND MOVES OFF TO THE EAST
SATURDAY NIGHT AND SUNDAY. THUS HAVE MAINTAINED SOMEWHAT HIGHER
CHANCE POPS WITH A GREATER AERIAL COVERAGE FOR THOSE DAYTIME
PERIODS.

SURFACE HIGH PRESSURE THEN BUILDS ACROSS THE AREA SUNDAY...BEFORE
DRIFTING TO THE SOUTHEAST MONDAY AS ANOTHER SHORT WAVE TROUGH
APPROACHES IN NORTHWEST FLOW ALOFT. THIS MID-LEVEL WAVE IS
ACCOMPANIED BY A SURFACE LOW AND COLD FRONT...WHICH RETURNS THE
SHOWER/THUNDERSTORM THREAT FOR MONDAY/TUESDAY OF NEXT WEEK.

AS FOR TEMPS...MID AND UPPER 70S BEING REACHED THIS AFTERNOON WITH
CONSIDERABLE SUNSHINE. MID-LEVEL TEMPS CONTINUE TO MODERATE VERY
SLOWLY THROUGH THE PERIOD...WITH TO SLOWLY WARMING FROM UPPER 70S TO
AROUND 80 TO LOWER 80S OUTSIDE OF LAKE BREEZE AND SHOWERS INTO THE
WEEKEND. COLD FRONTAL PASSAGE LATE MONDAY WILL ALLOW SUBTLE
COOL-DOWN FROM THE NORTH BY TUESDAY.

RATZER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* LAKE BREEZE MAY IMPACT MDW LATER THIS AFTN WITH WINDS SHIFTING
  TO NE OR E BEHIND IT. BREEZE SHOULD STALL BEFORE REACHING ORD.

* ISOL TO SCT SHRA DEVELOP THIS AFTN INTO THE EARLY EVENING. MAY
  SEE A FEW THUNDERSTORMS AS WELL.

* LAKE BREEZE POSSIBLE AGAIN ON WEDNESDAY AFTERNOON.

KJB

//DISCUSSION...UPDATED 18Z...

OBSERVATIONS NEAR THE SHORES OF LAKE MICHIGAN ARE SHOWING SIGNS OF A
LAKE BREEZE DEVELOPING. THIS BOUNDARY WILL LIKELY PUSH INLAND A
LITTLE THIS AFTERNOON...IMPACTING KGYY AND POSSIBLY KMDW LATER IN
THE AFTERNOON. HOWEVER...I HAVE SOME DOUBTS THAT IT WILL MAKE IT TO
MDW GIVEN THE 12-15 KT OF 925 MB WEST-NORTHWESTERLY FLOW THAT IT
WILL BE WORKING AGAINST. FOR NOW...I WILL CONTINUE TO MONITOR THE
TRENDS OF THIS LAKE BREEZE AND MAKE A DECISION LATER OF WHETHER OR
NOT TO REMOVE THE WIND SHIFT FROM THE MDW TAF.

OTHERWISE...THE OTHER CONCERN LATER THIS AFTERNOON AND EVENING IS
THE THREAT FOR SCATTERED SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE
AREA. IT STILL APPEARS THE BEST TIMING FOR ANY ACTIVITY WOULD BE
AFTER 21 UTC THROUGH AROUND 02 UTC THIS EVENING. DUE TO THE
SCATTERED NATURE EXPECTED...I HAVE CONTINUED TO HANDLE THIS CHANCE
WITH A VCSH.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* LOW CONFIDENCE IN LAKE BREEZE IMPACTING THE TERMINALS LATER
  THIS AFTERNOON.

* MEDIUM CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE AREA THIS AFTERNOON.

* LOW CONFIDENCE IN ISOLATED TS IMPACTING THE TERMINALS THIS AFTERNOON.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT...VFR.

THURSDAY THROUGH SATURDAY...PREDOMINANTLY VFR...WITH A CHANCE OF
TSRA IN MAINLY THE AFTERNOON & EARLY EVENING.

SUNDAY...VFR.

MONDAY...SCHC TSRA.

JEE

&&

.MARINE...
210 PM CDT

HIGH PRESSURE IN THE NORTHERN AND CENTRAL PLAINS IS EXPECTED TO
WEAKEN SOME OVER THE COMING DAYS BUT GENERALLY REMAIN STATIONARY FOR
MOST OF THE WEEK AS AN UPPER LEVEL LOW PRESSURE SYSTEMS REMAINS
PARKED OVER JAMES BAY THROUGH SATURDAY. IN THIS PATTERN WEAK LOW
PRESSURE SYSTEMS WILL GLIDE SOUTHEAST DOWN THE LAKE AT TIMES...WITH
THE FIRST EXPECTED LATER TONIGHT INTO EARLY WEDNESDAY.

IN THIS STAGNANT PATTERN THE PRESSURE GRADIENT WILL REMAIN ON THE
LIGHTER SIDE AND WILL PROMOTE THE DEVELOPMENT OF LAKE BREEZES FOR
THE NEARSHORE WATERS AND VARIABLE WINDS OVER MUCH OF THE OPEN LAKE
AND WINDS GENERALLY 15 KT OR LESS.  KMD

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO







000
FXUS63 KLOT 291912
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
212 PM CDT TUE JUL 29 2014

.DISCUSSION...
323 AM CDT

SYNOPSIS...BELOW NORMAL TEMPERATURES CONTINUE THIS WEEK WITH
TEMPERATURES EVER SO SLOWLY MODERATING. THERE IS A CHANCE FOR
AFTERNOON SHOWERS AND THUNDERSTORMS THROUGH SATURDAY WITH THE
BEST CHANCES OF SHOWERS TODAY AND THEN IT APPEARS AGAIN LATE IN
THE WEEK...FRIDAY OR POSSIBLY SATURDAY. WITH THE WINDS CONTINUING
TO EASE OVER THE LAKE...THE BEACH HAZARD STATEMENT WILL END AT
4AM CDT AS PLANNED.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS OVER JAMES BAY WHILE A SURFACE HIGH IS OVER
THE GREAT PLAINS. WITH A WEAK PRESSURE GRADIENT...WINDS WILL WILL
BE LIGHT THIS MORNING. THEY WILL PICK UP AS MIXING GETS GOING BUT
A LAKE BREEZE IS EXPECTED THIS AFTERNOON. HAVE MEDIUM CONFIDENCE
ON HOW FAR INLAND THE LAKE BREEZE PUSHES...BUT EXPECTING
TEMPERATURES TO FALL TO AROUND 70 BEHIND THE LAKE BREEZE. CANNOT
RULE OUT COOLING INTO THE 60S DUE TO UPWELLING OF COOLER LAKE MI
TEMPERATURES FROM THE RECENT STRONG NORTHERLY WINDS. ALL OTHER
LOCATIONS SHOULD SEE HIGHS IN THE MID TO UPPER 70S.

WE WILL HAVE MULTIPLE SOURCES OF FORCING TODAY BETWEEN THE LAKE
BREEZE AND AN UPPER LEVEL VORTICITY STREAMER SWINGING THROUGH THE
REGION. A FEW ISOLATED SHOWERS ARE CURRENTLY OVER CENTRAL WI AND
CENTRAL LAKE MICHIGAN AHEAD OF THAT WAVE. ALL AREAS HAVE A CHANCE
TO SEE ISOLATED TO SCATTERED SHOWERS THIS AFTERNOON. THE BEST
CHANCE AND COVERAGE WILL BE EAST OF A MCHENRY TO FOWLER INDIANA LINE
ALONG THE LAKE BREEZE. ALSO THINKING THE BEST CHANCE FOR
THUNDERSTORMS WILL BE ALONG THE LAKE BREEZE DUE TO THE ADDED
FORCING. THAT BEING SAID...ONLY EXPECTING ISOLATED THUNDERSTORMS
AS CAPE SHOULD BE LIMITED TODAY. MODELS SEEM TO BE OVER DOING
DEWPOINTS A BIT WHICH IS RESULTING IN OVER FORECASTED CAPE VALUES.
NO SEVERE STORMS ARE EXPECTED.

AN UPPER LEVEL WAVE AND COLD FRONT WILL PUSH SOUTH TONIGHT INTO
WEDNESDAY AND LOWS WILL BE IN THE UPPER 50S IN THE OUTLYING AREAS.
DOWNTOWN WILL HAVE A LOW IN THE LOWER 60S.

JEE

WEDNESDAY...
THE AFOREMENTIONED COLD FRONT LOOKS TO LOSE STEAM AS IT MOVES INTO
OUR SOUTHERN FORECAST AREA DUE TO THE UPPER WAVE AND SUPPORT
MOVING MORE EAST THAN SOUTH. THE SLOWER MOVEMENT WILL KEEP THIS
FOCUS...ALBEIT WEAK...IN THE EASTERN FORECAST AREA INTO THE
AFTERNOON. THAT AND ANOTHER LAKE BREEZE COULD PROVIDE FOR A
HANDFUL OF AFTERNOON SHOWERS/STORMS. AGAIN CHANCES ARE LIKELY NOT
AS HIGH AS SOME GUIDANCE IS INDICATING AND THAT LOOKS TO BE
ESPECIALLY TRUE NORTH AND WEST OF I-55. TEMPERATURES ARE EXPECTED
TO BE VERY SIMILAR TO TODAY.

THURSDAY THROUGH THE WEEKEND...
LITTLE PROGRESSION IN THE AMPLIFIED UPPER LEVEL PATTERN IS
FORECAST THROUGH SATURDAY. AS AN ILLUSTRATION OF THIS...FORECAST
SEA LEVEL PRESSURES RANGE FROM 1016MB TO 1019MB FROM THURSDAY
THROUGH SATURDAY NIGHT...I.E. NO CHANGE AND DAILY LAKE BREEZES.
THERE IS ONE FINAL UPPER LEVEL SHORT WAVE ON THE BACKSIDE OF THE
LONG WAVE TROUGH THAT HAS SURPRISINGLY GOOD CONSISTENCY ON THE
EC...GFS...AND GFS ENSEMBLE THAT COULD BRING HIGHER REGIONAL
COVERAGE TO AFTERNOON SHOWERS/STORMS ON FRI AND POSSIBLY ON SAT
DEPENDING ON FEATURE TIMING. ITS A PRETTY SUBTLE FEATURE TO KEY IN
ON AND WITH LITTLE IN THE WAY OF LOW-LEVEL FOCUS HAVE UNDERCUT
MODEL BLEND POPS WHICH ARE BIASED BY WHAT SEEMS TO BE A TOO WET
GFS. DRY WEATHER LOOKS TO OCCUR IN ITS WAKE WITH HIGHER CONFIDENCE
DURING THE LATTER HALF OF THE WEEKEND.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* LAKE BREEZE MAY IMPACT MDW LATER THIS AFTN WITH WINDS SHIFTING
  TO NE OR E BEHIND IT. BREEZE SHOULD STALL BEFORE REACHING ORD.

* ISOL TO SCT SHRA DEVELOP THIS AFTN INTO THE EARLY EVENING. MAY
  SEE A FEW THUNDERSTORMS AS WELL.

* LAKE BREEZE POSSIBLE AGAIN ON WEDNESDAY AFTERNOON.

KJB

//DISCUSSION...UPDATED 18Z...

OBSERVATIONS NEAR THE SHORES OF LAKE MICHIGAN ARE SHOWING SIGNS OF A
LAKE BREEZE DEVELOPING. THIS BOUNDARY WILL LIKELY PUSH INLAND A
LITTLE THIS AFTERNOON...IMPACTING KGYY AND POSSIBLY KMDW LATER IN
THE AFTERNOON. HOWEVER...I HAVE SOME DOUBTS THAT IT WILL MAKE IT TO
MDW GIVEN THE 12-15 KT OF 925 MB WEST-NORTHWESTERLY FLOW THAT IT
WILL BE WORKING AGAINST. FOR NOW...I WILL CONTINUE TO MONITOR THE
TRENDS OF THIS LAKE BREEZE AND MAKE A DECISION LATER OF WHETHER OR
NOT TO REMOVE THE WIND SHIFT FROM THE MDW TAF.

OTHERWISE...THE OTHER CONCERN LATER THIS AFTERNOON AND EVENING IS
THE THREAT FOR SCATTERED SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE
AREA. IT STILL APPEARS THE BEST TIMING FOR ANY ACTIVITY WOULD BE
AFTER 21 UTC THROUGH AROUND 02 UTC THIS EVENING. DUE TO THE
SCATTERED NATURE EXPECTED...I HAVE CONTINUED TO HANDLE THIS CHANCE
WITH A VCSH.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* LOW CONFIDENCE IN LAKE BREEZE IMPACTING THE TERMINALS LATER
  THIS AFTERNOON.

* MEDIUM CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE AREA THIS AFTERNOON.

* LOW CONFIDENCE IN ISOLATED TS IMPACTING THE TERMINALS THIS AFTERNOON.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT...VFR.

THURSDAY THROUGH SATURDAY...PREDOMINANTLY VFR...WITH A CHANCE OF
TSRA IN MAINLY THE AFTERNOON & EARLY EVENING.

SUNDAY...VFR.

MONDAY...SCHC TSRA.

JEE

&&

.MARINE...
210 PM CDT

HIGH PRESSURE IN THE NORTHERN AND CENTRAL PLAINS IS EXPECTED TO
WEAKEN SOME OVER THE COMING DAYS BUT GENERALLY REMAIN STATIONARY FOR
MOST OF THE WEEK AS AN UPPER LEVEL LOW PRESSURE SYSTEMS REMAINS
PARKED OVER JAMES BAY THROUGH SATURDAY. IN THIS PATTERN WEAK LOW
PRESSURE SYSTEMS WILL GLIDE SOUTHEAST DOWN THE LAKE AT TIMES...WITH
THE FIRST EXPECTED LATER TONIGHT INTO EARLY WEDNESDAY.

IN THIS STAGNANT PATTERN THE PRESSURE GRADIENT WILL REMAIN ON THE
LIGHTER SIDE AND WILL PROMOTE THE DEVELOPMENT OF LAKE BREEZES FOR
THE NEARSHORE WATERS AND VARIABLE WINDS OVER MUCH OF THE OPEN LAKE
AND WINDS GENERALLY 15 KT OR LESS.  KMD

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 291912
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
212 PM CDT TUE JUL 29 2014

.DISCUSSION...
323 AM CDT

SYNOPSIS...BELOW NORMAL TEMPERATURES CONTINUE THIS WEEK WITH
TEMPERATURES EVER SO SLOWLY MODERATING. THERE IS A CHANCE FOR
AFTERNOON SHOWERS AND THUNDERSTORMS THROUGH SATURDAY WITH THE
BEST CHANCES OF SHOWERS TODAY AND THEN IT APPEARS AGAIN LATE IN
THE WEEK...FRIDAY OR POSSIBLY SATURDAY. WITH THE WINDS CONTINUING
TO EASE OVER THE LAKE...THE BEACH HAZARD STATEMENT WILL END AT
4AM CDT AS PLANNED.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS OVER JAMES BAY WHILE A SURFACE HIGH IS OVER
THE GREAT PLAINS. WITH A WEAK PRESSURE GRADIENT...WINDS WILL WILL
BE LIGHT THIS MORNING. THEY WILL PICK UP AS MIXING GETS GOING BUT
A LAKE BREEZE IS EXPECTED THIS AFTERNOON. HAVE MEDIUM CONFIDENCE
ON HOW FAR INLAND THE LAKE BREEZE PUSHES...BUT EXPECTING
TEMPERATURES TO FALL TO AROUND 70 BEHIND THE LAKE BREEZE. CANNOT
RULE OUT COOLING INTO THE 60S DUE TO UPWELLING OF COOLER LAKE MI
TEMPERATURES FROM THE RECENT STRONG NORTHERLY WINDS. ALL OTHER
LOCATIONS SHOULD SEE HIGHS IN THE MID TO UPPER 70S.

WE WILL HAVE MULTIPLE SOURCES OF FORCING TODAY BETWEEN THE LAKE
BREEZE AND AN UPPER LEVEL VORTICITY STREAMER SWINGING THROUGH THE
REGION. A FEW ISOLATED SHOWERS ARE CURRENTLY OVER CENTRAL WI AND
CENTRAL LAKE MICHIGAN AHEAD OF THAT WAVE. ALL AREAS HAVE A CHANCE
TO SEE ISOLATED TO SCATTERED SHOWERS THIS AFTERNOON. THE BEST
CHANCE AND COVERAGE WILL BE EAST OF A MCHENRY TO FOWLER INDIANA LINE
ALONG THE LAKE BREEZE. ALSO THINKING THE BEST CHANCE FOR
THUNDERSTORMS WILL BE ALONG THE LAKE BREEZE DUE TO THE ADDED
FORCING. THAT BEING SAID...ONLY EXPECTING ISOLATED THUNDERSTORMS
AS CAPE SHOULD BE LIMITED TODAY. MODELS SEEM TO BE OVER DOING
DEWPOINTS A BIT WHICH IS RESULTING IN OVER FORECASTED CAPE VALUES.
NO SEVERE STORMS ARE EXPECTED.

