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000
FXUS63 KILX 171527
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1027 AM CDT Wed Sep 17 2014

.UPDATE...
ISSUED AT 1025 AM CDT WED SEP 17 2014

Updated the forecast earlier this morning to cancel the dense fog
advisory at 9 am over southeast IL. Also increased cloud cover
today especially over central and sw portion of CWA and added 20%
chance of showers along and sw of Rushville to Springfield and
Taylorville line into early afternoon. Highs in the upper 60s to
around 70F looks on track this afternoon with south to southeast
winds less than 10 mph becoming light and variable.

Small MCS over southern MO is tracking ese into mid MS river
valley today and brunt of its showers and thunderstorms will stay
south of central IL CWA. Just a few showers from Schuyler county
south and tracking ese across sw portion of CWA into early
afternoon. Broken to overcast clouds from 5-10k ft as far ne as
Lacon to Decatur to Olney should break up during the afteroon.
Weak surface high pressure over 1018 mb over IN to drift east
across Ohio river valley this afternoon and be close enough to
central IL to keep winds fairly light. Temperatures currently in
the upper 50s and lower 60s shoudl climb another 10 degrees once
sunshine reappears during the mid/late afternoon.

&&

.SHORT TERM...(Today)
ISSUED AT 237 AM CDT WED SEP 17 2014

Recently issued a Dense Fog Advisory across portions of east-central
and southeast Illinois to account for rapidly expanding dense fog.
This dense fog is forming along a northeast-southwest surface ridge
axis, in an area with near zero surface temperature/dew point
spreads and calm winds. It is not entirely clear how far north and
west of the ridge axis a dense fog threat exists, as winds are dead
calm across most of the forecast area. However, a small
temperature/dew point spread exists north/west of the current Dense
Fog Advisory area, and some mid clouds are beginning to spill across
central Illinois from a short wave moving through the plains. These
factors lead me to believe the current advisory should be sufficient.

Aside from the locally dense morning fog, the only forecast problem
for the day revolves around the precipitation threat (if any) from
the wave moving through the Plains. Some of the model guidance is
suggesting the far southern part of the forecast area may be brushed
by light rainfall later today. However, think these precipitation
forecasts are likely too far north. The model consensus has the vort
max with the short wave staying south of the forecast area, along
with the bulk of the isentropic lift ahead of the wave. These
factors, combined with the dry air mass currently in place, support
continuing with our current dry forecast for today. Temperatures
today are likely to be similar to yesterday`s. While weak low
level warm air advection will be taking place, it is likely to be
offset to some degree by additional cloud cover today.

&&

.LONG TERM...(Tonight through Tuesday)
ISSUED AT 237 AM CDT WED SEP 17 2014

High pressure over the Great Lakes to keep us in a dry east to
northeast flow into Thursday evening. After that, incoming shortwave
from the northwest comes into play. As with the daytime models, the
evening runs have continued the trend that the remnant moisture from
Odile will probably make it about as far as Missouri before shunting
southeast, so the incoming wave never really draws from it. This
lessens the threat of widespread heavy rain. The southeast half of
the CWA will likely remain dry through Saturday, while rain chances
increase across the northwest during the afternoon, and the best
chances occur Saturday night.

Sunday may be a bit of a question mark. The GFS and Canadian models
both have a rather clean frontal passage with lingering rain ending
in the morning. However, the latest ECMWF slows the front as a
surface low forms over Kansas, lingering rain across the south half
of the forecast area into Sunday evening. There may be a bit of a
feedback issue with that solution, so will maintain the dry
conditions by Sunday evening.

Rather large surface high will dominate the Midwest early next week,
with dry conditions for a few days.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
ISSUED AT 656 AM CDT WED SEP 17 2014

Patchy, mainly MVFR, early morning fog to start the day across the
central Illinois terminals. Patchy fog is likely to redevelop
again tonight toward the end of the forecast period. Otherwise,
periods of VFR cigs are expected into this afternoon, with clear
skies likely tonight. Light/variable winds with a ridge of high
pressure nearby today, will trend light/northeast for tonight.


&&

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

&&

$$

UPDATE...07
SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...BAK








000
FXUS63 KILX 171527
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1027 AM CDT Wed Sep 17 2014

.UPDATE...
ISSUED AT 1025 AM CDT WED SEP 17 2014

Updated the forecast earlier this morning to cancel the dense fog
advisory at 9 am over southeast IL. Also increased cloud cover
today especially over central and sw portion of CWA and added 20%
chance of showers along and sw of Rushville to Springfield and
Taylorville line into early afternoon. Highs in the upper 60s to
around 70F looks on track this afternoon with south to southeast
winds less than 10 mph becoming light and variable.

Small MCS over southern MO is tracking ese into mid MS river
valley today and brunt of its showers and thunderstorms will stay
south of central IL CWA. Just a few showers from Schuyler county
south and tracking ese across sw portion of CWA into early
afternoon. Broken to overcast clouds from 5-10k ft as far ne as
Lacon to Decatur to Olney should break up during the afteroon.
Weak surface high pressure over 1018 mb over IN to drift east
across Ohio river valley this afternoon and be close enough to
central IL to keep winds fairly light. Temperatures currently in
the upper 50s and lower 60s shoudl climb another 10 degrees once
sunshine reappears during the mid/late afternoon.

&&

.SHORT TERM...(Today)
ISSUED AT 237 AM CDT WED SEP 17 2014

Recently issued a Dense Fog Advisory across portions of east-central
and southeast Illinois to account for rapidly expanding dense fog.
This dense fog is forming along a northeast-southwest surface ridge
axis, in an area with near zero surface temperature/dew point
spreads and calm winds. It is not entirely clear how far north and
west of the ridge axis a dense fog threat exists, as winds are dead
calm across most of the forecast area. However, a small
temperature/dew point spread exists north/west of the current Dense
Fog Advisory area, and some mid clouds are beginning to spill across
central Illinois from a short wave moving through the plains. These
factors lead me to believe the current advisory should be sufficient.

Aside from the locally dense morning fog, the only forecast problem
for the day revolves around the precipitation threat (if any) from
the wave moving through the Plains. Some of the model guidance is
suggesting the far southern part of the forecast area may be brushed
by light rainfall later today. However, think these precipitation
forecasts are likely too far north. The model consensus has the vort
max with the short wave staying south of the forecast area, along
with the bulk of the isentropic lift ahead of the wave. These
factors, combined with the dry air mass currently in place, support
continuing with our current dry forecast for today. Temperatures
today are likely to be similar to yesterday`s. While weak low
level warm air advection will be taking place, it is likely to be
offset to some degree by additional cloud cover today.

&&

.LONG TERM...(Tonight through Tuesday)
ISSUED AT 237 AM CDT WED SEP 17 2014

High pressure over the Great Lakes to keep us in a dry east to
northeast flow into Thursday evening. After that, incoming shortwave
from the northwest comes into play. As with the daytime models, the
evening runs have continued the trend that the remnant moisture from
Odile will probably make it about as far as Missouri before shunting
southeast, so the incoming wave never really draws from it. This
lessens the threat of widespread heavy rain. The southeast half of
the CWA will likely remain dry through Saturday, while rain chances
increase across the northwest during the afternoon, and the best
chances occur Saturday night.

Sunday may be a bit of a question mark. The GFS and Canadian models
both have a rather clean frontal passage with lingering rain ending
in the morning. However, the latest ECMWF slows the front as a
surface low forms over Kansas, lingering rain across the south half
of the forecast area into Sunday evening. There may be a bit of a
feedback issue with that solution, so will maintain the dry
conditions by Sunday evening.

Rather large surface high will dominate the Midwest early next week,
with dry conditions for a few days.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
ISSUED AT 656 AM CDT WED SEP 17 2014

Patchy, mainly MVFR, early morning fog to start the day across the
central Illinois terminals. Patchy fog is likely to redevelop
again tonight toward the end of the forecast period. Otherwise,
periods of VFR cigs are expected into this afternoon, with clear
skies likely tonight. Light/variable winds with a ridge of high
pressure nearby today, will trend light/northeast for tonight.


&&

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

&&

$$

UPDATE...07
SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...BAK








000
FXUS63 KILX 171527
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1027 AM CDT Wed Sep 17 2014

.UPDATE...
ISSUED AT 1025 AM CDT WED SEP 17 2014

Updated the forecast earlier this morning to cancel the dense fog
advisory at 9 am over southeast IL. Also increased cloud cover
today especially over central and sw portion of CWA and added 20%
chance of showers along and sw of Rushville to Springfield and
Taylorville line into early afternoon. Highs in the upper 60s to
around 70F looks on track this afternoon with south to southeast
winds less than 10 mph becoming light and variable.

Small MCS over southern MO is tracking ese into mid MS river
valley today and brunt of its showers and thunderstorms will stay
south of central IL CWA. Just a few showers from Schuyler county
south and tracking ese across sw portion of CWA into early
afternoon. Broken to overcast clouds from 5-10k ft as far ne as
Lacon to Decatur to Olney should break up during the afteroon.
Weak surface high pressure over 1018 mb over IN to drift east
across Ohio river valley this afternoon and be close enough to
central IL to keep winds fairly light. Temperatures currently in
the upper 50s and lower 60s shoudl climb another 10 degrees once
sunshine reappears during the mid/late afternoon.

&&

.SHORT TERM...(Today)
ISSUED AT 237 AM CDT WED SEP 17 2014

Recently issued a Dense Fog Advisory across portions of east-central
and southeast Illinois to account for rapidly expanding dense fog.
This dense fog is forming along a northeast-southwest surface ridge
axis, in an area with near zero surface temperature/dew point
spreads and calm winds. It is not entirely clear how far north and
west of the ridge axis a dense fog threat exists, as winds are dead
calm across most of the forecast area. However, a small
temperature/dew point spread exists north/west of the current Dense
Fog Advisory area, and some mid clouds are beginning to spill across
central Illinois from a short wave moving through the plains. These
factors lead me to believe the current advisory should be sufficient.

Aside from the locally dense morning fog, the only forecast problem
for the day revolves around the precipitation threat (if any) from
the wave moving through the Plains. Some of the model guidance is
suggesting the far southern part of the forecast area may be brushed
by light rainfall later today. However, think these precipitation
forecasts are likely too far north. The model consensus has the vort
max with the short wave staying south of the forecast area, along
with the bulk of the isentropic lift ahead of the wave. These
factors, combined with the dry air mass currently in place, support
continuing with our current dry forecast for today. Temperatures
today are likely to be similar to yesterday`s. While weak low
level warm air advection will be taking place, it is likely to be
offset to some degree by additional cloud cover today.

&&

.LONG TERM...(Tonight through Tuesday)
ISSUED AT 237 AM CDT WED SEP 17 2014

High pressure over the Great Lakes to keep us in a dry east to
northeast flow into Thursday evening. After that, incoming shortwave
from the northwest comes into play. As with the daytime models, the
evening runs have continued the trend that the remnant moisture from
Odile will probably make it about as far as Missouri before shunting
southeast, so the incoming wave never really draws from it. This
lessens the threat of widespread heavy rain. The southeast half of
the CWA will likely remain dry through Saturday, while rain chances
increase across the northwest during the afternoon, and the best
chances occur Saturday night.

Sunday may be a bit of a question mark. The GFS and Canadian models
both have a rather clean frontal passage with lingering rain ending
in the morning. However, the latest ECMWF slows the front as a
surface low forms over Kansas, lingering rain across the south half
of the forecast area into Sunday evening. There may be a bit of a
feedback issue with that solution, so will maintain the dry
conditions by Sunday evening.

Rather large surface high will dominate the Midwest early next week,
with dry conditions for a few days.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
ISSUED AT 656 AM CDT WED SEP 17 2014

Patchy, mainly MVFR, early morning fog to start the day across the
central Illinois terminals. Patchy fog is likely to redevelop
again tonight toward the end of the forecast period. Otherwise,
periods of VFR cigs are expected into this afternoon, with clear
skies likely tonight. Light/variable winds with a ridge of high
pressure nearby today, will trend light/northeast for tonight.


&&

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

&&

$$

UPDATE...07
SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...BAK








000
FXUS63 KILX 171527
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1027 AM CDT Wed Sep 17 2014

.UPDATE...
ISSUED AT 1025 AM CDT WED SEP 17 2014

Updated the forecast earlier this morning to cancel the dense fog
advisory at 9 am over southeast IL. Also increased cloud cover
today especially over central and sw portion of CWA and added 20%
chance of showers along and sw of Rushville to Springfield and
Taylorville line into early afternoon. Highs in the upper 60s to
around 70F looks on track this afternoon with south to southeast
winds less than 10 mph becoming light and variable.

Small MCS over southern MO is tracking ese into mid MS river
valley today and brunt of its showers and thunderstorms will stay
south of central IL CWA. Just a few showers from Schuyler county
south and tracking ese across sw portion of CWA into early
afternoon. Broken to overcast clouds from 5-10k ft as far ne as
Lacon to Decatur to Olney should break up during the afteroon.
Weak surface high pressure over 1018 mb over IN to drift east
across Ohio river valley this afternoon and be close enough to
central IL to keep winds fairly light. Temperatures currently in
the upper 50s and lower 60s shoudl climb another 10 degrees once
sunshine reappears during the mid/late afternoon.

&&

.SHORT TERM...(Today)
ISSUED AT 237 AM CDT WED SEP 17 2014

Recently issued a Dense Fog Advisory across portions of east-central
and southeast Illinois to account for rapidly expanding dense fog.
This dense fog is forming along a northeast-southwest surface ridge
axis, in an area with near zero surface temperature/dew point
spreads and calm winds. It is not entirely clear how far north and
west of the ridge axis a dense fog threat exists, as winds are dead
calm across most of the forecast area. However, a small
temperature/dew point spread exists north/west of the current Dense
Fog Advisory area, and some mid clouds are beginning to spill across
central Illinois from a short wave moving through the plains. These
factors lead me to believe the current advisory should be sufficient.

Aside from the locally dense morning fog, the only forecast problem
for the day revolves around the precipitation threat (if any) from
the wave moving through the Plains. Some of the model guidance is
suggesting the far southern part of the forecast area may be brushed
by light rainfall later today. However, think these precipitation
forecasts are likely too far north. The model consensus has the vort
max with the short wave staying south of the forecast area, along
with the bulk of the isentropic lift ahead of the wave. These
factors, combined with the dry air mass currently in place, support
continuing with our current dry forecast for today. Temperatures
today are likely to be similar to yesterday`s. While weak low
level warm air advection will be taking place, it is likely to be
offset to some degree by additional cloud cover today.

&&

.LONG TERM...(Tonight through Tuesday)
ISSUED AT 237 AM CDT WED SEP 17 2014

High pressure over the Great Lakes to keep us in a dry east to
northeast flow into Thursday evening. After that, incoming shortwave
from the northwest comes into play. As with the daytime models, the
evening runs have continued the trend that the remnant moisture from
Odile will probably make it about as far as Missouri before shunting
southeast, so the incoming wave never really draws from it. This
lessens the threat of widespread heavy rain. The southeast half of
the CWA will likely remain dry through Saturday, while rain chances
increase across the northwest during the afternoon, and the best
chances occur Saturday night.

Sunday may be a bit of a question mark. The GFS and Canadian models
both have a rather clean frontal passage with lingering rain ending
in the morning. However, the latest ECMWF slows the front as a
surface low forms over Kansas, lingering rain across the south half
of the forecast area into Sunday evening. There may be a bit of a
feedback issue with that solution, so will maintain the dry
conditions by Sunday evening.

Rather large surface high will dominate the Midwest early next week,
with dry conditions for a few days.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
ISSUED AT 656 AM CDT WED SEP 17 2014

Patchy, mainly MVFR, early morning fog to start the day across the
central Illinois terminals. Patchy fog is likely to redevelop
again tonight toward the end of the forecast period. Otherwise,
periods of VFR cigs are expected into this afternoon, with clear
skies likely tonight. Light/variable winds with a ridge of high
pressure nearby today, will trend light/northeast for tonight.


&&

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

&&

$$

UPDATE...07
SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...BAK







  [top]

000
FXUS63 KLOT 171353
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
853 AM CDT WED SEP 17 2014

.DISCUSSION...
231 AM CDT

OVERARCHING THEME OF THE FORECAST FOR THE NEXT SEVEN DAYS IS FAIRLY
NICE EARLY FALL WEATHER WITH A DASH OF UNSEASONABLE WARMTH AND
SPLASH OF THUNDERSTORMS.

TODAY LOOKS TO BE ANOTHER GLORIOUS DAY...LIKELY A COUPLE/FEW DEGREES
WARMER THAN TUESDAY. GUIDANCE WAS A COUPLE DEGREES TOO COOL WITH
HIGHS TUESDAY AND WITH 925MB AND 850MB TEMPS PROGGED TO BE 2-3C
WARMER THAN YESTERDAY HAVE OPTED TO GO A COUPLE DEGREES ABOVE
GUIDANCE WITH HIGHS NEAR OR INTO THE LOWER 70S MOST AREAS. SOME
ACCAS AND MID LEVEL CLOUDINESS UPSTREAM ASSOCIATED WITH MID-LEVEL
WARM AIR ADVECTION COULD LEAD TO A BIT MORE CLOUDINESS THAN THE
NEARLY CLOUD FREE SKIES TUESDAY BUT STILL LOOK FOR PLENTY OF
SUNSHINE TODAY.

WEAKENING BACKDOOR COLD FRONT MOVES IN OFF THE LAKE EARLY THURSDAY
MORNING RESULTING IN SOME SLIGHTLY COOLER TEMPS THURS...ESPECIALLY
DOWNWIND OF THE LAKE WHERE NORTHEAST WINDS WILL HAVE A BETTER UMPH
BEHIND THE FRONT AND RESULT IN A GREATER LAKE INFLUENCE TO TEMPS.
WINDS BEGIN TO VEER AND SHOULD BECOMING SOUTHEASTERLY THURSDAY NIGHT
WITH WARM AIR ADVECTION GETTING UNDERWAY. WARM AIR ADVECTION GETS
GOING INTO FULL GEAR BY LATE FRIDAY AND GIVEN THE LATER ARRIVAL OF
THE TOASTIER TEMPS ITS UNCLEAR HOW MUCH WARMING WILL BE REALIZED
WITH HIGHS FRIDAY. HAVE CONSERVATIVELY BUMPED TEMPS UP INTO THE 70S
AREA WIDE...BUT PROGGED 00Z 850MB/925MB TEMPS WOULD ACTUALLY SUPPORT
TEMPS AROUND 80F. FRIDAY NIGHT LOOKS TO BE FAIRLY WARM WITH
SOUTHERLY WINDS CONTINUING...IN FACT MANY AREAS WILL SEE LOW TEMPS
FRI NIGHT WARMER THAN HIGH TEMPS WERE LAST WEEK! GUIDANCE CONTINUES
TO ADVERTISE 850MB TEMPS IN THE MID-UPPER TEENS WITH 925MB TEMPS
AROUND 20C...WHICH CLIMO SUGGESTS HIGHS WELL INTO THE 80S. HAVE
TRENDED TEMPS UPWARD SOME INTO THE LOW TO MID 80S AND WITH ENOUGH
SUNSHINE EVEN THOSE FORECAST HIGHS COULD END UP BEING A BIT TOO LOW!

COLD FRONT STILL LOOKS SLATED TO ARRIVE LATE SATURDAY WITH SHOWERS
AND THUNDERSTORMS CERTAINLY LOOKING LIKE A DECENT BET ALONG THE
FRONT. MEDIUM RANGE GUIDANCE HAS TRENDED TOWARD LESS PHASING WITH
THE NORTHERN STREAM TROUGH AND THE REMNANTS OF ODILE...SO NOT
LOOKING LIKE QUITE AS BIG OF A RAIN PRODUCER AS PREVIOUS RUNS
SUGGESTED. THE PUSH OF COLDER AIR BEHIND THE FRONT SATURDAY LOOKS TO
COME IN PHASES...WITH THE FIRST PHASE INITIALLY LOOKING LIKE MORE OF
A PUSH OF PACIFIC AIR SUNDAY BEFORE SECONDARY PUSH OF MORE
SUBSTANTIAL COLD AIR ARRIVES EARLY NEXT WEEK SENDING TEMPS DROPPING
BELOW AVERAGE AGAIN.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 14Z...

* LAKE BREEZE THIS AFTERNOON.

* COLD FRONT PASSAGE EARLY THURSDAY WITH POSSIBILITY OF LOWER
  STRATUS BEHIND.

KREIN

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

HIGH PRESSURE WILL BE IN PLACE TODAY WITH CONTINUED LIGHT WINDS AND
PRIMARILY VFR CONDITIONS OUTSIDE OF EARLY MORNING FOG. CONFIDENCE IN
WIND DIRECTION IS LOWER MAINLY DUE TO THE OVERALL LIGHT
MAGNITUDE...BUT EXPECT A GENERALLY SOUTHWEST WIND EARLY THIS MORNING
TO GRADUALLY VEER TO NORTHWEST BY EARLY AFTERNOON...THEN A LAKE
BREEZE WILL TURN WINDS EASTERLY MID TO LATE THIS AFTERNOON.
THROUGHOUT WINDS SHOULD REMAIN LESS THAN 10 KT. MOSTLY SUNNY SKIES
WILL BE IN PLACE AGAIN TODAY WITH A FEW MORE MID AND HIGH CLOUDS AS
COMPARED TO YESTERDAY. WINDS ARE EXPECTED TO GO LIGHT AND VARIABLE
OVERNIGHT...THEN LATE TONIGHT INTO EARLY THURSDAY A COLD FRONT WILL
DROP ACROSS THE REGION TURNING WINDS BACK TO THE NORTHEAST. SOME
MODELS HINT AT THE POSSIBILITY OF SOME MVFR STRATUS COMING IN BEHIND
THE FRONT.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* MEDIUM-HIGH CONFIDENCE IN LAKE BREEZE TIMING TO WITHIN AN HOUR
  OR TWO.

* LOW CONFIDENCE IN CIGS THURSDAY MORNING.

* HIGH CONFIDENCE IN VFR CONDITIONS TODAY AND MOST OF TONIGHT.

* HIGH CONFIDENCE IN WINDS LESS THAN 10 KT.

KREIN

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

THURSDAY NIGHT THROUGH FRIDAY...VFR
SATURDAY...CHANCE OF THUNDERSTORMS.
SUNDAY THROUGH TUESDAY...VFR.

BMD

&&

.MARINE...
222 AM CDT

AREAS OF HIGH PRESSURE LIE ACROSS THE OHIO VALLEY AND THE CANADIAN
PRAIRIES EARLY THIS MORNING WITH COLD FRONT IN BETWEEN THESE TWO
FEATURES JUST NORTH OF LAKE MICHIGAN. THIS FRONT WILL MOVE SOUTH
ACROSS THE LAKE THIS EVENING AND TONIGHT WITH WINDS TURNING
NORTHEAST AND INCREASING SHARPLY INTO THE 20-25 KT RANGE
PARTICULARLY OVER THE NORTH HALF OF THE LAKE. WINDS DIMINISH
THURSDAY..THEN TURN BACK TO THE SOUTHEAST AND INCREASE AGAIN
THURSDAY NIGHT INTO FRIDAY. BY FRIDAY...SOUTH WINDS TO 30 KT ARE
EXPECTED OVER THE NORTH HALF OF THE LAKE AND A BRIEF PERIOD OF SOUTH
GALES IS NOT OUT OF THE QUESTION. WINDS WILL REMAIN FRESH THROUGH
THE WEEKEND...TURNING NORTHWEST ON SUNDAY AS ANOTHER COLD FRONT
MOVES ACROSS THE LAKE.

BMD

&&

.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 171353
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
853 AM CDT WED SEP 17 2014

.DISCUSSION...
231 AM CDT

OVERARCHING THEME OF THE FORECAST FOR THE NEXT SEVEN DAYS IS FAIRLY
NICE EARLY FALL WEATHER WITH A DASH OF UNSEASONABLE WARMTH AND
SPLASH OF THUNDERSTORMS.

TODAY LOOKS TO BE ANOTHER GLORIOUS DAY...LIKELY A COUPLE/FEW DEGREES
WARMER THAN TUESDAY. GUIDANCE WAS A COUPLE DEGREES TOO COOL WITH
HIGHS TUESDAY AND WITH 925MB AND 850MB TEMPS PROGGED TO BE 2-3C
WARMER THAN YESTERDAY HAVE OPTED TO GO A COUPLE DEGREES ABOVE
GUIDANCE WITH HIGHS NEAR OR INTO THE LOWER 70S MOST AREAS. SOME
ACCAS AND MID LEVEL CLOUDINESS UPSTREAM ASSOCIATED WITH MID-LEVEL
WARM AIR ADVECTION COULD LEAD TO A BIT MORE CLOUDINESS THAN THE
NEARLY CLOUD FREE SKIES TUESDAY BUT STILL LOOK FOR PLENTY OF
SUNSHINE TODAY.

WEAKENING BACKDOOR COLD FRONT MOVES IN OFF THE LAKE EARLY THURSDAY
MORNING RESULTING IN SOME SLIGHTLY COOLER TEMPS THURS...ESPECIALLY
DOWNWIND OF THE LAKE WHERE NORTHEAST WINDS WILL HAVE A BETTER UMPH
BEHIND THE FRONT AND RESULT IN A GREATER LAKE INFLUENCE TO TEMPS.
WINDS BEGIN TO VEER AND SHOULD BECOMING SOUTHEASTERLY THURSDAY NIGHT
WITH WARM AIR ADVECTION GETTING UNDERWAY. WARM AIR ADVECTION GETS
GOING INTO FULL GEAR BY LATE FRIDAY AND GIVEN THE LATER ARRIVAL OF
THE TOASTIER TEMPS ITS UNCLEAR HOW MUCH WARMING WILL BE REALIZED
WITH HIGHS FRIDAY. HAVE CONSERVATIVELY BUMPED TEMPS UP INTO THE 70S
AREA WIDE...BUT PROGGED 00Z 850MB/925MB TEMPS WOULD ACTUALLY SUPPORT
TEMPS AROUND 80F. FRIDAY NIGHT LOOKS TO BE FAIRLY WARM WITH
SOUTHERLY WINDS CONTINUING...IN FACT MANY AREAS WILL SEE LOW TEMPS
FRI NIGHT WARMER THAN HIGH TEMPS WERE LAST WEEK! GUIDANCE CONTINUES
TO ADVERTISE 850MB TEMPS IN THE MID-UPPER TEENS WITH 925MB TEMPS
AROUND 20C...WHICH CLIMO SUGGESTS HIGHS WELL INTO THE 80S. HAVE
TRENDED TEMPS UPWARD SOME INTO THE LOW TO MID 80S AND WITH ENOUGH
SUNSHINE EVEN THOSE FORECAST HIGHS COULD END UP BEING A BIT TOO LOW!

COLD FRONT STILL LOOKS SLATED TO ARRIVE LATE SATURDAY WITH SHOWERS
AND THUNDERSTORMS CERTAINLY LOOKING LIKE A DECENT BET ALONG THE
FRONT. MEDIUM RANGE GUIDANCE HAS TRENDED TOWARD LESS PHASING WITH
THE NORTHERN STREAM TROUGH AND THE REMNANTS OF ODILE...SO NOT
LOOKING LIKE QUITE AS BIG OF A RAIN PRODUCER AS PREVIOUS RUNS
SUGGESTED. THE PUSH OF COLDER AIR BEHIND THE FRONT SATURDAY LOOKS TO
COME IN PHASES...WITH THE FIRST PHASE INITIALLY LOOKING LIKE MORE OF
A PUSH OF PACIFIC AIR SUNDAY BEFORE SECONDARY PUSH OF MORE
SUBSTANTIAL COLD AIR ARRIVES EARLY NEXT WEEK SENDING TEMPS DROPPING
BELOW AVERAGE AGAIN.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 14Z...

* LAKE BREEZE THIS AFTERNOON.

* COLD FRONT PASSAGE EARLY THURSDAY WITH POSSIBILITY OF LOWER
  STRATUS BEHIND.

KREIN

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

HIGH PRESSURE WILL BE IN PLACE TODAY WITH CONTINUED LIGHT WINDS AND
PRIMARILY VFR CONDITIONS OUTSIDE OF EARLY MORNING FOG. CONFIDENCE IN
WIND DIRECTION IS LOWER MAINLY DUE TO THE OVERALL LIGHT
MAGNITUDE...BUT EXPECT A GENERALLY SOUTHWEST WIND EARLY THIS MORNING
TO GRADUALLY VEER TO NORTHWEST BY EARLY AFTERNOON...THEN A LAKE
BREEZE WILL TURN WINDS EASTERLY MID TO LATE THIS AFTERNOON.
THROUGHOUT WINDS SHOULD REMAIN LESS THAN 10 KT. MOSTLY SUNNY SKIES
WILL BE IN PLACE AGAIN TODAY WITH A FEW MORE MID AND HIGH CLOUDS AS
COMPARED TO YESTERDAY. WINDS ARE EXPECTED TO GO LIGHT AND VARIABLE
OVERNIGHT...THEN LATE TONIGHT INTO EARLY THURSDAY A COLD FRONT WILL
DROP ACROSS THE REGION TURNING WINDS BACK TO THE NORTHEAST. SOME
MODELS HINT AT THE POSSIBILITY OF SOME MVFR STRATUS COMING IN BEHIND
THE FRONT.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* MEDIUM-HIGH CONFIDENCE IN LAKE BREEZE TIMING TO WITHIN AN HOUR
  OR TWO.

* LOW CONFIDENCE IN CIGS THURSDAY MORNING.

* HIGH CONFIDENCE IN VFR CONDITIONS TODAY AND MOST OF TONIGHT.

* HIGH CONFIDENCE IN WINDS LESS THAN 10 KT.

KREIN

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

THURSDAY NIGHT THROUGH FRIDAY...VFR
SATURDAY...CHANCE OF THUNDERSTORMS.
SUNDAY THROUGH TUESDAY...VFR.

BMD

&&

.MARINE...
222 AM CDT

AREAS OF HIGH PRESSURE LIE ACROSS THE OHIO VALLEY AND THE CANADIAN
PRAIRIES EARLY THIS MORNING WITH COLD FRONT IN BETWEEN THESE TWO
FEATURES JUST NORTH OF LAKE MICHIGAN. THIS FRONT WILL MOVE SOUTH
ACROSS THE LAKE THIS EVENING AND TONIGHT WITH WINDS TURNING
NORTHEAST AND INCREASING SHARPLY INTO THE 20-25 KT RANGE
PARTICULARLY OVER THE NORTH HALF OF THE LAKE. WINDS DIMINISH
THURSDAY..THEN TURN BACK TO THE SOUTHEAST AND INCREASE AGAIN
THURSDAY NIGHT INTO FRIDAY. BY FRIDAY...SOUTH WINDS TO 30 KT ARE
EXPECTED OVER THE NORTH HALF OF THE LAKE AND A BRIEF PERIOD OF SOUTH
GALES IS NOT OUT OF THE QUESTION. WINDS WILL REMAIN FRESH THROUGH
THE WEEKEND...TURNING NORTHWEST ON SUNDAY AS ANOTHER COLD FRONT
MOVES ACROSS THE LAKE.

BMD

&&

.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 171156
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
656 AM CDT Wed Sep 17 2014

.SHORT TERM...(Today)
ISSUED AT 237 AM CDT WED SEP 17 2014

Recently issued a Dense Fog Advisory across portions of east-central
and southeast Illinois to account for rapidly expanding dense fog.
This dense fog is forming along a northeast-southwest surface ridge
axis, in an area with near zero surface temperature/dew point
spreads and calm winds. It is not entirely clear how far north and
west of the ridge axis a dense fog threat exists, as winds are dead
calm across most of the forecast area. However, a small
temperature/dew point spread exists north/west of the current Dense
Fog Advisory area, and some mid clouds are beginning to spill across
central Illinois from a short wave moving through the plains. These
factors lead me to believe the current advisory should be sufficient.

Aside from the locally dense morning fog, the only forecast problem
for the day revolves around the precipitation threat (if any) from
the wave moving through the Plains. Some of the model guidance is
suggesting the far southern part of the forecast area may be brushed
by light rainfall later today. However, think these precipitation
forecasts are likely too far north. The model consensus has the vort
max with the short wave staying south of the forecast area, along
with the bulk of the isentropic lift ahead of the wave. These
factors, combined with the dry air mass currently in place, support
continuing with our current dry forecast for today. Temperatures
today are likely to be similar to yesterday`s. While weak low
level warm air advection will be taking place, it is likely to be
offset to some degree by additional cloud cover today.

&&

.LONG TERM...(Tonight through Tuesday)
ISSUED AT 237 AM CDT WED SEP 17 2014

High pressure over the Great Lakes to keep us in a dry east to
northeast flow into Thursday evening. After that, incoming shortwave
from the northwest comes into play. As with the daytime models, the
evening runs have continued the trend that the remnant moisture from
Odile will probably make it about as far as Missouri before shunting
southeast, so the incoming wave never really draws from it. This
lessens the threat of widespread heavy rain. The southeast half of
the CWA will likely remain dry through Saturday, while rain chances
increase across the northwest during the afternoon, and the best
chances occur Saturday night.

Sunday may be a bit of a question mark. The GFS and Canadian models
both have a rather clean frontal passage with lingering rain ending
in the morning. However, the latest ECMWF slows the front as a
surface low forms over Kansas, lingering rain across the south half
of the forecast area into Sunday evening. There may be a bit of a
feedback issue with that solution, so will maintain the dry
conditions by Sunday evening.

Rather large surface high will dominate the Midwest early next week,
with dry conditions for a few days.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
ISSUED AT 656 AM CDT WED SEP 17 2014

Patchy, mainly MVFR, early morning fog to start the day across the
central Illinois terminals. Patchy fog is likely to redevelop
again tonight toward the end of the forecast period. Otherwise,
periods of VFR cigs are expected into this afternoon, with clear
skies likely tonight. Light/variable winds with a ridge of high
pressure nearby today, will trend light/northeast for tonight.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY until 10 AM CDT this morning FOR ILZ054>057-
061>063-066>068-071>073.

&&

$$

SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...BAK







000
FXUS63 KLOT 171119
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
619 AM CDT WED SEP 17 2014

.DISCUSSION...
231 AM CDT

OVERARCHING THEME OF THE FORECAST FOR THE NEXT SEVEN DAYS IS FAIRLY
NICE EARLY FALL WEATHER WITH A DASH OF UNSEASONABLE WARMTH AND
SPLASH OF THUNDERSTORMS.

TODAY LOOKS TO BE ANOTHER GLORIOUS DAY...LIKELY A COUPLE/FEW DEGREES
WARMER THAN TUESDAY. GUIDANCE WAS A COUPLE DEGREES TOO COOL WITH
HIGHS TUESDAY AND WITH 925MB AND 850MB TEMPS PROGGED TO BE 2-3C
WARMER THAN YESTERDAY HAVE OPTED TO GO A COUPLE DEGREES ABOVE
GUIDANCE WITH HIGHS NEAR OR INTO THE LOWER 70S MOST AREAS. SOME
ACCAS AND MID LEVEL CLOUDINESS UPSTREAM ASSOCIATED WITH MID-LEVEL
WARM AIR ADVECTION COULD LEAD TO A BIT MORE CLOUDINESS THAN THE
NEARLY CLOUD FREE SKIES TUESDAY BUT STILL LOOK FOR PLENTY OF
SUNSHINE TODAY.

WEAKENING BACKDOOR COLD FRONT MOVES IN OFF THE LAKE EARLY THURSDAY
MORNING RESULTING IN SOME SLIGHTLY COOLER TEMPS THURS...ESPECIALLY
DOWNWIND OF THE LAKE WHERE NORTHEAST WINDS WILL HAVE A BETTER UMPH
BEHIND THE FRONT AND RESULT IN A GREATER LAKE INFLUENCE TO TEMPS.
WINDS BEGIN TO VEER AND SHOULD BECOMING SOUTHEASTERLY THURSDAY NIGHT
WITH WARM AIR ADVECTION GETTING UNDERWAY. WARM AIR ADVECTION GETS
GOING INTO FULL GEAR BY LATE FRIDAY AND GIVEN THE LATER ARRIVAL OF
THE TOASTIER TEMPS ITS UNCLEAR HOW MUCH WARMING WILL BE REALIZED
WITH HIGHS FRIDAY. HAVE CONSERVATIVELY BUMPED TEMPS UP INTO THE 70S
AREA WIDE...BUT PROGGED 00Z 850MB/925MB TEMPS WOULD ACTUALLY SUPPORT
TEMPS AROUND 80F. FRIDAY NIGHT LOOKS TO BE FAIRLY WARM WITH
SOUTHERLY WINDS CONTINUING...IN FACT MANY AREAS WILL SEE LOW TEMPS
FRI NIGHT WARMER THAN HIGH TEMPS WERE LAST WEEK! GUIDANCE CONTINUES
TO ADVERTISE 850MB TEMPS IN THE MID-UPPER TEENS WITH 925MB TEMPS
AROUND 20C...WHICH CLIMO SUGGESTS HIGHS WELL INTO THE 80S. HAVE
TRENDED TEMPS UPWARD SOME INTO THE LOW TO MID 80S AND WITH ENOUGH
SUNSHINE EVEN THOSE FORECAST HIGHS COULD END UP BEING A BIT TOO LOW!

COLD FRONT STILL LOOKS SLATED TO ARRIVE LATE SATURDAY WITH SHOWERS
AND THUNDERSTORMS CERTAINLY LOOKING LIKE A DECENT BET ALONG THE
FRONT. MEDIUM RANGE GUIDANCE HAS TRENDED TOWARD LESS PHASING WITH
THE NORTHERN STREAM TROUGH AND THE REMNANTS OF ODILE...SO NOT
LOOKING LIKE QUITE AS BIG OF A RAIN PRODUCER AS PREVIOUS RUNS
SUGGESTED. THE PUSH OF COLDER AIR BEHIND THE FRONT SATURDAY LOOKS TO
COME IN PHASES...WITH THE FIRST PHASE INITIALLY LOOKING LIKE MORE OF
A PUSH OF PACIFIC AIR SUNDAY BEFORE SECONDARY PUSH OF MORE
SUBSTANTIAL COLD AIR ARRIVES EARLY NEXT WEEK SENDING TEMPS DROPPING
BELOW AVERAGE AGAIN.

IZZI

&&

.AVIATION...

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

* LAKE BREEZE THIS AFTERNOON.
* COLD FRONT EARLY THURSDAY WITH POSSIBILITY OF LOWER STRATUS
  BEHIND.

BMD

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

HIGH PRESSURE WILL BE IN PLACE TODAY WITH CONTINUED LIGHT WINDS AND
PRIMARILY VFR CONDITIONS OUTSIDE OF EARLY MORNING FOG. CONFIDENCE IN
WIND DIRECTION IS LOWER MAINLY DUE TO THE OVERALL LIGHT
MAGNITUDE...BUT EXPECT A GENERALLY SOUTHWEST WIND EARLY THIS MORNING
TO GRADUALLY VEER TO NORTHWEST BY EARLY AFTERNOON...THEN A LAKE
BREEZE WILL TURN WINDS EASTERLY MID TO LATE THIS AFTERNOON.
THROUGHOUT WINDS SHOULD REMAIN LESS THAN 10 KT. MOSTLY SUNNY SKIES
WILL BE IN PLACE AGAIN TODAY WITH A FEW MORE MID AND HIGH CLOUDS AS
COMPARED TO YESTERDAY. WINDS ARE EXPECTED TO GO LIGHT AND VARIABLE
OVERNIGHT...THEN LATE TONIGHT INTO EARLY THURSDAY A COLD FRONT WILL
DROP ACROSS THE REGION TURNING WINDS BACK TO THE NORTHEAST. SOME
MODELS HINT AT THE POSSIBILITY OF SOME MVFR STRATUS COMING IN BEHIND
THE FRONT.

BMD


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

* MEDIUM-HIGH CONFIDENCE IN LAKE BREEZE TIMING TO WITHIN AN HOUR
  OR TWO.
* LOW CONFIDENCE IN CIGS THURSDAY MORNING.
* HIGH CONFIDENCE IN VFR CONDITIONS TODAY AND MOST OF TONIGHT.
* HIGH CONFIDENCE IN WINDS LESS THAN 10 KT.

BMD

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

THURSDAY NIGHT THROUGH FRIDAY...VFR
SATURDAY...CHANCE OF THUNDERSTORMS.
SUNDAY THROUGH TUESDAY...VFR.

BMD

&&

.MARINE...
222 AM CDT

AREAS OF HIGH PRESSURE LIE ACROSS THE OHIO VALLEY AND THE CANADIAN
PRAIRIES EARLY THIS MORNING WITH COLD FRONT IN BETWEEN THESE TWO
FEATURES JUST NORTH OF LAKE MICHIGAN. THIS FRONT WILL MOVE SOUTH
ACROSS THE LAKE THIS EVENING AND TONIGHT WITH WINDS TURNING
NORTHEAST AND INCREASING SHARPLY INTO THE 20-25 KT RANGE
PARTICULARLY OVER THE NORTH HALF OF THE LAKE. WINDS DIMINISH
THURSDAY..THEN TURN BACK TO THE SOUTHEAST AND INCREASE AGAIN
THURSDAY NIGHT INTO FRIDAY. BY FRIDAY...SOUTH WINDS TO 30 KT ARE
EXPECTED OVER THE NORTH HALF OF THE LAKE AND A BRIEF PERIOD OF SOUTH
GALES IS NOT OUT OF THE QUESTION. WINDS WILL REMAIN FRESH THROUGH
THE WEEKEND...TURNING NORTHWEST ON SUNDAY AS ANOTHER COLD FRONT
MOVES ACROSS THE LAKE.

BMD

&&

.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 171119
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
619 AM CDT WED SEP 17 2014

.DISCUSSION...
231 AM CDT

OVERARCHING THEME OF THE FORECAST FOR THE NEXT SEVEN DAYS IS FAIRLY
NICE EARLY FALL WEATHER WITH A DASH OF UNSEASONABLE WARMTH AND
SPLASH OF THUNDERSTORMS.

TODAY LOOKS TO BE ANOTHER GLORIOUS DAY...LIKELY A COUPLE/FEW DEGREES
WARMER THAN TUESDAY. GUIDANCE WAS A COUPLE DEGREES TOO COOL WITH
HIGHS TUESDAY AND WITH 925MB AND 850MB TEMPS PROGGED TO BE 2-3C
WARMER THAN YESTERDAY HAVE OPTED TO GO A COUPLE DEGREES ABOVE
GUIDANCE WITH HIGHS NEAR OR INTO THE LOWER 70S MOST AREAS. SOME
ACCAS AND MID LEVEL CLOUDINESS UPSTREAM ASSOCIATED WITH MID-LEVEL
WARM AIR ADVECTION COULD LEAD TO A BIT MORE CLOUDINESS THAN THE
NEARLY CLOUD FREE SKIES TUESDAY BUT STILL LOOK FOR PLENTY OF
SUNSHINE TODAY.

WEAKENING BACKDOOR COLD FRONT MOVES IN OFF THE LAKE EARLY THURSDAY
MORNING RESULTING IN SOME SLIGHTLY COOLER TEMPS THURS...ESPECIALLY
DOWNWIND OF THE LAKE WHERE NORTHEAST WINDS WILL HAVE A BETTER UMPH
BEHIND THE FRONT AND RESULT IN A GREATER LAKE INFLUENCE TO TEMPS.
WINDS BEGIN TO VEER AND SHOULD BECOMING SOUTHEASTERLY THURSDAY NIGHT
WITH WARM AIR ADVECTION GETTING UNDERWAY. WARM AIR ADVECTION GETS
GOING INTO FULL GEAR BY LATE FRIDAY AND GIVEN THE LATER ARRIVAL OF
THE TOASTIER TEMPS ITS UNCLEAR HOW MUCH WARMING WILL BE REALIZED
WITH HIGHS FRIDAY. HAVE CONSERVATIVELY BUMPED TEMPS UP INTO THE 70S
AREA WIDE...BUT PROGGED 00Z 850MB/925MB TEMPS WOULD ACTUALLY SUPPORT
TEMPS AROUND 80F. FRIDAY NIGHT LOOKS TO BE FAIRLY WARM WITH
SOUTHERLY WINDS CONTINUING...IN FACT MANY AREAS WILL SEE LOW TEMPS
FRI NIGHT WARMER THAN HIGH TEMPS WERE LAST WEEK! GUIDANCE CONTINUES
TO ADVERTISE 850MB TEMPS IN THE MID-UPPER TEENS WITH 925MB TEMPS
AROUND 20C...WHICH CLIMO SUGGESTS HIGHS WELL INTO THE 80S. HAVE
TRENDED TEMPS UPWARD SOME INTO THE LOW TO MID 80S AND WITH ENOUGH
SUNSHINE EVEN THOSE FORECAST HIGHS COULD END UP BEING A BIT TOO LOW!

COLD FRONT STILL LOOKS SLATED TO ARRIVE LATE SATURDAY WITH SHOWERS
AND THUNDERSTORMS CERTAINLY LOOKING LIKE A DECENT BET ALONG THE
FRONT. MEDIUM RANGE GUIDANCE HAS TRENDED TOWARD LESS PHASING WITH
THE NORTHERN STREAM TROUGH AND THE REMNANTS OF ODILE...SO NOT
LOOKING LIKE QUITE AS BIG OF A RAIN PRODUCER AS PREVIOUS RUNS
SUGGESTED. THE PUSH OF COLDER AIR BEHIND THE FRONT SATURDAY LOOKS TO
COME IN PHASES...WITH THE FIRST PHASE INITIALLY LOOKING LIKE MORE OF
A PUSH OF PACIFIC AIR SUNDAY BEFORE SECONDARY PUSH OF MORE
SUBSTANTIAL COLD AIR ARRIVES EARLY NEXT WEEK SENDING TEMPS DROPPING
BELOW AVERAGE AGAIN.

IZZI

&&

.AVIATION...

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

* LAKE BREEZE THIS AFTERNOON.
* COLD FRONT EARLY THURSDAY WITH POSSIBILITY OF LOWER STRATUS
  BEHIND.

BMD

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

HIGH PRESSURE WILL BE IN PLACE TODAY WITH CONTINUED LIGHT WINDS AND
PRIMARILY VFR CONDITIONS OUTSIDE OF EARLY MORNING FOG. CONFIDENCE IN
WIND DIRECTION IS LOWER MAINLY DUE TO THE OVERALL LIGHT
MAGNITUDE...BUT EXPECT A GENERALLY SOUTHWEST WIND EARLY THIS MORNING
TO GRADUALLY VEER TO NORTHWEST BY EARLY AFTERNOON...THEN A LAKE
BREEZE WILL TURN WINDS EASTERLY MID TO LATE THIS AFTERNOON.
THROUGHOUT WINDS SHOULD REMAIN LESS THAN 10 KT. MOSTLY SUNNY SKIES
WILL BE IN PLACE AGAIN TODAY WITH A FEW MORE MID AND HIGH CLOUDS AS
COMPARED TO YESTERDAY. WINDS ARE EXPECTED TO GO LIGHT AND VARIABLE
OVERNIGHT...THEN LATE TONIGHT INTO EARLY THURSDAY A COLD FRONT WILL
DROP ACROSS THE REGION TURNING WINDS BACK TO THE NORTHEAST. SOME
MODELS HINT AT THE POSSIBILITY OF SOME MVFR STRATUS COMING IN BEHIND
THE FRONT.

BMD


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

* MEDIUM-HIGH CONFIDENCE IN LAKE BREEZE TIMING TO WITHIN AN HOUR
  OR TWO.
* LOW CONFIDENCE IN CIGS THURSDAY MORNING.
* HIGH CONFIDENCE IN VFR CONDITIONS TODAY AND MOST OF TONIGHT.
* HIGH CONFIDENCE IN WINDS LESS THAN 10 KT.

BMD

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

THURSDAY NIGHT THROUGH FRIDAY...VFR
SATURDAY...CHANCE OF THUNDERSTORMS.
SUNDAY THROUGH TUESDAY...VFR.

BMD

&&

.MARINE...
222 AM CDT

AREAS OF HIGH PRESSURE LIE ACROSS THE OHIO VALLEY AND THE CANADIAN
PRAIRIES EARLY THIS MORNING WITH COLD FRONT IN BETWEEN THESE TWO
FEATURES JUST NORTH OF LAKE MICHIGAN. THIS FRONT WILL MOVE SOUTH
ACROSS THE LAKE THIS EVENING AND TONIGHT WITH WINDS TURNING
NORTHEAST AND INCREASING SHARPLY INTO THE 20-25 KT RANGE
PARTICULARLY OVER THE NORTH HALF OF THE LAKE. WINDS DIMINISH
THURSDAY..THEN TURN BACK TO THE SOUTHEAST AND INCREASE AGAIN
THURSDAY NIGHT INTO FRIDAY. BY FRIDAY...SOUTH WINDS TO 30 KT ARE
EXPECTED OVER THE NORTH HALF OF THE LAKE AND A BRIEF PERIOD OF SOUTH
GALES IS NOT OUT OF THE QUESTION. WINDS WILL REMAIN FRESH THROUGH
THE WEEKEND...TURNING NORTHWEST ON SUNDAY AS ANOTHER COLD FRONT
MOVES ACROSS THE LAKE.

BMD

&&

.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 171119
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
619 AM CDT WED SEP 17 2014

.DISCUSSION...
231 AM CDT

OVERARCHING THEME OF THE FORECAST FOR THE NEXT SEVEN DAYS IS FAIRLY
NICE EARLY FALL WEATHER WITH A DASH OF UNSEASONABLE WARMTH AND
SPLASH OF THUNDERSTORMS.

TODAY LOOKS TO BE ANOTHER GLORIOUS DAY...LIKELY A COUPLE/FEW DEGREES
WARMER THAN TUESDAY. GUIDANCE WAS A COUPLE DEGREES TOO COOL WITH
HIGHS TUESDAY AND WITH 925MB AND 850MB TEMPS PROGGED TO BE 2-3C
WARMER THAN YESTERDAY HAVE OPTED TO GO A COUPLE DEGREES ABOVE
GUIDANCE WITH HIGHS NEAR OR INTO THE LOWER 70S MOST AREAS. SOME
ACCAS AND MID LEVEL CLOUDINESS UPSTREAM ASSOCIATED WITH MID-LEVEL
WARM AIR ADVECTION COULD LEAD TO A BIT MORE CLOUDINESS THAN THE
NEARLY CLOUD FREE SKIES TUESDAY BUT STILL LOOK FOR PLENTY OF
SUNSHINE TODAY.

WEAKENING BACKDOOR COLD FRONT MOVES IN OFF THE LAKE EARLY THURSDAY
MORNING RESULTING IN SOME SLIGHTLY COOLER TEMPS THURS...ESPECIALLY
DOWNWIND OF THE LAKE WHERE NORTHEAST WINDS WILL HAVE A BETTER UMPH
BEHIND THE FRONT AND RESULT IN A GREATER LAKE INFLUENCE TO TEMPS.
WINDS BEGIN TO VEER AND SHOULD BECOMING SOUTHEASTERLY THURSDAY NIGHT
WITH WARM AIR ADVECTION GETTING UNDERWAY. WARM AIR ADVECTION GETS
GOING INTO FULL GEAR BY LATE FRIDAY AND GIVEN THE LATER ARRIVAL OF
THE TOASTIER TEMPS ITS UNCLEAR HOW MUCH WARMING WILL BE REALIZED
WITH HIGHS FRIDAY. HAVE CONSERVATIVELY BUMPED TEMPS UP INTO THE 70S
AREA WIDE...BUT PROGGED 00Z 850MB/925MB TEMPS WOULD ACTUALLY SUPPORT
TEMPS AROUND 80F. FRIDAY NIGHT LOOKS TO BE FAIRLY WARM WITH
SOUTHERLY WINDS CONTINUING...IN FACT MANY AREAS WILL SEE LOW TEMPS
FRI NIGHT WARMER THAN HIGH TEMPS WERE LAST WEEK! GUIDANCE CONTINUES
TO ADVERTISE 850MB TEMPS IN THE MID-UPPER TEENS WITH 925MB TEMPS
AROUND 20C...WHICH CLIMO SUGGESTS HIGHS WELL INTO THE 80S. HAVE
TRENDED TEMPS UPWARD SOME INTO THE LOW TO MID 80S AND WITH ENOUGH
SUNSHINE EVEN THOSE FORECAST HIGHS COULD END UP BEING A BIT TOO LOW!

COLD FRONT STILL LOOKS SLATED TO ARRIVE LATE SATURDAY WITH SHOWERS
AND THUNDERSTORMS CERTAINLY LOOKING LIKE A DECENT BET ALONG THE
FRONT. MEDIUM RANGE GUIDANCE HAS TRENDED TOWARD LESS PHASING WITH
THE NORTHERN STREAM TROUGH AND THE REMNANTS OF ODILE...SO NOT
LOOKING LIKE QUITE AS BIG OF A RAIN PRODUCER AS PREVIOUS RUNS
SUGGESTED. THE PUSH OF COLDER AIR BEHIND THE FRONT SATURDAY LOOKS TO
COME IN PHASES...WITH THE FIRST PHASE INITIALLY LOOKING LIKE MORE OF
A PUSH OF PACIFIC AIR SUNDAY BEFORE SECONDARY PUSH OF MORE
SUBSTANTIAL COLD AIR ARRIVES EARLY NEXT WEEK SENDING TEMPS DROPPING
BELOW AVERAGE AGAIN.

IZZI

&&

.AVIATION...

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

* LAKE BREEZE THIS AFTERNOON.
* COLD FRONT EARLY THURSDAY WITH POSSIBILITY OF LOWER STRATUS
  BEHIND.

BMD

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

HIGH PRESSURE WILL BE IN PLACE TODAY WITH CONTINUED LIGHT WINDS AND
PRIMARILY VFR CONDITIONS OUTSIDE OF EARLY MORNING FOG. CONFIDENCE IN
WIND DIRECTION IS LOWER MAINLY DUE TO THE OVERALL LIGHT
MAGNITUDE...BUT EXPECT A GENERALLY SOUTHWEST WIND EARLY THIS MORNING
TO GRADUALLY VEER TO NORTHWEST BY EARLY AFTERNOON...THEN A LAKE
BREEZE WILL TURN WINDS EASTERLY MID TO LATE THIS AFTERNOON.
THROUGHOUT WINDS SHOULD REMAIN LESS THAN 10 KT. MOSTLY SUNNY SKIES
WILL BE IN PLACE AGAIN TODAY WITH A FEW MORE MID AND HIGH CLOUDS AS
COMPARED TO YESTERDAY. WINDS ARE EXPECTED TO GO LIGHT AND VARIABLE
OVERNIGHT...THEN LATE TONIGHT INTO EARLY THURSDAY A COLD FRONT WILL
DROP ACROSS THE REGION TURNING WINDS BACK TO THE NORTHEAST. SOME
MODELS HINT AT THE POSSIBILITY OF SOME MVFR STRATUS COMING IN BEHIND
THE FRONT.

BMD


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

* MEDIUM-HIGH CONFIDENCE IN LAKE BREEZE TIMING TO WITHIN AN HOUR
  OR TWO.
* LOW CONFIDENCE IN CIGS THURSDAY MORNING.
* HIGH CONFIDENCE IN VFR CONDITIONS TODAY AND MOST OF TONIGHT.
* HIGH CONFIDENCE IN WINDS LESS THAN 10 KT.

BMD

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

THURSDAY NIGHT THROUGH FRIDAY...VFR
SATURDAY...CHANCE OF THUNDERSTORMS.
SUNDAY THROUGH TUESDAY...VFR.

BMD

&&

.MARINE...
222 AM CDT

AREAS OF HIGH PRESSURE LIE ACROSS THE OHIO VALLEY AND THE CANADIAN
PRAIRIES EARLY THIS MORNING WITH COLD FRONT IN BETWEEN THESE TWO
FEATURES JUST NORTH OF LAKE MICHIGAN. THIS FRONT WILL MOVE SOUTH
ACROSS THE LAKE THIS EVENING AND TONIGHT WITH WINDS TURNING
NORTHEAST AND INCREASING SHARPLY INTO THE 20-25 KT RANGE
PARTICULARLY OVER THE NORTH HALF OF THE LAKE. WINDS DIMINISH
THURSDAY..THEN TURN BACK TO THE SOUTHEAST AND INCREASE AGAIN
THURSDAY NIGHT INTO FRIDAY. BY FRIDAY...SOUTH WINDS TO 30 KT ARE
EXPECTED OVER THE NORTH HALF OF THE LAKE AND A BRIEF PERIOD OF SOUTH
GALES IS NOT OUT OF THE QUESTION. WINDS WILL REMAIN FRESH THROUGH
THE WEEKEND...TURNING NORTHWEST ON SUNDAY AS ANOTHER COLD FRONT
MOVES ACROSS THE LAKE.

BMD

&&

.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 171119
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
619 AM CDT WED SEP 17 2014

.DISCUSSION...
231 AM CDT

OVERARCHING THEME OF THE FORECAST FOR THE NEXT SEVEN DAYS IS FAIRLY
NICE EARLY FALL WEATHER WITH A DASH OF UNSEASONABLE WARMTH AND
SPLASH OF THUNDERSTORMS.

TODAY LOOKS TO BE ANOTHER GLORIOUS DAY...LIKELY A COUPLE/FEW DEGREES
WARMER THAN TUESDAY. GUIDANCE WAS A COUPLE DEGREES TOO COOL WITH
HIGHS TUESDAY AND WITH 925MB AND 850MB TEMPS PROGGED TO BE 2-3C
WARMER THAN YESTERDAY HAVE OPTED TO GO A COUPLE DEGREES ABOVE
GUIDANCE WITH HIGHS NEAR OR INTO THE LOWER 70S MOST AREAS. SOME
ACCAS AND MID LEVEL CLOUDINESS UPSTREAM ASSOCIATED WITH MID-LEVEL
WARM AIR ADVECTION COULD LEAD TO A BIT MORE CLOUDINESS THAN THE
NEARLY CLOUD FREE SKIES TUESDAY BUT STILL LOOK FOR PLENTY OF
SUNSHINE TODAY.

WEAKENING BACKDOOR COLD FRONT MOVES IN OFF THE LAKE EARLY THURSDAY
MORNING RESULTING IN SOME SLIGHTLY COOLER TEMPS THURS...ESPECIALLY
DOWNWIND OF THE LAKE WHERE NORTHEAST WINDS WILL HAVE A BETTER UMPH
BEHIND THE FRONT AND RESULT IN A GREATER LAKE INFLUENCE TO TEMPS.
WINDS BEGIN TO VEER AND SHOULD BECOMING SOUTHEASTERLY THURSDAY NIGHT
WITH WARM AIR ADVECTION GETTING UNDERWAY. WARM AIR ADVECTION GETS
GOING INTO FULL GEAR BY LATE FRIDAY AND GIVEN THE LATER ARRIVAL OF
THE TOASTIER TEMPS ITS UNCLEAR HOW MUCH WARMING WILL BE REALIZED
WITH HIGHS FRIDAY. HAVE CONSERVATIVELY BUMPED TEMPS UP INTO THE 70S
AREA WIDE...BUT PROGGED 00Z 850MB/925MB TEMPS WOULD ACTUALLY SUPPORT
TEMPS AROUND 80F. FRIDAY NIGHT LOOKS TO BE FAIRLY WARM WITH
SOUTHERLY WINDS CONTINUING...IN FACT MANY AREAS WILL SEE LOW TEMPS
FRI NIGHT WARMER THAN HIGH TEMPS WERE LAST WEEK! GUIDANCE CONTINUES
TO ADVERTISE 850MB TEMPS IN THE MID-UPPER TEENS WITH 925MB TEMPS
AROUND 20C...WHICH CLIMO SUGGESTS HIGHS WELL INTO THE 80S. HAVE
TRENDED TEMPS UPWARD SOME INTO THE LOW TO MID 80S AND WITH ENOUGH
SUNSHINE EVEN THOSE FORECAST HIGHS COULD END UP BEING A BIT TOO LOW!

COLD FRONT STILL LOOKS SLATED TO ARRIVE LATE SATURDAY WITH SHOWERS
AND THUNDERSTORMS CERTAINLY LOOKING LIKE A DECENT BET ALONG THE
FRONT. MEDIUM RANGE GUIDANCE HAS TRENDED TOWARD LESS PHASING WITH
THE NORTHERN STREAM TROUGH AND THE REMNANTS OF ODILE...SO NOT
LOOKING LIKE QUITE AS BIG OF A RAIN PRODUCER AS PREVIOUS RUNS
SUGGESTED. THE PUSH OF COLDER AIR BEHIND THE FRONT SATURDAY LOOKS TO
COME IN PHASES...WITH THE FIRST PHASE INITIALLY LOOKING LIKE MORE OF
A PUSH OF PACIFIC AIR SUNDAY BEFORE SECONDARY PUSH OF MORE
SUBSTANTIAL COLD AIR ARRIVES EARLY NEXT WEEK SENDING TEMPS DROPPING
BELOW AVERAGE AGAIN.

IZZI

&&

.AVIATION...

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

* LAKE BREEZE THIS AFTERNOON.
* COLD FRONT EARLY THURSDAY WITH POSSIBILITY OF LOWER STRATUS
  BEHIND.

BMD

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

HIGH PRESSURE WILL BE IN PLACE TODAY WITH CONTINUED LIGHT WINDS AND
PRIMARILY VFR CONDITIONS OUTSIDE OF EARLY MORNING FOG. CONFIDENCE IN
WIND DIRECTION IS LOWER MAINLY DUE TO THE OVERALL LIGHT
MAGNITUDE...BUT EXPECT A GENERALLY SOUTHWEST WIND EARLY THIS MORNING
TO GRADUALLY VEER TO NORTHWEST BY EARLY AFTERNOON...THEN A LAKE
BREEZE WILL TURN WINDS EASTERLY MID TO LATE THIS AFTERNOON.
THROUGHOUT WINDS SHOULD REMAIN LESS THAN 10 KT. MOSTLY SUNNY SKIES
WILL BE IN PLACE AGAIN TODAY WITH A FEW MORE MID AND HIGH CLOUDS AS
COMPARED TO YESTERDAY. WINDS ARE EXPECTED TO GO LIGHT AND VARIABLE
OVERNIGHT...THEN LATE TONIGHT INTO EARLY THURSDAY A COLD FRONT WILL
DROP ACROSS THE REGION TURNING WINDS BACK TO THE NORTHEAST. SOME
MODELS HINT AT THE POSSIBILITY OF SOME MVFR STRATUS COMING IN BEHIND
THE FRONT.

BMD


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

* MEDIUM-HIGH CONFIDENCE IN LAKE BREEZE TIMING TO WITHIN AN HOUR
  OR TWO.
* LOW CONFIDENCE IN CIGS THURSDAY MORNING.
* HIGH CONFIDENCE IN VFR CONDITIONS TODAY AND MOST OF TONIGHT.
* HIGH CONFIDENCE IN WINDS LESS THAN 10 KT.

BMD

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

THURSDAY NIGHT THROUGH FRIDAY...VFR
SATURDAY...CHANCE OF THUNDERSTORMS.
SUNDAY THROUGH TUESDAY...VFR.

BMD

&&

.MARINE...
222 AM CDT

AREAS OF HIGH PRESSURE LIE ACROSS THE OHIO VALLEY AND THE CANADIAN
PRAIRIES EARLY THIS MORNING WITH COLD FRONT IN BETWEEN THESE TWO
FEATURES JUST NORTH OF LAKE MICHIGAN. THIS FRONT WILL MOVE SOUTH
ACROSS THE LAKE THIS EVENING AND TONIGHT WITH WINDS TURNING
NORTHEAST AND INCREASING SHARPLY INTO THE 20-25 KT RANGE
PARTICULARLY OVER THE NORTH HALF OF THE LAKE. WINDS DIMINISH
THURSDAY..THEN TURN BACK TO THE SOUTHEAST AND INCREASE AGAIN
THURSDAY NIGHT INTO FRIDAY. BY FRIDAY...SOUTH WINDS TO 30 KT ARE
EXPECTED OVER THE NORTH HALF OF THE LAKE AND A BRIEF PERIOD OF SOUTH
GALES IS NOT OUT OF THE QUESTION. WINDS WILL REMAIN FRESH THROUGH
THE WEEKEND...TURNING NORTHWEST ON SUNDAY AS ANOTHER COLD FRONT
MOVES ACROSS THE LAKE.

BMD

&&

.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 170906
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
406 AM CDT WED SEP 17 2014

.DISCUSSION...
231 AM CDT

OVERARCHING THEME OF THE FORECAST FOR THE NEXT SEVEN DAYS IS FAIRLY
NICE EARLY FALL WEATHER WITH A DASH OF UNSEASONABLE WARMTH AND
SPLASH OF THUNDERSTORMS.

TODAY LOOKS TO BE ANOTHER GLORIOUS DAY...LIKELY A COUPLE/FEW DEGREES
WARMER THAN TUESDAY. GUIDANCE WAS A COUPLE DEGREES TOO COOL WITH
HIGHS TUESDAY AND WITH 925MB AND 850MB TEMPS PROGGED TO BE 2-3C
WARMER THAN YESTERDAY HAVE OPTED TO GO A COUPLE DEGREES ABOVE
GUIDANCE WITH HIGHS NEAR OR INTO THE LOWER 70S MOST AREAS. SOME
ACCAS AND MID LEVEL CLOUDINESS UPSTREAM ASSOCIATED WITH MID-LEVEL
WARM AIR ADVECTION COULD LEAD TO A BIT MORE CLOUDINESS THAN THE
NEARLY CLOUD FREE SKIES TUESDAY BUT STILL LOOK FOR PLENTY OF
SUNSHINE TODAY.

WEAKENING BACKDOOR COLD FRONT MOVES IN OFF THE LAKE EARLY THURSDAY
MORNING RESULTING IN SOME SLIGHTLY COOLER TEMPS THURS...ESPECIALLY
DOWNWIND OF THE LAKE WHERE NORTHEAST WINDS WILL HAVE A BETTER UMPH
BEHIND THE FRONT AND RESULT IN A GREATER LAKE INFLUENCE TO TEMPS.
WINDS BEGIN TO VEER AND SHOULD BECOMING SOUTHEASTERLY THURSDAY NIGHT
WITH WARM AIR ADVECTION GETTING UNDERWAY. WARM AIR ADVECTION GETS
GOING INTO FULL GEAR BY LATE FRIDAY AND GIVEN THE LATER ARRIVAL OF
THE TOASTIER TEMPS ITS UNCLEAR HOW MUCH WARMING WILL BE REALIZED
WITH HIGHS FRIDAY. HAVE CONSERVATIVELY BUMPED TEMPS UP INTO THE 70S
AREA WIDE...BUT PROGGED 00Z 850MB/925MB TEMPS WOULD ACTUALLY SUPPORT
TEMPS AROUND 80F. FRIDAY NIGHT LOOKS TO BE FAIRLY WARM WITH
SOUTHERLY WINDS CONTINUING...IN FACT MANY AREAS WILL SEE LOW TEMPS
FRI NIGHT WARMER THAN HIGH TEMPS WERE LAST WEEK! GUIDANCE CONTINUES
TO ADVERTISE 850MB TEMPS IN THE MID-UPPER TEENS WITH 925MB TEMPS
AROUND 20C...WHICH CLIMO SUGGESTS HIGHS WELL INTO THE 80S. HAVE
TRENDED TEMPS UPWARD SOME INTO THE LOW TO MID 80S AND WITH ENOUGH
SUNSHINE EVEN THOSE FORECAST HIGHS COULD END UP BEING A BIT TOO LOW!

COLD FRONT STILL LOOKS SLATED TO ARRIVE LATE SATURDAY WITH SHOWERS
AND THUNDERSTORMS CERTAINLY LOOKING LIKE A DECENT BET ALONG THE
FRONT. MEDIUM RANGE GUIDANCE HAS TRENDED TOWARD LESS PHASING WITH
THE NORTHERN STREAM TROUGH AND THE REMNANTS OF ODILE...SO NOT
LOOKING LIKE QUITE AS BIG OF A RAIN PRODUCER AS PREVIOUS RUNS
SUGGESTED. THE PUSH OF COLDER AIR BEHIND THE FRONT SATURDAY LOOKS TO
COME IN PHASES...WITH THE FIRST PHASE INITIALLY LOOKING LIKE MORE OF
A PUSH OF PACIFIC AIR SUNDAY BEFORE SECONDARY PUSH OF MORE
SUBSTANTIAL COLD AIR ARRIVES EARLY NEXT WEEK SENDING TEMPS DROPPING
BELOW AVERAGE AGAIN.

IZZI

&&

.AVIATION...

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

* LAKE BREEZE WEDNESDAY AFTERNOON.

BMD

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

ANOTHER QUIET WEATHER DAY IS ON TAP FOR THE REGION WITH HIGH
PRESSURE CENTERED SOUTH OF THE AREA PROVIDING CONTINUED LIGHT FLOW
AND PRIMARILY VFR CONDITIONS OUTSIDE OF SOME PATCHY FOG. FOG IS
EXPECTED TO STAY SOUTH OF THE TERMINALS TONIGHT. A FEW MID LEVEL
CLOUDS MAY DEVELOP MIDDAY WEDNESDAY. A LAKE BREEZE IS ALSO EXPECTED
TO DEVELOP AND SHOULD PUSH ACROSS THE TERMINALS EARLY TO MID
AFTERNOON TURNING WINDS EASTERLY AND BRIEFLY INCREASING SPEEDS INTO
THE 7-9 KT RANGE.

BMD

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

* MEDIUM-HIGH ON LAKE BREEZE TO WITHIN A COUPLE HOURS.
* HIGH ON REMAINING FORECAST ELEMENTS.

BMD

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

* THURSDAY AND FRIDAY...DRY/VFR.
* SATURDAY...CHANCE TSRA. GUSTY SOUTHWEST WINDS.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY...DRY/VFR.

&&

.MARINE...
222 AM CDT

AREAS OF HIGH PRESSURE LIE ACROSS THE OHIO VALLEY AND THE CANADIAN
PRAIRIES EARLY THIS MORNING WITH COLD FRONT IN BETWEEN THESE TWO
FEATURES JUST NORTH OF LAKE MICHIGAN. THIS FRONT WILL MOVE SOUTH
ACROSS THE LAKE THIS EVENING AND TONIGHT WITH WINDS TURNING
NORTHEAST AND INCREASING SHARPLY INTO THE 20-25 KT RANGE
PARTICULARLY OVER THE NORTH HALF OF THE LAKE. WINDS DIMINISH
THURSDAY..THEN TURN BACK TO THE SOUTHEAST AND INCREASE AGAIN
THURSDAY NIGHT INTO FRIDAY. BY FRIDAY...SOUTH WINDS TO 30 KT ARE
EXPECTED OVER THE NORTH HALF OF THE LAKE AND A BRIEF PERIOD OF SOUTH
GALES IS NOT OUT OF THE QUESTION. WINDS WILL REMAIN FRESH THROUGH
THE WEEKEND...TURNING NORTHWEST ON SUNDAY AS ANOTHER COLD FRONT
MOVES ACROSS THE LAKE.

BMD

&&

.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 170906
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
406 AM CDT WED SEP 17 2014

.DISCUSSION...
231 AM CDT

OVERARCHING THEME OF THE FORECAST FOR THE NEXT SEVEN DAYS IS FAIRLY
NICE EARLY FALL WEATHER WITH A DASH OF UNSEASONABLE WARMTH AND
SPLASH OF THUNDERSTORMS.

TODAY LOOKS TO BE ANOTHER GLORIOUS DAY...LIKELY A COUPLE/FEW DEGREES
WARMER THAN TUESDAY. GUIDANCE WAS A COUPLE DEGREES TOO COOL WITH
HIGHS TUESDAY AND WITH 925MB AND 850MB TEMPS PROGGED TO BE 2-3C
WARMER THAN YESTERDAY HAVE OPTED TO GO A COUPLE DEGREES ABOVE
GUIDANCE WITH HIGHS NEAR OR INTO THE LOWER 70S MOST AREAS. SOME
ACCAS AND MID LEVEL CLOUDINESS UPSTREAM ASSOCIATED WITH MID-LEVEL
WARM AIR ADVECTION COULD LEAD TO A BIT MORE CLOUDINESS THAN THE
NEARLY CLOUD FREE SKIES TUESDAY BUT STILL LOOK FOR PLENTY OF
SUNSHINE TODAY.

WEAKENING BACKDOOR COLD FRONT MOVES IN OFF THE LAKE EARLY THURSDAY
MORNING RESULTING IN SOME SLIGHTLY COOLER TEMPS THURS...ESPECIALLY
DOWNWIND OF THE LAKE WHERE NORTHEAST WINDS WILL HAVE A BETTER UMPH
BEHIND THE FRONT AND RESULT IN A GREATER LAKE INFLUENCE TO TEMPS.
WINDS BEGIN TO VEER AND SHOULD BECOMING SOUTHEASTERLY THURSDAY NIGHT
WITH WARM AIR ADVECTION GETTING UNDERWAY. WARM AIR ADVECTION GETS
GOING INTO FULL GEAR BY LATE FRIDAY AND GIVEN THE LATER ARRIVAL OF
THE TOASTIER TEMPS ITS UNCLEAR HOW MUCH WARMING WILL BE REALIZED
WITH HIGHS FRIDAY. HAVE CONSERVATIVELY BUMPED TEMPS UP INTO THE 70S
AREA WIDE...BUT PROGGED 00Z 850MB/925MB TEMPS WOULD ACTUALLY SUPPORT
TEMPS AROUND 80F. FRIDAY NIGHT LOOKS TO BE FAIRLY WARM WITH
SOUTHERLY WINDS CONTINUING...IN FACT MANY AREAS WILL SEE LOW TEMPS
FRI NIGHT WARMER THAN HIGH TEMPS WERE LAST WEEK! GUIDANCE CONTINUES
TO ADVERTISE 850MB TEMPS IN THE MID-UPPER TEENS WITH 925MB TEMPS
AROUND 20C...WHICH CLIMO SUGGESTS HIGHS WELL INTO THE 80S. HAVE
TRENDED TEMPS UPWARD SOME INTO THE LOW TO MID 80S AND WITH ENOUGH
SUNSHINE EVEN THOSE FORECAST HIGHS COULD END UP BEING A BIT TOO LOW!

COLD FRONT STILL LOOKS SLATED TO ARRIVE LATE SATURDAY WITH SHOWERS
AND THUNDERSTORMS CERTAINLY LOOKING LIKE A DECENT BET ALONG THE
FRONT. MEDIUM RANGE GUIDANCE HAS TRENDED TOWARD LESS PHASING WITH
THE NORTHERN STREAM TROUGH AND THE REMNANTS OF ODILE...SO NOT
LOOKING LIKE QUITE AS BIG OF A RAIN PRODUCER AS PREVIOUS RUNS
SUGGESTED. THE PUSH OF COLDER AIR BEHIND THE FRONT SATURDAY LOOKS TO
COME IN PHASES...WITH THE FIRST PHASE INITIALLY LOOKING LIKE MORE OF
A PUSH OF PACIFIC AIR SUNDAY BEFORE SECONDARY PUSH OF MORE
SUBSTANTIAL COLD AIR ARRIVES EARLY NEXT WEEK SENDING TEMPS DROPPING
BELOW AVERAGE AGAIN.

IZZI

&&

.AVIATION...

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

* LAKE BREEZE WEDNESDAY AFTERNOON.

BMD

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

ANOTHER QUIET WEATHER DAY IS ON TAP FOR THE REGION WITH HIGH
PRESSURE CENTERED SOUTH OF THE AREA PROVIDING CONTINUED LIGHT FLOW
AND PRIMARILY VFR CONDITIONS OUTSIDE OF SOME PATCHY FOG. FOG IS
EXPECTED TO STAY SOUTH OF THE TERMINALS TONIGHT. A FEW MID LEVEL
CLOUDS MAY DEVELOP MIDDAY WEDNESDAY. A LAKE BREEZE IS ALSO EXPECTED
TO DEVELOP AND SHOULD PUSH ACROSS THE TERMINALS EARLY TO MID
AFTERNOON TURNING WINDS EASTERLY AND BRIEFLY INCREASING SPEEDS INTO
THE 7-9 KT RANGE.

BMD

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

* MEDIUM-HIGH ON LAKE BREEZE TO WITHIN A COUPLE HOURS.
* HIGH ON REMAINING FORECAST ELEMENTS.

BMD

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

* THURSDAY AND FRIDAY...DRY/VFR.
* SATURDAY...CHANCE TSRA. GUSTY SOUTHWEST WINDS.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY...DRY/VFR.

&&

.MARINE...
222 AM CDT

AREAS OF HIGH PRESSURE LIE ACROSS THE OHIO VALLEY AND THE CANADIAN
PRAIRIES EARLY THIS MORNING WITH COLD FRONT IN BETWEEN THESE TWO
FEATURES JUST NORTH OF LAKE MICHIGAN. THIS FRONT WILL MOVE SOUTH
ACROSS THE LAKE THIS EVENING AND TONIGHT WITH WINDS TURNING
NORTHEAST AND INCREASING SHARPLY INTO THE 20-25 KT RANGE
PARTICULARLY OVER THE NORTH HALF OF THE LAKE. WINDS DIMINISH
THURSDAY..THEN TURN BACK TO THE SOUTHEAST AND INCREASE AGAIN
THURSDAY NIGHT INTO FRIDAY. BY FRIDAY...SOUTH WINDS TO 30 KT ARE
EXPECTED OVER THE NORTH HALF OF THE LAKE AND A BRIEF PERIOD OF SOUTH
GALES IS NOT OUT OF THE QUESTION. WINDS WILL REMAIN FRESH THROUGH
THE WEEKEND...TURNING NORTHWEST ON SUNDAY AS ANOTHER COLD FRONT
MOVES ACROSS THE LAKE.

BMD

&&

.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 170906
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
406 AM CDT WED SEP 17 2014

.DISCUSSION...
231 AM CDT

OVERARCHING THEME OF THE FORECAST FOR THE NEXT SEVEN DAYS IS FAIRLY
NICE EARLY FALL WEATHER WITH A DASH OF UNSEASONABLE WARMTH AND
SPLASH OF THUNDERSTORMS.

TODAY LOOKS TO BE ANOTHER GLORIOUS DAY...LIKELY A COUPLE/FEW DEGREES
WARMER THAN TUESDAY. GUIDANCE WAS A COUPLE DEGREES TOO COOL WITH
HIGHS TUESDAY AND WITH 925MB AND 850MB TEMPS PROGGED TO BE 2-3C
WARMER THAN YESTERDAY HAVE OPTED TO GO A COUPLE DEGREES ABOVE
GUIDANCE WITH HIGHS NEAR OR INTO THE LOWER 70S MOST AREAS. SOME
ACCAS AND MID LEVEL CLOUDINESS UPSTREAM ASSOCIATED WITH MID-LEVEL
WARM AIR ADVECTION COULD LEAD TO A BIT MORE CLOUDINESS THAN THE
NEARLY CLOUD FREE SKIES TUESDAY BUT STILL LOOK FOR PLENTY OF
SUNSHINE TODAY.

WEAKENING BACKDOOR COLD FRONT MOVES IN OFF THE LAKE EARLY THURSDAY
MORNING RESULTING IN SOME SLIGHTLY COOLER TEMPS THURS...ESPECIALLY
DOWNWIND OF THE LAKE WHERE NORTHEAST WINDS WILL HAVE A BETTER UMPH
BEHIND THE FRONT AND RESULT IN A GREATER LAKE INFLUENCE TO TEMPS.
WINDS BEGIN TO VEER AND SHOULD BECOMING SOUTHEASTERLY THURSDAY NIGHT
WITH WARM AIR ADVECTION GETTING UNDERWAY. WARM AIR ADVECTION GETS
GOING INTO FULL GEAR BY LATE FRIDAY AND GIVEN THE LATER ARRIVAL OF
THE TOASTIER TEMPS ITS UNCLEAR HOW MUCH WARMING WILL BE REALIZED
WITH HIGHS FRIDAY. HAVE CONSERVATIVELY BUMPED TEMPS UP INTO THE 70S
AREA WIDE...BUT PROGGED 00Z 850MB/925MB TEMPS WOULD ACTUALLY SUPPORT
TEMPS AROUND 80F. FRIDAY NIGHT LOOKS TO BE FAIRLY WARM WITH
SOUTHERLY WINDS CONTINUING...IN FACT MANY AREAS WILL SEE LOW TEMPS
FRI NIGHT WARMER THAN HIGH TEMPS WERE LAST WEEK! GUIDANCE CONTINUES
TO ADVERTISE 850MB TEMPS IN THE MID-UPPER TEENS WITH 925MB TEMPS
AROUND 20C...WHICH CLIMO SUGGESTS HIGHS WELL INTO THE 80S. HAVE
TRENDED TEMPS UPWARD SOME INTO THE LOW TO MID 80S AND WITH ENOUGH
SUNSHINE EVEN THOSE FORECAST HIGHS COULD END UP BEING A BIT TOO LOW!

COLD FRONT STILL LOOKS SLATED TO ARRIVE LATE SATURDAY WITH SHOWERS
AND THUNDERSTORMS CERTAINLY LOOKING LIKE A DECENT BET ALONG THE
FRONT. MEDIUM RANGE GUIDANCE HAS TRENDED TOWARD LESS PHASING WITH
THE NORTHERN STREAM TROUGH AND THE REMNANTS OF ODILE...SO NOT
LOOKING LIKE QUITE AS BIG OF A RAIN PRODUCER AS PREVIOUS RUNS
SUGGESTED. THE PUSH OF COLDER AIR BEHIND THE FRONT SATURDAY LOOKS TO
COME IN PHASES...WITH THE FIRST PHASE INITIALLY LOOKING LIKE MORE OF
A PUSH OF PACIFIC AIR SUNDAY BEFORE SECONDARY PUSH OF MORE
SUBSTANTIAL COLD AIR ARRIVES EARLY NEXT WEEK SENDING TEMPS DROPPING
BELOW AVERAGE AGAIN.

IZZI

&&

.AVIATION...

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

* LAKE BREEZE WEDNESDAY AFTERNOON.

BMD

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

ANOTHER QUIET WEATHER DAY IS ON TAP FOR THE REGION WITH HIGH
PRESSURE CENTERED SOUTH OF THE AREA PROVIDING CONTINUED LIGHT FLOW
AND PRIMARILY VFR CONDITIONS OUTSIDE OF SOME PATCHY FOG. FOG IS
EXPECTED TO STAY SOUTH OF THE TERMINALS TONIGHT. A FEW MID LEVEL
CLOUDS MAY DEVELOP MIDDAY WEDNESDAY. A LAKE BREEZE IS ALSO EXPECTED
TO DEVELOP AND SHOULD PUSH ACROSS THE TERMINALS EARLY TO MID
AFTERNOON TURNING WINDS EASTERLY AND BRIEFLY INCREASING SPEEDS INTO
THE 7-9 KT RANGE.