AN UPPER LEVEL WAVE AND COLD FRONT WILL PUSH SOUTH TONIGHT INTO
WEDNESDAY AND LOWS WILL BE IN THE UPPER 50S IN THE OUTLYING AREAS.
DOWNTOWN WILL HAVE A LOW IN THE LOWER 60S.

JEE

WEDNESDAY...
THE AFOREMENTIONED COLD FRONT LOOKS TO LOSE STEAM AS IT MOVES INTO
OUR SOUTHERN FORECAST AREA DUE TO THE UPPER WAVE AND SUPPORT
MOVING MORE EAST THAN SOUTH. THE SLOWER MOVEMENT WILL KEEP THIS
FOCUS...ALBEIT WEAK...IN THE EASTERN FORECAST AREA INTO THE
AFTERNOON. THAT AND ANOTHER LAKE BREEZE COULD PROVIDE FOR A
HANDFUL OF AFTERNOON SHOWERS/STORMS. AGAIN CHANCES ARE LIKELY NOT
AS HIGH AS SOME GUIDANCE IS INDICATING AND THAT LOOKS TO BE
ESPECIALLY TRUE NORTH AND WEST OF I-55. TEMPERATURES ARE EXPECTED
TO BE VERY SIMILAR TO TODAY.

THURSDAY THROUGH THE WEEKEND...
LITTLE PROGRESSION IN THE AMPLIFIED UPPER LEVEL PATTERN IS
FORECAST THROUGH SATURDAY. AS AN ILLUSTRATION OF THIS...FORECAST
SEA LEVEL PRESSURES RANGE FROM 1016MB TO 1019MB FROM THURSDAY
THROUGH SATURDAY NIGHT...I.E. NO CHANGE AND DAILY LAKE BREEZES.
THERE IS ONE FINAL UPPER LEVEL SHORT WAVE ON THE BACKSIDE OF THE
LONG WAVE TROUGH THAT HAS SURPRISINGLY GOOD CONSISTENCY ON THE
EC...GFS...AND GFS ENSEMBLE THAT COULD BRING HIGHER REGIONAL
COVERAGE TO AFTERNOON SHOWERS/STORMS ON FRI AND POSSIBLY ON SAT
DEPENDING ON FEATURE TIMING. ITS A PRETTY SUBTLE FEATURE TO KEY IN
ON AND WITH LITTLE IN THE WAY OF LOW-LEVEL FOCUS HAVE UNDERCUT
MODEL BLEND POPS WHICH ARE BIASED BY WHAT SEEMS TO BE A TOO WET
GFS. DRY WEATHER LOOKS TO OCCUR IN ITS WAKE WITH HIGHER CONFIDENCE
DURING THE LATTER HALF OF THE WEEKEND.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* LAKE BREEZE MAY IMPACT MDW LATER THIS AFTN WITH WINDS SHIFTING
  TO NE OR E BEHIND IT. BREEZE SHOULD STALL BEFORE REACHING ORD.

* ISOL TO SCT SHRA DEVELOP THIS AFTN INTO THE EARLY EVENING. MAY
  SEE A FEW THUNDERSTORMS AS WELL.

* LAKE BREEZE POSSIBLE AGAIN ON WEDNESDAY AFTERNOON.

KJB

//DISCUSSION...UPDATED 18Z...

OBSERVATIONS NEAR THE SHORES OF LAKE MICHIGAN ARE SHOWING SIGNS OF A
LAKE BREEZE DEVELOPING. THIS BOUNDARY WILL LIKELY PUSH INLAND A
LITTLE THIS AFTERNOON...IMPACTING KGYY AND POSSIBLY KMDW LATER IN
THE AFTERNOON. HOWEVER...I HAVE SOME DOUBTS THAT IT WILL MAKE IT TO
MDW GIVEN THE 12-15 KT OF 925 MB WEST-NORTHWESTERLY FLOW THAT IT
WILL BE WORKING AGAINST. FOR NOW...I WILL CONTINUE TO MONITOR THE
TRENDS OF THIS LAKE BREEZE AND MAKE A DECISION LATER OF WHETHER OR
NOT TO REMOVE THE WIND SHIFT FROM THE MDW TAF.

OTHERWISE...THE OTHER CONCERN LATER THIS AFTERNOON AND EVENING IS
THE THREAT FOR SCATTERED SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE
AREA. IT STILL APPEARS THE BEST TIMING FOR ANY ACTIVITY WOULD BE
AFTER 21 UTC THROUGH AROUND 02 UTC THIS EVENING. DUE TO THE
SCATTERED NATURE EXPECTED...I HAVE CONTINUED TO HANDLE THIS CHANCE
WITH A VCSH.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* LOW CONFIDENCE IN LAKE BREEZE IMPACTING THE TERMINALS LATER
  THIS AFTERNOON.

* MEDIUM CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE AREA THIS AFTERNOON.

* LOW CONFIDENCE IN ISOLATED TS IMPACTING THE TERMINALS THIS AFTERNOON.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT...VFR.

THURSDAY THROUGH SATURDAY...PREDOMINANTLY VFR...WITH A CHANCE OF
TSRA IN MAINLY THE AFTERNOON & EARLY EVENING.

SUNDAY...VFR.

MONDAY...SCHC TSRA.

JEE

&&

.MARINE...
210 PM CDT

HIGH PRESSURE IN THE NORTHERN AND CENTRAL PLAINS IS EXPECTED TO
WEAKEN SOME OVER THE COMING DAYS BUT GENERALLY REMAIN STATIONARY FOR
MOST OF THE WEEK AS AN UPPER LEVEL LOW PRESSURE SYSTEMS REMAINS
PARKED OVER JAMES BAY THROUGH SATURDAY. IN THIS PATTERN WEAK LOW
PRESSURE SYSTEMS WILL GLIDE SOUTHEAST DOWN THE LAKE AT TIMES...WITH
THE FIRST EXPECTED LATER TONIGHT INTO EARLY WEDNESDAY.

IN THIS STAGNANT PATTERN THE PRESSURE GRADIENT WILL REMAIN ON THE
LIGHTER SIDE AND WILL PROMOTE THE DEVELOPMENT OF LAKE BREEZES FOR
THE NEARSHORE WATERS AND VARIABLE WINDS OVER MUCH OF THE OPEN LAKE
AND WINDS GENERALLY 15 KT OR LESS.  KMD

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 291912
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
212 PM CDT TUE JUL 29 2014

.DISCUSSION...
323 AM CDT

SYNOPSIS...BELOW NORMAL TEMPERATURES CONTINUE THIS WEEK WITH
TEMPERATURES EVER SO SLOWLY MODERATING. THERE IS A CHANCE FOR
AFTERNOON SHOWERS AND THUNDERSTORMS THROUGH SATURDAY WITH THE
BEST CHANCES OF SHOWERS TODAY AND THEN IT APPEARS AGAIN LATE IN
THE WEEK...FRIDAY OR POSSIBLY SATURDAY. WITH THE WINDS CONTINUING
TO EASE OVER THE LAKE...THE BEACH HAZARD STATEMENT WILL END AT
4AM CDT AS PLANNED.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS OVER JAMES BAY WHILE A SURFACE HIGH IS OVER
THE GREAT PLAINS. WITH A WEAK PRESSURE GRADIENT...WINDS WILL WILL
BE LIGHT THIS MORNING. THEY WILL PICK UP AS MIXING GETS GOING BUT
A LAKE BREEZE IS EXPECTED THIS AFTERNOON. HAVE MEDIUM CONFIDENCE
ON HOW FAR INLAND THE LAKE BREEZE PUSHES...BUT EXPECTING
TEMPERATURES TO FALL TO AROUND 70 BEHIND THE LAKE BREEZE. CANNOT
RULE OUT COOLING INTO THE 60S DUE TO UPWELLING OF COOLER LAKE MI
TEMPERATURES FROM THE RECENT STRONG NORTHERLY WINDS. ALL OTHER
LOCATIONS SHOULD SEE HIGHS IN THE MID TO UPPER 70S.

WE WILL HAVE MULTIPLE SOURCES OF FORCING TODAY BETWEEN THE LAKE
BREEZE AND AN UPPER LEVEL VORTICITY STREAMER SWINGING THROUGH THE
REGION. A FEW ISOLATED SHOWERS ARE CURRENTLY OVER CENTRAL WI AND
CENTRAL LAKE MICHIGAN AHEAD OF THAT WAVE. ALL AREAS HAVE A CHANCE
TO SEE ISOLATED TO SCATTERED SHOWERS THIS AFTERNOON. THE BEST
CHANCE AND COVERAGE WILL BE EAST OF A MCHENRY TO FOWLER INDIANA LINE
ALONG THE LAKE BREEZE. ALSO THINKING THE BEST CHANCE FOR
THUNDERSTORMS WILL BE ALONG THE LAKE BREEZE DUE TO THE ADDED
FORCING. THAT BEING SAID...ONLY EXPECTING ISOLATED THUNDERSTORMS
AS CAPE SHOULD BE LIMITED TODAY. MODELS SEEM TO BE OVER DOING
DEWPOINTS A BIT WHICH IS RESULTING IN OVER FORECASTED CAPE VALUES.
NO SEVERE STORMS ARE EXPECTED.

AN UPPER LEVEL WAVE AND COLD FRONT WILL PUSH SOUTH TONIGHT INTO
WEDNESDAY AND LOWS WILL BE IN THE UPPER 50S IN THE OUTLYING AREAS.
DOWNTOWN WILL HAVE A LOW IN THE LOWER 60S.

JEE

WEDNESDAY...
THE AFOREMENTIONED COLD FRONT LOOKS TO LOSE STEAM AS IT MOVES INTO
OUR SOUTHERN FORECAST AREA DUE TO THE UPPER WAVE AND SUPPORT
MOVING MORE EAST THAN SOUTH. THE SLOWER MOVEMENT WILL KEEP THIS
FOCUS...ALBEIT WEAK...IN THE EASTERN FORECAST AREA INTO THE
AFTERNOON. THAT AND ANOTHER LAKE BREEZE COULD PROVIDE FOR A
HANDFUL OF AFTERNOON SHOWERS/STORMS. AGAIN CHANCES ARE LIKELY NOT
AS HIGH AS SOME GUIDANCE IS INDICATING AND THAT LOOKS TO BE
ESPECIALLY TRUE NORTH AND WEST OF I-55. TEMPERATURES ARE EXPECTED
TO BE VERY SIMILAR TO TODAY.

THURSDAY THROUGH THE WEEKEND...
LITTLE PROGRESSION IN THE AMPLIFIED UPPER LEVEL PATTERN IS
FORECAST THROUGH SATURDAY. AS AN ILLUSTRATION OF THIS...FORECAST
SEA LEVEL PRESSURES RANGE FROM 1016MB TO 1019MB FROM THURSDAY
THROUGH SATURDAY NIGHT...I.E. NO CHANGE AND DAILY LAKE BREEZES.
THERE IS ONE FINAL UPPER LEVEL SHORT WAVE ON THE BACKSIDE OF THE
LONG WAVE TROUGH THAT HAS SURPRISINGLY GOOD CONSISTENCY ON THE
EC...GFS...AND GFS ENSEMBLE THAT COULD BRING HIGHER REGIONAL
COVERAGE TO AFTERNOON SHOWERS/STORMS ON FRI AND POSSIBLY ON SAT
DEPENDING ON FEATURE TIMING. ITS A PRETTY SUBTLE FEATURE TO KEY IN
ON AND WITH LITTLE IN THE WAY OF LOW-LEVEL FOCUS HAVE UNDERCUT
MODEL BLEND POPS WHICH ARE BIASED BY WHAT SEEMS TO BE A TOO WET
GFS. DRY WEATHER LOOKS TO OCCUR IN ITS WAKE WITH HIGHER CONFIDENCE
DURING THE LATTER HALF OF THE WEEKEND.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* LAKE BREEZE MAY IMPACT MDW LATER THIS AFTN WITH WINDS SHIFTING
  TO NE OR E BEHIND IT. BREEZE SHOULD STALL BEFORE REACHING ORD.

* ISOL TO SCT SHRA DEVELOP THIS AFTN INTO THE EARLY EVENING. MAY
  SEE A FEW THUNDERSTORMS AS WELL.

* LAKE BREEZE POSSIBLE AGAIN ON WEDNESDAY AFTERNOON.

KJB

//DISCUSSION...UPDATED 18Z...

OBSERVATIONS NEAR THE SHORES OF LAKE MICHIGAN ARE SHOWING SIGNS OF A
LAKE BREEZE DEVELOPING. THIS BOUNDARY WILL LIKELY PUSH INLAND A
LITTLE THIS AFTERNOON...IMPACTING KGYY AND POSSIBLY KMDW LATER IN
THE AFTERNOON. HOWEVER...I HAVE SOME DOUBTS THAT IT WILL MAKE IT TO
MDW GIVEN THE 12-15 KT OF 925 MB WEST-NORTHWESTERLY FLOW THAT IT
WILL BE WORKING AGAINST. FOR NOW...I WILL CONTINUE TO MONITOR THE
TRENDS OF THIS LAKE BREEZE AND MAKE A DECISION LATER OF WHETHER OR
NOT TO REMOVE THE WIND SHIFT FROM THE MDW TAF.

OTHERWISE...THE OTHER CONCERN LATER THIS AFTERNOON AND EVENING IS
THE THREAT FOR SCATTERED SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE
AREA. IT STILL APPEARS THE BEST TIMING FOR ANY ACTIVITY WOULD BE
AFTER 21 UTC THROUGH AROUND 02 UTC THIS EVENING. DUE TO THE
SCATTERED NATURE EXPECTED...I HAVE CONTINUED TO HANDLE THIS CHANCE
WITH A VCSH.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* LOW CONFIDENCE IN LAKE BREEZE IMPACTING THE TERMINALS LATER
  THIS AFTERNOON.

* MEDIUM CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE AREA THIS AFTERNOON.

* LOW CONFIDENCE IN ISOLATED TS IMPACTING THE TERMINALS THIS AFTERNOON.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT...VFR.

THURSDAY THROUGH SATURDAY...PREDOMINANTLY VFR...WITH A CHANCE OF
TSRA IN MAINLY THE AFTERNOON & EARLY EVENING.

SUNDAY...VFR.

MONDAY...SCHC TSRA.

JEE

&&

.MARINE...
210 PM CDT

HIGH PRESSURE IN THE NORTHERN AND CENTRAL PLAINS IS EXPECTED TO
WEAKEN SOME OVER THE COMING DAYS BUT GENERALLY REMAIN STATIONARY FOR
MOST OF THE WEEK AS AN UPPER LEVEL LOW PRESSURE SYSTEMS REMAINS
PARKED OVER JAMES BAY THROUGH SATURDAY. IN THIS PATTERN WEAK LOW
PRESSURE SYSTEMS WILL GLIDE SOUTHEAST DOWN THE LAKE AT TIMES...WITH
THE FIRST EXPECTED LATER TONIGHT INTO EARLY WEDNESDAY.

IN THIS STAGNANT PATTERN THE PRESSURE GRADIENT WILL REMAIN ON THE
LIGHTER SIDE AND WILL PROMOTE THE DEVELOPMENT OF LAKE BREEZES FOR
THE NEARSHORE WATERS AND VARIABLE WINDS OVER MUCH OF THE OPEN LAKE
AND WINDS GENERALLY 15 KT OR LESS.  KMD

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 291912
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
212 PM CDT TUE JUL 29 2014

.DISCUSSION...
323 AM CDT

SYNOPSIS...BELOW NORMAL TEMPERATURES CONTINUE THIS WEEK WITH
TEMPERATURES EVER SO SLOWLY MODERATING. THERE IS A CHANCE FOR
AFTERNOON SHOWERS AND THUNDERSTORMS THROUGH SATURDAY WITH THE
BEST CHANCES OF SHOWERS TODAY AND THEN IT APPEARS AGAIN LATE IN
THE WEEK...FRIDAY OR POSSIBLY SATURDAY. WITH THE WINDS CONTINUING
TO EASE OVER THE LAKE...THE BEACH HAZARD STATEMENT WILL END AT
4AM CDT AS PLANNED.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS OVER JAMES BAY WHILE A SURFACE HIGH IS OVER
THE GREAT PLAINS. WITH A WEAK PRESSURE GRADIENT...WINDS WILL WILL
BE LIGHT THIS MORNING. THEY WILL PICK UP AS MIXING GETS GOING BUT
A LAKE BREEZE IS EXPECTED THIS AFTERNOON. HAVE MEDIUM CONFIDENCE
ON HOW FAR INLAND THE LAKE BREEZE PUSHES...BUT EXPECTING
TEMPERATURES TO FALL TO AROUND 70 BEHIND THE LAKE BREEZE. CANNOT
RULE OUT COOLING INTO THE 60S DUE TO UPWELLING OF COOLER LAKE MI
TEMPERATURES FROM THE RECENT STRONG NORTHERLY WINDS. ALL OTHER
LOCATIONS SHOULD SEE HIGHS IN THE MID TO UPPER 70S.