BMD

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

* MEDIUM-HIGH ON LAKE BREEZE TO WITHIN A COUPLE HOURS.
* HIGH ON REMAINING FORECAST ELEMENTS.

BMD

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

* THURSDAY AND FRIDAY...DRY/VFR.
* SATURDAY...CHANCE TSRA. GUSTY SOUTHWEST WINDS.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY...DRY/VFR.

&&

.MARINE...
222 AM CDT

AREAS OF HIGH PRESSURE LIE ACROSS THE OHIO VALLEY AND THE CANADIAN
PRAIRIES EARLY THIS MORNING WITH COLD FRONT IN BETWEEN THESE TWO
FEATURES JUST NORTH OF LAKE MICHIGAN. THIS FRONT WILL MOVE SOUTH
ACROSS THE LAKE THIS EVENING AND TONIGHT WITH WINDS TURNING
NORTHEAST AND INCREASING SHARPLY INTO THE 20-25 KT RANGE
PARTICULARLY OVER THE NORTH HALF OF THE LAKE. WINDS DIMINISH
THURSDAY..THEN TURN BACK TO THE SOUTHEAST AND INCREASE AGAIN
THURSDAY NIGHT INTO FRIDAY. BY FRIDAY...SOUTH WINDS TO 30 KT ARE
EXPECTED OVER THE NORTH HALF OF THE LAKE AND A BRIEF PERIOD OF SOUTH
GALES IS NOT OUT OF THE QUESTION. WINDS WILL REMAIN FRESH THROUGH
THE WEEKEND...TURNING NORTHWEST ON SUNDAY AS ANOTHER COLD FRONT
MOVES ACROSS THE LAKE.

BMD

&&

.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 170906
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
406 AM CDT WED SEP 17 2014

.DISCUSSION...
231 AM CDT

OVERARCHING THEME OF THE FORECAST FOR THE NEXT SEVEN DAYS IS FAIRLY
NICE EARLY FALL WEATHER WITH A DASH OF UNSEASONABLE WARMTH AND
SPLASH OF THUNDERSTORMS.

TODAY LOOKS TO BE ANOTHER GLORIOUS DAY...LIKELY A COUPLE/FEW DEGREES
WARMER THAN TUESDAY. GUIDANCE WAS A COUPLE DEGREES TOO COOL WITH
HIGHS TUESDAY AND WITH 925MB AND 850MB TEMPS PROGGED TO BE 2-3C
WARMER THAN YESTERDAY HAVE OPTED TO GO A COUPLE DEGREES ABOVE
GUIDANCE WITH HIGHS NEAR OR INTO THE LOWER 70S MOST AREAS. SOME
ACCAS AND MID LEVEL CLOUDINESS UPSTREAM ASSOCIATED WITH MID-LEVEL
WARM AIR ADVECTION COULD LEAD TO A BIT MORE CLOUDINESS THAN THE
NEARLY CLOUD FREE SKIES TUESDAY BUT STILL LOOK FOR PLENTY OF
SUNSHINE TODAY.

WEAKENING BACKDOOR COLD FRONT MOVES IN OFF THE LAKE EARLY THURSDAY
MORNING RESULTING IN SOME SLIGHTLY COOLER TEMPS THURS...ESPECIALLY
DOWNWIND OF THE LAKE WHERE NORTHEAST WINDS WILL HAVE A BETTER UMPH
BEHIND THE FRONT AND RESULT IN A GREATER LAKE INFLUENCE TO TEMPS.
WINDS BEGIN TO VEER AND SHOULD BECOMING SOUTHEASTERLY THURSDAY NIGHT
WITH WARM AIR ADVECTION GETTING UNDERWAY. WARM AIR ADVECTION GETS
GOING INTO FULL GEAR BY LATE FRIDAY AND GIVEN THE LATER ARRIVAL OF
THE TOASTIER TEMPS ITS UNCLEAR HOW MUCH WARMING WILL BE REALIZED
WITH HIGHS FRIDAY. HAVE CONSERVATIVELY BUMPED TEMPS UP INTO THE 70S
AREA WIDE...BUT PROGGED 00Z 850MB/925MB TEMPS WOULD ACTUALLY SUPPORT
TEMPS AROUND 80F. FRIDAY NIGHT LOOKS TO BE FAIRLY WARM WITH
SOUTHERLY WINDS CONTINUING...IN FACT MANY AREAS WILL SEE LOW TEMPS
FRI NIGHT WARMER THAN HIGH TEMPS WERE LAST WEEK! GUIDANCE CONTINUES
TO ADVERTISE 850MB TEMPS IN THE MID-UPPER TEENS WITH 925MB TEMPS
AROUND 20C...WHICH CLIMO SUGGESTS HIGHS WELL INTO THE 80S. HAVE
TRENDED TEMPS UPWARD SOME INTO THE LOW TO MID 80S AND WITH ENOUGH
SUNSHINE EVEN THOSE FORECAST HIGHS COULD END UP BEING A BIT TOO LOW!

COLD FRONT STILL LOOKS SLATED TO ARRIVE LATE SATURDAY WITH SHOWERS
AND THUNDERSTORMS CERTAINLY LOOKING LIKE A DECENT BET ALONG THE
FRONT. MEDIUM RANGE GUIDANCE HAS TRENDED TOWARD LESS PHASING WITH
THE NORTHERN STREAM TROUGH AND THE REMNANTS OF ODILE...SO NOT
LOOKING LIKE QUITE AS BIG OF A RAIN PRODUCER AS PREVIOUS RUNS
SUGGESTED. THE PUSH OF COLDER AIR BEHIND THE FRONT SATURDAY LOOKS TO
COME IN PHASES...WITH THE FIRST PHASE INITIALLY LOOKING LIKE MORE OF
A PUSH OF PACIFIC AIR SUNDAY BEFORE SECONDARY PUSH OF MORE
SUBSTANTIAL COLD AIR ARRIVES EARLY NEXT WEEK SENDING TEMPS DROPPING
BELOW AVERAGE AGAIN.

IZZI

&&

.AVIATION...

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

* LAKE BREEZE WEDNESDAY AFTERNOON.

BMD

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

ANOTHER QUIET WEATHER DAY IS ON TAP FOR THE REGION WITH HIGH
PRESSURE CENTERED SOUTH OF THE AREA PROVIDING CONTINUED LIGHT FLOW
AND PRIMARILY VFR CONDITIONS OUTSIDE OF SOME PATCHY FOG. FOG IS
EXPECTED TO STAY SOUTH OF THE TERMINALS TONIGHT. A FEW MID LEVEL
CLOUDS MAY DEVELOP MIDDAY WEDNESDAY. A LAKE BREEZE IS ALSO EXPECTED
TO DEVELOP AND SHOULD PUSH ACROSS THE TERMINALS EARLY TO MID
AFTERNOON TURNING WINDS EASTERLY AND BRIEFLY INCREASING SPEEDS INTO
THE 7-9 KT RANGE.

BMD

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

* MEDIUM-HIGH ON LAKE BREEZE TO WITHIN A COUPLE HOURS.
* HIGH ON REMAINING FORECAST ELEMENTS.

BMD

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

* THURSDAY AND FRIDAY...DRY/VFR.
* SATURDAY...CHANCE TSRA. GUSTY SOUTHWEST WINDS.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY...DRY/VFR.

&&

.MARINE...
222 AM CDT

AREAS OF HIGH PRESSURE LIE ACROSS THE OHIO VALLEY AND THE CANADIAN
PRAIRIES EARLY THIS MORNING WITH COLD FRONT IN BETWEEN THESE TWO
FEATURES JUST NORTH OF LAKE MICHIGAN. THIS FRONT WILL MOVE SOUTH
ACROSS THE LAKE THIS EVENING AND TONIGHT WITH WINDS TURNING
NORTHEAST AND INCREASING SHARPLY INTO THE 20-25 KT RANGE
PARTICULARLY OVER THE NORTH HALF OF THE LAKE. WINDS DIMINISH
THURSDAY..THEN TURN BACK TO THE SOUTHEAST AND INCREASE AGAIN
THURSDAY NIGHT INTO FRIDAY. BY FRIDAY...SOUTH WINDS TO 30 KT ARE
EXPECTED OVER THE NORTH HALF OF THE LAKE AND A BRIEF PERIOD OF SOUTH
GALES IS NOT OUT OF THE QUESTION. WINDS WILL REMAIN FRESH THROUGH
THE WEEKEND...TURNING NORTHWEST ON SUNDAY AS ANOTHER COLD FRONT
MOVES ACROSS THE LAKE.

BMD

&&

.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 170739
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
239 AM CDT Wed Sep 17 2014

.SHORT TERM...(Today)
ISSUED AT 237 AM CDT WED SEP 17 2014

Recently issued a Dense Fog Advisory across portions of east-central
and southeast Illinois to account for rapidly expanding dense fog.
This dense fog is forming along a northeast-southwest surface ridge
axis, in an area with near zero surface temperature/dew point
spreads and calm winds. It is not entirely clear how far north and
west of the ridge axis a dense fog threat exists, as winds are dead
calm across most of the forecast area. However, a small
temperature/dew point spread exists north/west of the current Dense
Fog Advisory area, and some mid clouds are beginning to spill across
central Illinois from a short wave moving through the plains. These
factors lead me to believe the current advisory should be sufficient.

Aside from the locally dense morning fog, the only forecast problem
for the day revolves around the precipitation threat (if any) from
the wave moving through the Plains. Some of the model guidance is
suggesting the far southern part of the forecast area may be brushed
by light rainfall later today. However, think these precipitation
forecasts are likely too far north. The model consensus has the vort
max with the short wave staying south of the forecast area, along
with the bulk of the isentropic lift ahead of the wave. These
factors, combined with the dry air mass currently in place, support
continuing with our current dry forecast for today. Temperatures
today are likely to be similar to yesterday`s. While weak low
level warm air advection will be taking place, it is likely to be
offset to some degree by additional cloud cover today.


&&

.LONG TERM...(Tonight through Tuesday)
ISSUED AT 237 AM CDT WED SEP 17 2014

High pressure over the Great Lakes to keep us in a dry east to
northeast flow into Thursday evening. After that, incoming shortwave
from the northwest comes into play. As with the daytime models, the
evening runs have continued the trend that the remnant moisture from
Odile will probably make it about as far as Missouri before shunting
southeast, so the incoming wave never really draws from it. This
lessens the threat of widespread heavy rain. The southeast half of
the CWA will likely remain dry through Saturday, while rain chances
increase across the northwest during the afternoon, and the best
chances occur Saturday night.

Sunday may be a bit of a question mark. The GFS and Canadian models
both have a rather clean frontal passage with lingering rain ending
in the morning. However, the latest ECMWF slows the front as a
surface low forms over Kansas, lingering rain across the south half
of the forecast area into Sunday evening. There may be a bit of a
feedback issue with that solution, so will maintain the dry
conditions by Sunday evening.

Rather large surface high will dominate the Midwest early next week,
with dry conditions for a few days.


&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
ISSUED AT 1130 PM CDT TUE SEP 16 2014

Surface high pressure meandering across the Midwest will bring
light and variable winds for the next 24 hours. A weak mid-level
shortwave trough crossing Illinois will cause some cloud cover
overnight, but no MVFR ceilings. Fog mention in TAFs continues to
be MVFR from 09Z-12Z, however areas mainly KTAZ-KPRG southward
could see lower values due to higher dew points and less cloud
cover expected overnight. Visibility locally down to VLIFR
category is possible. For Wednesday afternoon, scattered cloud
cover expected as daytime heating interacts with low level
moisture, but any local ceilings should remain above MVFR
thresholds.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY until 10 AM CDT this morning FOR ILZ054>057-
061>063-066>068-071>073.

&&

$$

SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...ONTON







000
FXUS63 KILX 170739
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
239 AM CDT Wed Sep 17 2014

.SHORT TERM...(Today)
ISSUED AT 237 AM CDT WED SEP 17 2014

Recently issued a Dense Fog Advisory across portions of east-central
and southeast Illinois to account for rapidly expanding dense fog.
This dense fog is forming along a northeast-southwest surface ridge
axis, in an area with near zero surface temperature/dew point
spreads and calm winds. It is not entirely clear how far north and
west of the ridge axis a dense fog threat exists, as winds are dead
calm across most of the forecast area. However, a small
temperature/dew point spread exists north/west of the current Dense
Fog Advisory area, and some mid clouds are beginning to spill across
central Illinois from a short wave moving through the plains. These
factors lead me to believe the current advisory should be sufficient.

Aside from the locally dense morning fog, the only forecast problem
for the day revolves around the precipitation threat (if any) from
the wave moving through the Plains. Some of the model guidance is
suggesting the far southern part of the forecast area may be brushed
by light rainfall later today. However, think these precipitation
forecasts are likely too far north. The model consensus has the vort
max with the short wave staying south of the forecast area, along
with the bulk of the isentropic lift ahead of the wave. These
factors, combined with the dry air mass currently in place, support
continuing with our current dry forecast for today. Temperatures
today are likely to be similar to yesterday`s. While weak low
level warm air advection will be taking place, it is likely to be
offset to some degree by additional cloud cover today.


&&

.LONG TERM...(Tonight through Tuesday)
ISSUED AT 237 AM CDT WED SEP 17 2014

High pressure over the Great Lakes to keep us in a dry east to
northeast flow into Thursday evening. After that, incoming shortwave
from the northwest comes into play. As with the daytime models, the
evening runs have continued the trend that the remnant moisture from
Odile will probably make it about as far as Missouri before shunting
southeast, so the incoming wave never really draws from it. This
lessens the threat of widespread heavy rain. The southeast half of
the CWA will likely remain dry through Saturday, while rain chances
increase across the northwest during the afternoon, and the best
chances occur Saturday night.

Sunday may be a bit of a question mark. The GFS and Canadian models
both have a rather clean frontal passage with lingering rain ending
in the morning. However, the latest ECMWF slows the front as a
surface low forms over Kansas, lingering rain across the south half
of the forecast area into Sunday evening. There may be a bit of a
feedback issue with that solution, so will maintain the dry
conditions by Sunday evening.

Rather large surface high will dominate the Midwest early next week,
with dry conditions for a few days.


&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
ISSUED AT 1130 PM CDT TUE SEP 16 2014

Surface high pressure meandering across the Midwest will bring
light and variable winds for the next 24 hours. A weak mid-level
shortwave trough crossing Illinois will cause some cloud cover
overnight, but no MVFR ceilings. Fog mention in TAFs continues to
be MVFR from 09Z-12Z, however areas mainly KTAZ-KPRG southward
could see lower values due to higher dew points and less cloud
cover expected overnight. Visibility locally down to VLIFR
category is possible. For Wednesday afternoon, scattered cloud
cover expected as daytime heating interacts with low level
moisture, but any local ceilings should remain above MVFR
thresholds.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY until 10 AM CDT this morning FOR ILZ054>057-
061>063-066>068-071>073.

&&

$$

SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...ONTON






000
FXUS63 KLOT 170731
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
231 AM CDT WED SEP 17 2014

.DISCUSSION...
231 AM CDT

OVERARCHING THEME OF THE FORECAST FOR THE NEXT SEVEN DAYS IS FAIRLY
NICE EARLY FALL WEATHER WITH A DASH OF UNSEASONABLE WARMTH AND
SPLASH OF THUNDERSTORMS.

TODAY LOOKS TO BE ANOTHER GLORIOUS DAY...LIKELY A COUPLE/FEW DEGREES
WARMER THAN TUESDAY. GUIDANCE WAS A COUPLE DEGREES TOO COOL WITH
HIGHS TUESDAY AND WITH 925MB AND 850MB TEMPS PROGGED TO BE 2-3C
WARMER THAN YESTERDAY HAVE OPTED TO GO A COUPLE DEGREES ABOVE
GUIDANCE WITH HIGHS NEAR OR INTO THE LOWER 70S MOST AREAS. SOME
ACCAS AND MID LEVEL CLOUDINESS UPSTREAM ASSOCIATED WITH MID-LEVEL
WARM AIR ADVECTION COULD LEAD TO A BIT MORE CLOUDINESS THAN THE
NEARLY CLOUD FREE SKIES TUESDAY BUT STILL LOOK FOR PLENTY OF
SUNSHINE TODAY.

WEAKENING BACKDOOR COLD FRONT MOVES IN OFF THE LAKE EARLY THURSDAY
MORNING RESULTING IN SOME SLIGHTLY COOLER TEMPS THURS...ESPECIALLY
DOWNWIND OF THE LAKE WHERE NORTHEAST WINDS WILL HAVE A BETTER UMPH
BEHIND THE FRONT AND RESULT IN A GREATER LAKE INFLUENCE TO TEMPS.
WINDS BEGIN TO VEER AND SHOULD BECOMING SOUTHEASTERLY THURSDAY NIGHT
WITH WARM AIR ADVECTION GETTING UNDERWAY. WARM AIR ADVECTION GETS
GOING INTO FULL GEAR BY LATE FRIDAY AND GIVEN THE LATER ARRIVAL OF
THE TOASTIER TEMPS ITS UNCLEAR HOW MUCH WARMING WILL BE REALIZED
WITH HIGHS FRIDAY. HAVE CONSERVATIVELY BUMPED TEMPS UP INTO THE 70S
AREA WIDE...BUT PROGGED 00Z 850MB/925MB TEMPS WOULD ACTUALLY SUPPORT
TEMPS AROUND 80F. FRIDAY NIGHT LOOKS TO BE FAIRLY WARM WITH
SOUTHERLY WINDS CONTINUING...IN FACT MANY AREAS WILL SEE LOW TEMPS
FRI NIGHT WARMER THAN HIGH TEMPS WERE LAST WEEK! GUIDANCE CONTINUES
TO ADVERTISE 850MB TEMPS IN THE MID-UPPER TEENS WITH 925MB TEMPS
AROUND 20C...WHICH CLIMO SUGGESTS HIGHS WELL INTO THE 80S. HAVE
TRENDED TEMPS UPWARD SOME INTO THE LOW TO MID 80S AND WITH ENOUGH
SUNSHINE EVEN THOSE FORECAST HIGHS COULD END UP BEING A BIT TOO LOW!

COLD FRONT STILL LOOKS SLATED TO ARRIVE LATE SATURDAY WITH SHOWERS
AND THUNDERSTORMS CERTAINLY LOOKING LIKE A DECENT BET ALONG THE
FRONT. MEDIUM RANGE GUIDANCE HAS TRENDED TOWARD LESS PHASING WITH
THE NORTHERN STREAM TROUGH AND THE REMNANTS OF ODILE...SO NOT
LOOKING LIKE QUITE AS BIG OF A RAIN PRODUCER AS PREVIOUS RUNS
SUGGESTED. THE PUSH OF COLDER AIR BEHIND THE FRONT SATURDAY LOOKS TO
COME IN PHASES...WITH THE FIRST PHASE INITIALLY LOOKING LIKE MORE OF
A PUSH OF PACIFIC AIR SUNDAY BEFORE SECONDARY PUSH OF MORE
SUBSTANTIAL COLD AIR ARRIVES EARLY NEXT WEEK SENDING TEMPS DROPPING
BELOW AVERAGE AGAIN.

IZZI

&&

.AVIATION...

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

* LAKE BREEZE WEDNESDAY AFTERNOON.

BMD

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

ANOTHER QUIET WEATHER DAY IS ON TAP FOR THE REGION WITH HIGH
PRESSURE CENTERED SOUTH OF THE AREA PROVIDING CONTINUED LIGHT FLOW
AND PRIMARILY VFR CONDITIONS OUTSIDE OF SOME PATCHY FOG. FOG IS
EXPECTED TO STAY SOUTH OF THE TERMINALS TONIGHT. A FEW MID LEVEL
CLOUDS MAY DEVELOP MIDDAY WEDNESDAY. A LAKE BREEZE IS ALSO EXPECTED
TO DEVELOP AND SHOULD PUSH ACROSS THE TERMINALS EARLY TO MID
AFTERNOON TURNING WINDS EASTERLY AND BRIEFLY INCREASING SPEEDS INTO
THE 7-9 KT RANGE.

BMD

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

* MEDIUM-HIGH ON LAKE BREEZE TO WITHIN A COUPLE HOURS.
* HIGH ON REMAINING FORECAST ELEMENTS.

BMD

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

* THURSDAY AND FRIDAY...DRY/VFR.
* SATURDAY...CHANCE TSRA. GUSTY SOUTHWEST WINDS.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY...DRY/VFR.

&&

.MARINE...
222 AM CDT

AREAS OF HIGH PRESSURE LIE ACROSS THE OHIO VALLEY AND THE CANADIAN
PRAIRIES EARLY THIS MORNING WITH COLD FRONT IN BETWEEN THESE TWO
FEATURES JUST NORTH OF LAKE MICHIGAN. THIS FRONT WILL MOVE SOUTH
ACROSS THE LAKE THIS EVENING AND TONIGHT WITH WINDS TURNING
NORTHEAST AND INCREASING SHARPLY INTO THE 20-25 KT RANGE
PARTICULARLY OVER THE NORTH HALF OF THE LAKE. WINDS DIMINISH
THURSDAY..THEN TURN BACK TO THE SOUTHEAST AND INCREASE AGAIN
THURSDAY NIGHT INTO FRIDAY. BY FRIDAY...SOUTH WINDS TO 30 KT ARE
EXPECTED OVER THE NORTH HALF OF THE LAKE AND A BRIEF PERIOD OF SOUTH
GALES IS NOT OUT OF THE QUESTION. WINDS WILL REMAIN FRESH THROUGH
THE WEEKEND...TURNING NORTHWEST ON SUNDAY AS ANOTHER COLD FRONT
MOVES ACROSS THE LAKE.

BMD

&&

.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 170731
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
231 AM CDT WED SEP 17 2014

.DISCUSSION...
231 AM CDT

OVERARCHING THEME OF THE FORECAST FOR THE NEXT SEVEN DAYS IS FAIRLY
NICE EARLY FALL WEATHER WITH A DASH OF UNSEASONABLE WARMTH AND
SPLASH OF THUNDERSTORMS.

TODAY LOOKS TO BE ANOTHER GLORIOUS DAY...LIKELY A COUPLE/FEW DEGREES
WARMER THAN TUESDAY. GUIDANCE WAS A COUPLE DEGREES TOO COOL WITH
HIGHS TUESDAY AND WITH 925MB AND 850MB TEMPS PROGGED TO BE 2-3C
WARMER THAN YESTERDAY HAVE OPTED TO GO A COUPLE DEGREES ABOVE
GUIDANCE WITH HIGHS NEAR OR INTO THE LOWER 70S MOST AREAS. SOME
ACCAS AND MID LEVEL CLOUDINESS UPSTREAM ASSOCIATED WITH MID-LEVEL
WARM AIR ADVECTION COULD LEAD TO A BIT MORE CLOUDINESS THAN THE
NEARLY CLOUD FREE SKIES TUESDAY BUT STILL LOOK FOR PLENTY OF
SUNSHINE TODAY.

WEAKENING BACKDOOR COLD FRONT MOVES IN OFF THE LAKE EARLY THURSDAY
MORNING RESULTING IN SOME SLIGHTLY COOLER TEMPS THURS...ESPECIALLY
DOWNWIND OF THE LAKE WHERE NORTHEAST WINDS WILL HAVE A BETTER UMPH
BEHIND THE FRONT AND RESULT IN A GREATER LAKE INFLUENCE TO TEMPS.
WINDS BEGIN TO VEER AND SHOULD BECOMING SOUTHEASTERLY THURSDAY NIGHT
WITH WARM AIR ADVECTION GETTING UNDERWAY. WARM AIR ADVECTION GETS
GOING INTO FULL GEAR BY LATE FRIDAY AND GIVEN THE LATER ARRIVAL OF
THE TOASTIER TEMPS ITS UNCLEAR HOW MUCH WARMING WILL BE REALIZED
WITH HIGHS FRIDAY. HAVE CONSERVATIVELY BUMPED TEMPS UP INTO THE 70S
AREA WIDE...BUT PROGGED 00Z 850MB/925MB TEMPS WOULD ACTUALLY SUPPORT
TEMPS AROUND 80F. FRIDAY NIGHT LOOKS TO BE FAIRLY WARM WITH
SOUTHERLY WINDS CONTINUING...IN FACT MANY AREAS WILL SEE LOW TEMPS
FRI NIGHT WARMER THAN HIGH TEMPS WERE LAST WEEK! GUIDANCE CONTINUES
TO ADVERTISE 850MB TEMPS IN THE MID-UPPER TEENS WITH 925MB TEMPS
AROUND 20C...WHICH CLIMO SUGGESTS HIGHS WELL INTO THE 80S. HAVE
TRENDED TEMPS UPWARD SOME INTO THE LOW TO MID 80S AND WITH ENOUGH
SUNSHINE EVEN THOSE FORECAST HIGHS COULD END UP BEING A BIT TOO LOW!

COLD FRONT STILL LOOKS SLATED TO ARRIVE LATE SATURDAY WITH SHOWERS
AND THUNDERSTORMS CERTAINLY LOOKING LIKE A DECENT BET ALONG THE
FRONT. MEDIUM RANGE GUIDANCE HAS TRENDED TOWARD LESS PHASING WITH
THE NORTHERN STREAM TROUGH AND THE REMNANTS OF ODILE...SO NOT
LOOKING LIKE QUITE AS BIG OF A RAIN PRODUCER AS PREVIOUS RUNS
SUGGESTED. THE PUSH OF COLDER AIR BEHIND THE FRONT SATURDAY LOOKS TO
COME IN PHASES...WITH THE FIRST PHASE INITIALLY LOOKING LIKE MORE OF
A PUSH OF PACIFIC AIR SUNDAY BEFORE SECONDARY PUSH OF MORE
SUBSTANTIAL COLD AIR ARRIVES EARLY NEXT WEEK SENDING TEMPS DROPPING
BELOW AVERAGE AGAIN.

IZZI

&&

.AVIATION...

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

* LAKE BREEZE WEDNESDAY AFTERNOON.

BMD

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

ANOTHER QUIET WEATHER DAY IS ON TAP FOR THE REGION WITH HIGH
PRESSURE CENTERED SOUTH OF THE AREA PROVIDING CONTINUED LIGHT FLOW
AND PRIMARILY VFR CONDITIONS OUTSIDE OF SOME PATCHY FOG. FOG IS
EXPECTED TO STAY SOUTH OF THE TERMINALS TONIGHT. A FEW MID LEVEL
CLOUDS MAY DEVELOP MIDDAY WEDNESDAY. A LAKE BREEZE IS ALSO EXPECTED
TO DEVELOP AND SHOULD PUSH ACROSS THE TERMINALS EARLY TO MID
AFTERNOON TURNING WINDS EASTERLY AND BRIEFLY INCREASING SPEEDS INTO
THE 7-9 KT RANGE.

BMD

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

* MEDIUM-HIGH ON LAKE BREEZE TO WITHIN A COUPLE HOURS.
* HIGH ON REMAINING FORECAST ELEMENTS.

BMD

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

* THURSDAY AND FRIDAY...DRY/VFR.
* SATURDAY...CHANCE TSRA. GUSTY SOUTHWEST WINDS.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY...DRY/VFR.

&&

.MARINE...
222 AM CDT

AREAS OF HIGH PRESSURE LIE ACROSS THE OHIO VALLEY AND THE CANADIAN
PRAIRIES EARLY THIS MORNING WITH COLD FRONT IN BETWEEN THESE TWO
FEATURES JUST NORTH OF LAKE MICHIGAN. THIS FRONT WILL MOVE SOUTH
ACROSS THE LAKE THIS EVENING AND TONIGHT WITH WINDS TURNING
NORTHEAST AND INCREASING SHARPLY INTO THE 20-25 KT RANGE
PARTICULARLY OVER THE NORTH HALF OF THE LAKE. WINDS DIMINISH
THURSDAY..THEN TURN BACK TO THE SOUTHEAST AND INCREASE AGAIN
THURSDAY NIGHT INTO FRIDAY. BY FRIDAY...SOUTH WINDS TO 30 KT ARE
EXPECTED OVER THE NORTH HALF OF THE LAKE AND A BRIEF PERIOD OF SOUTH
GALES IS NOT OUT OF THE QUESTION. WINDS WILL REMAIN FRESH THROUGH
THE WEEKEND...TURNING NORTHWEST ON SUNDAY AS ANOTHER COLD FRONT
MOVES ACROSS THE LAKE.

BMD

&&

.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 170723
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
223 AM CDT WED SEP 17 2014

.DISCUSSION...
908 PM CDT

ONLY MINOR CHANGES MADE TO THE REST OF TONIGHTS FORECAST. WITH
CLEAR SKIES AND LIGHT WINDS ALLOWING FOR IDEAL RADIATIONAL COOLING
IN THE CONTINUED COOL AND DRY AIR MASS...TEMPERATURES DROPPED AS
MUCH AS 15 DEGREES IN TWO HOURS EARLY THIS EVENING. CONSIDERING
MINIMUM TEMPERATURES LAST NIGHT AND DEW POINTS RUNNING LOWER AT
MOST LOCATIONS...HAVE NUDGED MINIMUM TEMPERATURES DOWN A COUPLE
DEGREES. WOULD EXPECT TO SEE SOME ISOLATED SUB 40 DEGREE READINGS
IN THE USUAL OUTLYING LOCATIONS.

SLIGHTLY HIGHER BOUNDARY LAYER MOISTURE EXISTS IN PARTS OF EAST
CENTRAL IL AND NORTHWEST IN...AS EVIDENCED BY DEW POINTS AND
EARLIER DAYTIME CUMULUS. THIS PROBABLY WILL ALLOW FOR PATCHY
SHALLOW FOG IN THIS AREA. HAVE ADDED INTO THE FORECAST BUT SHOULD
NOT BE A BIG IMPACT.

MTF

//PREV DISCUSSION...
254 PM CDT

TONIGHT...
HIGH PRESSURE HAS BECOME CENTERED OVER THE REGION TODAY...PROVIDING
ABUNDANT SUNSHINE AND LIGHT WINDS. THIS EVENING IS SETTING UP TO BE
A BEAUTIFUL ONE WITH MOSTLY CLEAR SKIES AND NEARLY CALM WINDS FOR
MUCH OF THE OVERNIGHT HOURS. TEMPS WILL RADIATE ONCE AGAIN INTO THE
LOW 40S FOR MUCH OF THE FORECAST AREA...WITH THE EXCEPTION BEING
DOWNTOWN CHICAGO WHERE TEMPS WILL LIKELY HOLD IN THE UPR 40S/ARND
50.

WEDNESDAY THROUGH FRIDAY...
MID-LVL TROUGH WILL REMAIN OVERHEAD THRU WED WITH A CONTINUED LIGHT
NORTHWEST FLOW. AT THE SFC BROAD SFC RIDGING WILL REMAIN IN
PLACE...WITH ABUNDANT SUNSHINE ONCE AGAIN WED AFTN. A BACKDOOR FRONT
WILL SLIP SOUTH ACROSS THE LAKE/NORTHERN GREAT LAKES WED EARLY
MORNING...EVENTUALLY ARRIVING ACROSS NORTHERN IL/NORTHWEST IN LATE
WED NGT/EARLY THUR MORNING. THIS WILL LIKELY PRODUCE AN AREA OF
STRATUS AS IT ARRIVES...HOWEVER AT THIS TIME DRY CONDS ARE EXPECTED
TO PERSIST THRU THUR. THEN ANOTHER SFC RIDGE IS POISED TO SLIDE
SOUTH FROM CENTRAL CANADA...AND LINGER OVER THE REGION THRU EARLY
FRI.

AS THE SFC RIDGE FRI BEGINS TO DRIFT EAST...THE MID-LVL FLOW WILL
BEGIN TO FLATTEN. THIS WILL ALLOW A STEADY TURNING IN THE LLVL FLOW
TO THE SOUTH/SOUTHWEST AND BEGIN ADVECTING WARMER/MOIST AIR INTO THE
REGION FRI NGT. GUIDANCE HAS BEEN STEADILY PUSHING POPS BACK UNTIL
FRI NGT...AND COULD SEE THE SFC RIDGE HOLDING INTO FRI NGT WITH POPS
HOLDING OFF UNTIL EARLY SAT.

TEMPS WED/THUR WILL GENERALLY BE IN THE MID/UPR 60S...WITH A FEW
POINTS POSSIBLY TOUCHING 70 MAINLY SOUTH OF I-80. WITH THE BACKDOOR
FRONT SLIPPING SOUTH IT IS POSSIBLE THE CLOUDS COULD LINGER LONG
ENOUGH THUR THAT TEMPS HOLD IN THE LOW 60S TO POSSIBLY UPR 50S
ACROSS THE NORTHERN IL SECTIONS. THEN FOR FRI TEMPS WILL LIKELY
BEGIN TO CLIMB INTO THE LOW TO POSSIBLY MID 70S. OVERNIGHT LOWS WILL
GENERALLY BE IN THE 40S TO LOW 50S.

CONFIDENCE...HIGH.

SATURDAY THROUGH MONDAY...
ENSEMBLES HAVE COME INTO SLIGHTLY BETTER AGREEMENT IN THE SAT/SUN
TIMEFRAME WITH THE 500MB FLOW REMAINING SOMEWHAT FLAT...WHICH SHOULD
HELP TO BRING THE EXPECTED CHANNEL OF MOISTURE/CONVECTION INTO THE
REGION BUT REMAIN PROGRESSIVE. THEN FOR THE SECOND HALF OF THE
WEEKEND ENSEMBLES RETURN THE MID-LVL RIDGE TO THE WESTERN
CONUS...WITH DOWNSTREAM TROUGHING DEVELOPING OVER THE GREAT LAKES
REGION EARLY NEXT WEEK. IT APPEARS THE BEST DAY FOR CONVECTION WILL
END UP BEING SAT NGT/SUN MORNING. TEMPS WILL LIKELY APPROACH 80 DEG
SAT...AND PERHAPS EVEN THE LOW 80S ACROSS THE SOUTHERN CWFA. HOWEVER
THIS WARM-UP APPEARS TO ONLY BE BRIEF WITH TEMPS SUN BACK INTO THE
LOW 70S AND 60S FOR MON.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* LAKE BREEZE WEDNESDAY AFTERNOON.

BMD

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

ANOTHER QUIET WEATHER DAY IS ON TAP FOR THE REGION WITH HIGH
PRESSURE CENTERED SOUTH OF THE AREA PROVIDING CONTINUED LIGHT FLOW
AND PRIMARILY VFR CONDITIONS OUTSIDE OF SOME PATCHY FOG. FOG IS
EXPECTED TO STAY SOUTH OF THE TERMINALS TONIGHT. A FEW MID LEVEL
CLOUDS MAY DEVELOP MIDDAY WEDNESDAY. A LAKE BREEZE IS ALSO EXPECTED
TO DEVELOP AND SHOULD PUSH ACROSS THE TERMINALS EARLY TO MID
AFTERNOON TURNING WINDS EASTERLY AND BRIEFLY INCREASING SPEEDS INTO
THE 7-9 KT RANGE.

BMD

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

* MEDIUM-HIGH ON LAKE BREEZE TO WITHIN A COUPLE HOURS.
* HIGH ON REMAINING FORECAST ELEMENTS.

BMD

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

* THURSDAY AND FRIDAY...DRY/VFR.
* SATURDAY...CHANCE TSRA. GUSTY SOUTHWEST WINDS.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY...DRY/VFR.

&&

.MARINE...
222 AM CDT

AREAS OF HIGH PRESSURE LIE ACROSS THE OHIO VALLEY AND THE CANADIAN
PRAIRIES EARLY THIS MORNING WITH COLD FRONT IN BETWEEN THESE TWO
FEATURES JUST NORTH OF LAKE MICHIGAN. THIS FRONT WILL MOVE SOUTH
ACROSS THE LAKE THIS EVENING AND TONIGHT WITH WINDS TURNING
NORTHEAST AND INCREASING SHARPLY INTO THE 20-25 KT RANGE
PARTICULARLY OVER THE NORTH HALF OF THE LAKE. WINDS DIMINISH
THURSDAY..THEN TURN BACK TO THE SOUTHEAST AND INCREASE AGAIN
THURSDAY NIGHT INTO FRIDAY. BY FRIDAY...SOUTH WINDS TO 30 KT ARE
EXPECTED OVER THE NORTH HALF OF THE LAKE AND A BRIEF PERIOD OF SOUTH
GALES IS NOT OUT OF THE QUESTION. WINDS WILL REMAIN FRESH THROUGH
THE WEEKEND...TURNING NORTHWEST ON SUNDAY AS ANOTHER COLD FRONT
MOVES ACROSS THE LAKE.

BMD

&&

.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 170723
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
223 AM CDT WED SEP 17 2014

.DISCUSSION...
908 PM CDT

ONLY MINOR CHANGES MADE TO THE REST OF TONIGHTS FORECAST. WITH
CLEAR SKIES AND LIGHT WINDS ALLOWING FOR IDEAL RADIATIONAL COOLING
IN THE CONTINUED COOL AND DRY AIR MASS...TEMPERATURES DROPPED AS
MUCH AS 15 DEGREES IN TWO HOURS EARLY THIS EVENING. CONSIDERING
MINIMUM TEMPERATURES LAST NIGHT AND DEW POINTS RUNNING LOWER AT
MOST LOCATIONS...HAVE NUDGED MINIMUM TEMPERATURES DOWN A COUPLE
DEGREES. WOULD EXPECT TO SEE SOME ISOLATED SUB 40 DEGREE READINGS
IN THE USUAL OUTLYING LOCATIONS.

SLIGHTLY HIGHER BOUNDARY LAYER MOISTURE EXISTS IN PARTS OF EAST
CENTRAL IL AND NORTHWEST IN...AS EVIDENCED BY DEW POINTS AND
EARLIER DAYTIME CUMULUS. THIS PROBABLY WILL ALLOW FOR PATCHY
SHALLOW FOG IN THIS AREA. HAVE ADDED INTO THE FORECAST BUT SHOULD
NOT BE A BIG IMPACT.

MTF

//PREV DISCUSSION...
254 PM CDT

TONIGHT...
HIGH PRESSURE HAS BECOME CENTERED OVER THE REGION TODAY...PROVIDING
ABUNDANT SUNSHINE AND LIGHT WINDS. THIS EVENING IS SETTING UP TO BE
A BEAUTIFUL ONE WITH MOSTLY CLEAR SKIES AND NEARLY CALM WINDS FOR
MUCH OF THE OVERNIGHT HOURS. TEMPS WILL RADIATE ONCE AGAIN INTO THE
LOW 40S FOR MUCH OF THE FORECAST AREA...WITH THE EXCEPTION BEING
DOWNTOWN CHICAGO WHERE TEMPS WILL LIKELY HOLD IN THE UPR 40S/ARND
50.

WEDNESDAY THROUGH FRIDAY...
MID-LVL TROUGH WILL REMAIN OVERHEAD THRU WED WITH A CONTINUED LIGHT
NORTHWEST FLOW. AT THE SFC BROAD SFC RIDGING WILL REMAIN IN
PLACE...WITH ABUNDANT SUNSHINE ONCE AGAIN WED AFTN. A BACKDOOR FRONT
WILL SLIP SOUTH ACROSS THE LAKE/NORTHERN GREAT LAKES WED EARLY
MORNING...EVENTUALLY ARRIVING ACROSS NORTHERN IL/NORTHWEST IN LATE
WED NGT/EARLY THUR MORNING. THIS WILL LIKELY PRODUCE AN AREA OF
STRATUS AS IT ARRIVES...HOWEVER AT THIS TIME DRY CONDS ARE EXPECTED
TO PERSIST THRU THUR. THEN ANOTHER SFC RIDGE IS POISED TO SLIDE
SOUTH FROM CENTRAL CANADA...AND LINGER OVER THE REGION THRU EARLY
FRI.

AS THE SFC RIDGE FRI BEGINS TO DRIFT EAST...THE MID-LVL FLOW WILL
BEGIN TO FLATTEN. THIS WILL ALLOW A STEADY TURNING IN THE LLVL FLOW
TO THE SOUTH/SOUTHWEST AND BEGIN ADVECTING WARMER/MOIST AIR INTO THE
REGION FRI NGT. GUIDANCE HAS BEEN STEADILY PUSHING POPS BACK UNTIL
FRI NGT...AND COULD SEE THE SFC RIDGE HOLDING INTO FRI NGT WITH POPS
HOLDING OFF UNTIL EARLY SAT.

TEMPS WED/THUR WILL GENERALLY BE IN THE MID/UPR 60S...WITH A FEW
POINTS POSSIBLY TOUCHING 70 MAINLY SOUTH OF I-80. WITH THE BACKDOOR
FRONT SLIPPING SOUTH IT IS POSSIBLE THE CLOUDS COULD LINGER LONG
ENOUGH THUR THAT TEMPS HOLD IN THE LOW 60S TO POSSIBLY UPR 50S
ACROSS THE NORTHERN IL SECTIONS. THEN FOR FRI TEMPS WILL LIKELY
BEGIN TO CLIMB INTO THE LOW TO POSSIBLY MID 70S. OVERNIGHT LOWS WILL
GENERALLY BE IN THE 40S TO LOW 50S.

CONFIDENCE...HIGH.

SATURDAY THROUGH MONDAY...
ENSEMBLES HAVE COME INTO SLIGHTLY BETTER AGREEMENT IN THE SAT/SUN
TIMEFRAME WITH THE 500MB FLOW REMAINING SOMEWHAT FLAT...WHICH SHOULD
HELP TO BRING THE EXPECTED CHANNEL OF MOISTURE/CONVECTION INTO THE
REGION BUT REMAIN PROGRESSIVE. THEN FOR THE SECOND HALF OF THE
WEEKEND ENSEMBLES RETURN THE MID-LVL RIDGE TO THE WESTERN
CONUS...WITH DOWNSTREAM TROUGHING DEVELOPING OVER THE GREAT LAKES
REGION EARLY NEXT WEEK. IT APPEARS THE BEST DAY FOR CONVECTION WILL
END UP BEING SAT NGT/SUN MORNING. TEMPS WILL LIKELY APPROACH 80 DEG
SAT...AND PERHAPS EVEN THE LOW 80S ACROSS THE SOUTHERN CWFA. HOWEVER
THIS WARM-UP APPEARS TO ONLY BE BRIEF WITH TEMPS SUN BACK INTO THE
LOW 70S AND 60S FOR MON.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* LAKE BREEZE WEDNESDAY AFTERNOON.

BMD

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

ANOTHER QUIET WEATHER DAY IS ON TAP FOR THE REGION WITH HIGH
PRESSURE CENTERED SOUTH OF THE AREA PROVIDING CONTINUED LIGHT FLOW
AND PRIMARILY VFR CONDITIONS OUTSIDE OF SOME PATCHY FOG. FOG IS
EXPECTED TO STAY SOUTH OF THE TERMINALS TONIGHT. A FEW MID LEVEL
CLOUDS MAY DEVELOP MIDDAY WEDNESDAY. A LAKE BREEZE IS ALSO EXPECTED
TO DEVELOP AND SHOULD PUSH ACROSS THE TERMINALS EARLY TO MID
AFTERNOON TURNING WINDS EASTERLY AND BRIEFLY INCREASING SPEEDS INTO
THE 7-9 KT RANGE.

BMD

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

* MEDIUM-HIGH ON LAKE BREEZE TO WITHIN A COUPLE HOURS.
* HIGH ON REMAINING FORECAST ELEMENTS.

BMD

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

* THURSDAY AND FRIDAY...DRY/VFR.
* SATURDAY...CHANCE TSRA. GUSTY SOUTHWEST WINDS.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY...DRY/VFR.

&&

.MARINE...
222 AM CDT

AREAS OF HIGH PRESSURE LIE ACROSS THE OHIO VALLEY AND THE CANADIAN
PRAIRIES EARLY THIS MORNING WITH COLD FRONT IN BETWEEN THESE TWO
FEATURES JUST NORTH OF LAKE MICHIGAN. THIS FRONT WILL MOVE SOUTH
ACROSS THE LAKE THIS EVENING AND TONIGHT WITH WINDS TURNING
NORTHEAST AND INCREASING SHARPLY INTO THE 20-25 KT RANGE
PARTICULARLY OVER THE NORTH HALF OF THE LAKE. WINDS DIMINISH
THURSDAY..THEN TURN BACK TO THE SOUTHEAST AND INCREASE AGAIN
THURSDAY NIGHT INTO FRIDAY. BY FRIDAY...SOUTH WINDS TO 30 KT ARE
EXPECTED OVER THE NORTH HALF OF THE LAKE AND A BRIEF PERIOD OF SOUTH
GALES IS NOT OUT OF THE QUESTION. WINDS WILL REMAIN FRESH THROUGH
THE WEEKEND...TURNING NORTHWEST ON SUNDAY AS ANOTHER COLD FRONT
MOVES ACROSS THE LAKE.

BMD

&&

.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 170522
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1222 AM CDT WED SEP 17 2014

.DISCUSSION...
908 PM CDT

ONLY MINOR CHANGES MADE TO THE REST OF TONIGHTS FORECAST. WITH
CLEAR SKIES AND LIGHT WINDS ALLOWING FOR IDEAL RADIATIONAL COOLING
IN THE CONTINUED COOL AND DRY AIR MASS...TEMPERATURES DROPPED AS
MUCH AS 15 DEGREES IN TWO HOURS EARLY THIS EVENING. CONSIDERING
MINIMUM TEMPERATURES LAST NIGHT AND DEW POINTS RUNNING LOWER AT
MOST LOCATIONS...HAVE NUDGED MINIMUM TEMPERATURES DOWN A COUPLE
DEGREES. WOULD EXPECT TO SEE SOME ISOLATED SUB 40 DEGREE READINGS
IN THE USUAL OUTLYING LOCATIONS.

SLIGHTLY HIGHER BOUNDARY LAYER MOISTURE EXISTS IN PARTS OF EAST
CENTRAL IL AND NORTHWEST IN...AS EVIDENCED BY DEW POINTS AND
EARLIER DAYTIME CUMULUS. THIS PROBABLY WILL ALLOW FOR PATCHY
SHALLOW FOG IN THIS AREA. HAVE ADDED INTO THE FORECAST BUT SHOULD
NOT BE A BIG IMPACT.

MTF

//PREV DISCUSSION...
254 PM CDT

TONIGHT...
HIGH PRESSURE HAS BECOME CENTERED OVER THE REGION TODAY...PROVIDING
ABUNDANT SUNSHINE AND LIGHT WINDS. THIS EVENING IS SETTING UP TO BE
A BEAUTIFUL ONE WITH MOSTLY CLEAR SKIES AND NEARLY CALM WINDS FOR
MUCH OF THE OVERNIGHT HOURS. TEMPS WILL RADIATE ONCE AGAIN INTO THE
LOW 40S FOR MUCH OF THE FORECAST AREA...WITH THE EXCEPTION BEING
DOWNTOWN CHICAGO WHERE TEMPS WILL LIKELY HOLD IN THE UPR 40S/ARND
50.

WEDNESDAY THROUGH FRIDAY...
MID-LVL TROUGH WILL REMAIN OVERHEAD THRU WED WITH A CONTINUED LIGHT
NORTHWEST FLOW. AT THE SFC BROAD SFC RIDGING WILL REMAIN IN
PLACE...WITH ABUNDANT SUNSHINE ONCE AGAIN WED AFTN. A BACKDOOR FRONT
WILL SLIP SOUTH ACROSS THE LAKE/NORTHERN GREAT LAKES WED EARLY
MORNING...EVENTUALLY ARRIVING ACROSS NORTHERN IL/NORTHWEST IN LATE
WED NGT/EARLY THUR MORNING. THIS WILL LIKELY PRODUCE AN AREA OF
STRATUS AS IT ARRIVES...HOWEVER AT THIS TIME DRY CONDS ARE EXPECTED
TO PERSIST THRU THUR. THEN ANOTHER SFC RIDGE IS POISED TO SLIDE
SOUTH FROM CENTRAL CANADA...AND LINGER OVER THE REGION THRU EARLY
FRI.

AS THE SFC RIDGE FRI BEGINS TO DRIFT EAST...THE MID-LVL FLOW WILL
BEGIN TO FLATTEN. THIS WILL ALLOW A STEADY TURNING IN THE LLVL FLOW
TO THE SOUTH/SOUTHWEST AND BEGIN ADVECTING WARMER/MOIST AIR INTO THE
REGION FRI NGT. GUIDANCE HAS BEEN STEADILY PUSHING POPS BACK UNTIL
FRI NGT...AND COULD SEE THE SFC RIDGE HOLDING INTO FRI NGT WITH POPS
HOLDING OFF UNTIL EARLY SAT.

TEMPS WED/THUR WILL GENERALLY BE IN THE MID/UPR 60S...WITH A FEW
POINTS POSSIBLY TOUCHING 70 MAINLY SOUTH OF I-80. WITH THE BACKDOOR
FRONT SLIPPING SOUTH IT IS POSSIBLE THE CLOUDS COULD LINGER LONG
ENOUGH THUR THAT TEMPS HOLD IN THE LOW 60S TO POSSIBLY UPR 50S
ACROSS THE NORTHERN IL SECTIONS. THEN FOR FRI TEMPS WILL LIKELY
BEGIN TO CLIMB INTO THE LOW TO POSSIBLY MID 70S. OVERNIGHT LOWS WILL
GENERALLY BE IN THE 40S TO LOW 50S.

CONFIDENCE...HIGH.

SATURDAY THROUGH MONDAY...
ENSEMBLES HAVE COME INTO SLIGHTLY BETTER AGREEMENT IN THE SAT/SUN
TIMEFRAME WITH THE 500MB FLOW REMAINING SOMEWHAT FLAT...WHICH SHOULD
HELP TO BRING THE EXPECTED CHANNEL OF MOISTURE/CONVECTION INTO THE
REGION BUT REMAIN PROGRESSIVE. THEN FOR THE SECOND HALF OF THE
WEEKEND ENSEMBLES RETURN THE MID-LVL RIDGE TO THE WESTERN
CONUS...WITH DOWNSTREAM TROUGHING DEVELOPING OVER THE GREAT LAKES
REGION EARLY NEXT WEEK. IT APPEARS THE BEST DAY FOR CONVECTION WILL
END UP BEING SAT NGT/SUN MORNING. TEMPS WILL LIKELY APPROACH 80 DEG
SAT...AND PERHAPS EVEN THE LOW 80S ACROSS THE SOUTHERN CWFA. HOWEVER
THIS WARM-UP APPEARS TO ONLY BE BRIEF WITH TEMPS SUN BACK INTO THE
LOW 70S AND 60S FOR MON.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* LAKE BREEZE WEDNESDAY AFTERNOON.

BMD

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

ANOTHER QUIET WEATHER DAY IS ON TAP FOR THE REGION WITH HIGH
PRESSURE CENTERED SOUTH OF THE AREA PROVIDING CONTINUED LIGHT FLOW
AND PRIMARILY VFR CONDITIONS OUTSIDE OF SOME PATCHY FOG. FOG IS
EXPECTED TO STAY SOUTH OF THE TERMINALS TONIGHT. A FEW MID LEVEL
CLOUDS MAY DEVELOP MIDDAY WEDNESDAY. A LAKE BREEZE IS ALSO EXPECTED
TO DEVELOP AND SHOULD PUSH ACROSS THE TERMINALS EARLY TO MID
AFTERNOON TURNING WINDS EASTERLY AND BRIEFLY INCREASING SPEEDS INTO
THE 7-9 KT RANGE.

BMD


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

* MEDIUM-HIGH ON LAKE BREEZE TO WITHIN A COUPLE HOURS.
* HIGH ON REMAINING FORECAST ELEMENTS.

BMD

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

* THURSDAY AND FRIDAY...DRY/VFR.
* SATURDAY...CHANCE TSRA. GUSTY SOUTHWEST WINDS.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY...DRY/VFR.

&&

.MARINE...
228 PM CDT

HIGH PRESSURE HAS BUILT ACROSS SOUTHERN LAKE MICHIGAN THIS
AFTERNOON. HOWEVER THE SOUTH TO SOUTHWEST GRADIENT HAS INCREASED
ACROSS THE NORTHERN HALF OF THE LAKE AHEAD OF THE NEXT COLD FRONT
OVER LAKE SUPERIOR. THE FRONT WILL SAG SOUTH ACROSS THE
LAKE FOR THE LATTER HALF OF WEDNESDAY INTO WEDNESDAY NIGHT. HIGH
PRESSURE IS RIGHT ON THE HEELS OF THIS FRONT CAUSING A SHARP
INCREASE IN WINDS BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF
THE NORTH-NORTHEAST WEDNESDAY EVENING. EXPECT WINDS WILL BE SLIGHTLY
LESS FARTHER SOUTH AS THE PRESSURE GRADIENT WILL NOT QUITE AS TIGHT
FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL VEER BACK AROUND TO
THE SOUTHEAST THURSDAY AND THURSDAY NIGHT WHILE DIMINISHING...THEN
BECOME SOUTH TO SOUTHWEST FRIDAY INCREASING INTO THE 25 TO 30 KT
RANGE AS BROAD LOW PRESSURE DEVELOPS OVER THE PLAINS AND CANADIAN
PRAIRIES. WINDS MAY STRENGTHEN TO NEAR GALE FORCE SUNDAY AS THE LOW
STRENGTHENS EAST TOWARD LAKE SUPERIOR THEN SHIFTS EAST.

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 170522
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1222 AM CDT WED SEP 17 2014

.DISCUSSION...
908 PM CDT

ONLY MINOR CHANGES MADE TO THE REST OF TONIGHTS FORECAST. WITH
CLEAR SKIES AND LIGHT WINDS ALLOWING FOR IDEAL RADIATIONAL COOLING
IN THE CONTINUED COOL AND DRY AIR MASS...TEMPERATURES DROPPED AS
MUCH AS 15 DEGREES IN TWO HOURS EARLY THIS EVENING. CONSIDERING
MINIMUM TEMPERATURES LAST NIGHT AND DEW POINTS RUNNING LOWER AT
MOST LOCATIONS...HAVE NUDGED MINIMUM TEMPERATURES DOWN A COUPLE
DEGREES. WOULD EXPECT TO SEE SOME ISOLATED SUB 40 DEGREE READINGS
IN THE USUAL OUTLYING LOCATIONS.

SLIGHTLY HIGHER BOUNDARY LAYER MOISTURE EXISTS IN PARTS OF EAST
CENTRAL IL AND NORTHWEST IN...AS EVIDENCED BY DEW POINTS AND
EARLIER DAYTIME CUMULUS. THIS PROBABLY WILL ALLOW FOR PATCHY
SHALLOW FOG IN THIS AREA. HAVE ADDED INTO THE FORECAST BUT SHOULD
NOT BE A BIG IMPACT.

MTF

//PREV DISCUSSION...
254 PM CDT

TONIGHT...
HIGH PRESSURE HAS BECOME CENTERED OVER THE REGION TODAY...PROVIDING
ABUNDANT SUNSHINE AND LIGHT WINDS. THIS EVENING IS SETTING UP TO BE
A BEAUTIFUL ONE WITH MOSTLY CLEAR SKIES AND NEARLY CALM WINDS FOR
MUCH OF THE OVERNIGHT HOURS. TEMPS WILL RADIATE ONCE AGAIN INTO THE
LOW 40S FOR MUCH OF THE FORECAST AREA...WITH THE EXCEPTION BEING
DOWNTOWN CHICAGO WHERE TEMPS WILL LIKELY HOLD IN THE UPR 40S/ARND
50.

WEDNESDAY THROUGH FRIDAY...
MID-LVL TROUGH WILL REMAIN OVERHEAD THRU WED WITH A CONTINUED LIGHT
NORTHWEST FLOW. AT THE SFC BROAD SFC RIDGING WILL REMAIN IN
PLACE...WITH ABUNDANT SUNSHINE ONCE AGAIN WED AFTN. A BACKDOOR FRONT
WILL SLIP SOUTH ACROSS THE LAKE/NORTHERN GREAT LAKES WED EARLY
MORNING...EVENTUALLY ARRIVING ACROSS NORTHERN IL/NORTHWEST IN LATE
WED NGT/EARLY THUR MORNING. THIS WILL LIKELY PRODUCE AN AREA OF
STRATUS AS IT ARRIVES...HOWEVER AT THIS TIME DRY CONDS ARE EXPECTED
TO PERSIST THRU THUR. THEN ANOTHER SFC RIDGE IS POISED TO SLIDE
SOUTH FROM CENTRAL CANADA...AND LINGER OVER THE REGION THRU EARLY
FRI.

AS THE SFC RIDGE FRI BEGINS TO DRIFT EAST...THE MID-LVL FLOW WILL
BEGIN TO FLATTEN. THIS WILL ALLOW A STEADY TURNING IN THE LLVL FLOW
TO THE SOUTH/SOUTHWEST AND BEGIN ADVECTING WARMER/MOIST AIR INTO THE
REGION FRI NGT. GUIDANCE HAS BEEN STEADILY PUSHING POPS BACK UNTIL
FRI NGT...AND COULD SEE THE SFC RIDGE HOLDING INTO FRI NGT WITH POPS
HOLDING OFF UNTIL EARLY SAT.

TEMPS WED/THUR WILL GENERALLY BE IN THE MID/UPR 60S...WITH A FEW
POINTS POSSIBLY TOUCHING 70 MAINLY SOUTH OF I-80. WITH THE BACKDOOR
FRONT SLIPPING SOUTH IT IS POSSIBLE THE CLOUDS COULD LINGER LONG
ENOUGH THUR THAT TEMPS HOLD IN THE LOW 60S TO POSSIBLY UPR 50S
ACROSS THE NORTHERN IL SECTIONS. THEN FOR FRI TEMPS WILL LIKELY
BEGIN TO CLIMB INTO THE LOW TO POSSIBLY MID 70S. OVERNIGHT LOWS WILL
GENERALLY BE IN THE 40S TO LOW 50S.

CONFIDENCE...HIGH.

SATURDAY THROUGH MONDAY...
ENSEMBLES HAVE COME INTO SLIGHTLY BETTER AGREEMENT IN THE SAT/SUN
TIMEFRAME WITH THE 500MB FLOW REMAINING SOMEWHAT FLAT...WHICH SHOULD
HELP TO BRING THE EXPECTED CHANNEL OF MOISTURE/CONVECTION INTO THE
REGION BUT REMAIN PROGRESSIVE. THEN FOR THE SECOND HALF OF THE
WEEKEND ENSEMBLES RETURN THE MID-LVL RIDGE TO THE WESTERN
CONUS...WITH DOWNSTREAM TROUGHING DEVELOPING OVER THE GREAT LAKES
REGION EARLY NEXT WEEK. IT APPEARS THE BEST DAY FOR CONVECTION WILL
END UP BEING SAT NGT/SUN MORNING. TEMPS WILL LIKELY APPROACH 80 DEG
SAT...AND PERHAPS EVEN THE LOW 80S ACROSS THE SOUTHERN CWFA. HOWEVER
THIS WARM-UP APPEARS TO ONLY BE BRIEF WITH TEMPS SUN BACK INTO THE
LOW 70S AND 60S FOR MON.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* LAKE BREEZE WEDNESDAY AFTERNOON.

BMD

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

ANOTHER QUIET WEATHER DAY IS ON TAP FOR THE REGION WITH HIGH
PRESSURE CENTERED SOUTH OF THE AREA PROVIDING CONTINUED LIGHT FLOW
AND PRIMARILY VFR CONDITIONS OUTSIDE OF SOME PATCHY FOG. FOG IS
EXPECTED TO STAY SOUTH OF THE TERMINALS TONIGHT. A FEW MID LEVEL
CLOUDS MAY DEVELOP MIDDAY WEDNESDAY. A LAKE BREEZE IS ALSO EXPECTED
TO DEVELOP AND SHOULD PUSH ACROSS THE TERMINALS EARLY TO MID
AFTERNOON TURNING WINDS EASTERLY AND BRIEFLY INCREASING SPEEDS INTO
THE 7-9 KT RANGE.

BMD


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

* MEDIUM-HIGH ON LAKE BREEZE TO WITHIN A COUPLE HOURS.
* HIGH ON REMAINING FORECAST ELEMENTS.

BMD

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

* THURSDAY AND FRIDAY...DRY/VFR.
* SATURDAY...CHANCE TSRA. GUSTY SOUTHWEST WINDS.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY...DRY/VFR.

&&

.MARINE...
228 PM CDT

HIGH PRESSURE HAS BUILT ACROSS SOUTHERN LAKE MICHIGAN THIS
AFTERNOON. HOWEVER THE SOUTH TO SOUTHWEST GRADIENT HAS INCREASED
ACROSS THE NORTHERN HALF OF THE LAKE AHEAD OF THE NEXT COLD FRONT
OVER LAKE SUPERIOR. THE FRONT WILL SAG SOUTH ACROSS THE
LAKE FOR THE LATTER HALF OF WEDNESDAY INTO WEDNESDAY NIGHT. HIGH
PRESSURE IS RIGHT ON THE HEELS OF THIS FRONT CAUSING A SHARP
INCREASE IN WINDS BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF
THE NORTH-NORTHEAST WEDNESDAY EVENING. EXPECT WINDS WILL BE SLIGHTLY
LESS FARTHER SOUTH AS THE PRESSURE GRADIENT WILL NOT QUITE AS TIGHT
FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL VEER BACK AROUND TO
THE SOUTHEAST THURSDAY AND THURSDAY NIGHT WHILE DIMINISHING...THEN
BECOME SOUTH TO SOUTHWEST FRIDAY INCREASING INTO THE 25 TO 30 KT
RANGE AS BROAD LOW PRESSURE DEVELOPS OVER THE PLAINS AND CANADIAN
PRAIRIES. WINDS MAY STRENGTHEN TO NEAR GALE FORCE SUNDAY AS THE LOW
STRENGTHENS EAST TOWARD LAKE SUPERIOR THEN SHIFTS EAST.

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 170430
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1130 PM CDT Tue Sep 16 2014

.UPDATE...
ISSUED AT 843 PM CDT TUE SEP 16 2014

Diurnal cumulus cloud cover that was prevalent from about I-57
southward has mostly dissipated this evening as daytime heating
has ended in combination with a 500 mb shortwave ridge bringing
subsidence aloft. Mainly clear skies will prevail through the
early portions of the night then some mid-level cloud cover will
move in late in the night in conjunction with a weak shortwave
trough approaching from the west. Have made minor updates to cloud
cover to account for this. Patchy fog in forecast Wednesday
morning for areas south of I-74 continues to look good as higher
dewpoints and clearer skies expected in that area.

&&

.SHORT TERM...(Tonight)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure continues to build into the Midwest, and a cold front
is draped across the southern US. Tropical Storm Odile is over the
Gulf of California, parked just south of a 500mb ridge.  Forecast
for ILX is dominated by slow warming trend under the high, and
precip chances into next weekend.  Overnight, expecting quiet
weather and temperatures dropping into the mid-upper 40s. Only
concern will be the potential for fog, particularly in the
southeast, where stratocu have trapped some of the higher dwpts in
the region at the sfc.  Patchy fog in the forecast as a result in
the southeast, further north will still be possible, just not really
enough to mention at this time, provided the dwpts continue to mix
and drop a couple degrees.

&&

.LONG TERM...(Wednesday through Tuesday)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure to move off to the east over the Great Lakes on
Thursday and Friday. Cold front from the northern plains to reach
northern IA by early Saturday. Southerly flow ahead of the front
should bring ample moisture back into the area by the day Saturday.

Models differ some on the movement of the remains of Odile into the
southern plains. Moisture appears to be trending to make it into OK,
but should not reach into IL in time as the front should move in and
advect its remains southward.

The cold front is expected to move into region during the day
Saturday, with the main affects and associated precipitation on
Saturday night for central IL. Exiting precipitation on Sunday, so
gradually dropped pops down through the day.

A new high pressure center would then come in behind the front for
the start of next week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
ISSUED AT 1130 PM CDT TUE SEP 16 2014

Surface high pressure meandering across the Midwest will bring
light and variable winds for the next 24 hours. A weak mid-level
shortwave trough crossing Illinois will cause some cloud cover
overnight, but no MVFR ceilings. Fog mention in TAFs continues to
be MVFR from 09Z-12Z, however areas mainly KTAZ-KPRG southward
could see lower values due to higher dewpoints and less cloud
cover expected overnight. Visibility locally down to VLIFR
category is possible. For Wednesday afternoon, scattered cloud
cover expected as daytime heating interacts with low level
moisture, but any local ceilings should remain above MVFR
thresholds.

&&

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

$$

UPDATE...ONTON
SHORT TERM...HJS
LONG TERM...GOETSCH
AVIATION...ONTON







000
FXUS63 KILX 170430
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1130 PM CDT Tue Sep 16 2014

.UPDATE...
ISSUED AT 843 PM CDT TUE SEP 16 2014

Diurnal cumulus cloud cover that was prevalent from about I-57
southward has mostly dissipated this evening as daytime heating
has ended in combination with a 500 mb shortwave ridge bringing
subsidence aloft. Mainly clear skies will prevail through the
early portions of the night then some mid-level cloud cover will
move in late in the night in conjunction with a weak shortwave
trough approaching from the west. Have made minor updates to cloud
cover to account for this. Patchy fog in forecast Wednesday
morning for areas south of I-74 continues to look good as higher
dewpoints and clearer skies expected in that area.

&&

.SHORT TERM...(Tonight)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure continues to build into the Midwest, and a cold front
is draped across the southern US. Tropical Storm Odile is over the
Gulf of California, parked just south of a 500mb ridge.  Forecast
for ILX is dominated by slow warming trend under the high, and
precip chances into next weekend.  Overnight, expecting quiet
weather and temperatures dropping into the mid-upper 40s. Only
concern will be the potential for fog, particularly in the
southeast, where stratocu have trapped some of the higher dwpts in
the region at the sfc.  Patchy fog in the forecast as a result in
the southeast, further north will still be possible, just not really
enough to mention at this time, provided the dwpts continue to mix
and drop a couple degrees.

&&

.LONG TERM...(Wednesday through Tuesday)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure to move off to the east over the Great Lakes on
Thursday and Friday. Cold front from the northern plains to reach
northern IA by early Saturday. Southerly flow ahead of the front
should bring ample moisture back into the area by the day Saturday.

Models differ some on the movement of the remains of Odile into the
southern plains. Moisture appears to be trending to make it into OK,
but should not reach into IL in time as the front should move in and
advect its remains southward.

The cold front is expected to move into region during the day
Saturday, with the main affects and associated precipitation on
Saturday night for central IL. Exiting precipitation on Sunday, so
gradually dropped pops down through the day.

A new high pressure center would then come in behind the front for
the start of next week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
ISSUED AT 1130 PM CDT TUE SEP 16 2014

Surface high pressure meandering across the Midwest will bring
light and variable winds for the next 24 hours. A weak mid-level
shortwave trough crossing Illinois will cause some cloud cover
overnight, but no MVFR ceilings. Fog mention in TAFs continues to
be MVFR from 09Z-12Z, however areas mainly KTAZ-KPRG southward
could see lower values due to higher dewpoints and less cloud
cover expected overnight. Visibility locally down to VLIFR
category is possible. For Wednesday afternoon, scattered cloud
cover expected as daytime heating interacts with low level
moisture, but any local ceilings should remain above MVFR
thresholds.

&&

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

$$

UPDATE...ONTON
SHORT TERM...HJS
LONG TERM...GOETSCH
AVIATION...ONTON








000
FXUS63 KLOT 170303
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1003 PM CDT TUE SEP 16 2014

.DISCUSSION...
908 PM CDT

ONLY MINOR CHANGES MADE TO THE REST OF TONIGHTS FORECAST. WITH
CLEAR SKIES AND LIGHT WINDS ALLOWING FOR IDEAL RADIATIONAL COOLING
IN THE CONTINUED COOL AND DRY AIR MASS...TEMPERATURES DROPPED AS
MUCH AS 15 DEGREES IN TWO HOURS EARLY THIS EVENING. CONSIDERING
MINIMUM TEMPERATURES LAST NIGHT AND DEW POINTS RUNNING LOWER AT
MOST LOCATIONS...HAVE NUDGED MINIMUM TEMPERATURES DOWN A COUPLE
DEGREES. WOULD EXPECT TO SEE SOME ISOLATED SUB 40 DEGREE READINGS
IN THE USUAL OUTLYING LOCATIONS.

SLIGHTLY HIGHER BOUNDARY LAYER MOISTURE EXISTS IN PARTS OF EAST
CENTRAL IL AND NORTHWEST IN...AS EVIDENCED BY DEW POINTS AND
EARLIER DAYTIME CUMULUS. THIS PROBABLY WILL ALLOW FOR PATCHY
SHALLOW FOG IN THIS AREA. HAVE ADDED INTO THE FORECAST BUT SHOULD
NOT BE A BIG IMPACT.

MTF

//PREV DISCUSSION...
254 PM CDT

TONIGHT...
HIGH PRESSURE HAS BECOME CENTERED OVER THE REGION TODAY...PROVIDING
ABUNDANT SUNSHINE AND LIGHT WINDS. THIS EVENING IS SETTING UP TO BE
A BEAUTIFUL ONE WITH MOSTLY CLEAR SKIES AND NEARLY CALM WINDS FOR
MUCH OF THE OVERNIGHT HOURS. TEMPS WILL RADIATE ONCE AGAIN INTO THE
LOW 40S FOR MUCH OF THE FORECAST AREA...WITH THE EXCEPTION BEING
DOWNTOWN CHICAGO WHERE TEMPS WILL LIKELY HOLD IN THE UPR 40S/ARND
50.

WEDNESDAY THROUGH FRIDAY...
MID-LVL TROUGH WILL REMAIN OVERHEAD THRU WED WITH A CONTINUED LIGHT
NORTHWEST FLOW. AT THE SFC BROAD SFC RIDGING WILL REMAIN IN
PLACE...WITH ABUNDANT SUNSHINE ONCE AGAIN WED AFTN. A BACKDOOR FRONT
WILL SLIP SOUTH ACROSS THE LAKE/NORTHERN GREAT LAKES WED EARLY
MORNING...EVENTUALLY ARRIVING ACROSS NORTHERN IL/NORTHWEST IN LATE
WED NGT/EARLY THUR MORNING. THIS WILL LIKELY PRODUCE AN AREA OF
STRATUS AS IT ARRIVES...HOWEVER AT THIS TIME DRY CONDS ARE EXPECTED
TO PERSIST THRU THUR. THEN ANOTHER SFC RIDGE IS POISED TO SLIDE
SOUTH FROM CENTRAL CANADA...AND LINGER OVER THE REGION THRU EARLY
FRI.

AS THE SFC RIDGE FRI BEGINS TO DRIFT EAST...THE MID-LVL FLOW WILL
BEGIN TO FLATTEN. THIS WILL ALLOW A STEADY TURNING IN THE LLVL FLOW
TO THE SOUTH/SOUTHWEST AND BEGIN ADVECTING WARMER/MOIST AIR INTO THE
REGION FRI NGT. GUIDANCE HAS BEEN STEADILY PUSHING POPS BACK UNTIL
FRI NGT...AND COULD SEE THE SFC RIDGE HOLDING INTO FRI NGT WITH POPS
HOLDING OFF UNTIL EARLY SAT.

TEMPS WED/THUR WILL GENERALLY BE IN THE MID/UPR 60S...WITH A FEW
POINTS POSSIBLY TOUCHING 70 MAINLY SOUTH OF I-80. WITH THE BACKDOOR
FRONT SLIPPING SOUTH IT IS POSSIBLE THE CLOUDS COULD LINGER LONG
ENOUGH THUR THAT TEMPS HOLD IN THE LOW 60S TO POSSIBLY UPR 50S
ACROSS THE NORTHERN IL SECTIONS. THEN FOR FRI TEMPS WILL LIKELY
BEGIN TO CLIMB INTO THE LOW TO POSSIBLY MID 70S. OVERNIGHT LOWS WILL
GENERALLY BE IN THE 40S TO LOW 50S.

CONFIDENCE...HIGH.

SATURDAY THROUGH MONDAY...
ENSEMBLES HAVE COME INTO SLIGHTLY BETTER AGREEMENT IN THE SAT/SUN
TIMEFRAME WITH THE 500MB FLOW REMAINING SOMEWHAT FLAT...WHICH SHOULD
HELP TO BRING THE EXPECTED CHANNEL OF MOISTURE/CONVECTION INTO THE
REGION BUT REMAIN PROGRESSIVE. THEN FOR THE SECOND HALF OF THE
WEEKEND ENSEMBLES RETURN THE MID-LVL RIDGE TO THE WESTERN
CONUS...WITH DOWNSTREAM TROUGHING DEVELOPING OVER THE GREAT LAKES
REGION EARLY NEXT WEEK. IT APPEARS THE BEST DAY FOR CONVECTION WILL
END UP BEING SAT NGT/SUN MORNING. TEMPS WILL LIKELY APPROACH 80 DEG
SAT...AND PERHAPS EVEN THE LOW 80S ACROSS THE SOUTHERN CWFA. HOWEVER
THIS WARM-UP APPEARS TO ONLY BE BRIEF WITH TEMPS SUN BACK INTO THE
LOW 70S AND 60S FOR MON.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* LAKE BREEZE LATE WEDNESDAY AFTERNOON. CMS

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

THE LAKE BREEZE HAS SURGED INLAND AND IS CURRENTLY MOVING WEST
THROUGH ORD/MDW. SPEEDS MAY REACH 8-10KTS WITH ITS PASSAGE BUT
THEN DIMINISH BACK TO 4-6KTS FOR A FEW HOURS. HIGH PRESSURE OVER
THE REGION TONIGHT WILL ALLOW WINDS TO BECOME LIGHT AND VARIABLE
OR CALM BY LATE EVENING. WINDS WILL THEN BECOME LIGHT SOUTHWEST
OR WEST WEDNESDAY MORNING WITH THE WEAK GRADIENT REMAINING AS THE
CENTER OF THE HIGH SHIFTS EAST. ANOTHER LAKE BREEZE SHOULD
DEVELOP WEDNESDAY AFTERNOON...POSSIBLY REACHING ORD/MDW BY LATE
AFTERNOON. CMS

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

* MEDIUM FOR A LAKE BREEZE REACHING ORD/MDW WEDNESDAY AFTERNOON.
  CMS

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

* THURSDAY AND FRIDAY...DRY/VFR.
* SATURDAY...CHANCE TSRA. GUSTY SOUTHWEST WINDS.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY...DRY/VFR.

&&

.MARINE...
228 PM CDT

HIGH PRESSURE HAS BUILT ACROSS SOUTHERN LAKE MICHIGAN THIS
AFTERNOON. HOWEVER THE SOUTH TO SOUTHWEST GRADIENT HAS INCREASED
ACROSS THE NORTHERN HALF OF THE LAKE AHEAD OF THE NEXT COLD FRONT
OVER LAKE SUPERIOR. THE FRONT WILL SAG SOUTH ACROSS THE
LAKE FOR THE LATTER HALF OF WEDNESDAY INTO WEDNESDAY NIGHT. HIGH
PRESSURE IS RIGHT ON THE HEELS OF THIS FRONT CAUSING A SHARP
INCREASE IN WINDS BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF
THE NORTH-NORTHEAST WEDNESDAY EVENING. EXPECT WINDS WILL BE SLIGHTLY
LESS FARTHER SOUTH AS THE PRESSURE GRADIENT WILL NOT QUITE AS TIGHT
FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL VEER BACK AROUND TO
THE SOUTHEAST THURSDAY AND THURSDAY NIGHT WHILE DIMINISHING...THEN
BECOME SOUTH TO SOUTHWEST FRIDAY INCREASING INTO THE 25 TO 30 KT
RANGE AS BROAD LOW PRESSURE DEVELOPS OVER THE PLAINS AND CANADIAN
PRAIRIES. WINDS MAY STRENGTHEN TO NEAR GALE FORCE SUNDAY AS THE LOW
STRENGTHENS EAST TOWARD LAKE SUPERIOR THEN SHIFTS EAST.

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 170209 AAA
AFDLOT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
909 PM CDT TUE SEP 16 2014

.DISCUSSION...
908 PM CDT

ONLY MINOR CHANGES MADE TO THE REST OF TONIGHTS FORECAST. WITH
CLEAR SKIES AND LIGHT WINDS ALLOWING FOR IDEAL RADIATIONAL COOLING
IN THE CONTINUED COOL AND DRY AIR MASS...TEMPERATURES DROPPED AS
MUCH AS 15 DEGREES IN TWO HOURS EARLY THIS EVENING. CONSIDERING
MINIMUM TEMPERATURES LAST NIGHT AND DEW POINTS RUNNING LOWER AT
MOST LOCATIONS...HAVE NUDGED MINIMUM TEMPERATURES DOWN A COUPLE
DEGREES. WOULD EXPECT TO SEE SOME ISOLATED SUB 40 DEGREE READINGS
IN THE USUAL OUTLYING LOCATIONS.

SLIGHTLY HIGHER BOUNDARY LAYER MOISTURE EXISTS IN PARTS OF EAST
CENTRAL IL AND NORTHWEST IN...AS EVIDENCED BY DEW POINTS AND
EARLIER DAYTIME CUMULUS. THIS PROBABLY WILL ALLOW FOR PATCHY
SHALLOW FOG IN THIS AREA. HAVE ADDED INTO THE FORECAST BUT SHOULD
NOT BE A BIG IMPACT.

MTF

&&

.PREV DISCUSSION...
254 PM CDT

TONIGHT...
HIGH PRESSURE HAS BECOME CENTERED OVER THE REGION TODAY...PROVIDING
ABUNDANT SUNSHINE AND LIGHT WINDS. THIS EVENING IS SETTING UP TO BE
A BEAUTIFUL ONE WITH MOSTLY CLEAR SKIES AND NEARLY CALM WINDS FOR
MUCH OF THE OVERNIGHT HOURS. TEMPS WILL RADIATE ONCE AGAIN INTO THE
LOW 40S FOR MUCH OF THE FORECAST AREA...WITH THE EXCEPTION BEING
DOWNTOWN CHICAGO WHERE TEMPS WILL LIKELY HOLD IN THE UPR 40S/ARND
50.

WEDNESDAY THROUGH FRIDAY...
MID-LVL TROUGH WILL REMAIN OVERHEAD THRU WED WITH A CONTINUED LIGHT
NORTHWEST FLOW. AT THE SFC BROAD SFC RIDGING WILL REMAIN IN
PLACE...WITH ABUNDANT SUNSHINE ONCE AGAIN WED AFTN. A BACKDOOR FRONT
WILL SLIP SOUTH ACROSS THE LAKE/NORTHERN GREAT LAKES WED EARLY
MORNING...EVENTUALLY ARRIVING ACROSS NORTHERN IL/NORTHWEST IN LATE
WED NGT/EARLY THUR MORNING. THIS WILL LIKELY PRODUCE AN AREA OF
STRATUS AS IT ARRIVES...HOWEVER AT THIS TIME DRY CONDS ARE EXPECTED
TO PERSIST THRU THUR. THEN ANOTHER SFC RIDGE IS POISED TO SLIDE
SOUTH FROM CENTRAL CANADA...AND LINGER OVER THE REGION THRU EARLY
FRI.

AS THE SFC RIDGE FRI BEGINS TO DRIFT EAST...THE MID-LVL FLOW WILL
BEGIN TO FLATTEN. THIS WILL ALLOW A STEADY TURNING IN THE LLVL FLOW
TO THE SOUTH/SOUTHWEST AND BEGIN ADVECTING WARMER/MOIST AIR INTO THE
REGION FRI NGT. GUIDANCE HAS BEEN STEADILY PUSHING POPS BACK UNTIL
FRI NGT...AND COULD SEE THE SFC RIDGE HOLDING INTO FRI NGT WITH POPS
HOLDING OFF UNTIL EARLY SAT.

TEMPS WED/THUR WILL GENERALLY BE IN THE MID/UPR 60S...WITH A FEW
POINTS POSSIBLY TOUCHING 70 MAINLY SOUTH OF I-80. WITH THE BACKDOOR
FRONT SLIPPING SOUTH IT IS POSSIBLE THE CLOUDS COULD LINGER LONG
ENOUGH THUR THAT TEMPS HOLD IN THE LOW 60S TO POSSIBLY UPR 50S
ACROSS THE NORTHERN IL SECTIONS. THEN FOR FRI TEMPS WILL LIKELY
BEGIN TO CLIMB INTO THE LOW TO POSSIBLY MID 70S. OVERNIGHT LOWS WILL
GENERALLY BE IN THE 40S TO LOW 50S.

CONFIDENCE...HIGH.

SATURDAY THROUGH MONDAY...
ENSEMBLES HAVE COME INTO SLIGHTLY BETTER AGREEMENT IN THE SAT/SUN
TIMEFRAME WITH THE 500MB FLOW REMAINING SOMEWHAT FLAT...WHICH SHOULD
HELP TO BRING THE EXPECTED CHANNEL OF MOISTURE/CONVECTION INTO THE
REGION BUT REMAIN PROGRESSIVE. THEN FOR THE SECOND HALF OF THE
WEEKEND ENSEMBLES RETURN THE MID-LVL RIDGE TO THE WESTERN
CONUS...WITH DOWNSTREAM TROUGHING DEVELOPING OVER THE GREAT LAKES
REGION EARLY NEXT WEEK. IT APPEARS THE BEST DAY FOR CONVECTION WILL
END UP BEING SAT NGT/SUN MORNING. TEMPS WILL LIKELY APPROACH 80 DEG
SAT...AND PERHAPS EVEN THE LOW 80S ACROSS THE SOUTHERN CWFA. HOWEVER
THIS WARM-UP APPEARS TO ONLY BE BRIEF WITH TEMPS SUN BACK INTO THE
LOW 70S AND 60S FOR MON.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* LAKE BREEZE EARLY THIS EVENING.
* LAKE BREEZE LATE WEDNESDAY AFTERNOON. CMS

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

THE LAKE BREEZE HAS SURGED INLAND AND IS CURRENTLY MOVING WEST
THROUGH ORD/MDW. SPEEDS MAY REACH 8-10KTS WITH ITS PASSAGE BUT
THEN DIMINISH BACK TO 4-6KTS FOR A FEW HOURS. HIGH PRESSURE OVER
THE REGION TONIGHT WILL ALLOW WINDS TO BECOME LIGHT AND VARIABLE
OR CALM BY LATE EVENING. WINDS WILL THEN BECOME LIGHT SOUTHWEST
OR WEST WEDNESDAY MORNING WITH THE WEAK GRADIENT REMAINING AS THE
CENTER OF THE HIGH SHIFTS EAST. ANOTHER LAKE BREEZE SHOULD
DEVELOP WEDNESDAY AFTERNOON...POSSIBLY REACHING ORD/MDW BY LATE
AFTERNOON. CMS

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

* MEDIUM FOR A LAKE BREEZE REACHING ORD/MDW WEDNESDAY AFTERNOON.
  CMS

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

* THURSDAY AND FRIDAY...DRY/VFR.
* SATURDAY...CHANCE TSRA. GUSTY SOUTHWEST WINDS.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY...DRY/VFR.

&&

.MARINE...
228 PM CDT

HIGH PRESSURE HAS BUILT ACROSS SOUTHERN LAKE MICHIGAN THIS
AFTERNOON. HOWEVER THE SOUTH TO SOUTHWEST GRADIENT HAS INCREASED
ACROSS THE NORTHERN HALF OF THE LAKE AHEAD OF THE NEXT COLD FRONT
OVER LAKE SUPERIOR. THE FRONT WILL SAG SOUTH ACROSS THE
LAKE FOR THE LATTER HALF OF WEDNESDAY INTO WEDNESDAY NIGHT. HIGH
PRESSURE IS RIGHT ON THE HEELS OF THIS FRONT CAUSING A SHARP
INCREASE IN WINDS BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF
THE NORTH-NORTHEAST WEDNESDAY EVENING. EXPECT WINDS WILL BE SLIGHTLY
LESS FARTHER SOUTH AS THE PRESSURE GRADIENT WILL NOT QUITE AS TIGHT
FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL VEER BACK AROUND TO
THE SOUTHEAST THURSDAY AND THURSDAY NIGHT WHILE DIMINISHING...THEN
BECOME SOUTH TO SOUTHWEST FRIDAY INCREASING INTO THE 25 TO 30 KT
RANGE AS BROAD LOW PRESSURE DEVELOPS OVER THE PLAINS AND CANADIAN
PRAIRIES. WINDS MAY STRENGTHEN TO NEAR GALE FORCE SUNDAY AS THE LOW
STRENGTHENS EAST TOWARD LAKE SUPERIOR THEN SHIFTS EAST.

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 170209 AAA
AFDLOT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
909 PM CDT TUE SEP 16 2014

.DISCUSSION...
908 PM CDT

ONLY MINOR CHANGES MADE TO THE REST OF TONIGHTS FORECAST. WITH
CLEAR SKIES AND LIGHT WINDS ALLOWING FOR IDEAL RADIATIONAL COOLING
IN THE CONTINUED COOL AND DRY AIR MASS...TEMPERATURES DROPPED AS
MUCH AS 15 DEGREES IN TWO HOURS EARLY THIS EVENING. CONSIDERING
MINIMUM TEMPERATURES LAST NIGHT AND DEW POINTS RUNNING LOWER AT
MOST LOCATIONS...HAVE NUDGED MINIMUM TEMPERATURES DOWN A COUPLE
DEGREES. WOULD EXPECT TO SEE SOME ISOLATED SUB 40 DEGREE READINGS
IN THE USUAL OUTLYING LOCATIONS.

SLIGHTLY HIGHER BOUNDARY LAYER MOISTURE EXISTS IN PARTS OF EAST
CENTRAL IL AND NORTHWEST IN...AS EVIDENCED BY DEW POINTS AND
EARLIER DAYTIME CUMULUS. THIS PROBABLY WILL ALLOW FOR PATCHY
SHALLOW FOG IN THIS AREA. HAVE ADDED INTO THE FORECAST BUT SHOULD
NOT BE A BIG IMPACT.

MTF

&&

.PREV DISCUSSION...
254 PM CDT

TONIGHT...
HIGH PRESSURE HAS BECOME CENTERED OVER THE REGION TODAY...PROVIDING
ABUNDANT SUNSHINE AND LIGHT WINDS. THIS EVENING IS SETTING UP TO BE
A BEAUTIFUL ONE WITH MOSTLY CLEAR SKIES AND NEARLY CALM WINDS FOR
MUCH OF THE OVERNIGHT HOURS. TEMPS WILL RADIATE ONCE AGAIN INTO THE
LOW 40S FOR MUCH OF THE FORECAST AREA...WITH THE EXCEPTION BEING
DOWNTOWN CHICAGO WHERE TEMPS WILL LIKELY HOLD IN THE UPR 40S/ARND
50.

WEDNESDAY THROUGH FRIDAY...
MID-LVL TROUGH WILL REMAIN OVERHEAD THRU WED WITH A CONTINUED LIGHT
NORTHWEST FLOW. AT THE SFC BROAD SFC RIDGING WILL REMAIN IN
PLACE...WITH ABUNDANT SUNSHINE ONCE AGAIN WED AFTN. A BACKDOOR FRONT
WILL SLIP SOUTH ACROSS THE LAKE/NORTHERN GREAT LAKES WED EARLY
MORNING...EVENTUALLY ARRIVING ACROSS NORTHERN IL/NORTHWEST IN LATE
WED NGT/EARLY THUR MORNING. THIS WILL LIKELY PRODUCE AN AREA OF
STRATUS AS IT ARRIVES...HOWEVER AT THIS TIME DRY CONDS ARE EXPECTED
TO PERSIST THRU THUR. THEN ANOTHER SFC RIDGE IS POISED TO SLIDE
SOUTH FROM CENTRAL CANADA...AND LINGER OVER THE REGION THRU EARLY
FRI.

AS THE SFC RIDGE FRI BEGINS TO DRIFT EAST...THE MID-LVL FLOW WILL
BEGIN TO FLATTEN. THIS WILL ALLOW A STEADY TURNING IN THE LLVL FLOW
TO THE SOUTH/SOUTHWEST AND BEGIN ADVECTING WARMER/MOIST AIR INTO THE
REGION FRI NGT. GUIDANCE HAS BEEN STEADILY PUSHING POPS BACK UNTIL
FRI NGT...AND COULD SEE THE SFC RIDGE HOLDING INTO FRI NGT WITH POPS
HOLDING OFF UNTIL EARLY SAT.

TEMPS WED/THUR WILL GENERALLY BE IN THE MID/UPR 60S...WITH A FEW
POINTS POSSIBLY TOUCHING 70 MAINLY SOUTH OF I-80. WITH THE BACKDOOR
FRONT SLIPPING SOUTH IT IS POSSIBLE THE CLOUDS COULD LINGER LONG
ENOUGH THUR THAT TEMPS HOLD IN THE LOW 60S TO POSSIBLY UPR 50S
ACROSS THE NORTHERN IL SECTIONS. THEN FOR FRI TEMPS WILL LIKELY
BEGIN TO CLIMB INTO THE LOW TO POSSIBLY MID 70S. OVERNIGHT LOWS WILL
GENERALLY BE IN THE 40S TO LOW 50S.

CONFIDENCE...HIGH.

SATURDAY THROUGH MONDAY...
ENSEMBLES HAVE COME INTO SLIGHTLY BETTER AGREEMENT IN THE SAT/SUN
TIMEFRAME WITH THE 500MB FLOW REMAINING SOMEWHAT FLAT...WHICH SHOULD
HELP TO BRING THE EXPECTED CHANNEL OF MOISTURE/CONVECTION INTO THE
REGION BUT REMAIN PROGRESSIVE. THEN FOR THE SECOND HALF OF THE
WEEKEND ENSEMBLES RETURN THE MID-LVL RIDGE TO THE WESTERN
CONUS...WITH DOWNSTREAM TROUGHING DEVELOPING OVER THE GREAT LAKES
REGION EARLY NEXT WEEK. IT APPEARS THE BEST DAY FOR CONVECTION WILL
END UP BEING SAT NGT/SUN MORNING. TEMPS WILL LIKELY APPROACH 80 DEG
SAT...AND PERHAPS EVEN THE LOW 80S ACROSS THE SOUTHERN CWFA. HOWEVER
THIS WARM-UP APPEARS TO ONLY BE BRIEF WITH TEMPS SUN BACK INTO THE
LOW 70S AND 60S FOR MON.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* LAKE BREEZE EARLY THIS EVENING.
* LAKE BREEZE LATE WEDNESDAY AFTERNOON. CMS

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

THE LAKE BREEZE HAS SURGED INLAND AND IS CURRENTLY MOVING WEST
THROUGH ORD/MDW. SPEEDS MAY REACH 8-10KTS WITH ITS PASSAGE BUT
THEN DIMINISH BACK TO 4-6KTS FOR A FEW HOURS. HIGH PRESSURE OVER
THE REGION TONIGHT WILL ALLOW WINDS TO BECOME LIGHT AND VARIABLE
OR CALM BY LATE EVENING. WINDS WILL THEN BECOME LIGHT SOUTHWEST
OR WEST WEDNESDAY MORNING WITH THE WEAK GRADIENT REMAINING AS THE
CENTER OF THE HIGH SHIFTS EAST. ANOTHER LAKE BREEZE SHOULD
DEVELOP WEDNESDAY AFTERNOON...POSSIBLY REACHING ORD/MDW BY LATE
AFTERNOON. CMS

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

* MEDIUM FOR A LAKE BREEZE REACHING ORD/MDW WEDNESDAY AFTERNOON.
  CMS

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

* THURSDAY AND FRIDAY...DRY/VFR.
* SATURDAY...CHANCE TSRA. GUSTY SOUTHWEST WINDS.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY...DRY/VFR.

&&

.MARINE...
228 PM CDT

HIGH PRESSURE HAS BUILT ACROSS SOUTHERN LAKE MICHIGAN THIS
AFTERNOON. HOWEVER THE SOUTH TO SOUTHWEST GRADIENT HAS INCREASED
ACROSS THE NORTHERN HALF OF THE LAKE AHEAD OF THE NEXT COLD FRONT
OVER LAKE SUPERIOR. THE FRONT WILL SAG SOUTH ACROSS THE
LAKE FOR THE LATTER HALF OF WEDNESDAY INTO WEDNESDAY NIGHT. HIGH
PRESSURE IS RIGHT ON THE HEELS OF THIS FRONT CAUSING A SHARP
INCREASE IN WINDS BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF
THE NORTH-NORTHEAST WEDNESDAY EVENING. EXPECT WINDS WILL BE SLIGHTLY
LESS FARTHER SOUTH AS THE PRESSURE GRADIENT WILL NOT QUITE AS TIGHT
FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL VEER BACK AROUND TO
THE SOUTHEAST THURSDAY AND THURSDAY NIGHT WHILE DIMINISHING...THEN
BECOME SOUTH TO SOUTHWEST FRIDAY INCREASING INTO THE 25 TO 30 KT
RANGE AS BROAD LOW PRESSURE DEVELOPS OVER THE PLAINS AND CANADIAN
PRAIRIES. WINDS MAY STRENGTHEN TO NEAR GALE FORCE SUNDAY AS THE LOW
STRENGTHENS EAST TOWARD LAKE SUPERIOR THEN SHIFTS EAST.

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 170143
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
843 PM CDT Tue Sep 16 2014

.UPDATE...
ISSUED AT 843 PM CDT TUE SEP 16 2014

Diurnal cumulus cloud cover that was prevalent from about I-57
southward has mostly dissipated this evening as daytime heating
has ended in combination with a 500 mb shortwave ridge bringing
subsidence aloft. Mainly clear skies will prevail through the
early portions of the night then some mid-level cloud cover will
move in late in the night in conjunction with a weak shortwave
trough approaching from the west. Have made minor updates to cloud
cover to account for this. Patchy fog in forecast Wednesday
morning for areas south of I-74 continues to look good as higher
dewpoints and clearer skies expected in that area.

&&

.SHORT TERM...(Tonight)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure continues to build into the Midwest, and a cold front
is draped across the southern US. Tropical Storm Odile is over the
Gulf of California, parked just south of a 500mb ridge.  Forecast
for ILX is dominated by slow warming trend under the high, and
precip chances into next weekend.  Overnight, expecting quiet
weather and temperatures dropping into the mid-upper 40s. Only
concern will be the potential for fog, particularly in the
southeast, where stratocu have trapped some of the higher dwpts in
the region at the sfc.  Patchy fog in the forecast as a result in
the southeast, further north will still be possible, just not really
enough to mention at this time, provided the dwpts continue to mix
and drop a couple degrees.

&&

.LONG TERM...(Wednesday through Tuesday)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure to move off to the east over the Great Lakes on
Thursday and Friday. Cold front from the northern plains to reach
northern IA by early Saturday. Southerly flow ahead of the front
should bring ample moisture back into the area by the day Saturday.

Models differ some on the movement of the remains of Odile into the
southern plains. Moisture appears to be trending to make it into OK,
but should not reach into IL in time as the front should move in and
advect its remains southward.

The cold front is expected to move into region during the day
Saturday, with the main affects and associated precipitation on
Saturday night for central IL. Exiting precipitation on Sunday, so
gradually dropped pops down through the day.

A new high pressure center would then come in behind the front for
the start of next week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
ISSUED AT 613 PM CDT TUE SEP 16 2014

Surface high pressure meandering across the Midwest will bring
light and variable winds for the next 24 hours. A weak mid-level
shortwave trough crossing Illinois will cause some cloud cover
overnight, but no MVFR ceilings. Fog mention in TAFs continues to
be MVFR from 09Z-12Z, however areas KTAZ-KPRG southward could see
lower values due to higher dewpoints and less cloud cover expected
overnight. For Wednesday afternoon, scattered cloud cover
expected as daytime heating interacts with low level
moisture, but any local ceilings should remain above MVFR
thresholds.


&&

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

$$

UPDATE...ONTON
SHORT TERM...HJS
LONG TERM...GOETSCH
AVIATION...ONTON







000
FXUS63 KILX 170143
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
843 PM CDT Tue Sep 16 2014

.UPDATE...
ISSUED AT 843 PM CDT TUE SEP 16 2014

Diurnal cumulus cloud cover that was prevalent from about I-57
southward has mostly dissipated this evening as daytime heating
has ended in combination with a 500 mb shortwave ridge bringing
subsidence aloft. Mainly clear skies will prevail through the
early portions of the night then some mid-level cloud cover will
move in late in the night in conjunction with a weak shortwave
trough approaching from the west. Have made minor updates to cloud
cover to account for this. Patchy fog in forecast Wednesday
morning for areas south of I-74 continues to look good as higher
dewpoints and clearer skies expected in that area.

&&

.SHORT TERM...(Tonight)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure continues to build into the Midwest, and a cold front
is draped across the southern US. Tropical Storm Odile is over the
Gulf of California, parked just south of a 500mb ridge.  Forecast
for ILX is dominated by slow warming trend under the high, and
precip chances into next weekend.  Overnight, expecting quiet
weather and temperatures dropping into the mid-upper 40s. Only
concern will be the potential for fog, particularly in the
southeast, where stratocu have trapped some of the higher dwpts in
the region at the sfc.  Patchy fog in the forecast as a result in
the southeast, further north will still be possible, just not really
enough to mention at this time, provided the dwpts continue to mix
and drop a couple degrees.

&&

.LONG TERM...(Wednesday through Tuesday)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure to move off to the east over the Great Lakes on
Thursday and Friday. Cold front from the northern plains to reach
northern IA by early Saturday. Southerly flow ahead of the front
should bring ample moisture back into the area by the day Saturday.

Models differ some on the movement of the remains of Odile into the
southern plains. Moisture appears to be trending to make it into OK,
but should not reach into IL in time as the front should move in and
advect its remains southward.

The cold front is expected to move into region during the day
Saturday, with the main affects and associated precipitation on
Saturday night for central IL. Exiting precipitation on Sunday, so
gradually dropped pops down through the day.

A new high pressure center would then come in behind the front for
the start of next week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
ISSUED AT 613 PM CDT TUE SEP 16 2014

Surface high pressure meandering across the Midwest will bring
light and variable winds for the next 24 hours. A weak mid-level
shortwave trough crossing Illinois will cause some cloud cover
overnight, but no MVFR ceilings. Fog mention in TAFs continues to
be MVFR from 09Z-12Z, however areas KTAZ-KPRG southward could see
lower values due to higher dewpoints and less cloud cover expected
overnight. For Wednesday afternoon, scattered cloud cover
expected as daytime heating interacts with low level
moisture, but any local ceilings should remain above MVFR
thresholds.


&&

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

$$

UPDATE...ONTON
SHORT TERM...HJS
LONG TERM...GOETSCH
AVIATION...ONTON







000
FXUS63 KILX 170143
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
843 PM CDT Tue Sep 16 2014

.UPDATE...
ISSUED AT 843 PM CDT TUE SEP 16 2014

Diurnal cumulus cloud cover that was prevalent from about I-57
southward has mostly dissipated this evening as daytime heating
has ended in combination with a 500 mb shortwave ridge bringing
subsidence aloft. Mainly clear skies will prevail through the
early portions of the night then some mid-level cloud cover will
move in late in the night in conjunction with a weak shortwave
trough approaching from the west. Have made minor updates to cloud
cover to account for this. Patchy fog in forecast Wednesday
morning for areas south of I-74 continues to look good as higher
dewpoints and clearer skies expected in that area.

&&

.SHORT TERM...(Tonight)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure continues to build into the Midwest, and a cold front
is draped across the southern US. Tropical Storm Odile is over the
Gulf of California, parked just south of a 500mb ridge.  Forecast
for ILX is dominated by slow warming trend under the high, and
precip chances into next weekend.  Overnight, expecting quiet
weather and temperatures dropping into the mid-upper 40s. Only
concern will be the potential for fog, particularly in the
southeast, where stratocu have trapped some of the higher dwpts in
the region at the sfc.  Patchy fog in the forecast as a result in
the southeast, further north will still be possible, just not really
enough to mention at this time, provided the dwpts continue to mix
and drop a couple degrees.

&&

.LONG TERM...(Wednesday through Tuesday)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure to move off to the east over the Great Lakes on
Thursday and Friday. Cold front from the northern plains to reach
northern IA by early Saturday. Southerly flow ahead of the front
should bring ample moisture back into the area by the day Saturday.

Models differ some on the movement of the remains of Odile into the
southern plains. Moisture appears to be trending to make it into OK,
but should not reach into IL in time as the front should move in and
advect its remains southward.

The cold front is expected to move into region during the day
Saturday, with the main affects and associated precipitation on
Saturday night for central IL. Exiting precipitation on Sunday, so
gradually dropped pops down through the day.

A new high pressure center would then come in behind the front for
the start of next week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
ISSUED AT 613 PM CDT TUE SEP 16 2014

Surface high pressure meandering across the Midwest will bring
light and variable winds for the next 24 hours. A weak mid-level
shortwave trough crossing Illinois will cause some cloud cover
overnight, but no MVFR ceilings. Fog mention in TAFs continues to
be MVFR from 09Z-12Z, however areas KTAZ-KPRG southward could see
lower values due to higher dewpoints and less cloud cover expected
overnight. For Wednesday afternoon, scattered cloud cover
expected as daytime heating interacts with low level
moisture, but any local ceilings should remain above MVFR
thresholds.


&&

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

$$

UPDATE...ONTON
SHORT TERM...HJS
LONG TERM...GOETSCH
AVIATION...ONTON







000
FXUS63 KILX 170143
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
843 PM CDT Tue Sep 16 2014

.UPDATE...
ISSUED AT 843 PM CDT TUE SEP 16 2014

Diurnal cumulus cloud cover that was prevalent from about I-57
southward has mostly dissipated this evening as daytime heating
has ended in combination with a 500 mb shortwave ridge bringing
subsidence aloft. Mainly clear skies will prevail through the
early portions of the night then some mid-level cloud cover will
move in late in the night in conjunction with a weak shortwave
trough approaching from the west. Have made minor updates to cloud
cover to account for this. Patchy fog in forecast Wednesday
morning for areas south of I-74 continues to look good as higher
dewpoints and clearer skies expected in that area.

&&

.SHORT TERM...(Tonight)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure continues to build into the Midwest, and a cold front
is draped across the southern US. Tropical Storm Odile is over the
Gulf of California, parked just south of a 500mb ridge.  Forecast
for ILX is dominated by slow warming trend under the high, and
precip chances into next weekend.  Overnight, expecting quiet
weather and temperatures dropping into the mid-upper 40s. Only
concern will be the potential for fog, particularly in the
southeast, where stratocu have trapped some of the higher dwpts in
the region at the sfc.  Patchy fog in the forecast as a result in
the southeast, further north will still be possible, just not really
enough to mention at this time, provided the dwpts continue to mix
and drop a couple degrees.

&&

.LONG TERM...(Wednesday through Tuesday)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure to move off to the east over the Great Lakes on
Thursday and Friday. Cold front from the northern plains to reach
northern IA by early Saturday. Southerly flow ahead of the front
should bring ample moisture back into the area by the day Saturday.

Models differ some on the movement of the remains of Odile into the
southern plains. Moisture appears to be trending to make it into OK,
but should not reach into IL in time as the front should move in and
advect its remains southward.

The cold front is expected to move into region during the day
Saturday, with the main affects and associated precipitation on
Saturday night for central IL. Exiting precipitation on Sunday, so
gradually dropped pops down through the day.

A new high pressure center would then come in behind the front for
the start of next week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
ISSUED AT 613 PM CDT TUE SEP 16 2014

Surface high pressure meandering across the Midwest will bring
light and variable winds for the next 24 hours. A weak mid-level
shortwave trough crossing Illinois will cause some cloud cover
overnight, but no MVFR ceilings. Fog mention in TAFs continues to
be MVFR from 09Z-12Z, however areas KTAZ-KPRG southward could see
lower values due to higher dewpoints and less cloud cover expected
overnight. For Wednesday afternoon, scattered cloud cover
expected as daytime heating interacts with low level
moisture, but any local ceilings should remain above MVFR
thresholds.


&&

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

$$

UPDATE...ONTON
SHORT TERM...HJS
LONG TERM...GOETSCH
AVIATION...ONTON







000
FXUS63 KLOT 162342
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
642 PM CDT TUE SEP 16 2014

.DISCUSSION...
254 PM CDT

TONIGHT...
HIGH PRESSURE HAS BECOME CENTERED OVER THE REGION TODAY...PROVIDING
ABUNDANT SUNSHINE AND LIGHT WINDS. THIS EVENING IS SETTING UP TO BE
A BEAUTIFUL ONE WITH MOSTLY CLEAR SKIES AND NEARLY CALM WINDS FOR
MUCH OF THE OVERNIGHT HOURS. TEMPS WILL RADIATE ONCE AGAIN INTO THE
LOW 40S FOR MUCH OF THE FORECAST AREA...WITH THE EXCEPTION BEING
DOWNTOWN CHICAGO WHERE TEMPS WILL LIKELY HOLD IN THE UPR 40S/ARND
50.

WEDNESDAY THROUGH FRIDAY...
MID-LVL TROUGH WILL REMAIN OVERHEAD THRU WED WITH A CONTINUED LIGHT
NORTHWEST FLOW. AT THE SFC BROAD SFC RIDGING WILL REMAIN IN
PLACE...WITH ABUNDANT SUNSHINE ONCE AGAIN WED AFTN. A BACKDOOR FRONT
WILL SLIP SOUTH ACROSS THE LAKE/NORTHERN GREAT LAKES WED EARLY
MORNING...EVENTUALLY ARRIVING ACROSS NORTHERN IL/NORTHWEST IN LATE
WED NGT/EARLY THUR MORNING. THIS WILL LIKELY PRODUCE AN AREA OF
STRATUS AS IT ARRIVES...HOWEVER AT THIS TIME DRY CONDS ARE EXPECTED
TO PERSIST THRU THUR. THEN ANOTHER SFC RIDGE IS POISED TO SLIDE
SOUTH FROM CENTRAL CANADA...AND LINGER OVER THE REGION THRU EARLY
FRI.

AS THE SFC RIDGE FRI BEGINS TO DRIFT EAST...THE MID-LVL FLOW WILL
BEGIN TO FLATTEN. THIS WILL ALLOW A STEADY TURNING IN THE LLVL FLOW
TO THE SOUTH/SOUTHWEST AND BEGIN ADVECTING WARMER/MOIST AIR INTO THE
REGION FRI NGT. GUIDANCE HAS BEEN STEADILY PUSHING POPS BACK UNTIL
FRI NGT...AND COULD SEE THE SFC RIDGE HOLDING INTO FRI NGT WITH POPS
HOLDING OFF UNTIL EARLY SAT.

TEMPS WED/THUR WILL GENERALLY BE IN THE MID/UPR 60S...WITH A FEW
POINTS POSSIBLY TOUCHING 70 MAINLY SOUTH OF I-80. WITH THE BACKDOOR
FRONT SLIPPING SOUTH IT IS POSSIBLE THE CLOUDS COULD LINGER LONG
ENOUGH THUR THAT TEMPS HOLD IN THE LOW 60S TO POSSIBLY UPR 50S
ACROSS THE NORTHERN IL SECTIONS. THEN FOR FRI TEMPS WILL LIKELY
BEGIN TO CLIMB INTO THE LOW TO POSSIBLY MID 70S. OVERNIGHT LOWS WILL
GENERALLY BE IN THE 40S TO LOW 50S.

CONFIDENCE...HIGH.

SATURDAY THROUGH MONDAY...
ENSEMBLES HAVE COME INTO SLIGHTLY BETTER AGREEMENT IN THE SAT/SUN
TIMEFRAME WITH THE 500MB FLOW REMAINING SOMEWHAT FLAT...WHICH SHOULD
HELP TO BRING THE EXPECTED CHANNEL OF MOISTURE/CONVECTION INTO THE
REGION BUT REMAIN PROGRESSIVE. THEN FOR THE SECOND HALF OF THE
WEEKEND ENSEMBLES RETURN THE MID-LVL RIDGE TO THE WESTERN
CONUS...WITH DOWNSTREAM TROUGHING DEVELOPING OVER THE GREAT LAKES
REGION EARLY NEXT WEEK. IT APPEARS THE BEST DAY FOR CONVECTION WILL
END UP BEING SAT NGT/SUN MORNING. TEMPS WILL LIKELY APPROACH 80 DEG
SAT...AND PERHAPS EVEN THE LOW 80S ACROSS THE SOUTHERN CWFA. HOWEVER
THIS WARM-UP APPEARS TO ONLY BE BRIEF WITH TEMPS SUN BACK INTO THE
LOW 70S AND 60S FOR MON.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* LAKE BREEZE EARLY THIS EVENING.
* LAKE BREEZE LATE WEDNESDAY AFTERNOON. CMS

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

THE LAKE BREEZE HAS SURGED INLAND AND IS CURRENTLY MOVING WEST
THROUGH ORD/MDW. SPEEDS MAY REACH 8-10KTS WITH ITS PASSAGE BUT
THEN DIMINISH BACK TO 4-6KTS FOR A FEW HOURS. HIGH PRESSURE OVER
THE REGION TONIGHT WILL ALLOW WINDS TO BECOME LIGHT AND VARIABLE
OR CALM BY LATE EVENING. WINDS WILL THEN BECOME LIGHT SOUTHWEST
OR WEST WEDNESDAY MORNING WITH THE WEAK GRADIENT REMAINING AS THE
CENTER OF THE HIGH SHIFTS EAST. ANOTHER LAKE BREEZE SHOULD
DEVELOP WEDNESDAY AFTERNOON...POSSIBLY REACHING ORD/MDW BY LATE
AFTERNOON. CMS

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

* MEDIUM FOR A LAKE BREEZE REACHING ORD/MDW WEDNESDAY AFTERNOON.
  CMS

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

* THURSDAY AND FRIDAY...DRY/VFR.
* SATURDAY...CHANCE TSRA. GUSTY SOUTHWEST WINDS.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY...DRY/VFR.

&&

.MARINE...
228 PM CDT

HIGH PRESSURE HAS BUILT ACROSS SOUTHERN LAKE MICHIGAN THIS
AFTERNOON. HOWEVER THE SOUTH TO SOUTHWEST GRADIENT HAS INCREASED
ACROSS THE NORTHERN HALF OF THE LAKE AHEAD OF THE NEXT COLD FRONT
OVER LAKE SUPERIOR. THE FRONT WILL SAG SOUTH ACROSS THE
LAKE FOR THE LATTER HALF OF WEDNESDAY INTO WEDNESDAY NIGHT. HIGH
PRESSURE IS RIGHT ON THE HEELS OF THIS FRONT CAUSING A SHARP
INCREASE IN WINDS BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF
THE NORTH-NORTHEAST WEDNESDAY EVENING. EXPECT WINDS WILL BE SLIGHTLY
LESS FARTHER SOUTH AS THE PRESSURE GRADIENT WILL NOT QUITE AS TIGHT
FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL VEER BACK AROUND TO
THE SOUTHEAST THURSDAY AND THURSDAY NIGHT WHILE DIMINISHING...THEN
BECOME SOUTH TO SOUTHWEST FRIDAY INCREASING INTO THE 25 TO 30 KT
RANGE AS BROAD LOW PRESSURE DEVELOPS OVER THE PLAINS AND CANADIAN
PRAIRIES. WINDS MAY STRENGTHEN TO NEAR GALE FORCE SUNDAY AS THE LOW
STRENGTHENS EAST TOWARD LAKE SUPERIOR THEN SHIFTS EAST.

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 162342
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
642 PM CDT TUE SEP 16 2014

.DISCUSSION...
254 PM CDT

TONIGHT...
HIGH PRESSURE HAS BECOME CENTERED OVER THE REGION TODAY...PROVIDING
ABUNDANT SUNSHINE AND LIGHT WINDS. THIS EVENING IS SETTING UP TO BE
A BEAUTIFUL ONE WITH MOSTLY CLEAR SKIES AND NEARLY CALM WINDS FOR
MUCH OF THE OVERNIGHT HOURS. TEMPS WILL RADIATE ONCE AGAIN INTO THE
LOW 40S FOR MUCH OF THE FORECAST AREA...WITH THE EXCEPTION BEING
DOWNTOWN CHICAGO WHERE TEMPS WILL LIKELY HOLD IN THE UPR 40S/ARND
50.

WEDNESDAY THROUGH FRIDAY...
MID-LVL TROUGH WILL REMAIN OVERHEAD THRU WED WITH A CONTINUED LIGHT
NORTHWEST FLOW. AT THE SFC BROAD SFC RIDGING WILL REMAIN IN
PLACE...WITH ABUNDANT SUNSHINE ONCE AGAIN WED AFTN. A BACKDOOR FRONT
WILL SLIP SOUTH ACROSS THE LAKE/NORTHERN GREAT LAKES WED EARLY
MORNING...EVENTUALLY ARRIVING ACROSS NORTHERN IL/NORTHWEST IN LATE
WED NGT/EARLY THUR MORNING. THIS WILL LIKELY PRODUCE AN AREA OF
STRATUS AS IT ARRIVES...HOWEVER AT THIS TIME DRY CONDS ARE EXPECTED
TO PERSIST THRU THUR. THEN ANOTHER SFC RIDGE IS POISED TO SLIDE
SOUTH FROM CENTRAL CANADA...AND LINGER OVER THE REGION THRU EARLY
FRI.

AS THE SFC RIDGE FRI BEGINS TO DRIFT EAST...THE MID-LVL FLOW WILL
BEGIN TO FLATTEN. THIS WILL ALLOW A STEADY TURNING IN THE LLVL FLOW
TO THE SOUTH/SOUTHWEST AND BEGIN ADVECTING WARMER/MOIST AIR INTO THE
REGION FRI NGT. GUIDANCE HAS BEEN STEADILY PUSHING POPS BACK UNTIL
FRI NGT...AND COULD SEE THE SFC RIDGE HOLDING INTO FRI NGT WITH POPS
HOLDING OFF UNTIL EARLY SAT.

TEMPS WED/THUR WILL GENERALLY BE IN THE MID/UPR 60S...WITH A FEW
POINTS POSSIBLY TOUCHING 70 MAINLY SOUTH OF I-80. WITH THE BACKDOOR
FRONT SLIPPING SOUTH IT IS POSSIBLE THE CLOUDS COULD LINGER LONG
ENOUGH THUR THAT TEMPS HOLD IN THE LOW 60S TO POSSIBLY UPR 50S
ACROSS THE NORTHERN IL SECTIONS. THEN FOR FRI TEMPS WILL LIKELY
BEGIN TO CLIMB INTO THE LOW TO POSSIBLY MID 70S. OVERNIGHT LOWS WILL
GENERALLY BE IN THE 40S TO LOW 50S.

CONFIDENCE...HIGH.

SATURDAY THROUGH MONDAY...
ENSEMBLES HAVE COME INTO SLIGHTLY BETTER AGREEMENT IN THE SAT/SUN
TIMEFRAME WITH THE 500MB FLOW REMAINING SOMEWHAT FLAT...WHICH SHOULD
HELP TO BRING THE EXPECTED CHANNEL OF MOISTURE/CONVECTION INTO THE
REGION BUT REMAIN PROGRESSIVE. THEN FOR THE SECOND HALF OF THE
WEEKEND ENSEMBLES RETURN THE MID-LVL RIDGE TO THE WESTERN
CONUS...WITH DOWNSTREAM TROUGHING DEVELOPING OVER THE GREAT LAKES
REGION EARLY NEXT WEEK. IT APPEARS THE BEST DAY FOR CONVECTION WILL
END UP BEING SAT NGT/SUN MORNING. TEMPS WILL LIKELY APPROACH 80 DEG
SAT...AND PERHAPS EVEN THE LOW 80S ACROSS THE SOUTHERN CWFA. HOWEVER
THIS WARM-UP APPEARS TO ONLY BE BRIEF WITH TEMPS SUN BACK INTO THE
LOW 70S AND 60S FOR MON.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* LAKE BREEZE EARLY THIS EVENING.
* LAKE BREEZE LATE WEDNESDAY AFTERNOON. CMS

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

THE LAKE BREEZE HAS SURGED INLAND AND IS CURRENTLY MOVING WEST
THROUGH ORD/MDW. SPEEDS MAY REACH 8-10KTS WITH ITS PASSAGE BUT
THEN DIMINISH BACK TO 4-6KTS FOR A FEW HOURS. HIGH PRESSURE OVER
THE REGION TONIGHT WILL ALLOW WINDS TO BECOME LIGHT AND VARIABLE
OR CALM BY LATE EVENING. WINDS WILL THEN BECOME LIGHT SOUTHWEST
OR WEST WEDNESDAY MORNING WITH THE WEAK GRADIENT REMAINING AS THE
CENTER OF THE HIGH SHIFTS EAST. ANOTHER LAKE BREEZE SHOULD
DEVELOP WEDNESDAY AFTERNOON...POSSIBLY REACHING ORD/MDW BY LATE
AFTERNOON. CMS

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

* MEDIUM FOR A LAKE BREEZE REACHING ORD/MDW WEDNESDAY AFTERNOON.
  CMS

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

* THURSDAY AND FRIDAY...DRY/VFR.
* SATURDAY...CHANCE TSRA. GUSTY SOUTHWEST WINDS.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY...DRY/VFR.

&&

.MARINE...
228 PM CDT

HIGH PRESSURE HAS BUILT ACROSS SOUTHERN LAKE MICHIGAN THIS
AFTERNOON. HOWEVER THE SOUTH TO SOUTHWEST GRADIENT HAS INCREASED
ACROSS THE NORTHERN HALF OF THE LAKE AHEAD OF THE NEXT COLD FRONT
OVER LAKE SUPERIOR. THE FRONT WILL SAG SOUTH ACROSS THE
LAKE FOR THE LATTER HALF OF WEDNESDAY INTO WEDNESDAY NIGHT. HIGH
PRESSURE IS RIGHT ON THE HEELS OF THIS FRONT CAUSING A SHARP
INCREASE IN WINDS BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF
THE NORTH-NORTHEAST WEDNESDAY EVENING. EXPECT WINDS WILL BE SLIGHTLY
LESS FARTHER SOUTH AS THE PRESSURE GRADIENT WILL NOT QUITE AS TIGHT
FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL VEER BACK AROUND TO
THE SOUTHEAST THURSDAY AND THURSDAY NIGHT WHILE DIMINISHING...THEN
BECOME SOUTH TO SOUTHWEST FRIDAY INCREASING INTO THE 25 TO 30 KT
RANGE AS BROAD LOW PRESSURE DEVELOPS OVER THE PLAINS AND CANADIAN
PRAIRIES. WINDS MAY STRENGTHEN TO NEAR GALE FORCE SUNDAY AS THE LOW
STRENGTHENS EAST TOWARD LAKE SUPERIOR THEN SHIFTS EAST.

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 162342
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
642 PM CDT TUE SEP 16 2014

.DISCUSSION...
254 PM CDT

TONIGHT...
HIGH PRESSURE HAS BECOME CENTERED OVER THE REGION TODAY...PROVIDING
ABUNDANT SUNSHINE AND LIGHT WINDS. THIS EVENING IS SETTING UP TO BE
A BEAUTIFUL ONE WITH MOSTLY CLEAR SKIES AND NEARLY CALM WINDS FOR
MUCH OF THE OVERNIGHT HOURS. TEMPS WILL RADIATE ONCE AGAIN INTO THE
LOW 40S FOR MUCH OF THE FORECAST AREA...WITH THE EXCEPTION BEING
DOWNTOWN CHICAGO WHERE TEMPS WILL LIKELY HOLD IN THE UPR 40S/ARND
50.

WEDNESDAY THROUGH FRIDAY...
MID-LVL TROUGH WILL REMAIN OVERHEAD THRU WED WITH A CONTINUED LIGHT
NORTHWEST FLOW. AT THE SFC BROAD SFC RIDGING WILL REMAIN IN
PLACE...WITH ABUNDANT SUNSHINE ONCE AGAIN WED AFTN. A BACKDOOR FRONT
WILL SLIP SOUTH ACROSS THE LAKE/NORTHERN GREAT LAKES WED EARLY
MORNING...EVENTUALLY ARRIVING ACROSS NORTHERN IL/NORTHWEST IN LATE
WED NGT/EARLY THUR MORNING. THIS WILL LIKELY PRODUCE AN AREA OF
STRATUS AS IT ARRIVES...HOWEVER AT THIS TIME DRY CONDS ARE EXPECTED
TO PERSIST THRU THUR. THEN ANOTHER SFC RIDGE IS POISED TO SLIDE
SOUTH FROM CENTRAL CANADA...AND LINGER OVER THE REGION THRU EARLY
FRI.

AS THE SFC RIDGE FRI BEGINS TO DRIFT EAST...THE MID-LVL FLOW WILL
BEGIN TO FLATTEN. THIS WILL ALLOW A STEADY TURNING IN THE LLVL FLOW
TO THE SOUTH/SOUTHWEST AND BEGIN ADVECTING WARMER/MOIST AIR INTO THE
REGION FRI NGT. GUIDANCE HAS BEEN STEADILY PUSHING POPS BACK UNTIL
FRI NGT...AND COULD SEE THE SFC RIDGE HOLDING INTO FRI NGT WITH POPS
HOLDING OFF UNTIL EARLY SAT.

TEMPS WED/THUR WILL GENERALLY BE IN THE MID/UPR 60S...WITH A FEW
POINTS POSSIBLY TOUCHING 70 MAINLY SOUTH OF I-80. WITH THE BACKDOOR
FRONT SLIPPING SOUTH IT IS POSSIBLE THE CLOUDS COULD LINGER LONG
ENOUGH THUR THAT TEMPS HOLD IN THE LOW 60S TO POSSIBLY UPR 50S
ACROSS THE NORTHERN IL SECTIONS. THEN FOR FRI TEMPS WILL LIKELY
BEGIN TO CLIMB INTO THE LOW TO POSSIBLY MID 70S. OVERNIGHT LOWS WILL
GENERALLY BE IN THE 40S TO LOW 50S.

CONFIDENCE...HIGH.

SATURDAY THROUGH MONDAY...
ENSEMBLES HAVE COME INTO SLIGHTLY BETTER AGREEMENT IN THE SAT/SUN
TIMEFRAME WITH THE 500MB FLOW REMAINING SOMEWHAT FLAT...WHICH SHOULD
HELP TO BRING THE EXPECTED CHANNEL OF MOISTURE/CONVECTION INTO THE
REGION BUT REMAIN PROGRESSIVE. THEN FOR THE SECOND HALF OF THE
WEEKEND ENSEMBLES RETURN THE MID-LVL RIDGE TO THE WESTERN
CONUS...WITH DOWNSTREAM TROUGHING DEVELOPING OVER THE GREAT LAKES
REGION EARLY NEXT WEEK. IT APPEARS THE BEST DAY FOR CONVECTION WILL
END UP BEING SAT NGT/SUN MORNING. TEMPS WILL LIKELY APPROACH 80 DEG
SAT...AND PERHAPS EVEN THE LOW 80S ACROSS THE SOUTHERN CWFA. HOWEVER
THIS WARM-UP APPEARS TO ONLY BE BRIEF WITH TEMPS SUN BACK INTO THE
LOW 70S AND 60S FOR MON.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* LAKE BREEZE EARLY THIS EVENING.
* LAKE BREEZE LATE WEDNESDAY AFTERNOON. CMS

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

THE LAKE BREEZE HAS SURGED INLAND AND IS CURRENTLY MOVING WEST
THROUGH ORD/MDW. SPEEDS MAY REACH 8-10KTS WITH ITS PASSAGE BUT
THEN DIMINISH BACK TO 4-6KTS FOR A FEW HOURS. HIGH PRESSURE OVER
THE REGION TONIGHT WILL ALLOW WINDS TO BECOME LIGHT AND VARIABLE
OR CALM BY LATE EVENING. WINDS WILL THEN BECOME LIGHT SOUTHWEST
OR WEST WEDNESDAY MORNING WITH THE WEAK GRADIENT REMAINING AS THE
CENTER OF THE HIGH SHIFTS EAST. ANOTHER LAKE BREEZE SHOULD
DEVELOP WEDNESDAY AFTERNOON...POSSIBLY REACHING ORD/MDW BY LATE
AFTERNOON. CMS

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

* MEDIUM FOR A LAKE BREEZE REACHING ORD/MDW WEDNESDAY AFTERNOON.
  CMS

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

* THURSDAY AND FRIDAY...DRY/VFR.
* SATURDAY...CHANCE TSRA. GUSTY SOUTHWEST WINDS.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY...DRY/VFR.

&&

.MARINE...
228 PM CDT

HIGH PRESSURE HAS BUILT ACROSS SOUTHERN LAKE MICHIGAN THIS
AFTERNOON. HOWEVER THE SOUTH TO SOUTHWEST GRADIENT HAS INCREASED
ACROSS THE NORTHERN HALF OF THE LAKE AHEAD OF THE NEXT COLD FRONT
OVER LAKE SUPERIOR. THE FRONT WILL SAG SOUTH ACROSS THE
LAKE FOR THE LATTER HALF OF WEDNESDAY INTO WEDNESDAY NIGHT. HIGH
PRESSURE IS RIGHT ON THE HEELS OF THIS FRONT CAUSING A SHARP
INCREASE IN WINDS BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF
THE NORTH-NORTHEAST WEDNESDAY EVENING. EXPECT WINDS WILL BE SLIGHTLY
LESS FARTHER SOUTH AS THE PRESSURE GRADIENT WILL NOT QUITE AS TIGHT
FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL VEER BACK AROUND TO
THE SOUTHEAST THURSDAY AND THURSDAY NIGHT WHILE DIMINISHING...THEN
BECOME SOUTH TO SOUTHWEST FRIDAY INCREASING INTO THE 25 TO 30 KT
RANGE AS BROAD LOW PRESSURE DEVELOPS OVER THE PLAINS AND CANADIAN
PRAIRIES. WINDS MAY STRENGTHEN TO NEAR GALE FORCE SUNDAY AS THE LOW
STRENGTHENS EAST TOWARD LAKE SUPERIOR THEN SHIFTS EAST.

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 162342
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
642 PM CDT TUE SEP 16 2014

.DISCUSSION...
254 PM CDT

TONIGHT...
HIGH PRESSURE HAS BECOME CENTERED OVER THE REGION TODAY...PROVIDING
ABUNDANT SUNSHINE AND LIGHT WINDS. THIS EVENING IS SETTING UP TO BE
A BEAUTIFUL ONE WITH MOSTLY CLEAR SKIES AND NEARLY CALM WINDS FOR
MUCH OF THE OVERNIGHT HOURS. TEMPS WILL RADIATE ONCE AGAIN INTO THE
LOW 40S FOR MUCH OF THE FORECAST AREA...WITH THE EXCEPTION BEING
DOWNTOWN CHICAGO WHERE TEMPS WILL LIKELY HOLD IN THE UPR 40S/ARND
50.

WEDNESDAY THROUGH FRIDAY...
MID-LVL TROUGH WILL REMAIN OVERHEAD THRU WED WITH A CONTINUED LIGHT
NORTHWEST FLOW. AT THE SFC BROAD SFC RIDGING WILL REMAIN IN
PLACE...WITH ABUNDANT SUNSHINE ONCE AGAIN WED AFTN. A BACKDOOR FRONT
WILL SLIP SOUTH ACROSS THE LAKE/NORTHERN GREAT LAKES WED EARLY
MORNING...EVENTUALLY ARRIVING ACROSS NORTHERN IL/NORTHWEST IN LATE
WED NGT/EARLY THUR MORNING. THIS WILL LIKELY PRODUCE AN AREA OF
STRATUS AS IT ARRIVES...HOWEVER AT THIS TIME DRY CONDS ARE EXPECTED
TO PERSIST THRU THUR. THEN ANOTHER SFC RIDGE IS POISED TO SLIDE
SOUTH FROM CENTRAL CANADA...AND LINGER OVER THE REGION THRU EARLY
FRI.

AS THE SFC RIDGE FRI BEGINS TO DRIFT EAST...THE MID-LVL FLOW WILL
BEGIN TO FLATTEN. THIS WILL ALLOW A STEADY TURNING IN THE LLVL FLOW
TO THE SOUTH/SOUTHWEST AND BEGIN ADVECTING WARMER/MOIST AIR INTO THE
REGION FRI NGT. GUIDANCE HAS BEEN STEADILY PUSHING POPS BACK UNTIL
FRI NGT...AND COULD SEE THE SFC RIDGE HOLDING INTO FRI NGT WITH POPS
HOLDING OFF UNTIL EARLY SAT.

TEMPS WED/THUR WILL GENERALLY BE IN THE MID/UPR 60S...WITH A FEW
POINTS POSSIBLY TOUCHING 70 MAINLY SOUTH OF I-80. WITH THE BACKDOOR
FRONT SLIPPING SOUTH IT IS POSSIBLE THE CLOUDS COULD LINGER LONG
ENOUGH THUR THAT TEMPS HOLD IN THE LOW 60S TO POSSIBLY UPR 50S
ACROSS THE NORTHERN IL SECTIONS. THEN FOR FRI TEMPS WILL LIKELY
BEGIN TO CLIMB INTO THE LOW TO POSSIBLY MID 70S. OVERNIGHT LOWS WILL
GENERALLY BE IN THE 40S TO LOW 50S.

CONFIDENCE...HIGH.

SATURDAY THROUGH MONDAY...
ENSEMBLES HAVE COME INTO SLIGHTLY BETTER AGREEMENT IN THE SAT/SUN
TIMEFRAME WITH THE 500MB FLOW REMAINING SOMEWHAT FLAT...WHICH SHOULD
HELP TO BRING THE EXPECTED CHANNEL OF MOISTURE/CONVECTION INTO THE
REGION BUT REMAIN PROGRESSIVE. THEN FOR THE SECOND HALF OF THE
WEEKEND ENSEMBLES RETURN THE MID-LVL RIDGE TO THE WESTERN
CONUS...WITH DOWNSTREAM TROUGHING DEVELOPING OVER THE GREAT LAKES
REGION EARLY NEXT WEEK. IT APPEARS THE BEST DAY FOR CONVECTION WILL
END UP BEING SAT NGT/SUN MORNING. TEMPS WILL LIKELY APPROACH 80 DEG
SAT...AND PERHAPS EVEN THE LOW 80S ACROSS THE SOUTHERN CWFA. HOWEVER
THIS WARM-UP APPEARS TO ONLY BE BRIEF WITH TEMPS SUN BACK INTO THE
LOW 70S AND 60S FOR MON.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* LAKE BREEZE EARLY THIS EVENING.
* LAKE BREEZE LATE WEDNESDAY AFTERNOON. CMS

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

THE LAKE BREEZE HAS SURGED INLAND AND IS CURRENTLY MOVING WEST
THROUGH ORD/MDW. SPEEDS MAY REACH 8-10KTS WITH ITS PASSAGE BUT
THEN DIMINISH BACK TO 4-6KTS FOR A FEW HOURS. HIGH PRESSURE OVER
THE REGION TONIGHT WILL ALLOW WINDS TO BECOME LIGHT AND VARIABLE
OR CALM BY LATE EVENING. WINDS WILL THEN BECOME LIGHT SOUTHWEST
OR WEST WEDNESDAY MORNING WITH THE WEAK GRADIENT REMAINING AS THE
CENTER OF THE HIGH SHIFTS EAST. ANOTHER LAKE BREEZE SHOULD
DEVELOP WEDNESDAY AFTERNOON...POSSIBLY REACHING ORD/MDW BY LATE
AFTERNOON. CMS

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

* MEDIUM FOR A LAKE BREEZE REACHING ORD/MDW WEDNESDAY AFTERNOON.
  CMS

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

* THURSDAY AND FRIDAY...DRY/VFR.
* SATURDAY...CHANCE TSRA. GUSTY SOUTHWEST WINDS.
* SUNDAY...SLIGHT CHANCE OF TSRA.
* MONDAY...DRY/VFR.

&&

.MARINE...
228 PM CDT

HIGH PRESSURE HAS BUILT ACROSS SOUTHERN LAKE MICHIGAN THIS
AFTERNOON. HOWEVER THE SOUTH TO SOUTHWEST GRADIENT HAS INCREASED
ACROSS THE NORTHERN HALF OF THE LAKE AHEAD OF THE NEXT COLD FRONT
OVER LAKE SUPERIOR. THE FRONT WILL SAG SOUTH ACROSS THE
LAKE FOR THE LATTER HALF OF WEDNESDAY INTO WEDNESDAY NIGHT. HIGH
PRESSURE IS RIGHT ON THE HEELS OF THIS FRONT CAUSING A SHARP
INCREASE IN WINDS BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF
THE NORTH-NORTHEAST WEDNESDAY EVENING. EXPECT WINDS WILL BE SLIGHTLY
LESS FARTHER SOUTH AS THE PRESSURE GRADIENT WILL NOT QUITE AS TIGHT
FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL VEER BACK AROUND TO
THE SOUTHEAST THURSDAY AND THURSDAY NIGHT WHILE DIMINISHING...THEN
BECOME SOUTH TO SOUTHWEST FRIDAY INCREASING INTO THE 25 TO 30 KT
RANGE AS BROAD LOW PRESSURE DEVELOPS OVER THE PLAINS AND CANADIAN
PRAIRIES. WINDS MAY STRENGTHEN TO NEAR GALE FORCE SUNDAY AS THE LOW
STRENGTHENS EAST TOWARD LAKE SUPERIOR THEN SHIFTS EAST.

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 162313
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
613 PM CDT Tue Sep 16 2014

.SHORT TERM...(Tonight)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure continues to build into the Midwest, and a cold front
is draped across the southern US. Tropical Storm Odile is over the
Gulf of California, parked just south of a 500mb ridge.  Forecast
for ILX is dominated by slow warming trend under the high, and
precip chances into next weekend.  Overnight, expecting quiet
weather and temperatures dropping into the mid-upper 40s. Only
concern will be the potential for fog, particularly in the
southeast, where stratocu have trapped some of the higher dwpts in
the region at the sfc.  Patchy fog in the forecast as a result in
the southeast, further north will still be possible, just not really
enough to mention at this time, provided the dwpts continue to mix
and drop a couple degrees.

&&

.LONG TERM...(Wednesday through Tuesday)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure to move off to the east over the Great Lakes on
Thursday and Friday. Cold front from the northern plains to reach
northern IA by early Saturday. Southerly flow ahead of the front
should bring ample moisture back into the area by the day Saturday.

Models differ some on the movement of the remains of Odile into the
southern plains. Moisture appears to be trending to make it into OK,
but should not reach into IL in time as the front should move in and
advect its remains southward.

The cold front is expected to move into region during the day
Saturday, with the main affects and associated precipitation on
Saturday night for central IL. Exiting precipitation on Sunday, so
gradually dropped pops down through the day.

A new high pressure center would then come in behind the front for
the start of next week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
ISSUED AT 544 PM CDT TUE SEP 16 2014

Surface high pressure meandering across the Midwest will bring
light and variable winds for the next 24 hours. A weak mid-level
shortwave trough crossing Illinois will cause some cloud cover
overnight, but no MVFR ceilings. Fog mention in TAFs continues to
be MVFR from 09Z-12Z, however areas KTAZ-KPRG southward could see
lower values due to higher dewpoints and less cloud cover expected
overnight. For Wednesday afternoon, scattered cloud cover
expected as daytime heating interacts with low level
moisture, but any local ceilings should remain above MVFR
thresholds.

&&

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

$$

SHORT TERM...HJS
LONG TERM...GOETSCH
AVIATION...ONTON






000
FXUS63 KILX 162313
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
613 PM CDT Tue Sep 16 2014

.SHORT TERM...(Tonight)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure continues to build into the Midwest, and a cold front
is draped across the southern US. Tropical Storm Odile is over the
Gulf of California, parked just south of a 500mb ridge.  Forecast
for ILX is dominated by slow warming trend under the high, and
precip chances into next weekend.  Overnight, expecting quiet
weather and temperatures dropping into the mid-upper 40s. Only
concern will be the potential for fog, particularly in the
southeast, where stratocu have trapped some of the higher dwpts in
the region at the sfc.  Patchy fog in the forecast as a result in
the southeast, further north will still be possible, just not really
enough to mention at this time, provided the dwpts continue to mix
and drop a couple degrees.

&&

.LONG TERM...(Wednesday through Tuesday)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure to move off to the east over the Great Lakes on
Thursday and Friday. Cold front from the northern plains to reach
northern IA by early Saturday. Southerly flow ahead of the front
should bring ample moisture back into the area by the day Saturday.

Models differ some on the movement of the remains of Odile into the
southern plains. Moisture appears to be trending to make it into OK,
but should not reach into IL in time as the front should move in and
advect its remains southward.

The cold front is expected to move into region during the day
Saturday, with the main affects and associated precipitation on
Saturday night for central IL. Exiting precipitation on Sunday, so
gradually dropped pops down through the day.

A new high pressure center would then come in behind the front for
the start of next week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
ISSUED AT 544 PM CDT TUE SEP 16 2014

Surface high pressure meandering across the Midwest will bring
light and variable winds for the next 24 hours. A weak mid-level
shortwave trough crossing Illinois will cause some cloud cover
overnight, but no MVFR ceilings. Fog mention in TAFs continues to
be MVFR from 09Z-12Z, however areas KTAZ-KPRG southward could see
lower values due to higher dewpoints and less cloud cover expected
overnight. For Wednesday afternoon, scattered cloud cover
expected as daytime heating interacts with low level
moisture, but any local ceilings should remain above MVFR
thresholds.

&&

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

$$

SHORT TERM...HJS
LONG TERM...GOETSCH
AVIATION...ONTON






000
FXUS63 KILX 162313
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
613 PM CDT Tue Sep 16 2014

.SHORT TERM...(Tonight)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure continues to build into the Midwest, and a cold front
is draped across the southern US. Tropical Storm Odile is over the
Gulf of California, parked just south of a 500mb ridge.  Forecast
for ILX is dominated by slow warming trend under the high, and
precip chances into next weekend.  Overnight, expecting quiet
weather and temperatures dropping into the mid-upper 40s. Only
concern will be the potential for fog, particularly in the
southeast, where stratocu have trapped some of the higher dwpts in
the region at the sfc.  Patchy fog in the forecast as a result in
the southeast, further north will still be possible, just not really
enough to mention at this time, provided the dwpts continue to mix
and drop a couple degrees.

&&

.LONG TERM...(Wednesday through Tuesday)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure to move off to the east over the Great Lakes on
Thursday and Friday. Cold front from the northern plains to reach
northern IA by early Saturday. Southerly flow ahead of the front
should bring ample moisture back into the area by the day Saturday.

Models differ some on the movement of the remains of Odile into the
southern plains. Moisture appears to be trending to make it into OK,
but should not reach into IL in time as the front should move in and
advect its remains southward.

The cold front is expected to move into region during the day
Saturday, with the main affects and associated precipitation on
Saturday night for central IL. Exiting precipitation on Sunday, so
gradually dropped pops down through the day.

A new high pressure center would then come in behind the front for
the start of next week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
ISSUED AT 544 PM CDT TUE SEP 16 2014

Surface high pressure meandering across the Midwest will bring
light and variable winds for the next 24 hours. A weak mid-level
shortwave trough crossing Illinois will cause some cloud cover
overnight, but no MVFR ceilings. Fog mention in TAFs continues to
be MVFR from 09Z-12Z, however areas KTAZ-KPRG southward could see
lower values due to higher dewpoints and less cloud cover expected
overnight. For Wednesday afternoon, scattered cloud cover
expected as daytime heating interacts with low level
moisture, but any local ceilings should remain above MVFR
thresholds.

&&

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

$$

SHORT TERM...HJS
LONG TERM...GOETSCH
AVIATION...ONTON






000
FXUS63 KILX 162313
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
613 PM CDT Tue Sep 16 2014

.SHORT TERM...(Tonight)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure continues to build into the Midwest, and a cold front
is draped across the southern US. Tropical Storm Odile is over the
Gulf of California, parked just south of a 500mb ridge.  Forecast
for ILX is dominated by slow warming trend under the high, and
precip chances into next weekend.  Overnight, expecting quiet
weather and temperatures dropping into the mid-upper 40s. Only
concern will be the potential for fog, particularly in the
southeast, where stratocu have trapped some of the higher dwpts in
the region at the sfc.  Patchy fog in the forecast as a result in
the southeast, further north will still be possible, just not really
enough to mention at this time, provided the dwpts continue to mix
and drop a couple degrees.

&&

.LONG TERM...(Wednesday through Tuesday)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure to move off to the east over the Great Lakes on
Thursday and Friday. Cold front from the northern plains to reach
northern IA by early Saturday. Southerly flow ahead of the front
should bring ample moisture back into the area by the day Saturday.

Models differ some on the movement of the remains of Odile into the
southern plains. Moisture appears to be trending to make it into OK,
but should not reach into IL in time as the front should move in and
advect its remains southward.

The cold front is expected to move into region during the day
Saturday, with the main affects and associated precipitation on
Saturday night for central IL. Exiting precipitation on Sunday, so
gradually dropped pops down through the day.

A new high pressure center would then come in behind the front for
the start of next week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
ISSUED AT 544 PM CDT TUE SEP 16 2014

Surface high pressure meandering across the Midwest will bring
light and variable winds for the next 24 hours. A weak mid-level
shortwave trough crossing Illinois will cause some cloud cover
overnight, but no MVFR ceilings. Fog mention in TAFs continues to
be MVFR from 09Z-12Z, however areas KTAZ-KPRG southward could see
lower values due to higher dewpoints and less cloud cover expected
overnight. For Wednesday afternoon, scattered cloud cover
expected as daytime heating interacts with low level
moisture, but any local ceilings should remain above MVFR
thresholds.

&&

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

$$

SHORT TERM...HJS
LONG TERM...GOETSCH
AVIATION...ONTON






000
FXUS63 KLOT 162201
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
501 PM CDT TUE SEP 16 2014

.DISCUSSION...
254 PM CDT

TONIGHT...
HIGH PRESSURE HAS BECOME CENTERED OVER THE REGION TODAY...PROVIDING
ABUNDANT SUNSHINE AND LIGHT WINDS. THIS EVENING IS SETTING UP TO BE
A BEAUTIFUL ONE WITH MOSTLY CLEAR SKIES AND NEARLY CALM WINDS FOR
MUCH OF THE OVERNIGHT HOURS. TEMPS WILL RADIATE ONCE AGAIN INTO THE
LOW 40S FOR MUCH OF THE FORECAST AREA...WITH THE EXCEPTION BEING
DOWNTOWN CHICAGO WHERE TEMPS WILL LIKELY HOLD IN THE UPR 40S/ARND
50.

WEDNESDAY THROUGH FRIDAY...
MID-LVL TROUGH WILL REMAIN OVERHEAD THRU WED WITH A CONTINUED LIGHT
NORTHWEST FLOW. AT THE SFC BROAD SFC RIDGING WILL REMAIN IN
PLACE...WITH ABUNDANT SUNSHINE ONCE AGAIN WED AFTN. A BACKDOOR FRONT
WILL SLIP SOUTH ACROSS THE LAKE/NORTHERN GREAT LAKES WED EARLY
MORNING...EVENTUALLY ARRIVING ACROSS NORTHERN IL/NORTHWEST IN LATE
WED NGT/EARLY THUR MORNING. THIS WILL LIKELY PRODUCE AN AREA OF
STRATUS AS IT ARRIVES...HOWEVER AT THIS TIME DRY CONDS ARE EXPECTED
TO PERSIST THRU THUR. THEN ANOTHER SFC RIDGE IS POISED TO SLIDE
SOUTH FROM CENTRAL CANADA...AND LINGER OVER THE REGION THRU EARLY
FRI.

AS THE SFC RIDGE FRI BEGINS TO DRIFT EAST...THE MID-LVL FLOW WILL
BEGIN TO FLATTEN. THIS WILL ALLOW A STEADY TURNING IN THE LLVL FLOW
TO THE SOUTH/SOUTHWEST AND BEGIN ADVECTING WARMER/MOIST AIR INTO THE
REGION FRI NGT. GUIDANCE HAS BEEN STEADILY PUSHING POPS BACK UNTIL
FRI NGT...AND COULD SEE THE SFC RIDGE HOLDING INTO FRI NGT WITH POPS
HOLDING OFF UNTIL EARLY SAT.

TEMPS WED/THUR WILL GENERALLY BE IN THE MID/UPR 60S...WITH A FEW
POINTS POSSIBLY TOUCHING 70 MAINLY SOUTH OF I-80. WITH THE BACKDOOR
FRONT SLIPPING SOUTH IT IS POSSIBLE THE CLOUDS COULD LINGER LONG
ENOUGH THUR THAT TEMPS HOLD IN THE LOW 60S TO POSSIBLY UPR 50S
ACROSS THE NORTHERN IL SECTIONS. THEN FOR FRI TEMPS WILL LIKELY
BEGIN TO CLIMB INTO THE LOW TO POSSIBLY MID 70S. OVERNIGHT LOWS WILL
GENERALLY BE IN THE 40S TO LOW 50S.

CONFIDENCE...HIGH.

SATURDAY THROUGH MONDAY...
ENSEMBLES HAVE COME INTO SLIGHTLY BETTER AGREEMENT IN THE SAT/SUN
TIMEFRAME WITH THE 500MB FLOW REMAINING SOMEWHAT FLAT...WHICH SHOULD
HELP TO BRING THE EXPECTED CHANNEL OF MOISTURE/CONVECTION INTO THE
REGION BUT REMAIN PROGRESSIVE. THEN FOR THE SECOND HALF OF THE
WEEKEND ENSEMBLES RETURN THE MID-LVL RIDGE TO THE WESTERN
CONUS...WITH DOWNSTREAM TROUGHING DEVELOPING OVER THE GREAT LAKES
REGION EARLY NEXT WEEK. IT APPEARS THE BEST DAY FOR CONVECTION WILL
END UP BEING SAT NGT/SUN MORNING. TEMPS WILL LIKELY APPROACH 80 DEG
SAT...AND PERHAPS EVEN THE LOW 80S ACROSS THE SOUTHERN CWFA. HOWEVER
THIS WARM-UP APPEARS TO ONLY BE BRIEF WITH TEMPS SUN BACK INTO THE
LOW 70S AND 60S FOR MON.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* POSSIBLE LAKE BREEZE EARLY THIS EVENING. CMS

//DISCUSSION...UPDATED 22Z...

A WEAK LAKE BREEZE IS SLOWLY MOVING INLAND AND WILL LIKELY REACH
MDW BY 00Z AND POSSIBLY ORD BY 01Z. BUT WIND SPEEDS BEHIND THE
LAKE BREEZE ARE EXPECTED TO BE LESS THEN 8 KTS AND THEN SPEEDS
WILL DIMINISH THIS EVENING. CMS

PREVIOUS 18Z DISCUSSION...

AN AREA OF SURFACE HIGH PRESSURE WILL DOMINATE ACROSS THE REGION
THROUGH WEDNESDAY. OVERALL THIS WILL RESULT IN VERY LIGHT
WESTERLY WINDS...MAINLY CLEAR SKIES AND OVERALL NICE WEATHER
THROUGH THE FORECAST PERIOD. AFTERNOON LAKE BREEZES ARE EXPECTED
TODAY AND AGAIN ON WEDNESDAY. HOWEVER...IT APPEARS UNLIKELY THAT
THIS BOUNDARY WILL MAKE IT FAR ENOUGH INLAND TO IMPACT KORD OR
KMDW.

KJB

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

* MEDIUM FOR LAKE BREEZE REACHING ORD/MDW. CMS

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

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.
SATURDAY...THUNDERSTORMS.
SUNDAY THROUGH MONDAY...VFR.

BMD

&&

.MARINE...
228 PM CDT

HIGH PRESSURE HAS BUILT ACROSS SOUTHERN LAKE MICHIGAN THIS
AFTERNOON. HOWEVER THE SOUTH TO SOUTHWEST GRADIENT HAS INCREASED
ACROSS THE NORTHERN HALF OF THE LAKE AHEAD OF THE NEXT COLD FRONT
OVER LAKE SUPERIOR. THE FRONT WILL SAG SOUTH ACROSS THE
LAKE FOR THE LATTER HALF OF WEDNESDAY INTO WEDNESDAY NIGHT. HIGH
PRESSURE IS RIGHT ON THE HEELS OF THIS FRONT CAUSING A SHARP
INCREASE IN WINDS BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF
THE NORTH-NORTHEAST WEDNESDAY EVENING. EXPECT WINDS WILL BE SLIGHTLY
LESS FARTHER SOUTH AS THE PRESSURE GRADIENT WILL NOT QUITE AS TIGHT
FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL VEER BACK AROUND TO
THE SOUTHEAST THURSDAY AND THURSDAY NIGHT WHILE DIMINISHING...THEN
BECOME SOUTH TO SOUTHWEST FRIDAY INCREASING INTO THE 25 TO 30 KT
RANGE AS BROAD LOW PRESSURE DEVELOPS OVER THE PLAINS AND CANADIAN
PRAIRIES. WINDS MAY STRENGTHEN TO NEAR GALE FORCE SUNDAY AS THE LOW
STRENGTHENS EAST TOWARD LAKE SUPERIOR THEN SHIFTS EAST.

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 162201
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
501 PM CDT TUE SEP 16 2014

.DISCUSSION...
254 PM CDT

TONIGHT...
HIGH PRESSURE HAS BECOME CENTERED OVER THE REGION TODAY...PROVIDING
ABUNDANT SUNSHINE AND LIGHT WINDS. THIS EVENING IS SETTING UP TO BE
A BEAUTIFUL ONE WITH MOSTLY CLEAR SKIES AND NEARLY CALM WINDS FOR
MUCH OF THE OVERNIGHT HOURS. TEMPS WILL RADIATE ONCE AGAIN INTO THE
LOW 40S FOR MUCH OF THE FORECAST AREA...WITH THE EXCEPTION BEING
DOWNTOWN CHICAGO WHERE TEMPS WILL LIKELY HOLD IN THE UPR 40S/ARND
50.

WEDNESDAY THROUGH FRIDAY...
MID-LVL TROUGH WILL REMAIN OVERHEAD THRU WED WITH A CONTINUED LIGHT
NORTHWEST FLOW. AT THE SFC BROAD SFC RIDGING WILL REMAIN IN
PLACE...WITH ABUNDANT SUNSHINE ONCE AGAIN WED AFTN. A BACKDOOR FRONT
WILL SLIP SOUTH ACROSS THE LAKE/NORTHERN GREAT LAKES WED EARLY
MORNING...EVENTUALLY ARRIVING ACROSS NORTHERN IL/NORTHWEST IN LATE
WED NGT/EARLY THUR MORNING. THIS WILL LIKELY PRODUCE AN AREA OF
STRATUS AS IT ARRIVES...HOWEVER AT THIS TIME DRY CONDS ARE EXPECTED
TO PERSIST THRU THUR. THEN ANOTHER SFC RIDGE IS POISED TO SLIDE
SOUTH FROM CENTRAL CANADA...AND LINGER OVER THE REGION THRU EARLY
FRI.

AS THE SFC RIDGE FRI BEGINS TO DRIFT EAST...THE MID-LVL FLOW WILL
BEGIN TO FLATTEN. THIS WILL ALLOW A STEADY TURNING IN THE LLVL FLOW
TO THE SOUTH/SOUTHWEST AND BEGIN ADVECTING WARMER/MOIST AIR INTO THE
REGION FRI NGT. GUIDANCE HAS BEEN STEADILY PUSHING POPS BACK UNTIL
FRI NGT...AND COULD SEE THE SFC RIDGE HOLDING INTO FRI NGT WITH POPS
HOLDING OFF UNTIL EARLY SAT.

TEMPS WED/THUR WILL GENERALLY BE IN THE MID/UPR 60S...WITH A FEW
POINTS POSSIBLY TOUCHING 70 MAINLY SOUTH OF I-80. WITH THE BACKDOOR
FRONT SLIPPING SOUTH IT IS POSSIBLE THE CLOUDS COULD LINGER LONG
ENOUGH THUR THAT TEMPS HOLD IN THE LOW 60S TO POSSIBLY UPR 50S
ACROSS THE NORTHERN IL SECTIONS. THEN FOR FRI TEMPS WILL LIKELY
BEGIN TO CLIMB INTO THE LOW TO POSSIBLY MID 70S. OVERNIGHT LOWS WILL
GENERALLY BE IN THE 40S TO LOW 50S.

CONFIDENCE...HIGH.

SATURDAY THROUGH MONDAY...
ENSEMBLES HAVE COME INTO SLIGHTLY BETTER AGREEMENT IN THE SAT/SUN
TIMEFRAME WITH THE 500MB FLOW REMAINING SOMEWHAT FLAT...WHICH SHOULD
HELP TO BRING THE EXPECTED CHANNEL OF MOISTURE/CONVECTION INTO THE
REGION BUT REMAIN PROGRESSIVE. THEN FOR THE SECOND HALF OF THE
WEEKEND ENSEMBLES RETURN THE MID-LVL RIDGE TO THE WESTERN
CONUS...WITH DOWNSTREAM TROUGHING DEVELOPING OVER THE GREAT LAKES
REGION EARLY NEXT WEEK. IT APPEARS THE BEST DAY FOR CONVECTION WILL
END UP BEING SAT NGT/SUN MORNING. TEMPS WILL LIKELY APPROACH 80 DEG
SAT...AND PERHAPS EVEN THE LOW 80S ACROSS THE SOUTHERN CWFA. HOWEVER
THIS WARM-UP APPEARS TO ONLY BE BRIEF WITH TEMPS SUN BACK INTO THE
LOW 70S AND 60S FOR MON.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* POSSIBLE LAKE BREEZE EARLY THIS EVENING. CMS

//DISCUSSION...UPDATED 22Z...

A WEAK LAKE BREEZE IS SLOWLY MOVING INLAND AND WILL LIKELY REACH
MDW BY 00Z AND POSSIBLY ORD BY 01Z. BUT WIND SPEEDS BEHIND THE
LAKE BREEZE ARE EXPECTED TO BE LESS THEN 8 KTS AND THEN SPEEDS
WILL DIMINISH THIS EVENING. CMS

PREVIOUS 18Z DISCUSSION...

AN AREA OF SURFACE HIGH PRESSURE WILL DOMINATE ACROSS THE REGION
THROUGH WEDNESDAY. OVERALL THIS WILL RESULT IN VERY LIGHT
WESTERLY WINDS...MAINLY CLEAR SKIES AND OVERALL NICE WEATHER
THROUGH THE FORECAST PERIOD. AFTERNOON LAKE BREEZES ARE EXPECTED
TODAY AND AGAIN ON WEDNESDAY. HOWEVER...IT APPEARS UNLIKELY THAT
THIS BOUNDARY WILL MAKE IT FAR ENOUGH INLAND TO IMPACT KORD OR
KMDW.

KJB

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

* MEDIUM FOR LAKE BREEZE REACHING ORD/MDW. CMS

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

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.
SATURDAY...THUNDERSTORMS.
SUNDAY THROUGH MONDAY...VFR.

BMD

&&

.MARINE...
228 PM CDT

HIGH PRESSURE HAS BUILT ACROSS SOUTHERN LAKE MICHIGAN THIS
AFTERNOON. HOWEVER THE SOUTH TO SOUTHWEST GRADIENT HAS INCREASED
ACROSS THE NORTHERN HALF OF THE LAKE AHEAD OF THE NEXT COLD FRONT
OVER LAKE SUPERIOR. THE FRONT WILL SAG SOUTH ACROSS THE
LAKE FOR THE LATTER HALF OF WEDNESDAY INTO WEDNESDAY NIGHT. HIGH
PRESSURE IS RIGHT ON THE HEELS OF THIS FRONT CAUSING A SHARP
INCREASE IN WINDS BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF
THE NORTH-NORTHEAST WEDNESDAY EVENING. EXPECT WINDS WILL BE SLIGHTLY
LESS FARTHER SOUTH AS THE PRESSURE GRADIENT WILL NOT QUITE AS TIGHT
FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL VEER BACK AROUND TO
THE SOUTHEAST THURSDAY AND THURSDAY NIGHT WHILE DIMINISHING...THEN
BECOME SOUTH TO SOUTHWEST FRIDAY INCREASING INTO THE 25 TO 30 KT
RANGE AS BROAD LOW PRESSURE DEVELOPS OVER THE PLAINS AND CANADIAN
PRAIRIES. WINDS MAY STRENGTHEN TO NEAR GALE FORCE SUNDAY AS THE LOW
STRENGTHENS EAST TOWARD LAKE SUPERIOR THEN SHIFTS EAST.

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 161957
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
257 PM CDT TUE SEP 16 2014

.DISCUSSION...
254 PM CDT

TONIGHT...
HIGH PRESSURE HAS BECOME CENTERED OVER THE REGION TODAY...PROVIDING
ABUNDANT SUNSHINE AND LIGHT WINDS. THIS EVENING IS SETTING UP TO BE
A BEAUTIFUL ONE WITH MOSTLY CLEAR SKIES AND NEARLY CALM WINDS FOR
MUCH OF THE OVERNIGHT HOURS. TEMPS WILL RADIATE ONCE AGAIN INTO THE
LOW 40S FOR MUCH OF THE FORECAST AREA...WITH THE EXCEPTION BEING
DOWNTOWN CHICAGO WHERE TEMPS WILL LIKELY HOLD IN THE UPR 40S/ARND
50.

WEDNESDAY THROUGH FRIDAY...
MID-LVL TROUGH WILL REMAIN OVERHEAD THRU WED WITH A CONTINUED LIGHT
NORTHWEST FLOW. AT THE SFC BROAD SFC RIDGING WILL REMAIN IN
PLACE...WITH ABUNDANT SUNSHINE ONCE AGAIN WED AFTN. A BACKDOOR FRONT
WILL SLIP SOUTH ACROSS THE LAKE/NORTHERN GREAT LAKES WED EARLY
MORNING...EVENTUALLY ARRIVING ACROSS NORTHERN IL/NORTHWEST IN LATE
WED NGT/EARLY THUR MORNING. THIS WILL LIKELY PRODUCE AN AREA OF
STRATUS AS IT ARRIVES...HOWEVER AT THIS TIME DRY CONDS ARE EXPECTED
TO PERSIST THRU THUR. THEN ANOTHER SFC RIDGE IS POISED TO SLIDE
SOUTH FROM CENTRAL CANADA...AND LINGER OVER THE REGION THRU EARLY
FRI.

AS THE SFC RIDGE FRI BEGINS TO DRIFT EAST...THE MID-LVL FLOW WILL
BEGIN TO FLATTEN. THIS WILL ALLOW A STEADY TURNING IN THE LLVL FLOW
TO THE SOUTH/SOUTHWEST AND BEGIN ADVECTING WARMER/MOIST AIR INTO THE
REGION FRI NGT. GUIDANCE HAS BEEN STEADILY PUSHING POPS BACK UNTIL
FRI NGT...AND COULD SEE THE SFC RIDGE HOLDING INTO FRI NGT WITH POPS
HOLDING OFF UNTIL EARLY SAT.

TEMPS WED/THUR WILL GENERALLY BE IN THE MID/UPR 60S...WITH A FEW
POINTS POSSIBLY TOUCHING 70 MAINLY SOUTH OF I-80. WITH THE BACKDOOR
FRONT SLIPPING SOUTH IT IS POSSIBLE THE CLOUDS COULD LINGER LONG
ENOUGH THUR THAT TEMPS HOLD IN THE LOW 60S TO POSSIBLY UPR 50S
ACROSS THE NORTHERN IL SECTIONS. THEN FOR FRI TEMPS WILL LIKELY
BEGIN TO CLIMB INTO THE LOW TO POSSIBLY MID 70S. OVERNIGHT LOWS WILL
GENERALLY BE IN THE 40S TO LOW 50S.

CONFIDENCE...HIGH.

SATURDAY THROUGH MONDAY...
ENSEMBLES HAVE COME INTO SLIGHTLY BETTER AGREEMENT IN THE SAT/SUN
TIMEFRAME WITH THE 500MB FLOW REMAINING SOMEWHAT FLAT...WHICH SHOULD
HELP TO BRING THE EXPECTED CHANNEL OF MOISTURE/CONVECTION INTO THE
REGION BUT REMAIN PROGRESSIVE. THEN FOR THE SECOND HALF OF THE
WEEKEND ENSEMBLES RETURN THE MID-LVL RIDGE TO THE WESTERN
CONUS...WITH DOWNSTREAM TROUGHING DEVELOPING OVER THE GREAT LAKES
REGION EARLY NEXT WEEK. IT APPEARS THE BEST DAY FOR CONVECTION WILL
END UP BEING SAT NGT/SUN MORNING. TEMPS WILL LIKELY APPROACH 80 DEG
SAT...AND PERHAPS EVEN THE LOW 80S ACROSS THE SOUTHERN CWFA. HOWEVER
THIS WARM-UP APPEARS TO ONLY BE BRIEF WITH TEMPS SUN BACK INTO THE
LOW 70S AND 60S FOR MON.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* LAKE BREEZE MAY IMPACT KMDW AFTER 22 UTC WITH A VRB OR EAST-
  NORTHEAST WIND DIRECTION. SPEEDS SHOULD BE UNDER 7 KT.

KJB

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

AN AREA OF SURFACE HIGH PRESSURE WILL DOMINATE ACROSS THE REGION
THROUGH WEDNESDAY. OVERALL THIS WILL RESULT IN VERY LIGHT
WESTERLY WINDS...MAINLY CLEAR SKIES AND OVERALL NICE WEATHER
THROUGH THE FORECAST PERIOD. AFTERNOON LAKE BREEZES ARE EXPECTED
TODAY AND AGAIN ON WEDNESDAY. HOWEVER...IT APPEARS UNLIKELY THAT
THIS BOUNDARY WILL MAKE IT FAR ENOUGH INLAND TO IMPACT KORD OR
KMDW.

KJB

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

* LOW-MEDIUM FOR LAKE BREEZE MAKING IT TO KMDW AFTER 22 UTC.

* HIGH FOR ALL OTHER ELEMENTS.

KJB

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

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.
SATURDAY...THUNDERSTORMS.
SUNDAY THROUGH MONDAY...VFR.

BMD

&&

.MARINE...
228 PM CDT

HIGH PRESSURE HAS BUILT ACROSS SOUTHERN LAKE MICHIGAN THIS
AFTERNOON. HOWEVER THE SOUTH TO SOUTHWEST GRADIENT HAS INCREASED
ACROSS THE NORTHERN HALF OF THE LAKE AHEAD OF THE NEXT COLD FRONT
OVER LAKE SUPERIOR. THE FRONT WILL SAG SOUTH ACROSS THE
LAKE FOR THE LATTER HALF OF WEDNESDAY INTO WEDNESDAY NIGHT. HIGH
PRESSURE IS RIGHT ON THE HEELS OF THIS FRONT CAUSING A SHARP
INCREASE IN WINDS BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF
THE NORTH-NORTHEAST WEDNESDAY EVENING. EXPECT WINDS WILL BE SLIGHTLY
LESS FARTHER SOUTH AS THE PRESSURE GRADIENT WILL NOT QUITE AS TIGHT
FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL VEER BACK AROUND TO
THE SOUTHEAST THURSDAY AND THURSDAY NIGHT WHILE DIMINISHING...THEN
BECOME SOUTH TO SOUTHWEST FRIDAY INCREASING INTO THE 25 TO 30 KT
RANGE AS BROAD LOW PRESSURE DEVELOPS OVER THE PLAINS AND CANADIAN
PRAIRIES. WINDS MAY STRENGTHEN TO NEAR GALE FORCE SUNDAY AS THE LOW
STRENGTHENS EAST TOWARD LAKE SUPERIOR THEN SHIFTS EAST.

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 161957
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
257 PM CDT TUE SEP 16 2014

.DISCUSSION...
254 PM CDT

TONIGHT...
HIGH PRESSURE HAS BECOME CENTERED OVER THE REGION TODAY...PROVIDING
ABUNDANT SUNSHINE AND LIGHT WINDS. THIS EVENING IS SETTING UP TO BE
A BEAUTIFUL ONE WITH MOSTLY CLEAR SKIES AND NEARLY CALM WINDS FOR
MUCH OF THE OVERNIGHT HOURS. TEMPS WILL RADIATE ONCE AGAIN INTO THE
LOW 40S FOR MUCH OF THE FORECAST AREA...WITH THE EXCEPTION BEING
DOWNTOWN CHICAGO WHERE TEMPS WILL LIKELY HOLD IN THE UPR 40S/ARND
50.

WEDNESDAY THROUGH FRIDAY...
MID-LVL TROUGH WILL REMAIN OVERHEAD THRU WED WITH A CONTINUED LIGHT
NORTHWEST FLOW. AT THE SFC BROAD SFC RIDGING WILL REMAIN IN
PLACE...WITH ABUNDANT SUNSHINE ONCE AGAIN WED AFTN. A BACKDOOR FRONT
WILL SLIP SOUTH ACROSS THE LAKE/NORTHERN GREAT LAKES WED EARLY
MORNING...EVENTUALLY ARRIVING ACROSS NORTHERN IL/NORTHWEST IN LATE
WED NGT/EARLY THUR MORNING. THIS WILL LIKELY PRODUCE AN AREA OF
STRATUS AS IT ARRIVES...HOWEVER AT THIS TIME DRY CONDS ARE EXPECTED
TO PERSIST THRU THUR. THEN ANOTHER SFC RIDGE IS POISED TO SLIDE
SOUTH FROM CENTRAL CANADA...AND LINGER OVER THE REGION THRU EARLY
FRI.