WE WILL HAVE MULTIPLE SOURCES OF FORCING TODAY BETWEEN THE LAKE
BREEZE AND AN UPPER LEVEL VORTICITY STREAMER SWINGING THROUGH THE
REGION. A FEW ISOLATED SHOWERS ARE CURRENTLY OVER CENTRAL WI AND
CENTRAL LAKE MICHIGAN AHEAD OF THAT WAVE. ALL AREAS HAVE A CHANCE
TO SEE ISOLATED TO SCATTERED SHOWERS THIS AFTERNOON. THE BEST
CHANCE AND COVERAGE WILL BE EAST OF A MCHENRY TO FOWLER INDIANA LINE
ALONG THE LAKE BREEZE. ALSO THINKING THE BEST CHANCE FOR
THUNDERSTORMS WILL BE ALONG THE LAKE BREEZE DUE TO THE ADDED
FORCING. THAT BEING SAID...ONLY EXPECTING ISOLATED THUNDERSTORMS
AS CAPE SHOULD BE LIMITED TODAY. MODELS SEEM TO BE OVER DOING
DEWPOINTS A BIT WHICH IS RESULTING IN OVER FORECASTED CAPE VALUES.
NO SEVERE STORMS ARE EXPECTED.

AN UPPER LEVEL WAVE AND COLD FRONT WILL PUSH SOUTH TONIGHT INTO
WEDNESDAY AND LOWS WILL BE IN THE UPPER 50S IN THE OUTLYING AREAS.
DOWNTOWN WILL HAVE A LOW IN THE LOWER 60S.

JEE

WEDNESDAY...
THE AFOREMENTIONED COLD FRONT LOOKS TO LOSE STEAM AS IT MOVES INTO
OUR SOUTHERN FORECAST AREA DUE TO THE UPPER WAVE AND SUPPORT
MOVING MORE EAST THAN SOUTH. THE SLOWER MOVEMENT WILL KEEP THIS
FOCUS...ALBEIT WEAK...IN THE EASTERN FORECAST AREA INTO THE
AFTERNOON. THAT AND ANOTHER LAKE BREEZE COULD PROVIDE FOR A
HANDFUL OF AFTERNOON SHOWERS/STORMS. AGAIN CHANCES ARE LIKELY NOT
AS HIGH AS SOME GUIDANCE IS INDICATING AND THAT LOOKS TO BE
ESPECIALLY TRUE NORTH AND WEST OF I-55. TEMPERATURES ARE EXPECTED
TO BE VERY SIMILAR TO TODAY.

THURSDAY THROUGH THE WEEKEND...
LITTLE PROGRESSION IN THE AMPLIFIED UPPER LEVEL PATTERN IS
FORECAST THROUGH SATURDAY. AS AN ILLUSTRATION OF THIS...FORECAST
SEA LEVEL PRESSURES RANGE FROM 1016MB TO 1019MB FROM THURSDAY
THROUGH SATURDAY NIGHT...I.E. NO CHANGE AND DAILY LAKE BREEZES.
THERE IS ONE FINAL UPPER LEVEL SHORT WAVE ON THE BACKSIDE OF THE
LONG WAVE TROUGH THAT HAS SURPRISINGLY GOOD CONSISTENCY ON THE
EC...GFS...AND GFS ENSEMBLE THAT COULD BRING HIGHER REGIONAL
COVERAGE TO AFTERNOON SHOWERS/STORMS ON FRI AND POSSIBLY ON SAT
DEPENDING ON FEATURE TIMING. ITS A PRETTY SUBTLE FEATURE TO KEY IN
ON AND WITH LITTLE IN THE WAY OF LOW-LEVEL FOCUS HAVE UNDERCUT
MODEL BLEND POPS WHICH ARE BIASED BY WHAT SEEMS TO BE A TOO WET
GFS. DRY WEATHER LOOKS TO OCCUR IN ITS WAKE WITH HIGHER CONFIDENCE
DURING THE LATTER HALF OF THE WEEKEND.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* LAKE BREEZE MAY IMPACT MDW LATER THIS AFTN WITH WINDS SHIFTING
  TO NE OR E BEHIND IT. BREEZE SHOULD STALL BEFORE REACHING ORD.

* ISOL TO SCT SHRA DEVELOP THIS AFTN INTO THE EARLY EVENING. MAY
  SEE A FEW THUNDERSTORMS AS WELL.

* LAKE BREEZE POSSIBLE AGAIN ON WEDNESDAY AFTERNOON.

KJB

//DISCUSSION...UPDATED 18Z...

OBSERVATIONS NEAR THE SHORES OF LAKE MICHIGAN ARE SHOWING SIGNS OF A
LAKE BREEZE DEVELOPING. THIS BOUNDARY WILL LIKELY PUSH INLAND A
LITTLE THIS AFTERNOON...IMPACTING KGYY AND POSSIBLY KMDW LATER IN
THE AFTERNOON. HOWEVER...I HAVE SOME DOUBTS THAT IT WILL MAKE IT TO
MDW GIVEN THE 12-15 KT OF 925 MB WEST-NORTHWESTERLY FLOW THAT IT
WILL BE WORKING AGAINST. FOR NOW...I WILL CONTINUE TO MONITOR THE
TRENDS OF THIS LAKE BREEZE AND MAKE A DECISION LATER OF WHETHER OR
NOT TO REMOVE THE WIND SHIFT FROM THE MDW TAF.

OTHERWISE...THE OTHER CONCERN LATER THIS AFTERNOON AND EVENING IS
THE THREAT FOR SCATTERED SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE
AREA. IT STILL APPEARS THE BEST TIMING FOR ANY ACTIVITY WOULD BE
AFTER 21 UTC THROUGH AROUND 02 UTC THIS EVENING. DUE TO THE
SCATTERED NATURE EXPECTED...I HAVE CONTINUED TO HANDLE THIS CHANCE
WITH A VCSH.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* LOW CONFIDENCE IN LAKE BREEZE IMPACTING THE TERMINALS LATER
  THIS AFTERNOON.

* MEDIUM CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE AREA THIS AFTERNOON.

* LOW CONFIDENCE IN ISOLATED TS IMPACTING THE TERMINALS THIS AFTERNOON.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT...VFR.

THURSDAY THROUGH SATURDAY...PREDOMINANTLY VFR...WITH A CHANCE OF
TSRA IN MAINLY THE AFTERNOON & EARLY EVENING.

SUNDAY...VFR.

MONDAY...SCHC TSRA.

JEE

&&

.MARINE...
210 PM CDT

HIGH PRESSURE IN THE NORTHERN AND CENTRAL PLAINS IS EXPECTED TO
WEAKEN SOME OVER THE COMING DAYS BUT GENERALLY REMAIN STATIONARY FOR
MOST OF THE WEEK AS AN UPPER LEVEL LOW PRESSURE SYSTEMS REMAINS
PARKED OVER JAMES BAY THROUGH SATURDAY. IN THIS PATTERN WEAK LOW
PRESSURE SYSTEMS WILL GLIDE SOUTHEAST DOWN THE LAKE AT TIMES...WITH
THE FIRST EXPECTED LATER TONIGHT INTO EARLY WEDNESDAY.

IN THIS STAGNANT PATTERN THE PRESSURE GRADIENT WILL REMAIN ON THE
LIGHTER SIDE AND WILL PROMOTE THE DEVELOPMENT OF LAKE BREEZES FOR
THE NEARSHORE WATERS AND VARIABLE WINDS OVER MUCH OF THE OPEN LAKE
AND WINDS GENERALLY 15 KT OR LESS.  KMD

KMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KILX 291754
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1254 PM CDT Tue Jul 29 2014

.DISCUSSION...
ISSUED 1045 AM CDT Tue Jul 29 2014

Deep upper trough across the eastern CONUS continues to be the
dominant weather-maker across central Illinois today. Northerly
flow is providing unseasonably cool temperatures, with afternoon
highs once again expected to remain in the 70s. Main question will
be whether or not any showers will develop within the cyclonic
flow pattern aloft. Not really seeing much of anything on the
latest water vapor imagery, so am skeptical any showers will form
today. Will however hold on to just slight chance PoPs northeast
of I-74 as HRRR/NAM12 both develop a few showers across northeast
Illinois late this afternoon. No zone updated needed at this time.


Barnes
&&

.AVIATION...
ISSUED 1254 PM CDT Tue Jul 29 2014

VFR conditions will prevail through the entire 18z TAF period.
Northwesterly winds of around 10kt this afternoon will diminish to
less than 5kt this evening as high pressure builds into the area.
Light W/NW winds will resume on Wednesday. Aside from SCT diurnal
clouds, skies will remain mostly clear through 18z Wed.

Barnes
&&

.PREV DISCUSSION...
ISSUED 308 AM CDT Tue Jul 29 2014
Upper level ridge over the western half of the country, and trof
over the eastern half... putting much of the northern Plains and
the Midwest under northwesterly flow. This pattern sticks around
for the next few days, with weak flow under a building surface
high. Forecast dominated by slowly creeping up temperatures,
though remaining below normal, and afternoon instability showers.
Best chances for precip heading into the weekend, however, with
another wave on its way as well as a kicker to shift the pattern
aloft and move the trof out of the region by the end of the
weekend. Though models are consistent with the overall trend of
the pattern, the details on timing and extent of the afternoon
showers differs here and there...as well as the
timing/impact/strength of the Fri/Friday evening wave.

SHORT TERM...Today and tomorrow...
Each day a degree or two warmer than the previous day.
Northwesterly winds today as the high continues to build into the
region. Tomorrows winds a bit more west/northwesterly and somewhat
lighter. Rain chances today should remain limited to the
northwest. Though a few models are coming in dry...and the GFS the
other extreme with overblown convection... the more high res model
data output in the 4km wrf and the HRRR is showing some shower
activity to the NE. Wave diving into the trof visible on wv sat
imagery this morning will assist the diurnal afternoon development
and cannot completely rule out some isolated shower activity.
However, tomorrows afternoon showers access more instability in
the midlevels, albeit a small amount, and pops spread over much of
ILX tomorrow with the addition of thunder.

LONG TERM...Thursday through Monday...
Continued below normal temps and northwesterly flow through the
end of the week with some small impulses assisting the afternoon
showers.  Models continue to enhance this activity on Thursday
night and into Friday as the impulses start moving into the west
coast and trying to break down the ridging to the west. GFS far
more aggressive with the precip and the ECMWF is timing a little
quicker with the wave and missing the collision with the max
afternoon heating...and therefore much less qpf. Models beginning
to signal the progression of the deep trof out of the region for
late Sunday and into Monday...which would mean a return to warmer
conditions.

HJS


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$







000
FXUS63 KILX 291754
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1254 PM CDT Tue Jul 29 2014

.DISCUSSION...
ISSUED 1045 AM CDT Tue Jul 29 2014

Deep upper trough across the eastern CONUS continues to be the
dominant weather-maker across central Illinois today. Northerly
flow is providing unseasonably cool temperatures, with afternoon
highs once again expected to remain in the 70s. Main question will
be whether or not any showers will develop within the cyclonic
flow pattern aloft. Not really seeing much of anything on the
latest water vapor imagery, so am skeptical any showers will form
today. Will however hold on to just slight chance PoPs northeast
of I-74 as HRRR/NAM12 both develop a few showers across northeast
Illinois late this afternoon. No zone updated needed at this time.


Barnes
&&

.AVIATION...
ISSUED 1254 PM CDT Tue Jul 29 2014

VFR conditions will prevail through the entire 18z TAF period.
Northwesterly winds of around 10kt this afternoon will diminish to
less than 5kt this evening as high pressure builds into the area.
Light W/NW winds will resume on Wednesday. Aside from SCT diurnal
clouds, skies will remain mostly clear through 18z Wed.

Barnes
&&

.PREV DISCUSSION...
ISSUED 308 AM CDT Tue Jul 29 2014
Upper level ridge over the western half of the country, and trof
over the eastern half... putting much of the northern Plains and
the Midwest under northwesterly flow. This pattern sticks around
for the next few days, with weak flow under a building surface
high. Forecast dominated by slowly creeping up temperatures,
though remaining below normal, and afternoon instability showers.
Best chances for precip heading into the weekend, however, with
another wave on its way as well as a kicker to shift the pattern
aloft and move the trof out of the region by the end of the
weekend. Though models are consistent with the overall trend of
the pattern, the details on timing and extent of the afternoon
showers differs here and there...as well as the
timing/impact/strength of the Fri/Friday evening wave.

SHORT TERM...Today and tomorrow...
Each day a degree or two warmer than the previous day.
Northwesterly winds today as the high continues to build into the
region. Tomorrows winds a bit more west/northwesterly and somewhat
lighter. Rain chances today should remain limited to the
northwest. Though a few models are coming in dry...and the GFS the
other extreme with overblown convection... the more high res model
data output in the 4km wrf and the HRRR is showing some shower
activity to the NE. Wave diving into the trof visible on wv sat
imagery this morning will assist the diurnal afternoon development
and cannot completely rule out some isolated shower activity.
However, tomorrows afternoon showers access more instability in
the midlevels, albeit a small amount, and pops spread over much of
ILX tomorrow with the addition of thunder.

LONG TERM...Thursday through Monday...
Continued below normal temps and northwesterly flow through the
end of the week with some small impulses assisting the afternoon
showers.  Models continue to enhance this activity on Thursday
night and into Friday as the impulses start moving into the west
coast and trying to break down the ridging to the west. GFS far
more aggressive with the precip and the ECMWF is timing a little
quicker with the wave and missing the collision with the max
afternoon heating...and therefore much less qpf. Models beginning
to signal the progression of the deep trof out of the region for
late Sunday and into Monday...which would mean a return to warmer
conditions.

HJS


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 291713
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1213 PM CDT TUE JUL 29 2014

.DISCUSSION...
323 AM CDT

SYNOPSIS...BELOW NORMAL TEMPERATURES CONTINUE THIS WEEK WITH
TEMPERATURES EVER SO SLOWLY MODERATING. THERE IS A CHANCE FOR
AFTERNOON SHOWERS AND THUNDERSTORMS THROUGH SATURDAY WITH THE
BEST CHANCES OF SHOWERS TODAY AND THEN IT APPEARS AGAIN LATE IN
THE WEEK...FRIDAY OR POSSIBLY SATURDAY. WITH THE WINDS CONTINUING
TO EASE OVER THE LAKE...THE BEACH HAZARD STATEMENT WILL END AT
4AM CDT AS PLANNED.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS OVER JAMES BAY WHILE A SURFACE HIGH IS OVER
THE GREAT PLAINS. WITH A WEAK PRESSURE GRADIENT...WINDS WILL WILL
BE LIGHT THIS MORNING. THEY WILL PICK UP AS MIXING GETS GOING BUT
A LAKE BREEZE IS EXPECTED THIS AFTERNOON. HAVE MEDIUM CONFIDENCE
ON HOW FAR INLAND THE LAKE BREEZE PUSHES...BUT EXPECTING
TEMPERATURES TO FALL TO AROUND 70 BEHIND THE LAKE BREEZE. CANNOT
RULE OUT COOLING INTO THE 60S DUE TO UPWELLING OF COOLER LAKE MI
TEMPERATURES FROM THE RECENT STRONG NORTHERLY WINDS. ALL OTHER
LOCATIONS SHOULD SEE HIGHS IN THE MID TO UPPER 70S.