AS THE SFC RIDGE FRI BEGINS TO DRIFT EAST...THE MID-LVL FLOW WILL
BEGIN TO FLATTEN. THIS WILL ALLOW A STEADY TURNING IN THE LLVL FLOW
TO THE SOUTH/SOUTHWEST AND BEGIN ADVECTING WARMER/MOIST AIR INTO THE
REGION FRI NGT. GUIDANCE HAS BEEN STEADILY PUSHING POPS BACK UNTIL
FRI NGT...AND COULD SEE THE SFC RIDGE HOLDING INTO FRI NGT WITH POPS
HOLDING OFF UNTIL EARLY SAT.

TEMPS WED/THUR WILL GENERALLY BE IN THE MID/UPR 60S...WITH A FEW
POINTS POSSIBLY TOUCHING 70 MAINLY SOUTH OF I-80. WITH THE BACKDOOR
FRONT SLIPPING SOUTH IT IS POSSIBLE THE CLOUDS COULD LINGER LONG
ENOUGH THUR THAT TEMPS HOLD IN THE LOW 60S TO POSSIBLY UPR 50S
ACROSS THE NORTHERN IL SECTIONS. THEN FOR FRI TEMPS WILL LIKELY
BEGIN TO CLIMB INTO THE LOW TO POSSIBLY MID 70S. OVERNIGHT LOWS WILL
GENERALLY BE IN THE 40S TO LOW 50S.

CONFIDENCE...HIGH.

SATURDAY THROUGH MONDAY...
ENSEMBLES HAVE COME INTO SLIGHTLY BETTER AGREEMENT IN THE SAT/SUN
TIMEFRAME WITH THE 500MB FLOW REMAINING SOMEWHAT FLAT...WHICH SHOULD
HELP TO BRING THE EXPECTED CHANNEL OF MOISTURE/CONVECTION INTO THE
REGION BUT REMAIN PROGRESSIVE. THEN FOR THE SECOND HALF OF THE
WEEKEND ENSEMBLES RETURN THE MID-LVL RIDGE TO THE WESTERN
CONUS...WITH DOWNSTREAM TROUGHING DEVELOPING OVER THE GREAT LAKES
REGION EARLY NEXT WEEK. IT APPEARS THE BEST DAY FOR CONVECTION WILL
END UP BEING SAT NGT/SUN MORNING. TEMPS WILL LIKELY APPROACH 80 DEG
SAT...AND PERHAPS EVEN THE LOW 80S ACROSS THE SOUTHERN CWFA. HOWEVER
THIS WARM-UP APPEARS TO ONLY BE BRIEF WITH TEMPS SUN BACK INTO THE
LOW 70S AND 60S FOR MON.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* LAKE BREEZE MAY IMPACT KMDW AFTER 22 UTC WITH A VRB OR EAST-
  NORTHEAST WIND DIRECTION. SPEEDS SHOULD BE UNDER 7 KT.

KJB

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

AN AREA OF SURFACE HIGH PRESSURE WILL DOMINATE ACROSS THE REGION
THROUGH WEDNESDAY. OVERALL THIS WILL RESULT IN VERY LIGHT
WESTERLY WINDS...MAINLY CLEAR SKIES AND OVERALL NICE WEATHER
THROUGH THE FORECAST PERIOD. AFTERNOON LAKE BREEZES ARE EXPECTED
TODAY AND AGAIN ON WEDNESDAY. HOWEVER...IT APPEARS UNLIKELY THAT
THIS BOUNDARY WILL MAKE IT FAR ENOUGH INLAND TO IMPACT KORD OR
KMDW.

KJB

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

* LOW-MEDIUM FOR LAKE BREEZE MAKING IT TO KMDW AFTER 22 UTC.

* HIGH FOR ALL OTHER ELEMENTS.

KJB

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

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.
SATURDAY...THUNDERSTORMS.
SUNDAY THROUGH MONDAY...VFR.

BMD

&&

.MARINE...
228 PM CDT

HIGH PRESSURE HAS BUILT ACROSS SOUTHERN LAKE MICHIGAN THIS
AFTERNOON. HOWEVER THE SOUTH TO SOUTHWEST GRADIENT HAS INCREASED
ACROSS THE NORTHERN HALF OF THE LAKE AHEAD OF THE NEXT COLD FRONT
OVER LAKE SUPERIOR. THE FRONT WILL SAG SOUTH ACROSS THE
LAKE FOR THE LATTER HALF OF WEDNESDAY INTO WEDNESDAY NIGHT. HIGH
PRESSURE IS RIGHT ON THE HEELS OF THIS FRONT CAUSING A SHARP
INCREASE IN WINDS BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF
THE NORTH-NORTHEAST WEDNESDAY EVENING. EXPECT WINDS WILL BE SLIGHTLY
LESS FARTHER SOUTH AS THE PRESSURE GRADIENT WILL NOT QUITE AS TIGHT
FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL VEER BACK AROUND TO
THE SOUTHEAST THURSDAY AND THURSDAY NIGHT WHILE DIMINISHING...THEN
BECOME SOUTH TO SOUTHWEST FRIDAY INCREASING INTO THE 25 TO 30 KT
RANGE AS BROAD LOW PRESSURE DEVELOPS OVER THE PLAINS AND CANADIAN
PRAIRIES. WINDS MAY STRENGTHEN TO NEAR GALE FORCE SUNDAY AS THE LOW
STRENGTHENS EAST TOWARD LAKE SUPERIOR THEN SHIFTS EAST.

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 161954
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
254 PM CDT TUE SEP 16 2014

.DISCUSSION...
254 PM CDT

TONIGHT...
HIGH PRESSURE HAS BECOME CENTERED OVER THE REGION TODAY...PROVIDING
ABUNDANT SUNSHINE AND LIGHT WINDS. THIS EVENING IS SETTING UP TO BE
A BEAUTIFUL ONE WITH MOSTLY CLEAR SKIES AND NEARLY CALM WINDS FOR
MUCH OF THE OVERNIGHT HOURS. TEMPS WILL RADIATE ONCE AGAIN INTO THE
LOW 40S FOR MUCH OF THE FORECAST AREA...WITH THE EXCEPTION BEING
DOWNTOWN CHICAGO WHERE TEMPS WILL LIKELY HOLD IN THE UPR 40S/ARND
50.

WEDNESDAY THROUGH FRIDAY...
MID-LVL TROUGH WILL REMAIN OVERHEAD THRU WED WITH A CONTINUED LIGHT
NORTHWEST FLOW. AT THE SFC BROAD SFC RIDGING WILL REMAIN IN
PLACE...WITH ABUNDANT SUNSHINE ONCE AGAIN WED AFTN. A BACKDOOR FRONT
WILL SLIP SOUTH ACROSS THE LAKE/NORTHERN GREAT LAKES WED EARLY
MORNING...EVENTUALLY ARRIVING ACROSS NORTHERN IL/NORTHWEST IN LATE
WED NGT/EARLY THUR MORNING. THIS WILL LIKELY PRODUCE AN AREA OF
STRATUS AS IT ARRIVES...HOWEVER AT THIS TIME DRY CONDS ARE EXPECTED
TO PERSIST THRU THUR. THEN ANOTHER SFC RIDGE IS POISED TO SLIDE
SOUTH FROM CENTRAL CANADA...AND LINGER OVER THE REGION THRU EARLY
FRI.

AS THE SFC RIDGE FRI BEGINS TO DRIFT EAST...THE MID-LVL FLOW WILL
BEGIN TO FLATTEN. THIS WILL ALLOW A STEADY TURNING IN THE LLVL FLOW
TO THE SOUTH/SOUTHWEST AND BEGIN ADVECTING WARMER/MOIST AIR INTO THE
REGION FRI NGT. GUIDANCE HAS BEEN STEADILY PUSHING POPS BACK UNTIL
FRI NGT...AND COULD SEE THE SFC RIDGE HOLDING INTO FRI NGT WITH POPS
HOLDING OFF UNTIL EARLY SAT.

TEMPS WED/THUR WILL GENERALLY BE IN THE MID/UPR 60S...WITH A FEW
POINTS POSSIBLY TOUCHING 70 MAINLY SOUTH OF I-80. WITH THE BACKDOOR
FRONT SLIPPING SOUTH IT IS POSSIBLE THE CLOUDS COULD LINGER LONG
ENOUGH THUR THAT TEMPS HOLD IN THE LOW 60S TO POSSIBLY UPR 50S
ACROSS THE NORTHERN IL SECTIONS. THEN FOR FRI TEMPS WILL LIKELY
BEGIN TO CLIMB INTO THE LOW TO POSSIBLY MID 70S. OVERNIGHT LOWS WILL
GENERALLY BE IN THE 40S TO LOW 50S.

CONFIDENCE...HIGH.

SATURDAY THROUGH MONDAY...
ENSEMBLES HAVE COME INTO SLIGHTLY BETTER AGREEMENT IN THE SAT/SUN
TIMEFRAME WITH THE 500MB FLOW REMAINING SOMEWHAT FLAT...WHICH SHOULD
HELP TO BRING THE EXPECTED CHANNEL OF MOISTURE/CONVECTION INTO THE
REGION BUT REMAIN PROGRESSIVE. THEN FOR THE SECOND HALF OF THE
WEEKEND ENSEMBLES RETURN THE MID-LVL RIDGE TO THE WESTERN
CONUS...WITH DOWNSTREAM TROUGHING DEVELOPING OVER THE GREAT LAKES
REGION EARLY NEXT WEEK. IT APPEARS THE BEST DAY FOR CONVECTION WILL
END UP BEING SAT NGT/SUN MORNING. TEMPS WILL LIKELY APPROACH 80 DEG
SAT...AND PERHAPS EVEN THE LOW 80S ACROSS THE SOUTHERN CWFA. HOWEVER
THIS WARM-UP APPEARS TO ONLY BE BRIEF WITH TEMPS SUN BACK INTO THE
LOW 70S AND 60S FOR MON.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* NONE.

KJB

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

AN AREA OF SURFACE HIGH PRESSURE WILL DOMINATE ACROSS THE REGION
THROUGH WEDNESDAY. OVERALL THIS WILL RESULT IN VERY LIGHT
WESTERLY WINDS...MAINLY CLEAR SKIES AND OVERALL NICE WEATHER
THROUGH THE FORECAST PERIOD. AFTERNOON LAKE BREEZES ARE EXPECTED
TODAY AND AGAIN ON WEDNESDAY. HOWEVER...IT APPEARS UNLIKELY THAT
THIS BOUNDARY WILL MAKE IT FAR ENOUGH INLAND TO IMPACT KORD OR
KMDW.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* HIGH FOR ALL ELEMENTS.

KJB

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

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.
SATURDAY...THUNDERSTORMS.
SUNDAY THROUGH MONDAY...VFR.

BMD

&&

.MARINE...
228 PM CDT

HIGH PRESSURE HAS BUILT ACROSS SOUTHERN LAKE MICHIGAN THIS
AFTERNOON. HOWEVER THE SOUTH TO SOUTHWEST GRADIENT HAS INCREASED
ACROSS THE NORTHERN HALF OF THE LAKE AHEAD OF THE NEXT COLD FRONT
OVER LAKE SUPERIOR. THE FRONT WILL SAG SOUTH ACROSS THE
LAKE FOR THE LATTER HALF OF WEDNESDAY INTO WEDNESDAY NIGHT. HIGH
PRESSURE IS RIGHT ON THE HEELS OF THIS FRONT CAUSING A SHARP
INCREASE IN WINDS BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF
THE NORTH-NORTHEAST WEDNESDAY EVENING. EXPECT WINDS WILL BE SLIGHTLY
LESS FARTHER SOUTH AS THE PRESSURE GRADIENT WILL NOT QUITE AS TIGHT
FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL VEER BACK AROUND TO
THE SOUTHEAST THURSDAY AND THURSDAY NIGHT WHILE DIMINISHING...THEN
BECOME SOUTH TO SOUTHWEST FRIDAY INCREASING INTO THE 25 TO 30 KT
RANGE AS BROAD LOW PRESSURE DEVELOPS OVER THE PLAINS AND CANADIAN
PRAIRIES. WINDS MAY STRENGTHEN TO NEAR GALE FORCE SUNDAY AS THE LOW
STRENGTHENS EAST TOWARD LAKE SUPERIOR THEN SHIFTS EAST.

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 KLOT 161954
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
254 PM CDT TUE SEP 16 2014

.DISCUSSION...
254 PM CDT

TONIGHT...
HIGH PRESSURE HAS BECOME CENTERED OVER THE REGION TODAY...PROVIDING
ABUNDANT SUNSHINE AND LIGHT WINDS. THIS EVENING IS SETTING UP TO BE
A BEAUTIFUL ONE WITH MOSTLY CLEAR SKIES AND NEARLY CALM WINDS FOR
MUCH OF THE OVERNIGHT HOURS. TEMPS WILL RADIATE ONCE AGAIN INTO THE
LOW 40S FOR MUCH OF THE FORECAST AREA...WITH THE EXCEPTION BEING
DOWNTOWN CHICAGO WHERE TEMPS WILL LIKELY HOLD IN THE UPR 40S/ARND
50.

WEDNESDAY THROUGH FRIDAY...
MID-LVL TROUGH WILL REMAIN OVERHEAD THRU WED WITH A CONTINUED LIGHT
NORTHWEST FLOW. AT THE SFC BROAD SFC RIDGING WILL REMAIN IN
PLACE...WITH ABUNDANT SUNSHINE ONCE AGAIN WED AFTN. A BACKDOOR FRONT
WILL SLIP SOUTH ACROSS THE LAKE/NORTHERN GREAT LAKES WED EARLY
MORNING...EVENTUALLY ARRIVING ACROSS NORTHERN IL/NORTHWEST IN LATE
WED NGT/EARLY THUR MORNING. THIS WILL LIKELY PRODUCE AN AREA OF
STRATUS AS IT ARRIVES...HOWEVER AT THIS TIME DRY CONDS ARE EXPECTED
TO PERSIST THRU THUR. THEN ANOTHER SFC RIDGE IS POISED TO SLIDE
SOUTH FROM CENTRAL CANADA...AND LINGER OVER THE REGION THRU EARLY
FRI.

AS THE SFC RIDGE FRI BEGINS TO DRIFT EAST...THE MID-LVL FLOW WILL
BEGIN TO FLATTEN. THIS WILL ALLOW A STEADY TURNING IN THE LLVL FLOW
TO THE SOUTH/SOUTHWEST AND BEGIN ADVECTING WARMER/MOIST AIR INTO THE
REGION FRI NGT. GUIDANCE HAS BEEN STEADILY PUSHING POPS BACK UNTIL
FRI NGT...AND COULD SEE THE SFC RIDGE HOLDING INTO FRI NGT WITH POPS
HOLDING OFF UNTIL EARLY SAT.

TEMPS WED/THUR WILL GENERALLY BE IN THE MID/UPR 60S...WITH A FEW
POINTS POSSIBLY TOUCHING 70 MAINLY SOUTH OF I-80. WITH THE BACKDOOR
FRONT SLIPPING SOUTH IT IS POSSIBLE THE CLOUDS COULD LINGER LONG
ENOUGH THUR THAT TEMPS HOLD IN THE LOW 60S TO POSSIBLY UPR 50S
ACROSS THE NORTHERN IL SECTIONS. THEN FOR FRI TEMPS WILL LIKELY
BEGIN TO CLIMB INTO THE LOW TO POSSIBLY MID 70S. OVERNIGHT LOWS WILL
GENERALLY BE IN THE 40S TO LOW 50S.

CONFIDENCE...HIGH.

SATURDAY THROUGH MONDAY...
ENSEMBLES HAVE COME INTO SLIGHTLY BETTER AGREEMENT IN THE SAT/SUN
TIMEFRAME WITH THE 500MB FLOW REMAINING SOMEWHAT FLAT...WHICH SHOULD
HELP TO BRING THE EXPECTED CHANNEL OF MOISTURE/CONVECTION INTO THE
REGION BUT REMAIN PROGRESSIVE. THEN FOR THE SECOND HALF OF THE
WEEKEND ENSEMBLES RETURN THE MID-LVL RIDGE TO THE WESTERN
CONUS...WITH DOWNSTREAM TROUGHING DEVELOPING OVER THE GREAT LAKES
REGION EARLY NEXT WEEK. IT APPEARS THE BEST DAY FOR CONVECTION WILL
END UP BEING SAT NGT/SUN MORNING. TEMPS WILL LIKELY APPROACH 80 DEG
SAT...AND PERHAPS EVEN THE LOW 80S ACROSS THE SOUTHERN CWFA. HOWEVER
THIS WARM-UP APPEARS TO ONLY BE BRIEF WITH TEMPS SUN BACK INTO THE
LOW 70S AND 60S FOR MON.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* NONE.

KJB

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

AN AREA OF SURFACE HIGH PRESSURE WILL DOMINATE ACROSS THE REGION
THROUGH WEDNESDAY. OVERALL THIS WILL RESULT IN VERY LIGHT
WESTERLY WINDS...MAINLY CLEAR SKIES AND OVERALL NICE WEATHER
THROUGH THE FORECAST PERIOD. AFTERNOON LAKE BREEZES ARE EXPECTED
TODAY AND AGAIN ON WEDNESDAY. HOWEVER...IT APPEARS UNLIKELY THAT
THIS BOUNDARY WILL MAKE IT FAR ENOUGH INLAND TO IMPACT KORD OR
KMDW.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* HIGH FOR ALL ELEMENTS.

KJB

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

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.
SATURDAY...THUNDERSTORMS.
SUNDAY THROUGH MONDAY...VFR.

BMD

&&

.MARINE...
228 PM CDT

HIGH PRESSURE HAS BUILT ACROSS SOUTHERN LAKE MICHIGAN THIS
AFTERNOON. HOWEVER THE SOUTH TO SOUTHWEST GRADIENT HAS INCREASED
ACROSS THE NORTHERN HALF OF THE LAKE AHEAD OF THE NEXT COLD FRONT
OVER LAKE SUPERIOR. THE FRONT WILL SAG SOUTH ACROSS THE
LAKE FOR THE LATTER HALF OF WEDNESDAY INTO WEDNESDAY NIGHT. HIGH
PRESSURE IS RIGHT ON THE HEELS OF THIS FRONT CAUSING A SHARP
INCREASE IN WINDS BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF
THE NORTH-NORTHEAST WEDNESDAY EVENING. EXPECT WINDS WILL BE SLIGHTLY
LESS FARTHER SOUTH AS THE PRESSURE GRADIENT WILL NOT QUITE AS TIGHT
FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL VEER BACK AROUND TO
THE SOUTHEAST THURSDAY AND THURSDAY NIGHT WHILE DIMINISHING...THEN
BECOME SOUTH TO SOUTHWEST FRIDAY INCREASING INTO THE 25 TO 30 KT
RANGE AS BROAD LOW PRESSURE DEVELOPS OVER THE PLAINS AND CANADIAN
PRAIRIES. WINDS MAY STRENGTHEN TO NEAR GALE FORCE SUNDAY AS THE LOW
STRENGTHENS EAST TOWARD LAKE SUPERIOR THEN SHIFTS EAST.

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 161948
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
248 PM CDT Tue Sep 16 2014

.SHORT TERM...(Tonight)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure continues to build into the Midwest, and a cold front
is draped across the southern US. Tropical Storm Odile is over the
Gulf of California, parked just south of a 500mb ridge.  Forecast
for ILX is dominated by slow warming trend under the high, and
precip chances into next weekend.  Overnight, expecting quiet
weather and temperatures dropping into the mid-upper 40s. Only
concern will be the potential for fog, particularly in the
southeast, where stratocu have trapped some of the higher dwpts in
the region at the sfc.  Patchy fog in the forecast as a result in
the southeast, further north will still be possible, just not really
enough to mention at this time, provided the dwpts continue to mix
and drop a couple degrees.


&&

.LONG TERM...(Wednesday through Tuesday)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure to move off to the east over the Great Lakes on
Thursday and Friday. Cold front from the northern plains to reach
northern IA by early Saturday. Southerly flow ahead of the front
should bring ample moisture back into the area by the day Saturday.

Models differ some on the movement of the remains of Odile into the
southern plains. Moisture appears to be trending to make it into OK,
but should not reach into IL in time as the front should move in and
advect its remains southward.

The cold front is expected to move into region during the day
Saturday, with the main affects and associated precipitation on
Saturday night for central IL. Exiting precipitation on Sunday, so
gradually dropped pops down through the day.

A new high pressure center would then come in behind the front for
the start of next week.


&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
ISSUED AT 1222 PM CDT TUE SEP 16 2014
Light and variable winds throughout the pd under a building sfc
ridge. Main issue becomes the retreat of the stratus in the srn
terminals...OVC in DEC and BKN in both CMI and SPI, hanging close
to the MVFR/VFR break. Per vis sat imagery, the stratus erodes and
is replaced by a blooming cu field almost immediately. Given this
trend...am leaving current conditions until about an hour or two
before sunset as the cu field breaks up. For now, fog mention is
still MVFR, though the lingering llvl moisture in the south will
lend itself to lower vis in the srn terminals should it not be
able to mix out by max heating this afternoon.


&&

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

$$

SHORT TERM...HJS
LONG TERM...GOETSCH
AVIATION...HJS






000
FXUS63 KILX 161948
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
248 PM CDT Tue Sep 16 2014

.SHORT TERM...(Tonight)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure continues to build into the Midwest, and a cold front
is draped across the southern US. Tropical Storm Odile is over the
Gulf of California, parked just south of a 500mb ridge.  Forecast
for ILX is dominated by slow warming trend under the high, and
precip chances into next weekend.  Overnight, expecting quiet
weather and temperatures dropping into the mid-upper 40s. Only
concern will be the potential for fog, particularly in the
southeast, where stratocu have trapped some of the higher dwpts in
the region at the sfc.  Patchy fog in the forecast as a result in
the southeast, further north will still be possible, just not really
enough to mention at this time, provided the dwpts continue to mix
and drop a couple degrees.


&&

.LONG TERM...(Wednesday through Tuesday)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure to move off to the east over the Great Lakes on
Thursday and Friday. Cold front from the northern plains to reach
northern IA by early Saturday. Southerly flow ahead of the front
should bring ample moisture back into the area by the day Saturday.

Models differ some on the movement of the remains of Odile into the
southern plains. Moisture appears to be trending to make it into OK,
but should not reach into IL in time as the front should move in and
advect its remains southward.

The cold front is expected to move into region during the day
Saturday, with the main affects and associated precipitation on
Saturday night for central IL. Exiting precipitation on Sunday, so
gradually dropped pops down through the day.

A new high pressure center would then come in behind the front for
the start of next week.


&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
ISSUED AT 1222 PM CDT TUE SEP 16 2014
Light and variable winds throughout the pd under a building sfc
ridge. Main issue becomes the retreat of the stratus in the srn
terminals...OVC in DEC and BKN in both CMI and SPI, hanging close
to the MVFR/VFR break. Per vis sat imagery, the stratus erodes and
is replaced by a blooming cu field almost immediately. Given this
trend...am leaving current conditions until about an hour or two
before sunset as the cu field breaks up. For now, fog mention is
still MVFR, though the lingering llvl moisture in the south will
lend itself to lower vis in the srn terminals should it not be
able to mix out by max heating this afternoon.


&&

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

$$

SHORT TERM...HJS
LONG TERM...GOETSCH
AVIATION...HJS






000
FXUS63 KILX 161948
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
248 PM CDT Tue Sep 16 2014

.SHORT TERM...(Tonight)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure continues to build into the Midwest, and a cold front
is draped across the southern US. Tropical Storm Odile is over the
Gulf of California, parked just south of a 500mb ridge.  Forecast
for ILX is dominated by slow warming trend under the high, and
precip chances into next weekend.  Overnight, expecting quiet
weather and temperatures dropping into the mid-upper 40s. Only
concern will be the potential for fog, particularly in the
southeast, where stratocu have trapped some of the higher dwpts in
the region at the sfc.  Patchy fog in the forecast as a result in
the southeast, further north will still be possible, just not really
enough to mention at this time, provided the dwpts continue to mix
and drop a couple degrees.


&&

.LONG TERM...(Wednesday through Tuesday)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure to move off to the east over the Great Lakes on
Thursday and Friday. Cold front from the northern plains to reach
northern IA by early Saturday. Southerly flow ahead of the front
should bring ample moisture back into the area by the day Saturday.

Models differ some on the movement of the remains of Odile into the
southern plains. Moisture appears to be trending to make it into OK,
but should not reach into IL in time as the front should move in and
advect its remains southward.

The cold front is expected to move into region during the day
Saturday, with the main affects and associated precipitation on
Saturday night for central IL. Exiting precipitation on Sunday, so
gradually dropped pops down through the day.

A new high pressure center would then come in behind the front for
the start of next week.


&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
ISSUED AT 1222 PM CDT TUE SEP 16 2014
Light and variable winds throughout the pd under a building sfc
ridge. Main issue becomes the retreat of the stratus in the srn
terminals...OVC in DEC and BKN in both CMI and SPI, hanging close
to the MVFR/VFR break. Per vis sat imagery, the stratus erodes and
is replaced by a blooming cu field almost immediately. Given this
trend...am leaving current conditions until about an hour or two
before sunset as the cu field breaks up. For now, fog mention is
still MVFR, though the lingering llvl moisture in the south will
lend itself to lower vis in the srn terminals should it not be
able to mix out by max heating this afternoon.


&&

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

$$

SHORT TERM...HJS
LONG TERM...GOETSCH
AVIATION...HJS






000
FXUS63 KILX 161948
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
248 PM CDT Tue Sep 16 2014

.SHORT TERM...(Tonight)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure continues to build into the Midwest, and a cold front
is draped across the southern US. Tropical Storm Odile is over the
Gulf of California, parked just south of a 500mb ridge.  Forecast
for ILX is dominated by slow warming trend under the high, and
precip chances into next weekend.  Overnight, expecting quiet
weather and temperatures dropping into the mid-upper 40s. Only
concern will be the potential for fog, particularly in the
southeast, where stratocu have trapped some of the higher dwpts in
the region at the sfc.  Patchy fog in the forecast as a result in
the southeast, further north will still be possible, just not really
enough to mention at this time, provided the dwpts continue to mix
and drop a couple degrees.


&&

.LONG TERM...(Wednesday through Tuesday)
ISSUED AT 247 PM CDT TUE SEP 16 2014

High pressure to move off to the east over the Great Lakes on
Thursday and Friday. Cold front from the northern plains to reach
northern IA by early Saturday. Southerly flow ahead of the front
should bring ample moisture back into the area by the day Saturday.

Models differ some on the movement of the remains of Odile into the
southern plains. Moisture appears to be trending to make it into OK,
but should not reach into IL in time as the front should move in and
advect its remains southward.

The cold front is expected to move into region during the day
Saturday, with the main affects and associated precipitation on
Saturday night for central IL. Exiting precipitation on Sunday, so
gradually dropped pops down through the day.

A new high pressure center would then come in behind the front for
the start of next week.


&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
ISSUED AT 1222 PM CDT TUE SEP 16 2014
Light and variable winds throughout the pd under a building sfc
ridge. Main issue becomes the retreat of the stratus in the srn
terminals...OVC in DEC and BKN in both CMI and SPI, hanging close
to the MVFR/VFR break. Per vis sat imagery, the stratus erodes and
is replaced by a blooming cu field almost immediately. Given this
trend...am leaving current conditions until about an hour or two
before sunset as the cu field breaks up. For now, fog mention is
still MVFR, though the lingering llvl moisture in the south will
lend itself to lower vis in the srn terminals should it not be
able to mix out by max heating this afternoon.


&&

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

$$

SHORT TERM...HJS
LONG TERM...GOETSCH
AVIATION...HJS






000
FXUS63 KLOT 161929
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
229 PM CDT TUE SEP 16 2014

.DISCUSSION...
320 AM CDT

SHOULD SEE "CHAMBER OF COMMERCE" TYPE WEATHER FOR THE REMAINDER OF
THE WORK WEEK WITH A GRADUAL WARMING TREND. A PERIOD WARM AND STORMY
WEATHER IS ON TAP FOR THE WEEKEND BEFORE THE TRANSITION TO THE NEXT
COOL DOWN TAKES PLACE TOWARD END OF THE FORECAST CYCLE.

COOL CANADIAN HIGH PRESSURE WILL SLOWLY MOVE EASTWARD ACROSS THE
REGION THIS WEEK BRINGING A CONTINUATION OF BELOW AVERAGE
TEMPERATURES. ON THE PLUS SIDE...LOOKS LIKE THERE WILL BE AMPLE
SUNSHINE AND LITTLE THREAT OF RAIN THROUGH AT LEAST THURSDAY NIGHT
AND PROBABLY THROUGH FRIDAY AS WELL. WARM FRONT IS PROGGED TO MOVE
ACROSS THE REGION FRIDAY...WITH GFS/ECMWF BRINGING IT THROUGH DRY
FOLLOWED BY A BRIEF WARM UP LATER FRIDAY AND ESPECIALLY SATURDAY AS
TRANSIENT UPPER RIDGE MOVES ACROSS THE REGION IN ADVANCE OF
APPROACHING TROUGH. LATEST GFS/ECMWF PROGGED 850MB/925MB TEMPS WOULD
SUPPORT HIGHS IN THE LOW TO MID 80S...BUT A LOT COULD CHANGE BETWEEN
NOW AND THEN SO KEPT HIGHS MORE CONSERVATIVE FOR NOW AND FIGURE WE
CAN TREND TOWARD 80S IN LATER FORECASTS IF LATER RUNS WARRANT DOING
SO.

LATER SATURDAY INTO SATURDAY NIGHT GFS AND ECMWF BOTH PHASE THE
REMNANTS OF EASTERN PACIFIC HURRICANE ODILE WITH A DEEPENING
NORTHERN STRONG SHORTWAVE RESULTING IN PERIOD OF POTENTIALLY HEAVY
SHOWERS AND THUNDERSTORMS ALONG A COLD FRONT. PRETTY COMMON FOR
SIGNIFICANT AMPLIFICATION OF LONG WAVE TROUGHS AS THEY PHASE WITH
REMNANT TROPICAL CYCLONES...AND GFS AND ECMWF BOTH SUGGEST THIS WILL
BE THE CASE EARLY NEXT WEEK WITH THE POTENTIAL FOR ANOTHER
SIGNIFICANT EARLY SEASON COLD SNAP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* NONE.

KJB

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

AN AREA OF SURFACE HIGH PRESSURE WILL DOMINATE ACROSS THE REGION
THROUGH WEDNESDAY. OVERALL THIS WILL RESULT IN VERY LIGHT
WESTERLY WINDS...MAINLY CLEAR SKIES AND OVERALL NICE WEATHER
THROUGH THE FORECAST PERIOD. AFTERNOON LAKE BREEZES ARE EXPECTED
TODAY AND AGAIN ON WEDNESDAY. HOWEVER...IT APPEARS UNLIKELY THAT
THIS BOUNDARY WILL MAKE IT FAR ENOUGH INLAND TO IMPACT KORD OR
KMDW.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* HIGH FOR ALL ELEMENTS.

KJB

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

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.
SATURDAY...THUNDERSTORMS.
SUNDAY THROUGH MONDAY...VFR.

BMD

&&

.MARINE...
228 PM CDT

HIGH PRESSURE HAS BUILT ACROSS SOUTHERN LAKE MICHIGAN THIS
AFTERNOON. HOWEVER THE SOUTH TO SOUTHWEST GRADIENT HAS INCREASED
ACROSS THE NORTHERN HALF OF THE LAKE AHEAD OF THE NEXT COLD FRONT
OVER LAKE SUPERIOR. THE FRONT WILL SAG SOUTH ACROSS THE
LAKE FOR THE LATTER HALF OF WEDNESDAY INTO WEDNESDAY NIGHT. HIGH
PRESSURE IS RIGHT ON THE HEELS OF THIS FRONT CAUSING A SHARP
INCREASE IN WINDS BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF
THE NORTH-NORTHEAST WEDNESDAY EVENING. EXPECT WINDS WILL BE SLIGHTLY
LESS FARTHER SOUTH AS THE PRESSURE GRADIENT WILL NOT QUITE AS TIGHT
FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL VEER BACK AROUND TO
THE SOUTHEAST THURSDAY AND THURSDAY NIGHT WHILE DIMINISHING...THEN
BECOME SOUTH TO SOUTHWEST FRIDAY INCREASING INTO THE 25 TO 30 KT
RANGE AS BROAD LOW PRESSURE DEVELOPS OVER THE PLAINS AND CANADIAN
PRAIRIES. WINDS MAY STRENGTHEN TO NEAR GALE FORCE SUNDAY AS THE LOW
STRENGTHENS EAST TOWARD LAKE SUPERIOR THEN SHIFTS EAST.

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 161929
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
229 PM CDT TUE SEP 16 2014

.DISCUSSION...
320 AM CDT

SHOULD SEE "CHAMBER OF COMMERCE" TYPE WEATHER FOR THE REMAINDER OF
THE WORK WEEK WITH A GRADUAL WARMING TREND. A PERIOD WARM AND STORMY
WEATHER IS ON TAP FOR THE WEEKEND BEFORE THE TRANSITION TO THE NEXT
COOL DOWN TAKES PLACE TOWARD END OF THE FORECAST CYCLE.

COOL CANADIAN HIGH PRESSURE WILL SLOWLY MOVE EASTWARD ACROSS THE
REGION THIS WEEK BRINGING A CONTINUATION OF BELOW AVERAGE
TEMPERATURES. ON THE PLUS SIDE...LOOKS LIKE THERE WILL BE AMPLE
SUNSHINE AND LITTLE THREAT OF RAIN THROUGH AT LEAST THURSDAY NIGHT
AND PROBABLY THROUGH FRIDAY AS WELL. WARM FRONT IS PROGGED TO MOVE
ACROSS THE REGION FRIDAY...WITH GFS/ECMWF BRINGING IT THROUGH DRY
FOLLOWED BY A BRIEF WARM UP LATER FRIDAY AND ESPECIALLY SATURDAY AS
TRANSIENT UPPER RIDGE MOVES ACROSS THE REGION IN ADVANCE OF
APPROACHING TROUGH. LATEST GFS/ECMWF PROGGED 850MB/925MB TEMPS WOULD
SUPPORT HIGHS IN THE LOW TO MID 80S...BUT A LOT COULD CHANGE BETWEEN
NOW AND THEN SO KEPT HIGHS MORE CONSERVATIVE FOR NOW AND FIGURE WE
CAN TREND TOWARD 80S IN LATER FORECASTS IF LATER RUNS WARRANT DOING
SO.

LATER SATURDAY INTO SATURDAY NIGHT GFS AND ECMWF BOTH PHASE THE
REMNANTS OF EASTERN PACIFIC HURRICANE ODILE WITH A DEEPENING
NORTHERN STRONG SHORTWAVE RESULTING IN PERIOD OF POTENTIALLY HEAVY
SHOWERS AND THUNDERSTORMS ALONG A COLD FRONT. PRETTY COMMON FOR
SIGNIFICANT AMPLIFICATION OF LONG WAVE TROUGHS AS THEY PHASE WITH
REMNANT TROPICAL CYCLONES...AND GFS AND ECMWF BOTH SUGGEST THIS WILL
BE THE CASE EARLY NEXT WEEK WITH THE POTENTIAL FOR ANOTHER
SIGNIFICANT EARLY SEASON COLD SNAP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* NONE.

KJB

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

AN AREA OF SURFACE HIGH PRESSURE WILL DOMINATE ACROSS THE REGION
THROUGH WEDNESDAY. OVERALL THIS WILL RESULT IN VERY LIGHT
WESTERLY WINDS...MAINLY CLEAR SKIES AND OVERALL NICE WEATHER
THROUGH THE FORECAST PERIOD. AFTERNOON LAKE BREEZES ARE EXPECTED
TODAY AND AGAIN ON WEDNESDAY. HOWEVER...IT APPEARS UNLIKELY THAT
THIS BOUNDARY WILL MAKE IT FAR ENOUGH INLAND TO IMPACT KORD OR
KMDW.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* HIGH FOR ALL ELEMENTS.

KJB

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

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.
SATURDAY...THUNDERSTORMS.
SUNDAY THROUGH MONDAY...VFR.

BMD

&&

.MARINE...
228 PM CDT

HIGH PRESSURE HAS BUILT ACROSS SOUTHERN LAKE MICHIGAN THIS
AFTERNOON. HOWEVER THE SOUTH TO SOUTHWEST GRADIENT HAS INCREASED
ACROSS THE NORTHERN HALF OF THE LAKE AHEAD OF THE NEXT COLD FRONT
OVER LAKE SUPERIOR. THE FRONT WILL SAG SOUTH ACROSS THE
LAKE FOR THE LATTER HALF OF WEDNESDAY INTO WEDNESDAY NIGHT. HIGH
PRESSURE IS RIGHT ON THE HEELS OF THIS FRONT CAUSING A SHARP
INCREASE IN WINDS BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF
THE NORTH-NORTHEAST WEDNESDAY EVENING. EXPECT WINDS WILL BE SLIGHTLY
LESS FARTHER SOUTH AS THE PRESSURE GRADIENT WILL NOT QUITE AS TIGHT
FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL VEER BACK AROUND TO
THE SOUTHEAST THURSDAY AND THURSDAY NIGHT WHILE DIMINISHING...THEN
BECOME SOUTH TO SOUTHWEST FRIDAY INCREASING INTO THE 25 TO 30 KT
RANGE AS BROAD LOW PRESSURE DEVELOPS OVER THE PLAINS AND CANADIAN
PRAIRIES. WINDS MAY STRENGTHEN TO NEAR GALE FORCE SUNDAY AS THE LOW
STRENGTHENS EAST TOWARD LAKE SUPERIOR THEN SHIFTS EAST.

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 161929
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
229 PM CDT TUE SEP 16 2014

.DISCUSSION...
320 AM CDT

SHOULD SEE "CHAMBER OF COMMERCE" TYPE WEATHER FOR THE REMAINDER OF
THE WORK WEEK WITH A GRADUAL WARMING TREND. A PERIOD WARM AND STORMY
WEATHER IS ON TAP FOR THE WEEKEND BEFORE THE TRANSITION TO THE NEXT
COOL DOWN TAKES PLACE TOWARD END OF THE FORECAST CYCLE.

COOL CANADIAN HIGH PRESSURE WILL SLOWLY MOVE EASTWARD ACROSS THE
REGION THIS WEEK BRINGING A CONTINUATION OF BELOW AVERAGE
TEMPERATURES. ON THE PLUS SIDE...LOOKS LIKE THERE WILL BE AMPLE
SUNSHINE AND LITTLE THREAT OF RAIN THROUGH AT LEAST THURSDAY NIGHT
AND PROBABLY THROUGH FRIDAY AS WELL. WARM FRONT IS PROGGED TO MOVE
ACROSS THE REGION FRIDAY...WITH GFS/ECMWF BRINGING IT THROUGH DRY
FOLLOWED BY A BRIEF WARM UP LATER FRIDAY AND ESPECIALLY SATURDAY AS
TRANSIENT UPPER RIDGE MOVES ACROSS THE REGION IN ADVANCE OF
APPROACHING TROUGH. LATEST GFS/ECMWF PROGGED 850MB/925MB TEMPS WOULD
SUPPORT HIGHS IN THE LOW TO MID 80S...BUT A LOT COULD CHANGE BETWEEN
NOW AND THEN SO KEPT HIGHS MORE CONSERVATIVE FOR NOW AND FIGURE WE
CAN TREND TOWARD 80S IN LATER FORECASTS IF LATER RUNS WARRANT DOING
SO.

LATER SATURDAY INTO SATURDAY NIGHT GFS AND ECMWF BOTH PHASE THE
REMNANTS OF EASTERN PACIFIC HURRICANE ODILE WITH A DEEPENING
NORTHERN STRONG SHORTWAVE RESULTING IN PERIOD OF POTENTIALLY HEAVY
SHOWERS AND THUNDERSTORMS ALONG A COLD FRONT. PRETTY COMMON FOR
SIGNIFICANT AMPLIFICATION OF LONG WAVE TROUGHS AS THEY PHASE WITH
REMNANT TROPICAL CYCLONES...AND GFS AND ECMWF BOTH SUGGEST THIS WILL
BE THE CASE EARLY NEXT WEEK WITH THE POTENTIAL FOR ANOTHER
SIGNIFICANT EARLY SEASON COLD SNAP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* NONE.

KJB

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

AN AREA OF SURFACE HIGH PRESSURE WILL DOMINATE ACROSS THE REGION
THROUGH WEDNESDAY. OVERALL THIS WILL RESULT IN VERY LIGHT
WESTERLY WINDS...MAINLY CLEAR SKIES AND OVERALL NICE WEATHER
THROUGH THE FORECAST PERIOD. AFTERNOON LAKE BREEZES ARE EXPECTED
TODAY AND AGAIN ON WEDNESDAY. HOWEVER...IT APPEARS UNLIKELY THAT
THIS BOUNDARY WILL MAKE IT FAR ENOUGH INLAND TO IMPACT KORD OR
KMDW.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* HIGH FOR ALL ELEMENTS.

KJB

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

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.
SATURDAY...THUNDERSTORMS.
SUNDAY THROUGH MONDAY...VFR.

BMD

&&

.MARINE...
228 PM CDT

HIGH PRESSURE HAS BUILT ACROSS SOUTHERN LAKE MICHIGAN THIS
AFTERNOON. HOWEVER THE SOUTH TO SOUTHWEST GRADIENT HAS INCREASED
ACROSS THE NORTHERN HALF OF THE LAKE AHEAD OF THE NEXT COLD FRONT
OVER LAKE SUPERIOR. THE FRONT WILL SAG SOUTH ACROSS THE
LAKE FOR THE LATTER HALF OF WEDNESDAY INTO WEDNESDAY NIGHT. HIGH
PRESSURE IS RIGHT ON THE HEELS OF THIS FRONT CAUSING A SHARP
INCREASE IN WINDS BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF
THE NORTH-NORTHEAST WEDNESDAY EVENING. EXPECT WINDS WILL BE SLIGHTLY
LESS FARTHER SOUTH AS THE PRESSURE GRADIENT WILL NOT QUITE AS TIGHT
FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL VEER BACK AROUND TO
THE SOUTHEAST THURSDAY AND THURSDAY NIGHT WHILE DIMINISHING...THEN
BECOME SOUTH TO SOUTHWEST FRIDAY INCREASING INTO THE 25 TO 30 KT
RANGE AS BROAD LOW PRESSURE DEVELOPS OVER THE PLAINS AND CANADIAN
PRAIRIES. WINDS MAY STRENGTHEN TO NEAR GALE FORCE SUNDAY AS THE LOW
STRENGTHENS EAST TOWARD LAKE SUPERIOR THEN SHIFTS EAST.

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 161929
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
229 PM CDT TUE SEP 16 2014

.DISCUSSION...
320 AM CDT

SHOULD SEE "CHAMBER OF COMMERCE" TYPE WEATHER FOR THE REMAINDER OF
THE WORK WEEK WITH A GRADUAL WARMING TREND. A PERIOD WARM AND STORMY
WEATHER IS ON TAP FOR THE WEEKEND BEFORE THE TRANSITION TO THE NEXT
COOL DOWN TAKES PLACE TOWARD END OF THE FORECAST CYCLE.

COOL CANADIAN HIGH PRESSURE WILL SLOWLY MOVE EASTWARD ACROSS THE
REGION THIS WEEK BRINGING A CONTINUATION OF BELOW AVERAGE
TEMPERATURES. ON THE PLUS SIDE...LOOKS LIKE THERE WILL BE AMPLE
SUNSHINE AND LITTLE THREAT OF RAIN THROUGH AT LEAST THURSDAY NIGHT
AND PROBABLY THROUGH FRIDAY AS WELL. WARM FRONT IS PROGGED TO MOVE
ACROSS THE REGION FRIDAY...WITH GFS/ECMWF BRINGING IT THROUGH DRY
FOLLOWED BY A BRIEF WARM UP LATER FRIDAY AND ESPECIALLY SATURDAY AS
TRANSIENT UPPER RIDGE MOVES ACROSS THE REGION IN ADVANCE OF
APPROACHING TROUGH. LATEST GFS/ECMWF PROGGED 850MB/925MB TEMPS WOULD
SUPPORT HIGHS IN THE LOW TO MID 80S...BUT A LOT COULD CHANGE BETWEEN
NOW AND THEN SO KEPT HIGHS MORE CONSERVATIVE FOR NOW AND FIGURE WE
CAN TREND TOWARD 80S IN LATER FORECASTS IF LATER RUNS WARRANT DOING
SO.

LATER SATURDAY INTO SATURDAY NIGHT GFS AND ECMWF BOTH PHASE THE
REMNANTS OF EASTERN PACIFIC HURRICANE ODILE WITH A DEEPENING
NORTHERN STRONG SHORTWAVE RESULTING IN PERIOD OF POTENTIALLY HEAVY
SHOWERS AND THUNDERSTORMS ALONG A COLD FRONT. PRETTY COMMON FOR
SIGNIFICANT AMPLIFICATION OF LONG WAVE TROUGHS AS THEY PHASE WITH
REMNANT TROPICAL CYCLONES...AND GFS AND ECMWF BOTH SUGGEST THIS WILL
BE THE CASE EARLY NEXT WEEK WITH THE POTENTIAL FOR ANOTHER
SIGNIFICANT EARLY SEASON COLD SNAP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* NONE.

KJB

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

AN AREA OF SURFACE HIGH PRESSURE WILL DOMINATE ACROSS THE REGION
THROUGH WEDNESDAY. OVERALL THIS WILL RESULT IN VERY LIGHT
WESTERLY WINDS...MAINLY CLEAR SKIES AND OVERALL NICE WEATHER
THROUGH THE FORECAST PERIOD. AFTERNOON LAKE BREEZES ARE EXPECTED
TODAY AND AGAIN ON WEDNESDAY. HOWEVER...IT APPEARS UNLIKELY THAT
THIS BOUNDARY WILL MAKE IT FAR ENOUGH INLAND TO IMPACT KORD OR
KMDW.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* HIGH FOR ALL ELEMENTS.

KJB

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

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.
SATURDAY...THUNDERSTORMS.
SUNDAY THROUGH MONDAY...VFR.

BMD

&&

.MARINE...
228 PM CDT

HIGH PRESSURE HAS BUILT ACROSS SOUTHERN LAKE MICHIGAN THIS
AFTERNOON. HOWEVER THE SOUTH TO SOUTHWEST GRADIENT HAS INCREASED
ACROSS THE NORTHERN HALF OF THE LAKE AHEAD OF THE NEXT COLD FRONT
OVER LAKE SUPERIOR. THE FRONT WILL SAG SOUTH ACROSS THE
LAKE FOR THE LATTER HALF OF WEDNESDAY INTO WEDNESDAY NIGHT. HIGH
PRESSURE IS RIGHT ON THE HEELS OF THIS FRONT CAUSING A SHARP
INCREASE IN WINDS BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF
THE NORTH-NORTHEAST WEDNESDAY EVENING. EXPECT WINDS WILL BE SLIGHTLY
LESS FARTHER SOUTH AS THE PRESSURE GRADIENT WILL NOT QUITE AS TIGHT
FOR THE SOUTHERN HALF OF THE LAKE. WINDS WILL VEER BACK AROUND TO
THE SOUTHEAST THURSDAY AND THURSDAY NIGHT WHILE DIMINISHING...THEN
BECOME SOUTH TO SOUTHWEST FRIDAY INCREASING INTO THE 25 TO 30 KT
RANGE AS BROAD LOW PRESSURE DEVELOPS OVER THE PLAINS AND CANADIAN
PRAIRIES. WINDS MAY STRENGTHEN TO NEAR GALE FORCE SUNDAY AS THE LOW
STRENGTHENS EAST TOWARD LAKE SUPERIOR THEN SHIFTS EAST.

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 161725
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1225 PM CDT Tue Sep 16 2014

.UPDATE...
ISSUED AT 1045 AM CDT TUE SEP 16 2014
High pressure building into the region will keep the weather quiet
and rather non-eventful throughout today. Stratus slowly
retreating to the south as cooler air filters in. Temps on track
for highs into the 60s, with mostly sunny across the nrn portions
of the state... and mostly cloudy and slowly clearing in the
southern half. Most cu development should be tempered a bit in the
north by synoptic subsidence. The southern half of the state will
likely see more in the way of cu, as seen on current vis sat
imagery. Very minor adjustments to the hourly grids and no update
anticipated at this time.

&&

.SHORT TERM...(Today)
ISSUED AT 230 AM CDT TUE SEP 16 2014

Quiet weather expected overall today across central and southeast
Illinois. Canadian high pressure and its associated dry air mass will
continue to build into the area today, helping to scour out the low
clouds that currently reside across much of the forecast area. The
low clouds have been clearing slowly from the north as the high
builds in, and the latest trends suggest the clearing should reach
the I-70 corridor by 10 a.m. this morning. Once the skies clear,
mostly sunny skies should be the rule, as forecast soundings and CU
rule suggest diurnal cloud development should be minimal. The
possible exception to the clearing sticking, at least until sunrise,
is the potential for fog/stratus development. This development has
been patchy thus far upstream, and do not expect it to become too
widespread. Temperatures today, as they have been more often than
not lately, will be well below normal with highs mainly in the
mid-upper 60s.

&&

.LONG TERM...(Tonight through Monday)
ISSUED AT 230 AM CDT TUE SEP 16 2014

High pressure building southeast into the Great Lakes to dominate
our weather through Thursday. Latest model guidance continues to
indicate some sort of MCS type activity across Missouri and Kansas
Wednesday into Thursday, sliding along the edge of the upper ridge
that will slowly inch eastward into the Plains. However, the
persistent east/northeast flow over our area should keep this
precipitation at bay.

Significant shortwave will dig as it crosses the Rockies on Friday,
settling into the Mississippi Valley by Sunday morning. Have largely
kept the forecast dry through about midday Saturday, then quickly
increased the PoP`s from west to east during the afternoon and
evening hours, as the front arrives. One significant item of concern
is with the potential for heavy rain. The remnants of tropical
cyclone Odile over Baja California will be spreading into the Desert
Southwest over the next day or so. The latest GFS model continues to
show that a piece of energy and associated moisture from this system
will be drawn northeast into the northern wave, reaching central
Illinois after midnight Saturday night with the potential for a few
inches of rain. The ECMWF and Canadian models are not quite as
generous on this point, but do draw in some of the moisture into the
wave by Saturday morning and produce weekend rainfalls of up to 1.5
inches. Have increased PoP`s Saturday night to around 60% across
most of the forecast area, as confidence increases in the general
rainfall trend over the area. Continued the PoP`s on Sunday east of
I-55, although this should be winding down during the afternoon as
the front exits the area.

A large broad upper trough will persist over the Midwest early next
week in the wake of this system. Latest ECMWF model has
significantly backed down on the amount of cool air with this
system, with 850 mb temperatures on Monday now around +5C rather
than the -2C from the previous run. The GFS lags behind the ECMWF
with bringing the cooler conditions into the area. As a result, have
kept highs in the 70s on Sunday and Monday, with the coolest
conditions just beyond the current forecast period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
ISSUED AT 1222 PM CDT TUE SEP 16 2014
Light and variable winds throughout the pd under a building sfc
ridge. Main issue becomes the retreat of the stratus in the srn
terminals...OVC in DEC and BKN in both CMI and SPI, hanging close
to the MVFR/VFR break. Per vis sat imagery, the stratus erodes and
is replaced by a blooming cu field almost immediately. Given this
trend...am leaving current conditions until about an hour or two
before sunset as the cu field breaks up. For now, fog mention is
still MVFR, though the lingering llvl moisture in the south will
lend itself to lower vis in the srn terminals should it not be
able to mix out by max heating this afternoon.

&&

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

$$

UPDATE...HJS
SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...HJS






000
FXUS63 KLOT 161656
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1156 AM CDT TUE SEP 16 2014

.DISCUSSION...
320 AM CDT

SHOULD SEE "CHAMBER OF COMMERCE" TYPE WEATHER FOR THE REMAINDER OF
THE WORK WEEK WITH A GRADUAL WARMING TREND. A PERIOD WARM AND STORMY
WEATHER IS ON TAP FOR THE WEEKEND BEFORE THE TRANSITION TO THE NEXT
COOL DOWN TAKES PLACE TOWARD END OF THE FORECAST CYCLE.

COOL CANADIAN HIGH PRESSURE WILL SLOWLY MOVE EASTWARD ACROSS THE
REGION THIS WEEK BRINGING A CONTINUATION OF BELOW AVERAGE
TEMPERATURES. ON THE PLUS SIDE...LOOKS LIKE THERE WILL BE AMPLE
SUNSHINE AND LITTLE THREAT OF RAIN THROUGH AT LEAST THURSDAY NIGHT
AND PROBABLY THROUGH FRIDAY AS WELL. WARM FRONT IS PROGGED TO MOVE
ACROSS THE REGION FRIDAY...WITH GFS/ECMWF BRINGING IT THROUGH DRY
FOLLOWED BY A BRIEF WARM UP LATER FRIDAY AND ESPECIALLY SATURDAY AS
TRANSIENT UPPER RIDGE MOVES ACROSS THE REGION IN ADVANCE OF
APPROACHING TROUGH. LATEST GFS/ECMWF PROGGED 850MB/925MB TEMPS WOULD
SUPPORT HIGHS IN THE LOW TO MID 80S...BUT A LOT COULD CHANGE BETWEEN
NOW AND THEN SO KEPT HIGHS MORE CONSERVATIVE FOR NOW AND FIGURE WE
CAN TREND TOWARD 80S IN LATER FORECASTS IF LATER RUNS WARRANT DOING
SO.

LATER SATURDAY INTO SATURDAY NIGHT GFS AND ECMWF BOTH PHASE THE
REMNANTS OF EASTERN PACIFIC HURRICANE ODILE WITH A DEEPENING
NORTHERN STRONG SHORTWAVE RESULTING IN PERIOD OF POTENTIALLY HEAVY
SHOWERS AND THUNDERSTORMS ALONG A COLD FRONT. PRETTY COMMON FOR
SIGNIFICANT AMPLIFICATION OF LONG WAVE TROUGHS AS THEY PHASE WITH
REMNANT TROPICAL CYCLONES...AND GFS AND ECMWF BOTH SUGGEST THIS WILL
BE THE CASE EARLY NEXT WEEK WITH THE POTENTIAL FOR ANOTHER
SIGNIFICANT EARLY SEASON COLD SNAP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* NONE.

KJB

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

AN AREA OF SURFACE HIGH PRESSURE WILL DOMINATE ACROSS THE REGION
THROUGH WEDNESDAY. OVERALL THIS WILL RESULT IN VERY LIGHT
WESTERLY WINDS...MAINLY CLEAR SKIES AND OVERALL NICE WEATHER
THROUGH THE FORECAST PERIOD. AFTERNOON LAKE BREEZES ARE EXPECTED
TODAY AND AGAIN ON WEDNESDAY. HOWEVER...IT APPEARS UNLIKELY THAT
THIS BOUNDARY WILL MAKE IT FAR ENOUGH INLAND TO IMPACT KORD OR
KMDW.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* HIGH FOR ALL ELEMENTS.

KJB

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

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.
SATURDAY...THUNDERSTORMS.
SUNDAY THROUGH MONDAY...VFR.

BMD

&&

.MARINE...
314 AM CDT

HIGH PRESSURE WILL BUILD ACROSS SOUTHERN LAKE MICHIGAN TODAY
ALLOWING WINDS TO DIMINISH...HOWEVER NORTHERN LAKE MICHIGAN WILL
SEE SOUTHWEST FLOW FRESHEN UP AHEAD OF THE NEXT COLD FRONT. THE
FRONT WILL SAG SOUTH ACROSS THE LAKE WEDNESDAY WITH HIGH PRESSURE
QUICKLY BUILDING IN BEHIND CAUSING A SHARP INCREASE IN WINDS
BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF THE NORTHEAST
WEDNESDAY EVENING. WINDS WILL VEER BACK AROUND TO THE SOUTHEAST
THURSDAY AND THURSDAY NIGHT DIMINISHING...THEN SOUTH TO SOUTHWEST
FRIDAY INCREASING BACK INTO THE 20 TO 25 KT RANGE...POSSIBLY 30 KT
AS BROAD LOW DEVELOPS OVER THE PLAINS AND CANADIAN PRAIRIES.

BMD

&&

.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 161557
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1057 AM CDT TUE SEP 16 2014

.DISCUSSION...
320 AM CDT

SHOULD SEE "CHAMBER OF COMMERCE" TYPE WEATHER FOR THE REMAINDER OF
THE WORK WEEK WITH A GRADUAL WARMING TREND. A PERIOD WARM AND STORMY
WEATHER IS ON TAP FOR THE WEEKEND BEFORE THE TRANSITION TO THE NEXT
COOL DOWN TAKES PLACE TOWARD END OF THE FORECAST CYCLE.

COOL CANADIAN HIGH PRESSURE WILL SLOWLY MOVE EASTWARD ACROSS THE
REGION THIS WEEK BRINGING A CONTINUATION OF BELOW AVERAGE
TEMPERATURES. ON THE PLUS SIDE...LOOKS LIKE THERE WILL BE AMPLE
SUNSHINE AND LITTLE THREAT OF RAIN THROUGH AT LEAST THURSDAY NIGHT
AND PROBABLY THROUGH FRIDAY AS WELL. WARM FRONT IS PROGGED TO MOVE
ACROSS THE REGION FRIDAY...WITH GFS/ECMWF BRINGING IT THROUGH DRY
FOLLOWED BY A BRIEF WARM UP LATER FRIDAY AND ESPECIALLY SATURDAY AS
TRANSIENT UPPER RIDGE MOVES ACROSS THE REGION IN ADVANCE OF
APPROACHING TROUGH. LATEST GFS/ECMWF PROGGED 850MB/925MB TEMPS WOULD
SUPPORT HIGHS IN THE LOW TO MID 80S...BUT A LOT COULD CHANGE BETWEEN
NOW AND THEN SO KEPT HIGHS MORE CONSERVATIVE FOR NOW AND FIGURE WE
CAN TREND TOWARD 80S IN LATER FORECASTS IF LATER RUNS WARRANT DOING
SO.

LATER SATURDAY INTO SATURDAY NIGHT GFS AND ECMWF BOTH PHASE THE
REMNANTS OF EASTERN PACIFIC HURRICANE ODILE WITH A DEEPENING
NORTHERN STRONG SHORTWAVE RESULTING IN PERIOD OF POTENTIALLY HEAVY
SHOWERS AND THUNDERSTORMS ALONG A COLD FRONT. PRETTY COMMON FOR
SIGNIFICANT AMPLIFICATION OF LONG WAVE TROUGHS AS THEY PHASE WITH
REMNANT TROPICAL CYCLONES...AND GFS AND ECMWF BOTH SUGGEST THIS WILL
BE THE CASE EARLY NEXT WEEK WITH THE POTENTIAL FOR ANOTHER
SIGNIFICANT EARLY SEASON COLD SNAP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* NONE.

KB

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

HIGH PRESSURE WILL RESULT IN LIGHT WINDS AND PRIMARILY VFR
CONDITIONS THROUGH THE FORECAST PERIOD...WITH THE EXCEPTION OF SOME
PATCHY GROUND FOG DURING THE EARLY MORNING HOURS MAINLY AT THE
OUTLYING TERMINALS. WINDS WILL GENERALLY BE SOME SORT OF
NORTHWESTERLY DIRECTION THROUGH MIDDAY THOUGH THERE WILL LIKELY BE
VARIABILITY DUE TO THE LIGHT MAGNITUDE. WINDS SHOULD FAVOR A MORE
WESTERLY DIRECTION THIS AFTERNOON/EVENING. A LAKE BREEZE IS POSSIBLE
THIS AFTERNOON...THOUGH WEAK THERMAL CONTRAST AND OPPOSING FLOW
SHOULD KEEP IT FROM PUSHING IN ACROSS THE TERMINALS.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* HIGH WITH ALL FORECAST ELEMENTS.

KB

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

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.
SATURDAY...THUNDERSTORMS.
SUNDAY THROUGH MONDAY...VFR.

BMD

&&

.MARINE...
314 AM CDT

HIGH PRESSURE WILL BUILD ACROSS SOUTHERN LAKE MICHIGAN TODAY
ALLOWING WINDS TO DIMINISH...HOWEVER NORTHERN LAKE MICHIGAN WILL
SEE SOUTHWEST FLOW FRESHEN UP AHEAD OF THE NEXT COLD FRONT. THE
FRONT WILL SAG SOUTH ACROSS THE LAKE WEDNESDAY WITH HIGH PRESSURE
QUICKLY BUILDING IN BEHIND CAUSING A SHARP INCREASE IN WINDS
BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF THE NORTHEAST
WEDNESDAY EVENING. WINDS WILL VEER BACK AROUND TO THE SOUTHEAST
THURSDAY AND THURSDAY NIGHT DIMINISHING...THEN SOUTH TO SOUTHWEST
FRIDAY INCREASING BACK INTO THE 20 TO 25 KT RANGE...POSSIBLY 30 KT
AS BROAD LOW DEVELOPS OVER THE PLAINS AND CANADIAN PRAIRIES.

BMD

&&

.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 161549
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1049 AM CDT Tue Sep 16 2014

.UPDATE...
ISSUED AT 1045 AM CDT TUE SEP 16 2014
High pressure building into the region will keep the weather quiet
and rather non-eventful throughout today. Stratus slowly
retreating to the south as cooler air filters in. Temps on track
for highs into the 60s, with mostly sunny across the nrn portions
of the state... and mostly cloudy and slowly clearing in the
southern half. Most cu development should be tempered a bit in the
north by synoptic subsidence. The southern half of the state will
likely see more in the way of cu, as seen on current vis sat
imagery. Very minor adjustments to the hourly grids and no update
anticipated at this time.

&&

.SHORT TERM...(Today)
ISSUED AT 230 AM CDT TUE SEP 16 2014

Quiet weather expected overall today across central and southeast
Illinois. Canadian high pressure and its associated dry air mass will
continue to build into the area today, helping to scour out the low
clouds that currently reside across much of the forecast area. The
low clouds have been clearing slowly from the north as the high
builds in, and the latest trends suggest the clearing should reach
the I-70 corridor by 10 a.m. this morning. Once the skies clear,
mostly sunny skies should be the rule, as forecast soundings and CU
rule suggest diurnal cloud development should be minimal. The
possible exception to the clearing sticking, at least until sunrise,
is the potential for fog/stratus development. This development has
been patchy thus far upstream, and do not expect it to become too
widespread. Temperatures today, as they have been more often than
not lately, will be well below normal with highs mainly in the
mid-upper 60s.

&&

.LONG TERM...(Tonight through Monday)
ISSUED AT 230 AM CDT TUE SEP 16 2014

High pressure building southeast into the Great Lakes to dominate
our weather through Thursday. Latest model guidance continues to
indicate some sort of MCS type activity across Missouri and Kansas
Wednesday into Thursday, sliding along the edge of the upper ridge
that will slowly inch eastward into the Plains. However, the
persistent east/northeast flow over our area should keep this
precipitation at bay.

Significant shortwave will dig as it crosses the Rockies on Friday,
settling into the Mississippi Valley by Sunday morning. Have largely
kept the forecast dry through about midday Saturday, then quickly
increased the PoP`s from west to east during the afternoon and
evening hours, as the front arrives. One significant item of concern
is with the potential for heavy rain. The remnants of tropical
cyclone Odile over Baja California will be spreading into the Desert
Southwest over the next day or so. The latest GFS model continues to
show that a piece of energy and associated moisture from this system
will be drawn northeast into the northern wave, reaching central
Illinois after midnight Saturday night with the potential for a few
inches of rain. The ECMWF and Canadian models are not quite as
generous on this point, but do draw in some of the moisture into the
wave by Saturday morning and produce weekend rainfalls of up to 1.5
inches. Have increased PoP`s Saturday night to around 60% across
most of the forecast area, as confidence increases in the general
rainfall trend over the area. Continued the PoP`s on Sunday east of
I-55, although this should be winding down during the afternoon as
the front exits the area.

A large broad upper trough will persist over the Midwest early next
week in the wake of this system. Latest ECMWF model has
significantly backed down on the amount of cool air with this
system, with 850 mb temperatures on Monday now around +5C rather
than the -2C from the previous run. The GFS lags behind the ECMWF
with bringing the cooler conditions into the area. As a result, have
kept highs in the 70s on Sunday and Monday, with the coolest
conditions just beyond the current forecast period.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
ISSUED AT 655 AM CDT TUE SEP 16 2014

Generally quiet/VFR aviation weather conditions expected across
the central Illinois terminals through the 12Z TAF valid time.
The primary exception will be early this morning. A large area of
post-frontal IFR/MVFR cigs have dropped just south of the area,
but patchy stratus/fog have developed in its wake. While an hour
or two of IFR/MVFR conditions are possible over the next couple
hours, it should burn off quickly as the sun continues to rise.
Otherwise, cloud cover should be minimal. Patchy fog is possible
again late tonight, but a day of nearly full sun should keep
chances minimal. The arrival of the center of the surface high
should keep winds light/variable overall.


&&

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

$$

UPDATE...HJS
SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...BAK






000
FXUS63 KILX 161549
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1049 AM CDT Tue Sep 16 2014

.UPDATE...
ISSUED AT 1045 AM CDT TUE SEP 16 2014
High pressure building into the region will keep the weather quiet
and rather non-eventful throughout today. Stratus slowly
retreating to the south as cooler air filters in. Temps on track
for highs into the 60s, with mostly sunny across the nrn portions
of the state... and mostly cloudy and slowly clearing in the
southern half. Most cu development should be tempered a bit in the
north by synoptic subsidence. The southern half of the state will
likely see more in the way of cu, as seen on current vis sat
imagery. Very minor adjustments to the hourly grids and no update
anticipated at this time.

&&

.SHORT TERM...(Today)
ISSUED AT 230 AM CDT TUE SEP 16 2014

Quiet weather expected overall today across central and southeast
Illinois. Canadian high pressure and its associated dry air mass will
continue to build into the area today, helping to scour out the low
clouds that currently reside across much of the forecast area. The
low clouds have been clearing slowly from the north as the high
builds in, and the latest trends suggest the clearing should reach
the I-70 corridor by 10 a.m. this morning. Once the skies clear,
mostly sunny skies should be the rule, as forecast soundings and CU
rule suggest diurnal cloud development should be minimal. The
possible exception to the clearing sticking, at least until sunrise,
is the potential for fog/stratus development. This development has
been patchy thus far upstream, and do not expect it to become too
widespread. Temperatures today, as they have been more often than
not lately, will be well below normal with highs mainly in the
mid-upper 60s.

&&

.LONG TERM...(Tonight through Monday)
ISSUED AT 230 AM CDT TUE SEP 16 2014

High pressure building southeast into the Great Lakes to dominate
our weather through Thursday. Latest model guidance continues to
indicate some sort of MCS type activity across Missouri and Kansas
Wednesday into Thursday, sliding along the edge of the upper ridge
that will slowly inch eastward into the Plains. However, the
persistent east/northeast flow over our area should keep this
precipitation at bay.

Significant shortwave will dig as it crosses the Rockies on Friday,
settling into the Mississippi Valley by Sunday morning. Have largely
kept the forecast dry through about midday Saturday, then quickly
increased the PoP`s from west to east during the afternoon and
evening hours, as the front arrives. One significant item of concern
is with the potential for heavy rain. The remnants of tropical
cyclone Odile over Baja California will be spreading into the Desert
Southwest over the next day or so. The latest GFS model continues to
show that a piece of energy and associated moisture from this system
will be drawn northeast into the northern wave, reaching central
Illinois after midnight Saturday night with the potential for a few
inches of rain. The ECMWF and Canadian models are not quite as
generous on this point, but do draw in some of the moisture into the
wave by Saturday morning and produce weekend rainfalls of up to 1.5
inches. Have increased PoP`s Saturday night to around 60% across
most of the forecast area, as confidence increases in the general
rainfall trend over the area. Continued the PoP`s on Sunday east of
I-55, although this should be winding down during the afternoon as
the front exits the area.

A large broad upper trough will persist over the Midwest early next
week in the wake of this system. Latest ECMWF model has
significantly backed down on the amount of cool air with this
system, with 850 mb temperatures on Monday now around +5C rather
than the -2C from the previous run. The GFS lags behind the ECMWF
with bringing the cooler conditions into the area. As a result, have
kept highs in the 70s on Sunday and Monday, with the coolest
conditions just beyond the current forecast period.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
ISSUED AT 655 AM CDT TUE SEP 16 2014

Generally quiet/VFR aviation weather conditions expected across
the central Illinois terminals through the 12Z TAF valid time.
The primary exception will be early this morning. A large area of
post-frontal IFR/MVFR cigs have dropped just south of the area,
but patchy stratus/fog have developed in its wake. While an hour
or two of IFR/MVFR conditions are possible over the next couple
hours, it should burn off quickly as the sun continues to rise.
Otherwise, cloud cover should be minimal. Patchy fog is possible
again late tonight, but a day of nearly full sun should keep
chances minimal. The arrival of the center of the surface high
should keep winds light/variable overall.


&&

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

$$

UPDATE...HJS
SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...BAK







000
FXUS63 KLOT 161348
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
848 AM CDT TUE SEP 16 2014

.DISCUSSION...
320 AM CDT

SHOULD SEE "CHAMBER OF COMMERCE" TYPE WEATHER FOR THE REMAINDER OF
THE WORK WEEK WITH A GRADUAL WARMING TREND. A PERIOD WARM AND STORMY
WEATHER IS ON TAP FOR THE WEEKEND BEFORE THE TRANSITION TO THE NEXT
COOL DOWN TAKES PLACE TOWARD END OF THE FORECAST CYCLE.

COOL CANADIAN HIGH PRESSURE WILL SLOWLY MOVE EASTWARD ACROSS THE
REGION THIS WEEK BRINGING A CONTINUATION OF BELOW AVERAGE
TEMPERATURES. ON THE PLUS SIDE...LOOKS LIKE THERE WILL BE AMPLE
SUNSHINE AND LITTLE THREAT OF RAIN THROUGH AT LEAST THURSDAY NIGHT
AND PROBABLY THROUGH FRIDAY AS WELL. WARM FRONT IS PROGGED TO MOVE
ACROSS THE REGION FRIDAY...WITH GFS/ECMWF BRINGING IT THROUGH DRY
FOLLOWED BY A BRIEF WARM UP LATER FRIDAY AND ESPECIALLY SATURDAY AS
TRANSIENT UPPER RIDGE MOVES ACROSS THE REGION IN ADVANCE OF
APPROACHING TROUGH. LATEST GFS/ECMWF PROGGED 850MB/925MB TEMPS WOULD
SUPPORT HIGHS IN THE LOW TO MID 80S...BUT A LOT COULD CHANGE BETWEEN
NOW AND THEN SO KEPT HIGHS MORE CONSERVATIVE FOR NOW AND FIGURE WE
CAN TREND TOWARD 80S IN LATER FORECASTS IF LATER RUNS WARRANT DOING
SO.

LATER SATURDAY INTO SATURDAY NIGHT GFS AND ECMWF BOTH PHASE THE
REMNANTS OF EASTERN PACIFIC HURRICANE ODILE WITH A DEEPENING
NORTHERN STRONG SHORTWAVE RESULTING IN PERIOD OF POTENTIALLY HEAVY
SHOWERS AND THUNDERSTORMS ALONG A COLD FRONT. PRETTY COMMON FOR
SIGNIFICANT AMPLIFICATION OF LONG WAVE TROUGHS AS THEY PHASE WITH
REMNANT TROPICAL CYCLONES...AND GFS AND ECMWF BOTH SUGGEST THIS WILL
BE THE CASE EARLY NEXT WEEK WITH THE POTENTIAL FOR ANOTHER
SIGNIFICANT EARLY SEASON COLD SNAP.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 14Z...

* NONE.

KB

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

HIGH PRESSURE WILL RESULT IN LIGHT WINDS AND PRIMARILY VFR
CONDITIONS THROUGH THE FORECAST PERIOD...WITH THE EXCEPTION OF SOME
PATCHY GROUND FOG DURING THE EARLY MORNING HOURS MAINLY AT THE
OUTLYING TERMINALS. WINDS WILL GENERALLY BE SOME SORT OF
NORTHWESTERLY DIRECTION THROUGH MIDDAY THOUGH THERE WILL LIKELY BE
VARIABILITY DUE TO THE LIGHT MAGNITUDE. WINDS SHOULD FAVOR A MORE
WESTERLY DIRECTION THIS AFTERNOON/EVENING. A LAKE BREEZE IS POSSIBLE
THIS AFTERNOON...THOUGH WEAK THERMAL CONTRAST AND OPPOSING FLOW
SHOULD KEEP IT FROM PUSHING IN ACROSS THE TERMINALS.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 14Z...

* HIGH WITH ALL FORECAST ELEMENTS.

KB

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

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.
SATURDAY...THUNDERSTORMS.
SUNDAY THROUGH MONDAY...VFR.

BMD

&&

.MARINE...
314 AM CDT

HIGH PRESSURE WILL BUILD ACROSS SOUTHERN LAKE MICHIGAN TODAY
ALLOWING WINDS TO DIMINISH...HOWEVER NORTHERN LAKE MICHIGAN WILL
SEE SOUTHWEST FLOW FRESHEN UP AHEAD OF THE NEXT COLD FRONT. THE
FRONT WILL SAG SOUTH ACROSS THE LAKE WEDNESDAY WITH HIGH PRESSURE
QUICKLY BUILDING IN BEHIND CAUSING A SHARP INCREASE IN WINDS
BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF THE NORTHEAST
WEDNESDAY EVENING. WINDS WILL VEER BACK AROUND TO THE SOUTHEAST
THURSDAY AND THURSDAY NIGHT DIMINISHING...THEN SOUTH TO SOUTHWEST
FRIDAY INCREASING BACK INTO THE 20 TO 25 KT RANGE...POSSIBLY 30 KT
AS BROAD LOW DEVELOPS OVER THE PLAINS AND CANADIAN PRAIRIES.

BMD

&&

.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 161155
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
655 AM CDT Tue Sep 16 2014

.SHORT TERM...(Today)
ISSUED AT 230 AM CDT TUE SEP 16 2014

Quiet weather expected overall today across central and southeast
Illinois. Canadian high pressure and its associated dry air mass will
continue to build into the area today, helping to scour out the low
clouds that currently reside across much of the forecast area. The
low clouds have been clearing slowly from the north as the high
builds in, and the latest trends suggest the clearing should reach
the I-70 corridor by 10 a.m. this morning. Once the skies clear,
mostly sunny skies should be the rule, as forecast soundings and CU
rule suggest diurnal cloud development should be minimal. The
possible exception to the clearing sticking, at least until sunrise,
is the potential for fog/stratus development. This development has
been patchy thus far upstream, and do not expect it to become too
widespread. Temperatures today, as they have been more often than
not lately, will be well below normal with highs mainly in the
mid-upper 60s.

&&

.LONG TERM...(Tonight through Monday)
ISSUED AT 230 AM CDT TUE SEP 16 2014

High pressure building southeast into the Great Lakes to dominate
our weather through Thursday. Latest model guidance continues to
indicate some sort of MCS type activity across Missouri and Kansas
Wednesday into Thursday, sliding along the edge of the upper ridge
that will slowly inch eastward into the Plains. However, the
persistent east/northeast flow over our area should keep this
precipitation at bay.

Significant shortwave will dig as it crosses the Rockies on Friday,
settling into the Mississippi Valley by Sunday morning. Have largely
kept the forecast dry through about midday Saturday, then quickly
increased the PoP`s from west to east during the afternoon and
evening hours, as the front arrives. One significant item of concern
is with the potential for heavy rain. The remnants of tropical
cyclone Odile over Baja California will be spreading into the Desert
Southwest over the next day or so. The latest GFS model continues to
show that a piece of energy and associated moisture from this system
will be drawn northeast into the northern wave, reaching central
Illinois after midnight Saturday night with the potential for a few
inches of rain. The ECMWF and Canadian models are not quite as
generous on this point, but do draw in some of the moisture into the
wave by Saturday morning and produce weekend rainfalls of up to 1.5
inches. Have increased PoP`s Saturday night to around 60% across
most of the forecast area, as confidence increases in the general
rainfall trend over the area. Continued the PoP`s on Sunday east of
I-55, although this should be winding down during the afternoon as
the front exits the area.

A large broad upper trough will persist over the Midwest early next
week in the wake of this system. Latest ECMWF model has
significantly backed down on the amount of cool air with this
system, with 850 mb temperatures on Monday now around +5C rather
than the -2C from the previous run. The GFS lags behind the ECMWF
with bringing the cooler conditions into the area. As a result, have
kept highs in the 70s on Sunday and Monday, with the coolest
conditions just beyond the current forecast period.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
ISSUED AT 655 AM CDT TUE SEP 16 2014

Generally quiet/VFR aviation weather conditions expected across
the central Illinois terminals through the 12Z TAF valid time.
The primary exception will be early this morning. A large area of
post-frontal IFR/MVFR cigs have dropped just south of the area,
but patchy stratus/fog have developed in its wake. While an hour
or two of IFR/MVFR conditions are possible over the next couple
hours, it should burn off quickly as the sun continues to rise.
Otherwise, cloud cover should be minimal. Patchy fog is possible
again late tonight, but a day of nearly full sun should keep
chances minimal. The arrival of the center of the surface high
should keep winds light/variable overall.

&&

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

$$

SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...BAK






000
FXUS63 KILX 161155
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
655 AM CDT Tue Sep 16 2014

.SHORT TERM...(Today)
ISSUED AT 230 AM CDT TUE SEP 16 2014

Quiet weather expected overall today across central and southeast
Illinois. Canadian high pressure and its associated dry air mass will
continue to build into the area today, helping to scour out the low
clouds that currently reside across much of the forecast area. The
low clouds have been clearing slowly from the north as the high
builds in, and the latest trends suggest the clearing should reach
the I-70 corridor by 10 a.m. this morning. Once the skies clear,
mostly sunny skies should be the rule, as forecast soundings and CU
rule suggest diurnal cloud development should be minimal. The
possible exception to the clearing sticking, at least until sunrise,
is the potential for fog/stratus development. This development has
been patchy thus far upstream, and do not expect it to become too
widespread. Temperatures today, as they have been more often than
not lately, will be well below normal with highs mainly in the
mid-upper 60s.

&&

.LONG TERM...(Tonight through Monday)
ISSUED AT 230 AM CDT TUE SEP 16 2014

High pressure building southeast into the Great Lakes to dominate
our weather through Thursday. Latest model guidance continues to
indicate some sort of MCS type activity across Missouri and Kansas
Wednesday into Thursday, sliding along the edge of the upper ridge
that will slowly inch eastward into the Plains. However, the
persistent east/northeast flow over our area should keep this
precipitation at bay.

Significant shortwave will dig as it crosses the Rockies on Friday,
settling into the Mississippi Valley by Sunday morning. Have largely
kept the forecast dry through about midday Saturday, then quickly
increased the PoP`s from west to east during the afternoon and
evening hours, as the front arrives. One significant item of concern
is with the potential for heavy rain. The remnants of tropical
cyclone Odile over Baja California will be spreading into the Desert
Southwest over the next day or so. The latest GFS model continues to
show that a piece of energy and associated moisture from this system
will be drawn northeast into the northern wave, reaching central
Illinois after midnight Saturday night with the potential for a few
inches of rain. The ECMWF and Canadian models are not quite as
generous on this point, but do draw in some of the moisture into the
wave by Saturday morning and produce weekend rainfalls of up to 1.5
inches. Have increased PoP`s Saturday night to around 60% across
most of the forecast area, as confidence increases in the general
rainfall trend over the area. Continued the PoP`s on Sunday east of
I-55, although this should be winding down during the afternoon as
the front exits the area.

A large broad upper trough will persist over the Midwest early next
week in the wake of this system. Latest ECMWF model has
significantly backed down on the amount of cool air with this
system, with 850 mb temperatures on Monday now around +5C rather
than the -2C from the previous run. The GFS lags behind the ECMWF
with bringing the cooler conditions into the area. As a result, have
kept highs in the 70s on Sunday and Monday, with the coolest
conditions just beyond the current forecast period.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
ISSUED AT 655 AM CDT TUE SEP 16 2014

Generally quiet/VFR aviation weather conditions expected across
the central Illinois terminals through the 12Z TAF valid time.
The primary exception will be early this morning. A large area of
post-frontal IFR/MVFR cigs have dropped just south of the area,
but patchy stratus/fog have developed in its wake. While an hour
or two of IFR/MVFR conditions are possible over the next couple
hours, it should burn off quickly as the sun continues to rise.
Otherwise, cloud cover should be minimal. Patchy fog is possible
again late tonight, but a day of nearly full sun should keep
chances minimal. The arrival of the center of the surface high
should keep winds light/variable overall.

&&

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

$$

SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...BAK







000
FXUS63 KLOT 161134
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
634 AM CDT TUE SEP 16 2014

.DISCUSSION...
320 AM CDT

SHOULD SEE "CHAMBER OF COMMERCE" TYPE WEATHER FOR THE REMAINDER OF
THE WORK WEEK WITH A GRADUAL WARMING TREND. A PERIOD WARM AND STORMY
WEATHER IS ON TAP FOR THE WEEKEND BEFORE THE TRANSITION TO THE NEXT
COOL DOWN TAKES PLACE TOWARD END OF THE FORECAST CYCLE.

COOL CANADIAN HIGH PRESSURE WILL SLOWLY MOVE EASTWARD ACROSS THE
REGION THIS WEEK BRINGING A CONTINUATION OF BELOW AVERAGE
TEMPERATURES. ON THE PLUS SIDE...LOOKS LIKE THERE WILL BE AMPLE
SUNSHINE AND LITTLE THREAT OF RAIN THROUGH AT LEAST THURSDAY NIGHT
AND PROBABLY THROUGH FRIDAY AS WELL. WARM FRONT IS PROGGED TO MOVE
ACROSS THE REGION FRIDAY...WITH GFS/ECMWF BRINGING IT THROUGH DRY
FOLLOWED BY A BRIEF WARM UP LATER FRIDAY AND ESPECIALLY SATURDAY AS
TRANSIENT UPPER RIDGE MOVES ACROSS THE REGION IN ADVANCE OF
APPROACHING TROUGH. LATEST GFS/ECMWF PROGGED 850MB/925MB TEMPS WOULD
SUPPORT HIGHS IN THE LOW TO MID 80S...BUT A LOT COULD CHANGE BETWEEN
NOW AND THEN SO KEPT HIGHS MORE CONSERVATIVE FOR NOW AND FIGURE WE
CAN TREND TOWARD 80S IN LATER FORECASTS IF LATER RUNS WARRANT DOING
SO.