WE WILL HAVE MULTIPLE SOURCES OF FORCING TODAY BETWEEN THE LAKE
BREEZE AND AN UPPER LEVEL VORTICITY STREAMER SWINGING THROUGH THE
REGION. A FEW ISOLATED SHOWERS ARE CURRENTLY OVER CENTRAL WI AND
CENTRAL LAKE MICHIGAN AHEAD OF THAT WAVE. ALL AREAS HAVE A CHANCE
TO SEE ISOLATED TO SCATTERED SHOWERS THIS AFTERNOON. THE BEST
CHANCE AND COVERAGE WILL BE EAST OF A MCHENRY TO FOWLER INDIANA LINE
ALONG THE LAKE BREEZE. ALSO THINKING THE BEST CHANCE FOR
THUNDERSTORMS WILL BE ALONG THE LAKE BREEZE DUE TO THE ADDED
FORCING. THAT BEING SAID...ONLY EXPECTING ISOLATED THUNDERSTORMS
AS CAPE SHOULD BE LIMITED TODAY. MODELS SEEM TO BE OVER DOING
DEWPOINTS A BIT WHICH IS RESULTING IN OVER FORECASTED CAPE VALUES.
NO SEVERE STORMS ARE EXPECTED.

AN UPPER LEVEL WAVE AND COLD FRONT WILL PUSH SOUTH TONIGHT INTO
WEDNESDAY AND LOWS WILL BE IN THE UPPER 50S IN THE OUTLYING AREAS.
DOWNTOWN WILL HAVE A LOW IN THE LOWER 60S.

JEE

WEDNESDAY...
THE AFOREMENTIONED COLD FRONT LOOKS TO LOSE STEAM AS IT MOVES INTO
OUR SOUTHERN FORECAST AREA DUE TO THE UPPER WAVE AND SUPPORT
MOVING MORE EAST THAN SOUTH. THE SLOWER MOVEMENT WILL KEEP THIS
FOCUS...ALBEIT WEAK...IN THE EASTERN FORECAST AREA INTO THE
AFTERNOON. THAT AND ANOTHER LAKE BREEZE COULD PROVIDE FOR A
HANDFUL OF AFTERNOON SHOWERS/STORMS. AGAIN CHANCES ARE LIKELY NOT
AS HIGH AS SOME GUIDANCE IS INDICATING AND THAT LOOKS TO BE
ESPECIALLY TRUE NORTH AND WEST OF I-55. TEMPERATURES ARE EXPECTED
TO BE VERY SIMILAR TO TODAY.

THURSDAY THROUGH THE WEEKEND...
LITTLE PROGRESSION IN THE AMPLIFIED UPPER LEVEL PATTERN IS
FORECAST THROUGH SATURDAY. AS AN ILLUSTRATION OF THIS...FORECAST
SEA LEVEL PRESSURES RANGE FROM 1016MB TO 1019MB FROM THURSDAY
THROUGH SATURDAY NIGHT...I.E. NO CHANGE AND DAILY LAKE BREEZES.
THERE IS ONE FINAL UPPER LEVEL SHORT WAVE ON THE BACKSIDE OF THE
LONG WAVE TROUGH THAT HAS SURPRISINGLY GOOD CONSISTENCY ON THE
EC...GFS...AND GFS ENSEMBLE THAT COULD BRING HIGHER REGIONAL
COVERAGE TO AFTERNOON SHOWERS/STORMS ON FRI AND POSSIBLY ON SAT
DEPENDING ON FEATURE TIMING. ITS A PRETTY SUBTLE FEATURE TO KEY IN
ON AND WITH LITTLE IN THE WAY OF LOW-LEVEL FOCUS HAVE UNDERCUT
MODEL BLEND POPS WHICH ARE BIASED BY WHAT SEEMS TO BE A TOO WET
GFS. DRY WEATHER LOOKS TO OCCUR IN ITS WAKE WITH HIGHER CONFIDENCE
DURING THE LATTER HALF OF THE WEEKEND.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* LAKE BREEZE MAY IMPACT MDW LATER THIS AFTN WITH WINDS SHIFTING
  TO NE OR E BEHIND IT. BREEZE SHOULD STALL BEFORE REACHING ORD.

* ISOL TO SCT SHRA DEVELOP THIS AFTN INTO THE EARLY EVENING. MAY
  SEE A FEW THUNDERSTORMS AS WELL.

* LAKE BREEZE POSSIBLE AGAIN ON WEDNESDAY AFTERNOON.

KJB

//DISCUSSION...UPDATED 18Z...

OBSERVATIONS NEAR THE SHORES OF LAKE MICHIGAN ARE SHOWING SIGNS OF A
LAKE BREEZE DEVELOPING. THIS BOUNDARY WILL LIKELY PUSH INLAND A
LITTLE THIS AFTERNOON...IMPACTING KGYY AND POSSIBLY KMDW LATER IN
THE AFTERNOON. HOWEVER...I HAVE SOME DOUBTS THAT IT WILL MAKE IT TO
MDW GIVEN THE 12-15 KT OF 925 MB WEST-NORTHWESTERLY FLOW THAT IT
WILL BE WORKING AGAINST. FOR NOW...I WILL CONTINUE TO MONITOR THE
TRENDS OF THIS LAKE BREEZE AND MAKE A DECISION LATER OF WHETHER OR
NOT TO REMOVE THE WIND SHIFT FROM THE MDW TAF.

OTHERWISE...THE OTHER CONCERN LATER THIS AFTERNOON AND EVENING IS
THE THREAT FOR SCATTERED SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE
AREA. IT STILL APPEARS THE BEST TIMING FOR ANY ACTIVITY WOULD BE
AFTER 21 UTC THROUGH AROUND 02 UTC THIS EVENING. DUE TO THE
SCATTERED NATURE EXPECTED...I HAVE CONTINUED TO HANDLE THIS CHANCE
WITH A VCSH.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.



KJB


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* LOW CONFIDENCE IN LAKE BREEZE IMPACTING THE TERMINALS LATER
  THIS AFTERNOON.

* MEDIUM CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE AREA THIS AFTERNOON.

* LOW CONFIDENCE IN ISOLATED TS IMPACTING THE TERMINALS THIS AFTERNOON.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT...VFR.

THURSDAY THROUGH SATURDAY...PREDOMINANTLY VFR...WITH A CHANCE OF
TSRA IN MAINLY THE AFTERNOON & EARLY EVENING.

SUNDAY...VFR.

MONDAY...SCHC TSRA.

JEE

&&

.MARINE...
323 AM CDT

WILL END THE SMALL CRAFT ADVISORY AT 4AM CDT AS PLANNED. WINDS AND
WAVES CONTINUE TO RAPIDLY DIMINISH.

HIGH PRESSURE IS TO OUR WEST WITH AN UPPER LEVEL LOW OVER JAMES BAY.
WINDS WILL BE WEAK AND VARY ACROSS THE LAKE TODAY WITH A LAKE BREEZE
EXPECTED ALONG THE IL SHORE.  A COLD FRONT/UPPER LEVEL WAVE PUSHES
SOUTH DOWN THE LAKE TONIGHT THROUGH TOMORROW MORNING. WINDS BECOME
NORTH BEHIND THE FRONT BUT WINDS WILL REMAIN LIGHT AT AROUND 10 KT
DUE TO THE WEAK PRESSURE GRADIENT. AS THE BROAD UPPER TROUGH
ACROSS EASTERN CANADA ROTATES SLOWLY EASTWARD...THE PRESSURE
GRADIENT WILL CONTINUE TO BE LIGHT ACROSS THE LAKE WITH LITTLE IN
THE WAY TO DRIVE WINDS OVER 15 KT INTO THE WEEKEND. AFTERNOON
LAKE BREEZES WILL BE FAVORED IN NEAR SHORE AREAS WITH VARIABLE
WINDS IN THE EVENING OVER A FAIR AMOUNT OF THE LAKE ON MANY
NIGHTS.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 291713
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1213 PM CDT TUE JUL 29 2014

.DISCUSSION...
323 AM CDT

SYNOPSIS...BELOW NORMAL TEMPERATURES CONTINUE THIS WEEK WITH
TEMPERATURES EVER SO SLOWLY MODERATING. THERE IS A CHANCE FOR
AFTERNOON SHOWERS AND THUNDERSTORMS THROUGH SATURDAY WITH THE
BEST CHANCES OF SHOWERS TODAY AND THEN IT APPEARS AGAIN LATE IN
THE WEEK...FRIDAY OR POSSIBLY SATURDAY. WITH THE WINDS CONTINUING
TO EASE OVER THE LAKE...THE BEACH HAZARD STATEMENT WILL END AT
4AM CDT AS PLANNED.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS OVER JAMES BAY WHILE A SURFACE HIGH IS OVER
THE GREAT PLAINS. WITH A WEAK PRESSURE GRADIENT...WINDS WILL WILL
BE LIGHT THIS MORNING. THEY WILL PICK UP AS MIXING GETS GOING BUT
A LAKE BREEZE IS EXPECTED THIS AFTERNOON. HAVE MEDIUM CONFIDENCE
ON HOW FAR INLAND THE LAKE BREEZE PUSHES...BUT EXPECTING
TEMPERATURES TO FALL TO AROUND 70 BEHIND THE LAKE BREEZE. CANNOT
RULE OUT COOLING INTO THE 60S DUE TO UPWELLING OF COOLER LAKE MI
TEMPERATURES FROM THE RECENT STRONG NORTHERLY WINDS. ALL OTHER
LOCATIONS SHOULD SEE HIGHS IN THE MID TO UPPER 70S.

WE WILL HAVE MULTIPLE SOURCES OF FORCING TODAY BETWEEN THE LAKE
BREEZE AND AN UPPER LEVEL VORTICITY STREAMER SWINGING THROUGH THE
REGION. A FEW ISOLATED SHOWERS ARE CURRENTLY OVER CENTRAL WI AND
CENTRAL LAKE MICHIGAN AHEAD OF THAT WAVE. ALL AREAS HAVE A CHANCE
TO SEE ISOLATED TO SCATTERED SHOWERS THIS AFTERNOON. THE BEST
CHANCE AND COVERAGE WILL BE EAST OF A MCHENRY TO FOWLER INDIANA LINE
ALONG THE LAKE BREEZE. ALSO THINKING THE BEST CHANCE FOR
THUNDERSTORMS WILL BE ALONG THE LAKE BREEZE DUE TO THE ADDED
FORCING. THAT BEING SAID...ONLY EXPECTING ISOLATED THUNDERSTORMS
AS CAPE SHOULD BE LIMITED TODAY. MODELS SEEM TO BE OVER DOING
DEWPOINTS A BIT WHICH IS RESULTING IN OVER FORECASTED CAPE VALUES.
NO SEVERE STORMS ARE EXPECTED.

AN UPPER LEVEL WAVE AND COLD FRONT WILL PUSH SOUTH TONIGHT INTO
WEDNESDAY AND LOWS WILL BE IN THE UPPER 50S IN THE OUTLYING AREAS.
DOWNTOWN WILL HAVE A LOW IN THE LOWER 60S.

JEE

WEDNESDAY...
THE AFOREMENTIONED COLD FRONT LOOKS TO LOSE STEAM AS IT MOVES INTO
OUR SOUTHERN FORECAST AREA DUE TO THE UPPER WAVE AND SUPPORT
MOVING MORE EAST THAN SOUTH. THE SLOWER MOVEMENT WILL KEEP THIS
FOCUS...ALBEIT WEAK...IN THE EASTERN FORECAST AREA INTO THE
AFTERNOON. THAT AND ANOTHER LAKE BREEZE COULD PROVIDE FOR A
HANDFUL OF AFTERNOON SHOWERS/STORMS. AGAIN CHANCES ARE LIKELY NOT
AS HIGH AS SOME GUIDANCE IS INDICATING AND THAT LOOKS TO BE
ESPECIALLY TRUE NORTH AND WEST OF I-55. TEMPERATURES ARE EXPECTED
TO BE VERY SIMILAR TO TODAY.

THURSDAY THROUGH THE WEEKEND...
LITTLE PROGRESSION IN THE AMPLIFIED UPPER LEVEL PATTERN IS
FORECAST THROUGH SATURDAY. AS AN ILLUSTRATION OF THIS...FORECAST
SEA LEVEL PRESSURES RANGE FROM 1016MB TO 1019MB FROM THURSDAY
THROUGH SATURDAY NIGHT...I.E. NO CHANGE AND DAILY LAKE BREEZES.
THERE IS ONE FINAL UPPER LEVEL SHORT WAVE ON THE BACKSIDE OF THE
LONG WAVE TROUGH THAT HAS SURPRISINGLY GOOD CONSISTENCY ON THE
EC...GFS...AND GFS ENSEMBLE THAT COULD BRING HIGHER REGIONAL
COVERAGE TO AFTERNOON SHOWERS/STORMS ON FRI AND POSSIBLY ON SAT
DEPENDING ON FEATURE TIMING. ITS A PRETTY SUBTLE FEATURE TO KEY IN
ON AND WITH LITTLE IN THE WAY OF LOW-LEVEL FOCUS HAVE UNDERCUT
MODEL BLEND POPS WHICH ARE BIASED BY WHAT SEEMS TO BE A TOO WET
GFS. DRY WEATHER LOOKS TO OCCUR IN ITS WAKE WITH HIGHER CONFIDENCE
DURING THE LATTER HALF OF THE WEEKEND.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* LAKE BREEZE MAY IMPACT MDW LATER THIS AFTN WITH WINDS SHIFTING
  TO NE OR E BEHIND IT. BREEZE SHOULD STALL BEFORE REACHING ORD.

* ISOL TO SCT SHRA DEVELOP THIS AFTN INTO THE EARLY EVENING. MAY
  SEE A FEW THUNDERSTORMS AS WELL.

* LAKE BREEZE POSSIBLE AGAIN ON WEDNESDAY AFTERNOON.

KJB

//DISCUSSION...UPDATED 18Z...

OBSERVATIONS NEAR THE SHORES OF LAKE MICHIGAN ARE SHOWING SIGNS OF A
LAKE BREEZE DEVELOPING. THIS BOUNDARY WILL LIKELY PUSH INLAND A
LITTLE THIS AFTERNOON...IMPACTING KGYY AND POSSIBLY KMDW LATER IN
THE AFTERNOON. HOWEVER...I HAVE SOME DOUBTS THAT IT WILL MAKE IT TO
MDW GIVEN THE 12-15 KT OF 925 MB WEST-NORTHWESTERLY FLOW THAT IT
WILL BE WORKING AGAINST. FOR NOW...I WILL CONTINUE TO MONITOR THE
TRENDS OF THIS LAKE BREEZE AND MAKE A DECISION LATER OF WHETHER OR
NOT TO REMOVE THE WIND SHIFT FROM THE MDW TAF.

OTHERWISE...THE OTHER CONCERN LATER THIS AFTERNOON AND EVENING IS
THE THREAT FOR SCATTERED SHOWER AND THUNDERSTORM ACTIVITY ACROSS THE
AREA. IT STILL APPEARS THE BEST TIMING FOR ANY ACTIVITY WOULD BE
AFTER 21 UTC THROUGH AROUND 02 UTC THIS EVENING. DUE TO THE
SCATTERED NATURE EXPECTED...I HAVE CONTINUED TO HANDLE THIS CHANCE
WITH A VCSH.

WINDS LOOK TO CONTINUE OUT OF WEST-NORTHWESTERLY DIRECTION INTO
WEDNESDAY. HOWEVER...ANOTHER LAKE BREEZE MAY DEVELOP WEDNESDAY
AFTERNOON...AND DUE TO WEAKER WESTERLY FLOW AROUND 925 MB...THE
BOUNDARY COULD THREATEN THE EASTERN TERMINALS WITH AN EASTERLY WIND
SHIFT LATER IN THE AFTERNOON. CONFIDENCE IS A BIT LOW THIS FAR
OUT...SO I HAVE LEFT THIS MENTION OUT OF THE 30 HOUR ORD TAF.



KJB


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* LOW CONFIDENCE IN LAKE BREEZE IMPACTING THE TERMINALS LATER
  THIS AFTERNOON.

* MEDIUM CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE AREA THIS AFTERNOON.

* LOW CONFIDENCE IN ISOLATED TS IMPACTING THE TERMINALS THIS AFTERNOON.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

KJB

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT...VFR.

THURSDAY THROUGH SATURDAY...PREDOMINANTLY VFR...WITH A CHANCE OF
TSRA IN MAINLY THE AFTERNOON & EARLY EVENING.

SUNDAY...VFR.

MONDAY...SCHC TSRA.

JEE

&&

.MARINE...
323 AM CDT

WILL END THE SMALL CRAFT ADVISORY AT 4AM CDT AS PLANNED. WINDS AND
WAVES CONTINUE TO RAPIDLY DIMINISH.

HIGH PRESSURE IS TO OUR WEST WITH AN UPPER LEVEL LOW OVER JAMES BAY.
WINDS WILL BE WEAK AND VARY ACROSS THE LAKE TODAY WITH A LAKE BREEZE
EXPECTED ALONG THE IL SHORE.  A COLD FRONT/UPPER LEVEL WAVE PUSHES
SOUTH DOWN THE LAKE TONIGHT THROUGH TOMORROW MORNING. WINDS BECOME
NORTH BEHIND THE FRONT BUT WINDS WILL REMAIN LIGHT AT AROUND 10 KT
DUE TO THE WEAK PRESSURE GRADIENT. AS THE BROAD UPPER TROUGH
ACROSS EASTERN CANADA ROTATES SLOWLY EASTWARD...THE PRESSURE
GRADIENT WILL CONTINUE TO BE LIGHT ACROSS THE LAKE WITH LITTLE IN
THE WAY TO DRIVE WINDS OVER 15 KT INTO THE WEEKEND. AFTERNOON
LAKE BREEZES WILL BE FAVORED IN NEAR SHORE AREAS WITH VARIABLE
WINDS IN THE EVENING OVER A FAIR AMOUNT OF THE LAKE ON MANY
NIGHTS.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
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000
FXUS63 KLOT 291555
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1055 AM CDT TUE JUL 29 2014

.DISCUSSION...
323 AM CDT

SYNOPSIS...BELOW NORMAL TEMPERATURES CONTINUE THIS WEEK WITH
TEMPERATURES EVER SO SLOWLY MODERATING. THERE IS A CHANCE FOR
AFTERNOON SHOWERS AND THUNDERSTORMS THROUGH SATURDAY WITH THE
BEST CHANCES OF SHOWERS TODAY AND THEN IT APPEARS AGAIN LATE IN
THE WEEK...FRIDAY OR POSSIBLY SATURDAY. WITH THE WINDS CONTINUING
TO EASE OVER THE LAKE...THE BEACH HAZARD STATEMENT WILL END AT
4AM CDT AS PLANNED.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS OVER JAMES BAY WHILE A SURFACE HIGH IS OVER
THE GREAT PLAINS. WITH A WEAK PRESSURE GRADIENT...WINDS WILL WILL
BE LIGHT THIS MORNING. THEY WILL PICK UP AS MIXING GETS GOING BUT
A LAKE BREEZE IS EXPECTED THIS AFTERNOON. HAVE MEDIUM CONFIDENCE
ON HOW FAR INLAND THE LAKE BREEZE PUSHES...BUT EXPECTING
TEMPERATURES TO FALL TO AROUND 70 BEHIND THE LAKE BREEZE. CANNOT
RULE OUT COOLING INTO THE 60S DUE TO UPWELLING OF COOLER LAKE MI
TEMPERATURES FROM THE RECENT STRONG NORTHERLY WINDS. ALL OTHER
LOCATIONS SHOULD SEE HIGHS IN THE MID TO UPPER 70S.

WE WILL HAVE MULTIPLE SOURCES OF FORCING TODAY BETWEEN THE LAKE
BREEZE AND AN UPPER LEVEL VORTICITY STREAMER SWINGING THROUGH THE
REGION. A FEW ISOLATED SHOWERS ARE CURRENTLY OVER CENTRAL WI AND
CENTRAL LAKE MICHIGAN AHEAD OF THAT WAVE. ALL AREAS HAVE A CHANCE
TO SEE ISOLATED TO SCATTERED SHOWERS THIS AFTERNOON. THE BEST
CHANCE AND COVERAGE WILL BE EAST OF A MCHENRY TO FOWLER INDIANA LINE
ALONG THE LAKE BREEZE. ALSO THINKING THE BEST CHANCE FOR
THUNDERSTORMS WILL BE ALONG THE LAKE BREEZE DUE TO THE ADDED
FORCING. THAT BEING SAID...ONLY EXPECTING ISOLATED THUNDERSTORMS
AS CAPE SHOULD BE LIMITED TODAY. MODELS SEEM TO BE OVER DOING
DEWPOINTS A BIT WHICH IS RESULTING IN OVER FORECASTED CAPE VALUES.
NO SEVERE STORMS ARE EXPECTED.

AN UPPER LEVEL WAVE AND COLD FRONT WILL PUSH SOUTH TONIGHT INTO
WEDNESDAY AND LOWS WILL BE IN THE UPPER 50S IN THE OUTLYING AREAS.
DOWNTOWN WILL HAVE A LOW IN THE LOWER 60S.

JEE

WEDNESDAY...
THE AFOREMENTIONED COLD FRONT LOOKS TO LOSE STEAM AS IT MOVES INTO
OUR SOUTHERN FORECAST AREA DUE TO THE UPPER WAVE AND SUPPORT
MOVING MORE EAST THAN SOUTH. THE SLOWER MOVEMENT WILL KEEP THIS
FOCUS...ALBEIT WEAK...IN THE EASTERN FORECAST AREA INTO THE
AFTERNOON. THAT AND ANOTHER LAKE BREEZE COULD PROVIDE FOR A
HANDFUL OF AFTERNOON SHOWERS/STORMS. AGAIN CHANCES ARE LIKELY NOT
AS HIGH AS SOME GUIDANCE IS INDICATING AND THAT LOOKS TO BE
ESPECIALLY TRUE NORTH AND WEST OF I-55. TEMPERATURES ARE EXPECTED
TO BE VERY SIMILAR TO TODAY.

THURSDAY THROUGH THE WEEKEND...
LITTLE PROGRESSION IN THE AMPLIFIED UPPER LEVEL PATTERN IS
FORECAST THROUGH SATURDAY. AS AN ILLUSTRATION OF THIS...FORECAST
SEA LEVEL PRESSURES RANGE FROM 1016MB TO 1019MB FROM THURSDAY
THROUGH SATURDAY NIGHT...I.E. NO CHANGE AND DAILY LAKE BREEZES.
THERE IS ONE FINAL UPPER LEVEL SHORT WAVE ON THE BACKSIDE OF THE
LONG WAVE TROUGH THAT HAS SURPRISINGLY GOOD CONSISTENCY ON THE
EC...GFS...AND GFS ENSEMBLE THAT COULD BRING HIGHER REGIONAL
COVERAGE TO AFTERNOON SHOWERS/STORMS ON FRI AND POSSIBLY ON SAT
DEPENDING ON FEATURE TIMING. ITS A PRETTY SUBTLE FEATURE TO KEY IN
ON AND WITH LITTLE IN THE WAY OF LOW-LEVEL FOCUS HAVE UNDERCUT
MODEL BLEND POPS WHICH ARE BIASED BY WHAT SEEMS TO BE A TOO WET
GFS. DRY WEATHER LOOKS TO OCCUR IN ITS WAKE WITH HIGHER CONFIDENCE
DURING THE LATTER HALF OF THE WEEKEND.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* LAKE BREEZE MAY IMPACT MDW LATER THIS AFTN WITH WINDS SHIFTING
  TO NE OR E BEHIND IT. BREEZE SHOULD STALL BEFORE REACHING ORD.

* ISOL TO SCT SHRA DEVELOP THIS AFTN INTO THE EARLY EVENING. MAY
  SEE A FEW THUNDERSTORMS AS WELL.

JEE/KB

//DISCUSSION...UPDATED 14Z...
HAD TO DROP THE PROB 30 FOR THUNDER DUE TO THE RESTRICTIONS OF
HAVING IT WITHIN THE FIRST 9 HOURS OF THE FORECAST. AT THIS TIME I
HAVE OPTED TO KEEP A TEMPO GROUP FOR THUNDER OUT OF THE FORECAST
DUE TO UNCERTAINTIES ON THE EXTENT OF THUNDER IN THIS AFTERNOONS
DEVELOPMENT. THERE IS STILL CERTAINLY STILL A LOW END THREAT OF
THUNDER IMPACTING THE AIRFIELDS LATER THIS AFTERNOON AFTER THE
21-22 UTC HOUR.

KB

//DISCUSSION...UPDATED 12Z...

LIGHT AND VARIABLE WINDS WILL BECOME NORTHWEST AROUND 8 KT BY MID
MORNING. A LAKE BREEZE IS EXPECTED AND SHOULD PUSH THROUGH MDW AND
GYY. WINDS WILL TURN EAST AT MDW BEHIND THE LAKE BREEZE AND
NORTHEAST AT GYY. THE BEST CHANCE FOR SHOWERS AND THUNDERSTORMS WILL
BE AROUND THE LAKE BREEZE DUE TO EXTRA FORCING ALONG IT. STILL
HAVE LIMITED CONFIDENCE ON HOW MANY STORMS WILL OCCUR...BUT HAVE
GREATER CONFIDENCE IN SCATTERED SHOWERS AROUND THE TERMINALS.

WINDS SLOWLY BECOME WEST NORTHWEST OVERNIGHT AND THEN NORTHWEST
WEDNESDAY MORNING. VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* LOW-MEDIUM CONFIDENCE IN LAKE BREEZE IMPACTING THE TERMINALS
  LATER THIS AFTERNOON.

* MEDIUM CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE AREA THIS AFTERNOON.

* LOW CONFIDENCE IN ISOLATED TS IMPACTING THE TERMINALS THIS AFTERNOON.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE/KB

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT...VFR.

THURSDAY THROUGH SATURDAY...PREDOMINANTLY VFR...WITH A CHANCE OF
TSRA IN MAINLY THE AFTERNOON & EARLY EVENING.

SUNDAY...VFR.

MONDAY...SCHC TSRA.

JEE

&&

.MARINE...
323 AM CDT

WILL END THE SMALL CRAFT ADVISORY AT 4AM CDT AS PLANNED. WINDS AND
WAVES CONTINUE TO RAPIDLY DIMINISH.

HIGH PRESSURE IS TO OUR WEST WITH AN UPPER LEVEL LOW OVER JAMES BAY.
WINDS WILL BE WEAK AND VARY ACROSS THE LAKE TODAY WITH A LAKE BREEZE
EXPECTED ALONG THE IL SHORE.  A COLD FRONT/UPPER LEVEL WAVE PUSHES
SOUTH DOWN THE LAKE TONIGHT THROUGH TOMORROW MORNING. WINDS BECOME
NORTH BEHIND THE FRONT BUT WINDS WILL REMAIN LIGHT AT AROUND 10 KT
DUE TO THE WEAK PRESSURE GRADIENT. AS THE BROAD UPPER TROUGH
ACROSS EASTERN CANADA ROTATES SLOWLY EASTWARD...THE PRESSURE
GRADIENT WILL CONTINUE TO BE LIGHT ACROSS THE LAKE WITH LITTLE IN
THE WAY TO DRIVE WINDS OVER 15 KT INTO THE WEEKEND. AFTERNOON
LAKE BREEZES WILL BE FAVORED IN NEAR SHORE AREAS WITH VARIABLE
WINDS IN THE EVENING OVER A FAIR AMOUNT OF THE LAKE ON MANY
NIGHTS.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO






000
FXUS63 KLOT 291555
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1055 AM CDT TUE JUL 29 2014

.DISCUSSION...
323 AM CDT

SYNOPSIS...BELOW NORMAL TEMPERATURES CONTINUE THIS WEEK WITH
TEMPERATURES EVER SO SLOWLY MODERATING. THERE IS A CHANCE FOR
AFTERNOON SHOWERS AND THUNDERSTORMS THROUGH SATURDAY WITH THE
BEST CHANCES OF SHOWERS TODAY AND THEN IT APPEARS AGAIN LATE IN
THE WEEK...FRIDAY OR POSSIBLY SATURDAY. WITH THE WINDS CONTINUING
TO EASE OVER THE LAKE...THE BEACH HAZARD STATEMENT WILL END AT
4AM CDT AS PLANNED.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS OVER JAMES BAY WHILE A SURFACE HIGH IS OVER
THE GREAT PLAINS. WITH A WEAK PRESSURE GRADIENT...WINDS WILL WILL
BE LIGHT THIS MORNING. THEY WILL PICK UP AS MIXING GETS GOING BUT
A LAKE BREEZE IS EXPECTED THIS AFTERNOON. HAVE MEDIUM CONFIDENCE
ON HOW FAR INLAND THE LAKE BREEZE PUSHES...BUT EXPECTING
TEMPERATURES TO FALL TO AROUND 70 BEHIND THE LAKE BREEZE. CANNOT
RULE OUT COOLING INTO THE 60S DUE TO UPWELLING OF COOLER LAKE MI
TEMPERATURES FROM THE RECENT STRONG NORTHERLY WINDS. ALL OTHER
LOCATIONS SHOULD SEE HIGHS IN THE MID TO UPPER 70S.

WE WILL HAVE MULTIPLE SOURCES OF FORCING TODAY BETWEEN THE LAKE
BREEZE AND AN UPPER LEVEL VORTICITY STREAMER SWINGING THROUGH THE
REGION. A FEW ISOLATED SHOWERS ARE CURRENTLY OVER CENTRAL WI AND
CENTRAL LAKE MICHIGAN AHEAD OF THAT WAVE. ALL AREAS HAVE A CHANCE
TO SEE ISOLATED TO SCATTERED SHOWERS THIS AFTERNOON. THE BEST
CHANCE AND COVERAGE WILL BE EAST OF A MCHENRY TO FOWLER INDIANA LINE
ALONG THE LAKE BREEZE. ALSO THINKING THE BEST CHANCE FOR
THUNDERSTORMS WILL BE ALONG THE LAKE BREEZE DUE TO THE ADDED
FORCING. THAT BEING SAID...ONLY EXPECTING ISOLATED THUNDERSTORMS
AS CAPE SHOULD BE LIMITED TODAY. MODELS SEEM TO BE OVER DOING
DEWPOINTS A BIT WHICH IS RESULTING IN OVER FORECASTED CAPE VALUES.
NO SEVERE STORMS ARE EXPECTED.

AN UPPER LEVEL WAVE AND COLD FRONT WILL PUSH SOUTH TONIGHT INTO
WEDNESDAY AND LOWS WILL BE IN THE UPPER 50S IN THE OUTLYING AREAS.
DOWNTOWN WILL HAVE A LOW IN THE LOWER 60S.

JEE

WEDNESDAY...
THE AFOREMENTIONED COLD FRONT LOOKS TO LOSE STEAM AS IT MOVES INTO
OUR SOUTHERN FORECAST AREA DUE TO THE UPPER WAVE AND SUPPORT
MOVING MORE EAST THAN SOUTH. THE SLOWER MOVEMENT WILL KEEP THIS
FOCUS...ALBEIT WEAK...IN THE EASTERN FORECAST AREA INTO THE
AFTERNOON. THAT AND ANOTHER LAKE BREEZE COULD PROVIDE FOR A
HANDFUL OF AFTERNOON SHOWERS/STORMS. AGAIN CHANCES ARE LIKELY NOT
AS HIGH AS SOME GUIDANCE IS INDICATING AND THAT LOOKS TO BE
ESPECIALLY TRUE NORTH AND WEST OF I-55. TEMPERATURES ARE EXPECTED
TO BE VERY SIMILAR TO TODAY.

THURSDAY THROUGH THE WEEKEND...
LITTLE PROGRESSION IN THE AMPLIFIED UPPER LEVEL PATTERN IS
FORECAST THROUGH SATURDAY. AS AN ILLUSTRATION OF THIS...FORECAST
SEA LEVEL PRESSURES RANGE FROM 1016MB TO 1019MB FROM THURSDAY
THROUGH SATURDAY NIGHT...I.E. NO CHANGE AND DAILY LAKE BREEZES.
THERE IS ONE FINAL UPPER LEVEL SHORT WAVE ON THE BACKSIDE OF THE
LONG WAVE TROUGH THAT HAS SURPRISINGLY GOOD CONSISTENCY ON THE
EC...GFS...AND GFS ENSEMBLE THAT COULD BRING HIGHER REGIONAL
COVERAGE TO AFTERNOON SHOWERS/STORMS ON FRI AND POSSIBLY ON SAT
DEPENDING ON FEATURE TIMING. ITS A PRETTY SUBTLE FEATURE TO KEY IN
ON AND WITH LITTLE IN THE WAY OF LOW-LEVEL FOCUS HAVE UNDERCUT
MODEL BLEND POPS WHICH ARE BIASED BY WHAT SEEMS TO BE A TOO WET
GFS. DRY WEATHER LOOKS TO OCCUR IN ITS WAKE WITH HIGHER CONFIDENCE
DURING THE LATTER HALF OF THE WEEKEND.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* LAKE BREEZE MAY IMPACT MDW LATER THIS AFTN WITH WINDS SHIFTING
  TO NE OR E BEHIND IT. BREEZE SHOULD STALL BEFORE REACHING ORD.