LATER SATURDAY INTO SATURDAY NIGHT GFS AND ECMWF BOTH PHASE THE
REMNANTS OF EASTERN PACIFIC HURRICANE ODILE WITH A DEEPENING
NORTHERN STRONG SHORTWAVE RESULTING IN PERIOD OF POTENTIALLY HEAVY
SHOWERS AND THUNDERSTORMS ALONG A COLD FRONT. PRETTY COMMON FOR
SIGNIFICANT AMPLIFICATION OF LONG WAVE TROUGHS AS THEY PHASE WITH
REMNANT TROPICAL CYCLONES...AND GFS AND ECMWF BOTH SUGGEST THIS WILL
BE THE CASE EARLY NEXT WEEK WITH THE POTENTIAL FOR ANOTHER
SIGNIFICANT EARLY SEASON COLD SNAP.

IZZI

&&

.AVIATION...

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

* LAKE BREEZE POTENTIAL TUESDAY AFTERNOON.

BMD

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

HIGH PRESSURE WILL RESULT IN LIGHT WINDS AND PRIMARILY VFR
CONDITIONS THROUGH THE FORECAST PERIOD...WITH THE EXCEPTION OF SOME
PATCHY GROUND FOG DURING THE EARLY MORNING HOURS MAINLY AT THE
OUTLYING TERMINALS. WINDS WILL GENERALLY BE SOME SORT OF
NORTHWESTERLY DIRECTION THROUGH MIDDAY THOUGH THERE WILL LIKELY BE
VARIABILITY DUE TO THE LIGHT MAGNITUDE. WINDS SHOULD FAVOR A MORE
WESTERLY DIRECTION THIS AFTERNOON/EVENING. A LAKE BREEZE IS POSSIBLE
THIS AFTERNOON...THOUGH WEAK THERMAL CONTRAST AND OPPOSING FLOW
SHOULD KEEP IT FROM PUSHING IN ACROSS THE TERMINALS.

BMD


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

* HIGH CONFIDENCE IN WINDS LESS THAN 10 KT THROUGH THE PERIOD.
  MEDIUM CONFIDENCE IN WIND DIRECTION.
* HIGH CONFIDENCE IN OTHER FORECAST ELEMENTS.

BMD

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

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.
SATURDAY...THUNDERSTORMS.
SUNDAY THROUGH MONDAY...VFR.

BMD

&&

.MARINE...
314 AM CDT

HIGH PRESSURE WILL BUILD ACROSS SOUTHERN LAKE MICHIGAN TODAY
ALLOWING WINDS TO DIMINISH...HOWEVER NORTHERN LAKE MICHIGAN WILL
SEE SOUTHWEST FLOW FRESHEN UP AHEAD OF THE NEXT COLD FRONT. THE
FRONT WILL SAG SOUTH ACROSS THE LAKE WEDNESDAY WITH HIGH PRESSURE
QUICKLY BUILDING IN BEHIND CAUSING A SHARP INCREASE IN WINDS
BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF THE NORTHEAST
WEDNESDAY EVENING. WINDS WILL VEER BACK AROUND TO THE SOUTHEAST
THURSDAY AND THURSDAY NIGHT DIMINISHING...THEN SOUTH TO SOUTHWEST
FRIDAY INCREASING BACK INTO THE 20 TO 25 KT RANGE...POSSIBLY 30 KT
AS BROAD LOW DEVELOPS OVER THE PLAINS AND CANADIAN PRAIRIES.

BMD

&&

.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 161134
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
634 AM CDT TUE SEP 16 2014

.DISCUSSION...
320 AM CDT

SHOULD SEE "CHAMBER OF COMMERCE" TYPE WEATHER FOR THE REMAINDER OF
THE WORK WEEK WITH A GRADUAL WARMING TREND. A PERIOD WARM AND STORMY
WEATHER IS ON TAP FOR THE WEEKEND BEFORE THE TRANSITION TO THE NEXT
COOL DOWN TAKES PLACE TOWARD END OF THE FORECAST CYCLE.

COOL CANADIAN HIGH PRESSURE WILL SLOWLY MOVE EASTWARD ACROSS THE
REGION THIS WEEK BRINGING A CONTINUATION OF BELOW AVERAGE
TEMPERATURES. ON THE PLUS SIDE...LOOKS LIKE THERE WILL BE AMPLE
SUNSHINE AND LITTLE THREAT OF RAIN THROUGH AT LEAST THURSDAY NIGHT
AND PROBABLY THROUGH FRIDAY AS WELL. WARM FRONT IS PROGGED TO MOVE
ACROSS THE REGION FRIDAY...WITH GFS/ECMWF BRINGING IT THROUGH DRY
FOLLOWED BY A BRIEF WARM UP LATER FRIDAY AND ESPECIALLY SATURDAY AS
TRANSIENT UPPER RIDGE MOVES ACROSS THE REGION IN ADVANCE OF
APPROACHING TROUGH. LATEST GFS/ECMWF PROGGED 850MB/925MB TEMPS WOULD
SUPPORT HIGHS IN THE LOW TO MID 80S...BUT A LOT COULD CHANGE BETWEEN
NOW AND THEN SO KEPT HIGHS MORE CONSERVATIVE FOR NOW AND FIGURE WE
CAN TREND TOWARD 80S IN LATER FORECASTS IF LATER RUNS WARRANT DOING
SO.

LATER SATURDAY INTO SATURDAY NIGHT GFS AND ECMWF BOTH PHASE THE
REMNANTS OF EASTERN PACIFIC HURRICANE ODILE WITH A DEEPENING
NORTHERN STRONG SHORTWAVE RESULTING IN PERIOD OF POTENTIALLY HEAVY
SHOWERS AND THUNDERSTORMS ALONG A COLD FRONT. PRETTY COMMON FOR
SIGNIFICANT AMPLIFICATION OF LONG WAVE TROUGHS AS THEY PHASE WITH
REMNANT TROPICAL CYCLONES...AND GFS AND ECMWF BOTH SUGGEST THIS WILL
BE THE CASE EARLY NEXT WEEK WITH THE POTENTIAL FOR ANOTHER
SIGNIFICANT EARLY SEASON COLD SNAP.

IZZI

&&

.AVIATION...

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

* LAKE BREEZE POTENTIAL TUESDAY AFTERNOON.

BMD

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

HIGH PRESSURE WILL RESULT IN LIGHT WINDS AND PRIMARILY VFR
CONDITIONS THROUGH THE FORECAST PERIOD...WITH THE EXCEPTION OF SOME
PATCHY GROUND FOG DURING THE EARLY MORNING HOURS MAINLY AT THE
OUTLYING TERMINALS. WINDS WILL GENERALLY BE SOME SORT OF
NORTHWESTERLY DIRECTION THROUGH MIDDAY THOUGH THERE WILL LIKELY BE
VARIABILITY DUE TO THE LIGHT MAGNITUDE. WINDS SHOULD FAVOR A MORE
WESTERLY DIRECTION THIS AFTERNOON/EVENING. A LAKE BREEZE IS POSSIBLE
THIS AFTERNOON...THOUGH WEAK THERMAL CONTRAST AND OPPOSING FLOW
SHOULD KEEP IT FROM PUSHING IN ACROSS THE TERMINALS.

BMD


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

* HIGH CONFIDENCE IN WINDS LESS THAN 10 KT THROUGH THE PERIOD.
  MEDIUM CONFIDENCE IN WIND DIRECTION.
* HIGH CONFIDENCE IN OTHER FORECAST ELEMENTS.

BMD

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

WEDNESDAY NIGHT THROUGH FRIDAY...VFR.
SATURDAY...THUNDERSTORMS.
SUNDAY THROUGH MONDAY...VFR.

BMD

&&

.MARINE...
314 AM CDT

HIGH PRESSURE WILL BUILD ACROSS SOUTHERN LAKE MICHIGAN TODAY
ALLOWING WINDS TO DIMINISH...HOWEVER NORTHERN LAKE MICHIGAN WILL
SEE SOUTHWEST FLOW FRESHEN UP AHEAD OF THE NEXT COLD FRONT. THE
FRONT WILL SAG SOUTH ACROSS THE LAKE WEDNESDAY WITH HIGH PRESSURE
QUICKLY BUILDING IN BEHIND CAUSING A SHARP INCREASE IN WINDS
BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF THE NORTHEAST
WEDNESDAY EVENING. WINDS WILL VEER BACK AROUND TO THE SOUTHEAST
THURSDAY AND THURSDAY NIGHT DIMINISHING...THEN SOUTH TO SOUTHWEST
FRIDAY INCREASING BACK INTO THE 20 TO 25 KT RANGE...POSSIBLY 30 KT
AS BROAD LOW DEVELOPS OVER THE PLAINS AND CANADIAN PRAIRIES.

BMD

&&

.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 160859
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
359 AM CDT TUE SEP 16 2014

.DISCUSSION...
320 AM CDT

SHOULD SEE "CHAMBER OF COMMERCE" TYPE WEATHER FOR THE REMAINDER OF
THE WORK WEEK WITH A GRADUAL WARMING TREND. A PERIOD WARM AND STORMY
WEATHER IS ON TAP FOR THE WEEKEND BEFORE THE TRANSITION TO THE NEXT
COOL DOWN TAKES PLACE TOWARD END OF THE FORECAST CYCLE.

COOL CANADIAN HIGH PRESSURE WILL SLOWLY MOVE EASTWARD ACROSS THE
REGION THIS WEEK BRINGING A CONTINUATION OF BELOW AVERAGE
TEMPERATURES. ON THE PLUS SIDE...LOOKS LIKE THERE WILL BE AMPLE
SUNSHINE AND LITTLE THREAT OF RAIN THROUGH AT LEAST THURSDAY NIGHT
AND PROBABLY THROUGH FRIDAY AS WELL. WARM FRONT IS PROGGED TO MOVE
ACROSS THE REGION FRIDAY...WITH GFS/ECMWF BRINGING IT THROUGH DRY
FOLLOWED BY A BRIEF WARM UP LATER FRIDAY AND ESPECIALLY SATURDAY AS
TRANSIENT UPPER RIDGE MOVES ACROSS THE REGION IN ADVANCE OF
APPROACHING TROUGH. LATEST GFS/ECMWF PROGGED 850MB/925MB TEMPS WOULD
SUPPORT HIGHS IN THE LOW TO MID 80S...BUT A LOT COULD CHANGE BETWEEN
NOW AND THEN SO KEPT HIGHS MORE CONSERVATIVE FOR NOW AND FIGURE WE
CAN TREND TOWARD 80S IN LATER FORECASTS IF LATER RUNS WARRANT DOING
SO.

LATER SATURDAY INTO SATURDAY NIGHT GFS AND ECMWF BOTH PHASE THE
REMNANTS OF EASTERN PACIFIC HURRICANE ODILE WITH A DEEPENING
NORTHERN STRONG SHORTWAVE RESULTING IN PERIOD OF POTENTIALLY HEAVY
SHOWERS AND THUNDERSTORMS ALONG A COLD FRONT. PRETTY COMMON FOR
SIGNIFICANT AMPLIFICATION OF LONG WAVE TROUGHS AS THEY PHASE WITH
REMNANT TROPICAL CYCLONES...AND GFS AND ECMWF BOTH SUGGEST THIS WILL
BE THE CASE EARLY NEXT WEEK WITH THE POTENTIAL FOR ANOTHER
SIGNIFICANT EARLY SEASON COLD SNAP.

IZZI

&&

.AVIATION...

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

* FOG POTENTIAL EARLY TUESDAY.
* LAKE BREEZE POTENTIAL TUESDAY AFTERNOON.

BMD

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

HIGH PRESSURE WILL BUILD TO THE SOUTH OF THE TERMINALS TONIGHT
KEEPING WINDS VERY LIGHT AND ALLOWING CONDITIONS TO REMAIN
GENERALLY VFR OUTSIDE OF SOME FOG THIS MORNING. PATCHY FOG HAS
ALREADY DEVELOPED IN SOME AREAS AND WILL MOST LIKELY IMPACT
RFD/DPA WITH CONFIDENCE TOO LOW AT ORD/MDW/GYY AT THIS TIME TO
INCLUDE ANY MENTION IN THE TAF. WINDS WILL REMAIN LIGHT GENERALLY
4-7 KT THROUGH THE DAY TUESDAY OUT OF THE NORTHWEST THOUGH THERE
MAY BE SOME VARIABILITY IN DIRECTION DUE TO THE LIGHT MAGNITUDE.
WILL ALSO HAVE TO MONITOR A LAKE BREEZE MONDAY AFTERNOON. FOR NOW
EXPECT A LAKE BREEZE TO DEVELOP BUT STAY NEAR THE SHORE.

BMD

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

* LOW CONFIDENCE IN FOG IMPACTING TERMINALS.
* LOW CONFIDENCE THAT A LAKE BREEZE WILL PUSH FAR INLAND.
* HIGH CONFIDENCE IN VFR CONDITIONS AND WINDS LESS THAN 10 KT
  THROUGH PERIOD.

BMD

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

WEDNESDAY...VFR. LIGHT WEST WINDS. LAKE BREEZE POSSIBLE.

THURSDAY...VFR. EAST WINDS.

FRIDAY...VFR. BREEZY SOUTH WINDS.

SATURDAY...CHANCE TSRA. MVFR POSSIBLE. BREEZY SOUTHWEST WINDS.

SUNDAY...SLIGHT CHANCE TSRA. VFR. WEST WINDS.

MDB

&&

.MARINE...
314 AM CDT

HIGH PRESSURE WILL BUILD ACROSS SOUTHERN LAKE MICHIGAN TODAY
ALLOWING WINDS TO DIMINISH...HOWEVER NORTHERN LAKE MICHIGAN WILL
SEE SOUTHWEST FLOW FRESHEN UP AHEAD OF THE NEXT COLD FRONT. THE
FRONT WILL SAG SOUTH ACROSS THE LAKE WEDNESDAY WITH HIGH PRESSURE
QUICKLY BUILDING IN BEHIND CAUSING A SHARP INCREASE IN WINDS
BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF THE NORTHEAST
WEDNESDAY EVENING. WINDS WILL VEER BACK AROUND TO THE SOUTHEAST
THURSDAY AND THURSDAY NIGHT DIMINISHING...THEN SOUTH TO SOUTHWEST
FRIDAY INCREASING BACK INTO THE 20 TO 25 KT RANGE...POSSIBLY 30 KT
AS BROAD LOW DEVELOPS OVER THE PLAINS AND CANADIAN PRAIRIES.

BMD

&&

.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 160859
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
359 AM CDT TUE SEP 16 2014

.DISCUSSION...
320 AM CDT

SHOULD SEE "CHAMBER OF COMMERCE" TYPE WEATHER FOR THE REMAINDER OF
THE WORK WEEK WITH A GRADUAL WARMING TREND. A PERIOD WARM AND STORMY
WEATHER IS ON TAP FOR THE WEEKEND BEFORE THE TRANSITION TO THE NEXT
COOL DOWN TAKES PLACE TOWARD END OF THE FORECAST CYCLE.

COOL CANADIAN HIGH PRESSURE WILL SLOWLY MOVE EASTWARD ACROSS THE
REGION THIS WEEK BRINGING A CONTINUATION OF BELOW AVERAGE
TEMPERATURES. ON THE PLUS SIDE...LOOKS LIKE THERE WILL BE AMPLE
SUNSHINE AND LITTLE THREAT OF RAIN THROUGH AT LEAST THURSDAY NIGHT
AND PROBABLY THROUGH FRIDAY AS WELL. WARM FRONT IS PROGGED TO MOVE
ACROSS THE REGION FRIDAY...WITH GFS/ECMWF BRINGING IT THROUGH DRY
FOLLOWED BY A BRIEF WARM UP LATER FRIDAY AND ESPECIALLY SATURDAY AS
TRANSIENT UPPER RIDGE MOVES ACROSS THE REGION IN ADVANCE OF
APPROACHING TROUGH. LATEST GFS/ECMWF PROGGED 850MB/925MB TEMPS WOULD
SUPPORT HIGHS IN THE LOW TO MID 80S...BUT A LOT COULD CHANGE BETWEEN
NOW AND THEN SO KEPT HIGHS MORE CONSERVATIVE FOR NOW AND FIGURE WE
CAN TREND TOWARD 80S IN LATER FORECASTS IF LATER RUNS WARRANT DOING
SO.

LATER SATURDAY INTO SATURDAY NIGHT GFS AND ECMWF BOTH PHASE THE
REMNANTS OF EASTERN PACIFIC HURRICANE ODILE WITH A DEEPENING
NORTHERN STRONG SHORTWAVE RESULTING IN PERIOD OF POTENTIALLY HEAVY
SHOWERS AND THUNDERSTORMS ALONG A COLD FRONT. PRETTY COMMON FOR
SIGNIFICANT AMPLIFICATION OF LONG WAVE TROUGHS AS THEY PHASE WITH
REMNANT TROPICAL CYCLONES...AND GFS AND ECMWF BOTH SUGGEST THIS WILL
BE THE CASE EARLY NEXT WEEK WITH THE POTENTIAL FOR ANOTHER
SIGNIFICANT EARLY SEASON COLD SNAP.

IZZI

&&

.AVIATION...

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

* FOG POTENTIAL EARLY TUESDAY.
* LAKE BREEZE POTENTIAL TUESDAY AFTERNOON.

BMD

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

HIGH PRESSURE WILL BUILD TO THE SOUTH OF THE TERMINALS TONIGHT
KEEPING WINDS VERY LIGHT AND ALLOWING CONDITIONS TO REMAIN
GENERALLY VFR OUTSIDE OF SOME FOG THIS MORNING. PATCHY FOG HAS
ALREADY DEVELOPED IN SOME AREAS AND WILL MOST LIKELY IMPACT
RFD/DPA WITH CONFIDENCE TOO LOW AT ORD/MDW/GYY AT THIS TIME TO
INCLUDE ANY MENTION IN THE TAF. WINDS WILL REMAIN LIGHT GENERALLY
4-7 KT THROUGH THE DAY TUESDAY OUT OF THE NORTHWEST THOUGH THERE
MAY BE SOME VARIABILITY IN DIRECTION DUE TO THE LIGHT MAGNITUDE.
WILL ALSO HAVE TO MONITOR A LAKE BREEZE MONDAY AFTERNOON. FOR NOW
EXPECT A LAKE BREEZE TO DEVELOP BUT STAY NEAR THE SHORE.

BMD

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

* LOW CONFIDENCE IN FOG IMPACTING TERMINALS.
* LOW CONFIDENCE THAT A LAKE BREEZE WILL PUSH FAR INLAND.
* HIGH CONFIDENCE IN VFR CONDITIONS AND WINDS LESS THAN 10 KT
  THROUGH PERIOD.

BMD

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

WEDNESDAY...VFR. LIGHT WEST WINDS. LAKE BREEZE POSSIBLE.

THURSDAY...VFR. EAST WINDS.

FRIDAY...VFR. BREEZY SOUTH WINDS.

SATURDAY...CHANCE TSRA. MVFR POSSIBLE. BREEZY SOUTHWEST WINDS.

SUNDAY...SLIGHT CHANCE TSRA. VFR. WEST WINDS.

MDB

&&

.MARINE...
314 AM CDT

HIGH PRESSURE WILL BUILD ACROSS SOUTHERN LAKE MICHIGAN TODAY
ALLOWING WINDS TO DIMINISH...HOWEVER NORTHERN LAKE MICHIGAN WILL
SEE SOUTHWEST FLOW FRESHEN UP AHEAD OF THE NEXT COLD FRONT. THE
FRONT WILL SAG SOUTH ACROSS THE LAKE WEDNESDAY WITH HIGH PRESSURE
QUICKLY BUILDING IN BEHIND CAUSING A SHARP INCREASE IN WINDS
BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF THE NORTHEAST
WEDNESDAY EVENING. WINDS WILL VEER BACK AROUND TO THE SOUTHEAST
THURSDAY AND THURSDAY NIGHT DIMINISHING...THEN SOUTH TO SOUTHWEST
FRIDAY INCREASING BACK INTO THE 20 TO 25 KT RANGE...POSSIBLY 30 KT
AS BROAD LOW DEVELOPS OVER THE PLAINS AND CANADIAN PRAIRIES.

BMD

&&

.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 160859
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
359 AM CDT TUE SEP 16 2014

.DISCUSSION...
320 AM CDT

SHOULD SEE "CHAMBER OF COMMERCE" TYPE WEATHER FOR THE REMAINDER OF
THE WORK WEEK WITH A GRADUAL WARMING TREND. A PERIOD WARM AND STORMY
WEATHER IS ON TAP FOR THE WEEKEND BEFORE THE TRANSITION TO THE NEXT
COOL DOWN TAKES PLACE TOWARD END OF THE FORECAST CYCLE.

COOL CANADIAN HIGH PRESSURE WILL SLOWLY MOVE EASTWARD ACROSS THE
REGION THIS WEEK BRINGING A CONTINUATION OF BELOW AVERAGE
TEMPERATURES. ON THE PLUS SIDE...LOOKS LIKE THERE WILL BE AMPLE
SUNSHINE AND LITTLE THREAT OF RAIN THROUGH AT LEAST THURSDAY NIGHT
AND PROBABLY THROUGH FRIDAY AS WELL. WARM FRONT IS PROGGED TO MOVE
ACROSS THE REGION FRIDAY...WITH GFS/ECMWF BRINGING IT THROUGH DRY
FOLLOWED BY A BRIEF WARM UP LATER FRIDAY AND ESPECIALLY SATURDAY AS
TRANSIENT UPPER RIDGE MOVES ACROSS THE REGION IN ADVANCE OF
APPROACHING TROUGH. LATEST GFS/ECMWF PROGGED 850MB/925MB TEMPS WOULD
SUPPORT HIGHS IN THE LOW TO MID 80S...BUT A LOT COULD CHANGE BETWEEN
NOW AND THEN SO KEPT HIGHS MORE CONSERVATIVE FOR NOW AND FIGURE WE
CAN TREND TOWARD 80S IN LATER FORECASTS IF LATER RUNS WARRANT DOING
SO.

LATER SATURDAY INTO SATURDAY NIGHT GFS AND ECMWF BOTH PHASE THE
REMNANTS OF EASTERN PACIFIC HURRICANE ODILE WITH A DEEPENING
NORTHERN STRONG SHORTWAVE RESULTING IN PERIOD OF POTENTIALLY HEAVY
SHOWERS AND THUNDERSTORMS ALONG A COLD FRONT. PRETTY COMMON FOR
SIGNIFICANT AMPLIFICATION OF LONG WAVE TROUGHS AS THEY PHASE WITH
REMNANT TROPICAL CYCLONES...AND GFS AND ECMWF BOTH SUGGEST THIS WILL
BE THE CASE EARLY NEXT WEEK WITH THE POTENTIAL FOR ANOTHER
SIGNIFICANT EARLY SEASON COLD SNAP.

IZZI

&&

.AVIATION...

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

* FOG POTENTIAL EARLY TUESDAY.
* LAKE BREEZE POTENTIAL TUESDAY AFTERNOON.

BMD

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

HIGH PRESSURE WILL BUILD TO THE SOUTH OF THE TERMINALS TONIGHT
KEEPING WINDS VERY LIGHT AND ALLOWING CONDITIONS TO REMAIN
GENERALLY VFR OUTSIDE OF SOME FOG THIS MORNING. PATCHY FOG HAS
ALREADY DEVELOPED IN SOME AREAS AND WILL MOST LIKELY IMPACT
RFD/DPA WITH CONFIDENCE TOO LOW AT ORD/MDW/GYY AT THIS TIME TO
INCLUDE ANY MENTION IN THE TAF. WINDS WILL REMAIN LIGHT GENERALLY
4-7 KT THROUGH THE DAY TUESDAY OUT OF THE NORTHWEST THOUGH THERE
MAY BE SOME VARIABILITY IN DIRECTION DUE TO THE LIGHT MAGNITUDE.
WILL ALSO HAVE TO MONITOR A LAKE BREEZE MONDAY AFTERNOON. FOR NOW
EXPECT A LAKE BREEZE TO DEVELOP BUT STAY NEAR THE SHORE.

BMD

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

* LOW CONFIDENCE IN FOG IMPACTING TERMINALS.
* LOW CONFIDENCE THAT A LAKE BREEZE WILL PUSH FAR INLAND.
* HIGH CONFIDENCE IN VFR CONDITIONS AND WINDS LESS THAN 10 KT
  THROUGH PERIOD.

BMD

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

WEDNESDAY...VFR. LIGHT WEST WINDS. LAKE BREEZE POSSIBLE.

THURSDAY...VFR. EAST WINDS.

FRIDAY...VFR. BREEZY SOUTH WINDS.

SATURDAY...CHANCE TSRA. MVFR POSSIBLE. BREEZY SOUTHWEST WINDS.

SUNDAY...SLIGHT CHANCE TSRA. VFR. WEST WINDS.

MDB

&&

.MARINE...
314 AM CDT

HIGH PRESSURE WILL BUILD ACROSS SOUTHERN LAKE MICHIGAN TODAY
ALLOWING WINDS TO DIMINISH...HOWEVER NORTHERN LAKE MICHIGAN WILL
SEE SOUTHWEST FLOW FRESHEN UP AHEAD OF THE NEXT COLD FRONT. THE
FRONT WILL SAG SOUTH ACROSS THE LAKE WEDNESDAY WITH HIGH PRESSURE
QUICKLY BUILDING IN BEHIND CAUSING A SHARP INCREASE IN WINDS
BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF THE NORTHEAST
WEDNESDAY EVENING. WINDS WILL VEER BACK AROUND TO THE SOUTHEAST
THURSDAY AND THURSDAY NIGHT DIMINISHING...THEN SOUTH TO SOUTHWEST
FRIDAY INCREASING BACK INTO THE 20 TO 25 KT RANGE...POSSIBLY 30 KT
AS BROAD LOW DEVELOPS OVER THE PLAINS AND CANADIAN PRAIRIES.

BMD

&&

.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 160859
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
359 AM CDT TUE SEP 16 2014

.DISCUSSION...
320 AM CDT

SHOULD SEE "CHAMBER OF COMMERCE" TYPE WEATHER FOR THE REMAINDER OF
THE WORK WEEK WITH A GRADUAL WARMING TREND. A PERIOD WARM AND STORMY
WEATHER IS ON TAP FOR THE WEEKEND BEFORE THE TRANSITION TO THE NEXT
COOL DOWN TAKES PLACE TOWARD END OF THE FORECAST CYCLE.

COOL CANADIAN HIGH PRESSURE WILL SLOWLY MOVE EASTWARD ACROSS THE
REGION THIS WEEK BRINGING A CONTINUATION OF BELOW AVERAGE
TEMPERATURES. ON THE PLUS SIDE...LOOKS LIKE THERE WILL BE AMPLE
SUNSHINE AND LITTLE THREAT OF RAIN THROUGH AT LEAST THURSDAY NIGHT
AND PROBABLY THROUGH FRIDAY AS WELL. WARM FRONT IS PROGGED TO MOVE
ACROSS THE REGION FRIDAY...WITH GFS/ECMWF BRINGING IT THROUGH DRY
FOLLOWED BY A BRIEF WARM UP LATER FRIDAY AND ESPECIALLY SATURDAY AS
TRANSIENT UPPER RIDGE MOVES ACROSS THE REGION IN ADVANCE OF
APPROACHING TROUGH. LATEST GFS/ECMWF PROGGED 850MB/925MB TEMPS WOULD
SUPPORT HIGHS IN THE LOW TO MID 80S...BUT A LOT COULD CHANGE BETWEEN
NOW AND THEN SO KEPT HIGHS MORE CONSERVATIVE FOR NOW AND FIGURE WE
CAN TREND TOWARD 80S IN LATER FORECASTS IF LATER RUNS WARRANT DOING
SO.

LATER SATURDAY INTO SATURDAY NIGHT GFS AND ECMWF BOTH PHASE THE
REMNANTS OF EASTERN PACIFIC HURRICANE ODILE WITH A DEEPENING
NORTHERN STRONG SHORTWAVE RESULTING IN PERIOD OF POTENTIALLY HEAVY
SHOWERS AND THUNDERSTORMS ALONG A COLD FRONT. PRETTY COMMON FOR
SIGNIFICANT AMPLIFICATION OF LONG WAVE TROUGHS AS THEY PHASE WITH
REMNANT TROPICAL CYCLONES...AND GFS AND ECMWF BOTH SUGGEST THIS WILL
BE THE CASE EARLY NEXT WEEK WITH THE POTENTIAL FOR ANOTHER
SIGNIFICANT EARLY SEASON COLD SNAP.

IZZI

&&

.AVIATION...

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

* FOG POTENTIAL EARLY TUESDAY.
* LAKE BREEZE POTENTIAL TUESDAY AFTERNOON.

BMD

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

HIGH PRESSURE WILL BUILD TO THE SOUTH OF THE TERMINALS TONIGHT
KEEPING WINDS VERY LIGHT AND ALLOWING CONDITIONS TO REMAIN
GENERALLY VFR OUTSIDE OF SOME FOG THIS MORNING. PATCHY FOG HAS
ALREADY DEVELOPED IN SOME AREAS AND WILL MOST LIKELY IMPACT
RFD/DPA WITH CONFIDENCE TOO LOW AT ORD/MDW/GYY AT THIS TIME TO
INCLUDE ANY MENTION IN THE TAF. WINDS WILL REMAIN LIGHT GENERALLY
4-7 KT THROUGH THE DAY TUESDAY OUT OF THE NORTHWEST THOUGH THERE
MAY BE SOME VARIABILITY IN DIRECTION DUE TO THE LIGHT MAGNITUDE.
WILL ALSO HAVE TO MONITOR A LAKE BREEZE MONDAY AFTERNOON. FOR NOW
EXPECT A LAKE BREEZE TO DEVELOP BUT STAY NEAR THE SHORE.

BMD

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

* LOW CONFIDENCE IN FOG IMPACTING TERMINALS.
* LOW CONFIDENCE THAT A LAKE BREEZE WILL PUSH FAR INLAND.
* HIGH CONFIDENCE IN VFR CONDITIONS AND WINDS LESS THAN 10 KT
  THROUGH PERIOD.

BMD

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

WEDNESDAY...VFR. LIGHT WEST WINDS. LAKE BREEZE POSSIBLE.

THURSDAY...VFR. EAST WINDS.

FRIDAY...VFR. BREEZY SOUTH WINDS.

SATURDAY...CHANCE TSRA. MVFR POSSIBLE. BREEZY SOUTHWEST WINDS.

SUNDAY...SLIGHT CHANCE TSRA. VFR. WEST WINDS.

MDB

&&

.MARINE...
314 AM CDT

HIGH PRESSURE WILL BUILD ACROSS SOUTHERN LAKE MICHIGAN TODAY
ALLOWING WINDS TO DIMINISH...HOWEVER NORTHERN LAKE MICHIGAN WILL
SEE SOUTHWEST FLOW FRESHEN UP AHEAD OF THE NEXT COLD FRONT. THE
FRONT WILL SAG SOUTH ACROSS THE LAKE WEDNESDAY WITH HIGH PRESSURE
QUICKLY BUILDING IN BEHIND CAUSING A SHARP INCREASE IN WINDS
BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF THE NORTHEAST
WEDNESDAY EVENING. WINDS WILL VEER BACK AROUND TO THE SOUTHEAST
THURSDAY AND THURSDAY NIGHT DIMINISHING...THEN SOUTH TO SOUTHWEST
FRIDAY INCREASING BACK INTO THE 20 TO 25 KT RANGE...POSSIBLY 30 KT
AS BROAD LOW DEVELOPS OVER THE PLAINS AND CANADIAN PRAIRIES.

BMD

&&

.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 160820
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
320 AM CDT TUE SEP 16 2014

.DISCUSSION...
320 AM CDT

SHOULD SEE "CHAMBER OF COMMERCE" TYPE WEATHER FOR THE REMAINDER OF
THE WORK WEEK WITH A GRADUAL WARMING TREND. A PERIOD WARM AND STORMY
WEATHER IS ON TAP FOR THE WEEKEND BEFORE THE TRANSITION TO THE NEXT
COOL DOWN TAKES PLACE TOWARD END OF THE FORECAST CYCLE.

COOL CANADIAN HIGH PRESSURE WILL SLOWLY MOVE EASTWARD ACROSS THE
REGION THIS WEEK BRINGING A CONTINUATION OF BELOW AVERAGE
TEMPERATURES. ON THE PLUS SIDE...LOOKS LIKE THERE WILL BE AMPLE
SUNSHINE AND LITTLE THREAT OF RAIN THROUGH AT LEAST THURSDAY NIGHT
AND PROBABLY THROUGH FRIDAY AS WELL. WARM FRONT IS PROGGED TO MOVE
ACROSS THE REGION FRIDAY...WITH GFS/ECMWF BRINGING IT THROUGH DRY
FOLLOWED BY A BRIEF WARM UP LATER FRIDAY AND ESPECIALLY SATURDAY AS
TRANSIENT UPPER RIDGE MOVES ACROSS THE REGION IN ADVANCE OF
APPROACHING TROUGH. LATEST GFS/ECMWF PROGGED 850MB/925MB TEMPS WOULD
SUPPORT HIGHS IN THE LOW TO MID 80S...BUT A LOT COULD CHANGE BETWEEN
NOW AND THEN SO KEPT HIGHS MORE CONSERVATIVE FOR NOW AND FIGURE WE
CAN TREND TOWARD 80S IN LATER FORECASTS IF LATER RUNS WARRANT DOING
SO.

LATER SATURDAY INTO SATURDAY NIGHT GFS AND ECMWF BOTH PHASE THE
REMNANTS OF EASTERN PACIFIC HURRICANE ODILE WITH A DEEPENING
NORTHERN STRONG SHORTWAVE RESULTING IN PERIOD OF POTENTIALLY HEAVY
SHOWERS AND THUNDERSTORMS ALONG A COLD FRONT. PRETTY COMMON FOR
SIGNIFICANT AMPLIFICATION OF LONG WAVE TROUGHS AS THEY PHASE WITH
REMNANT TROPICAL CYCLONES...AND GFS AND ECMWF BOTH SUGGEST THIS WILL
BE THE CASE EARLY NEXT WEEK WITH THE POTENTIAL FOR ANOTHER
SIGNIFICANT EARLY SEASON COLD SNAP.

IZZI

&&

.AVIATION...

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

* FOG POTENTIAL EARLY TUESDAY.
* LAKE BREEZE POTENTIAL TUESDAY AFTERNOON.

BMD

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

HIGH PRESSURE WILL BUILD TO THE SOUTH OF THE TERMINALS TONIGHT
KEEPING WINDS VERY LIGHT AND ALLOWING CONDITIONS TO REMAIN
GENERALLY VFR OUTSIDE OF SOME FOG THIS MORNING. PATCHY FOG HAS
ALREADY DEVELOPED IN SOME AREAS AND WILL MOST LIKELY IMPACT
RFD/DPA WITH CONFIDENCE TOO LOW AT ORD/MDW/GYY AT THIS TIME TO
INCLUDE ANY MENTION IN THE TAF. WINDS WILL REMAIN LIGHT GENERALLY
4-7 KT THROUGH THE DAY TUESDAY OUT OF THE NORTHWEST THOUGH THERE
MAY BE SOME VARIABILITY IN DIRECTION DUE TO THE LIGHT MAGNITUDE.
WILL ALSO HAVE TO MONITOR A LAKE BREEZE MONDAY AFTERNOON. FOR NOW
EXPECT A LAKE BREEZE TO DEVELOP BUT STAY NEAR THE SHORE.

BMD

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

* LOW CONFIDENCE IN FOG IMPACTING TERMINALS.
* LOW CONFIDENCE THAT A LAKE BREEZE WILL PUSH FAR INLAND.
* HIGH CONFIDENCE IN VFR CONDITIONS AND WINDS LESS THAN 10 KT
  THROUGH PERIOD.

BMD

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

WEDNESDAY...VFR. LIGHT WEST WINDS. LAKE BREEZE POSSIBLE.

THURSDAY...VFR. EAST WINDS.

FRIDAY...VFR. BREEZY SOUTH WINDS.

SATURDAY...CHANCE TSRA. MVFR POSSIBLE. BREEZY SOUTHWEST WINDS.

SUNDAY...SLIGHT CHANCE TSRA. VFR. WEST WINDS.

MDB

&&

.MARINE...
314 AM CDT

HIGH PRESSURE WILL BUILD ACROSS SOUTHERN LAKE MICHIGAN TODAY
ALLOWING WINDS TO DIMINISH...HOWEVER NORTHERN LAKE MICHIGAN WILL
SEE SOUTHWEST FLOW FRESHEN UP AHEAD OF THE NEXT COLD FRONT. THE
FRONT WILL SAG SOUTH ACROSS THE LAKE WEDNESDAY WITH HIGH PRESSURE
QUICKLY BUILDING IN BEHIND CAUSING A SHARP INCREASE IN WINDS
BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF THE NORTHEAST
WEDNESDAY EVENING. WINDS WILL VEER BACK AROUND TO THE SOUTHEAST
THURSDAY AND THURSDAY NIGHT DIMINISHING...THEN SOUTH TO SOUTHWEST
FRIDAY INCREASING BACK INTO THE 20 TO 25 KT RANGE...POSSIBLY 30 KT
AS BROAD LOW DEVELOPS OVER THE PLAINS AND CANADIAN PRAIRIES.

BMD

&&

.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 160820
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
320 AM CDT TUE SEP 16 2014

.DISCUSSION...
320 AM CDT

SHOULD SEE "CHAMBER OF COMMERCE" TYPE WEATHER FOR THE REMAINDER OF
THE WORK WEEK WITH A GRADUAL WARMING TREND. A PERIOD WARM AND STORMY
WEATHER IS ON TAP FOR THE WEEKEND BEFORE THE TRANSITION TO THE NEXT
COOL DOWN TAKES PLACE TOWARD END OF THE FORECAST CYCLE.

COOL CANADIAN HIGH PRESSURE WILL SLOWLY MOVE EASTWARD ACROSS THE
REGION THIS WEEK BRINGING A CONTINUATION OF BELOW AVERAGE
TEMPERATURES. ON THE PLUS SIDE...LOOKS LIKE THERE WILL BE AMPLE
SUNSHINE AND LITTLE THREAT OF RAIN THROUGH AT LEAST THURSDAY NIGHT
AND PROBABLY THROUGH FRIDAY AS WELL. WARM FRONT IS PROGGED TO MOVE
ACROSS THE REGION FRIDAY...WITH GFS/ECMWF BRINGING IT THROUGH DRY
FOLLOWED BY A BRIEF WARM UP LATER FRIDAY AND ESPECIALLY SATURDAY AS
TRANSIENT UPPER RIDGE MOVES ACROSS THE REGION IN ADVANCE OF
APPROACHING TROUGH. LATEST GFS/ECMWF PROGGED 850MB/925MB TEMPS WOULD
SUPPORT HIGHS IN THE LOW TO MID 80S...BUT A LOT COULD CHANGE BETWEEN
NOW AND THEN SO KEPT HIGHS MORE CONSERVATIVE FOR NOW AND FIGURE WE
CAN TREND TOWARD 80S IN LATER FORECASTS IF LATER RUNS WARRANT DOING
SO.

LATER SATURDAY INTO SATURDAY NIGHT GFS AND ECMWF BOTH PHASE THE
REMNANTS OF EASTERN PACIFIC HURRICANE ODILE WITH A DEEPENING
NORTHERN STRONG SHORTWAVE RESULTING IN PERIOD OF POTENTIALLY HEAVY
SHOWERS AND THUNDERSTORMS ALONG A COLD FRONT. PRETTY COMMON FOR
SIGNIFICANT AMPLIFICATION OF LONG WAVE TROUGHS AS THEY PHASE WITH
REMNANT TROPICAL CYCLONES...AND GFS AND ECMWF BOTH SUGGEST THIS WILL
BE THE CASE EARLY NEXT WEEK WITH THE POTENTIAL FOR ANOTHER
SIGNIFICANT EARLY SEASON COLD SNAP.

IZZI

&&

.AVIATION...

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

* FOG POTENTIAL EARLY TUESDAY.
* LAKE BREEZE POTENTIAL TUESDAY AFTERNOON.

BMD

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

HIGH PRESSURE WILL BUILD TO THE SOUTH OF THE TERMINALS TONIGHT
KEEPING WINDS VERY LIGHT AND ALLOWING CONDITIONS TO REMAIN
GENERALLY VFR OUTSIDE OF SOME FOG THIS MORNING. PATCHY FOG HAS
ALREADY DEVELOPED IN SOME AREAS AND WILL MOST LIKELY IMPACT
RFD/DPA WITH CONFIDENCE TOO LOW AT ORD/MDW/GYY AT THIS TIME TO
INCLUDE ANY MENTION IN THE TAF. WINDS WILL REMAIN LIGHT GENERALLY
4-7 KT THROUGH THE DAY TUESDAY OUT OF THE NORTHWEST THOUGH THERE
MAY BE SOME VARIABILITY IN DIRECTION DUE TO THE LIGHT MAGNITUDE.
WILL ALSO HAVE TO MONITOR A LAKE BREEZE MONDAY AFTERNOON. FOR NOW
EXPECT A LAKE BREEZE TO DEVELOP BUT STAY NEAR THE SHORE.

BMD

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

* LOW CONFIDENCE IN FOG IMPACTING TERMINALS.
* LOW CONFIDENCE THAT A LAKE BREEZE WILL PUSH FAR INLAND.
* HIGH CONFIDENCE IN VFR CONDITIONS AND WINDS LESS THAN 10 KT
  THROUGH PERIOD.

BMD

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

WEDNESDAY...VFR. LIGHT WEST WINDS. LAKE BREEZE POSSIBLE.

THURSDAY...VFR. EAST WINDS.

FRIDAY...VFR. BREEZY SOUTH WINDS.

SATURDAY...CHANCE TSRA. MVFR POSSIBLE. BREEZY SOUTHWEST WINDS.

SUNDAY...SLIGHT CHANCE TSRA. VFR. WEST WINDS.

MDB

&&

.MARINE...
314 AM CDT

HIGH PRESSURE WILL BUILD ACROSS SOUTHERN LAKE MICHIGAN TODAY
ALLOWING WINDS TO DIMINISH...HOWEVER NORTHERN LAKE MICHIGAN WILL
SEE SOUTHWEST FLOW FRESHEN UP AHEAD OF THE NEXT COLD FRONT. THE
FRONT WILL SAG SOUTH ACROSS THE LAKE WEDNESDAY WITH HIGH PRESSURE
QUICKLY BUILDING IN BEHIND CAUSING A SHARP INCREASE IN WINDS
BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF THE NORTHEAST
WEDNESDAY EVENING. WINDS WILL VEER BACK AROUND TO THE SOUTHEAST
THURSDAY AND THURSDAY NIGHT DIMINISHING...THEN SOUTH TO SOUTHWEST
FRIDAY INCREASING BACK INTO THE 20 TO 25 KT RANGE...POSSIBLY 30 KT
AS BROAD LOW DEVELOPS OVER THE PLAINS AND CANADIAN PRAIRIES.

BMD

&&

.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 160820
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
320 AM CDT TUE SEP 16 2014

.DISCUSSION...
320 AM CDT

SHOULD SEE "CHAMBER OF COMMERCE" TYPE WEATHER FOR THE REMAINDER OF
THE WORK WEEK WITH A GRADUAL WARMING TREND. A PERIOD WARM AND STORMY
WEATHER IS ON TAP FOR THE WEEKEND BEFORE THE TRANSITION TO THE NEXT
COOL DOWN TAKES PLACE TOWARD END OF THE FORECAST CYCLE.

COOL CANADIAN HIGH PRESSURE WILL SLOWLY MOVE EASTWARD ACROSS THE
REGION THIS WEEK BRINGING A CONTINUATION OF BELOW AVERAGE
TEMPERATURES. ON THE PLUS SIDE...LOOKS LIKE THERE WILL BE AMPLE
SUNSHINE AND LITTLE THREAT OF RAIN THROUGH AT LEAST THURSDAY NIGHT
AND PROBABLY THROUGH FRIDAY AS WELL. WARM FRONT IS PROGGED TO MOVE
ACROSS THE REGION FRIDAY...WITH GFS/ECMWF BRINGING IT THROUGH DRY
FOLLOWED BY A BRIEF WARM UP LATER FRIDAY AND ESPECIALLY SATURDAY AS
TRANSIENT UPPER RIDGE MOVES ACROSS THE REGION IN ADVANCE OF
APPROACHING TROUGH. LATEST GFS/ECMWF PROGGED 850MB/925MB TEMPS WOULD
SUPPORT HIGHS IN THE LOW TO MID 80S...BUT A LOT COULD CHANGE BETWEEN
NOW AND THEN SO KEPT HIGHS MORE CONSERVATIVE FOR NOW AND FIGURE WE
CAN TREND TOWARD 80S IN LATER FORECASTS IF LATER RUNS WARRANT DOING
SO.

LATER SATURDAY INTO SATURDAY NIGHT GFS AND ECMWF BOTH PHASE THE
REMNANTS OF EASTERN PACIFIC HURRICANE ODILE WITH A DEEPENING
NORTHERN STRONG SHORTWAVE RESULTING IN PERIOD OF POTENTIALLY HEAVY
SHOWERS AND THUNDERSTORMS ALONG A COLD FRONT. PRETTY COMMON FOR
SIGNIFICANT AMPLIFICATION OF LONG WAVE TROUGHS AS THEY PHASE WITH
REMNANT TROPICAL CYCLONES...AND GFS AND ECMWF BOTH SUGGEST THIS WILL
BE THE CASE EARLY NEXT WEEK WITH THE POTENTIAL FOR ANOTHER
SIGNIFICANT EARLY SEASON COLD SNAP.

IZZI

&&

.AVIATION...

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

* FOG POTENTIAL EARLY TUESDAY.
* LAKE BREEZE POTENTIAL TUESDAY AFTERNOON.

BMD

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

HIGH PRESSURE WILL BUILD TO THE SOUTH OF THE TERMINALS TONIGHT
KEEPING WINDS VERY LIGHT AND ALLOWING CONDITIONS TO REMAIN
GENERALLY VFR OUTSIDE OF SOME FOG THIS MORNING. PATCHY FOG HAS
ALREADY DEVELOPED IN SOME AREAS AND WILL MOST LIKELY IMPACT
RFD/DPA WITH CONFIDENCE TOO LOW AT ORD/MDW/GYY AT THIS TIME TO
INCLUDE ANY MENTION IN THE TAF. WINDS WILL REMAIN LIGHT GENERALLY
4-7 KT THROUGH THE DAY TUESDAY OUT OF THE NORTHWEST THOUGH THERE
MAY BE SOME VARIABILITY IN DIRECTION DUE TO THE LIGHT MAGNITUDE.
WILL ALSO HAVE TO MONITOR A LAKE BREEZE MONDAY AFTERNOON. FOR NOW
EXPECT A LAKE BREEZE TO DEVELOP BUT STAY NEAR THE SHORE.

BMD

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

* LOW CONFIDENCE IN FOG IMPACTING TERMINALS.
* LOW CONFIDENCE THAT A LAKE BREEZE WILL PUSH FAR INLAND.
* HIGH CONFIDENCE IN VFR CONDITIONS AND WINDS LESS THAN 10 KT
  THROUGH PERIOD.

BMD

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

WEDNESDAY...VFR. LIGHT WEST WINDS. LAKE BREEZE POSSIBLE.

THURSDAY...VFR. EAST WINDS.

FRIDAY...VFR. BREEZY SOUTH WINDS.

SATURDAY...CHANCE TSRA. MVFR POSSIBLE. BREEZY SOUTHWEST WINDS.

SUNDAY...SLIGHT CHANCE TSRA. VFR. WEST WINDS.

MDB

&&

.MARINE...
314 AM CDT

HIGH PRESSURE WILL BUILD ACROSS SOUTHERN LAKE MICHIGAN TODAY
ALLOWING WINDS TO DIMINISH...HOWEVER NORTHERN LAKE MICHIGAN WILL
SEE SOUTHWEST FLOW FRESHEN UP AHEAD OF THE NEXT COLD FRONT. THE
FRONT WILL SAG SOUTH ACROSS THE LAKE WEDNESDAY WITH HIGH PRESSURE
QUICKLY BUILDING IN BEHIND CAUSING A SHARP INCREASE IN WINDS
BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF THE NORTHEAST
WEDNESDAY EVENING. WINDS WILL VEER BACK AROUND TO THE SOUTHEAST
THURSDAY AND THURSDAY NIGHT DIMINISHING...THEN SOUTH TO SOUTHWEST
FRIDAY INCREASING BACK INTO THE 20 TO 25 KT RANGE...POSSIBLY 30 KT
AS BROAD LOW DEVELOPS OVER THE PLAINS AND CANADIAN PRAIRIES.

BMD

&&

.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 160820
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
320 AM CDT TUE SEP 16 2014

.DISCUSSION...
320 AM CDT

SHOULD SEE "CHAMBER OF COMMERCE" TYPE WEATHER FOR THE REMAINDER OF
THE WORK WEEK WITH A GRADUAL WARMING TREND. A PERIOD WARM AND STORMY
WEATHER IS ON TAP FOR THE WEEKEND BEFORE THE TRANSITION TO THE NEXT
COOL DOWN TAKES PLACE TOWARD END OF THE FORECAST CYCLE.

COOL CANADIAN HIGH PRESSURE WILL SLOWLY MOVE EASTWARD ACROSS THE
REGION THIS WEEK BRINGING A CONTINUATION OF BELOW AVERAGE
TEMPERATURES. ON THE PLUS SIDE...LOOKS LIKE THERE WILL BE AMPLE
SUNSHINE AND LITTLE THREAT OF RAIN THROUGH AT LEAST THURSDAY NIGHT
AND PROBABLY THROUGH FRIDAY AS WELL. WARM FRONT IS PROGGED TO MOVE
ACROSS THE REGION FRIDAY...WITH GFS/ECMWF BRINGING IT THROUGH DRY
FOLLOWED BY A BRIEF WARM UP LATER FRIDAY AND ESPECIALLY SATURDAY AS
TRANSIENT UPPER RIDGE MOVES ACROSS THE REGION IN ADVANCE OF
APPROACHING TROUGH. LATEST GFS/ECMWF PROGGED 850MB/925MB TEMPS WOULD
SUPPORT HIGHS IN THE LOW TO MID 80S...BUT A LOT COULD CHANGE BETWEEN
NOW AND THEN SO KEPT HIGHS MORE CONSERVATIVE FOR NOW AND FIGURE WE
CAN TREND TOWARD 80S IN LATER FORECASTS IF LATER RUNS WARRANT DOING
SO.

LATER SATURDAY INTO SATURDAY NIGHT GFS AND ECMWF BOTH PHASE THE
REMNANTS OF EASTERN PACIFIC HURRICANE ODILE WITH A DEEPENING
NORTHERN STRONG SHORTWAVE RESULTING IN PERIOD OF POTENTIALLY HEAVY
SHOWERS AND THUNDERSTORMS ALONG A COLD FRONT. PRETTY COMMON FOR
SIGNIFICANT AMPLIFICATION OF LONG WAVE TROUGHS AS THEY PHASE WITH
REMNANT TROPICAL CYCLONES...AND GFS AND ECMWF BOTH SUGGEST THIS WILL
BE THE CASE EARLY NEXT WEEK WITH THE POTENTIAL FOR ANOTHER
SIGNIFICANT EARLY SEASON COLD SNAP.

IZZI

&&

.AVIATION...

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

* FOG POTENTIAL EARLY TUESDAY.
* LAKE BREEZE POTENTIAL TUESDAY AFTERNOON.

BMD

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

HIGH PRESSURE WILL BUILD TO THE SOUTH OF THE TERMINALS TONIGHT
KEEPING WINDS VERY LIGHT AND ALLOWING CONDITIONS TO REMAIN
GENERALLY VFR OUTSIDE OF SOME FOG THIS MORNING. PATCHY FOG HAS
ALREADY DEVELOPED IN SOME AREAS AND WILL MOST LIKELY IMPACT
RFD/DPA WITH CONFIDENCE TOO LOW AT ORD/MDW/GYY AT THIS TIME TO
INCLUDE ANY MENTION IN THE TAF. WINDS WILL REMAIN LIGHT GENERALLY
4-7 KT THROUGH THE DAY TUESDAY OUT OF THE NORTHWEST THOUGH THERE
MAY BE SOME VARIABILITY IN DIRECTION DUE TO THE LIGHT MAGNITUDE.
WILL ALSO HAVE TO MONITOR A LAKE BREEZE MONDAY AFTERNOON. FOR NOW
EXPECT A LAKE BREEZE TO DEVELOP BUT STAY NEAR THE SHORE.

BMD

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

* LOW CONFIDENCE IN FOG IMPACTING TERMINALS.
* LOW CONFIDENCE THAT A LAKE BREEZE WILL PUSH FAR INLAND.
* HIGH CONFIDENCE IN VFR CONDITIONS AND WINDS LESS THAN 10 KT
  THROUGH PERIOD.

BMD

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

WEDNESDAY...VFR. LIGHT WEST WINDS. LAKE BREEZE POSSIBLE.

THURSDAY...VFR. EAST WINDS.

FRIDAY...VFR. BREEZY SOUTH WINDS.

SATURDAY...CHANCE TSRA. MVFR POSSIBLE. BREEZY SOUTHWEST WINDS.

SUNDAY...SLIGHT CHANCE TSRA. VFR. WEST WINDS.

MDB

&&

.MARINE...
314 AM CDT

HIGH PRESSURE WILL BUILD ACROSS SOUTHERN LAKE MICHIGAN TODAY
ALLOWING WINDS TO DIMINISH...HOWEVER NORTHERN LAKE MICHIGAN WILL
SEE SOUTHWEST FLOW FRESHEN UP AHEAD OF THE NEXT COLD FRONT. THE
FRONT WILL SAG SOUTH ACROSS THE LAKE WEDNESDAY WITH HIGH PRESSURE
QUICKLY BUILDING IN BEHIND CAUSING A SHARP INCREASE IN WINDS
BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF THE NORTHEAST
WEDNESDAY EVENING. WINDS WILL VEER BACK AROUND TO THE SOUTHEAST
THURSDAY AND THURSDAY NIGHT DIMINISHING...THEN SOUTH TO SOUTHWEST
FRIDAY INCREASING BACK INTO THE 20 TO 25 KT RANGE...POSSIBLY 30 KT
AS BROAD LOW DEVELOPS OVER THE PLAINS AND CANADIAN PRAIRIES.

BMD

&&

.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 160814
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
314 AM CDT TUE SEP 16 2014

.DISCUSSION...
221 PM CDT

TONIGHT...
FRONTAL BOUNDARY THIS AFTERNOON CONTINUES TO SLIDE SOUTHEAST ACROSS
THE FORECAST AREA. VISIBLE IMAGERY ALONG AND JUST AHEAD OF THE
BOUNDARY INDICATED SOME VERTICAL GROWTH TO THE CLOUDS...SUGGESTIVE
OF SOME INSTABILITY. THERE HAS BEEN SOME SPOTTY CONVECTION ACROSS
NORTHEAST MO STRETCHING EAST THROUGH IL/CENTRAL IN BUT SOUTH OF THE
CWFA. DESPITE CONSIDERABLE SOLAR SHIELDING HAS BEEN ABLE TO KEEP
TEMPS IN THE 50S...WITH A FEW LOCATIONS BEING ABLE TO NUDGE TO ARND
60. WINDS WILL SHIFT NORTHWEST/NORTH BEHIND THE BOUNDARY WITH MUCH
DRIER/COOLER AIR STEADILY FILTERING INTO THE REGION OVERNIGHT.
PRECIP WILL COME TO AN END LATER THIS AFTN/EARLY EVE...WITH JUST A
FEW LINGERING SHOWERS ALONG AND EAST OF GIBSON CITY TO FOWLER. TEMPS
OVERNIGHT WILL COOL INTO THE LOW/MID 40S...WITH A FEW OF THE
TRADITIONALLY COOL SPOTS POSSIBLY DIPPING INTO THE UPR 30S BEFORE
DAYBREAK TUE. MEANWHILE CLOSER TO DOWNTOWN CHICAGO...THE URBAN HEAT
ISLAND SHUD AID IN KEEPING TEMPS IN THE UPR 40S TO ARND 50. THE ONLY
WILDCARD FOR OVERNIGHT LOWS WILL BE SKY COVER/WINDS...WHICH WITH
HIGH PRESSURE BUILDING IN SHUD ERODE/DIMINISH.

THERE IS ALSO SOME CONCERN THAT WITH THE LACK MIXING THIS AFTN AND
EXPECTED TEMPS BEING COOLER THAN AFTN DEW PTS...COUPLED WITH LIGHT
WINDS...COULD POINT TOWARDS PATCHY FOG DEVELOPING AWAY FROM THE
METRO AREA.

TUESDAY THROUGH THURSDAY...
RATHER BENIGN PATTERN FOR A GOOD PORTION OF THE WEEK. BROAD
ANTI-CYCLONIC FLOW WILL BUILD INTO THE REGION TUESDAY...WITH THE
MID-LVL TROUGH PIVOTING EAST. THE LONGWAVE PATTERN WILL LIKELY KEEP
THE REGION IN A CONTINUED NORTHWEST FLOW AS MID-LVL RIDGING RETURNS
TO THE WESTERN CONUS. GUIDANCE SUGGESTS THE SFC RIDGE THAT ARRIVES
TUE WILL SHIFT EAST...HOWEVER ANOTHER DOME OF HIGH PRESSURE FROM
CANADA IS THEN POISED TO SLIDE SOUTH AND CONTINUE THE DRY/COOL
WEATHER WED/THUR. TEMPS WILL GENERALLY REMAIN IN THE MID/UPR
60S...BUT POSSIBLY REACH 70 DEG IN SEVERAL AREAS FOR THUR. ABUNDANT
SUNSHINE IS EXPECTED EACH OF THE NEXT SEVERAL DAYS AS WELL.
OVERNIGHT LOWS WILL ALSO DIP INTO THE 40S TUE NGT/WED NGT...THEN
WITH THE SFC RIDGE BEGINNING TO PUSH EAST THUR NGT TEMPS COULD HOLD
ARND 50.

CONFIDENCE...HIGH.

FRIDAY THROUGH SUNDAY...
WITH THE SFC RIDGE POISED TO PUSH EAST OF THE REGION FRI...FLOW WILL
BE TURNING SOUTHERLY AND THE MID-LVL WAVE STARTING TO FLATTEN.
ENSEMBLES CONTINUE TO SHOW CONSIDERABLE SPREAD ON TIMING OF
PRECIP/MOISTURE RETURNING...WITH MOST MEMBERS POINTING TOWARDS FRI
NGT. THE ATMOSPHERE WILL MODERATE BY FRI/SAT WITH TEMPS IN THE
MID/UPR 70S...OR MORE SEASONAL. SAT APPEARS TO BE THE MOST FAVORABLE
PERIOD TO SEE SPOTTY SHOWERS/THUNDERSTORMS AS A MID-LVL TROUGH
DEVELOPS OVER THE CENTRAL PLAINS AND NEARS THE REGION SAT AFTN/EVE.
THEN FOR THE SECOND HALF OF THE WEEKEND SFC RIDGING IS PROGGED TO
RETURN TO THE REGION.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* FOG POTENTIAL EARLY TUESDAY.
* LAKE BREEZE POTENTIAL TUESDAY AFTERNOON.

BMD

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

HIGH PRESSURE WILL BUILD TO THE SOUTH OF THE TERMINALS TONIGHT
KEEPING WINDS VERY LIGHT AND ALLOWING CONDITIONS TO REMAIN
GENERALLY VFR OUTSIDE OF SOME FOG THIS MORNING. PATCHY FOG HAS
ALREADY DEVELOPED IN SOME AREAS AND WILL MOST LIKELY IMPACT
RFD/DPA WITH CONFIDENCE TOO LOW AT ORD/MDW/GYY AT THIS TIME TO
INCLUDE ANY MENTION IN THE TAF. WINDS WILL REMAIN LIGHT GENERALLY
4-7 KT THROUGH THE DAY TUESDAY OUT OF THE NORTHWEST THOUGH THERE
MAY BE SOME VARIABILITY IN DIRECTION DUE TO THE LIGHT MAGNITUDE.
WILL ALSO HAVE TO MONITOR A LAKE BREEZE MONDAY AFTERNOON. FOR NOW
EXPECT A LAKE BREEZE TO DEVELOP BUT STAY NEAR THE SHORE.

BMD

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

* LOW CONFIDENCE IN FOG IMPACTING TERMINALS.
* LOW CONFIDENCE THAT A LAKE BREEZE WILL PUSH FAR INLAND.
* HIGH CONFIDENCE IN VFR CONDITIONS AND WINDS LESS THAN 10 KT
  THROUGH PERIOD.

BMD

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

WEDNESDAY...VFR. LIGHT WEST WINDS. LAKE BREEZE POSSIBLE.

THURSDAY...VFR. EAST WINDS.

FRIDAY...VFR. BREEZY SOUTH WINDS.

SATURDAY...CHANCE TSRA. MVFR POSSIBLE. BREEZY SOUTHWEST WINDS.

SUNDAY...SLIGHT CHANCE TSRA. VFR. WEST WINDS.

MDB

&&

.MARINE...
314 AM CDT

HIGH PRESSURE WILL BUILD ACROSS SOUTHERN LAKE MICHIGAN TODAY
ALLOWING WINDS TO DIMINISH...HOWEVER NORTHERN LAKE MICHIGAN WILL
SEE SOUTHWEST FLOW FRESHEN UP AHEAD OF THE NEXT COLD FRONT. THE
FRONT WILL SAG SOUTH ACROSS THE LAKE WEDNESDAY WITH HIGH PRESSURE
QUICKLY BUILDING IN BEHIND CAUSING A SHARP INCREASE IN WINDS
BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF THE NORTHEAST
WEDNESDAY EVENING. WINDS WILL VEER BACK AROUND TO THE SOUTHEAST
THURSDAY AND THURSDAY NIGHT DIMINISHING...THEN SOUTH TO SOUTHWEST
FRIDAY INCREASING BACK INTO THE 20 TO 25 KT RANGE...POSSIBLY 30 KT
AS BROAD LOW DEVELOPS OVER THE PLAINS AND CANADIAN PRAIRIES.

BMD

&&

.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 160814
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
314 AM CDT TUE SEP 16 2014

.DISCUSSION...
221 PM CDT

TONIGHT...
FRONTAL BOUNDARY THIS AFTERNOON CONTINUES TO SLIDE SOUTHEAST ACROSS
THE FORECAST AREA. VISIBLE IMAGERY ALONG AND JUST AHEAD OF THE
BOUNDARY INDICATED SOME VERTICAL GROWTH TO THE CLOUDS...SUGGESTIVE
OF SOME INSTABILITY. THERE HAS BEEN SOME SPOTTY CONVECTION ACROSS
NORTHEAST MO STRETCHING EAST THROUGH IL/CENTRAL IN BUT SOUTH OF THE
CWFA. DESPITE CONSIDERABLE SOLAR SHIELDING HAS BEEN ABLE TO KEEP
TEMPS IN THE 50S...WITH A FEW LOCATIONS BEING ABLE TO NUDGE TO ARND
60. WINDS WILL SHIFT NORTHWEST/NORTH BEHIND THE BOUNDARY WITH MUCH
DRIER/COOLER AIR STEADILY FILTERING INTO THE REGION OVERNIGHT.
PRECIP WILL COME TO AN END LATER THIS AFTN/EARLY EVE...WITH JUST A
FEW LINGERING SHOWERS ALONG AND EAST OF GIBSON CITY TO FOWLER. TEMPS
OVERNIGHT WILL COOL INTO THE LOW/MID 40S...WITH A FEW OF THE
TRADITIONALLY COOL SPOTS POSSIBLY DIPPING INTO THE UPR 30S BEFORE
DAYBREAK TUE. MEANWHILE CLOSER TO DOWNTOWN CHICAGO...THE URBAN HEAT
ISLAND SHUD AID IN KEEPING TEMPS IN THE UPR 40S TO ARND 50. THE ONLY
WILDCARD FOR OVERNIGHT LOWS WILL BE SKY COVER/WINDS...WHICH WITH
HIGH PRESSURE BUILDING IN SHUD ERODE/DIMINISH.

THERE IS ALSO SOME CONCERN THAT WITH THE LACK MIXING THIS AFTN AND
EXPECTED TEMPS BEING COOLER THAN AFTN DEW PTS...COUPLED WITH LIGHT
WINDS...COULD POINT TOWARDS PATCHY FOG DEVELOPING AWAY FROM THE
METRO AREA.

TUESDAY THROUGH THURSDAY...
RATHER BENIGN PATTERN FOR A GOOD PORTION OF THE WEEK. BROAD
ANTI-CYCLONIC FLOW WILL BUILD INTO THE REGION TUESDAY...WITH THE
MID-LVL TROUGH PIVOTING EAST. THE LONGWAVE PATTERN WILL LIKELY KEEP
THE REGION IN A CONTINUED NORTHWEST FLOW AS MID-LVL RIDGING RETURNS
TO THE WESTERN CONUS. GUIDANCE SUGGESTS THE SFC RIDGE THAT ARRIVES
TUE WILL SHIFT EAST...HOWEVER ANOTHER DOME OF HIGH PRESSURE FROM
CANADA IS THEN POISED TO SLIDE SOUTH AND CONTINUE THE DRY/COOL
WEATHER WED/THUR. TEMPS WILL GENERALLY REMAIN IN THE MID/UPR
60S...BUT POSSIBLY REACH 70 DEG IN SEVERAL AREAS FOR THUR. ABUNDANT
SUNSHINE IS EXPECTED EACH OF THE NEXT SEVERAL DAYS AS WELL.
OVERNIGHT LOWS WILL ALSO DIP INTO THE 40S TUE NGT/WED NGT...THEN
WITH THE SFC RIDGE BEGINNING TO PUSH EAST THUR NGT TEMPS COULD HOLD
ARND 50.

CONFIDENCE...HIGH.

FRIDAY THROUGH SUNDAY...
WITH THE SFC RIDGE POISED TO PUSH EAST OF THE REGION FRI...FLOW WILL
BE TURNING SOUTHERLY AND THE MID-LVL WAVE STARTING TO FLATTEN.
ENSEMBLES CONTINUE TO SHOW CONSIDERABLE SPREAD ON TIMING OF
PRECIP/MOISTURE RETURNING...WITH MOST MEMBERS POINTING TOWARDS FRI
NGT. THE ATMOSPHERE WILL MODERATE BY FRI/SAT WITH TEMPS IN THE
MID/UPR 70S...OR MORE SEASONAL. SAT APPEARS TO BE THE MOST FAVORABLE
PERIOD TO SEE SPOTTY SHOWERS/THUNDERSTORMS AS A MID-LVL TROUGH
DEVELOPS OVER THE CENTRAL PLAINS AND NEARS THE REGION SAT AFTN/EVE.
THEN FOR THE SECOND HALF OF THE WEEKEND SFC RIDGING IS PROGGED TO
RETURN TO THE REGION.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* FOG POTENTIAL EARLY TUESDAY.
* LAKE BREEZE POTENTIAL TUESDAY AFTERNOON.

BMD

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

HIGH PRESSURE WILL BUILD TO THE SOUTH OF THE TERMINALS TONIGHT
KEEPING WINDS VERY LIGHT AND ALLOWING CONDITIONS TO REMAIN
GENERALLY VFR OUTSIDE OF SOME FOG THIS MORNING. PATCHY FOG HAS
ALREADY DEVELOPED IN SOME AREAS AND WILL MOST LIKELY IMPACT
RFD/DPA WITH CONFIDENCE TOO LOW AT ORD/MDW/GYY AT THIS TIME TO
INCLUDE ANY MENTION IN THE TAF. WINDS WILL REMAIN LIGHT GENERALLY
4-7 KT THROUGH THE DAY TUESDAY OUT OF THE NORTHWEST THOUGH THERE
MAY BE SOME VARIABILITY IN DIRECTION DUE TO THE LIGHT MAGNITUDE.
WILL ALSO HAVE TO MONITOR A LAKE BREEZE MONDAY AFTERNOON. FOR NOW
EXPECT A LAKE BREEZE TO DEVELOP BUT STAY NEAR THE SHORE.

BMD

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

* LOW CONFIDENCE IN FOG IMPACTING TERMINALS.
* LOW CONFIDENCE THAT A LAKE BREEZE WILL PUSH FAR INLAND.
* HIGH CONFIDENCE IN VFR CONDITIONS AND WINDS LESS THAN 10 KT
  THROUGH PERIOD.

BMD

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

WEDNESDAY...VFR. LIGHT WEST WINDS. LAKE BREEZE POSSIBLE.

THURSDAY...VFR. EAST WINDS.

FRIDAY...VFR. BREEZY SOUTH WINDS.

SATURDAY...CHANCE TSRA. MVFR POSSIBLE. BREEZY SOUTHWEST WINDS.

SUNDAY...SLIGHT CHANCE TSRA. VFR. WEST WINDS.

MDB

&&

.MARINE...
314 AM CDT

HIGH PRESSURE WILL BUILD ACROSS SOUTHERN LAKE MICHIGAN TODAY
ALLOWING WINDS TO DIMINISH...HOWEVER NORTHERN LAKE MICHIGAN WILL
SEE SOUTHWEST FLOW FRESHEN UP AHEAD OF THE NEXT COLD FRONT. THE
FRONT WILL SAG SOUTH ACROSS THE LAKE WEDNESDAY WITH HIGH PRESSURE
QUICKLY BUILDING IN BEHIND CAUSING A SHARP INCREASE IN WINDS
BEHIND THE FRONT INTO THE 20 TO 25 KT RANGE OUT OF THE NORTHEAST
WEDNESDAY EVENING. WINDS WILL VEER BACK AROUND TO THE SOUTHEAST
THURSDAY AND THURSDAY NIGHT DIMINISHING...THEN SOUTH TO SOUTHWEST
FRIDAY INCREASING BACK INTO THE 20 TO 25 KT RANGE...POSSIBLY 30 KT
AS BROAD LOW DEVELOPS OVER THE PLAINS AND CANADIAN PRAIRIES.

BMD

&&

.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 160730
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
230 AM CDT Tue Sep 16 2014

.SHORT TERM...(Today)
ISSUED AT 230 AM CDT TUE SEP 16 2014

Quiet weather expected overall today across central and southeast
Illinois. Canadian high pressure and its associated dry air mass will
continue to build into the area today, helping to scour out the low
clouds that currently reside across much of the forecast area. The
low clouds have been clearing slowly from the north as the high
builds in, and the latest trends suggest the clearing should reach
the I-70 corridor by 10 a.m. this morning. Once the skies clear,
mostly sunny skies should be the rule, as forecast soundings and CU
rule suggest diurnal cloud development should be minimal. The
possible exception to the clearing sticking, at least until sunrise,
is the potential for fog/stratus development. This development has
been patchy thus far upstream, and do not expect it to become too
widespread. Temperatures today, as they have been more often than
not lately, will be well below normal with highs mainly in the
mid-upper 60s.


&&

.LONG TERM...(Tonight through Monday)
ISSUED AT 230 AM CDT TUE SEP 16 2014

High pressure building southeast into the Great Lakes to dominate
our weather through Thursday. Latest model guidance continues to
indicate some sort of MCS type activity across Missouri and Kansas
Wednesday into Thursday, sliding along the edge of the upper ridge
that will slowly inch eastward into the Plains. However, the
persistent east/northeast flow over our area should keep this
precipitation at bay.

Significant shortwave will dig as it crosses the Rockies on Friday,
settling into the Mississippi Valley by Sunday morning. Have largely
kept the forecast dry through about midday Saturday, then quickly
increased the PoP`s from west to east during the afternoon and
evening hours, as the front arrives. One significant item of concern
is with the potential for heavy rain. The remnants of tropical
cyclone Odile over Baja California will be spreading into the Desert
Southwest over the next day or so. The latest GFS model continues to
show that a piece of energy and associated moisture from this system
will be drawn northeast into the northern wave, reaching central
Illinois after midnight Saturday night with the potential for a few
inches of rain. The ECMWF and Canadian models are not quite as
generous on this point, but do draw in some of the moisture into the
wave by Saturday morning and produce weekend rainfalls of up to 1.5
inches. Have increased PoP`s Saturday night to around 60% across
most of the forecast area, as confidence increases in the general
rainfall trend over the area. Continued the PoP`s on Sunday east of
I-55, although this should be winding down during the afternoon as
the front exits the area.

A large broad upper trough will persist over the Midwest early next
week in the wake of this system. Latest ECMWF model has
significantly backed down on the amount of cool air with this
system, with 850 mb temperatures on Monday now around +5C rather
than the -2C from the previous run. The GFS lags behind the ECMWF
with bringing the cooler conditions into the area. As a result, have
kept highs in the 70s on Sunday and Monday, with the coolest
conditions just beyond the current forecast period.


&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
ISSUED AT 1137 PM CDT MON SEP 15 2014

Precip has departed well to the southeast of all terminal sites,
with clearing of the clouds expected to reach PIA by 05z and
progressing to CMI/DEC around 0730z. Still expect some fog
formation after the clearing develops, with a few areas developing
VLIFR ceilings and fog. A bit of a tough call on timing and
coverage of any dense fog, but for now BMI and CMI were the only
two locations with LIFR/VLIFR conditions between 11z-13z. The
latest HRRR keeps low vis east of CMI, with lingering low clouds
after midnight at all sites by PIA. It is possible that a stratus
layer forms instead of ground fog, but will lean toward fog
formation with this set of TAFs.

Skies should clear out quickly Tues morning with very dry air
above the shallow layer of moisture. Clear skies will continue
through the remainder of the TAF period to 06z/16.

Winds have become N behind the departing cold front, with a brief
increase in wind speeds to 10-12kt. Light winds should prevail the
remainder of the night and into Tuesday, as high pressure keeps
the pressure gradient weak.


&&

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

$$

SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...SHIMON






000
FXUS63 KILX 160730
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
230 AM CDT Tue Sep 16 2014

.SHORT TERM...(Today)
ISSUED AT 230 AM CDT TUE SEP 16 2014

Quiet weather expected overall today across central and southeast
Illinois. Canadian high pressure and its associated dry air mass will
continue to build into the area today, helping to scour out the low
clouds that currently reside across much of the forecast area. The
low clouds have been clearing slowly from the north as the high
builds in, and the latest trends suggest the clearing should reach
the I-70 corridor by 10 a.m. this morning. Once the skies clear,
mostly sunny skies should be the rule, as forecast soundings and CU
rule suggest diurnal cloud development should be minimal. The
possible exception to the clearing sticking, at least until sunrise,
is the potential for fog/stratus development. This development has
been patchy thus far upstream, and do not expect it to become too
widespread. Temperatures today, as they have been more often than
not lately, will be well below normal with highs mainly in the
mid-upper 60s.


&&

.LONG TERM...(Tonight through Monday)
ISSUED AT 230 AM CDT TUE SEP 16 2014

High pressure building southeast into the Great Lakes to dominate
our weather through Thursday. Latest model guidance continues to
indicate some sort of MCS type activity across Missouri and Kansas
Wednesday into Thursday, sliding along the edge of the upper ridge
that will slowly inch eastward into the Plains. However, the
persistent east/northeast flow over our area should keep this
precipitation at bay.

Significant shortwave will dig as it crosses the Rockies on Friday,
settling into the Mississippi Valley by Sunday morning. Have largely
kept the forecast dry through about midday Saturday, then quickly
increased the PoP`s from west to east during the afternoon and
evening hours, as the front arrives. One significant item of concern
is with the potential for heavy rain. The remnants of tropical
cyclone Odile over Baja California will be spreading into the Desert
Southwest over the next day or so. The latest GFS model continues to
show that a piece of energy and associated moisture from this system
will be drawn northeast into the northern wave, reaching central
Illinois after midnight Saturday night with the potential for a few
inches of rain. The ECMWF and Canadian models are not quite as
generous on this point, but do draw in some of the moisture into the
wave by Saturday morning and produce weekend rainfalls of up to 1.5
inches. Have increased PoP`s Saturday night to around 60% across
most of the forecast area, as confidence increases in the general
rainfall trend over the area. Continued the PoP`s on Sunday east of
I-55, although this should be winding down during the afternoon as
the front exits the area.

A large broad upper trough will persist over the Midwest early next
week in the wake of this system. Latest ECMWF model has
significantly backed down on the amount of cool air with this
system, with 850 mb temperatures on Monday now around +5C rather
than the -2C from the previous run. The GFS lags behind the ECMWF
with bringing the cooler conditions into the area. As a result, have
kept highs in the 70s on Sunday and Monday, with the coolest
conditions just beyond the current forecast period.


&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
ISSUED AT 1137 PM CDT MON SEP 15 2014

Precip has departed well to the southeast of all terminal sites,
with clearing of the clouds expected to reach PIA by 05z and
progressing to CMI/DEC around 0730z. Still expect some fog
formation after the clearing develops, with a few areas developing
VLIFR ceilings and fog. A bit of a tough call on timing and
coverage of any dense fog, but for now BMI and CMI were the only
two locations with LIFR/VLIFR conditions between 11z-13z. The
latest HRRR keeps low vis east of CMI, with lingering low clouds
after midnight at all sites by PIA. It is possible that a stratus
layer forms instead of ground fog, but will lean toward fog
formation with this set of TAFs.

Skies should clear out quickly Tues morning with very dry air
above the shallow layer of moisture. Clear skies will continue
through the remainder of the TAF period to 06z/16.

Winds have become N behind the departing cold front, with a brief
increase in wind speeds to 10-12kt. Light winds should prevail the
remainder of the night and into Tuesday, as high pressure keeps
the pressure gradient weak.


&&

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

$$

SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...SHIMON







000
FXUS63 KLOT 160529
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1229 AM CDT TUE SEP 16 2014

.DISCUSSION...
221 PM CDT

TONIGHT...
FRONTAL BOUNDARY THIS AFTERNOON CONTINUES TO SLIDE SOUTHEAST ACROSS
THE FORECAST AREA. VISIBLE IMAGERY ALONG AND JUST AHEAD OF THE
BOUNDARY INDICATED SOME VERTICAL GROWTH TO THE CLOUDS...SUGGESTIVE
OF SOME INSTABILITY. THERE HAS BEEN SOME SPOTTY CONVECTION ACROSS
NORTHEAST MO STRETCHING EAST THROUGH IL/CENTRAL IN BUT SOUTH OF THE
CWFA. DESPITE CONSIDERABLE SOLAR SHIELDING HAS BEEN ABLE TO KEEP
TEMPS IN THE 50S...WITH A FEW LOCATIONS BEING ABLE TO NUDGE TO ARND
60. WINDS WILL SHIFT NORTHWEST/NORTH BEHIND THE BOUNDARY WITH MUCH
DRIER/COOLER AIR STEADILY FILTERING INTO THE REGION OVERNIGHT.
PRECIP WILL COME TO AN END LATER THIS AFTN/EARLY EVE...WITH JUST A
FEW LINGERING SHOWERS ALONG AND EAST OF GIBSON CITY TO FOWLER. TEMPS
OVERNIGHT WILL COOL INTO THE LOW/MID 40S...WITH A FEW OF THE
TRADITIONALLY COOL SPOTS POSSIBLY DIPPING INTO THE UPR 30S BEFORE
DAYBREAK TUE. MEANWHILE CLOSER TO DOWNTOWN CHICAGO...THE URBAN HEAT
ISLAND SHUD AID IN KEEPING TEMPS IN THE UPR 40S TO ARND 50. THE ONLY
WILDCARD FOR OVERNIGHT LOWS WILL BE SKY COVER/WINDS...WHICH WITH
HIGH PRESSURE BUILDING IN SHUD ERODE/DIMINISH.

THERE IS ALSO SOME CONCERN THAT WITH THE LACK MIXING THIS AFTN AND
EXPECTED TEMPS BEING COOLER THAN AFTN DEW PTS...COUPLED WITH LIGHT
WINDS...COULD POINT TOWARDS PATCHY FOG DEVELOPING AWAY FROM THE
METRO AREA.

TUESDAY THROUGH THURSDAY...
RATHER BENIGN PATTERN FOR A GOOD PORTION OF THE WEEK. BROAD
ANTI-CYCLONIC FLOW WILL BUILD INTO THE REGION TUESDAY...WITH THE
MID-LVL TROUGH PIVOTING EAST. THE LONGWAVE PATTERN WILL LIKELY KEEP
THE REGION IN A CONTINUED NORTHWEST FLOW AS MID-LVL RIDGING RETURNS
TO THE WESTERN CONUS. GUIDANCE SUGGESTS THE SFC RIDGE THAT ARRIVES
TUE WILL SHIFT EAST...HOWEVER ANOTHER DOME OF HIGH PRESSURE FROM
CANADA IS THEN POISED TO SLIDE SOUTH AND CONTINUE THE DRY/COOL
WEATHER WED/THUR. TEMPS WILL GENERALLY REMAIN IN THE MID/UPR
60S...BUT POSSIBLY REACH 70 DEG IN SEVERAL AREAS FOR THUR. ABUNDANT
SUNSHINE IS EXPECTED EACH OF THE NEXT SEVERAL DAYS AS WELL.
OVERNIGHT LOWS WILL ALSO DIP INTO THE 40S TUE NGT/WED NGT...THEN
WITH THE SFC RIDGE BEGINNING TO PUSH EAST THUR NGT TEMPS COULD HOLD
ARND 50.

CONFIDENCE...HIGH.

FRIDAY THROUGH SUNDAY...
WITH THE SFC RIDGE POISED TO PUSH EAST OF THE REGION FRI...FLOW WILL
BE TURNING SOUTHERLY AND THE MID-LVL WAVE STARTING TO FLATTEN.
ENSEMBLES CONTINUE TO SHOW CONSIDERABLE SPREAD ON TIMING OF
PRECIP/MOISTURE RETURNING...WITH MOST MEMBERS POINTING TOWARDS FRI
NGT. THE ATMOSPHERE WILL MODERATE BY FRI/SAT WITH TEMPS IN THE
MID/UPR 70S...OR MORE SEASONAL. SAT APPEARS TO BE THE MOST FAVORABLE
PERIOD TO SEE SPOTTY SHOWERS/THUNDERSTORMS AS A MID-LVL TROUGH
DEVELOPS OVER THE CENTRAL PLAINS AND NEARS THE REGION SAT AFTN/EVE.
THEN FOR THE SECOND HALF OF THE WEEKEND SFC RIDGING IS PROGGED TO
RETURN TO THE REGION.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* FOG POTENTIAL EARLY TUESDAY.
* LAKE BREEZE POTENTIAL TUESDAY AFTERNOON.