* ISOL TO SCT SHRA DEVELOP THIS AFTN INTO THE EARLY EVENING. MAY
  SEE A FEW THUNDERSTORMS AS WELL.

JEE/KB

//DISCUSSION...UPDATED 14Z...
HAD TO DROP THE PROB 30 FOR THUNDER DUE TO THE RESTRICTIONS OF
HAVING IT WITHIN THE FIRST 9 HOURS OF THE FORECAST. AT THIS TIME I
HAVE OPTED TO KEEP A TEMPO GROUP FOR THUNDER OUT OF THE FORECAST
DUE TO UNCERTAINTIES ON THE EXTENT OF THUNDER IN THIS AFTERNOONS
DEVELOPMENT. THERE IS STILL CERTAINLY STILL A LOW END THREAT OF
THUNDER IMPACTING THE AIRFIELDS LATER THIS AFTERNOON AFTER THE
21-22 UTC HOUR.

KB

//DISCUSSION...UPDATED 12Z...

LIGHT AND VARIABLE WINDS WILL BECOME NORTHWEST AROUND 8 KT BY MID
MORNING. A LAKE BREEZE IS EXPECTED AND SHOULD PUSH THROUGH MDW AND
GYY. WINDS WILL TURN EAST AT MDW BEHIND THE LAKE BREEZE AND
NORTHEAST AT GYY. THE BEST CHANCE FOR SHOWERS AND THUNDERSTORMS WILL
BE AROUND THE LAKE BREEZE DUE TO EXTRA FORCING ALONG IT. STILL
HAVE LIMITED CONFIDENCE ON HOW MANY STORMS WILL OCCUR...BUT HAVE
GREATER CONFIDENCE IN SCATTERED SHOWERS AROUND THE TERMINALS.

WINDS SLOWLY BECOME WEST NORTHWEST OVERNIGHT AND THEN NORTHWEST
WEDNESDAY MORNING. VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* LOW-MEDIUM CONFIDENCE IN LAKE BREEZE IMPACTING THE TERMINALS
  LATER THIS AFTERNOON.

* MEDIUM CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE AREA THIS AFTERNOON.

* LOW CONFIDENCE IN ISOLATED TS IMPACTING THE TERMINALS THIS AFTERNOON.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE/KB

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT...VFR.

THURSDAY THROUGH SATURDAY...PREDOMINANTLY VFR...WITH A CHANCE OF
TSRA IN MAINLY THE AFTERNOON & EARLY EVENING.

SUNDAY...VFR.

MONDAY...SCHC TSRA.

JEE

&&

.MARINE...
323 AM CDT

WILL END THE SMALL CRAFT ADVISORY AT 4AM CDT AS PLANNED. WINDS AND
WAVES CONTINUE TO RAPIDLY DIMINISH.

HIGH PRESSURE IS TO OUR WEST WITH AN UPPER LEVEL LOW OVER JAMES BAY.
WINDS WILL BE WEAK AND VARY ACROSS THE LAKE TODAY WITH A LAKE BREEZE
EXPECTED ALONG THE IL SHORE.  A COLD FRONT/UPPER LEVEL WAVE PUSHES
SOUTH DOWN THE LAKE TONIGHT THROUGH TOMORROW MORNING. WINDS BECOME
NORTH BEHIND THE FRONT BUT WINDS WILL REMAIN LIGHT AT AROUND 10 KT
DUE TO THE WEAK PRESSURE GRADIENT. AS THE BROAD UPPER TROUGH
ACROSS EASTERN CANADA ROTATES SLOWLY EASTWARD...THE PRESSURE
GRADIENT WILL CONTINUE TO BE LIGHT ACROSS THE LAKE WITH LITTLE IN
THE WAY TO DRIVE WINDS OVER 15 KT INTO THE WEEKEND. AFTERNOON
LAKE BREEZES WILL BE FAVORED IN NEAR SHORE AREAS WITH VARIABLE
WINDS IN THE EVENING OVER A FAIR AMOUNT OF THE LAKE ON MANY
NIGHTS.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KILX 291545
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1045 AM CDT Tue Jul 29 2014

.DISCUSSION...
ISSUED 1045 AM CDT Tue Jul 29 2014

Deep upper trough across the eastern CONUS continues to be the
dominant weather-maker across central Illinois today. Northerly
flow is providing unseasonably cool temperatures, with afternoon
highs once again expected to remain in the 70s. Main question will
be whether or not any showers will develop within the cyclonic
flow pattern aloft. Not really seeing much of anything on the
latest water vapor imagery, so am skeptical any showers will form
today. Will however hold on to just slight chance PoPs northeast
of I-74 as HRRR/NAM12 both develop a few showers across northeast
Illinois late this afternoon. No zone updated needed at this time.

Barnes
&&

.AVIATION...
ISSUED 609 AM CDT Tue Jul 29 2014

VFR conditions will prevail at all central Illinois TAF sites for
the next 24hrs. Mostly clear skies will continue until late
morning then scattered cloud cover will develop with daytime
heating. Cool air aloft may allow a few convective showers to
develop...mainly KPRG-KGBG northward...however any MVFR
cigs/vsbys quite isolated and too low probability for mention in
TAFs. After 00z...any shower activity/cloud cover diminishing.
Winds increasing to NW8-12 kts by 15Z...decreasing to W up to 5
kts after 00Z.

Onton
&&

.PREV DISCUSSION...
ISSUED 308 AM CDT Tue Jul 29 2014
Upper level ridge over the western half of the country, and trof
over the eastern half... putting much of the northern Plains and
the Midwest under northwesterly flow. This pattern sticks around
for the next few days, with weak flow under a building surface
high. Forecast dominated by slowly creeping up temperatures,
though remaining below normal, and afternoon instability showers.
Best chances for precip heading into the weekend, however, with
another wave on its way as well as a kicker to shift the pattern
aloft and move the trof out of the region by the end of the
weekend. Though models are consistent with the overall trend of
the pattern, the details on timing and extent of the afternoon
showers differs here and there...as well as the
timing/impact/strength of the Fri/Friday evening wave.

SHORT TERM...Today and tomorrow...
Each day a degree or two warmer than the previous day.
Northwesterly winds today as the high continues to build into the
region. Tomorrows winds a bit more west/northwesterly and somewhat
lighter. Rain chances today should remain limited to the
northwest. Though a few models are coming in dry...and the GFS the
other extreme with overblown convection... the more high res model
data output in the 4km wrf and the HRRR is showing some shower
activity to the NE. Wave diving into the trof visible on wv sat
imagery this morning will assist the diurnal afternoon development
and cannot completely rule out some isolated shower activity.
However, tomorrows afternoon showers access more instability in
the midlevels, albeit a small amount, and pops spread over much of
ILX tomorrow with the addition of thunder.

LONG TERM...Thursday through Monday...
Continued below normal temps and northwesterly flow through the
end of the week with some small impulses assisting the afternoon
showers.  Models continue to enhance this activity on Thursday
night and into Friday as the impulses start moving into the west
coast and trying to break down the ridging to the west. GFS far
more aggressive with the precip and the ECMWF is timing a little
quicker with the wave and missing the collision with the max
afternoon heating...and therefore much less qpf. Models beginning
to signal the progression of the deep trof out of the region for
late Sunday and into Monday...which would mean a return to warmer
conditions.

HJS

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$







000
FXUS63 KILX 291545
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1045 AM CDT Tue Jul 29 2014

.DISCUSSION...
ISSUED 1045 AM CDT Tue Jul 29 2014

Deep upper trough across the eastern CONUS continues to be the
dominant weather-maker across central Illinois today. Northerly
flow is providing unseasonably cool temperatures, with afternoon
highs once again expected to remain in the 70s. Main question will
be whether or not any showers will develop within the cyclonic
flow pattern aloft. Not really seeing much of anything on the
latest water vapor imagery, so am skeptical any showers will form
today. Will however hold on to just slight chance PoPs northeast
of I-74 as HRRR/NAM12 both develop a few showers across northeast
Illinois late this afternoon. No zone updated needed at this time.

Barnes
&&

.AVIATION...
ISSUED 609 AM CDT Tue Jul 29 2014

VFR conditions will prevail at all central Illinois TAF sites for
the next 24hrs. Mostly clear skies will continue until late
morning then scattered cloud cover will develop with daytime
heating. Cool air aloft may allow a few convective showers to
develop...mainly KPRG-KGBG northward...however any MVFR
cigs/vsbys quite isolated and too low probability for mention in
TAFs. After 00z...any shower activity/cloud cover diminishing.
Winds increasing to NW8-12 kts by 15Z...decreasing to W up to 5
kts after 00Z.

Onton
&&

.PREV DISCUSSION...
ISSUED 308 AM CDT Tue Jul 29 2014
Upper level ridge over the western half of the country, and trof
over the eastern half... putting much of the northern Plains and
the Midwest under northwesterly flow. This pattern sticks around
for the next few days, with weak flow under a building surface
high. Forecast dominated by slowly creeping up temperatures,
though remaining below normal, and afternoon instability showers.
Best chances for precip heading into the weekend, however, with
another wave on its way as well as a kicker to shift the pattern
aloft and move the trof out of the region by the end of the
weekend. Though models are consistent with the overall trend of
the pattern, the details on timing and extent of the afternoon
showers differs here and there...as well as the
timing/impact/strength of the Fri/Friday evening wave.

SHORT TERM...Today and tomorrow...
Each day a degree or two warmer than the previous day.
Northwesterly winds today as the high continues to build into the
region. Tomorrows winds a bit more west/northwesterly and somewhat
lighter. Rain chances today should remain limited to the
northwest. Though a few models are coming in dry...and the GFS the
other extreme with overblown convection... the more high res model
data output in the 4km wrf and the HRRR is showing some shower
activity to the NE. Wave diving into the trof visible on wv sat
imagery this morning will assist the diurnal afternoon development
and cannot completely rule out some isolated shower activity.
However, tomorrows afternoon showers access more instability in
the midlevels, albeit a small amount, and pops spread over much of
ILX tomorrow with the addition of thunder.

LONG TERM...Thursday through Monday...
Continued below normal temps and northwesterly flow through the
end of the week with some small impulses assisting the afternoon
showers.  Models continue to enhance this activity on Thursday
night and into Friday as the impulses start moving into the west
coast and trying to break down the ridging to the west. GFS far
more aggressive with the precip and the ECMWF is timing a little
quicker with the wave and missing the collision with the max
afternoon heating...and therefore much less qpf. Models beginning
to signal the progression of the deep trof out of the region for
late Sunday and into Monday...which would mean a return to warmer
conditions.

HJS

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$








000
FXUS63 KLOT 291405
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
905 AM CDT TUE JUL 29 2014

.DISCUSSION...
323 AM CDT

SYNOPSIS...BELOW NORMAL TEMPERATURES CONTINUE THIS WEEK WITH
TEMPERATURES EVER SO SLOWLY MODERATING. THERE IS A CHANCE FOR
AFTERNOON SHOWERS AND THUNDERSTORMS THROUGH SATURDAY WITH THE
BEST CHANCES OF SHOWERS TODAY AND THEN IT APPEARS AGAIN LATE IN
THE WEEK...FRIDAY OR POSSIBLY SATURDAY. WITH THE WINDS CONTINUING
TO EASE OVER THE LAKE...THE BEACH HAZARD STATEMENT WILL END AT
4AM CDT AS PLANNED.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS OVER JAMES BAY WHILE A SURFACE HIGH IS OVER
THE GREAT PLAINS. WITH A WEAK PRESSURE GRADIENT...WINDS WILL WILL
BE LIGHT THIS MORNING. THEY WILL PICK UP AS MIXING GETS GOING BUT
A LAKE BREEZE IS EXPECTED THIS AFTERNOON. HAVE MEDIUM CONFIDENCE
ON HOW FAR INLAND THE LAKE BREEZE PUSHES...BUT EXPECTING
TEMPERATURES TO FALL TO AROUND 70 BEHIND THE LAKE BREEZE. CANNOT
RULE OUT COOLING INTO THE 60S DUE TO UPWELLING OF COOLER LAKE MI
TEMPERATURES FROM THE RECENT STRONG NORTHERLY WINDS. ALL OTHER
LOCATIONS SHOULD SEE HIGHS IN THE MID TO UPPER 70S.

WE WILL HAVE MULTIPLE SOURCES OF FORCING TODAY BETWEEN THE LAKE
BREEZE AND AN UPPER LEVEL VORTICITY STREAMER SWINGING THROUGH THE
REGION. A FEW ISOLATED SHOWERS ARE CURRENTLY OVER CENTRAL WI AND
CENTRAL LAKE MICHIGAN AHEAD OF THAT WAVE. ALL AREAS HAVE A CHANCE
TO SEE ISOLATED TO SCATTERED SHOWERS THIS AFTERNOON. THE BEST
CHANCE AND COVERAGE WILL BE EAST OF A MCHENRY TO FOWLER INDIANA LINE
ALONG THE LAKE BREEZE. ALSO THINKING THE BEST CHANCE FOR
THUNDERSTORMS WILL BE ALONG THE LAKE BREEZE DUE TO THE ADDED
FORCING. THAT BEING SAID...ONLY EXPECTING ISOLATED THUNDERSTORMS
AS CAPE SHOULD BE LIMITED TODAY. MODELS SEEM TO BE OVER DOING
DEWPOINTS A BIT WHICH IS RESULTING IN OVER FORECASTED CAPE VALUES.
NO SEVERE STORMS ARE EXPECTED.

AN UPPER LEVEL WAVE AND COLD FRONT WILL PUSH SOUTH TONIGHT INTO
WEDNESDAY AND LOWS WILL BE IN THE UPPER 50S IN THE OUTLYING AREAS.
DOWNTOWN WILL HAVE A LOW IN THE LOWER 60S.

JEE

WEDNESDAY...
THE AFOREMENTIONED COLD FRONT LOOKS TO LOSE STEAM AS IT MOVES INTO
OUR SOUTHERN FORECAST AREA DUE TO THE UPPER WAVE AND SUPPORT
MOVING MORE EAST THAN SOUTH. THE SLOWER MOVEMENT WILL KEEP THIS
FOCUS...ALBEIT WEAK...IN THE EASTERN FORECAST AREA INTO THE
AFTERNOON. THAT AND ANOTHER LAKE BREEZE COULD PROVIDE FOR A
HANDFUL OF AFTERNOON SHOWERS/STORMS. AGAIN CHANCES ARE LIKELY NOT
AS HIGH AS SOME GUIDANCE IS INDICATING AND THAT LOOKS TO BE
ESPECIALLY TRUE NORTH AND WEST OF I-55. TEMPERATURES ARE EXPECTED
TO BE VERY SIMILAR TO TODAY.

THURSDAY THROUGH THE WEEKEND...
LITTLE PROGRESSION IN THE AMPLIFIED UPPER LEVEL PATTERN IS
FORECAST THROUGH SATURDAY. AS AN ILLUSTRATION OF THIS...FORECAST
SEA LEVEL PRESSURES RANGE FROM 1016MB TO 1019MB FROM THURSDAY
THROUGH SATURDAY NIGHT...I.E. NO CHANGE AND DAILY LAKE BREEZES.
THERE IS ONE FINAL UPPER LEVEL SHORT WAVE ON THE BACKSIDE OF THE
LONG WAVE TROUGH THAT HAS SURPRISINGLY GOOD CONSISTENCY ON THE
EC...GFS...AND GFS ENSEMBLE THAT COULD BRING HIGHER REGIONAL
COVERAGE TO AFTERNOON SHOWERS/STORMS ON FRI AND POSSIBLY ON SAT
DEPENDING ON FEATURE TIMING. ITS A PRETTY SUBTLE FEATURE TO KEY IN
ON AND WITH LITTLE IN THE WAY OF LOW-LEVEL FOCUS HAVE UNDERCUT
MODEL BLEND POPS WHICH ARE BIASED BY WHAT SEEMS TO BE A TOO WET
GFS. DRY WEATHER LOOKS TO OCCUR IN ITS WAKE WITH HIGHER CONFIDENCE
DURING THE LATTER HALF OF THE WEEKEND.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 14Z...

* LAKE BREEZE MAY IMPACT MDW LATER THIS AFTN WITH WINDS SHIFTING
  TO NE OR E BEHIND IT. BREEZE SHOULD STALL BEFORE REACHING ORD.

* ISOL TO SCT SHRA DEVELOP THIS AFTN INTO THE EARLY EVENING. MAY
  SEE A FEW THUNDERSTORMS AS WELL.