BMD

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

HIGH PRESSURE WILL BUILD TO THE SOUTH OF THE TERMINALS TONIGHT
KEEPING WINDS VERY LIGHT AND ALLOWING CONDITIONS TO REMAIN
GENERALLY VFR OUTSIDE OF SOME FOG THIS MORNING. PATCHY FOG HAS
ALREADY DEVELOPED IN SOME AREAS AND WILL MOST LIKELY IMPACT
RFD/DPA WITH CONFIDENCE TOO LOW AT ORD/MDW/GYY AT THIS TIME TO
INCLUDE ANY MENTION IN THE TAF. WINDS WILL REMAIN LIGHT GENERALLY
4-7 KT THROUGH THE DAY TUESDAY OUT OF THE NORTHWEST THOUGH THERE
MAY BE SOME VARIABILITY IN DIRECTION DUE TO THE LIGHT MAGNITUDE.
WILL ALSO HAVE TO MONITOR A LAKE BREEZE MONDAY AFTERNOON. FOR NOW
EXPECT A LAKE BREEZE TO DEVELOP BUT STAY NEAR THE SHORE.

BMD

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

* LOW CONFIDENCE IN FOG IMPACTING TERMINALS.
* LOW CONFIDENCE THAT A LAKE BREEZE WILL PUSH FAR INLAND.
* HIGH CONFIDENCE IN VFR CONDITIONS AND WINDS LESS THAN 10 KT
  THROUGH PERIOD.

BMD

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

WEDNESDAY...VFR. LIGHT WEST WINDS. LAKE BREEZE POSSIBLE.

THURSDAY...VFR. EAST WINDS.

FRIDAY...VFR. BREEZY SOUTH WINDS.

SATURDAY...CHANCE TSRA. MVFR POSSIBLE. BREEZY SOUTHWEST WINDS.

SUNDAY...SLIGHT CHANCE TSRA. VFR. WEST WINDS.

MDB

&&

.MARINE...
246 PM CDT

WEAK LOW PRESSURE WILL PUSH EAST THROUGH THE OHIO VALLEY AND
DISSIPATE THIS EVENING AS HIGH PRESSURE MOVES INTO THE MID
MISSOURI VALLEY TONIGHT. AHEAD OF THE HIGH A WEAK COLD FRONT WILL
SPREAD DOWN THE REMAINDER OF THE LAKE THIS EVENING AND BRIEFLY
INCREASE NORTH WINDS TO NEAR 20 KT THE HIGH WILL WEAKEN AND MOVE
OVER LAKE MICHIGAN ON TUESDAY. LOW PRESSURE OVER HUDSON BAY WILL
SPREAD INTO QUEBEC ON WEDNESDAY AS HIGH PRESSURE PUSHES SOUTH OUT
OF NORTHERN MANITOBA. AHEAD OF THE HIGH THE SOUTHWEST GRADIENT
INCREASES WITH WINDS 15 TO 25 KT FOR THE NORTH HALF OF THE LAKE. THE
HIGH REACHES LAKE SUPERIOR THURSDAY EVENING AND WILL PUSH A COLD
FRONT DOWN THE LAKE THURSDAY NIGHT. THIS HIGH WILL THEN MOVE TO
THE EASTERN LAKES BY LATE THURSDAY INTO FRIDAY AS SEVERAL LOWS
ORGANIZE IN THE CENTRAL PLAINS AND CANADIAN PRAIRIES.

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 160529
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1229 AM CDT TUE SEP 16 2014

.DISCUSSION...
221 PM CDT

TONIGHT...
FRONTAL BOUNDARY THIS AFTERNOON CONTINUES TO SLIDE SOUTHEAST ACROSS
THE FORECAST AREA. VISIBLE IMAGERY ALONG AND JUST AHEAD OF THE
BOUNDARY INDICATED SOME VERTICAL GROWTH TO THE CLOUDS...SUGGESTIVE
OF SOME INSTABILITY. THERE HAS BEEN SOME SPOTTY CONVECTION ACROSS
NORTHEAST MO STRETCHING EAST THROUGH IL/CENTRAL IN BUT SOUTH OF THE
CWFA. DESPITE CONSIDERABLE SOLAR SHIELDING HAS BEEN ABLE TO KEEP
TEMPS IN THE 50S...WITH A FEW LOCATIONS BEING ABLE TO NUDGE TO ARND
60. WINDS WILL SHIFT NORTHWEST/NORTH BEHIND THE BOUNDARY WITH MUCH
DRIER/COOLER AIR STEADILY FILTERING INTO THE REGION OVERNIGHT.
PRECIP WILL COME TO AN END LATER THIS AFTN/EARLY EVE...WITH JUST A
FEW LINGERING SHOWERS ALONG AND EAST OF GIBSON CITY TO FOWLER. TEMPS
OVERNIGHT WILL COOL INTO THE LOW/MID 40S...WITH A FEW OF THE
TRADITIONALLY COOL SPOTS POSSIBLY DIPPING INTO THE UPR 30S BEFORE
DAYBREAK TUE. MEANWHILE CLOSER TO DOWNTOWN CHICAGO...THE URBAN HEAT
ISLAND SHUD AID IN KEEPING TEMPS IN THE UPR 40S TO ARND 50. THE ONLY
WILDCARD FOR OVERNIGHT LOWS WILL BE SKY COVER/WINDS...WHICH WITH
HIGH PRESSURE BUILDING IN SHUD ERODE/DIMINISH.

THERE IS ALSO SOME CONCERN THAT WITH THE LACK MIXING THIS AFTN AND
EXPECTED TEMPS BEING COOLER THAN AFTN DEW PTS...COUPLED WITH LIGHT
WINDS...COULD POINT TOWARDS PATCHY FOG DEVELOPING AWAY FROM THE
METRO AREA.

TUESDAY THROUGH THURSDAY...
RATHER BENIGN PATTERN FOR A GOOD PORTION OF THE WEEK. BROAD
ANTI-CYCLONIC FLOW WILL BUILD INTO THE REGION TUESDAY...WITH THE
MID-LVL TROUGH PIVOTING EAST. THE LONGWAVE PATTERN WILL LIKELY KEEP
THE REGION IN A CONTINUED NORTHWEST FLOW AS MID-LVL RIDGING RETURNS
TO THE WESTERN CONUS. GUIDANCE SUGGESTS THE SFC RIDGE THAT ARRIVES
TUE WILL SHIFT EAST...HOWEVER ANOTHER DOME OF HIGH PRESSURE FROM
CANADA IS THEN POISED TO SLIDE SOUTH AND CONTINUE THE DRY/COOL
WEATHER WED/THUR. TEMPS WILL GENERALLY REMAIN IN THE MID/UPR
60S...BUT POSSIBLY REACH 70 DEG IN SEVERAL AREAS FOR THUR. ABUNDANT
SUNSHINE IS EXPECTED EACH OF THE NEXT SEVERAL DAYS AS WELL.
OVERNIGHT LOWS WILL ALSO DIP INTO THE 40S TUE NGT/WED NGT...THEN
WITH THE SFC RIDGE BEGINNING TO PUSH EAST THUR NGT TEMPS COULD HOLD
ARND 50.

CONFIDENCE...HIGH.

FRIDAY THROUGH SUNDAY...
WITH THE SFC RIDGE POISED TO PUSH EAST OF THE REGION FRI...FLOW WILL
BE TURNING SOUTHERLY AND THE MID-LVL WAVE STARTING TO FLATTEN.
ENSEMBLES CONTINUE TO SHOW CONSIDERABLE SPREAD ON TIMING OF
PRECIP/MOISTURE RETURNING...WITH MOST MEMBERS POINTING TOWARDS FRI
NGT. THE ATMOSPHERE WILL MODERATE BY FRI/SAT WITH TEMPS IN THE
MID/UPR 70S...OR MORE SEASONAL. SAT APPEARS TO BE THE MOST FAVORABLE
PERIOD TO SEE SPOTTY SHOWERS/THUNDERSTORMS AS A MID-LVL TROUGH
DEVELOPS OVER THE CENTRAL PLAINS AND NEARS THE REGION SAT AFTN/EVE.
THEN FOR THE SECOND HALF OF THE WEEKEND SFC RIDGING IS PROGGED TO
RETURN TO THE REGION.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* FOG POTENTIAL EARLY TUESDAY.
* LAKE BREEZE POTENTIAL TUESDAY AFTERNOON.

BMD

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

HIGH PRESSURE WILL BUILD TO THE SOUTH OF THE TERMINALS TONIGHT
KEEPING WINDS VERY LIGHT AND ALLOWING CONDITIONS TO REMAIN
GENERALLY VFR OUTSIDE OF SOME FOG THIS MORNING. PATCHY FOG HAS
ALREADY DEVELOPED IN SOME AREAS AND WILL MOST LIKELY IMPACT
RFD/DPA WITH CONFIDENCE TOO LOW AT ORD/MDW/GYY AT THIS TIME TO
INCLUDE ANY MENTION IN THE TAF. WINDS WILL REMAIN LIGHT GENERALLY
4-7 KT THROUGH THE DAY TUESDAY OUT OF THE NORTHWEST THOUGH THERE
MAY BE SOME VARIABILITY IN DIRECTION DUE TO THE LIGHT MAGNITUDE.
WILL ALSO HAVE TO MONITOR A LAKE BREEZE MONDAY AFTERNOON. FOR NOW
EXPECT A LAKE BREEZE TO DEVELOP BUT STAY NEAR THE SHORE.

BMD

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

* LOW CONFIDENCE IN FOG IMPACTING TERMINALS.
* LOW CONFIDENCE THAT A LAKE BREEZE WILL PUSH FAR INLAND.
* HIGH CONFIDENCE IN VFR CONDITIONS AND WINDS LESS THAN 10 KT
  THROUGH PERIOD.

BMD

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

WEDNESDAY...VFR. LIGHT WEST WINDS. LAKE BREEZE POSSIBLE.

THURSDAY...VFR. EAST WINDS.

FRIDAY...VFR. BREEZY SOUTH WINDS.

SATURDAY...CHANCE TSRA. MVFR POSSIBLE. BREEZY SOUTHWEST WINDS.

SUNDAY...SLIGHT CHANCE TSRA. VFR. WEST WINDS.

MDB

&&

.MARINE...
246 PM CDT

WEAK LOW PRESSURE WILL PUSH EAST THROUGH THE OHIO VALLEY AND
DISSIPATE THIS EVENING AS HIGH PRESSURE MOVES INTO THE MID
MISSOURI VALLEY TONIGHT. AHEAD OF THE HIGH A WEAK COLD FRONT WILL
SPREAD DOWN THE REMAINDER OF THE LAKE THIS EVENING AND BRIEFLY
INCREASE NORTH WINDS TO NEAR 20 KT THE HIGH WILL WEAKEN AND MOVE
OVER LAKE MICHIGAN ON TUESDAY. LOW PRESSURE OVER HUDSON BAY WILL
SPREAD INTO QUEBEC ON WEDNESDAY AS HIGH PRESSURE PUSHES SOUTH OUT
OF NORTHERN MANITOBA. AHEAD OF THE HIGH THE SOUTHWEST GRADIENT
INCREASES WITH WINDS 15 TO 25 KT FOR THE NORTH HALF OF THE LAKE. THE
HIGH REACHES LAKE SUPERIOR THURSDAY EVENING AND WILL PUSH A COLD
FRONT DOWN THE LAKE THURSDAY NIGHT. THIS HIGH WILL THEN MOVE TO
THE EASTERN LAKES BY LATE THURSDAY INTO FRIDAY AS SEVERAL LOWS
ORGANIZE IN THE CENTRAL PLAINS AND CANADIAN PRAIRIES.

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 160438
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1138 PM CDT Mon Sep 15 2014

.UPDATE...
ISSUED AT 900 PM CDT MON SEP 15 2014

Showers and drizzle are departing quickly to the southeast, with
the back edge of the clouds approaching faster than previously
expected as well. The latest HRRR is indicating a band of low
clouds are expected to redevelop behind the clearing, moving into
our counties from the northeast toward Lake Michigan. Low level
wind patterns and obs from that area show some support for that
solution. Have updated the sky grids to acknowledge both the
initial clearing and subsequent clouds from the NE for a few hours
after. Any areas that clear out will have a good chance of seeing
fog develop. The light winds later tonight could set the stage for
locally dense fog, especially NW of I-55 where clearing will
develop sooner. Dewpoints will remain relatively high for enough
hours after clearing that lows will drop very close to the
dewpoint in those areas. Added fog to the weather grids
accordingly. Updated info is already available.

&&

.SHORT TERM...(Tonight)
ISSUED AT 321 PM CDT MON SEP 15 2014

Storm system still impacting Central Illinois ahead of an
approaching boundary.  Some low clouds and developing fog in the
wake of the showers hint to the main issues going into the overnight
hours tonight.  Showers and thunderstorms should begin to wrap up
this evening but wet, misty, and low clouds should continue for a
little while at least.  Satellite imagery showing the low clouds
hanging around a bit after the wind shift/boundary moves through
with the NW/N winds.  Cooler tonight...but coolest in the NW where
most likely to see some clearing.  Temps may bottom out locally if
the cigs clear in the overnight.  Either way, enhanced llvl moisture
will bring with it the chance for fog development.  For now,
question is between dense fog and very low stratus.  Stratus already
developing and see no reason to break that trend, so only putting in
patchy fog mention in the overnight hours.

&&

.LONG TERM...(Tuesday through Monday)
ISSUED AT 321 PM CDT MON SEP 15 2014

The medium and long range models are in generally good agreement
that a progressive upper level flow pattern will dominate through
the next seven days.

Surface high pressure from the northern Plains will work its way
toward the Midwest Tuesday, resulting in a clearing sky and a
continuation of cooler than normal temperatures. A weak shortwave
trough in the upper level northwest flow will approach the
mid-Mississippi River valley Wednesday. However, an abundance of dry
air in the lower levels should keep central and eastern IL
rain-free. Would not be surprised to see a sprinkle or two in areas
southwest of a Rushville-Springfield line. Will hold off on the
mention of that for now as the favorable moisture and lift appears
to stay along and west of the MS River.

Anticyclonic low level flow will continue to dominate through
Thursday and Friday keeping rain out of the forecast. A return,
southerly flow Friday will finally allow temperatures to climb
toward seasonal levels in the 75-80 range across most of central and
southeast IL.

Will keep the potential for showers and thunderstorms in the
forecast west of I-57 Saturday, and across all of central and
eastern IL Saturday night. The European and GFS models are actually
in quite good agreement that an upper level trough will advance from
the Rockies Friday to the Midwest later Saturday. The southerly low
level flow will advect plenty of moisture ahead of the surface cold
front, resulting in showers and thunderstorms. However, there is the
potential for heavy rain from this system, particularly according to
the GFS solution. The GFS depicts the remnants of Hurricane Odile,
currently in the southern California Baja region, ejecting toward
the central U.S. with deep tropical moisture. This would easily
result in 1-3" of rain across much of the forecast area Saturday
into early Sunday. However, the European and Canadian models are not
buying into this solution at the moment. As a result, will watch
this potential for the next several forecast runs before introducing
a mention of heavy rain.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
ISSUED AT 1137 PM CDT MON SEP 15 2014

Precip has departed well to the southeast of all terminal sites,
with clearing of the clouds expected to reach PIA by 05z and
progressing to CMI/DEC around 0730z. Still expect some fog
formation after the clearing develops, with a few areas developing
VLIFR ceilings and fog. A bit of a tough call on timing and
coverage of any dense fog, but for now BMI and CMI were the only
two locations with LIFR/VLIFR conditions between 11z-13z. The
latest HRRR keeps low vis east of CMI, with lingering low clouds
after midnight at all sites by PIA. It is possible that a stratus
layer forms instead of ground fog, but will lean toward fog
formation with this set of TAFs.

Skies should clear out quickly Tues morning with very dry air
above the shallow layer of moisture. Clear skies will continue
through the remainder of the TAF period to 06z/16.

Winds have become N behind the departing cold front, with a brief
increase in wind speeds to 10-12kt. Light winds should prevail the
remainder of the night and into Tuesday, as high pressure keeps
the pressure gradient weak.

&&

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

$$

UPDATE...SHIMON
SHORT TERM...HJS
LONG TERM...MILLER
AVIATION...SHIMON







000
FXUS63 KILX 160438
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1138 PM CDT Mon Sep 15 2014

.UPDATE...
ISSUED AT 900 PM CDT MON SEP 15 2014

Showers and drizzle are departing quickly to the southeast, with
the back edge of the clouds approaching faster than previously
expected as well. The latest HRRR is indicating a band of low
clouds are expected to redevelop behind the clearing, moving into
our counties from the northeast toward Lake Michigan. Low level
wind patterns and obs from that area show some support for that
solution. Have updated the sky grids to acknowledge both the
initial clearing and subsequent clouds from the NE for a few hours
after. Any areas that clear out will have a good chance of seeing
fog develop. The light winds later tonight could set the stage for
locally dense fog, especially NW of I-55 where clearing will
develop sooner. Dewpoints will remain relatively high for enough
hours after clearing that lows will drop very close to the
dewpoint in those areas. Added fog to the weather grids
accordingly. Updated info is already available.

&&

.SHORT TERM...(Tonight)
ISSUED AT 321 PM CDT MON SEP 15 2014

Storm system still impacting Central Illinois ahead of an
approaching boundary.  Some low clouds and developing fog in the
wake of the showers hint to the main issues going into the overnight
hours tonight.  Showers and thunderstorms should begin to wrap up
this evening but wet, misty, and low clouds should continue for a
little while at least.  Satellite imagery showing the low clouds
hanging around a bit after the wind shift/boundary moves through
with the NW/N winds.  Cooler tonight...but coolest in the NW where
most likely to see some clearing.  Temps may bottom out locally if
the cigs clear in the overnight.  Either way, enhanced llvl moisture
will bring with it the chance for fog development.  For now,
question is between dense fog and very low stratus.  Stratus already
developing and see no reason to break that trend, so only putting in
patchy fog mention in the overnight hours.

&&

.LONG TERM...(Tuesday through Monday)
ISSUED AT 321 PM CDT MON SEP 15 2014

The medium and long range models are in generally good agreement
that a progressive upper level flow pattern will dominate through
the next seven days.

Surface high pressure from the northern Plains will work its way
toward the Midwest Tuesday, resulting in a clearing sky and a
continuation of cooler than normal temperatures. A weak shortwave
trough in the upper level northwest flow will approach the
mid-Mississippi River valley Wednesday. However, an abundance of dry
air in the lower levels should keep central and eastern IL
rain-free. Would not be surprised to see a sprinkle or two in areas
southwest of a Rushville-Springfield line. Will hold off on the
mention of that for now as the favorable moisture and lift appears
to stay along and west of the MS River.

Anticyclonic low level flow will continue to dominate through
Thursday and Friday keeping rain out of the forecast. A return,
southerly flow Friday will finally allow temperatures to climb
toward seasonal levels in the 75-80 range across most of central and
southeast IL.

Will keep the potential for showers and thunderstorms in the
forecast west of I-57 Saturday, and across all of central and
eastern IL Saturday night. The European and GFS models are actually
in quite good agreement that an upper level trough will advance from
the Rockies Friday to the Midwest later Saturday. The southerly low
level flow will advect plenty of moisture ahead of the surface cold
front, resulting in showers and thunderstorms. However, there is the
potential for heavy rain from this system, particularly according to
the GFS solution. The GFS depicts the remnants of Hurricane Odile,
currently in the southern California Baja region, ejecting toward
the central U.S. with deep tropical moisture. This would easily
result in 1-3" of rain across much of the forecast area Saturday
into early Sunday. However, the European and Canadian models are not
buying into this solution at the moment. As a result, will watch
this potential for the next several forecast runs before introducing
a mention of heavy rain.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
ISSUED AT 1137 PM CDT MON SEP 15 2014

Precip has departed well to the southeast of all terminal sites,
with clearing of the clouds expected to reach PIA by 05z and
progressing to CMI/DEC around 0730z. Still expect some fog
formation after the clearing develops, with a few areas developing
VLIFR ceilings and fog. A bit of a tough call on timing and
coverage of any dense fog, but for now BMI and CMI were the only
two locations with LIFR/VLIFR conditions between 11z-13z. The
latest HRRR keeps low vis east of CMI, with lingering low clouds
after midnight at all sites by PIA. It is possible that a stratus
layer forms instead of ground fog, but will lean toward fog
formation with this set of TAFs.

Skies should clear out quickly Tues morning with very dry air
above the shallow layer of moisture. Clear skies will continue
through the remainder of the TAF period to 06z/16.

Winds have become N behind the departing cold front, with a brief
increase in wind speeds to 10-12kt. Light winds should prevail the
remainder of the night and into Tuesday, as high pressure keeps
the pressure gradient weak.

&&

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

$$

UPDATE...SHIMON
SHORT TERM...HJS
LONG TERM...MILLER
AVIATION...SHIMON






000
FXUS63 KLOT 160304
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1004 PM CDT MON SEP 15 2014

.DISCUSSION...
221 PM CDT

TONIGHT...
FRONTAL BOUNDARY THIS AFTERNOON CONTINUES TO SLIDE SOUTHEAST ACROSS
THE FORECAST AREA. VISIBLE IMAGERY ALONG AND JUST AHEAD OF THE
BOUNDARY INDICATED SOME VERTICAL GROWTH TO THE CLOUDS...SUGGESTIVE
OF SOME INSTABILITY. THERE HAS BEEN SOME SPOTTY CONVECTION ACROSS
NORTHEAST MO STRETCHING EAST THROUGH IL/CENTRAL IN BUT SOUTH OF THE
CWFA. DESPITE CONSIDERABLE SOLAR SHIELDING HAS BEEN ABLE TO KEEP
TEMPS IN THE 50S...WITH A FEW LOCATIONS BEING ABLE TO NUDGE TO ARND
60. WINDS WILL SHIFT NORTHWEST/NORTH BEHIND THE BOUNDARY WITH MUCH
DRIER/COOLER AIR STEADILY FILTERING INTO THE REGION OVERNIGHT.
PRECIP WILL COME TO AN END LATER THIS AFTN/EARLY EVE...WITH JUST A
FEW LINGERING SHOWERS ALONG AND EAST OF GIBSON CITY TO FOWLER. TEMPS
OVERNIGHT WILL COOL INTO THE LOW/MID 40S...WITH A FEW OF THE
TRADITIONALLY COOL SPOTS POSSIBLY DIPPING INTO THE UPR 30S BEFORE
DAYBREAK TUE. MEANWHILE CLOSER TO DOWNTOWN CHICAGO...THE URBAN HEAT
ISLAND SHUD AID IN KEEPING TEMPS IN THE UPR 40S TO ARND 50. THE ONLY
WILDCARD FOR OVERNIGHT LOWS WILL BE SKY COVER/WINDS...WHICH WITH
HIGH PRESSURE BUILDING IN SHUD ERODE/DIMINISH.

THERE IS ALSO SOME CONCERN THAT WITH THE LACK MIXING THIS AFTN AND
EXPECTED TEMPS BEING COOLER THAN AFTN DEW PTS...COUPLED WITH LIGHT
WINDS...COULD POINT TOWARDS PATCHY FOG DEVELOPING AWAY FROM THE
METRO AREA.

TUESDAY THROUGH THURSDAY...
RATHER BENIGN PATTERN FOR A GOOD PORTION OF THE WEEK. BROAD
ANTI-CYCLONIC FLOW WILL BUILD INTO THE REGION TUESDAY...WITH THE
MID-LVL TROUGH PIVOTING EAST. THE LONGWAVE PATTERN WILL LIKELY KEEP
THE REGION IN A CONTINUED NORTHWEST FLOW AS MID-LVL RIDGING RETURNS
TO THE WESTERN CONUS. GUIDANCE SUGGESTS THE SFC RIDGE THAT ARRIVES
TUE WILL SHIFT EAST...HOWEVER ANOTHER DOME OF HIGH PRESSURE FROM
CANADA IS THEN POISED TO SLIDE SOUTH AND CONTINUE THE DRY/COOL
WEATHER WED/THUR. TEMPS WILL GENERALLY REMAIN IN THE MID/UPR
60S...BUT POSSIBLY REACH 70 DEG IN SEVERAL AREAS FOR THUR. ABUNDANT
SUNSHINE IS EXPECTED EACH OF THE NEXT SEVERAL DAYS AS WELL.
OVERNIGHT LOWS WILL ALSO DIP INTO THE 40S TUE NGT/WED NGT...THEN
WITH THE SFC RIDGE BEGINNING TO PUSH EAST THUR NGT TEMPS COULD HOLD
ARND 50.

CONFIDENCE...HIGH.

FRIDAY THROUGH SUNDAY...
WITH THE SFC RIDGE POISED TO PUSH EAST OF THE REGION FRI...FLOW WILL
BE TURNING SOUTHERLY AND THE MID-LVL WAVE STARTING TO FLATTEN.
ENSEMBLES CONTINUE TO SHOW CONSIDERABLE SPREAD ON TIMING OF
PRECIP/MOISTURE RETURNING...WITH MOST MEMBERS POINTING TOWARDS FRI
NGT. THE ATMOSPHERE WILL MODERATE BY FRI/SAT WITH TEMPS IN THE
MID/UPR 70S...OR MORE SEASONAL. SAT APPEARS TO BE THE MOST FAVORABLE
PERIOD TO SEE SPOTTY SHOWERS/THUNDERSTORMS AS A MID-LVL TROUGH
DEVELOPS OVER THE CENTRAL PLAINS AND NEARS THE REGION SAT AFTN/EVE.
THEN FOR THE SECOND HALF OF THE WEEKEND SFC RIDGING IS PROGGED TO
RETURN TO THE REGION.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* LIGHT WEST TO NORTHWEST WINDS TUESDAY. LAKE BREEZE EXPECTED TO
  STAY TO THE EAST.

MDB

//DISCUSSION...UPDATED 03Z...

CLOUDS CONTINUE TO EXIT TO THE SOUTH WITH SKIES AT GYY BEING THE
MAIN CHALLENGE OVERNIGHT. SATELLITE DOES SHOW A NARROW BAND OF
LAKE STRATUS OFF THE SE WI AND NE IL SHORE LINE. WILL CONTINUE
WITH MVFR CIGS AT GYY INTO THE OVERNIGHT WITH THE IDEA THAT THE
CLOUD BAND WOULD SHIFT JUST TO THE EAST OVERNIGHT. CLOUD BASE
HEIGHT MAY NEED ADJUSTMENT AS WELL BUT TEMP-DEWPOINT SPREADS OVER
THE LAKE AND FORECAST SOUNDINGS SUGGEST 1500-2000 FT. NOT OVERLY
CONFIDENT IN THE DURATION OF CIGS THOUGH. THE OTHER CHALLENGE WILL
BE PATCHY FOG POTENTIAL OVERNIGHT...ESPECIALLY AT RFD/DPA. WILL
CONTINUE WITH BCFG AND TEMPO MVFR VSBY FOR NOW.

FROM 00Z...

FRONTAL BOUNDARY IS NOW APPROACHING MDW AND WILL PASS GYY EARLY
THIS EVENING TURNING WINDS NORTHERLY WITH AN INITIAL INCREASE IN
SPEED TO 10-15 KT. SPEEDS WILL SETTLE UNDER 10 KT THROUGH EARLY
EVENING BEHIND THE FRONT THOUGH GYY MAY KEEP SPEEDS ABOVE 10 KT
INTO MID EVENING. SATELLITE SHOWS THE BACK EDGE OF THE MAIN CLOUD
SHIELD MOVING QUICKLY SOUTHEAST WITH THE DIURNAL STRATO CU TO THE
NORTHWEST QUICKLY DISSIPATING. EXPECT SKIES TO CLEAR BY MID
EVENING ACROSS THE IL TERMINALS WITH LAKE EFFECT PROCESSES
POTENTIALLY KEEPING MVFR CLOUDS AT GYY INTO THE OVERNIGHT. SOME
RESIDUAL LOW LEVEL MOISTURE MAY ALLOW FOR SOME PATCHY OR SHALLOW
FOG OVERNIGHT AT RFD/DPA AS WINDS DIMINISH. NORTHWEST WINDS WILL
BECOME WESTERLY UNDER 10 KT AT THE IL TERMINALS TUESDAY. A LAKE
BREEZE WILL LIKELY DEVELOP BY MIDDAY BRINGING NE WINDS TO GYY BUT
THE INLAND PUSH LOOKS TO BE SLOW GIVEN THE MINIMAL LAKE-LAND TEMP
DIFFERENCE SO WILL KEEP IT EAST OF ORD/MDW FOR NOW. SOME SCATTERED
STRATO CU IS EXPECTED TO DEVELOP LATE MORNING THEN LIFT/DISSIPATE
THROUGH THE AFTERNOON.

MDB

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

* HIGH CONFIDENCE IN WEST TO NORTHWEST WINDS TUESDAY. MEDIUM-HIGH
  CONFIDENCE ANY LAKE BREEZE WILL REMAIN EAST.

MDB

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

WEDNESDAY...VFR. LIGHT WEST WINDS. LAKE BREEZE POSSIBLE.

THURSDAY...VFR. EAST WINDS.

FRIDAY...VFR. BREEZY SOUTH WINDS.

SATURDAY...CHANCE TSRA. MVFR POSSIBLE. BREEZY SOUTHWEST WINDS.

SUNDAY...SLIGHT CHANCE TSRA. VFR. WEST WINDS.

MDB

&&

.MARINE...
246 PM CDT

WEAK LOW PRESSURE WILL PUSH EAST THROUGH THE OHIO VALLEY AND
DISSIPATE THIS EVENING AS HIGH PRESSURE MOVES INTO THE MID
MISSOURI VALLEY TONIGHT. AHEAD OF THE HIGH A WEAK COLD FRONT WILL
SPREAD DOWN THE REMAINDER OF THE LAKE THIS EVENING AND BRIEFLY
INCREASE NORTH WINDS TO NEAR 20 KT THE HIGH WILL WEAKEN AND MOVE
OVER LAKE MICHIGAN ON TUESDAY. LOW PRESSURE OVER HUDSON BAY WILL
SPREAD INTO QUEBEC ON WEDNESDAY AS HIGH PRESSURE PUSHES SOUTH OUT
OF NORTHERN MANITOBA. AHEAD OF THE HIGH THE SOUTHWEST GRADIENT
INCREASES WITH WINDS 15 TO 25 KT FOR THE NORTH HALF OF THE LAKE. THE
HIGH REACHES LAKE SUPERIOR THURSDAY EVENING AND WILL PUSH A COLD
FRONT DOWN THE LAKE THURSDAY NIGHT. THIS HIGH WILL THEN MOVE TO
THE EASTERN LAKES BY LATE THURSDAY INTO FRIDAY AS SEVERAL LOWS
ORGANIZE IN THE CENTRAL PLAINS AND CANADIAN PRAIRIES.

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 160304
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1004 PM CDT MON SEP 15 2014

.DISCUSSION...
221 PM CDT

TONIGHT...
FRONTAL BOUNDARY THIS AFTERNOON CONTINUES TO SLIDE SOUTHEAST ACROSS
THE FORECAST AREA. VISIBLE IMAGERY ALONG AND JUST AHEAD OF THE
BOUNDARY INDICATED SOME VERTICAL GROWTH TO THE CLOUDS...SUGGESTIVE
OF SOME INSTABILITY. THERE HAS BEEN SOME SPOTTY CONVECTION ACROSS
NORTHEAST MO STRETCHING EAST THROUGH IL/CENTRAL IN BUT SOUTH OF THE
CWFA. DESPITE CONSIDERABLE SOLAR SHIELDING HAS BEEN ABLE TO KEEP
TEMPS IN THE 50S...WITH A FEW LOCATIONS BEING ABLE TO NUDGE TO ARND
60. WINDS WILL SHIFT NORTHWEST/NORTH BEHIND THE BOUNDARY WITH MUCH
DRIER/COOLER AIR STEADILY FILTERING INTO THE REGION OVERNIGHT.
PRECIP WILL COME TO AN END LATER THIS AFTN/EARLY EVE...WITH JUST A
FEW LINGERING SHOWERS ALONG AND EAST OF GIBSON CITY TO FOWLER. TEMPS
OVERNIGHT WILL COOL INTO THE LOW/MID 40S...WITH A FEW OF THE
TRADITIONALLY COOL SPOTS POSSIBLY DIPPING INTO THE UPR 30S BEFORE
DAYBREAK TUE. MEANWHILE CLOSER TO DOWNTOWN CHICAGO...THE URBAN HEAT
ISLAND SHUD AID IN KEEPING TEMPS IN THE UPR 40S TO ARND 50. THE ONLY
WILDCARD FOR OVERNIGHT LOWS WILL BE SKY COVER/WINDS...WHICH WITH
HIGH PRESSURE BUILDING IN SHUD ERODE/DIMINISH.

THERE IS ALSO SOME CONCERN THAT WITH THE LACK MIXING THIS AFTN AND
EXPECTED TEMPS BEING COOLER THAN AFTN DEW PTS...COUPLED WITH LIGHT
WINDS...COULD POINT TOWARDS PATCHY FOG DEVELOPING AWAY FROM THE
METRO AREA.

TUESDAY THROUGH THURSDAY...
RATHER BENIGN PATTERN FOR A GOOD PORTION OF THE WEEK. BROAD
ANTI-CYCLONIC FLOW WILL BUILD INTO THE REGION TUESDAY...WITH THE
MID-LVL TROUGH PIVOTING EAST. THE LONGWAVE PATTERN WILL LIKELY KEEP
THE REGION IN A CONTINUED NORTHWEST FLOW AS MID-LVL RIDGING RETURNS
TO THE WESTERN CONUS. GUIDANCE SUGGESTS THE SFC RIDGE THAT ARRIVES
TUE WILL SHIFT EAST...HOWEVER ANOTHER DOME OF HIGH PRESSURE FROM
CANADA IS THEN POISED TO SLIDE SOUTH AND CONTINUE THE DRY/COOL
WEATHER WED/THUR. TEMPS WILL GENERALLY REMAIN IN THE MID/UPR
60S...BUT POSSIBLY REACH 70 DEG IN SEVERAL AREAS FOR THUR. ABUNDANT
SUNSHINE IS EXPECTED EACH OF THE NEXT SEVERAL DAYS AS WELL.
OVERNIGHT LOWS WILL ALSO DIP INTO THE 40S TUE NGT/WED NGT...THEN
WITH THE SFC RIDGE BEGINNING TO PUSH EAST THUR NGT TEMPS COULD HOLD
ARND 50.

CONFIDENCE...HIGH.

FRIDAY THROUGH SUNDAY...
WITH THE SFC RIDGE POISED TO PUSH EAST OF THE REGION FRI...FLOW WILL
BE TURNING SOUTHERLY AND THE MID-LVL WAVE STARTING TO FLATTEN.
ENSEMBLES CONTINUE TO SHOW CONSIDERABLE SPREAD ON TIMING OF
PRECIP/MOISTURE RETURNING...WITH MOST MEMBERS POINTING TOWARDS FRI
NGT. THE ATMOSPHERE WILL MODERATE BY FRI/SAT WITH TEMPS IN THE
MID/UPR 70S...OR MORE SEASONAL. SAT APPEARS TO BE THE MOST FAVORABLE
PERIOD TO SEE SPOTTY SHOWERS/THUNDERSTORMS AS A MID-LVL TROUGH
DEVELOPS OVER THE CENTRAL PLAINS AND NEARS THE REGION SAT AFTN/EVE.
THEN FOR THE SECOND HALF OF THE WEEKEND SFC RIDGING IS PROGGED TO
RETURN TO THE REGION.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* LIGHT WEST TO NORTHWEST WINDS TUESDAY. LAKE BREEZE EXPECTED TO
  STAY TO THE EAST.

MDB

//DISCUSSION...UPDATED 03Z...

CLOUDS CONTINUE TO EXIT TO THE SOUTH WITH SKIES AT GYY BEING THE
MAIN CHALLENGE OVERNIGHT. SATELLITE DOES SHOW A NARROW BAND OF
LAKE STRATUS OFF THE SE WI AND NE IL SHORE LINE. WILL CONTINUE
WITH MVFR CIGS AT GYY INTO THE OVERNIGHT WITH THE IDEA THAT THE
CLOUD BAND WOULD SHIFT JUST TO THE EAST OVERNIGHT. CLOUD BASE
HEIGHT MAY NEED ADJUSTMENT AS WELL BUT TEMP-DEWPOINT SPREADS OVER
THE LAKE AND FORECAST SOUNDINGS SUGGEST 1500-2000 FT. NOT OVERLY
CONFIDENT IN THE DURATION OF CIGS THOUGH. THE OTHER CHALLENGE WILL
BE PATCHY FOG POTENTIAL OVERNIGHT...ESPECIALLY AT RFD/DPA. WILL
CONTINUE WITH BCFG AND TEMPO MVFR VSBY FOR NOW.

FROM 00Z...

FRONTAL BOUNDARY IS NOW APPROACHING MDW AND WILL PASS GYY EARLY
THIS EVENING TURNING WINDS NORTHERLY WITH AN INITIAL INCREASE IN
SPEED TO 10-15 KT. SPEEDS WILL SETTLE UNDER 10 KT THROUGH EARLY
EVENING BEHIND THE FRONT THOUGH GYY MAY KEEP SPEEDS ABOVE 10 KT
INTO MID EVENING. SATELLITE SHOWS THE BACK EDGE OF THE MAIN CLOUD
SHIELD MOVING QUICKLY SOUTHEAST WITH THE DIURNAL STRATO CU TO THE
NORTHWEST QUICKLY DISSIPATING. EXPECT SKIES TO CLEAR BY MID
EVENING ACROSS THE IL TERMINALS WITH LAKE EFFECT PROCESSES
POTENTIALLY KEEPING MVFR CLOUDS AT GYY INTO THE OVERNIGHT. SOME
RESIDUAL LOW LEVEL MOISTURE MAY ALLOW FOR SOME PATCHY OR SHALLOW
FOG OVERNIGHT AT RFD/DPA AS WINDS DIMINISH. NORTHWEST WINDS WILL
BECOME WESTERLY UNDER 10 KT AT THE IL TERMINALS TUESDAY. A LAKE
BREEZE WILL LIKELY DEVELOP BY MIDDAY BRINGING NE WINDS TO GYY BUT
THE INLAND PUSH LOOKS TO BE SLOW GIVEN THE MINIMAL LAKE-LAND TEMP
DIFFERENCE SO WILL KEEP IT EAST OF ORD/MDW FOR NOW. SOME SCATTERED
STRATO CU IS EXPECTED TO DEVELOP LATE MORNING THEN LIFT/DISSIPATE
THROUGH THE AFTERNOON.

MDB

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

* HIGH CONFIDENCE IN WEST TO NORTHWEST WINDS TUESDAY. MEDIUM-HIGH
  CONFIDENCE ANY LAKE BREEZE WILL REMAIN EAST.

MDB

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

WEDNESDAY...VFR. LIGHT WEST WINDS. LAKE BREEZE POSSIBLE.

THURSDAY...VFR. EAST WINDS.

FRIDAY...VFR. BREEZY SOUTH WINDS.

SATURDAY...CHANCE TSRA. MVFR POSSIBLE. BREEZY SOUTHWEST WINDS.

SUNDAY...SLIGHT CHANCE TSRA. VFR. WEST WINDS.

MDB

&&

.MARINE...
246 PM CDT

WEAK LOW PRESSURE WILL PUSH EAST THROUGH THE OHIO VALLEY AND
DISSIPATE THIS EVENING AS HIGH PRESSURE MOVES INTO THE MID
MISSOURI VALLEY TONIGHT. AHEAD OF THE HIGH A WEAK COLD FRONT WILL
SPREAD DOWN THE REMAINDER OF THE LAKE THIS EVENING AND BRIEFLY
INCREASE NORTH WINDS TO NEAR 20 KT THE HIGH WILL WEAKEN AND MOVE
OVER LAKE MICHIGAN ON TUESDAY. LOW PRESSURE OVER HUDSON BAY WILL
SPREAD INTO QUEBEC ON WEDNESDAY AS HIGH PRESSURE PUSHES SOUTH OUT
OF NORTHERN MANITOBA. AHEAD OF THE HIGH THE SOUTHWEST GRADIENT
INCREASES WITH WINDS 15 TO 25 KT FOR THE NORTH HALF OF THE LAKE. THE
HIGH REACHES LAKE SUPERIOR THURSDAY EVENING AND WILL PUSH A COLD
FRONT DOWN THE LAKE THURSDAY NIGHT. THIS HIGH WILL THEN MOVE TO
THE EASTERN LAKES BY LATE THURSDAY INTO FRIDAY AS SEVERAL LOWS
ORGANIZE IN THE CENTRAL PLAINS AND CANADIAN PRAIRIES.

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 160207 CCA
AFDILX

Area Forecast Discussion...Corrected format
NATIONAL WEATHER SERVICE LINCOLN IL
907 PM CDT Mon Sep 15 2014

.UPDATE...
ISSUED AT 900 PM CDT MON SEP 15 2014

Showers and drizzle are departing quickly to the southeast, with
the back edge of the clouds approaching faster than previously
expected as well. The latest HRRR is indicating a band of low
clouds are expected to redevelop behind the clearing, moving into
our counties from the northeast toward Lake Michigan. Low level
wind patterns and obs from that area show some support for that
solution. Have updated the sky grids to acknowledge both the
initial clearing and subsequent clouds from the NE for a few hours
after. Any areas that clear out will have a good chance of seeing
fog develop. The light winds later tonight could set the stage for
locally dense fog, especially NW of I-55 where clearing will
develop sooner. Dewpoints will remain relatively high for enough
hours after clearing that lows will drop very close to the
dewpoint in those areas. Added fog to the weather grids
accordingly. Updated info is already available.

&&

.SHORT TERM...(Tonight)
ISSUED AT 321 PM CDT MON SEP 15 2014

Storm system still impacting Central Illinois ahead of an
approaching boundary.  Some low clouds and developing fog in the
wake of the showers hint to the main issues going into the overnight
hours tonight.  Showers and thunderstorms should begin to wrap up
this evening but wet, misty, and low clouds should continue for a
little while at least.  Satellite imagery showing the low clouds
hanging around a bit after the wind shift/boundary moves through
with the NW/N winds.  Cooler tonight...but coolest in the NW where
most likely to see some clearing.  Temps may bottom out locally if
the cigs clear in the overnight.  Either way, enhanced llvl moisture
will bring with it the chance for fog development.  For now,
question is between dense fog and very low stratus.  Stratus already
developing and see no reason to break that trend, so only putting in
patchy fog mention in the overnight hours.

&&

.LONG TERM...(Tuesday through Monday)
ISSUED AT 321 PM CDT MON SEP 15 2014

The medium and long range models are in generally good agreement
that a progressive upper level flow pattern will dominate through
the next seven days.

Surface high pressure from the northern Plains will work its way
toward the Midwest Tuesday, resulting in a clearing sky and a
continuation of cooler than normal temperatures. A weak shortwave
trough in the upper level northwest flow will approach the
mid-Mississippi River valley Wednesday. However, an abundance of dry
air in the lower levels should keep central and eastern IL
rain-free. Would not be surprised to see a sprinkle or two in areas
southwest of a Rushville-Springfield line. Will hold off on the
mention of that for now as the favorable moisture and lift appears
to stay along and west of the MS River.

Anticyclonic low level flow will continue to dominate through
Thursday and Friday keeping rain out of the forecast. A return,
southerly flow Friday will finally allow temperatures to climb
toward seasonal levels in the 75-80 range across most of central and
southeast IL.

Will keep the potential for showers and thunderstorms in the
forecast west of I-57 Saturday, and across all of central and
eastern IL Saturday night. The European and GFS models are actually
in quite good agreement that an upper level trough will advance from
the Rockies Friday to the Midwest later Saturday. The southerly low
level flow will advect plenty of moisture ahead of the surface cold
front, resulting in showers and thunderstorms. However, there is the
potential for heavy rain from this system, particularly according to
the GFS solution. The GFS depicts the remnants of Hurricane Odile,
currently in the southern California Baja region, ejecting toward
the central U.S. with deep tropical moisture. This would easily
result in 1-3" of rain across much of the forecast area Saturday
into early Sunday. However, the European and Canadian models are not
buying into this solution at the moment. As a result, will watch
this potential for the next several forecast runs before introducing
a mention of heavy rain.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 700 PM CDT MON SEP 15 2014

Showers and/or drizzle will linger for another hour or two at the
terminal sites except PIA, which is seeing ceiling heights rise to
VFR periodically due to dry air mixing down already. Satellite and
observations are indicating MVFR will return to PIA for several
more hours before some clearing arrives. CMI is the only LIFR
site, with IFR at SPI/BMI/DEC due to low cigs and vis. Forecast
soundings and HRRR output still show progressively improving
conditions by late evening, with high pressure building behind the
departing cold front. Therefore, have kept the clearing trends in
the cloud cover, with fog formation likely in any areas that clear
out. Went LIFR or VLIFR fog FROM 11Z-13Z for the northern
terminals of PIA/BMI/CMI, and IFR at SPI/DEC. The timing may need
to be adjusted, but feeling more confident that low level moisture
will become low stratus and fog across the board.

VFR conditions should develop quickly Tuesday morning with mixing
of very dry air just above the moisture layer.

Any residual WNW winds will become N by late evening behind the
front. A few gusts to 18kt will be possible for an hour or two
past FROPA, then light winds should develop the rest of the night
and into Tuesday.

&&

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

$$

UPDATE...SHIMON
SHORT TERM...HJS
LONG TERM...MILLER
AVIATION...SHIMON









000
FXUS63 KILX 160207 CCA
AFDILX

Area Forecast Discussion...Corrected format
NATIONAL WEATHER SERVICE LINCOLN IL
907 PM CDT Mon Sep 15 2014

.UPDATE...
ISSUED AT 900 PM CDT MON SEP 15 2014

Showers and drizzle are departing quickly to the southeast, with
the back edge of the clouds approaching faster than previously
expected as well. The latest HRRR is indicating a band of low
clouds are expected to redevelop behind the clearing, moving into
our counties from the northeast toward Lake Michigan. Low level
wind patterns and obs from that area show some support for that
solution. Have updated the sky grids to acknowledge both the
initial clearing and subsequent clouds from the NE for a few hours
after. Any areas that clear out will have a good chance of seeing
fog develop. The light winds later tonight could set the stage for
locally dense fog, especially NW of I-55 where clearing will
develop sooner. Dewpoints will remain relatively high for enough
hours after clearing that lows will drop very close to the
dewpoint in those areas. Added fog to the weather grids
accordingly. Updated info is already available.

&&

.SHORT TERM...(Tonight)
ISSUED AT 321 PM CDT MON SEP 15 2014

Storm system still impacting Central Illinois ahead of an
approaching boundary.  Some low clouds and developing fog in the
wake of the showers hint to the main issues going into the overnight
hours tonight.  Showers and thunderstorms should begin to wrap up
this evening but wet, misty, and low clouds should continue for a
little while at least.  Satellite imagery showing the low clouds
hanging around a bit after the wind shift/boundary moves through
with the NW/N winds.  Cooler tonight...but coolest in the NW where
most likely to see some clearing.  Temps may bottom out locally if
the cigs clear in the overnight.  Either way, enhanced llvl moisture
will bring with it the chance for fog development.  For now,
question is between dense fog and very low stratus.  Stratus already
developing and see no reason to break that trend, so only putting in
patchy fog mention in the overnight hours.

&&

.LONG TERM...(Tuesday through Monday)
ISSUED AT 321 PM CDT MON SEP 15 2014

The medium and long range models are in generally good agreement
that a progressive upper level flow pattern will dominate through
the next seven days.

Surface high pressure from the northern Plains will work its way
toward the Midwest Tuesday, resulting in a clearing sky and a
continuation of cooler than normal temperatures. A weak shortwave
trough in the upper level northwest flow will approach the
mid-Mississippi River valley Wednesday. However, an abundance of dry
air in the lower levels should keep central and eastern IL
rain-free. Would not be surprised to see a sprinkle or two in areas
southwest of a Rushville-Springfield line. Will hold off on the
mention of that for now as the favorable moisture and lift appears
to stay along and west of the MS River.

Anticyclonic low level flow will continue to dominate through
Thursday and Friday keeping rain out of the forecast. A return,
southerly flow Friday will finally allow temperatures to climb
toward seasonal levels in the 75-80 range across most of central and
southeast IL.

Will keep the potential for showers and thunderstorms in the
forecast west of I-57 Saturday, and across all of central and
eastern IL Saturday night. The European and GFS models are actually
in quite good agreement that an upper level trough will advance from
the Rockies Friday to the Midwest later Saturday. The southerly low
level flow will advect plenty of moisture ahead of the surface cold
front, resulting in showers and thunderstorms. However, there is the
potential for heavy rain from this system, particularly according to
the GFS solution. The GFS depicts the remnants of Hurricane Odile,
currently in the southern California Baja region, ejecting toward
the central U.S. with deep tropical moisture. This would easily
result in 1-3" of rain across much of the forecast area Saturday
into early Sunday. However, the European and Canadian models are not
buying into this solution at the moment. As a result, will watch
this potential for the next several forecast runs before introducing
a mention of heavy rain.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 700 PM CDT MON SEP 15 2014

Showers and/or drizzle will linger for another hour or two at the
terminal sites except PIA, which is seeing ceiling heights rise to
VFR periodically due to dry air mixing down already. Satellite and
observations are indicating MVFR will return to PIA for several
more hours before some clearing arrives. CMI is the only LIFR
site, with IFR at SPI/BMI/DEC due to low cigs and vis. Forecast
soundings and HRRR output still show progressively improving
conditions by late evening, with high pressure building behind the
departing cold front. Therefore, have kept the clearing trends in
the cloud cover, with fog formation likely in any areas that clear
out. Went LIFR or VLIFR fog FROM 11Z-13Z for the northern
terminals of PIA/BMI/CMI, and IFR at SPI/DEC. The timing may need
to be adjusted, but feeling more confident that low level moisture
will become low stratus and fog across the board.

VFR conditions should develop quickly Tuesday morning with mixing
of very dry air just above the moisture layer.

Any residual WNW winds will become N by late evening behind the
front. A few gusts to 18kt will be possible for an hour or two
past FROPA, then light winds should develop the rest of the night
and into Tuesday.

&&

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

$$

UPDATE...SHIMON
SHORT TERM...HJS
LONG TERM...MILLER
AVIATION...SHIMON








000
FXUS63 KILX 160204
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
904 PM CDT Mon Sep 15 2014

.UPDATE...
ISSUED AT 900 PM CDT MON SEP 15 2014

Showers and drizzle are departing quickly to the southeast, with
the back edge of the clouds approaching faster than previously
expected as well. The latest HRRR is indicating a band of low
clouds are expected to redevelop behind the clearing, moving into
our counties from the northeast toward Lake Michigan. Low level
wind patterns and obs from that area show some support for that
solution. Have updated the sky grids to acknowledge both the
initial clearing and subsequent clouds from the NE for a few hours
after. Any areas that clear out will have a good chance of seeing
fog develop. The light winds later tonight could set the stage for
locally dense fog, especially NW of I-55 where clearing will
develop sooner. Dewpoints will remain relatively high for enough
hours after clearing that lows will drop very close to the
dewpoint in those areas. Added fog to the weather grids
accordingly. Updated info is already available.

&&

.SHORT TERM...(TONIGHT)
ISSUED AT 321 PM CDT MON SEP 15 2014

STORM SYSTEM STILL IMPACTING CENTRAL ILLINOIS AHEAD OF AN
APPROACHING BOUNDARY.  SOME LOW CLOUDS AND DEVELOPING FOG IN THE
WAKE OF THE SHOWERS HINT TO THE MAIN ISSUES GOING INTO THE OVERNIGHT
HOURS TONIGHT.  SHOWERS AND THUNDERSTORMS SHOULD BEGIN TO WRAP UP
THIS EVENING BUT WET, MISTY, AND LOW CLOUDS SHOULD CONTINUE FOR A
LITTLE WHILE AT LEAST.  SATELLITE IMAGERY SHOWING THE LOW CLOUDS
HANGING AROUND A BIT AFTER THE WIND SHIFT/BOUNDARY MOVES THROUGH
WITH THE NW/N WINDS.  COOLER TONIGHT...BUT COOLEST IN THE NW WHERE
MOST LIKELY TO SEE SOME CLEARING.  TEMPS MAY BOTTOM OUT LOCALLY IF
THE CIGS CLEAR IN THE OVERNIGHT.  EITHER WAY, ENHANCED LLVL MOISTURE
WILL BRING WITH IT THE CHANCE FOR FOG DEVELOPMENT.  FOR NOW,
QUESTION IS BETWEEN DENSE FOG AND VERY LOW STRATUS.  STRATUS ALREADY
DEVELOPING AND SEE NO REASON TO BREAK THAT TREND, SO ONLY PUTTING IN
PATCHY FOG MENTION IN THE OVERNIGHT HOURS.

&&

.LONG TERM...(TUESDAY THROUGH MONDAY)
ISSUED AT 321 PM CDT MON SEP 15 2014

THE MEDIUM AND LONG RANGE MODELS ARE IN GENERALLY GOOD AGREEMENT
THAT A PROGRESSIVE UPPER LEVEL FLOW PATTERN WILL DOMINATE THROUGH
THE NEXT SEVEN DAYS.

SURFACE HIGH PRESSURE FROM THE NORTHERN PLAINS WILL WORK ITS WAY
TOWARD THE MIDWEST TUESDAY, RESULTING IN A CLEARING SKY AND A
CONTINUATION OF COOLER THAN NORMAL TEMPERATURES. A WEAK SHORTWAVE
TROUGH IN THE UPPER LEVEL NORTHWEST FLOW WILL APPROACH THE
MID-MISSISSIPPI RIVER VALLEY WEDNESDAY. HOWEVER, AN ABUNDANCE OF DRY
AIR IN THE LOWER LEVELS SHOULD KEEP CENTRAL AND EASTERN IL
RAIN-FREE. WOULD NOT BE SURPRISED TO SEE A SPRINKLE OR TWO IN AREAS
SOUTHWEST OF A RUSHVILLE-SPRINGFIELD LINE. WILL HOLD OFF ON THE
MENTION OF THAT FOR NOW AS THE FAVORABLE MOISTURE AND LIFT APPEARS
TO STAY ALONG AND WEST OF THE MS RIVER.

ANTICYCLONIC LOW LEVEL FLOW WILL CONTINUE TO DOMINATE THROUGH
THURSDAY AND FRIDAY KEEPING RAIN OUT OF THE FORECAST. A RETURN,
SOUTHERLY FLOW FRIDAY WILL FINALLY ALLOW TEMPERATURES TO CLIMB
TOWARD SEASONAL LEVELS IN THE 75-80 RANGE ACROSS MOST OF CENTRAL AND
SOUTHEAST IL.

WILL KEEP THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS IN THE
FORECAST WEST OF I-57 SATURDAY, AND ACROSS ALL OF CENTRAL AND
EASTERN IL SATURDAY NIGHT. THE EUROPEAN AND GFS MODELS ARE ACTUALLY
IN QUITE GOOD AGREEMENT THAT AN UPPER LEVEL TROUGH WILL ADVANCE FROM
THE ROCKIES FRIDAY TO THE MIDWEST LATER SATURDAY. THE SOUTHERLY LOW
LEVEL FLOW WILL ADVECT PLENTY OF MOISTURE AHEAD OF THE SURFACE COLD
FRONT, RESULTING IN SHOWERS AND THUNDERSTORMS. HOWEVER, THERE IS THE
POTENTIAL FOR HEAVY RAIN FROM THIS SYSTEM, PARTICULARLY ACCORDING TO
THE GFS SOLUTION. THE GFS DEPICTS THE REMNANTS OF HURRICANE ODILE,
CURRENTLY IN THE SOUTHERN CALIFORNIA BAJA REGION, EJECTING TOWARD
THE CENTRAL U.S. WITH DEEP TROPICAL MOISTURE. THIS WOULD EASILY
RESULT IN 1-3" OF RAIN ACROSS MUCH OF THE FORECAST AREA SATURDAY
INTO EARLY SUNDAY. HOWEVER, THE EUROPEAN AND CANADIAN MODELS ARE NOT
BUYING INTO THIS SOLUTION AT THE MOMENT. AS A RESULT, WILL WATCH
THIS POTENTIAL FOR THE NEXT SEVERAL FORECAST RUNS BEFORE INTRODUCING
A MENTION OF HEAVY RAIN.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 700 PM CDT MON SEP 15 2014

SHOWERS AND/OR DRIZZLE WILL LINGER FOR ANOTHER HOUR OR TWO AT THE
TERMINAL SITES EXCEPT PIA, WHICH IS SEEING CEILING HEIGHTS RISE TO
VFR PERIODICALLY DUE TO DRY AIR MIXING DOWN ALREADY. SATELLITE AND
OBSERVATIONS ARE INDICATING MVFR WILL RETURN TO PIA FOR SEVERAL
MORE HOURS BEFORE SOME CLEARING ARRIVES. CMI IS THE ONLY LIFR
SITE, WITH IFR AT SPI/BMI/DEC DUE TO LOW CIGS AND VIS. FORECAST
SOUNDINGS AND HRRR OUTPUT STILL SHOW PROGRESSIVELY IMPROVING
CONDITIONS BY LATE EVENING, WITH HIGH PRESSURE BUILDING BEHIND THE
DEPARTING COLD FRONT. THEREFORE, HAVE KEPT THE CLEARING TRENDS IN
THE CLOUD COVER, WITH FOG FORMATION LIKELY IN ANY AREAS THAT CLEAR
OUT. WENT LIFR OR VLIFR FOG FROM 11Z-13Z FOR THE NORTHERN
TERMINALS OF PIA/BMI/CMI, AND IFR AT SPI/DEC. THE TIMING MAY NEED
TO BE ADJUSTED, BUT FEELING MORE CONFIDENT THAT LOW LEVEL MOISTURE
WILL BECOME LOW STRATUS AND FOG ACROSS THE BOARD.

VFR CONDITIONS SHOULD DEVELOP QUICKLY TUESDAY MORNING WITH MIXING
OF VERY DRY AIR JUST ABOVE THE MOISTURE LAYER.

ANY RESIDUAL WNW WINDS WILL BECOME N BY LATE EVENING BEHIND THE
FRONT. A FEW GUSTS TO 18KT WILL BE POSSIBLE FOR AN HOUR OR TWO
PAST FROPA, THEN LIGHT WINDS SHOULD DEVELOP THE REST OF THE NIGHT
AND INTO TUESDAY.


&&

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

$$

UPDATE...SHIMON
SHORT TERM...HJS
LONG TERM...MILLER
AVIATION...SHIMON







000
FXUS63 KILX 160204
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
904 PM CDT Mon Sep 15 2014

.UPDATE...
ISSUED AT 900 PM CDT MON SEP 15 2014

Showers and drizzle are departing quickly to the southeast, with
the back edge of the clouds approaching faster than previously
expected as well. The latest HRRR is indicating a band of low
clouds are expected to redevelop behind the clearing, moving into
our counties from the northeast toward Lake Michigan. Low level
wind patterns and obs from that area show some support for that
solution. Have updated the sky grids to acknowledge both the
initial clearing and subsequent clouds from the NE for a few hours
after. Any areas that clear out will have a good chance of seeing
fog develop. The light winds later tonight could set the stage for
locally dense fog, especially NW of I-55 where clearing will
develop sooner. Dewpoints will remain relatively high for enough
hours after clearing that lows will drop very close to the
dewpoint in those areas. Added fog to the weather grids
accordingly. Updated info is already available.

&&

.SHORT TERM...(TONIGHT)
ISSUED AT 321 PM CDT MON SEP 15 2014

STORM SYSTEM STILL IMPACTING CENTRAL ILLINOIS AHEAD OF AN
APPROACHING BOUNDARY.  SOME LOW CLOUDS AND DEVELOPING FOG IN THE
WAKE OF THE SHOWERS HINT TO THE MAIN ISSUES GOING INTO THE OVERNIGHT
HOURS TONIGHT.  SHOWERS AND THUNDERSTORMS SHOULD BEGIN TO WRAP UP
THIS EVENING BUT WET, MISTY, AND LOW CLOUDS SHOULD CONTINUE FOR A
LITTLE WHILE AT LEAST.  SATELLITE IMAGERY SHOWING THE LOW CLOUDS
HANGING AROUND A BIT AFTER THE WIND SHIFT/BOUNDARY MOVES THROUGH
WITH THE NW/N WINDS.  COOLER TONIGHT...BUT COOLEST IN THE NW WHERE
MOST LIKELY TO SEE SOME CLEARING.  TEMPS MAY BOTTOM OUT LOCALLY IF
THE CIGS CLEAR IN THE OVERNIGHT.  EITHER WAY, ENHANCED LLVL MOISTURE
WILL BRING WITH IT THE CHANCE FOR FOG DEVELOPMENT.  FOR NOW,
QUESTION IS BETWEEN DENSE FOG AND VERY LOW STRATUS.  STRATUS ALREADY
DEVELOPING AND SEE NO REASON TO BREAK THAT TREND, SO ONLY PUTTING IN
PATCHY FOG MENTION IN THE OVERNIGHT HOURS.

&&

.LONG TERM...(TUESDAY THROUGH MONDAY)
ISSUED AT 321 PM CDT MON SEP 15 2014

THE MEDIUM AND LONG RANGE MODELS ARE IN GENERALLY GOOD AGREEMENT
THAT A PROGRESSIVE UPPER LEVEL FLOW PATTERN WILL DOMINATE THROUGH
THE NEXT SEVEN DAYS.

SURFACE HIGH PRESSURE FROM THE NORTHERN PLAINS WILL WORK ITS WAY
TOWARD THE MIDWEST TUESDAY, RESULTING IN A CLEARING SKY AND A
CONTINUATION OF COOLER THAN NORMAL TEMPERATURES. A WEAK SHORTWAVE
TROUGH IN THE UPPER LEVEL NORTHWEST FLOW WILL APPROACH THE
MID-MISSISSIPPI RIVER VALLEY WEDNESDAY. HOWEVER, AN ABUNDANCE OF DRY
AIR IN THE LOWER LEVELS SHOULD KEEP CENTRAL AND EASTERN IL
RAIN-FREE. WOULD NOT BE SURPRISED TO SEE A SPRINKLE OR TWO IN AREAS
SOUTHWEST OF A RUSHVILLE-SPRINGFIELD LINE. WILL HOLD OFF ON THE
MENTION OF THAT FOR NOW AS THE FAVORABLE MOISTURE AND LIFT APPEARS
TO STAY ALONG AND WEST OF THE MS RIVER.

ANTICYCLONIC LOW LEVEL FLOW WILL CONTINUE TO DOMINATE THROUGH
THURSDAY AND FRIDAY KEEPING RAIN OUT OF THE FORECAST. A RETURN,
SOUTHERLY FLOW FRIDAY WILL FINALLY ALLOW TEMPERATURES TO CLIMB
TOWARD SEASONAL LEVELS IN THE 75-80 RANGE ACROSS MOST OF CENTRAL AND
SOUTHEAST IL.

WILL KEEP THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS IN THE
FORECAST WEST OF I-57 SATURDAY, AND ACROSS ALL OF CENTRAL AND
EASTERN IL SATURDAY NIGHT. THE EUROPEAN AND GFS MODELS ARE ACTUALLY
IN QUITE GOOD AGREEMENT THAT AN UPPER LEVEL TROUGH WILL ADVANCE FROM
THE ROCKIES FRIDAY TO THE MIDWEST LATER SATURDAY. THE SOUTHERLY LOW
LEVEL FLOW WILL ADVECT PLENTY OF MOISTURE AHEAD OF THE SURFACE COLD
FRONT, RESULTING IN SHOWERS AND THUNDERSTORMS. HOWEVER, THERE IS THE
POTENTIAL FOR HEAVY RAIN FROM THIS SYSTEM, PARTICULARLY ACCORDING TO
THE GFS SOLUTION. THE GFS DEPICTS THE REMNANTS OF HURRICANE ODILE,
CURRENTLY IN THE SOUTHERN CALIFORNIA BAJA REGION, EJECTING TOWARD
THE CENTRAL U.S. WITH DEEP TROPICAL MOISTURE. THIS WOULD EASILY
RESULT IN 1-3" OF RAIN ACROSS MUCH OF THE FORECAST AREA SATURDAY
INTO EARLY SUNDAY. HOWEVER, THE EUROPEAN AND CANADIAN MODELS ARE NOT
BUYING INTO THIS SOLUTION AT THE MOMENT. AS A RESULT, WILL WATCH
THIS POTENTIAL FOR THE NEXT SEVERAL FORECAST RUNS BEFORE INTRODUCING
A MENTION OF HEAVY RAIN.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 700 PM CDT MON SEP 15 2014

SHOWERS AND/OR DRIZZLE WILL LINGER FOR ANOTHER HOUR OR TWO AT THE
TERMINAL SITES EXCEPT PIA, WHICH IS SEEING CEILING HEIGHTS RISE TO
VFR PERIODICALLY DUE TO DRY AIR MIXING DOWN ALREADY. SATELLITE AND
OBSERVATIONS ARE INDICATING MVFR WILL RETURN TO PIA FOR SEVERAL
MORE HOURS BEFORE SOME CLEARING ARRIVES. CMI IS THE ONLY LIFR
SITE, WITH IFR AT SPI/BMI/DEC DUE TO LOW CIGS AND VIS. FORECAST
SOUNDINGS AND HRRR OUTPUT STILL SHOW PROGRESSIVELY IMPROVING
CONDITIONS BY LATE EVENING, WITH HIGH PRESSURE BUILDING BEHIND THE
DEPARTING COLD FRONT. THEREFORE, HAVE KEPT THE CLEARING TRENDS IN
THE CLOUD COVER, WITH FOG FORMATION LIKELY IN ANY AREAS THAT CLEAR
OUT. WENT LIFR OR VLIFR FOG FROM 11Z-13Z FOR THE NORTHERN
TERMINALS OF PIA/BMI/CMI, AND IFR AT SPI/DEC. THE TIMING MAY NEED
TO BE ADJUSTED, BUT FEELING MORE CONFIDENT THAT LOW LEVEL MOISTURE
WILL BECOME LOW STRATUS AND FOG ACROSS THE BOARD.

VFR CONDITIONS SHOULD DEVELOP QUICKLY TUESDAY MORNING WITH MIXING
OF VERY DRY AIR JUST ABOVE THE MOISTURE LAYER.

ANY RESIDUAL WNW WINDS WILL BECOME N BY LATE EVENING BEHIND THE
FRONT. A FEW GUSTS TO 18KT WILL BE POSSIBLE FOR AN HOUR OR TWO
PAST FROPA, THEN LIGHT WINDS SHOULD DEVELOP THE REST OF THE NIGHT
AND INTO TUESDAY.


&&

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

$$

UPDATE...SHIMON
SHORT TERM...HJS
LONG TERM...MILLER
AVIATION...SHIMON








000
FXUS63 KILX 160015 CCA
AFDILX

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE LINCOLN IL
715 PM CDT MON SEP 15 2014

.SHORT TERM...(TONIGHT)
ISSUED AT 321 PM CDT MON SEP 15 2014

STORM SYSTEM STILL IMPACTING CENTRAL ILLINOIS AHEAD OF AN
APPROACHING BOUNDARY.  SOME LOW CLOUDS AND DEVELOPING FOG IN THE
WAKE OF THE SHOWERS HINT TO THE MAIN ISSUES GOING INTO THE OVERNIGHT
HOURS TONIGHT.  SHOWERS AND THUNDERSTORMS SHOULD BEGIN TO WRAP UP
THIS EVENING BUT WET, MISTY, AND LOW CLOUDS SHOULD CONTINUE FOR A
LITTLE WHILE AT LEAST.  SATELLITE IMAGERY SHOWING THE LOW CLOUDS
HANGING AROUND A BIT AFTER THE WIND SHIFT/BOUNDARY MOVES THROUGH
WITH THE NW/N WINDS.  COOLER TONIGHT...BUT COOLEST IN THE NW WHERE
MOST LIKELY TO SEE SOME CLEARING.  TEMPS MAY BOTTOM OUT LOCALLY IF
THE CIGS CLEAR IN THE OVERNIGHT.  EITHER WAY, ENHANCED LLVL MOISTURE
WILL BRING WITH IT THE CHANCE FOR FOG DEVELOPMENT.  FOR NOW,
QUESTION IS BETWEEN DENSE FOG AND VERY LOW STRATUS.  STRATUS ALREADY
DEVELOPING AND SEE NO REASON TO BREAK THAT TREND, SO ONLY PUTTING IN
PATCHY FOG MENTION IN THE OVERNIGHT HOURS.

&&

.LONG TERM...(TUESDAY THROUGH MONDAY)
ISSUED AT 321 PM CDT MON SEP 15 2014

THE MEDIUM AND LONG RANGE MODELS ARE IN GENERALLY GOOD AGREEMENT
THAT A PROGRESSIVE UPPER LEVEL FLOW PATTERN WILL DOMINATE THROUGH
THE NEXT SEVEN DAYS.

SURFACE HIGH PRESSURE FROM THE NORTHERN PLAINS WILL WORK ITS WAY
TOWARD THE MIDWEST TUESDAY, RESULTING IN A CLEARING SKY AND A
CONTINUATION OF COOLER THAN NORMAL TEMPERATURES. A WEAK SHORTWAVE
TROUGH IN THE UPPER LEVEL NORTHWEST FLOW WILL APPROACH THE
MID-MISSISSIPPI RIVER VALLEY WEDNESDAY. HOWEVER, AN ABUNDANCE OF DRY
AIR IN THE LOWER LEVELS SHOULD KEEP CENTRAL AND EASTERN IL
RAIN-FREE. WOULD NOT BE SURPRISED TO SEE A SPRINKLE OR TWO IN AREAS
SOUTHWEST OF A RUSHVILLE-SPRINGFIELD LINE. WILL HOLD OFF ON THE
MENTION OF THAT FOR NOW AS THE FAVORABLE MOISTURE AND LIFT APPEARS
TO STAY ALONG AND WEST OF THE MS RIVER.

ANTICYCLONIC LOW LEVEL FLOW WILL CONTINUE TO DOMINATE THROUGH
THURSDAY AND FRIDAY KEEPING RAIN OUT OF THE FORECAST. A RETURN,
SOUTHERLY FLOW FRIDAY WILL FINALLY ALLOW TEMPERATURES TO CLIMB
TOWARD SEASONAL LEVELS IN THE 75-80 RANGE ACROSS MOST OF CENTRAL AND
SOUTHEAST IL.

WILL KEEP THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS IN THE
FORECAST WEST OF I-57 SATURDAY, AND ACROSS ALL OF CENTRAL AND
EASTERN IL SATURDAY NIGHT. THE EUROPEAN AND GFS MODELS ARE ACTUALLY
IN QUITE GOOD AGREEMENT THAT AN UPPER LEVEL TROUGH WILL ADVANCE FROM
THE ROCKIES FRIDAY TO THE MIDWEST LATER SATURDAY. THE SOUTHERLY LOW
LEVEL FLOW WILL ADVECT PLENTY OF MOISTURE AHEAD OF THE SURFACE COLD
FRONT, RESULTING IN SHOWERS AND THUNDERSTORMS. HOWEVER, THERE IS THE
POTENTIAL FOR HEAVY RAIN FROM THIS SYSTEM, PARTICULARLY ACCORDING TO
THE GFS SOLUTION. THE GFS DEPICTS THE REMNANTS OF HURRICANE ODILE,
CURRENTLY IN THE SOUTHERN CALIFORNIA BAJA REGION, EJECTING TOWARD
THE CENTRAL U.S. WITH DEEP TROPICAL MOISTURE. THIS WOULD EASILY
RESULT IN 1-3" OF RAIN ACROSS MUCH OF THE FORECAST AREA SATURDAY
INTO EARLY SUNDAY. HOWEVER, THE EUROPEAN AND CANADIAN MODELS ARE NOT
BUYING INTO THIS SOLUTION AT THE MOMENT. AS A RESULT, WILL WATCH
THIS POTENTIAL FOR THE NEXT SEVERAL FORECAST RUNS BEFORE INTRODUCING
A MENTION OF HEAVY RAIN.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 700 PM CDT MON SEP 15 2014

SHOWERS AND/OR DRIZZLE WILL LINGER FOR ANOTHER HOUR OR TWO AT THE
TERMINAL SITES EXCEPT PIA, WHICH IS SEEING CEILING HEIGHTS RISE TO
VFR PERIODICALLY DUE TO DRY AIR MIXING DOWN ALREADY. SATELLITE AND
OBSERVATIONS ARE INDICATING MVFR WILL RETURN TO PIA FOR SEVERAL
MORE HOURS BEFORE SOME CLEARING ARRIVES. CMI IS THE ONLY LIFR
SITE, WITH IFR AT SPI/BMI/DEC DUE TO LOW CIGS AND VIS. FORECAST
SOUNDINGS AND HRRR OUTPUT STILL SHOW PROGRESSIVELY IMPROVING
CONDITIONS BY LATE EVENING, WITH HIGH PRESSURE BUILDING BEHIND THE
DEPARTING COLD FRONT. THEREFORE, HAVE KEPT THE CLEARING TRENDS IN
THE CLOUD COVER, WITH FOG FORMATION LIKELY IN ANY AREAS THAT CLEAR
OUT. WENT LIFR OR VLIFR FOG FROM 11Z-13Z FOR THE NORTHERN
TERMINALS OF PIA/BMI/CMI, AND IFR AT SPI/DEC. THE TIMING MAY NEED
TO BE ADJUSTED, BUT FEELING MORE CONFIDENT THAT LOW LEVEL MOISTURE
WILL BECOME LOW STRATUS AND FOG ACROSS THE BOARD.

VFR CONDITIONS SHOULD DEVELOP QUICKLY TUESDAY MORNING WITH MIXING
OF VERY DRY AIR JUST ABOVE THE MOISTURE LAYER.

ANY RESIDUAL WNW WINDS WILL BECOME N BY LATE EVENING BEHIND THE
FRONT. A FEW GUSTS TO 18KT WILL BE POSSIBLE FOR AN HOUR OR TWO
PAST FROPA, THEN LIGHT WINDS SHOULD DEVELOP THE REST OF THE NIGHT
AND INTO TUESDAY.

&&

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

$$

SHORT TERM...HJS
LONG TERM...MILLER
AVIATION...SHIMON









000
FXUS63 KILX 160015 CCA
AFDILX

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE LINCOLN IL
715 PM CDT MON SEP 15 2014

.SHORT TERM...(TONIGHT)
ISSUED AT 321 PM CDT MON SEP 15 2014

STORM SYSTEM STILL IMPACTING CENTRAL ILLINOIS AHEAD OF AN
APPROACHING BOUNDARY.  SOME LOW CLOUDS AND DEVELOPING FOG IN THE
WAKE OF THE SHOWERS HINT TO THE MAIN ISSUES GOING INTO THE OVERNIGHT
HOURS TONIGHT.  SHOWERS AND THUNDERSTORMS SHOULD BEGIN TO WRAP UP
THIS EVENING BUT WET, MISTY, AND LOW CLOUDS SHOULD CONTINUE FOR A
LITTLE WHILE AT LEAST.  SATELLITE IMAGERY SHOWING THE LOW CLOUDS
HANGING AROUND A BIT AFTER THE WIND SHIFT/BOUNDARY MOVES THROUGH
WITH THE NW/N WINDS.  COOLER TONIGHT...BUT COOLEST IN THE NW WHERE
MOST LIKELY TO SEE SOME CLEARING.  TEMPS MAY BOTTOM OUT LOCALLY IF
THE CIGS CLEAR IN THE OVERNIGHT.  EITHER WAY, ENHANCED LLVL MOISTURE
WILL BRING WITH IT THE CHANCE FOR FOG DEVELOPMENT.  FOR NOW,
QUESTION IS BETWEEN DENSE FOG AND VERY LOW STRATUS.  STRATUS ALREADY
DEVELOPING AND SEE NO REASON TO BREAK THAT TREND, SO ONLY PUTTING IN
PATCHY FOG MENTION IN THE OVERNIGHT HOURS.

&&

.LONG TERM...(TUESDAY THROUGH MONDAY)
ISSUED AT 321 PM CDT MON SEP 15 2014

THE MEDIUM AND LONG RANGE MODELS ARE IN GENERALLY GOOD AGREEMENT
THAT A PROGRESSIVE UPPER LEVEL FLOW PATTERN WILL DOMINATE THROUGH
THE NEXT SEVEN DAYS.

SURFACE HIGH PRESSURE FROM THE NORTHERN PLAINS WILL WORK ITS WAY
TOWARD THE MIDWEST TUESDAY, RESULTING IN A CLEARING SKY AND A
CONTINUATION OF COOLER THAN NORMAL TEMPERATURES. A WEAK SHORTWAVE
TROUGH IN THE UPPER LEVEL NORTHWEST FLOW WILL APPROACH THE
MID-MISSISSIPPI RIVER VALLEY WEDNESDAY. HOWEVER, AN ABUNDANCE OF DRY
AIR IN THE LOWER LEVELS SHOULD KEEP CENTRAL AND EASTERN IL
RAIN-FREE. WOULD NOT BE SURPRISED TO SEE A SPRINKLE OR TWO IN AREAS
SOUTHWEST OF A RUSHVILLE-SPRINGFIELD LINE. WILL HOLD OFF ON THE
MENTION OF THAT FOR NOW AS THE FAVORABLE MOISTURE AND LIFT APPEARS
TO STAY ALONG AND WEST OF THE MS RIVER.

ANTICYCLONIC LOW LEVEL FLOW WILL CONTINUE TO DOMINATE THROUGH
THURSDAY AND FRIDAY KEEPING RAIN OUT OF THE FORECAST. A RETURN,
SOUTHERLY FLOW FRIDAY WILL FINALLY ALLOW TEMPERATURES TO CLIMB
TOWARD SEASONAL LEVELS IN THE 75-80 RANGE ACROSS MOST OF CENTRAL AND
SOUTHEAST IL.

WILL KEEP THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS IN THE
FORECAST WEST OF I-57 SATURDAY, AND ACROSS ALL OF CENTRAL AND
EASTERN IL SATURDAY NIGHT. THE EUROPEAN AND GFS MODELS ARE ACTUALLY
IN QUITE GOOD AGREEMENT THAT AN UPPER LEVEL TROUGH WILL ADVANCE FROM
THE ROCKIES FRIDAY TO THE MIDWEST LATER SATURDAY. THE SOUTHERLY LOW
LEVEL FLOW WILL ADVECT PLENTY OF MOISTURE AHEAD OF THE SURFACE COLD
FRONT, RESULTING IN SHOWERS AND THUNDERSTORMS. HOWEVER, THERE IS THE
POTENTIAL FOR HEAVY RAIN FROM THIS SYSTEM, PARTICULARLY ACCORDING TO
THE GFS SOLUTION. THE GFS DEPICTS THE REMNANTS OF HURRICANE ODILE,
CURRENTLY IN THE SOUTHERN CALIFORNIA BAJA REGION, EJECTING TOWARD
THE CENTRAL U.S. WITH DEEP TROPICAL MOISTURE. THIS WOULD EASILY
RESULT IN 1-3" OF RAIN ACROSS MUCH OF THE FORECAST AREA SATURDAY
INTO EARLY SUNDAY. HOWEVER, THE EUROPEAN AND CANADIAN MODELS ARE NOT
BUYING INTO THIS SOLUTION AT THE MOMENT. AS A RESULT, WILL WATCH
THIS POTENTIAL FOR THE NEXT SEVERAL FORECAST RUNS BEFORE INTRODUCING
A MENTION OF HEAVY RAIN.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 700 PM CDT MON SEP 15 2014

SHOWERS AND/OR DRIZZLE WILL LINGER FOR ANOTHER HOUR OR TWO AT THE
TERMINAL SITES EXCEPT PIA, WHICH IS SEEING CEILING HEIGHTS RISE TO
VFR PERIODICALLY DUE TO DRY AIR MIXING DOWN ALREADY. SATELLITE AND
OBSERVATIONS ARE INDICATING MVFR WILL RETURN TO PIA FOR SEVERAL
MORE HOURS BEFORE SOME CLEARING ARRIVES. CMI IS THE ONLY LIFR
SITE, WITH IFR AT SPI/BMI/DEC DUE TO LOW CIGS AND VIS. FORECAST
SOUNDINGS AND HRRR OUTPUT STILL SHOW PROGRESSIVELY IMPROVING
CONDITIONS BY LATE EVENING, WITH HIGH PRESSURE BUILDING BEHIND THE
DEPARTING COLD FRONT. THEREFORE, HAVE KEPT THE CLEARING TRENDS IN
THE CLOUD COVER, WITH FOG FORMATION LIKELY IN ANY AREAS THAT CLEAR
OUT. WENT LIFR OR VLIFR FOG FROM 11Z-13Z FOR THE NORTHERN
TERMINALS OF PIA/BMI/CMI, AND IFR AT SPI/DEC. THE TIMING MAY NEED
TO BE ADJUSTED, BUT FEELING MORE CONFIDENT THAT LOW LEVEL MOISTURE
WILL BECOME LOW STRATUS AND FOG ACROSS THE BOARD.

VFR CONDITIONS SHOULD DEVELOP QUICKLY TUESDAY MORNING WITH MIXING
OF VERY DRY AIR JUST ABOVE THE MOISTURE LAYER.

ANY RESIDUAL WNW WINDS WILL BECOME N BY LATE EVENING BEHIND THE
FRONT. A FEW GUSTS TO 18KT WILL BE POSSIBLE FOR AN HOUR OR TWO
PAST FROPA, THEN LIGHT WINDS SHOULD DEVELOP THE REST OF THE NIGHT
AND INTO TUESDAY.

&&

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

$$

SHORT TERM...HJS
LONG TERM...MILLER
AVIATION...SHIMON








000
FXUS63 KILX 160005
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
705 PM CDT Mon Sep 15 2014

.SHORT TERM...(Tonight)
ISSUED AT 321 PM CDT MON SEP 15 2014

Storm system still impacting Central Illinois ahead of an
approaching boundary.  Some low clouds and developing fog in the
wake of the showers hint to the main issues going into the overnight
hours tonight.  Showers and thunderstorms should begin to wrap up
this evening but wet, misty, and low clouds should continue for a
little while at least.  Satellite imagery showing the low clouds
hanging around a bit after the wind shift/boundary moves through
with the NW/N winds.  Cooler tonight...but coolest in the NW where
most likely to see some clearing.  Temps may bottom out locally if
the cigs clear in the overnight.  Either way, enhanced llvl moisture
will bring with it the chance for fog development.  For now,
question is between dense fog and very low stratus.  Stratus already
developing and see no reason to break that trend, so only putting in
patchy fog mention in the overnight hours.

&&

.LONG TERM...(Tuesday through Monday)
ISSUED AT 321 PM CDT MON SEP 15 2014

The medium and long range models are in generally good agreement
that a progressive upper level flow pattern will dominate through
the next seven days.