JEE/KB

//DISCUSSION...UPDATED 14Z...
HAD TO DROP THE PROB 30 FOR THUNDER DUE TO THE RESTRICTIONS OF
HAVING IT WITHIN THE FIRST 9 HOURS OF THE FORECAST. AT THIS TIME I
HAVE OPTED TO KEEP A TEMPO GROUP FOR THUNDER OUT OF THE FORECAST
DUE TO UNCERTAINTIES ON THE EXTENT OF THUNDER IN THIS AFTERNOONS
DEVELOPMENT. THERE IS STILL CERTAINLY STILL A LOW END THREAT OF
THUNDER IMPACTING THE AIRFIELDS LATER THIS AFTERNOON AFTER THE
21-22 UTC HOUR.

KB

//DISCUSSION...UPDATED 12Z...

LIGHT AND VARIABLE WINDS WILL BECOME NORTHWEST AROUND 8 KT BY MID
MORNING. A LAKE BREEZE IS EXPECTED AND SHOULD PUSH THROUGH MDW AND
GYY. WINDS WILL TURN EAST AT MDW BEHIND THE LAKE BREEZE AND
NORTHEAST AT GYY. THE BEST CHANCE FOR SHOWERS AND THUNDERSTORMS WILL
BE AROUND THE LAKE BREEZE DUE TO EXTRA FORCING ALONG IT. STILL
HAVE LIMITED CONFIDENCE ON HOW MANY STORMS WILL OCCUR...BUT HAVE
GREATER CONFIDENCE IN SCATTERED SHOWERS AROUND THE TERMINALS.

WINDS SLOWLY BECOME WEST NORTHWEST OVERNIGHT AND THEN NORTHWEST
WEDNESDAY MORNING. VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* LOW-MEDIUM CONFIDENCE IN LAKE BREEZE IMPACTING THE TERMINALS
  LATER THIS AFTERNOON.

* MEDIUM CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE AREA THIS AFTERNOON.

* LOW CONFIDENCE IN ISOLATED TS IMPACTING THE TERMINALS THIS AFTERNOON.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE/KB

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT...VFR.

THURSDAY THROUGH SATURDAY...PREDOMINANTLY VFR...WITH A CHANCE OF
TSRA IN MAINLY THE AFTERNOON & EARLY EVENING.

SUNDAY...VFR.

MONDAY...SCHC TSRA.

JEE

&&

.MARINE...
323 AM CDT

WILL END THE SMALL CRAFT ADVISORY AT 4AM CDT AS PLANNED. WINDS AND
WAVES CONTINUE TO RAPIDLY DIMINISH.

HIGH PRESSURE IS TO OUR WEST WITH AN UPPER LEVEL LOW OVER JAMES BAY.
WINDS WILL BE WEAK AND VARY ACROSS THE LAKE TODAY WITH A LAKE BREEZE
EXPECTED ALONG THE IL SHORE.  A COLD FRONT/UPPER LEVEL WAVE PUSHES
SOUTH DOWN THE LAKE TONIGHT THROUGH TOMORROW MORNING. WINDS BECOME
NORTH BEHIND THE FRONT BUT WINDS WILL REMAIN LIGHT AT AROUND 10 KT
DUE TO THE WEAK PRESSURE GRADIENT. AS THE BROAD UPPER TROUGH
ACROSS EASTERN CANADA ROTATES SLOWLY EASTWARD...THE PRESSURE
GRADIENT WILL CONTINUE TO BE LIGHT ACROSS THE LAKE WITH LITTLE IN
THE WAY TO DRIVE WINDS OVER 15 KT INTO THE WEEKEND. AFTERNOON
LAKE BREEZES WILL BE FAVORED IN NEAR SHORE AREAS WITH VARIABLE
WINDS IN THE EVENING OVER A FAIR AMOUNT OF THE LAKE ON MANY
NIGHTS.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 291405
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
905 AM CDT TUE JUL 29 2014

.DISCUSSION...
323 AM CDT

SYNOPSIS...BELOW NORMAL TEMPERATURES CONTINUE THIS WEEK WITH
TEMPERATURES EVER SO SLOWLY MODERATING. THERE IS A CHANCE FOR
AFTERNOON SHOWERS AND THUNDERSTORMS THROUGH SATURDAY WITH THE
BEST CHANCES OF SHOWERS TODAY AND THEN IT APPEARS AGAIN LATE IN
THE WEEK...FRIDAY OR POSSIBLY SATURDAY. WITH THE WINDS CONTINUING
TO EASE OVER THE LAKE...THE BEACH HAZARD STATEMENT WILL END AT
4AM CDT AS PLANNED.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS OVER JAMES BAY WHILE A SURFACE HIGH IS OVER
THE GREAT PLAINS. WITH A WEAK PRESSURE GRADIENT...WINDS WILL WILL
BE LIGHT THIS MORNING. THEY WILL PICK UP AS MIXING GETS GOING BUT
A LAKE BREEZE IS EXPECTED THIS AFTERNOON. HAVE MEDIUM CONFIDENCE
ON HOW FAR INLAND THE LAKE BREEZE PUSHES...BUT EXPECTING
TEMPERATURES TO FALL TO AROUND 70 BEHIND THE LAKE BREEZE. CANNOT
RULE OUT COOLING INTO THE 60S DUE TO UPWELLING OF COOLER LAKE MI
TEMPERATURES FROM THE RECENT STRONG NORTHERLY WINDS. ALL OTHER
LOCATIONS SHOULD SEE HIGHS IN THE MID TO UPPER 70S.

WE WILL HAVE MULTIPLE SOURCES OF FORCING TODAY BETWEEN THE LAKE
BREEZE AND AN UPPER LEVEL VORTICITY STREAMER SWINGING THROUGH THE
REGION. A FEW ISOLATED SHOWERS ARE CURRENTLY OVER CENTRAL WI AND
CENTRAL LAKE MICHIGAN AHEAD OF THAT WAVE. ALL AREAS HAVE A CHANCE
TO SEE ISOLATED TO SCATTERED SHOWERS THIS AFTERNOON. THE BEST
CHANCE AND COVERAGE WILL BE EAST OF A MCHENRY TO FOWLER INDIANA LINE
ALONG THE LAKE BREEZE. ALSO THINKING THE BEST CHANCE FOR
THUNDERSTORMS WILL BE ALONG THE LAKE BREEZE DUE TO THE ADDED
FORCING. THAT BEING SAID...ONLY EXPECTING ISOLATED THUNDERSTORMS
AS CAPE SHOULD BE LIMITED TODAY. MODELS SEEM TO BE OVER DOING
DEWPOINTS A BIT WHICH IS RESULTING IN OVER FORECASTED CAPE VALUES.
NO SEVERE STORMS ARE EXPECTED.

AN UPPER LEVEL WAVE AND COLD FRONT WILL PUSH SOUTH TONIGHT INTO
WEDNESDAY AND LOWS WILL BE IN THE UPPER 50S IN THE OUTLYING AREAS.
DOWNTOWN WILL HAVE A LOW IN THE LOWER 60S.

JEE

WEDNESDAY...
THE AFOREMENTIONED COLD FRONT LOOKS TO LOSE STEAM AS IT MOVES INTO
OUR SOUTHERN FORECAST AREA DUE TO THE UPPER WAVE AND SUPPORT
MOVING MORE EAST THAN SOUTH. THE SLOWER MOVEMENT WILL KEEP THIS
FOCUS...ALBEIT WEAK...IN THE EASTERN FORECAST AREA INTO THE
AFTERNOON. THAT AND ANOTHER LAKE BREEZE COULD PROVIDE FOR A
HANDFUL OF AFTERNOON SHOWERS/STORMS. AGAIN CHANCES ARE LIKELY NOT
AS HIGH AS SOME GUIDANCE IS INDICATING AND THAT LOOKS TO BE
ESPECIALLY TRUE NORTH AND WEST OF I-55. TEMPERATURES ARE EXPECTED
TO BE VERY SIMILAR TO TODAY.

THURSDAY THROUGH THE WEEKEND...
LITTLE PROGRESSION IN THE AMPLIFIED UPPER LEVEL PATTERN IS
FORECAST THROUGH SATURDAY. AS AN ILLUSTRATION OF THIS...FORECAST
SEA LEVEL PRESSURES RANGE FROM 1016MB TO 1019MB FROM THURSDAY
THROUGH SATURDAY NIGHT...I.E. NO CHANGE AND DAILY LAKE BREEZES.
THERE IS ONE FINAL UPPER LEVEL SHORT WAVE ON THE BACKSIDE OF THE
LONG WAVE TROUGH THAT HAS SURPRISINGLY GOOD CONSISTENCY ON THE
EC...GFS...AND GFS ENSEMBLE THAT COULD BRING HIGHER REGIONAL
COVERAGE TO AFTERNOON SHOWERS/STORMS ON FRI AND POSSIBLY ON SAT
DEPENDING ON FEATURE TIMING. ITS A PRETTY SUBTLE FEATURE TO KEY IN
ON AND WITH LITTLE IN THE WAY OF LOW-LEVEL FOCUS HAVE UNDERCUT
MODEL BLEND POPS WHICH ARE BIASED BY WHAT SEEMS TO BE A TOO WET
GFS. DRY WEATHER LOOKS TO OCCUR IN ITS WAKE WITH HIGHER CONFIDENCE
DURING THE LATTER HALF OF THE WEEKEND.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 14Z...

* LAKE BREEZE MAY IMPACT MDW LATER THIS AFTN WITH WINDS SHIFTING
  TO NE OR E BEHIND IT. BREEZE SHOULD STALL BEFORE REACHING ORD.

* ISOL TO SCT SHRA DEVELOP THIS AFTN INTO THE EARLY EVENING. MAY
  SEE A FEW THUNDERSTORMS AS WELL.

JEE/KB

//DISCUSSION...UPDATED 14Z...
HAD TO DROP THE PROB 30 FOR THUNDER DUE TO THE RESTRICTIONS OF
HAVING IT WITHIN THE FIRST 9 HOURS OF THE FORECAST. AT THIS TIME I
HAVE OPTED TO KEEP A TEMPO GROUP FOR THUNDER OUT OF THE FORECAST
DUE TO UNCERTAINTIES ON THE EXTENT OF THUNDER IN THIS AFTERNOONS
DEVELOPMENT. THERE IS STILL CERTAINLY STILL A LOW END THREAT OF
THUNDER IMPACTING THE AIRFIELDS LATER THIS AFTERNOON AFTER THE
21-22 UTC HOUR.

KB

//DISCUSSION...UPDATED 12Z...

LIGHT AND VARIABLE WINDS WILL BECOME NORTHWEST AROUND 8 KT BY MID
MORNING. A LAKE BREEZE IS EXPECTED AND SHOULD PUSH THROUGH MDW AND
GYY. WINDS WILL TURN EAST AT MDW BEHIND THE LAKE BREEZE AND
NORTHEAST AT GYY. THE BEST CHANCE FOR SHOWERS AND THUNDERSTORMS WILL
BE AROUND THE LAKE BREEZE DUE TO EXTRA FORCING ALONG IT. STILL
HAVE LIMITED CONFIDENCE ON HOW MANY STORMS WILL OCCUR...BUT HAVE
GREATER CONFIDENCE IN SCATTERED SHOWERS AROUND THE TERMINALS.

WINDS SLOWLY BECOME WEST NORTHWEST OVERNIGHT AND THEN NORTHWEST
WEDNESDAY MORNING. VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* LOW-MEDIUM CONFIDENCE IN LAKE BREEZE IMPACTING THE TERMINALS
  LATER THIS AFTERNOON.

* MEDIUM CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE AREA THIS AFTERNOON.

* LOW CONFIDENCE IN ISOLATED TS IMPACTING THE TERMINALS THIS AFTERNOON.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE/KB

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT...VFR.

THURSDAY THROUGH SATURDAY...PREDOMINANTLY VFR...WITH A CHANCE OF
TSRA IN MAINLY THE AFTERNOON & EARLY EVENING.

SUNDAY...VFR.

MONDAY...SCHC TSRA.

JEE

&&

.MARINE...
323 AM CDT

WILL END THE SMALL CRAFT ADVISORY AT 4AM CDT AS PLANNED. WINDS AND
WAVES CONTINUE TO RAPIDLY DIMINISH.

HIGH PRESSURE IS TO OUR WEST WITH AN UPPER LEVEL LOW OVER JAMES BAY.
WINDS WILL BE WEAK AND VARY ACROSS THE LAKE TODAY WITH A LAKE BREEZE
EXPECTED ALONG THE IL SHORE.  A COLD FRONT/UPPER LEVEL WAVE PUSHES
SOUTH DOWN THE LAKE TONIGHT THROUGH TOMORROW MORNING. WINDS BECOME
NORTH BEHIND THE FRONT BUT WINDS WILL REMAIN LIGHT AT AROUND 10 KT
DUE TO THE WEAK PRESSURE GRADIENT. AS THE BROAD UPPER TROUGH
ACROSS EASTERN CANADA ROTATES SLOWLY EASTWARD...THE PRESSURE
GRADIENT WILL CONTINUE TO BE LIGHT ACROSS THE LAKE WITH LITTLE IN
THE WAY TO DRIVE WINDS OVER 15 KT INTO THE WEEKEND. AFTERNOON
LAKE BREEZES WILL BE FAVORED IN NEAR SHORE AREAS WITH VARIABLE
WINDS IN THE EVENING OVER A FAIR AMOUNT OF THE LAKE ON MANY
NIGHTS.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 291405
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
905 AM CDT TUE JUL 29 2014

.DISCUSSION...
323 AM CDT

SYNOPSIS...BELOW NORMAL TEMPERATURES CONTINUE THIS WEEK WITH
TEMPERATURES EVER SO SLOWLY MODERATING. THERE IS A CHANCE FOR
AFTERNOON SHOWERS AND THUNDERSTORMS THROUGH SATURDAY WITH THE
BEST CHANCES OF SHOWERS TODAY AND THEN IT APPEARS AGAIN LATE IN
THE WEEK...FRIDAY OR POSSIBLY SATURDAY. WITH THE WINDS CONTINUING
TO EASE OVER THE LAKE...THE BEACH HAZARD STATEMENT WILL END AT
4AM CDT AS PLANNED.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS OVER JAMES BAY WHILE A SURFACE HIGH IS OVER
THE GREAT PLAINS. WITH A WEAK PRESSURE GRADIENT...WINDS WILL WILL
BE LIGHT THIS MORNING. THEY WILL PICK UP AS MIXING GETS GOING BUT
A LAKE BREEZE IS EXPECTED THIS AFTERNOON. HAVE MEDIUM CONFIDENCE
ON HOW FAR INLAND THE LAKE BREEZE PUSHES...BUT EXPECTING
TEMPERATURES TO FALL TO AROUND 70 BEHIND THE LAKE BREEZE. CANNOT
RULE OUT COOLING INTO THE 60S DUE TO UPWELLING OF COOLER LAKE MI
TEMPERATURES FROM THE RECENT STRONG NORTHERLY WINDS. ALL OTHER
LOCATIONS SHOULD SEE HIGHS IN THE MID TO UPPER 70S.

WE WILL HAVE MULTIPLE SOURCES OF FORCING TODAY BETWEEN THE LAKE
BREEZE AND AN UPPER LEVEL VORTICITY STREAMER SWINGING THROUGH THE
REGION. A FEW ISOLATED SHOWERS ARE CURRENTLY OVER CENTRAL WI AND
CENTRAL LAKE MICHIGAN AHEAD OF THAT WAVE. ALL AREAS HAVE A CHANCE
TO SEE ISOLATED TO SCATTERED SHOWERS THIS AFTERNOON. THE BEST
CHANCE AND COVERAGE WILL BE EAST OF A MCHENRY TO FOWLER INDIANA LINE
ALONG THE LAKE BREEZE. ALSO THINKING THE BEST CHANCE FOR
THUNDERSTORMS WILL BE ALONG THE LAKE BREEZE DUE TO THE ADDED
FORCING. THAT BEING SAID...ONLY EXPECTING ISOLATED THUNDERSTORMS
AS CAPE SHOULD BE LIMITED TODAY. MODELS SEEM TO BE OVER DOING
DEWPOINTS A BIT WHICH IS RESULTING IN OVER FORECASTED CAPE VALUES.
NO SEVERE STORMS ARE EXPECTED.

AN UPPER LEVEL WAVE AND COLD FRONT WILL PUSH SOUTH TONIGHT INTO
WEDNESDAY AND LOWS WILL BE IN THE UPPER 50S IN THE OUTLYING AREAS.
DOWNTOWN WILL HAVE A LOW IN THE LOWER 60S.