Surface high pressure from the northern Plains will work its way
toward the Midwest Tuesday, resulting in a clearing sky and a
continuation of cooler than normal temperatures. A weak shortwave
trough in the upper level northwest flow will approach the
mid-Mississippi River valley Wednesday. However, an abundance of dry
air in the lower levels should keep central and eastern IL
rain-free. Would not be surprised to see a sprinkle or two in areas
southwest of a Rushville-Springfield line. Will hold off on the
mention of that for now as the favorable moisture and lift appears
to stay along and west of the MS River.

Anticyclonic low level flow will continue to dominate through
Thursday and Friday keeping rain out of the forecast. A return,
southerly flow Friday will finally allow temperatures to climb
toward seasonal levels in the 75-80 range across most of central and
southeast IL.

Will keep the potential for showers and thunderstorms in the
forecast west of I-57 Saturday, and across all of central and
eastern IL Saturday night. The European and GFS models are actually
in quite good agreement that an upper level trough will advance from
the Rockies Friday to the Midwest later Saturday. The southerly low
level flow will advect plenty of moisture ahead of the surface cold
front, resulting in showers and thunderstorms. However, there is the
potential for heavy rain from this system, particularly according to
the GFS solution. The GFS depicts the remnants of Hurricane Odile,
currently in the southern California Baja region, ejecting toward
the central U.S. with deep tropical moisture. This would easily
result in 1-3" of rain across much of the forecast area Saturday
into early Sunday. However, the European and Canadian models are not
buying into this solution at the moment. As a result, will watch
this potential for the next several forecast runs before introducing
a mention of heavy rain.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 700 PM CDT MON SEP 15 2014

Showers and/or drizzle will linger for another hour or two at the
terminal sites except PIA, which is seeing ceiling heights rise to
VFR periodically due to dry air mixing down already. Satellite and
observations are indicating MVFR will return to PIA for several
more hours before some clearing arrives. CMI is the only LIFR
site, with IFR at SPI/BMI/DEC due to low cigs and vis. Forecast
soundings and HRRR output still show progressively improving
conditions by late evening, with high pressure building behind the
departing cold front. Therefore, have kept the clearing trends in
the cloud cover, with fog formation likely in any areas that clear
out. Went LIFR or VLIFR fog FROM 11Z-13Z for the northern
terminals of PIA/BMI/CMI, and IFR at SPI/DEC. The timing may need
to be adjusted, but feeling more confident that low level moisture
will become low stratus and fog across the board.

VFR conditions should develop quickly Tuesday morning with mixing
of very dry air just above the moisture layer.

Any residual WNW winds will become N by late evening behind the
front. A few gusts to 18kt will be possible for an hour or two
past FROPA, then light winds should develop the rest of the night
and into Tuesday.

Mostly IFR at terminals this afternoon.
Conditions improving to MVFR later this evening and through the
night. Scattering out the low clouds per time heights in both the
GFS and the NAM as well as HRRR. At time of issuance, PIA cigs at
500 ft were isolated. However, in the wake of the showers, GBG and
C75 have both dropped, which is in line with a progression of the
IFR line behind the showers. Concern that the IFR cigs will remain
after 20z- 22z at the end of the tempos up to potentially 00z and
will likely be amending. Models clearing out the skies quicker
will assist in the potential for fog in the morning hours. Started
the trend, but conservative for now. VWP lighting up a LLWS issue
with some SW winds just off the deck at 35kts. Somewhat isolated,
but will amend accordingly.

&&

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

$$

SHORT TERM...HJS
LONG TERM...MILLER
AVIATION...SHIMON






000
FXUS63 KILX 160005
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
705 PM CDT Mon Sep 15 2014

.SHORT TERM...(Tonight)
ISSUED AT 321 PM CDT MON SEP 15 2014

Storm system still impacting Central Illinois ahead of an
approaching boundary.  Some low clouds and developing fog in the
wake of the showers hint to the main issues going into the overnight
hours tonight.  Showers and thunderstorms should begin to wrap up
this evening but wet, misty, and low clouds should continue for a
little while at least.  Satellite imagery showing the low clouds
hanging around a bit after the wind shift/boundary moves through
with the NW/N winds.  Cooler tonight...but coolest in the NW where
most likely to see some clearing.  Temps may bottom out locally if
the cigs clear in the overnight.  Either way, enhanced llvl moisture
will bring with it the chance for fog development.  For now,
question is between dense fog and very low stratus.  Stratus already
developing and see no reason to break that trend, so only putting in
patchy fog mention in the overnight hours.

&&

.LONG TERM...(Tuesday through Monday)
ISSUED AT 321 PM CDT MON SEP 15 2014

The medium and long range models are in generally good agreement
that a progressive upper level flow pattern will dominate through
the next seven days.

Surface high pressure from the northern Plains will work its way
toward the Midwest Tuesday, resulting in a clearing sky and a
continuation of cooler than normal temperatures. A weak shortwave
trough in the upper level northwest flow will approach the
mid-Mississippi River valley Wednesday. However, an abundance of dry
air in the lower levels should keep central and eastern IL
rain-free. Would not be surprised to see a sprinkle or two in areas
southwest of a Rushville-Springfield line. Will hold off on the
mention of that for now as the favorable moisture and lift appears
to stay along and west of the MS River.

Anticyclonic low level flow will continue to dominate through
Thursday and Friday keeping rain out of the forecast. A return,
southerly flow Friday will finally allow temperatures to climb
toward seasonal levels in the 75-80 range across most of central and
southeast IL.

Will keep the potential for showers and thunderstorms in the
forecast west of I-57 Saturday, and across all of central and
eastern IL Saturday night. The European and GFS models are actually
in quite good agreement that an upper level trough will advance from
the Rockies Friday to the Midwest later Saturday. The southerly low
level flow will advect plenty of moisture ahead of the surface cold
front, resulting in showers and thunderstorms. However, there is the
potential for heavy rain from this system, particularly according to
the GFS solution. The GFS depicts the remnants of Hurricane Odile,
currently in the southern California Baja region, ejecting toward
the central U.S. with deep tropical moisture. This would easily
result in 1-3" of rain across much of the forecast area Saturday
into early Sunday. However, the European and Canadian models are not
buying into this solution at the moment. As a result, will watch
this potential for the next several forecast runs before introducing
a mention of heavy rain.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 700 PM CDT MON SEP 15 2014

Showers and/or drizzle will linger for another hour or two at the
terminal sites except PIA, which is seeing ceiling heights rise to
VFR periodically due to dry air mixing down already. Satellite and
observations are indicating MVFR will return to PIA for several
more hours before some clearing arrives. CMI is the only LIFR
site, with IFR at SPI/BMI/DEC due to low cigs and vis. Forecast
soundings and HRRR output still show progressively improving
conditions by late evening, with high pressure building behind the
departing cold front. Therefore, have kept the clearing trends in
the cloud cover, with fog formation likely in any areas that clear
out. Went LIFR or VLIFR fog FROM 11Z-13Z for the northern
terminals of PIA/BMI/CMI, and IFR at SPI/DEC. The timing may need
to be adjusted, but feeling more confident that low level moisture
will become low stratus and fog across the board.

VFR conditions should develop quickly Tuesday morning with mixing
of very dry air just above the moisture layer.

Any residual WNW winds will become N by late evening behind the
front. A few gusts to 18kt will be possible for an hour or two
past FROPA, then light winds should develop the rest of the night
and into Tuesday.

Mostly IFR at terminals this afternoon.
Conditions improving to MVFR later this evening and through the
night. Scattering out the low clouds per time heights in both the
GFS and the NAM as well as HRRR. At time of issuance, PIA cigs at
500 ft were isolated. However, in the wake of the showers, GBG and
C75 have both dropped, which is in line with a progression of the
IFR line behind the showers. Concern that the IFR cigs will remain
after 20z- 22z at the end of the tempos up to potentially 00z and
will likely be amending. Models clearing out the skies quicker
will assist in the potential for fog in the morning hours. Started
the trend, but conservative for now. VWP lighting up a LLWS issue
with some SW winds just off the deck at 35kts. Somewhat isolated,
but will amend accordingly.

&&

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

$$

SHORT TERM...HJS
LONG TERM...MILLER
AVIATION...SHIMON







000
FXUS63 KLOT 152341
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
641 PM CDT MON SEP 15 2014

.DISCUSSION...
221 PM CDT

TONIGHT...
FRONTAL BOUNDARY THIS AFTERNOON CONTINUES TO SLIDE SOUTHEAST ACROSS
THE FORECAST AREA. VISIBLE IMAGERY ALONG AND JUST AHEAD OF THE
BOUNDARY INDICATED SOME VERTICAL GROWTH TO THE CLOUDS...SUGGESTIVE
OF SOME INSTABILITY. THERE HAS BEEN SOME SPOTTY CONVECTION ACROSS
NORTHEAST MO STRETCHING EAST THROUGH IL/CENTRAL IN BUT SOUTH OF THE
CWFA. DESPITE CONSIDERABLE SOLAR SHIELDING HAS BEEN ABLE TO KEEP
TEMPS IN THE 50S...WITH A FEW LOCATIONS BEING ABLE TO NUDGE TO ARND
60. WINDS WILL SHIFT NORTHWEST/NORTH BEHIND THE BOUNDARY WITH MUCH
DRIER/COOLER AIR STEADILY FILTERING INTO THE REGION OVERNIGHT.
PRECIP WILL COME TO AN END LATER THIS AFTN/EARLY EVE...WITH JUST A
FEW LINGERING SHOWERS ALONG AND EAST OF GIBSON CITY TO FOWLER. TEMPS
OVERNIGHT WILL COOL INTO THE LOW/MID 40S...WITH A FEW OF THE
TRADITIONALLY COOL SPOTS POSSIBLY DIPPING INTO THE UPR 30S BEFORE
DAYBREAK TUE. MEANWHILE CLOSER TO DOWNTOWN CHICAGO...THE URBAN HEAT
ISLAND SHUD AID IN KEEPING TEMPS IN THE UPR 40S TO ARND 50. THE ONLY
WILDCARD FOR OVERNIGHT LOWS WILL BE SKY COVER/WINDS...WHICH WITH
HIGH PRESSURE BUILDING IN SHUD ERODE/DIMINISH.

THERE IS ALSO SOME CONCERN THAT WITH THE LACK MIXING THIS AFTN AND
EXPECTED TEMPS BEING COOLER THAN AFTN DEW PTS...COUPLED WITH LIGHT
WINDS...COULD POINT TOWARDS PATCHY FOG DEVELOPING AWAY FROM THE
METRO AREA.

TUESDAY THROUGH THURSDAY...
RATHER BENIGN PATTERN FOR A GOOD PORTION OF THE WEEK. BROAD
ANTI-CYCLONIC FLOW WILL BUILD INTO THE REGION TUESDAY...WITH THE
MID-LVL TROUGH PIVOTING EAST. THE LONGWAVE PATTERN WILL LIKELY KEEP
THE REGION IN A CONTINUED NORTHWEST FLOW AS MID-LVL RIDGING RETURNS
TO THE WESTERN CONUS. GUIDANCE SUGGESTS THE SFC RIDGE THAT ARRIVES
TUE WILL SHIFT EAST...HOWEVER ANOTHER DOME OF HIGH PRESSURE FROM
CANADA IS THEN POISED TO SLIDE SOUTH AND CONTINUE THE DRY/COOL
WEATHER WED/THUR. TEMPS WILL GENERALLY REMAIN IN THE MID/UPR
60S...BUT POSSIBLY REACH 70 DEG IN SEVERAL AREAS FOR THUR. ABUNDANT
SUNSHINE IS EXPECTED EACH OF THE NEXT SEVERAL DAYS AS WELL.
OVERNIGHT LOWS WILL ALSO DIP INTO THE 40S TUE NGT/WED NGT...THEN
WITH THE SFC RIDGE BEGINNING TO PUSH EAST THUR NGT TEMPS COULD HOLD
ARND 50.

CONFIDENCE...HIGH.

FRIDAY THROUGH SUNDAY...
WITH THE SFC RIDGE POISED TO PUSH EAST OF THE REGION FRI...FLOW WILL
BE TURNING SOUTHERLY AND THE MID-LVL WAVE STARTING TO FLATTEN.
ENSEMBLES CONTINUE TO SHOW CONSIDERABLE SPREAD ON TIMING OF
PRECIP/MOISTURE RETURNING...WITH MOST MEMBERS POINTING TOWARDS FRI
NGT. THE ATMOSPHERE WILL MODERATE BY FRI/SAT WITH TEMPS IN THE
MID/UPR 70S...OR MORE SEASONAL. SAT APPEARS TO BE THE MOST FAVORABLE
PERIOD TO SEE SPOTTY SHOWERS/THUNDERSTORMS AS A MID-LVL TROUGH
DEVELOPS OVER THE CENTRAL PLAINS AND NEARS THE REGION SAT AFTN/EVE.
THEN FOR THE SECOND HALF OF THE WEEKEND SFC RIDGING IS PROGGED TO
RETURN TO THE REGION.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* N-NNE WINDS SETTLING BELOW 10 KT NEXT 1-2 HRS.

* MVFR CIGS SCATTERING/CLEARING TOWARD MID EVENING.

* LIGHT WEST TO NORTHWEST WINDS TUESDAY. LAKE BREEZE EXPECTED TO
  STAY TO THE EAST.

MDB

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

FRONTAL BOUNDARY IS NOW APPROACHING MDW AND WILL PASS GYY EARLY
THIS EVENING TURNING WINDS NORTHERLY WITH AN INITIAL INCREASE IN
SPEED TO 10-15 KT. SPEEDS WILL SETTLE UNDER 10 KT THROUGH EARLY
EVENING BEHIND THE FRONT THOUGH GYY MAY KEEP SPEEDS ABOVE 10 KT
INTO MID EVENING. SATELLITE SHOWS THE BACK EDGE OF THE MAIN CLOUD
SHIELD MOVING QUICKLY SOUTHEAST WITH THE DIURNAL STRATO CU TO THE
NORTHWEST QUICKLY DISSIPATING. EXPECT SKIES TO CLEAR BY MID
EVENING ACROSS THE IL TERMINALS WITH LAKE EFFECT PROCESSES
POTENTIALLY KEEPING MVFR CLOUDS AT GYY INTO THE OVERNIGHT. SOME
RESIDUAL LOW LEVEL MOISTURE MAY ALLOW FOR SOME PATCHY OR SHALLOW
FOG OVERNIGHT AT RFD/DPA AS WINDS DIMINISH. NORTHWEST WINDS WILL
BECOME WESTERLY UNDER 10 KT AT THE IL TERMINALS TUESDAY. A LAKE
BREEZE WILL LIKELY DEVELOP BY MIDDAY BRINGING NE WINDS TO GYY BUT
THE INLAND PUSH LOOKS TO BE SLOW GIVEN THE MINIMAL LAKE-LAND TEMP
DIFFERENCE SO WILL KEEP IT EAST OF ORD/MDW FOR NOW. SOME SCATTERED
STRATO CU IS EXPECTED TO DEVELOP LATE MORNING THEN LIFT/DISSIPATE
THROUGH THE AFTERNOON.

MDB

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

* MEDIUM-HIGH CONFIDENCE IN TIMING OF WINDS DROPPING BELOW 10 KT.

* HIGH CONFIDENCE IN MVFR CIGS SCATTERING/CLEARING...MEDIUM-HIGH
  CONFIDENCE IN TIMING.

* HIGH CONFIDENCE IN WEST TO NORTHWEST WINDS TUESDAY. MEDIUM-HIGH
  CONFIDENCE ANY LAKE BREEZE WILL REMAIN EAST.

MDB

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

WEDNESDAY...VFR. LIGHT WEST WINDS. LAKE BREEZE POSSIBLE.

THURSDAY...VFR. EAST WINDS.

FRIDAY...VFR. BREEZY SOUTH WINDS.

SATURDAY...CHANCE TSRA. MVFR POSSIBLE. BREEZY SOUTHWEST WINDS.

SUNDAY...SLIGHT CHANCE TSRA. VFR. WEST WINDS.

MDB

&&

.MARINE...
246 PM CDT

WEAK LOW PRESSURE WILL PUSH EAST THROUGH THE OHIO VALLEY AND
DISSIPATE THIS EVENING AS HIGH PRESSURE MOVES INTO THE MID
MISSOURI VALLEY TONIGHT. AHEAD OF THE HIGH A WEAK COLD FRONT WILL
SPREAD DOWN THE REMAINDER OF THE LAKE THIS EVENING AND BRIEFLY
INCREASE NORTH WINDS TO NEAR 20 KT THE HIGH WILL WEAKEN AND MOVE
OVER LAKE MICHIGAN ON TUESDAY. LOW PRESSURE OVER HUDSON BAY WILL
SPREAD INTO QUEBEC ON WEDNESDAY AS HIGH PRESSURE PUSHES SOUTH OUT
OF NORTHERN MANITOBA. AHEAD OF THE HIGH THE SOUTHWEST GRADIENT
INCREASES WITH WINDS 15 TO 25 KT FOR THE NORTH HALF OF THE LAKE. THE
HIGH REACHES LAKE SUPERIOR THURSDAY EVENING AND WILL PUSH A COLD
FRONT DOWN THE LAKE THURSDAY NIGHT. THIS HIGH WILL THEN MOVE TO
THE EASTERN LAKES BY LATE THURSDAY INTO FRIDAY AS SEVERAL LOWS
ORGANIZE IN THE CENTRAL PLAINS AND CANADIAN PRAIRIES.

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 152341
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
641 PM CDT MON SEP 15 2014

.DISCUSSION...
221 PM CDT

TONIGHT...
FRONTAL BOUNDARY THIS AFTERNOON CONTINUES TO SLIDE SOUTHEAST ACROSS
THE FORECAST AREA. VISIBLE IMAGERY ALONG AND JUST AHEAD OF THE
BOUNDARY INDICATED SOME VERTICAL GROWTH TO THE CLOUDS...SUGGESTIVE
OF SOME INSTABILITY. THERE HAS BEEN SOME SPOTTY CONVECTION ACROSS
NORTHEAST MO STRETCHING EAST THROUGH IL/CENTRAL IN BUT SOUTH OF THE
CWFA. DESPITE CONSIDERABLE SOLAR SHIELDING HAS BEEN ABLE TO KEEP
TEMPS IN THE 50S...WITH A FEW LOCATIONS BEING ABLE TO NUDGE TO ARND
60. WINDS WILL SHIFT NORTHWEST/NORTH BEHIND THE BOUNDARY WITH MUCH
DRIER/COOLER AIR STEADILY FILTERING INTO THE REGION OVERNIGHT.
PRECIP WILL COME TO AN END LATER THIS AFTN/EARLY EVE...WITH JUST A
FEW LINGERING SHOWERS ALONG AND EAST OF GIBSON CITY TO FOWLER. TEMPS
OVERNIGHT WILL COOL INTO THE LOW/MID 40S...WITH A FEW OF THE
TRADITIONALLY COOL SPOTS POSSIBLY DIPPING INTO THE UPR 30S BEFORE
DAYBREAK TUE. MEANWHILE CLOSER TO DOWNTOWN CHICAGO...THE URBAN HEAT
ISLAND SHUD AID IN KEEPING TEMPS IN THE UPR 40S TO ARND 50. THE ONLY
WILDCARD FOR OVERNIGHT LOWS WILL BE SKY COVER/WINDS...WHICH WITH
HIGH PRESSURE BUILDING IN SHUD ERODE/DIMINISH.

THERE IS ALSO SOME CONCERN THAT WITH THE LACK MIXING THIS AFTN AND
EXPECTED TEMPS BEING COOLER THAN AFTN DEW PTS...COUPLED WITH LIGHT
WINDS...COULD POINT TOWARDS PATCHY FOG DEVELOPING AWAY FROM THE
METRO AREA.

TUESDAY THROUGH THURSDAY...
RATHER BENIGN PATTERN FOR A GOOD PORTION OF THE WEEK. BROAD
ANTI-CYCLONIC FLOW WILL BUILD INTO THE REGION TUESDAY...WITH THE
MID-LVL TROUGH PIVOTING EAST. THE LONGWAVE PATTERN WILL LIKELY KEEP
THE REGION IN A CONTINUED NORTHWEST FLOW AS MID-LVL RIDGING RETURNS
TO THE WESTERN CONUS. GUIDANCE SUGGESTS THE SFC RIDGE THAT ARRIVES
TUE WILL SHIFT EAST...HOWEVER ANOTHER DOME OF HIGH PRESSURE FROM
CANADA IS THEN POISED TO SLIDE SOUTH AND CONTINUE THE DRY/COOL
WEATHER WED/THUR. TEMPS WILL GENERALLY REMAIN IN THE MID/UPR
60S...BUT POSSIBLY REACH 70 DEG IN SEVERAL AREAS FOR THUR. ABUNDANT
SUNSHINE IS EXPECTED EACH OF THE NEXT SEVERAL DAYS AS WELL.
OVERNIGHT LOWS WILL ALSO DIP INTO THE 40S TUE NGT/WED NGT...THEN
WITH THE SFC RIDGE BEGINNING TO PUSH EAST THUR NGT TEMPS COULD HOLD
ARND 50.

CONFIDENCE...HIGH.

FRIDAY THROUGH SUNDAY...
WITH THE SFC RIDGE POISED TO PUSH EAST OF THE REGION FRI...FLOW WILL
BE TURNING SOUTHERLY AND THE MID-LVL WAVE STARTING TO FLATTEN.
ENSEMBLES CONTINUE TO SHOW CONSIDERABLE SPREAD ON TIMING OF
PRECIP/MOISTURE RETURNING...WITH MOST MEMBERS POINTING TOWARDS FRI
NGT. THE ATMOSPHERE WILL MODERATE BY FRI/SAT WITH TEMPS IN THE
MID/UPR 70S...OR MORE SEASONAL. SAT APPEARS TO BE THE MOST FAVORABLE
PERIOD TO SEE SPOTTY SHOWERS/THUNDERSTORMS AS A MID-LVL TROUGH
DEVELOPS OVER THE CENTRAL PLAINS AND NEARS THE REGION SAT AFTN/EVE.
THEN FOR THE SECOND HALF OF THE WEEKEND SFC RIDGING IS PROGGED TO
RETURN TO THE REGION.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* N-NNE WINDS SETTLING BELOW 10 KT NEXT 1-2 HRS.

* MVFR CIGS SCATTERING/CLEARING TOWARD MID EVENING.

* LIGHT WEST TO NORTHWEST WINDS TUESDAY. LAKE BREEZE EXPECTED TO
  STAY TO THE EAST.

MDB

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

FRONTAL BOUNDARY IS NOW APPROACHING MDW AND WILL PASS GYY EARLY
THIS EVENING TURNING WINDS NORTHERLY WITH AN INITIAL INCREASE IN
SPEED TO 10-15 KT. SPEEDS WILL SETTLE UNDER 10 KT THROUGH EARLY
EVENING BEHIND THE FRONT THOUGH GYY MAY KEEP SPEEDS ABOVE 10 KT
INTO MID EVENING. SATELLITE SHOWS THE BACK EDGE OF THE MAIN CLOUD
SHIELD MOVING QUICKLY SOUTHEAST WITH THE DIURNAL STRATO CU TO THE
NORTHWEST QUICKLY DISSIPATING. EXPECT SKIES TO CLEAR BY MID
EVENING ACROSS THE IL TERMINALS WITH LAKE EFFECT PROCESSES
POTENTIALLY KEEPING MVFR CLOUDS AT GYY INTO THE OVERNIGHT. SOME
RESIDUAL LOW LEVEL MOISTURE MAY ALLOW FOR SOME PATCHY OR SHALLOW
FOG OVERNIGHT AT RFD/DPA AS WINDS DIMINISH. NORTHWEST WINDS WILL
BECOME WESTERLY UNDER 10 KT AT THE IL TERMINALS TUESDAY. A LAKE
BREEZE WILL LIKELY DEVELOP BY MIDDAY BRINGING NE WINDS TO GYY BUT
THE INLAND PUSH LOOKS TO BE SLOW GIVEN THE MINIMAL LAKE-LAND TEMP
DIFFERENCE SO WILL KEEP IT EAST OF ORD/MDW FOR NOW. SOME SCATTERED
STRATO CU IS EXPECTED TO DEVELOP LATE MORNING THEN LIFT/DISSIPATE
THROUGH THE AFTERNOON.

MDB

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

* MEDIUM-HIGH CONFIDENCE IN TIMING OF WINDS DROPPING BELOW 10 KT.

* HIGH CONFIDENCE IN MVFR CIGS SCATTERING/CLEARING...MEDIUM-HIGH
  CONFIDENCE IN TIMING.

* HIGH CONFIDENCE IN WEST TO NORTHWEST WINDS TUESDAY. MEDIUM-HIGH
  CONFIDENCE ANY LAKE BREEZE WILL REMAIN EAST.

MDB

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

WEDNESDAY...VFR. LIGHT WEST WINDS. LAKE BREEZE POSSIBLE.

THURSDAY...VFR. EAST WINDS.

FRIDAY...VFR. BREEZY SOUTH WINDS.

SATURDAY...CHANCE TSRA. MVFR POSSIBLE. BREEZY SOUTHWEST WINDS.

SUNDAY...SLIGHT CHANCE TSRA. VFR. WEST WINDS.

MDB

&&

.MARINE...
246 PM CDT

WEAK LOW PRESSURE WILL PUSH EAST THROUGH THE OHIO VALLEY AND
DISSIPATE THIS EVENING AS HIGH PRESSURE MOVES INTO THE MID
MISSOURI VALLEY TONIGHT. AHEAD OF THE HIGH A WEAK COLD FRONT WILL
SPREAD DOWN THE REMAINDER OF THE LAKE THIS EVENING AND BRIEFLY
INCREASE NORTH WINDS TO NEAR 20 KT THE HIGH WILL WEAKEN AND MOVE
OVER LAKE MICHIGAN ON TUESDAY. LOW PRESSURE OVER HUDSON BAY WILL
SPREAD INTO QUEBEC ON WEDNESDAY AS HIGH PRESSURE PUSHES SOUTH OUT
OF NORTHERN MANITOBA. AHEAD OF THE HIGH THE SOUTHWEST GRADIENT
INCREASES WITH WINDS 15 TO 25 KT FOR THE NORTH HALF OF THE LAKE. THE
HIGH REACHES LAKE SUPERIOR THURSDAY EVENING AND WILL PUSH A COLD
FRONT DOWN THE LAKE THURSDAY NIGHT. THIS HIGH WILL THEN MOVE TO
THE EASTERN LAKES BY LATE THURSDAY INTO FRIDAY AS SEVERAL LOWS
ORGANIZE IN THE CENTRAL PLAINS AND CANADIAN PRAIRIES.

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 152341
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
641 PM CDT MON SEP 15 2014

.DISCUSSION...
221 PM CDT

TONIGHT...
FRONTAL BOUNDARY THIS AFTERNOON CONTINUES TO SLIDE SOUTHEAST ACROSS
THE FORECAST AREA. VISIBLE IMAGERY ALONG AND JUST AHEAD OF THE
BOUNDARY INDICATED SOME VERTICAL GROWTH TO THE CLOUDS...SUGGESTIVE
OF SOME INSTABILITY. THERE HAS BEEN SOME SPOTTY CONVECTION ACROSS
NORTHEAST MO STRETCHING EAST THROUGH IL/CENTRAL IN BUT SOUTH OF THE
CWFA. DESPITE CONSIDERABLE SOLAR SHIELDING HAS BEEN ABLE TO KEEP
TEMPS IN THE 50S...WITH A FEW LOCATIONS BEING ABLE TO NUDGE TO ARND
60. WINDS WILL SHIFT NORTHWEST/NORTH BEHIND THE BOUNDARY WITH MUCH
DRIER/COOLER AIR STEADILY FILTERING INTO THE REGION OVERNIGHT.
PRECIP WILL COME TO AN END LATER THIS AFTN/EARLY EVE...WITH JUST A
FEW LINGERING SHOWERS ALONG AND EAST OF GIBSON CITY TO FOWLER. TEMPS
OVERNIGHT WILL COOL INTO THE LOW/MID 40S...WITH A FEW OF THE
TRADITIONALLY COOL SPOTS POSSIBLY DIPPING INTO THE UPR 30S BEFORE
DAYBREAK TUE. MEANWHILE CLOSER TO DOWNTOWN CHICAGO...THE URBAN HEAT
ISLAND SHUD AID IN KEEPING TEMPS IN THE UPR 40S TO ARND 50. THE ONLY
WILDCARD FOR OVERNIGHT LOWS WILL BE SKY COVER/WINDS...WHICH WITH
HIGH PRESSURE BUILDING IN SHUD ERODE/DIMINISH.

THERE IS ALSO SOME CONCERN THAT WITH THE LACK MIXING THIS AFTN AND
EXPECTED TEMPS BEING COOLER THAN AFTN DEW PTS...COUPLED WITH LIGHT
WINDS...COULD POINT TOWARDS PATCHY FOG DEVELOPING AWAY FROM THE
METRO AREA.

TUESDAY THROUGH THURSDAY...
RATHER BENIGN PATTERN FOR A GOOD PORTION OF THE WEEK. BROAD
ANTI-CYCLONIC FLOW WILL BUILD INTO THE REGION TUESDAY...WITH THE
MID-LVL TROUGH PIVOTING EAST. THE LONGWAVE PATTERN WILL LIKELY KEEP
THE REGION IN A CONTINUED NORTHWEST FLOW AS MID-LVL RIDGING RETURNS
TO THE WESTERN CONUS. GUIDANCE SUGGESTS THE SFC RIDGE THAT ARRIVES
TUE WILL SHIFT EAST...HOWEVER ANOTHER DOME OF HIGH PRESSURE FROM
CANADA IS THEN POISED TO SLIDE SOUTH AND CONTINUE THE DRY/COOL
WEATHER WED/THUR. TEMPS WILL GENERALLY REMAIN IN THE MID/UPR
60S...BUT POSSIBLY REACH 70 DEG IN SEVERAL AREAS FOR THUR. ABUNDANT
SUNSHINE IS EXPECTED EACH OF THE NEXT SEVERAL DAYS AS WELL.
OVERNIGHT LOWS WILL ALSO DIP INTO THE 40S TUE NGT/WED NGT...THEN
WITH THE SFC RIDGE BEGINNING TO PUSH EAST THUR NGT TEMPS COULD HOLD
ARND 50.

CONFIDENCE...HIGH.

FRIDAY THROUGH SUNDAY...
WITH THE SFC RIDGE POISED TO PUSH EAST OF THE REGION FRI...FLOW WILL
BE TURNING SOUTHERLY AND THE MID-LVL WAVE STARTING TO FLATTEN.
ENSEMBLES CONTINUE TO SHOW CONSIDERABLE SPREAD ON TIMING OF
PRECIP/MOISTURE RETURNING...WITH MOST MEMBERS POINTING TOWARDS FRI
NGT. THE ATMOSPHERE WILL MODERATE BY FRI/SAT WITH TEMPS IN THE
MID/UPR 70S...OR MORE SEASONAL. SAT APPEARS TO BE THE MOST FAVORABLE
PERIOD TO SEE SPOTTY SHOWERS/THUNDERSTORMS AS A MID-LVL TROUGH
DEVELOPS OVER THE CENTRAL PLAINS AND NEARS THE REGION SAT AFTN/EVE.
THEN FOR THE SECOND HALF OF THE WEEKEND SFC RIDGING IS PROGGED TO
RETURN TO THE REGION.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* N-NNE WINDS SETTLING BELOW 10 KT NEXT 1-2 HRS.

* MVFR CIGS SCATTERING/CLEARING TOWARD MID EVENING.

* LIGHT WEST TO NORTHWEST WINDS TUESDAY. LAKE BREEZE EXPECTED TO
  STAY TO THE EAST.

MDB

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

FRONTAL BOUNDARY IS NOW APPROACHING MDW AND WILL PASS GYY EARLY
THIS EVENING TURNING WINDS NORTHERLY WITH AN INITIAL INCREASE IN
SPEED TO 10-15 KT. SPEEDS WILL SETTLE UNDER 10 KT THROUGH EARLY
EVENING BEHIND THE FRONT THOUGH GYY MAY KEEP SPEEDS ABOVE 10 KT
INTO MID EVENING. SATELLITE SHOWS THE BACK EDGE OF THE MAIN CLOUD
SHIELD MOVING QUICKLY SOUTHEAST WITH THE DIURNAL STRATO CU TO THE
NORTHWEST QUICKLY DISSIPATING. EXPECT SKIES TO CLEAR BY MID
EVENING ACROSS THE IL TERMINALS WITH LAKE EFFECT PROCESSES
POTENTIALLY KEEPING MVFR CLOUDS AT GYY INTO THE OVERNIGHT. SOME
RESIDUAL LOW LEVEL MOISTURE MAY ALLOW FOR SOME PATCHY OR SHALLOW
FOG OVERNIGHT AT RFD/DPA AS WINDS DIMINISH. NORTHWEST WINDS WILL
BECOME WESTERLY UNDER 10 KT AT THE IL TERMINALS TUESDAY. A LAKE
BREEZE WILL LIKELY DEVELOP BY MIDDAY BRINGING NE WINDS TO GYY BUT
THE INLAND PUSH LOOKS TO BE SLOW GIVEN THE MINIMAL LAKE-LAND TEMP
DIFFERENCE SO WILL KEEP IT EAST OF ORD/MDW FOR NOW. SOME SCATTERED
STRATO CU IS EXPECTED TO DEVELOP LATE MORNING THEN LIFT/DISSIPATE
THROUGH THE AFTERNOON.

MDB

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

* MEDIUM-HIGH CONFIDENCE IN TIMING OF WINDS DROPPING BELOW 10 KT.

* HIGH CONFIDENCE IN MVFR CIGS SCATTERING/CLEARING...MEDIUM-HIGH
  CONFIDENCE IN TIMING.

* HIGH CONFIDENCE IN WEST TO NORTHWEST WINDS TUESDAY. MEDIUM-HIGH
  CONFIDENCE ANY LAKE BREEZE WILL REMAIN EAST.

MDB

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

WEDNESDAY...VFR. LIGHT WEST WINDS. LAKE BREEZE POSSIBLE.

THURSDAY...VFR. EAST WINDS.

FRIDAY...VFR. BREEZY SOUTH WINDS.

SATURDAY...CHANCE TSRA. MVFR POSSIBLE. BREEZY SOUTHWEST WINDS.

SUNDAY...SLIGHT CHANCE TSRA. VFR. WEST WINDS.

MDB

&&

.MARINE...
246 PM CDT

WEAK LOW PRESSURE WILL PUSH EAST THROUGH THE OHIO VALLEY AND
DISSIPATE THIS EVENING AS HIGH PRESSURE MOVES INTO THE MID
MISSOURI VALLEY TONIGHT. AHEAD OF THE HIGH A WEAK COLD FRONT WILL
SPREAD DOWN THE REMAINDER OF THE LAKE THIS EVENING AND BRIEFLY
INCREASE NORTH WINDS TO NEAR 20 KT THE HIGH WILL WEAKEN AND MOVE
OVER LAKE MICHIGAN ON TUESDAY. LOW PRESSURE OVER HUDSON BAY WILL
SPREAD INTO QUEBEC ON WEDNESDAY AS HIGH PRESSURE PUSHES SOUTH OUT
OF NORTHERN MANITOBA. AHEAD OF THE HIGH THE SOUTHWEST GRADIENT
INCREASES WITH WINDS 15 TO 25 KT FOR THE NORTH HALF OF THE LAKE. THE
HIGH REACHES LAKE SUPERIOR THURSDAY EVENING AND WILL PUSH A COLD
FRONT DOWN THE LAKE THURSDAY NIGHT. THIS HIGH WILL THEN MOVE TO
THE EASTERN LAKES BY LATE THURSDAY INTO FRIDAY AS SEVERAL LOWS
ORGANIZE IN THE CENTRAL PLAINS AND CANADIAN PRAIRIES.

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 152341
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
641 PM CDT MON SEP 15 2014

.DISCUSSION...
221 PM CDT

TONIGHT...
FRONTAL BOUNDARY THIS AFTERNOON CONTINUES TO SLIDE SOUTHEAST ACROSS
THE FORECAST AREA. VISIBLE IMAGERY ALONG AND JUST AHEAD OF THE
BOUNDARY INDICATED SOME VERTICAL GROWTH TO THE CLOUDS...SUGGESTIVE
OF SOME INSTABILITY. THERE HAS BEEN SOME SPOTTY CONVECTION ACROSS
NORTHEAST MO STRETCHING EAST THROUGH IL/CENTRAL IN BUT SOUTH OF THE
CWFA. DESPITE CONSIDERABLE SOLAR SHIELDING HAS BEEN ABLE TO KEEP
TEMPS IN THE 50S...WITH A FEW LOCATIONS BEING ABLE TO NUDGE TO ARND
60. WINDS WILL SHIFT NORTHWEST/NORTH BEHIND THE BOUNDARY WITH MUCH
DRIER/COOLER AIR STEADILY FILTERING INTO THE REGION OVERNIGHT.
PRECIP WILL COME TO AN END LATER THIS AFTN/EARLY EVE...WITH JUST A
FEW LINGERING SHOWERS ALONG AND EAST OF GIBSON CITY TO FOWLER. TEMPS
OVERNIGHT WILL COOL INTO THE LOW/MID 40S...WITH A FEW OF THE
TRADITIONALLY COOL SPOTS POSSIBLY DIPPING INTO THE UPR 30S BEFORE
DAYBREAK TUE. MEANWHILE CLOSER TO DOWNTOWN CHICAGO...THE URBAN HEAT
ISLAND SHUD AID IN KEEPING TEMPS IN THE UPR 40S TO ARND 50. THE ONLY
WILDCARD FOR OVERNIGHT LOWS WILL BE SKY COVER/WINDS...WHICH WITH
HIGH PRESSURE BUILDING IN SHUD ERODE/DIMINISH.

THERE IS ALSO SOME CONCERN THAT WITH THE LACK MIXING THIS AFTN AND
EXPECTED TEMPS BEING COOLER THAN AFTN DEW PTS...COUPLED WITH LIGHT
WINDS...COULD POINT TOWARDS PATCHY FOG DEVELOPING AWAY FROM THE
METRO AREA.

TUESDAY THROUGH THURSDAY...
RATHER BENIGN PATTERN FOR A GOOD PORTION OF THE WEEK. BROAD
ANTI-CYCLONIC FLOW WILL BUILD INTO THE REGION TUESDAY...WITH THE
MID-LVL TROUGH PIVOTING EAST. THE LONGWAVE PATTERN WILL LIKELY KEEP
THE REGION IN A CONTINUED NORTHWEST FLOW AS MID-LVL RIDGING RETURNS
TO THE WESTERN CONUS. GUIDANCE SUGGESTS THE SFC RIDGE THAT ARRIVES
TUE WILL SHIFT EAST...HOWEVER ANOTHER DOME OF HIGH PRESSURE FROM
CANADA IS THEN POISED TO SLIDE SOUTH AND CONTINUE THE DRY/COOL
WEATHER WED/THUR. TEMPS WILL GENERALLY REMAIN IN THE MID/UPR
60S...BUT POSSIBLY REACH 70 DEG IN SEVERAL AREAS FOR THUR. ABUNDANT
SUNSHINE IS EXPECTED EACH OF THE NEXT SEVERAL DAYS AS WELL.
OVERNIGHT LOWS WILL ALSO DIP INTO THE 40S TUE NGT/WED NGT...THEN
WITH THE SFC RIDGE BEGINNING TO PUSH EAST THUR NGT TEMPS COULD HOLD
ARND 50.

CONFIDENCE...HIGH.

FRIDAY THROUGH SUNDAY...
WITH THE SFC RIDGE POISED TO PUSH EAST OF THE REGION FRI...FLOW WILL
BE TURNING SOUTHERLY AND THE MID-LVL WAVE STARTING TO FLATTEN.
ENSEMBLES CONTINUE TO SHOW CONSIDERABLE SPREAD ON TIMING OF
PRECIP/MOISTURE RETURNING...WITH MOST MEMBERS POINTING TOWARDS FRI
NGT. THE ATMOSPHERE WILL MODERATE BY FRI/SAT WITH TEMPS IN THE
MID/UPR 70S...OR MORE SEASONAL. SAT APPEARS TO BE THE MOST FAVORABLE
PERIOD TO SEE SPOTTY SHOWERS/THUNDERSTORMS AS A MID-LVL TROUGH
DEVELOPS OVER THE CENTRAL PLAINS AND NEARS THE REGION SAT AFTN/EVE.
THEN FOR THE SECOND HALF OF THE WEEKEND SFC RIDGING IS PROGGED TO
RETURN TO THE REGION.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* N-NNE WINDS SETTLING BELOW 10 KT NEXT 1-2 HRS.

* MVFR CIGS SCATTERING/CLEARING TOWARD MID EVENING.

* LIGHT WEST TO NORTHWEST WINDS TUESDAY. LAKE BREEZE EXPECTED TO
  STAY TO THE EAST.

MDB

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

FRONTAL BOUNDARY IS NOW APPROACHING MDW AND WILL PASS GYY EARLY
THIS EVENING TURNING WINDS NORTHERLY WITH AN INITIAL INCREASE IN
SPEED TO 10-15 KT. SPEEDS WILL SETTLE UNDER 10 KT THROUGH EARLY
EVENING BEHIND THE FRONT THOUGH GYY MAY KEEP SPEEDS ABOVE 10 KT
INTO MID EVENING. SATELLITE SHOWS THE BACK EDGE OF THE MAIN CLOUD
SHIELD MOVING QUICKLY SOUTHEAST WITH THE DIURNAL STRATO CU TO THE
NORTHWEST QUICKLY DISSIPATING. EXPECT SKIES TO CLEAR BY MID
EVENING ACROSS THE IL TERMINALS WITH LAKE EFFECT PROCESSES
POTENTIALLY KEEPING MVFR CLOUDS AT GYY INTO THE OVERNIGHT. SOME
RESIDUAL LOW LEVEL MOISTURE MAY ALLOW FOR SOME PATCHY OR SHALLOW
FOG OVERNIGHT AT RFD/DPA AS WINDS DIMINISH. NORTHWEST WINDS WILL
BECOME WESTERLY UNDER 10 KT AT THE IL TERMINALS TUESDAY. A LAKE
BREEZE WILL LIKELY DEVELOP BY MIDDAY BRINGING NE WINDS TO GYY BUT
THE INLAND PUSH LOOKS TO BE SLOW GIVEN THE MINIMAL LAKE-LAND TEMP
DIFFERENCE SO WILL KEEP IT EAST OF ORD/MDW FOR NOW. SOME SCATTERED
STRATO CU IS EXPECTED TO DEVELOP LATE MORNING THEN LIFT/DISSIPATE
THROUGH THE AFTERNOON.

MDB

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

* MEDIUM-HIGH CONFIDENCE IN TIMING OF WINDS DROPPING BELOW 10 KT.

* HIGH CONFIDENCE IN MVFR CIGS SCATTERING/CLEARING...MEDIUM-HIGH
  CONFIDENCE IN TIMING.

* HIGH CONFIDENCE IN WEST TO NORTHWEST WINDS TUESDAY. MEDIUM-HIGH
  CONFIDENCE ANY LAKE BREEZE WILL REMAIN EAST.

MDB

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

WEDNESDAY...VFR. LIGHT WEST WINDS. LAKE BREEZE POSSIBLE.

THURSDAY...VFR. EAST WINDS.

FRIDAY...VFR. BREEZY SOUTH WINDS.

SATURDAY...CHANCE TSRA. MVFR POSSIBLE. BREEZY SOUTHWEST WINDS.

SUNDAY...SLIGHT CHANCE TSRA. VFR. WEST WINDS.

MDB

&&

.MARINE...
246 PM CDT

WEAK LOW PRESSURE WILL PUSH EAST THROUGH THE OHIO VALLEY AND
DISSIPATE THIS EVENING AS HIGH PRESSURE MOVES INTO THE MID
MISSOURI VALLEY TONIGHT. AHEAD OF THE HIGH A WEAK COLD FRONT WILL
SPREAD DOWN THE REMAINDER OF THE LAKE THIS EVENING AND BRIEFLY
INCREASE NORTH WINDS TO NEAR 20 KT THE HIGH WILL WEAKEN AND MOVE
OVER LAKE MICHIGAN ON TUESDAY. LOW PRESSURE OVER HUDSON BAY WILL
SPREAD INTO QUEBEC ON WEDNESDAY AS HIGH PRESSURE PUSHES SOUTH OUT
OF NORTHERN MANITOBA. AHEAD OF THE HIGH THE SOUTHWEST GRADIENT
INCREASES WITH WINDS 15 TO 25 KT FOR THE NORTH HALF OF THE LAKE. THE
HIGH REACHES LAKE SUPERIOR THURSDAY EVENING AND WILL PUSH A COLD
FRONT DOWN THE LAKE THURSDAY NIGHT. THIS HIGH WILL THEN MOVE TO
THE EASTERN LAKES BY LATE THURSDAY INTO FRIDAY AS SEVERAL LOWS
ORGANIZE IN THE CENTRAL PLAINS AND CANADIAN PRAIRIES.

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
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000
FXUS63 KLOT 152209
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
509 PM CDT MON SEP 15 2014

.DISCUSSION...
221 PM CDT

TONIGHT...
FRONTAL BOUNDARY THIS AFTERNOON CONTINUES TO SLIDE SOUTHEAST ACROSS
THE FORECAST AREA. VISIBLE IMAGERY ALONG AND JUST AHEAD OF THE
BOUNDARY INDICATED SOME VERTICAL GROWTH TO THE CLOUDS...SUGGESTIVE
OF SOME INSTABILITY. THERE HAS BEEN SOME SPOTTY CONVECTION ACROSS
NORTHEAST MO STRETCHING EAST THROUGH IL/CENTRAL IN BUT SOUTH OF THE
CWFA. DESPITE CONSIDERABLE SOLAR SHIELDING HAS BEEN ABLE TO KEEP
TEMPS IN THE 50S...WITH A FEW LOCATIONS BEING ABLE TO NUDGE TO ARND
60. WINDS WILL SHIFT NORTHWEST/NORTH BEHIND THE BOUNDARY WITH MUCH
DRIER/COOLER AIR STEADILY FILTERING INTO THE REGION OVERNIGHT.
PRECIP WILL COME TO AN END LATER THIS AFTN/EARLY EVE...WITH JUST A
FEW LINGERING SHOWERS ALONG AND EAST OF GIBSON CITY TO FOWLER. TEMPS
OVERNIGHT WILL COOL INTO THE LOW/MID 40S...WITH A FEW OF THE
TRADITIONALLY COOL SPOTS POSSIBLY DIPPING INTO THE UPR 30S BEFORE
DAYBREAK TUE. MEANWHILE CLOSER TO DOWNTOWN CHICAGO...THE URBAN HEAT
ISLAND SHUD AID IN KEEPING TEMPS IN THE UPR 40S TO ARND 50. THE ONLY
WILDCARD FOR OVERNIGHT LOWS WILL BE SKY COVER/WINDS...WHICH WITH
HIGH PRESSURE BUILDING IN SHUD ERODE/DIMINISH.

THERE IS ALSO SOME CONCERN THAT WITH THE LACK MIXING THIS AFTN AND
EXPECTED TEMPS BEING COOLER THAN AFTN DEW PTS...COUPLED WITH LIGHT
WINDS...COULD POINT TOWARDS PATCHY FOG DEVELOPING AWAY FROM THE
METRO AREA.

TUESDAY THROUGH THURSDAY...
RATHER BENIGN PATTERN FOR A GOOD PORTION OF THE WEEK. BROAD
ANTI-CYCLONIC FLOW WILL BUILD INTO THE REGION TUESDAY...WITH THE
MID-LVL TROUGH PIVOTING EAST. THE LONGWAVE PATTERN WILL LIKELY KEEP
THE REGION IN A CONTINUED NORTHWEST FLOW AS MID-LVL RIDGING RETURNS
TO THE WESTERN CONUS. GUIDANCE SUGGESTS THE SFC RIDGE THAT ARRIVES
TUE WILL SHIFT EAST...HOWEVER ANOTHER DOME OF HIGH PRESSURE FROM
CANADA IS THEN POISED TO SLIDE SOUTH AND CONTINUE THE DRY/COOL
WEATHER WED/THUR. TEMPS WILL GENERALLY REMAIN IN THE MID/UPR
60S...BUT POSSIBLY REACH 70 DEG IN SEVERAL AREAS FOR THUR. ABUNDANT
SUNSHINE IS EXPECTED EACH OF THE NEXT SEVERAL DAYS AS WELL.
OVERNIGHT LOWS WILL ALSO DIP INTO THE 40S TUE NGT/WED NGT...THEN
WITH THE SFC RIDGE BEGINNING TO PUSH EAST THUR NGT TEMPS COULD HOLD
ARND 50.

CONFIDENCE...HIGH.

FRIDAY THROUGH SUNDAY...
WITH THE SFC RIDGE POISED TO PUSH EAST OF THE REGION FRI...FLOW WILL
BE TURNING SOUTHERLY AND THE MID-LVL WAVE STARTING TO FLATTEN.
ENSEMBLES CONTINUE TO SHOW CONSIDERABLE SPREAD ON TIMING OF
PRECIP/MOISTURE RETURNING...WITH MOST MEMBERS POINTING TOWARDS FRI
NGT. THE ATMOSPHERE WILL MODERATE BY FRI/SAT WITH TEMPS IN THE
MID/UPR 70S...OR MORE SEASONAL. SAT APPEARS TO BE THE MOST FAVORABLE
PERIOD TO SEE SPOTTY SHOWERS/THUNDERSTORMS AS A MID-LVL TROUGH
DEVELOPS OVER THE CENTRAL PLAINS AND NEARS THE REGION SAT AFTN/EVE.
THEN FOR THE SECOND HALF OF THE WEEKEND SFC RIDGING IS PROGGED TO
RETURN TO THE REGION.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* FRONTAL BOUNDARY APPROACHING FROM NW PASSING ORD BY 2245-2300Z
  AND MDW BY 2330Z OR SO SHIFTING WINDS TO VARIABLE 350-020 WITH
  SPEEDS 10-12 KT WITH A FEW INITIAL GUSTS TO 15-17 KT POSSIBLE FOR
  A SHORT TIME.

* WINDS LIKELY FALL BELOW 10 KT 00-01Z.

* FRONT WILL BRING RETURN TO MVFR WITH -RA/DZ.

* SKIES CLEAR EARLY THIS EVENING.

MDB

//DISCUSSION...UPDATED 22Z...

FRONTAL BOUNDARY NOW APPROACHING ORD/DPA HEADING SOUTHEAST.
CONDITIONS IMPROVE TO VFR FOR A SHORT TIME RIGHT AHEAD OF THE
FRONT BUT MVFR RE-DEVELOPS WITH FRONTAL PASSAGE ALONG WITH -RA/DZ.
WINDS SHIFT TO NORTH WITH SOME VARIABILITY BUT SPEEDS TO INCREASE
TO 10-12 KT FOR AT LEAST A SHORT TIME. LIGHT RAIN/DRIZZLE WILL
LINGER FOR 1-2 HOURS BEHIND THE FRONT KEEPING CIGS DOWN BUT
GREATER VARIABILITY IN CIGS WILL LIKELY OCCUR AS SUNSET
APPROACHES...WITH CLEARING EARLY THIS EVENING. HAVE MADE SOME
ADJUSTMENTS TO ADD DETAIL TO TIMING OF CHANGES BASED ON LATEST
TRENDS.

MDB

FROM 18Z...

A COLD FRONT WILL SAG SOUTHWARD ACROSS NORTHERN ILLINOIS THROUGH
THE AFTERNOON. THIS WILL LEAD TO A NORTHERLY WIND SHIFT ACROSS THE
TERMINALS BY MID TO LATE THIS AFTERNOON. THE EASTERN TAF SITES
COULD EXPERIENCE A BIT MORE OF A NORTHEASTERLY COMPONENT.
HOWEVER...WIND SPEEDS OVERALL APPEAR THAT THEY MAY REMAIN AT OR
UNDER 10 KT WITH THIS NORTHERLY WIND SHIFT.

SCATTERED SHOWERS ARE ALSO EXPECTED ACROSS THE REGION OVER THE
NEXT SEVERAL HOURS AS THIS FRONT...AND AN UPPER LEVEL DISTURBANCE
MOVES OVER THE AREA. ALTHOUGH THESE SHOWERS WILL BE LIGHT...SOME
LOWER CIGS INTO THE LOWER MVFR RANGE MAY DEVELOP FOR A PERIOD THIS
AFTERNOON.

SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA TONIGHT INTO
TUESDAY. THIS WILL RESULT IN CLEARING SKIES THIS EVENING...AND
LIGHT WINDS INTO TUESDAY. SOME PATCHY FOG IS POSSIBLE
OVERNIGHT...MAINLY TO THE WEST AND SOUTH OF THE MAIN CHICAGO
TERMINALS. A LAKE BREEZE MAY DEVELOP ON TUESDAY AFTERNOON WITH THE
LIGHT WIND PATTERN. HOWEVER...CONFIDENCE ON HOW FAR INLAND THIS
FEATURE WOULD PUSH INLAND IS TOO LOW TO ADD A MENTION IN THE
LATEST 30 HOUR ORD TAF.

KJB

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

* HIGH CONFIDENCE IN TIMING OF FRONTAL PASSAGE. HIGH CONFIDENCE IN
  SHIFT TO 350-020 AND THAT WINDS WILL INCREASE TO 10-12 KT.
  MEDIUM CONFIDENCE IN DURATION/FREQUENCY OF 10+ KT WINDS.

* MEDIUM-HIGH CONFIDENCE IN WINDS FALLING BELOW 10 KT BY 01Z.

* HIGH CONFIDENCE IN CLEARING SKIES THIS EVENING...MEDIUM-HIGH
  CONFIDENCE IN TIMING.

MDB

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

TUESDAY NIGHT THROUGH FRIDAY...PRIMARILY VFR.
SATURDAY THROUGH SUNDAY...PERIODIC CHANCES FOR THUNDERSTORMS.

BMD

&&

.MARINE...
246 PM CDT

WEAK LOW PRESSURE WILL PUSH EAST THROUGH THE OHIO VALLEY AND
DISSIPATE THIS EVENING AS HIGH PRESSURE MOVES INTO THE MID
MISSOURI VALLEY TONIGHT. AHEAD OF THE HIGH A WEAK COLD FRONT WILL
SPREAD DOWN THE REMAINDER OF THE LAKE THIS EVENING AND BRIEFLY
INCREASE NORTH WINDS TO NEAR 20 KT THE HIGH WILL WEAKEN AND MOVE
OVER LAKE MICHIGAN ON TUESDAY. LOW PRESSURE OVER HUDSON BAY WILL
SPREAD INTO QUEBEC ON WEDNESDAY AS HIGH PRESSURE PUSHES SOUTH OUT
OF NORTHERN MANITOBA. AHEAD OF THE HIGH THE SOUTHWEST GRADIENT
INCREASES WITH WINDS 15 TO 25 KT FOR THE NORTH HALF OF THE LAKE. THE
HIGH REACHES LAKE SUPERIOR THURSDAY EVENING AND WILL PUSH A COLD
FRONT DOWN THE LAKE THURSDAY NIGHT. THIS HIGH WILL THEN MOVE TO
THE EASTERN LAKES BY LATE THURSDAY INTO FRIDAY AS SEVERAL LOWS
ORGANIZE IN THE CENTRAL PLAINS AND CANADIAN PRAIRIES.

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 152209
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
509 PM CDT MON SEP 15 2014

.DISCUSSION...
221 PM CDT

TONIGHT...
FRONTAL BOUNDARY THIS AFTERNOON CONTINUES TO SLIDE SOUTHEAST ACROSS
THE FORECAST AREA. VISIBLE IMAGERY ALONG AND JUST AHEAD OF THE
BOUNDARY INDICATED SOME VERTICAL GROWTH TO THE CLOUDS...SUGGESTIVE
OF SOME INSTABILITY. THERE HAS BEEN SOME SPOTTY CONVECTION ACROSS
NORTHEAST MO STRETCHING EAST THROUGH IL/CENTRAL IN BUT SOUTH OF THE
CWFA. DESPITE CONSIDERABLE SOLAR SHIELDING HAS BEEN ABLE TO KEEP
TEMPS IN THE 50S...WITH A FEW LOCATIONS BEING ABLE TO NUDGE TO ARND
60. WINDS WILL SHIFT NORTHWEST/NORTH BEHIND THE BOUNDARY WITH MUCH
DRIER/COOLER AIR STEADILY FILTERING INTO THE REGION OVERNIGHT.
PRECIP WILL COME TO AN END LATER THIS AFTN/EARLY EVE...WITH JUST A
FEW LINGERING SHOWERS ALONG AND EAST OF GIBSON CITY TO FOWLER. TEMPS
OVERNIGHT WILL COOL INTO THE LOW/MID 40S...WITH A FEW OF THE
TRADITIONALLY COOL SPOTS POSSIBLY DIPPING INTO THE UPR 30S BEFORE
DAYBREAK TUE. MEANWHILE CLOSER TO DOWNTOWN CHICAGO...THE URBAN HEAT
ISLAND SHUD AID IN KEEPING TEMPS IN THE UPR 40S TO ARND 50. THE ONLY
WILDCARD FOR OVERNIGHT LOWS WILL BE SKY COVER/WINDS...WHICH WITH
HIGH PRESSURE BUILDING IN SHUD ERODE/DIMINISH.

THERE IS ALSO SOME CONCERN THAT WITH THE LACK MIXING THIS AFTN AND
EXPECTED TEMPS BEING COOLER THAN AFTN DEW PTS...COUPLED WITH LIGHT
WINDS...COULD POINT TOWARDS PATCHY FOG DEVELOPING AWAY FROM THE
METRO AREA.

TUESDAY THROUGH THURSDAY...
RATHER BENIGN PATTERN FOR A GOOD PORTION OF THE WEEK. BROAD
ANTI-CYCLONIC FLOW WILL BUILD INTO THE REGION TUESDAY...WITH THE
MID-LVL TROUGH PIVOTING EAST. THE LONGWAVE PATTERN WILL LIKELY KEEP
THE REGION IN A CONTINUED NORTHWEST FLOW AS MID-LVL RIDGING RETURNS
TO THE WESTERN CONUS. GUIDANCE SUGGESTS THE SFC RIDGE THAT ARRIVES
TUE WILL SHIFT EAST...HOWEVER ANOTHER DOME OF HIGH PRESSURE FROM
CANADA IS THEN POISED TO SLIDE SOUTH AND CONTINUE THE DRY/COOL
WEATHER WED/THUR. TEMPS WILL GENERALLY REMAIN IN THE MID/UPR
60S...BUT POSSIBLY REACH 70 DEG IN SEVERAL AREAS FOR THUR. ABUNDANT
SUNSHINE IS EXPECTED EACH OF THE NEXT SEVERAL DAYS AS WELL.
OVERNIGHT LOWS WILL ALSO DIP INTO THE 40S TUE NGT/WED NGT...THEN
WITH THE SFC RIDGE BEGINNING TO PUSH EAST THUR NGT TEMPS COULD HOLD
ARND 50.

CONFIDENCE...HIGH.

FRIDAY THROUGH SUNDAY...
WITH THE SFC RIDGE POISED TO PUSH EAST OF THE REGION FRI...FLOW WILL
BE TURNING SOUTHERLY AND THE MID-LVL WAVE STARTING TO FLATTEN.
ENSEMBLES CONTINUE TO SHOW CONSIDERABLE SPREAD ON TIMING OF
PRECIP/MOISTURE RETURNING...WITH MOST MEMBERS POINTING TOWARDS FRI
NGT. THE ATMOSPHERE WILL MODERATE BY FRI/SAT WITH TEMPS IN THE
MID/UPR 70S...OR MORE SEASONAL. SAT APPEARS TO BE THE MOST FAVORABLE
PERIOD TO SEE SPOTTY SHOWERS/THUNDERSTORMS AS A MID-LVL TROUGH
DEVELOPS OVER THE CENTRAL PLAINS AND NEARS THE REGION SAT AFTN/EVE.
THEN FOR THE SECOND HALF OF THE WEEKEND SFC RIDGING IS PROGGED TO
RETURN TO THE REGION.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* FRONTAL BOUNDARY APPROACHING FROM NW PASSING ORD BY 2245-2300Z
  AND MDW BY 2330Z OR SO SHIFTING WINDS TO VARIABLE 350-020 WITH
  SPEEDS 10-12 KT WITH A FEW INITIAL GUSTS TO 15-17 KT POSSIBLE FOR
  A SHORT TIME.

* WINDS LIKELY FALL BELOW 10 KT 00-01Z.

* FRONT WILL BRING RETURN TO MVFR WITH -RA/DZ.

* SKIES CLEAR EARLY THIS EVENING.

MDB

//DISCUSSION...UPDATED 22Z...

FRONTAL BOUNDARY NOW APPROACHING ORD/DPA HEADING SOUTHEAST.
CONDITIONS IMPROVE TO VFR FOR A SHORT TIME RIGHT AHEAD OF THE
FRONT BUT MVFR RE-DEVELOPS WITH FRONTAL PASSAGE ALONG WITH -RA/DZ.
WINDS SHIFT TO NORTH WITH SOME VARIABILITY BUT SPEEDS TO INCREASE
TO 10-12 KT FOR AT LEAST A SHORT TIME. LIGHT RAIN/DRIZZLE WILL
LINGER FOR 1-2 HOURS BEHIND THE FRONT KEEPING CIGS DOWN BUT
GREATER VARIABILITY IN CIGS WILL LIKELY OCCUR AS SUNSET
APPROACHES...WITH CLEARING EARLY THIS EVENING. HAVE MADE SOME
ADJUSTMENTS TO ADD DETAIL TO TIMING OF CHANGES BASED ON LATEST
TRENDS.

MDB

FROM 18Z...

A COLD FRONT WILL SAG SOUTHWARD ACROSS NORTHERN ILLINOIS THROUGH
THE AFTERNOON. THIS WILL LEAD TO A NORTHERLY WIND SHIFT ACROSS THE
TERMINALS BY MID TO LATE THIS AFTERNOON. THE EASTERN TAF SITES
COULD EXPERIENCE A BIT MORE OF A NORTHEASTERLY COMPONENT.
HOWEVER...WIND SPEEDS OVERALL APPEAR THAT THEY MAY REMAIN AT OR
UNDER 10 KT WITH THIS NORTHERLY WIND SHIFT.

SCATTERED SHOWERS ARE ALSO EXPECTED ACROSS THE REGION OVER THE
NEXT SEVERAL HOURS AS THIS FRONT...AND AN UPPER LEVEL DISTURBANCE
MOVES OVER THE AREA. ALTHOUGH THESE SHOWERS WILL BE LIGHT...SOME
LOWER CIGS INTO THE LOWER MVFR RANGE MAY DEVELOP FOR A PERIOD THIS
AFTERNOON.

SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA TONIGHT INTO
TUESDAY. THIS WILL RESULT IN CLEARING SKIES THIS EVENING...AND
LIGHT WINDS INTO TUESDAY. SOME PATCHY FOG IS POSSIBLE
OVERNIGHT...MAINLY TO THE WEST AND SOUTH OF THE MAIN CHICAGO
TERMINALS. A LAKE BREEZE MAY DEVELOP ON TUESDAY AFTERNOON WITH THE
LIGHT WIND PATTERN. HOWEVER...CONFIDENCE ON HOW FAR INLAND THIS
FEATURE WOULD PUSH INLAND IS TOO LOW TO ADD A MENTION IN THE
LATEST 30 HOUR ORD TAF.

KJB

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

* HIGH CONFIDENCE IN TIMING OF FRONTAL PASSAGE. HIGH CONFIDENCE IN
  SHIFT TO 350-020 AND THAT WINDS WILL INCREASE TO 10-12 KT.
  MEDIUM CONFIDENCE IN DURATION/FREQUENCY OF 10+ KT WINDS.

* MEDIUM-HIGH CONFIDENCE IN WINDS FALLING BELOW 10 KT BY 01Z.

* HIGH CONFIDENCE IN CLEARING SKIES THIS EVENING...MEDIUM-HIGH
  CONFIDENCE IN TIMING.

MDB

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

TUESDAY NIGHT THROUGH FRIDAY...PRIMARILY VFR.
SATURDAY THROUGH SUNDAY...PERIODIC CHANCES FOR THUNDERSTORMS.

BMD

&&

.MARINE...
246 PM CDT

WEAK LOW PRESSURE WILL PUSH EAST THROUGH THE OHIO VALLEY AND
DISSIPATE THIS EVENING AS HIGH PRESSURE MOVES INTO THE MID
MISSOURI VALLEY TONIGHT. AHEAD OF THE HIGH A WEAK COLD FRONT WILL
SPREAD DOWN THE REMAINDER OF THE LAKE THIS EVENING AND BRIEFLY
INCREASE NORTH WINDS TO NEAR 20 KT THE HIGH WILL WEAKEN AND MOVE
OVER LAKE MICHIGAN ON TUESDAY. LOW PRESSURE OVER HUDSON BAY WILL
SPREAD INTO QUEBEC ON WEDNESDAY AS HIGH PRESSURE PUSHES SOUTH OUT
OF NORTHERN MANITOBA. AHEAD OF THE HIGH THE SOUTHWEST GRADIENT
INCREASES WITH WINDS 15 TO 25 KT FOR THE NORTH HALF OF THE LAKE. THE
HIGH REACHES LAKE SUPERIOR THURSDAY EVENING AND WILL PUSH A COLD
FRONT DOWN THE LAKE THURSDAY NIGHT. THIS HIGH WILL THEN MOVE TO
THE EASTERN LAKES BY LATE THURSDAY INTO FRIDAY AS SEVERAL LOWS
ORGANIZE IN THE CENTRAL PLAINS AND CANADIAN PRAIRIES.

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 152021
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
321 PM CDT Mon Sep 15 2014

.SHORT TERM...(Tonight)
ISSUED AT 321 PM CDT MON SEP 15 2014

Storm system still impacting Central Illinois ahead of an
approaching boundary.  Some low clouds and developing fog in the
wake of the showers hint to the main issues going into the overnight
hours tonight.  Showers and thunderstorms should begin to wrap up
this evening but wet, misty, and low clouds should continue for a
little while at least.  Satellite imagery showing the low clouds
hanging around a bit after the wind shift/boundary moves through
with the NW/N winds.  Cooler tonight...but coolest in the NW where
most likely to see some clearing.  Temps may bottom out locally if
the cigs clear in the overnight.  Either way, enhanced llvl moisture
will bring with it the chance for fog development.  For now,
question is between dense fog and very low stratus.  Stratus already
developing and see no reason to break that trend, so only putting in
patchy fog mention in the overnight hours.


&&

.LONG TERM...(Tuesday through Monday)
ISSUED AT 321 PM CDT MON SEP 15 2014

The medium and long range models are in generally good agreement
that a progressive upper level flow pattern will dominate through
the next seven days.

Surface high pressure from the northern Plains will work its way
toward the Midwest Tuesday, resulting in a clearing sky and a
continuation of cooler than normal temperatures. A weak shortwave
trough in the upper level northwest flow will approach the
mid-Missisippi River valley Wednesday. However, an abundance of dry
air in the lower levels should keep central and eastern IL
rain-free. Would not be surprised to see a sprinkle or two in areas
southwest of a Rushville-Springfield line. Will hold off on the
mention of that for now as the favorable moisture and lift appears
to stay along and west of the MS River.

Anticyclonic low level flow will continue to dominate through
Thursday and Friday keeping rain out of the forecast. A return,
southerly flow Friday will finally allow temperatures to climb
toward seasonal levels in the 75-80 range across most of central and
southeast IL.

Will keep the potential for showers and thunderstorms in the
forecast west of I-57 Saturday, and across all of central and
eastern IL Saturday night. The European and GFS models are actually
in quite good agreement that an upper level trough will advance from
the Rockies Friday to the Midwest later Saturday. The southerly low
level flow will advect plenty of moisture ahead of the surface cold
front, resulting in showers and thunderstorms. However, there is the
potential for heavy rain from this system, particularly according to
the GFS solution. The GFS depicts the remnants of Hurricane Odile,
currently in the southern California Baja region, ejecting toward
the central U.S. with deep tropical moisture. This would easily
result in 1-3" of rain across much of the forecast area Saturday
into early Sunday. However, the European and Canadian models are not
buying into this solution at the moment. As a result, will watch
this potential for the next several forecast runs before introducing
a mention of heavy rain.


&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 1245 PM CDT MON SEP 15 2014

Mostly IFR at terminals this afternoon. Conditions improving to
MVFR later this evening and through the night. Scattering out the
low clouds per time heights in both the GFS and the NAM as well as
HRRR.  At time of issuance, PIA cigs at 500 ft were isolated.
However, in the wake of the showers, GBG and C75 have both
dropped, which is in line with a progression of the IFR line
behind the showers. Concern that the IFR cigs will remain after
20z- 22z at the end of the tempos up to potentially 00z and will
likely be amending. Models clearing out the skies quicker will
assist in the potential for fog in the morning hours. Started the
trend, but conservative for now. VWP lighting up a LLWS issue with
some SW winds just off the deck at 35kts. Somewhat isolated, but
will amend accordingly.


&&

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

$$

SHORT TERM...HJS
LONG TERM...MILLER
AVIATION...HJS







000
FXUS63 KILX 152021
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
321 PM CDT Mon Sep 15 2014

.SHORT TERM...(Tonight)
ISSUED AT 321 PM CDT MON SEP 15 2014

Storm system still impacting Central Illinois ahead of an
approaching boundary.  Some low clouds and developing fog in the
wake of the showers hint to the main issues going into the overnight
hours tonight.  Showers and thunderstorms should begin to wrap up
this evening but wet, misty, and low clouds should continue for a
little while at least.  Satellite imagery showing the low clouds
hanging around a bit after the wind shift/boundary moves through
with the NW/N winds.  Cooler tonight...but coolest in the NW where
most likely to see some clearing.  Temps may bottom out locally if
the cigs clear in the overnight.  Either way, enhanced llvl moisture
will bring with it the chance for fog development.  For now,
question is between dense fog and very low stratus.  Stratus already
developing and see no reason to break that trend, so only putting in
patchy fog mention in the overnight hours.


&&

.LONG TERM...(Tuesday through Monday)
ISSUED AT 321 PM CDT MON SEP 15 2014

The medium and long range models are in generally good agreement
that a progressive upper level flow pattern will dominate through
the next seven days.

Surface high pressure from the northern Plains will work its way
toward the Midwest Tuesday, resulting in a clearing sky and a
continuation of cooler than normal temperatures. A weak shortwave
trough in the upper level northwest flow will approach the
mid-Missisippi River valley Wednesday. However, an abundance of dry
air in the lower levels should keep central and eastern IL
rain-free. Would not be surprised to see a sprinkle or two in areas
southwest of a Rushville-Springfield line. Will hold off on the
mention of that for now as the favorable moisture and lift appears
to stay along and west of the MS River.

Anticyclonic low level flow will continue to dominate through
Thursday and Friday keeping rain out of the forecast. A return,
southerly flow Friday will finally allow temperatures to climb
toward seasonal levels in the 75-80 range across most of central and
southeast IL.

Will keep the potential for showers and thunderstorms in the
forecast west of I-57 Saturday, and across all of central and
eastern IL Saturday night. The European and GFS models are actually
in quite good agreement that an upper level trough will advance from
the Rockies Friday to the Midwest later Saturday. The southerly low
level flow will advect plenty of moisture ahead of the surface cold
front, resulting in showers and thunderstorms. However, there is the
potential for heavy rain from this system, particularly according to
the GFS solution. The GFS depicts the remnants of Hurricane Odile,
currently in the southern California Baja region, ejecting toward
the central U.S. with deep tropical moisture. This would easily
result in 1-3" of rain across much of the forecast area Saturday
into early Sunday. However, the European and Canadian models are not
buying into this solution at the moment. As a result, will watch
this potential for the next several forecast runs before introducing
a mention of heavy rain.


&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 1245 PM CDT MON SEP 15 2014

Mostly IFR at terminals this afternoon. Conditions improving to
MVFR later this evening and through the night. Scattering out the
low clouds per time heights in both the GFS and the NAM as well as
HRRR.  At time of issuance, PIA cigs at 500 ft were isolated.
However, in the wake of the showers, GBG and C75 have both
dropped, which is in line with a progression of the IFR line
behind the showers. Concern that the IFR cigs will remain after
20z- 22z at the end of the tempos up to potentially 00z and will
likely be amending. Models clearing out the skies quicker will
assist in the potential for fog in the morning hours. Started the
trend, but conservative for now. VWP lighting up a LLWS issue with
some SW winds just off the deck at 35kts. Somewhat isolated, but
will amend accordingly.


&&

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

$$

SHORT TERM...HJS
LONG TERM...MILLER
AVIATION...HJS






000
FXUS63 KLOT 151953
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
253 PM CDT MON SEP 15 2014

.DISCUSSION...
221 PM CDT

TONIGHT...
FRONTAL BOUNDARY THIS AFTERNOON CONTINUES TO SLIDE SOUTHEAST ACROSS
THE FORECAST AREA. VISIBLE IMAGERY ALONG AND JUST AHEAD OF THE
BOUNDARY INDICATED SOME VERTICAL GROWTH TO THE CLOUDS...SUGGESTIVE
OF SOME INSTABILITY. THERE HAS BEEN SOME SPOTTY CONVECTION ACROSS
NORTHEAST MO STRETCHING EAST THROUGH IL/CENTRAL IN BUT SOUTH OF THE
CWFA. DESPITE CONSIDERABLE SOLAR SHIELDING HAS BEEN ABLE TO KEEP
TEMPS IN THE 50S...WITH A FEW LOCATIONS BEING ABLE TO NUDGE TO ARND
60. WINDS WILL SHIFT NORTHWEST/NORTH BEHIND THE BOUNDARY WITH MUCH
DRIER/COOLER AIR STEADILY FILTERING INTO THE REGION OVERNIGHT.
PRECIP WILL COME TO AN END LATER THIS AFTN/EARLY EVE...WITH JUST A
FEW LINGERING SHOWERS ALONG AND EAST OF GIBSON CITY TO FOWLER. TEMPS
OVERNIGHT WILL COOL INTO THE LOW/MID 40S...WITH A FEW OF THE
TRADITIONALLY COOL SPOTS POSSIBLY DIPPING INTO THE UPR 30S BEFORE
DAYBREAK TUE. MEANWHILE CLOSER TO DOWNTOWN CHICAGO...THE URBAN HEAT
ISLAND SHUD AID IN KEEPING TEMPS IN THE UPR 40S TO ARND 50. THE ONLY
WILDCARD FOR OVERNIGHT LOWS WILL BE SKY COVER/WINDS...WHICH WITH
HIGH PRESSURE BUILDING IN SHUD ERODE/DIMINISH.

THERE IS ALSO SOME CONCERN THAT WITH THE LACK MIXING THIS AFTN AND
EXPECTED TEMPS BEING COOLER THAN AFTN DEW PTS...COUPLED WITH LIGHT
WINDS...COULD POINT TOWARDS PATCHY FOG DEVELOPING AWAY FROM THE
METRO AREA.

TUESDAY THROUGH THURSDAY...
RATHER BENIGN PATTERN FOR A GOOD PORTION OF THE WEEK. BROAD
ANTI-CYCLONIC FLOW WILL BUILD INTO THE REGION TUESDAY...WITH THE
MID-LVL TROUGH PIVOTING EAST. THE LONGWAVE PATTERN WILL LIKELY KEEP
THE REGION IN A CONTINUED NORTHWEST FLOW AS MID-LVL RIDGING RETURNS
TO THE WESTERN CONUS. GUIDANCE SUGGESTS THE SFC RIDGE THAT ARRIVES
TUE WILL SHIFT EAST...HOWEVER ANOTHER DOME OF HIGH PRESSURE FROM
CANADA IS THEN POISED TO SLIDE SOUTH AND CONTINUE THE DRY/COOL
WEATHER WED/THUR. TEMPS WILL GENERALLY REMAIN IN THE MID/UPR
60S...BUT POSSIBLY REACH 70 DEG IN SEVERAL AREAS FOR THUR. ABUNDANT
SUNSHINE IS EXPECTED EACH OF THE NEXT SEVERAL DAYS AS WELL.
OVERNIGHT LOWS WILL ALSO DIP INTO THE 40S TUE NGT/WED NGT...THEN
WITH THE SFC RIDGE BEGINNING TO PUSH EAST THUR NGT TEMPS COULD HOLD
ARND 50.

CONFIDENCE...HIGH.

FRIDAY THROUGH SUNDAY...
WITH THE SFC RIDGE POISED TO PUSH EAST OF THE REGION FRI...FLOW WILL
BE TURNING SOUTHERLY AND THE MID-LVL WAVE STARTING TO FLATTEN.
ENSEMBLES CONTINUE TO SHOW CONSIDERABLE SPREAD ON TIMING OF
PRECIP/MOISTURE RETURNING...WITH MOST MEMBERS POINTING TOWARDS FRI
NGT. THE ATMOSPHERE WILL MODERATE BY FRI/SAT WITH TEMPS IN THE
MID/UPR 70S...OR MORE SEASONAL. SAT APPEARS TO BE THE MOST FAVORABLE
PERIOD TO SEE SPOTTY SHOWERS/THUNDERSTORMS AS A MID-LVL TROUGH
DEVELOPS OVER THE CENTRAL PLAINS AND NEARS THE REGION SAT AFTN/EVE.
THEN FOR THE SECOND HALF OF THE WEEKEND SFC RIDGING IS PROGGED TO
RETURN TO THE REGION.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* WIND DIRECTION AND SPEEDS ASSOCIATED WITH FROPA LATE THIS
  AFTERNOON ...NORTH-NORTHEAST WIND LOOKING LIKELY...WIND SPEEDS
  COULD REMAIN UNDER 10 KT.
* CIGS LOWERING TO MVFR WITH SHRA.

KJB

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

A COLD FRONT WILL SAG SOUTHWARD ACROSS NORTHERN ILLINOIS THROUGH
THE AFTERNOON. THIS WILL LEAD TO A NORTHERLY WIND SHIFT ACROSS THE
TERMINALS BY MID TO LATE THIS AFTERNOON. THE EASTERN TAF SITES
COULD EXPERIENCE A BIT MORE OF A NORTHEASTERLY COMPONENT.
HOWEVER...WIND SPEEDS OVERALL APPEAR THAT THEY MAY REMAIN AT OR
UNDER 10 KT WITH THIS NORTHERLY WIND SHIFT.

SCATTERED SHOWERS ARE ALSO EXPECTED ACROSS THE REGION OVER THE
NEXT SEVERAL HOURS AS THIS FRONT...AND AN UPPER LEVEL DISTURBANCE
MOVES OVER THE AREA. ALTHOUGH THESE SHOWERS WILL BE LIGHT...SOME
LOWER CIGS INTO THE LOWER MVFR RANGE MAY DEVELOP FOR A PERIOD THIS
AFTERNOON.

SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA TONIGHT INTO
TUESDAY. THIS WILL RESULT IN CLEARING SKIES THIS EVENING...AND
LIGHT WINDS INTO TUESDAY. SOME PATCHY FOG IS POSSIBLE
OVERNIGHT...MAINLY TO THE WEST AND SOUTH OF THE MAIN CHICAGO
TERMINALS. A LAKE BREEZE MAY DEVELOP ON TUESDAY AFTERNOON WITH THE
LIGHT WIND PATTERN. HOWEVER...CONFIDENCE ON HOW FAR INLAND THIS
FEATURE WOULD PUSH INLAND IS TOO LOW TO ADD A MENTION IN THE
LATEST 30 HOUR ORD TAF.

KJB

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

* MEDIUM TO HIGH CONFIDENCE IN WIND DIRECTION...LOW-MEDIUM THAT WINDS
  WILL GET AS HIGH AS 10 KT LATE THIS AFTERNOON.
* MEDIUM CONFIDENCE IN SHRA/MVFR TIMING.

KJB

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

TUESDAY NIGHT THROUGH FRIDAY...PRIMARILY VFR.
SATURDAY THROUGH SUNDAY...PERIODIC CHANCES FOR THUNDERSTORMS.

BMD

&&

.MARINE...
246 PM CDT

WEAK LOW PRESSURE WILL PUSH EAST THROUGH THE OHIO VALLEY AND
DISSIPATE THIS EVENING AS HIGH PRESSURE MOVES INTO THE MID
MISSOURI VALLEY TONIGHT. AHEAD OF THE HIGH A WEAK COLD FRONT WILL
SPREAD DOWN THE REMAINDER OF THE LAKE THIS EVENING AND BRIEFLY
INCREASE NORTH WINDS TO NEAR 20 KT THE HIGH WILL WEAKEN AND MOVE
OVER LAKE MICHIGAN ON TUESDAY. LOW PRESSURE OVER HUDSON BAY WILL
SPREAD INTO QUEBEC ON WEDNESDAY AS HIGH PRESSURE PUSHES SOUTH OUT
OF NORTHERN MANITOBA. AHEAD OF THE HIGH THE SOUTHWEST GRADIENT
INCREASES WITH WINDS 15 TO 25 KT FOR THE NORTH HALF OF THE LAKE. THE
HIGH REACHES LAKE SUPERIOR THURSDAY EVENING AND WILL PUSH A COLD
FRONT DOWN THE LAKE THURSDAY NIGHT. THIS HIGH WILL THEN MOVE TO
THE EASTERN LAKES BY LATE THURSDAY INTO FRIDAY AS SEVERAL LOWS
ORGANIZE IN THE CENTRAL PLAINS AND CANADIAN PRAIRIES.

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 151953
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
253 PM CDT MON SEP 15 2014

.DISCUSSION...
221 PM CDT

TONIGHT...
FRONTAL BOUNDARY THIS AFTERNOON CONTINUES TO SLIDE SOUTHEAST ACROSS
THE FORECAST AREA. VISIBLE IMAGERY ALONG AND JUST AHEAD OF THE
BOUNDARY INDICATED SOME VERTICAL GROWTH TO THE CLOUDS...SUGGESTIVE
OF SOME INSTABILITY. THERE HAS BEEN SOME SPOTTY CONVECTION ACROSS
NORTHEAST MO STRETCHING EAST THROUGH IL/CENTRAL IN BUT SOUTH OF THE
CWFA. DESPITE CONSIDERABLE SOLAR SHIELDING HAS BEEN ABLE TO KEEP
TEMPS IN THE 50S...WITH A FEW LOCATIONS BEING ABLE TO NUDGE TO ARND
60. WINDS WILL SHIFT NORTHWEST/NORTH BEHIND THE BOUNDARY WITH MUCH
DRIER/COOLER AIR STEADILY FILTERING INTO THE REGION OVERNIGHT.
PRECIP WILL COME TO AN END LATER THIS AFTN/EARLY EVE...WITH JUST A
FEW LINGERING SHOWERS ALONG AND EAST OF GIBSON CITY TO FOWLER. TEMPS
OVERNIGHT WILL COOL INTO THE LOW/MID 40S...WITH A FEW OF THE
TRADITIONALLY COOL SPOTS POSSIBLY DIPPING INTO THE UPR 30S BEFORE
DAYBREAK TUE. MEANWHILE CLOSER TO DOWNTOWN CHICAGO...THE URBAN HEAT
ISLAND SHUD AID IN KEEPING TEMPS IN THE UPR 40S TO ARND 50. THE ONLY
WILDCARD FOR OVERNIGHT LOWS WILL BE SKY COVER/WINDS...WHICH WITH
HIGH PRESSURE BUILDING IN SHUD ERODE/DIMINISH.