JEE

WEDNESDAY...
THE AFOREMENTIONED COLD FRONT LOOKS TO LOSE STEAM AS IT MOVES INTO
OUR SOUTHERN FORECAST AREA DUE TO THE UPPER WAVE AND SUPPORT
MOVING MORE EAST THAN SOUTH. THE SLOWER MOVEMENT WILL KEEP THIS
FOCUS...ALBEIT WEAK...IN THE EASTERN FORECAST AREA INTO THE
AFTERNOON. THAT AND ANOTHER LAKE BREEZE COULD PROVIDE FOR A
HANDFUL OF AFTERNOON SHOWERS/STORMS. AGAIN CHANCES ARE LIKELY NOT
AS HIGH AS SOME GUIDANCE IS INDICATING AND THAT LOOKS TO BE
ESPECIALLY TRUE NORTH AND WEST OF I-55. TEMPERATURES ARE EXPECTED
TO BE VERY SIMILAR TO TODAY.

THURSDAY THROUGH THE WEEKEND...
LITTLE PROGRESSION IN THE AMPLIFIED UPPER LEVEL PATTERN IS
FORECAST THROUGH SATURDAY. AS AN ILLUSTRATION OF THIS...FORECAST
SEA LEVEL PRESSURES RANGE FROM 1016MB TO 1019MB FROM THURSDAY
THROUGH SATURDAY NIGHT...I.E. NO CHANGE AND DAILY LAKE BREEZES.
THERE IS ONE FINAL UPPER LEVEL SHORT WAVE ON THE BACKSIDE OF THE
LONG WAVE TROUGH THAT HAS SURPRISINGLY GOOD CONSISTENCY ON THE
EC...GFS...AND GFS ENSEMBLE THAT COULD BRING HIGHER REGIONAL
COVERAGE TO AFTERNOON SHOWERS/STORMS ON FRI AND POSSIBLY ON SAT
DEPENDING ON FEATURE TIMING. ITS A PRETTY SUBTLE FEATURE TO KEY IN
ON AND WITH LITTLE IN THE WAY OF LOW-LEVEL FOCUS HAVE UNDERCUT
MODEL BLEND POPS WHICH ARE BIASED BY WHAT SEEMS TO BE A TOO WET
GFS. DRY WEATHER LOOKS TO OCCUR IN ITS WAKE WITH HIGHER CONFIDENCE
DURING THE LATTER HALF OF THE WEEKEND.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 14Z...

* LAKE BREEZE MAY IMPACT MDW LATER THIS AFTN WITH WINDS SHIFTING
  TO NE OR E BEHIND IT. BREEZE SHOULD STALL BEFORE REACHING ORD.

* ISOL TO SCT SHRA DEVELOP THIS AFTN INTO THE EARLY EVENING. MAY
  SEE A FEW THUNDERSTORMS AS WELL.

JEE/KB

//DISCUSSION...UPDATED 14Z...
HAD TO DROP THE PROB 30 FOR THUNDER DUE TO THE RESTRICTIONS OF
HAVING IT WITHIN THE FIRST 9 HOURS OF THE FORECAST. AT THIS TIME I
HAVE OPTED TO KEEP A TEMPO GROUP FOR THUNDER OUT OF THE FORECAST
DUE TO UNCERTAINTIES ON THE EXTENT OF THUNDER IN THIS AFTERNOONS
DEVELOPMENT. THERE IS STILL CERTAINLY STILL A LOW END THREAT OF
THUNDER IMPACTING THE AIRFIELDS LATER THIS AFTERNOON AFTER THE
21-22 UTC HOUR.

KB

//DISCUSSION...UPDATED 12Z...

LIGHT AND VARIABLE WINDS WILL BECOME NORTHWEST AROUND 8 KT BY MID
MORNING. A LAKE BREEZE IS EXPECTED AND SHOULD PUSH THROUGH MDW AND
GYY. WINDS WILL TURN EAST AT MDW BEHIND THE LAKE BREEZE AND
NORTHEAST AT GYY. THE BEST CHANCE FOR SHOWERS AND THUNDERSTORMS WILL
BE AROUND THE LAKE BREEZE DUE TO EXTRA FORCING ALONG IT. STILL
HAVE LIMITED CONFIDENCE ON HOW MANY STORMS WILL OCCUR...BUT HAVE
GREATER CONFIDENCE IN SCATTERED SHOWERS AROUND THE TERMINALS.

WINDS SLOWLY BECOME WEST NORTHWEST OVERNIGHT AND THEN NORTHWEST
WEDNESDAY MORNING. VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* LOW-MEDIUM CONFIDENCE IN LAKE BREEZE IMPACTING THE TERMINALS
  LATER THIS AFTERNOON.

* MEDIUM CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE AREA THIS AFTERNOON.

* LOW CONFIDENCE IN ISOLATED TS IMPACTING THE TERMINALS THIS AFTERNOON.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE/KB

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT...VFR.

THURSDAY THROUGH SATURDAY...PREDOMINANTLY VFR...WITH A CHANCE OF
TSRA IN MAINLY THE AFTERNOON & EARLY EVENING.

SUNDAY...VFR.

MONDAY...SCHC TSRA.

JEE

&&

.MARINE...
323 AM CDT

WILL END THE SMALL CRAFT ADVISORY AT 4AM CDT AS PLANNED. WINDS AND
WAVES CONTINUE TO RAPIDLY DIMINISH.

HIGH PRESSURE IS TO OUR WEST WITH AN UPPER LEVEL LOW OVER JAMES BAY.
WINDS WILL BE WEAK AND VARY ACROSS THE LAKE TODAY WITH A LAKE BREEZE
EXPECTED ALONG THE IL SHORE.  A COLD FRONT/UPPER LEVEL WAVE PUSHES
SOUTH DOWN THE LAKE TONIGHT THROUGH TOMORROW MORNING. WINDS BECOME
NORTH BEHIND THE FRONT BUT WINDS WILL REMAIN LIGHT AT AROUND 10 KT
DUE TO THE WEAK PRESSURE GRADIENT. AS THE BROAD UPPER TROUGH
ACROSS EASTERN CANADA ROTATES SLOWLY EASTWARD...THE PRESSURE
GRADIENT WILL CONTINUE TO BE LIGHT ACROSS THE LAKE WITH LITTLE IN
THE WAY TO DRIVE WINDS OVER 15 KT INTO THE WEEKEND. AFTERNOON
LAKE BREEZES WILL BE FAVORED IN NEAR SHORE AREAS WITH VARIABLE
WINDS IN THE EVENING OVER A FAIR AMOUNT OF THE LAKE ON MANY
NIGHTS.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





000
FXUS63 KLOT 291405
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
905 AM CDT TUE JUL 29 2014

.DISCUSSION...
323 AM CDT

SYNOPSIS...BELOW NORMAL TEMPERATURES CONTINUE THIS WEEK WITH
TEMPERATURES EVER SO SLOWLY MODERATING. THERE IS A CHANCE FOR
AFTERNOON SHOWERS AND THUNDERSTORMS THROUGH SATURDAY WITH THE
BEST CHANCES OF SHOWERS TODAY AND THEN IT APPEARS AGAIN LATE IN
THE WEEK...FRIDAY OR POSSIBLY SATURDAY. WITH THE WINDS CONTINUING
TO EASE OVER THE LAKE...THE BEACH HAZARD STATEMENT WILL END AT
4AM CDT AS PLANNED.

TODAY AND TONIGHT...
THE UPPER LEVEL LOW IS OVER JAMES BAY WHILE A SURFACE HIGH IS OVER
THE GREAT PLAINS. WITH A WEAK PRESSURE GRADIENT...WINDS WILL WILL
BE LIGHT THIS MORNING. THEY WILL PICK UP AS MIXING GETS GOING BUT
A LAKE BREEZE IS EXPECTED THIS AFTERNOON. HAVE MEDIUM CONFIDENCE
ON HOW FAR INLAND THE LAKE BREEZE PUSHES...BUT EXPECTING
TEMPERATURES TO FALL TO AROUND 70 BEHIND THE LAKE BREEZE. CANNOT
RULE OUT COOLING INTO THE 60S DUE TO UPWELLING OF COOLER LAKE MI
TEMPERATURES FROM THE RECENT STRONG NORTHERLY WINDS. ALL OTHER
LOCATIONS SHOULD SEE HIGHS IN THE MID TO UPPER 70S.

WE WILL HAVE MULTIPLE SOURCES OF FORCING TODAY BETWEEN THE LAKE
BREEZE AND AN UPPER LEVEL VORTICITY STREAMER SWINGING THROUGH THE
REGION. A FEW ISOLATED SHOWERS ARE CURRENTLY OVER CENTRAL WI AND
CENTRAL LAKE MICHIGAN AHEAD OF THAT WAVE. ALL AREAS HAVE A CHANCE
TO SEE ISOLATED TO SCATTERED SHOWERS THIS AFTERNOON. THE BEST
CHANCE AND COVERAGE WILL BE EAST OF A MCHENRY TO FOWLER INDIANA LINE
ALONG THE LAKE BREEZE. ALSO THINKING THE BEST CHANCE FOR
THUNDERSTORMS WILL BE ALONG THE LAKE BREEZE DUE TO THE ADDED
FORCING. THAT BEING SAID...ONLY EXPECTING ISOLATED THUNDERSTORMS
AS CAPE SHOULD BE LIMITED TODAY. MODELS SEEM TO BE OVER DOING
DEWPOINTS A BIT WHICH IS RESULTING IN OVER FORECASTED CAPE VALUES.
NO SEVERE STORMS ARE EXPECTED.

AN UPPER LEVEL WAVE AND COLD FRONT WILL PUSH SOUTH TONIGHT INTO
WEDNESDAY AND LOWS WILL BE IN THE UPPER 50S IN THE OUTLYING AREAS.
DOWNTOWN WILL HAVE A LOW IN THE LOWER 60S.

JEE

WEDNESDAY...
THE AFOREMENTIONED COLD FRONT LOOKS TO LOSE STEAM AS IT MOVES INTO
OUR SOUTHERN FORECAST AREA DUE TO THE UPPER WAVE AND SUPPORT
MOVING MORE EAST THAN SOUTH. THE SLOWER MOVEMENT WILL KEEP THIS
FOCUS...ALBEIT WEAK...IN THE EASTERN FORECAST AREA INTO THE
AFTERNOON. THAT AND ANOTHER LAKE BREEZE COULD PROVIDE FOR A
HANDFUL OF AFTERNOON SHOWERS/STORMS. AGAIN CHANCES ARE LIKELY NOT
AS HIGH AS SOME GUIDANCE IS INDICATING AND THAT LOOKS TO BE
ESPECIALLY TRUE NORTH AND WEST OF I-55. TEMPERATURES ARE EXPECTED
TO BE VERY SIMILAR TO TODAY.

THURSDAY THROUGH THE WEEKEND...
LITTLE PROGRESSION IN THE AMPLIFIED UPPER LEVEL PATTERN IS
FORECAST THROUGH SATURDAY. AS AN ILLUSTRATION OF THIS...FORECAST
SEA LEVEL PRESSURES RANGE FROM 1016MB TO 1019MB FROM THURSDAY
THROUGH SATURDAY NIGHT...I.E. NO CHANGE AND DAILY LAKE BREEZES.
THERE IS ONE FINAL UPPER LEVEL SHORT WAVE ON THE BACKSIDE OF THE
LONG WAVE TROUGH THAT HAS SURPRISINGLY GOOD CONSISTENCY ON THE
EC...GFS...AND GFS ENSEMBLE THAT COULD BRING HIGHER REGIONAL
COVERAGE TO AFTERNOON SHOWERS/STORMS ON FRI AND POSSIBLY ON SAT
DEPENDING ON FEATURE TIMING. ITS A PRETTY SUBTLE FEATURE TO KEY IN
ON AND WITH LITTLE IN THE WAY OF LOW-LEVEL FOCUS HAVE UNDERCUT
MODEL BLEND POPS WHICH ARE BIASED BY WHAT SEEMS TO BE A TOO WET
GFS. DRY WEATHER LOOKS TO OCCUR IN ITS WAKE WITH HIGHER CONFIDENCE
DURING THE LATTER HALF OF THE WEEKEND.

MTF

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 14Z...

* LAKE BREEZE MAY IMPACT MDW LATER THIS AFTN WITH WINDS SHIFTING
  TO NE OR E BEHIND IT. BREEZE SHOULD STALL BEFORE REACHING ORD.

* ISOL TO SCT SHRA DEVELOP THIS AFTN INTO THE EARLY EVENING. MAY
  SEE A FEW THUNDERSTORMS AS WELL.

JEE/KB

//DISCUSSION...UPDATED 14Z...
HAD TO DROP THE PROB 30 FOR THUNDER DUE TO THE RESTRICTIONS OF
HAVING IT WITHIN THE FIRST 9 HOURS OF THE FORECAST. AT THIS TIME I
HAVE OPTED TO KEEP A TEMPO GROUP FOR THUNDER OUT OF THE FORECAST
DUE TO UNCERTAINTIES ON THE EXTENT OF THUNDER IN THIS AFTERNOONS
DEVELOPMENT. THERE IS STILL CERTAINLY STILL A LOW END THREAT OF
THUNDER IMPACTING THE AIRFIELDS LATER THIS AFTERNOON AFTER THE
21-22 UTC HOUR.

KB

//DISCUSSION...UPDATED 12Z...

LIGHT AND VARIABLE WINDS WILL BECOME NORTHWEST AROUND 8 KT BY MID
MORNING. A LAKE BREEZE IS EXPECTED AND SHOULD PUSH THROUGH MDW AND
GYY. WINDS WILL TURN EAST AT MDW BEHIND THE LAKE BREEZE AND
NORTHEAST AT GYY. THE BEST CHANCE FOR SHOWERS AND THUNDERSTORMS WILL
BE AROUND THE LAKE BREEZE DUE TO EXTRA FORCING ALONG IT. STILL
HAVE LIMITED CONFIDENCE ON HOW MANY STORMS WILL OCCUR...BUT HAVE
GREATER CONFIDENCE IN SCATTERED SHOWERS AROUND THE TERMINALS.

WINDS SLOWLY BECOME WEST NORTHWEST OVERNIGHT AND THEN NORTHWEST
WEDNESDAY MORNING. VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* LOW-MEDIUM CONFIDENCE IN LAKE BREEZE IMPACTING THE TERMINALS
  LATER THIS AFTERNOON.

* MEDIUM CONFIDENCE IN SCT SHRA DEVELOPMENT ACROSS THE AREA THIS AFTERNOON.

* LOW CONFIDENCE IN ISOLATED TS IMPACTING THE TERMINALS THIS AFTERNOON.

* HIGH CONFIDENCE IN ALL OTHER FORECAST ELEMENTS.

JEE/KB

//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...

WEDNESDAY NIGHT...VFR.

THURSDAY THROUGH SATURDAY...PREDOMINANTLY VFR...WITH A CHANCE OF
TSRA IN MAINLY THE AFTERNOON & EARLY EVENING.

SUNDAY...VFR.

MONDAY...SCHC TSRA.

JEE

&&

.MARINE...
323 AM CDT

WILL END THE SMALL CRAFT ADVISORY AT 4AM CDT AS PLANNED. WINDS AND
WAVES CONTINUE TO RAPIDLY DIMINISH.

HIGH PRESSURE IS TO OUR WEST WITH AN UPPER LEVEL LOW OVER JAMES BAY.
WINDS WILL BE WEAK AND VARY ACROSS THE LAKE TODAY WITH A LAKE BREEZE
EXPECTED ALONG THE IL SHORE.  A COLD FRONT/UPPER LEVEL WAVE PUSHES
SOUTH DOWN THE LAKE TONIGHT THROUGH TOMORROW MORNING. WINDS BECOME
NORTH BEHIND THE FRONT BUT WINDS WILL REMAIN LIGHT AT AROUND 10 KT
DUE TO THE WEAK PRESSURE GRADIENT. AS THE BROAD UPPER TROUGH
ACROSS EASTERN CANADA ROTATES SLOWLY EASTWARD...THE PRESSURE
GRADIENT WILL CONTINUE TO BE LIGHT ACROSS THE LAKE WITH LITTLE IN
THE WAY TO DRIVE WINDS OVER 15 KT INTO THE WEEKEND. AFTERNOON
LAKE BREEZES WILL BE FAVORED IN NEAR SHORE AREAS WITH VARIABLE
WINDS IN THE EVENING OVER A FAIR AMOUNT OF THE LAKE ON MANY
NIGHTS.

JEE/MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

$$

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO





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