THERE IS ALSO SOME CONCERN THAT WITH THE LACK MIXING THIS AFTN AND
EXPECTED TEMPS BEING COOLER THAN AFTN DEW PTS...COUPLED WITH LIGHT
WINDS...COULD POINT TOWARDS PATCHY FOG DEVELOPING AWAY FROM THE
METRO AREA.

TUESDAY THROUGH THURSDAY...
RATHER BENIGN PATTERN FOR A GOOD PORTION OF THE WEEK. BROAD
ANTI-CYCLONIC FLOW WILL BUILD INTO THE REGION TUESDAY...WITH THE
MID-LVL TROUGH PIVOTING EAST. THE LONGWAVE PATTERN WILL LIKELY KEEP
THE REGION IN A CONTINUED NORTHWEST FLOW AS MID-LVL RIDGING RETURNS
TO THE WESTERN CONUS. GUIDANCE SUGGESTS THE SFC RIDGE THAT ARRIVES
TUE WILL SHIFT EAST...HOWEVER ANOTHER DOME OF HIGH PRESSURE FROM
CANADA IS THEN POISED TO SLIDE SOUTH AND CONTINUE THE DRY/COOL
WEATHER WED/THUR. TEMPS WILL GENERALLY REMAIN IN THE MID/UPR
60S...BUT POSSIBLY REACH 70 DEG IN SEVERAL AREAS FOR THUR. ABUNDANT
SUNSHINE IS EXPECTED EACH OF THE NEXT SEVERAL DAYS AS WELL.
OVERNIGHT LOWS WILL ALSO DIP INTO THE 40S TUE NGT/WED NGT...THEN
WITH THE SFC RIDGE BEGINNING TO PUSH EAST THUR NGT TEMPS COULD HOLD
ARND 50.

CONFIDENCE...HIGH.

FRIDAY THROUGH SUNDAY...
WITH THE SFC RIDGE POISED TO PUSH EAST OF THE REGION FRI...FLOW WILL
BE TURNING SOUTHERLY AND THE MID-LVL WAVE STARTING TO FLATTEN.
ENSEMBLES CONTINUE TO SHOW CONSIDERABLE SPREAD ON TIMING OF
PRECIP/MOISTURE RETURNING...WITH MOST MEMBERS POINTING TOWARDS FRI
NGT. THE ATMOSPHERE WILL MODERATE BY FRI/SAT WITH TEMPS IN THE
MID/UPR 70S...OR MORE SEASONAL. SAT APPEARS TO BE THE MOST FAVORABLE
PERIOD TO SEE SPOTTY SHOWERS/THUNDERSTORMS AS A MID-LVL TROUGH
DEVELOPS OVER THE CENTRAL PLAINS AND NEARS THE REGION SAT AFTN/EVE.
THEN FOR THE SECOND HALF OF THE WEEKEND SFC RIDGING IS PROGGED TO
RETURN TO THE REGION.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

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

* WIND DIRECTION AND SPEEDS ASSOCIATED WITH FROPA LATE THIS
  AFTERNOON ...NORTH-NORTHEAST WIND LOOKING LIKELY...WIND SPEEDS
  COULD REMAIN UNDER 10 KT.
* CIGS LOWERING TO MVFR WITH SHRA.

KJB

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

A COLD FRONT WILL SAG SOUTHWARD ACROSS NORTHERN ILLINOIS THROUGH
THE AFTERNOON. THIS WILL LEAD TO A NORTHERLY WIND SHIFT ACROSS THE
TERMINALS BY MID TO LATE THIS AFTERNOON. THE EASTERN TAF SITES
COULD EXPERIENCE A BIT MORE OF A NORTHEASTERLY COMPONENT.
HOWEVER...WIND SPEEDS OVERALL APPEAR THAT THEY MAY REMAIN AT OR
UNDER 10 KT WITH THIS NORTHERLY WIND SHIFT.

SCATTERED SHOWERS ARE ALSO EXPECTED ACROSS THE REGION OVER THE
NEXT SEVERAL HOURS AS THIS FRONT...AND AN UPPER LEVEL DISTURBANCE
MOVES OVER THE AREA. ALTHOUGH THESE SHOWERS WILL BE LIGHT...SOME
LOWER CIGS INTO THE LOWER MVFR RANGE MAY DEVELOP FOR A PERIOD THIS
AFTERNOON.

SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA TONIGHT INTO
TUESDAY. THIS WILL RESULT IN CLEARING SKIES THIS EVENING...AND
LIGHT WINDS INTO TUESDAY. SOME PATCHY FOG IS POSSIBLE
OVERNIGHT...MAINLY TO THE WEST AND SOUTH OF THE MAIN CHICAGO
TERMINALS. A LAKE BREEZE MAY DEVELOP ON TUESDAY AFTERNOON WITH THE
LIGHT WIND PATTERN. HOWEVER...CONFIDENCE ON HOW FAR INLAND THIS
FEATURE WOULD PUSH INLAND IS TOO LOW TO ADD A MENTION IN THE
LATEST 30 HOUR ORD TAF.

KJB

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

* MEDIUM TO HIGH CONFIDENCE IN WIND DIRECTION...LOW-MEDIUM THAT WINDS
  WILL GET AS HIGH AS 10 KT LATE THIS AFTERNOON.
* MEDIUM CONFIDENCE IN SHRA/MVFR TIMING.

KJB

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

TUESDAY NIGHT THROUGH FRIDAY...PRIMARILY VFR.
SATURDAY THROUGH SUNDAY...PERIODIC CHANCES FOR THUNDERSTORMS.

BMD

&&

.MARINE...
246 PM CDT

WEAK LOW PRESSURE WILL PUSH EAST THROUGH THE OHIO VALLEY AND
DISSIPATE THIS EVENING AS HIGH PRESSURE MOVES INTO THE MID
MISSOURI VALLEY TONIGHT. AHEAD OF THE HIGH A WEAK COLD FRONT WILL
SPREAD DOWN THE REMAINDER OF THE LAKE THIS EVENING AND BRIEFLY
INCREASE NORTH WINDS TO NEAR 20 KT THE HIGH WILL WEAKEN AND MOVE
OVER LAKE MICHIGAN ON TUESDAY. LOW PRESSURE OVER HUDSON BAY WILL
SPREAD INTO QUEBEC ON WEDNESDAY AS HIGH PRESSURE PUSHES SOUTH OUT
OF NORTHERN MANITOBA. AHEAD OF THE HIGH THE SOUTHWEST GRADIENT
INCREASES WITH WINDS 15 TO 25 KT FOR THE NORTH HALF OF THE LAKE. THE
HIGH REACHES LAKE SUPERIOR THURSDAY EVENING AND WILL PUSH A COLD
FRONT DOWN THE LAKE THURSDAY NIGHT. THIS HIGH WILL THEN MOVE TO
THE EASTERN LAKES BY LATE THURSDAY INTO FRIDAY AS SEVERAL LOWS
ORGANIZE IN THE CENTRAL PLAINS AND CANADIAN PRAIRIES.

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 151951
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
251 PM CDT MON SEP 15 2014

.DISCUSSION...
221 PM CDT

TONIGHT...
FRONTAL BOUNDARY THIS AFTERNOON CONTINUES TO SLIDE SOUTHEAST ACROSS
THE FORECAST AREA. VISIBLE IMAGERY ALONG AND JUST AHEAD OF THE
BOUNDARY INDICATED SOME VERTICAL GROWTH TO THE CLOUDS...SUGGESTIVE
OF SOME INSTABILITY. THERE HAS BEEN SOME SPOTTY CONVECTION ACROSS
NORTHEAST MO STRETCHING EAST THROUGH IL/CENTRAL IN BUT SOUTH OF THE
CWFA. DESPITE CONSIDERABLE SOLAR SHIELDING HAS BEEN ABLE TO KEEP
TEMPS IN THE 50S...WITH A FEW LOCATIONS BEING ABLE TO NUDGE TO ARND
60. WINDS WILL SHIFT NORTHWEST/NORTH BEHIND THE BOUNDARY WITH MUCH
DRIER/COOLER AIR STEADILY FILTERING INTO THE REGION OVERNIGHT.
PRECIP WILL COME TO AN END LATER THIS AFTN/EARLY EVE...WITH JUST A
FEW LINGERING SHOWERS ALONG AND EAST OF GIBSON CITY TO FOWLER. TEMPS
OVERNIGHT WILL COOL INTO THE LOW/MID 40S...WITH A FEW OF THE
TRADITIONALLY COOL SPOTS POSSIBLY DIPPING INTO THE UPR 30S BEFORE
DAYBREAK TUE. MEANWHILE CLOSER TO DOWNTOWN CHICAGO...THE URBAN HEAT
ISLAND SHUD AID IN KEEPING TEMPS IN THE UPR 40S TO ARND 50. THE ONLY
WILDCARD FOR OVERNIGHT LOWS WILL BE SKY COVER/WINDS...WHICH WITH
HIGH PRESSURE BUILDING IN SHUD ERODE/DIMINISH.

THERE IS ALSO SOME CONCERN THAT WITH THE LACK MIXING THIS AFTN AND
EXPECTED TEMPS BEING COOLER THAN AFTN DEW PTS...COUPLED WITH LIGHT
WINDS...COULD POINT TOWARDS PATCHY FOG DEVELOPING AWAY FROM THE
METRO AREA.

TUESDAY THROUGH THURSDAY...
RATHER BENIGN PATTERN FOR A GOOD PORTION OF THE WEEK. BROAD
ANTI-CYCLONIC FLOW WILL BUILD INTO THE REGION TUESDAY...WITH THE
MID-LVL TROUGH PIVOTING EAST. THE LONGWAVE PATTERN WILL LIKELY KEEP
THE REGION IN A CONTINUED NORTHWEST FLOW AS MID-LVL RIDGING RETURNS
TO THE WESTERN CONUS. GUIDANCE SUGGESTS THE SFC RIDGE THAT ARRIVES
TUE WILL SHIFT EAST...HOWEVER ANOTHER DOME OF HIGH PRESSURE FROM
CANADA IS THEN POISED TO SLIDE SOUTH AND CONTINUE THE DRY/COOL
WEATHER WED/THUR. TEMPS WILL GENERALLY REMAIN IN THE MID/UPR
60S...BUT POSSIBLY REACH 70 DEG IN SEVERAL AREAS FOR THUR. ABUNDANT
SUNSHINE IS EXPECTED EACH OF THE NEXT SEVERAL DAYS AS WELL.
OVERNIGHT LOWS WILL ALSO DIP INTO THE 40S TUE NGT/WED NGT...THEN
WITH THE SFC RIDGE BEGINNING TO PUSH EAST THUR NGT TEMPS COULD HOLD
ARND 50.

CONFIDENCE...HIGH.

FRIDAY THROUGH SUNDAY...
WITH THE SFC RIDGE POISED TO PUSH EAST OF THE REGION FRI...FLOW WILL
BE TURNING SOUTHERLY AND THE MID-LVL WAVE STARTING TO FLATTEN.
ENSEMBLES CONTINUE TO SHOW CONSIDERABLE SPREAD ON TIMING OF
PRECIP/MOISTURE RETURNING...WITH MOST MEMBERS POINTING TOWARDS FRI
NGT. THE ATMOSPHERE WILL MODERATE BY FRI/SAT WITH TEMPS IN THE
MID/UPR 70S...OR MORE SEASONAL. SAT APPEARS TO BE THE MOST FAVORABLE
PERIOD TO SEE SPOTTY SHOWERS/THUNDERSTORMS AS A MID-LVL TROUGH
DEVELOPS OVER THE CENTRAL PLAINS AND NEARS THE REGION SAT AFTN/EVE.
THEN FOR THE SECOND HALF OF THE WEEKEND SFC RIDGING IS PROGGED TO
RETURN TO THE REGION.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* WIND DIRECTION AND SPEEDS ASSOCIATED WITH FROPA THIS AFTERNOON
  ...NORTH-NORTHEAST WIND LOOKING LIKELY BY LATE AFTERNOON...WIND
  SPEEDS COULD REMAIN UNDER 10 KT.
* CIGS LOWERING TO MVFR WITH SHRA.

KJB

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

A COLD FRONT WILL SAG SOUTHWARD ACROSS NORTHERN ILLINOIS THROUGH
THE AFTERNOON. THIS WILL LEAD TO A NORTHERLY WIND SHIFT ACROSS THE
TERMINALS BY MID TO LATE THIS AFTERNOON. THE EASTERN TAF SITES
COULD EXPERIENCE A BIT MORE OF A NORTHEASTERLY COMPONENT.
HOWEVER...WIND SPEEDS OVERALL APPEAR THAT THEY MAY REMAIN AT OR
UNDER 10 KT WITH THIS NORTHERLY WIND SHIFT.

SCATTERED SHOWERS ARE ALSO EXPECTED ACROSS THE REGION OVER THE
NEXT SEVERAL HOURS AS THIS FRONT...AND AN UPPER LEVEL DISTURBANCE
MOVES OVER THE AREA. ALTHOUGH THESE SHOWERS WILL BE LIGHT...SOME
LOWER CIGS INTO THE LOWER MVFR RANGE MAY DEVELOP FOR A PERIOD THIS
AFTERNOON.

SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA TONIGHT INTO
TUESDAY. THIS WILL RESULT IN CLEARING SKIES THIS EVENING...AND
LIGHT WINDS INTO TUESDAY. SOME PATCHY FOG IS POSSIBLE
OVERNIGHT...MAINLY TO THE WEST AND SOUTH OF THE MAIN CHICAGO
TERMINALS. A LAKE BREEZE MAY DEVELOP ON TUESDAY AFTERNOON WITH THE
LIGHT WIND PATTERN. HOWEVER...CONFIDENCE ON HOW FAR INLAND THIS
FEATURE WOULD PUSH INLAND IS TOO LOW TO ADD A MENTION IN THE
LATEST 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM TO HIGH CONFIDENCE IN WIND DIRECTION...LOW-MEDIUM THAT WINDS
  WILL GET AS HIGH AS 10 KT LATE THIS AFTERNOON.
* LOW-MEDIUM CONFIDENCE IN SHRA/MVFR TIMING.

KJB

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

TUESDAY NIGHT THROUGH FRIDAY...PRIMARILY VFR.
SATURDAY THROUGH SUNDAY...PERIODIC CHANCES FOR THUNDERSTORMS.

BMD

&&

.MARINE...
246 PM CDT

WEAK LOW PRESSURE WILL PUSH EAST THROUGH THE OHIO VALLEY AND
DISSIPATE THIS EVENING AS HIGH PRESSURE MOVES INTO THE MID
MISSOURI VALLEY TONIGHT. AHEAD OF THE HIGH A WEAK COLD FRONT WILL
SPREAD DOWN THE REMAINDER OF THE LAKE THIS EVENING AND BRIEFLY
INCREASE NORTH WINDS TO NEAR 20 KT THE HIGH WILL WEAKEN AND MOVE
OVER LAKE MICHIGAN ON TUESDAY. LOW PRESSURE OVER HUDSON BAY WILL
SPREAD INTO QUEBEC ON WEDNESDAY AS HIGH PRESSURE PUSHES SOUTH OUT
OF NORTHERN MANITOBA. AHEAD OF THE HIGH THE SOUTHWEST GRADIENT
INCREASES WITH WINDS 15 TO 25 KT FOR THE NORTH HALF OF THE LAKE. THE
HIGH REACHES LAKE SUPERIOR THURSDAY EVENING AND WILL PUSH A COLD
FRONT DOWN THE LAKE THURSDAY NIGHT. THIS HIGH WILL THEN MOVE TO
THE EASTERN LAKES BY LATE THURSDAY INTO FRIDAY AS SEVERAL LOWS
ORGANIZE IN THE CENTRAL PLAINS AND CANADIAN PRAIRIES.

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 151951
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
251 PM CDT MON SEP 15 2014

.DISCUSSION...
221 PM CDT

TONIGHT...
FRONTAL BOUNDARY THIS AFTERNOON CONTINUES TO SLIDE SOUTHEAST ACROSS
THE FORECAST AREA. VISIBLE IMAGERY ALONG AND JUST AHEAD OF THE
BOUNDARY INDICATED SOME VERTICAL GROWTH TO THE CLOUDS...SUGGESTIVE
OF SOME INSTABILITY. THERE HAS BEEN SOME SPOTTY CONVECTION ACROSS
NORTHEAST MO STRETCHING EAST THROUGH IL/CENTRAL IN BUT SOUTH OF THE
CWFA. DESPITE CONSIDERABLE SOLAR SHIELDING HAS BEEN ABLE TO KEEP
TEMPS IN THE 50S...WITH A FEW LOCATIONS BEING ABLE TO NUDGE TO ARND
60. WINDS WILL SHIFT NORTHWEST/NORTH BEHIND THE BOUNDARY WITH MUCH
DRIER/COOLER AIR STEADILY FILTERING INTO THE REGION OVERNIGHT.
PRECIP WILL COME TO AN END LATER THIS AFTN/EARLY EVE...WITH JUST A
FEW LINGERING SHOWERS ALONG AND EAST OF GIBSON CITY TO FOWLER. TEMPS
OVERNIGHT WILL COOL INTO THE LOW/MID 40S...WITH A FEW OF THE
TRADITIONALLY COOL SPOTS POSSIBLY DIPPING INTO THE UPR 30S BEFORE
DAYBREAK TUE. MEANWHILE CLOSER TO DOWNTOWN CHICAGO...THE URBAN HEAT
ISLAND SHUD AID IN KEEPING TEMPS IN THE UPR 40S TO ARND 50. THE ONLY
WILDCARD FOR OVERNIGHT LOWS WILL BE SKY COVER/WINDS...WHICH WITH
HIGH PRESSURE BUILDING IN SHUD ERODE/DIMINISH.

THERE IS ALSO SOME CONCERN THAT WITH THE LACK MIXING THIS AFTN AND
EXPECTED TEMPS BEING COOLER THAN AFTN DEW PTS...COUPLED WITH LIGHT
WINDS...COULD POINT TOWARDS PATCHY FOG DEVELOPING AWAY FROM THE
METRO AREA.

TUESDAY THROUGH THURSDAY...
RATHER BENIGN PATTERN FOR A GOOD PORTION OF THE WEEK. BROAD
ANTI-CYCLONIC FLOW WILL BUILD INTO THE REGION TUESDAY...WITH THE
MID-LVL TROUGH PIVOTING EAST. THE LONGWAVE PATTERN WILL LIKELY KEEP
THE REGION IN A CONTINUED NORTHWEST FLOW AS MID-LVL RIDGING RETURNS
TO THE WESTERN CONUS. GUIDANCE SUGGESTS THE SFC RIDGE THAT ARRIVES
TUE WILL SHIFT EAST...HOWEVER ANOTHER DOME OF HIGH PRESSURE FROM
CANADA IS THEN POISED TO SLIDE SOUTH AND CONTINUE THE DRY/COOL
WEATHER WED/THUR. TEMPS WILL GENERALLY REMAIN IN THE MID/UPR
60S...BUT POSSIBLY REACH 70 DEG IN SEVERAL AREAS FOR THUR. ABUNDANT
SUNSHINE IS EXPECTED EACH OF THE NEXT SEVERAL DAYS AS WELL.
OVERNIGHT LOWS WILL ALSO DIP INTO THE 40S TUE NGT/WED NGT...THEN
WITH THE SFC RIDGE BEGINNING TO PUSH EAST THUR NGT TEMPS COULD HOLD
ARND 50.

CONFIDENCE...HIGH.

FRIDAY THROUGH SUNDAY...
WITH THE SFC RIDGE POISED TO PUSH EAST OF THE REGION FRI...FLOW WILL
BE TURNING SOUTHERLY AND THE MID-LVL WAVE STARTING TO FLATTEN.
ENSEMBLES CONTINUE TO SHOW CONSIDERABLE SPREAD ON TIMING OF
PRECIP/MOISTURE RETURNING...WITH MOST MEMBERS POINTING TOWARDS FRI
NGT. THE ATMOSPHERE WILL MODERATE BY FRI/SAT WITH TEMPS IN THE
MID/UPR 70S...OR MORE SEASONAL. SAT APPEARS TO BE THE MOST FAVORABLE
PERIOD TO SEE SPOTTY SHOWERS/THUNDERSTORMS AS A MID-LVL TROUGH
DEVELOPS OVER THE CENTRAL PLAINS AND NEARS THE REGION SAT AFTN/EVE.
THEN FOR THE SECOND HALF OF THE WEEKEND SFC RIDGING IS PROGGED TO
RETURN TO THE REGION.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* WIND DIRECTION AND SPEEDS ASSOCIATED WITH FROPA THIS AFTERNOON
  ...NORTH-NORTHEAST WIND LOOKING LIKELY BY LATE AFTERNOON...WIND
  SPEEDS COULD REMAIN UNDER 10 KT.
* CIGS LOWERING TO MVFR WITH SHRA.

KJB

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

A COLD FRONT WILL SAG SOUTHWARD ACROSS NORTHERN ILLINOIS THROUGH
THE AFTERNOON. THIS WILL LEAD TO A NORTHERLY WIND SHIFT ACROSS THE
TERMINALS BY MID TO LATE THIS AFTERNOON. THE EASTERN TAF SITES
COULD EXPERIENCE A BIT MORE OF A NORTHEASTERLY COMPONENT.
HOWEVER...WIND SPEEDS OVERALL APPEAR THAT THEY MAY REMAIN AT OR
UNDER 10 KT WITH THIS NORTHERLY WIND SHIFT.

SCATTERED SHOWERS ARE ALSO EXPECTED ACROSS THE REGION OVER THE
NEXT SEVERAL HOURS AS THIS FRONT...AND AN UPPER LEVEL DISTURBANCE
MOVES OVER THE AREA. ALTHOUGH THESE SHOWERS WILL BE LIGHT...SOME
LOWER CIGS INTO THE LOWER MVFR RANGE MAY DEVELOP FOR A PERIOD THIS
AFTERNOON.

SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA TONIGHT INTO
TUESDAY. THIS WILL RESULT IN CLEARING SKIES THIS EVENING...AND
LIGHT WINDS INTO TUESDAY. SOME PATCHY FOG IS POSSIBLE
OVERNIGHT...MAINLY TO THE WEST AND SOUTH OF THE MAIN CHICAGO
TERMINALS. A LAKE BREEZE MAY DEVELOP ON TUESDAY AFTERNOON WITH THE
LIGHT WIND PATTERN. HOWEVER...CONFIDENCE ON HOW FAR INLAND THIS
FEATURE WOULD PUSH INLAND IS TOO LOW TO ADD A MENTION IN THE
LATEST 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM TO HIGH CONFIDENCE IN WIND DIRECTION...LOW-MEDIUM THAT WINDS
  WILL GET AS HIGH AS 10 KT LATE THIS AFTERNOON.
* LOW-MEDIUM CONFIDENCE IN SHRA/MVFR TIMING.

KJB

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

TUESDAY NIGHT THROUGH FRIDAY...PRIMARILY VFR.
SATURDAY THROUGH SUNDAY...PERIODIC CHANCES FOR THUNDERSTORMS.

BMD

&&

.MARINE...
246 PM CDT

WEAK LOW PRESSURE WILL PUSH EAST THROUGH THE OHIO VALLEY AND
DISSIPATE THIS EVENING AS HIGH PRESSURE MOVES INTO THE MID
MISSOURI VALLEY TONIGHT. AHEAD OF THE HIGH A WEAK COLD FRONT WILL
SPREAD DOWN THE REMAINDER OF THE LAKE THIS EVENING AND BRIEFLY
INCREASE NORTH WINDS TO NEAR 20 KT THE HIGH WILL WEAKEN AND MOVE
OVER LAKE MICHIGAN ON TUESDAY. LOW PRESSURE OVER HUDSON BAY WILL
SPREAD INTO QUEBEC ON WEDNESDAY AS HIGH PRESSURE PUSHES SOUTH OUT
OF NORTHERN MANITOBA. AHEAD OF THE HIGH THE SOUTHWEST GRADIENT
INCREASES WITH WINDS 15 TO 25 KT FOR THE NORTH HALF OF THE LAKE. THE
HIGH REACHES LAKE SUPERIOR THURSDAY EVENING AND WILL PUSH A COLD
FRONT DOWN THE LAKE THURSDAY NIGHT. THIS HIGH WILL THEN MOVE TO
THE EASTERN LAKES BY LATE THURSDAY INTO FRIDAY AS SEVERAL LOWS
ORGANIZE IN THE CENTRAL PLAINS AND CANADIAN PRAIRIES.

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 151921
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
221 PM CDT MON SEP 15 2014

.DISCUSSION...
221 PM CDT

TONIGHT...
FRONTAL BOUNDARY THIS AFTERNOON CONTINUES TO SLIDE SOUTHEAST ACROSS
THE FORECAST AREA. VISIBLE IMAGERY ALONG AND JUST AHEAD OF THE
BOUNDARY INDICATED SOME VERTICAL GROWTH TO THE CLOUDS...SUGGESTIVE
OF SOME INSTABILITY. THERE HAS BEEN SOME SPOTTY CONVECTION ACROSS
NORTHEAST MO STRETCHING EAST THROUGH IL/CENTRAL IN BUT SOUTH OF THE
CWFA. DESPITE CONSIDERABLE SOLAR SHIELDING HAS BEEN ABLE TO KEEP
TEMPS IN THE 50S...WITH A FEW LOCATIONS BEING ABLE TO NUDGE TO ARND
60. WINDS WILL SHIFT NORTHWEST/NORTH BEHIND THE BOUNDARY WITH MUCH
DRIER/COOLER AIR STEADILY FILTERING INTO THE REGION OVERNIGHT.
PRECIP WILL COME TO AN END LATER THIS AFTN/EARLY EVE...WITH JUST A
FEW LINGERING SHOWERS ALONG AND EAST OF GIBSON CITY TO FOWLER. TEMPS
OVERNIGHT WILL COOL INTO THE LOW/MID 40S...WITH A FEW OF THE
TRADITIONALLY COOL SPOTS POSSIBLY DIPPING INTO THE UPR 30S BEFORE
DAYBREAK TUE. MEANWHILE CLOSER TO DOWNTOWN CHICAGO...THE URBAN HEAT
ISLAND SHUD AID IN KEEPING TEMPS IN THE UPR 40S TO ARND 50. THE ONLY
WILDCARD FOR OVERNIGHT LOWS WILL BE SKY COVER/WINDS...WHICH WITH
HIGH PRESSURE BUILDING IN SHUD ERODE/DIMINISH.

THERE IS ALSO SOME CONCERN THAT WITH THE LACK MIXING THIS AFTN AND
EXPECTED TEMPS BEING COOLER THAN AFTN DEW PTS...COUPLED WITH LIGHT
WINDS...COULD POINT TOWARDS PATCHY FOG DEVELOPING AWAY FROM THE
METRO AREA.

TUESDAY THROUGH THURSDAY...
RATHER BENIGN PATTERN FOR A GOOD PORTION OF THE WEEK. BROAD
ANTI-CYCLONIC FLOW WILL BUILD INTO THE REGION TUESDAY...WITH THE
MID-LVL TROUGH PIVOTING EAST. THE LONGWAVE PATTERN WILL LIKELY KEEP
THE REGION IN A CONTINUED NORTHWEST FLOW AS MID-LVL RIDGING RETURNS
TO THE WESTERN CONUS. GUIDANCE SUGGESTS THE SFC RIDGE THAT ARRIVES
TUE WILL SHIFT EAST...HOWEVER ANOTHER DOME OF HIGH PRESSURE FROM
CANADA IS THEN POISED TO SLIDE SOUTH AND CONTINUE THE DRY/COOL
WEATHER WED/THUR. TEMPS WILL GENERALLY REMAIN IN THE MID/UPR
60S...BUT POSSIBLY REACH 70 DEG IN SEVERAL AREAS FOR THUR. ABUNDANT
SUNSHINE IS EXPECTED EACH OF THE NEXT SEVERAL DAYS AS WELL.
OVERNIGHT LOWS WILL ALSO DIP INTO THE 40S TUE NGT/WED NGT...THEN
WITH THE SFC RIDGE BEGINNING TO PUSH EAST THUR NGT TEMPS COULD HOLD
ARND 50.

CONFIDENCE...HIGH.

FRIDAY THROUGH SUNDAY...
WITH THE SFC RIDGE POISED TO PUSH EAST OF THE REGION FRI...FLOW WILL
BE TURNING SOUTHERLY AND THE MID-LVL WAVE STARTING TO FLATTEN.
ENSEMBLES CONTINUE TO SHOW CONSIDERABLE SPREAD ON TIMING OF
PRECIP/MOISTURE RETURNING...WITH MOST MEMBERS POINTING TOWARDS FRI
NGT. THE ATMOSPHERE WILL MODERATE BY FRI/SAT WITH TEMPS IN THE
MID/UPR 70S...OR MORE SEASONAL. SAT APPEARS TO BE THE MOST FAVORABLE
PERIOD TO SEE SPOTTY SHOWERS/THUNDERSTORMS AS A MID-LVL TROUGH
DEVELOPS OVER THE CENTRAL PLAINS AND NEARS THE REGION SAT AFTN/EVE.
THEN FOR THE SECOND HALF OF THE WEEKEND SFC RIDGING IS PROGGED TO
RETURN TO THE REGION.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* WIND DIRECTION AND SPEEDS ASSOCIATED WITH FROPA THIS AFTERNOON
  ...NORTH-NORTHEAST WIND LOOKING LIKELY BY LATE AFTERNOON...WIND
  SPEEDS COULD REMAIN UNDER 10 KT.
* CIGS LOWERING TO MVFR WITH SHRA.

KJB

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

A COLD FRONT WILL SAG SOUTHWARD ACROSS NORTHERN ILLINOIS THROUGH
THE AFTERNOON. THIS WILL LEAD TO A NORTHERLY WIND SHIFT ACROSS THE
TERMINALS BY MID TO LATE THIS AFTERNOON. THE EASTERN TAF SITES
COULD EXPERIENCE A BIT MORE OF A NORTHEASTERLY COMPONENT.
HOWEVER...WIND SPEEDS OVERALL APPEAR THAT THEY MAY REMAIN AT OR
UNDER 10 KT WITH THIS NORTHERLY WIND SHIFT.

SCATTERED SHOWERS ARE ALSO EXPECTED ACROSS THE REGION OVER THE
NEXT SEVERAL HOURS AS THIS FRONT...AND AN UPPER LEVEL DISTURBANCE
MOVES OVER THE AREA. ALTHOUGH THESE SHOWERS WILL BE LIGHT...SOME
LOWER CIGS INTO THE LOWER MVFR RANGE MAY DEVELOP FOR A PERIOD THIS
AFTERNOON.

SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA TONIGHT INTO
TUESDAY. THIS WILL RESULT IN CLEARING SKIES THIS EVENING...AND
LIGHT WINDS INTO TUESDAY. SOME PATCHY FOG IS POSSIBLE
OVERNIGHT...MAINLY TO THE WEST AND SOUTH OF THE MAIN CHICAGO
TERMINALS. A LAKE BREEZE MAY DEVELOP ON TUESDAY AFTERNOON WITH THE
LIGHT WIND PATTERN. HOWEVER...CONFIDENCE ON HOW FAR INLAND THIS
FEATURE WOULD PUSH INLAND IS TOO LOW TO ADD A MENTION IN THE
LATEST 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM TO HIGH CONFIDENCE IN WIND DIRECTION...LOW-MEDIUM THAT WINDS
  WILL GET AS HIGH AS 10 KT LATE THIS AFTERNOON.
* LOW-MEDIUM CONFIDENCE IN SHRA/MVFR TIMING.

KJB

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

TUESDAY NIGHT THROUGH FRIDAY...PRIMARILY VFR.
SATURDAY THROUGH SUNDAY...PERIODIC CHANCES FOR THUNDERSTORMS.

BMD

&&

.MARINE...
303 AM CDT

LOW PRESSURE NEAR JAMES BAY THIS MORNING WILL DRAG A COLD FRONT
ACROSS LAKE MICHIGAN. WINDS WILL TURN NORTHWEST TO NORTH BEHIND THE
FRONT...AND MAY BRIEFLY INCREASE INTO THE 20 TO 25 KT RANGE
ESPECIALLY ON THE SOUTH END OF THE LAKE THIS EVENING. HIGH PRESSURE
WILL BUILD IN BEHIND THE FRONT ALLOWING WINDS TO REMAIN MODEST FOR A
PERIOD BEFORE SOUTHWEST FLOW BEGINS TO FRESHEN UP AGAIN OVER THE
NORTH HALF OF LAKE MICHIGAN MIDDAY TUESDAY. ANOTHER COLD FRONT WILL
DIVE SOUTH ACROSS LAKE MICHIGAN ON WEDNESDAY TURNING WINDS NORTH TO
NORTHEAST AND INCREASING FOR A SHORT PERIOD TO AROUND 30 KT ONCE
AGAIN.

BMD

&&

.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 151921
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
221 PM CDT MON SEP 15 2014

.DISCUSSION...
221 PM CDT

TONIGHT...
FRONTAL BOUNDARY THIS AFTERNOON CONTINUES TO SLIDE SOUTHEAST ACROSS
THE FORECAST AREA. VISIBLE IMAGERY ALONG AND JUST AHEAD OF THE
BOUNDARY INDICATED SOME VERTICAL GROWTH TO THE CLOUDS...SUGGESTIVE
OF SOME INSTABILITY. THERE HAS BEEN SOME SPOTTY CONVECTION ACROSS
NORTHEAST MO STRETCHING EAST THROUGH IL/CENTRAL IN BUT SOUTH OF THE
CWFA. DESPITE CONSIDERABLE SOLAR SHIELDING HAS BEEN ABLE TO KEEP
TEMPS IN THE 50S...WITH A FEW LOCATIONS BEING ABLE TO NUDGE TO ARND
60. WINDS WILL SHIFT NORTHWEST/NORTH BEHIND THE BOUNDARY WITH MUCH
DRIER/COOLER AIR STEADILY FILTERING INTO THE REGION OVERNIGHT.
PRECIP WILL COME TO AN END LATER THIS AFTN/EARLY EVE...WITH JUST A
FEW LINGERING SHOWERS ALONG AND EAST OF GIBSON CITY TO FOWLER. TEMPS
OVERNIGHT WILL COOL INTO THE LOW/MID 40S...WITH A FEW OF THE
TRADITIONALLY COOL SPOTS POSSIBLY DIPPING INTO THE UPR 30S BEFORE
DAYBREAK TUE. MEANWHILE CLOSER TO DOWNTOWN CHICAGO...THE URBAN HEAT
ISLAND SHUD AID IN KEEPING TEMPS IN THE UPR 40S TO ARND 50. THE ONLY
WILDCARD FOR OVERNIGHT LOWS WILL BE SKY COVER/WINDS...WHICH WITH
HIGH PRESSURE BUILDING IN SHUD ERODE/DIMINISH.

THERE IS ALSO SOME CONCERN THAT WITH THE LACK MIXING THIS AFTN AND
EXPECTED TEMPS BEING COOLER THAN AFTN DEW PTS...COUPLED WITH LIGHT
WINDS...COULD POINT TOWARDS PATCHY FOG DEVELOPING AWAY FROM THE
METRO AREA.

TUESDAY THROUGH THURSDAY...
RATHER BENIGN PATTERN FOR A GOOD PORTION OF THE WEEK. BROAD
ANTI-CYCLONIC FLOW WILL BUILD INTO THE REGION TUESDAY...WITH THE
MID-LVL TROUGH PIVOTING EAST. THE LONGWAVE PATTERN WILL LIKELY KEEP
THE REGION IN A CONTINUED NORTHWEST FLOW AS MID-LVL RIDGING RETURNS
TO THE WESTERN CONUS. GUIDANCE SUGGESTS THE SFC RIDGE THAT ARRIVES
TUE WILL SHIFT EAST...HOWEVER ANOTHER DOME OF HIGH PRESSURE FROM
CANADA IS THEN POISED TO SLIDE SOUTH AND CONTINUE THE DRY/COOL
WEATHER WED/THUR. TEMPS WILL GENERALLY REMAIN IN THE MID/UPR
60S...BUT POSSIBLY REACH 70 DEG IN SEVERAL AREAS FOR THUR. ABUNDANT
SUNSHINE IS EXPECTED EACH OF THE NEXT SEVERAL DAYS AS WELL.
OVERNIGHT LOWS WILL ALSO DIP INTO THE 40S TUE NGT/WED NGT...THEN
WITH THE SFC RIDGE BEGINNING TO PUSH EAST THUR NGT TEMPS COULD HOLD
ARND 50.

CONFIDENCE...HIGH.

FRIDAY THROUGH SUNDAY...
WITH THE SFC RIDGE POISED TO PUSH EAST OF THE REGION FRI...FLOW WILL
BE TURNING SOUTHERLY AND THE MID-LVL WAVE STARTING TO FLATTEN.
ENSEMBLES CONTINUE TO SHOW CONSIDERABLE SPREAD ON TIMING OF
PRECIP/MOISTURE RETURNING...WITH MOST MEMBERS POINTING TOWARDS FRI
NGT. THE ATMOSPHERE WILL MODERATE BY FRI/SAT WITH TEMPS IN THE
MID/UPR 70S...OR MORE SEASONAL. SAT APPEARS TO BE THE MOST FAVORABLE
PERIOD TO SEE SPOTTY SHOWERS/THUNDERSTORMS AS A MID-LVL TROUGH
DEVELOPS OVER THE CENTRAL PLAINS AND NEARS THE REGION SAT AFTN/EVE.
THEN FOR THE SECOND HALF OF THE WEEKEND SFC RIDGING IS PROGGED TO
RETURN TO THE REGION.

CONFIDENCE...MEDIUM/HIGH.

BEACHLER

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* WIND DIRECTION AND SPEEDS ASSOCIATED WITH FROPA THIS AFTERNOON
  ...NORTH-NORTHEAST WIND LOOKING LIKELY BY LATE AFTERNOON...WIND
  SPEEDS COULD REMAIN UNDER 10 KT.
* CIGS LOWERING TO MVFR WITH SHRA.

KJB

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

A COLD FRONT WILL SAG SOUTHWARD ACROSS NORTHERN ILLINOIS THROUGH
THE AFTERNOON. THIS WILL LEAD TO A NORTHERLY WIND SHIFT ACROSS THE
TERMINALS BY MID TO LATE THIS AFTERNOON. THE EASTERN TAF SITES
COULD EXPERIENCE A BIT MORE OF A NORTHEASTERLY COMPONENT.
HOWEVER...WIND SPEEDS OVERALL APPEAR THAT THEY MAY REMAIN AT OR
UNDER 10 KT WITH THIS NORTHERLY WIND SHIFT.

SCATTERED SHOWERS ARE ALSO EXPECTED ACROSS THE REGION OVER THE
NEXT SEVERAL HOURS AS THIS FRONT...AND AN UPPER LEVEL DISTURBANCE
MOVES OVER THE AREA. ALTHOUGH THESE SHOWERS WILL BE LIGHT...SOME
LOWER CIGS INTO THE LOWER MVFR RANGE MAY DEVELOP FOR A PERIOD THIS
AFTERNOON.

SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA TONIGHT INTO
TUESDAY. THIS WILL RESULT IN CLEARING SKIES THIS EVENING...AND
LIGHT WINDS INTO TUESDAY. SOME PATCHY FOG IS POSSIBLE
OVERNIGHT...MAINLY TO THE WEST AND SOUTH OF THE MAIN CHICAGO
TERMINALS. A LAKE BREEZE MAY DEVELOP ON TUESDAY AFTERNOON WITH THE
LIGHT WIND PATTERN. HOWEVER...CONFIDENCE ON HOW FAR INLAND THIS
FEATURE WOULD PUSH INLAND IS TOO LOW TO ADD A MENTION IN THE
LATEST 30 HOUR ORD TAF.

KJB

//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM TO HIGH CONFIDENCE IN WIND DIRECTION...LOW-MEDIUM THAT WINDS
  WILL GET AS HIGH AS 10 KT LATE THIS AFTERNOON.
* LOW-MEDIUM CONFIDENCE IN SHRA/MVFR TIMING.

KJB

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

TUESDAY NIGHT THROUGH FRIDAY...PRIMARILY VFR.
SATURDAY THROUGH SUNDAY...PERIODIC CHANCES FOR THUNDERSTORMS.

BMD

&&

.MARINE...
303 AM CDT

LOW PRESSURE NEAR JAMES BAY THIS MORNING WILL DRAG A COLD FRONT
ACROSS LAKE MICHIGAN. WINDS WILL TURN NORTHWEST TO NORTH BEHIND THE
FRONT...AND MAY BRIEFLY INCREASE INTO THE 20 TO 25 KT RANGE
ESPECIALLY ON THE SOUTH END OF THE LAKE THIS EVENING. HIGH PRESSURE
WILL BUILD IN BEHIND THE FRONT ALLOWING WINDS TO REMAIN MODEST FOR A
PERIOD BEFORE SOUTHWEST FLOW BEGINS TO FRESHEN UP AGAIN OVER THE
NORTH HALF OF LAKE MICHIGAN MIDDAY TUESDAY. ANOTHER COLD FRONT WILL
DIVE SOUTH ACROSS LAKE MICHIGAN ON WEDNESDAY TURNING WINDS NORTH TO
NORTHEAST AND INCREASING FOR A SHORT PERIOD TO AROUND 30 KT ONCE
AGAIN.

BMD

&&

.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 151756
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1256 PM CDT Mon Sep 15 2014

.UPDATE...
ISSUED AT 1135 AM CDT MON SEP 15 2014

Minor adjustments to the forecast as showers and thunderstorms
move through Central Illinois ahead of an advancing cold front.
Though severe weather is not anticipated, locally heavy rain and
frequent lightning will accompany the storms this morning.
Temperatures across the northern portions of the CWA will struggle
into the lower 60s, with warmer temps along and south of I-70. No
major updates anticipated at this time.

&&

.SHORT TERM...(Today)
ISSUED AT 301 AM CDT MON SEP 15 2014

Main concern for today is shower/storm timing/chances associated
with the passage of a weak cold front and driving upper level
energy. The upper level forcing is somewhat complicated as it will
be provided by two separate disturbances. The first/weaker wave is
tracking east across the central Plains, while the second/stronger
wave is diving across the northern Plains. The second wave should
end up being the dominant feature for us, although both waves should
tend to shear out to some degree as they push into the confluent
flow across the Midwest.

The best forcing/frontal arrival have slowed some from previous
forecast, with the front not expected to clear the entire forecast
area until this evening. This slower arrival will also delay the
better chances for precipitation until the midday/afternoon hours.
Have expanded thunder mention to the entire forecast area today
given the steep mid-level lapse rates on forecast soundings
area wide. This north/east shift of thunder chances is also supported
by storms currently tracking east across southern Iowa. These storms
were located on the nose of a 25kt low-level jet in advance of the
central Plains wave. The forcing of the LLJ and central Plains wave
should weaken before reaching the local area, however it is expected
to be replaced by upper-level divergence/mid-level frontogenesis as
a jet streak ahead of the northern Plains wave arrives. A fairly
wide N-S temperature range is likely across the forecast area today
considering the fairly early arrival of the front/precipitation in
our northwest counties, compared to the evening frontal arrival
across southeast Illinois.

&&

.LONG TERM...(Tonight through Sunday)
ISSUED AT 301 AM CDT MON SEP 15 2014

Cold front should reach the I-70 corridor by sunset and be out of
the forecast area shortly afterward, taking the rain with it. Fairly
sharp clearing expected behind the front as high pressure builds in,
but clouds will linger much of the night in southeast Illinois.

Quiet midweek period expected as the high drifts across the Midwest.
Evening models have various interpretations of some convective
activity to our southwest on Wednesday, along the periphery of some
upper ridging across the Rockies. but all models keep it in Missouri
and will thus keep our forecast dry. Slow moderating trend in
temperatures with lower 70s widespread by Thursday.

Upper ridge breaks down late in the week before rebuilding along the
West Coast late in the weekend. Longer range models dig a sharpening
upper wave across the mid and upper Mississippi Valley by Saturday
night, with rain chances mainly focused in the Saturday afternoon
and evening time frame. Beyond that, the models show quite a bit of
divergence in the evolution of this wave. The latest ECMWF model
forms a closed low over Lake Superior Saturday night and drives a
large slug of cooler air across the Midwest later in the weekend,
while the steadier GFS is much more progressive and shows much less
of a temperature change. That sharper scenario is more of a recent
development and thus for now have only shown some small decrease in
temperatures for Sunday and Monday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 1245 PM CDT MON SEP 15 2014

Mostly IFR at terminals this afternoon. Conditions improving to
MVFR later this evening and through the night. Scattering out the
low clouds per time heights in both the GFS and the NAM as well as
HRRR.  At time of issuance, PIA cigs at 500 ft were isolated.
However, in the wake of the showers, GBG and C75 have both
dropped, which is in line with a progression of the IFR line
behind the showers. Concern that the IFR cigs will remain after
20z- 22z at the end of the tempos up to potentially 00z and will
likely be amending. Models clearing out the skies quicker will
assist in the potential for fog in the morning hours. Started the
trend, but conservative for now. VWP lighting up a LLWS issue with
some SW winds just off the deck at 35kts. Somewhat isolated, but
will amend accordingly.

&&

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

$$

UPDATE...HJS
SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...HJS






000
FXUS63 KILX 151756
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1256 PM CDT Mon Sep 15 2014

.UPDATE...
ISSUED AT 1135 AM CDT MON SEP 15 2014

Minor adjustments to the forecast as showers and thunderstorms
move through Central Illinois ahead of an advancing cold front.
Though severe weather is not anticipated, locally heavy rain and
frequent lightning will accompany the storms this morning.
Temperatures across the northern portions of the CWA will struggle
into the lower 60s, with warmer temps along and south of I-70. No
major updates anticipated at this time.

&&

.SHORT TERM...(Today)
ISSUED AT 301 AM CDT MON SEP 15 2014

Main concern for today is shower/storm timing/chances associated
with the passage of a weak cold front and driving upper level
energy. The upper level forcing is somewhat complicated as it will
be provided by two separate disturbances. The first/weaker wave is
tracking east across the central Plains, while the second/stronger
wave is diving across the northern Plains. The second wave should
end up being the dominant feature for us, although both waves should
tend to shear out to some degree as they push into the confluent
flow across the Midwest.

The best forcing/frontal arrival have slowed some from previous
forecast, with the front not expected to clear the entire forecast
area until this evening. This slower arrival will also delay the
better chances for precipitation until the midday/afternoon hours.
Have expanded thunder mention to the entire forecast area today
given the steep mid-level lapse rates on forecast soundings
area wide. This north/east shift of thunder chances is also supported
by storms currently tracking east across southern Iowa. These storms
were located on the nose of a 25kt low-level jet in advance of the
central Plains wave. The forcing of the LLJ and central Plains wave
should weaken before reaching the local area, however it is expected
to be replaced by upper-level divergence/mid-level frontogenesis as
a jet streak ahead of the northern Plains wave arrives. A fairly
wide N-S temperature range is likely across the forecast area today
considering the fairly early arrival of the front/precipitation in
our northwest counties, compared to the evening frontal arrival
across southeast Illinois.

&&

.LONG TERM...(Tonight through Sunday)
ISSUED AT 301 AM CDT MON SEP 15 2014

Cold front should reach the I-70 corridor by sunset and be out of
the forecast area shortly afterward, taking the rain with it. Fairly
sharp clearing expected behind the front as high pressure builds in,
but clouds will linger much of the night in southeast Illinois.

Quiet midweek period expected as the high drifts across the Midwest.
Evening models have various interpretations of some convective
activity to our southwest on Wednesday, along the periphery of some
upper ridging across the Rockies. but all models keep it in Missouri
and will thus keep our forecast dry. Slow moderating trend in
temperatures with lower 70s widespread by Thursday.

Upper ridge breaks down late in the week before rebuilding along the
West Coast late in the weekend. Longer range models dig a sharpening
upper wave across the mid and upper Mississippi Valley by Saturday
night, with rain chances mainly focused in the Saturday afternoon
and evening time frame. Beyond that, the models show quite a bit of
divergence in the evolution of this wave. The latest ECMWF model
forms a closed low over Lake Superior Saturday night and drives a
large slug of cooler air across the Midwest later in the weekend,
while the steadier GFS is much more progressive and shows much less
of a temperature change. That sharper scenario is more of a recent
development and thus for now have only shown some small decrease in
temperatures for Sunday and Monday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 1245 PM CDT MON SEP 15 2014

Mostly IFR at terminals this afternoon. Conditions improving to
MVFR later this evening and through the night. Scattering out the
low clouds per time heights in both the GFS and the NAM as well as
HRRR.  At time of issuance, PIA cigs at 500 ft were isolated.
However, in the wake of the showers, GBG and C75 have both
dropped, which is in line with a progression of the IFR line
behind the showers. Concern that the IFR cigs will remain after
20z- 22z at the end of the tempos up to potentially 00z and will
likely be amending. Models clearing out the skies quicker will
assist in the potential for fog in the morning hours. Started the
trend, but conservative for now. VWP lighting up a LLWS issue with
some SW winds just off the deck at 35kts. Somewhat isolated, but
will amend accordingly.

&&

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

$$

UPDATE...HJS
SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...HJS






000
FXUS63 KILX 151756
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1256 PM CDT Mon Sep 15 2014

.UPDATE...
ISSUED AT 1135 AM CDT MON SEP 15 2014

Minor adjustments to the forecast as showers and thunderstorms
move through Central Illinois ahead of an advancing cold front.
Though severe weather is not anticipated, locally heavy rain and
frequent lightning will accompany the storms this morning.
Temperatures across the northern portions of the CWA will struggle
into the lower 60s, with warmer temps along and south of I-70. No
major updates anticipated at this time.

&&

.SHORT TERM...(Today)
ISSUED AT 301 AM CDT MON SEP 15 2014

Main concern for today is shower/storm timing/chances associated
with the passage of a weak cold front and driving upper level
energy. The upper level forcing is somewhat complicated as it will
be provided by two separate disturbances. The first/weaker wave is
tracking east across the central Plains, while the second/stronger
wave is diving across the northern Plains. The second wave should
end up being the dominant feature for us, although both waves should
tend to shear out to some degree as they push into the confluent
flow across the Midwest.

The best forcing/frontal arrival have slowed some from previous
forecast, with the front not expected to clear the entire forecast
area until this evening. This slower arrival will also delay the
better chances for precipitation until the midday/afternoon hours.
Have expanded thunder mention to the entire forecast area today
given the steep mid-level lapse rates on forecast soundings
area wide. This north/east shift of thunder chances is also supported
by storms currently tracking east across southern Iowa. These storms
were located on the nose of a 25kt low-level jet in advance of the
central Plains wave. The forcing of the LLJ and central Plains wave
should weaken before reaching the local area, however it is expected
to be replaced by upper-level divergence/mid-level frontogenesis as
a jet streak ahead of the northern Plains wave arrives. A fairly
wide N-S temperature range is likely across the forecast area today
considering the fairly early arrival of the front/precipitation in
our northwest counties, compared to the evening frontal arrival
across southeast Illinois.

&&

.LONG TERM...(Tonight through Sunday)
ISSUED AT 301 AM CDT MON SEP 15 2014

Cold front should reach the I-70 corridor by sunset and be out of
the forecast area shortly afterward, taking the rain with it. Fairly
sharp clearing expected behind the front as high pressure builds in,
but clouds will linger much of the night in southeast Illinois.

Quiet midweek period expected as the high drifts across the Midwest.
Evening models have various interpretations of some convective
activity to our southwest on Wednesday, along the periphery of some
upper ridging across the Rockies. but all models keep it in Missouri
and will thus keep our forecast dry. Slow moderating trend in
temperatures with lower 70s widespread by Thursday.

Upper ridge breaks down late in the week before rebuilding along the
West Coast late in the weekend. Longer range models dig a sharpening
upper wave across the mid and upper Mississippi Valley by Saturday
night, with rain chances mainly focused in the Saturday afternoon
and evening time frame. Beyond that, the models show quite a bit of
divergence in the evolution of this wave. The latest ECMWF model
forms a closed low over Lake Superior Saturday night and drives a
large slug of cooler air across the Midwest later in the weekend,
while the steadier GFS is much more progressive and shows much less
of a temperature change. That sharper scenario is more of a recent
development and thus for now have only shown some small decrease in
temperatures for Sunday and Monday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 1245 PM CDT MON SEP 15 2014

Mostly IFR at terminals this afternoon. Conditions improving to
MVFR later this evening and through the night. Scattering out the
low clouds per time heights in both the GFS and the NAM as well as
HRRR.  At time of issuance, PIA cigs at 500 ft were isolated.
However, in the wake of the showers, GBG and C75 have both
dropped, which is in line with a progression of the IFR line
behind the showers. Concern that the IFR cigs will remain after
20z- 22z at the end of the tempos up to potentially 00z and will
likely be amending. Models clearing out the skies quicker will
assist in the potential for fog in the morning hours. Started the
trend, but conservative for now. VWP lighting up a LLWS issue with
some SW winds just off the deck at 35kts. Somewhat isolated, but
will amend accordingly.

&&

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

$$

UPDATE...HJS
SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...HJS






000
FXUS63 KILX 151756
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1256 PM CDT Mon Sep 15 2014

.UPDATE...
ISSUED AT 1135 AM CDT MON SEP 15 2014

Minor adjustments to the forecast as showers and thunderstorms
move through Central Illinois ahead of an advancing cold front.
Though severe weather is not anticipated, locally heavy rain and
frequent lightning will accompany the storms this morning.
Temperatures across the northern portions of the CWA will struggle
into the lower 60s, with warmer temps along and south of I-70. No
major updates anticipated at this time.

&&

.SHORT TERM...(Today)
ISSUED AT 301 AM CDT MON SEP 15 2014

Main concern for today is shower/storm timing/chances associated
with the passage of a weak cold front and driving upper level
energy. The upper level forcing is somewhat complicated as it will
be provided by two separate disturbances. The first/weaker wave is
tracking east across the central Plains, while the second/stronger
wave is diving across the northern Plains. The second wave should
end up being the dominant feature for us, although both waves should
tend to shear out to some degree as they push into the confluent
flow across the Midwest.

The best forcing/frontal arrival have slowed some from previous
forecast, with the front not expected to clear the entire forecast
area until this evening. This slower arrival will also delay the
better chances for precipitation until the midday/afternoon hours.
Have expanded thunder mention to the entire forecast area today
given the steep mid-level lapse rates on forecast soundings
area wide. This north/east shift of thunder chances is also supported
by storms currently tracking east across southern Iowa. These storms
were located on the nose of a 25kt low-level jet in advance of the
central Plains wave. The forcing of the LLJ and central Plains wave
should weaken before reaching the local area, however it is expected
to be replaced by upper-level divergence/mid-level frontogenesis as
a jet streak ahead of the northern Plains wave arrives. A fairly
wide N-S temperature range is likely across the forecast area today
considering the fairly early arrival of the front/precipitation in
our northwest counties, compared to the evening frontal arrival
across southeast Illinois.

&&

.LONG TERM...(Tonight through Sunday)
ISSUED AT 301 AM CDT MON SEP 15 2014

Cold front should reach the I-70 corridor by sunset and be out of
the forecast area shortly afterward, taking the rain with it. Fairly
sharp clearing expected behind the front as high pressure builds in,
but clouds will linger much of the night in southeast Illinois.

Quiet midweek period expected as the high drifts across the Midwest.
Evening models have various interpretations of some convective
activity to our southwest on Wednesday, along the periphery of some
upper ridging across the Rockies. but all models keep it in Missouri
and will thus keep our forecast dry. Slow moderating trend in
temperatures with lower 70s widespread by Thursday.

Upper ridge breaks down late in the week before rebuilding along the
West Coast late in the weekend. Longer range models dig a sharpening
upper wave across the mid and upper Mississippi Valley by Saturday
night, with rain chances mainly focused in the Saturday afternoon
and evening time frame. Beyond that, the models show quite a bit of
divergence in the evolution of this wave. The latest ECMWF model
forms a closed low over Lake Superior Saturday night and drives a
large slug of cooler air across the Midwest later in the weekend,
while the steadier GFS is much more progressive and shows much less
of a temperature change. That sharper scenario is more of a recent
development and thus for now have only shown some small decrease in
temperatures for Sunday and Monday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 1245 PM CDT MON SEP 15 2014

Mostly IFR at terminals this afternoon. Conditions improving to
MVFR later this evening and through the night. Scattering out the
low clouds per time heights in both the GFS and the NAM as well as
HRRR.  At time of issuance, PIA cigs at 500 ft were isolated.
However, in the wake of the showers, GBG and C75 have both
dropped, which is in line with a progression of the IFR line
behind the showers. Concern that the IFR cigs will remain after
20z- 22z at the end of the tempos up to potentially 00z and will
likely be amending. Models clearing out the skies quicker will
assist in the potential for fog in the morning hours. Started the
trend, but conservative for now. VWP lighting up a LLWS issue with
some SW winds just off the deck at 35kts. Somewhat isolated, but
will amend accordingly.

&&

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

$$

UPDATE...HJS
SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...HJS






000
FXUS63 KLOT 151708
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1208 PM CDT MON SEP 15 2014

.DISCUSSION...
311 AM CDT

DISMAL AND SHOWERY WEATHER ON TAP TODAY FOLLOWED BY PRETTY
SPECTACULAR WEATHER THE REMAINDER OF THE WEEK.

FAIRLY ENERGETIC SHORTWAVE TROUGH OVER THE DAKOTAS THIS MORNING
WILL DIG SOUTHEASTWARD INTO THE LOWER LAKES LATER TODAY BEFORE
SHIFTING EAST OF THE REGION TONIGHT. LOW-MID LEVEL FRONTOGENESIS IN
THE RIGHT ENTRANCE REGION OF 100KT+ 250MB JET IS ALREADY SUPPORTING
A BAND OF RAIN FROM EASTERN SD EAST INTO CENTRAL WISCONSIN. IN
ADDITION...SECOND AREA OF SHOWERS AND THUNDERSTORMS DEVELOPING OVER
IOWA IN ASSOCIATED WITH STRENGTHENING LOW LEVEL JET/WAA. THESE TWO
REGIONS OF PRECIP ARE LIKELY TO CONGEAL AND SPREAD ACROSS OUR CWA
LATER THIS MORNING AND CONTINUE INTO THE AFTERNOON. SOME WEAK
ELEVATED INSTABILITY COULD SUPPORT AN ISOLATED THUNDERSTORM SOUTH
BUT CHANCES AND AREAL COVERAGE OF THUNDER APPEAR LOW. AS TROUGH AXIS
TRANSLATE QUICKLY EASTWARD LOOK FOR RAIN/SHOWERS TO END...POSSIBLY
AS A PERIOD OF DRIZZLE LATER THIS AFTERNOON. TEMPS ARE TRICKY AND
WILL HINGE ON HOW MUCH THEY CAN RISE BEFORE RAIN STARTS AND THEY
LOSE A LITTLE GROUND THIS AFTERNOON.

STRONG SUBSIDENCE AND DRYING ARE FORECAST IN THE WAKE OF THE TROUGH
WHICH SHOULD LEAD TO RAPID CLEARING THIS EVENING WITH ANOTHER FAIRLY
HEALTHY PUSH OF EARLY SEASON COLD AIR ARRIVING TONIGHT. ONCE AGAIN
LOOKING FOR LOWS TO DROP INTO THE 30S OVER WESTERN PORTIONS OF THE
CWA...PARTICULARLY THE TYPICALLY FAVORED COOL SPOTS. CANT RULE OUT A
TOUCH OF FROST IN THE SHELTERED COOL SPOTS...ESPECIALLY ON ELEVATED
OBJECTS...BUT NOT EXPECTED TO BE A BIG ENOUGH DEAL TO INCLUDE IN
GRIDS.

TUESDAY LOOKS TO BE SUNNY AND UNSEASONABLY COOL...BUT NOT AS CHILLY
AS LAST WEEK. A SLOW BUT STEADY WARMING TREND WILL COMMENCE
WEDNESDAY AND CONTINUE INTO THE WEEKEND WITH HIGHS EVENTUALLY
REBOUNDING BACK TOWARD IF NOT A BIT ABOVE AVERAGE TOWARD THE
WEEKEND. NO RAIN IS EXPECTED THROUGH FRIDAY WITH PLENTY OF SUNSHINE
AND ALL AROUND PLEASANT WEATHER. MEDIUM RANGE MODELS DO SUGGEST
PATTERN COULD TURN POTENTIALLY STORMIER NEXT WEEKEND AS FLOW
FLATTENS OUT A BIT AND WARM AIR ADVECTION STRENGTHENS IN ADVANCE OF
TROUGH DIGGING INTO THE NORTHERN/CENTRAL PLAINS. STILL SOME
DISAGREEMENT IN THE DETAILS...NOT SURPRISINGLY THIS FAR OUT...SO
KEPT POPS MODEST FOR NOW UNTIL DETAILS CAN BE BETTER PINNED DOWN IN
THE COMING DAYS.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* WIND DIRECTION AND SPEEDS ASSOCIATED WITH FROPA THIS AFTERNOON
  ...NORTH-NORTHEAST WIND LOOKING LIKELY BY LATE AFTERNOON...WIND
  SPEEDS COULD REMAIN UNDER 10 KT.
* CIGS LOWERING TO MVFR WITH SHRA.

KJB

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

A COLD FRONT WILL SAG SOUTHWARD ACROSS NORTHERN ILLINOIS THROUGH
THE AFTERNOON. THIS WILL LEAD TO A NORTHERLY WIND SHIFT ACROSS THE
TERMINALS BY MID TO LATE THIS AFTERNOON. THE EASTERN TAF SITES
COULD EXPERIENCE A BIT MORE OF A NORTHEASTERLY COMPONENT.
HOWEVER...WIND SPEEDS OVERALL APPEAR THAT THEY MAY REMAIN AT OR
UNDER 10 KT WITH THIS NORTHERLY WIND SHIFT.

SCATTERED SHOWERS ARE ALSO EXPECTED ACROSS THE REGION OVER THE
NEXT SEVERAL HOURS AS THIS FRONT...AND AN UPPER LEVEL DISTURBANCE
MOVES OVER THE AREA. ALTHOUGH THESE SHOWERS WILL BE LIGHT...SOME
LOWER CIGS INTO THE LOWER MVFR RANGE MAY DEVELOP FOR A PERIOD THIS
AFTERNOON.

SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA TONIGHT INTO
TUESDAY. THIS WILL RESULT IN CLEARING SKIES THIS EVENING...AND
LIGHT WINDS INTO TUESDAY. SOME PATCHY FOG IS POSSIBLE
OVERNIGHT...MAINLY TO THE WEST AND SOUTH OF THE MAIN CHICAGO
TERMINALS. A LAKE BREEZE MAY DEVELOP ON TUESDAY AFTERNOON WITH THE
LIGHT WIND PATTERN. HOWEVER...CONFIDENCE ON HOW FAR INLAND THIS
FEATURE WOULD PUSH INLAND IS TOO LOW TO ADD A MENTION IN THE
LATEST 30 HOUR ORD TAF.

KJB


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM TO HIGH CONFIDENCE IN WIND DIRECTION...LOW-MEDIUM THAT WINDS
  WILL GET AS HIGH AS 10 KT LATE THIS AFTERNOON.
* LOW-MEDIUM CONFIDENCE IN SHRA/MVFR TIMING.

KJB

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

TUESDAY NIGHT THROUGH FRIDAY...PRIMARILY VFR.
SATURDAY THROUGH SUNDAY...PERIODIC CHANCES FOR THUNDERSTORMS.

BMD

&&

.MARINE...
303 AM CDT

LOW PRESSURE NEAR JAMES BAY THIS MORNING WILL DRAG A COLD FRONT
ACROSS LAKE MICHIGAN. WINDS WILL TURN NORTHWEST TO NORTH BEHIND THE
FRONT...AND MAY BRIEFLY INCREASE INTO THE 20 TO 25 KT RANGE
ESPECIALLY ON THE SOUTH END OF THE LAKE THIS EVENING. HIGH PRESSURE
WILL BUILD IN BEHIND THE FRONT ALLOWING WINDS TO REMAIN MODEST FOR A
PERIOD BEFORE SOUTHWEST FLOW BEGINS TO FRESHEN UP AGAIN OVER THE
NORTH HALF OF LAKE MICHIGAN MIDDAY TUESDAY. ANOTHER COLD FRONT WILL
DIVE SOUTH ACROSS LAKE MICHIGAN ON WEDNESDAY TURNING WINDS NORTH TO
NORTHEAST AND INCREASING FOR A SHORT PERIOD TO AROUND 30 KT ONCE
AGAIN.

BMD

&&

.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 151708
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1208 PM CDT MON SEP 15 2014

.DISCUSSION...
311 AM CDT

DISMAL AND SHOWERY WEATHER ON TAP TODAY FOLLOWED BY PRETTY
SPECTACULAR WEATHER THE REMAINDER OF THE WEEK.

FAIRLY ENERGETIC SHORTWAVE TROUGH OVER THE DAKOTAS THIS MORNING
WILL DIG SOUTHEASTWARD INTO THE LOWER LAKES LATER TODAY BEFORE
SHIFTING EAST OF THE REGION TONIGHT. LOW-MID LEVEL FRONTOGENESIS IN
THE RIGHT ENTRANCE REGION OF 100KT+ 250MB JET IS ALREADY SUPPORTING
A BAND OF RAIN FROM EASTERN SD EAST INTO CENTRAL WISCONSIN. IN
ADDITION...SECOND AREA OF SHOWERS AND THUNDERSTORMS DEVELOPING OVER
IOWA IN ASSOCIATED WITH STRENGTHENING LOW LEVEL JET/WAA. THESE TWO
REGIONS OF PRECIP ARE LIKELY TO CONGEAL AND SPREAD ACROSS OUR CWA
LATER THIS MORNING AND CONTINUE INTO THE AFTERNOON. SOME WEAK
ELEVATED INSTABILITY COULD SUPPORT AN ISOLATED THUNDERSTORM SOUTH
BUT CHANCES AND AREAL COVERAGE OF THUNDER APPEAR LOW. AS TROUGH AXIS
TRANSLATE QUICKLY EASTWARD LOOK FOR RAIN/SHOWERS TO END...POSSIBLY
AS A PERIOD OF DRIZZLE LATER THIS AFTERNOON. TEMPS ARE TRICKY AND
WILL HINGE ON HOW MUCH THEY CAN RISE BEFORE RAIN STARTS AND THEY
LOSE A LITTLE GROUND THIS AFTERNOON.

STRONG SUBSIDENCE AND DRYING ARE FORECAST IN THE WAKE OF THE TROUGH
WHICH SHOULD LEAD TO RAPID CLEARING THIS EVENING WITH ANOTHER FAIRLY
HEALTHY PUSH OF EARLY SEASON COLD AIR ARRIVING TONIGHT. ONCE AGAIN
LOOKING FOR LOWS TO DROP INTO THE 30S OVER WESTERN PORTIONS OF THE
CWA...PARTICULARLY THE TYPICALLY FAVORED COOL SPOTS. CANT RULE OUT A
TOUCH OF FROST IN THE SHELTERED COOL SPOTS...ESPECIALLY ON ELEVATED
OBJECTS...BUT NOT EXPECTED TO BE A BIG ENOUGH DEAL TO INCLUDE IN
GRIDS.

TUESDAY LOOKS TO BE SUNNY AND UNSEASONABLY COOL...BUT NOT AS CHILLY
AS LAST WEEK. A SLOW BUT STEADY WARMING TREND WILL COMMENCE
WEDNESDAY AND CONTINUE INTO THE WEEKEND WITH HIGHS EVENTUALLY
REBOUNDING BACK TOWARD IF NOT A BIT ABOVE AVERAGE TOWARD THE
WEEKEND. NO RAIN IS EXPECTED THROUGH FRIDAY WITH PLENTY OF SUNSHINE
AND ALL AROUND PLEASANT WEATHER. MEDIUM RANGE MODELS DO SUGGEST
PATTERN COULD TURN POTENTIALLY STORMIER NEXT WEEKEND AS FLOW
FLATTENS OUT A BIT AND WARM AIR ADVECTION STRENGTHENS IN ADVANCE OF
TROUGH DIGGING INTO THE NORTHERN/CENTRAL PLAINS. STILL SOME
DISAGREEMENT IN THE DETAILS...NOT SURPRISINGLY THIS FAR OUT...SO
KEPT POPS MODEST FOR NOW UNTIL DETAILS CAN BE BETTER PINNED DOWN IN
THE COMING DAYS.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* WIND DIRECTION AND SPEEDS ASSOCIATED WITH FROPA THIS AFTERNOON
  ...NORTH-NORTHEAST WIND LOOKING LIKELY BY LATE AFTERNOON...WIND
  SPEEDS COULD REMAIN UNDER 10 KT.
* CIGS LOWERING TO MVFR WITH SHRA.

KJB

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

A COLD FRONT WILL SAG SOUTHWARD ACROSS NORTHERN ILLINOIS THROUGH
THE AFTERNOON. THIS WILL LEAD TO A NORTHERLY WIND SHIFT ACROSS THE
TERMINALS BY MID TO LATE THIS AFTERNOON. THE EASTERN TAF SITES
COULD EXPERIENCE A BIT MORE OF A NORTHEASTERLY COMPONENT.
HOWEVER...WIND SPEEDS OVERALL APPEAR THAT THEY MAY REMAIN AT OR
UNDER 10 KT WITH THIS NORTHERLY WIND SHIFT.

SCATTERED SHOWERS ARE ALSO EXPECTED ACROSS THE REGION OVER THE
NEXT SEVERAL HOURS AS THIS FRONT...AND AN UPPER LEVEL DISTURBANCE
MOVES OVER THE AREA. ALTHOUGH THESE SHOWERS WILL BE LIGHT...SOME
LOWER CIGS INTO THE LOWER MVFR RANGE MAY DEVELOP FOR A PERIOD THIS
AFTERNOON.

SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA TONIGHT INTO
TUESDAY. THIS WILL RESULT IN CLEARING SKIES THIS EVENING...AND
LIGHT WINDS INTO TUESDAY. SOME PATCHY FOG IS POSSIBLE
OVERNIGHT...MAINLY TO THE WEST AND SOUTH OF THE MAIN CHICAGO
TERMINALS. A LAKE BREEZE MAY DEVELOP ON TUESDAY AFTERNOON WITH THE
LIGHT WIND PATTERN. HOWEVER...CONFIDENCE ON HOW FAR INLAND THIS
FEATURE WOULD PUSH INLAND IS TOO LOW TO ADD A MENTION IN THE
LATEST 30 HOUR ORD TAF.

KJB


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM TO HIGH CONFIDENCE IN WIND DIRECTION...LOW-MEDIUM THAT WINDS
  WILL GET AS HIGH AS 10 KT LATE THIS AFTERNOON.
* LOW-MEDIUM CONFIDENCE IN SHRA/MVFR TIMING.

KJB

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

TUESDAY NIGHT THROUGH FRIDAY...PRIMARILY VFR.
SATURDAY THROUGH SUNDAY...PERIODIC CHANCES FOR THUNDERSTORMS.

BMD

&&

.MARINE...
303 AM CDT

LOW PRESSURE NEAR JAMES BAY THIS MORNING WILL DRAG A COLD FRONT
ACROSS LAKE MICHIGAN. WINDS WILL TURN NORTHWEST TO NORTH BEHIND THE
FRONT...AND MAY BRIEFLY INCREASE INTO THE 20 TO 25 KT RANGE
ESPECIALLY ON THE SOUTH END OF THE LAKE THIS EVENING. HIGH PRESSURE
WILL BUILD IN BEHIND THE FRONT ALLOWING WINDS TO REMAIN MODEST FOR A
PERIOD BEFORE SOUTHWEST FLOW BEGINS TO FRESHEN UP AGAIN OVER THE
NORTH HALF OF LAKE MICHIGAN MIDDAY TUESDAY. ANOTHER COLD FRONT WILL
DIVE SOUTH ACROSS LAKE MICHIGAN ON WEDNESDAY TURNING WINDS NORTH TO
NORTHEAST AND INCREASING FOR A SHORT PERIOD TO AROUND 30 KT ONCE
AGAIN.

BMD

&&

.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 151708
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1208 PM CDT MON SEP 15 2014

.DISCUSSION...
311 AM CDT

DISMAL AND SHOWERY WEATHER ON TAP TODAY FOLLOWED BY PRETTY
SPECTACULAR WEATHER THE REMAINDER OF THE WEEK.

FAIRLY ENERGETIC SHORTWAVE TROUGH OVER THE DAKOTAS THIS MORNING
WILL DIG SOUTHEASTWARD INTO THE LOWER LAKES LATER TODAY BEFORE
SHIFTING EAST OF THE REGION TONIGHT. LOW-MID LEVEL FRONTOGENESIS IN
THE RIGHT ENTRANCE REGION OF 100KT+ 250MB JET IS ALREADY SUPPORTING
A BAND OF RAIN FROM EASTERN SD EAST INTO CENTRAL WISCONSIN. IN
ADDITION...SECOND AREA OF SHOWERS AND THUNDERSTORMS DEVELOPING OVER
IOWA IN ASSOCIATED WITH STRENGTHENING LOW LEVEL JET/WAA. THESE TWO
REGIONS OF PRECIP ARE LIKELY TO CONGEAL AND SPREAD ACROSS OUR CWA
LATER THIS MORNING AND CONTINUE INTO THE AFTERNOON. SOME WEAK
ELEVATED INSTABILITY COULD SUPPORT AN ISOLATED THUNDERSTORM SOUTH
BUT CHANCES AND AREAL COVERAGE OF THUNDER APPEAR LOW. AS TROUGH AXIS
TRANSLATE QUICKLY EASTWARD LOOK FOR RAIN/SHOWERS TO END...POSSIBLY
AS A PERIOD OF DRIZZLE LATER THIS AFTERNOON. TEMPS ARE TRICKY AND
WILL HINGE ON HOW MUCH THEY CAN RISE BEFORE RAIN STARTS AND THEY
LOSE A LITTLE GROUND THIS AFTERNOON.

STRONG SUBSIDENCE AND DRYING ARE FORECAST IN THE WAKE OF THE TROUGH
WHICH SHOULD LEAD TO RAPID CLEARING THIS EVENING WITH ANOTHER FAIRLY
HEALTHY PUSH OF EARLY SEASON COLD AIR ARRIVING TONIGHT. ONCE AGAIN
LOOKING FOR LOWS TO DROP INTO THE 30S OVER WESTERN PORTIONS OF THE
CWA...PARTICULARLY THE TYPICALLY FAVORED COOL SPOTS. CANT RULE OUT A
TOUCH OF FROST IN THE SHELTERED COOL SPOTS...ESPECIALLY ON ELEVATED
OBJECTS...BUT NOT EXPECTED TO BE A BIG ENOUGH DEAL TO INCLUDE IN
GRIDS.

TUESDAY LOOKS TO BE SUNNY AND UNSEASONABLY COOL...BUT NOT AS CHILLY
AS LAST WEEK. A SLOW BUT STEADY WARMING TREND WILL COMMENCE
WEDNESDAY AND CONTINUE INTO THE WEEKEND WITH HIGHS EVENTUALLY
REBOUNDING BACK TOWARD IF NOT A BIT ABOVE AVERAGE TOWARD THE
WEEKEND. NO RAIN IS EXPECTED THROUGH FRIDAY WITH PLENTY OF SUNSHINE
AND ALL AROUND PLEASANT WEATHER. MEDIUM RANGE MODELS DO SUGGEST
PATTERN COULD TURN POTENTIALLY STORMIER NEXT WEEKEND AS FLOW
FLATTENS OUT A BIT AND WARM AIR ADVECTION STRENGTHENS IN ADVANCE OF
TROUGH DIGGING INTO THE NORTHERN/CENTRAL PLAINS. STILL SOME
DISAGREEMENT IN THE DETAILS...NOT SURPRISINGLY THIS FAR OUT...SO
KEPT POPS MODEST FOR NOW UNTIL DETAILS CAN BE BETTER PINNED DOWN IN
THE COMING DAYS.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* WIND DIRECTION AND SPEEDS ASSOCIATED WITH FROPA THIS AFTERNOON
  ...NORTH-NORTHEAST WIND LOOKING LIKELY BY LATE AFTERNOON...WIND
  SPEEDS COULD REMAIN UNDER 10 KT.
* CIGS LOWERING TO MVFR WITH SHRA.

KJB

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

A COLD FRONT WILL SAG SOUTHWARD ACROSS NORTHERN ILLINOIS THROUGH
THE AFTERNOON. THIS WILL LEAD TO A NORTHERLY WIND SHIFT ACROSS THE
TERMINALS BY MID TO LATE THIS AFTERNOON. THE EASTERN TAF SITES
COULD EXPERIENCE A BIT MORE OF A NORTHEASTERLY COMPONENT.
HOWEVER...WIND SPEEDS OVERALL APPEAR THAT THEY MAY REMAIN AT OR
UNDER 10 KT WITH THIS NORTHERLY WIND SHIFT.

SCATTERED SHOWERS ARE ALSO EXPECTED ACROSS THE REGION OVER THE
NEXT SEVERAL HOURS AS THIS FRONT...AND AN UPPER LEVEL DISTURBANCE
MOVES OVER THE AREA. ALTHOUGH THESE SHOWERS WILL BE LIGHT...SOME
LOWER CIGS INTO THE LOWER MVFR RANGE MAY DEVELOP FOR A PERIOD THIS
AFTERNOON.

SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA TONIGHT INTO
TUESDAY. THIS WILL RESULT IN CLEARING SKIES THIS EVENING...AND
LIGHT WINDS INTO TUESDAY. SOME PATCHY FOG IS POSSIBLE
OVERNIGHT...MAINLY TO THE WEST AND SOUTH OF THE MAIN CHICAGO
TERMINALS. A LAKE BREEZE MAY DEVELOP ON TUESDAY AFTERNOON WITH THE
LIGHT WIND PATTERN. HOWEVER...CONFIDENCE ON HOW FAR INLAND THIS
FEATURE WOULD PUSH INLAND IS TOO LOW TO ADD A MENTION IN THE
LATEST 30 HOUR ORD TAF.

KJB


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM TO HIGH CONFIDENCE IN WIND DIRECTION...LOW-MEDIUM THAT WINDS
  WILL GET AS HIGH AS 10 KT LATE THIS AFTERNOON.
* LOW-MEDIUM CONFIDENCE IN SHRA/MVFR TIMING.

KJB

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

TUESDAY NIGHT THROUGH FRIDAY...PRIMARILY VFR.
SATURDAY THROUGH SUNDAY...PERIODIC CHANCES FOR THUNDERSTORMS.

BMD

&&

.MARINE...
303 AM CDT

LOW PRESSURE NEAR JAMES BAY THIS MORNING WILL DRAG A COLD FRONT
ACROSS LAKE MICHIGAN. WINDS WILL TURN NORTHWEST TO NORTH BEHIND THE
FRONT...AND MAY BRIEFLY INCREASE INTO THE 20 TO 25 KT RANGE
ESPECIALLY ON THE SOUTH END OF THE LAKE THIS EVENING. HIGH PRESSURE
WILL BUILD IN BEHIND THE FRONT ALLOWING WINDS TO REMAIN MODEST FOR A
PERIOD BEFORE SOUTHWEST FLOW BEGINS TO FRESHEN UP AGAIN OVER THE
NORTH HALF OF LAKE MICHIGAN MIDDAY TUESDAY. ANOTHER COLD FRONT WILL
DIVE SOUTH ACROSS LAKE MICHIGAN ON WEDNESDAY TURNING WINDS NORTH TO
NORTHEAST AND INCREASING FOR A SHORT PERIOD TO AROUND 30 KT ONCE
AGAIN.

BMD

&&

.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 151708
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1208 PM CDT MON SEP 15 2014

.DISCUSSION...
311 AM CDT

DISMAL AND SHOWERY WEATHER ON TAP TODAY FOLLOWED BY PRETTY
SPECTACULAR WEATHER THE REMAINDER OF THE WEEK.

FAIRLY ENERGETIC SHORTWAVE TROUGH OVER THE DAKOTAS THIS MORNING
WILL DIG SOUTHEASTWARD INTO THE LOWER LAKES LATER TODAY BEFORE
SHIFTING EAST OF THE REGION TONIGHT. LOW-MID LEVEL FRONTOGENESIS IN
THE RIGHT ENTRANCE REGION OF 100KT+ 250MB JET IS ALREADY SUPPORTING
A BAND OF RAIN FROM EASTERN SD EAST INTO CENTRAL WISCONSIN. IN
ADDITION...SECOND AREA OF SHOWERS AND THUNDERSTORMS DEVELOPING OVER
IOWA IN ASSOCIATED WITH STRENGTHENING LOW LEVEL JET/WAA. THESE TWO
REGIONS OF PRECIP ARE LIKELY TO CONGEAL AND SPREAD ACROSS OUR CWA
LATER THIS MORNING AND CONTINUE INTO THE AFTERNOON. SOME WEAK
ELEVATED INSTABILITY COULD SUPPORT AN ISOLATED THUNDERSTORM SOUTH
BUT CHANCES AND AREAL COVERAGE OF THUNDER APPEAR LOW. AS TROUGH AXIS
TRANSLATE QUICKLY EASTWARD LOOK FOR RAIN/SHOWERS TO END...POSSIBLY
AS A PERIOD OF DRIZZLE LATER THIS AFTERNOON. TEMPS ARE TRICKY AND
WILL HINGE ON HOW MUCH THEY CAN RISE BEFORE RAIN STARTS AND THEY
LOSE A LITTLE GROUND THIS AFTERNOON.

STRONG SUBSIDENCE AND DRYING ARE FORECAST IN THE WAKE OF THE TROUGH
WHICH SHOULD LEAD TO RAPID CLEARING THIS EVENING WITH ANOTHER FAIRLY
HEALTHY PUSH OF EARLY SEASON COLD AIR ARRIVING TONIGHT. ONCE AGAIN
LOOKING FOR LOWS TO DROP INTO THE 30S OVER WESTERN PORTIONS OF THE
CWA...PARTICULARLY THE TYPICALLY FAVORED COOL SPOTS. CANT RULE OUT A
TOUCH OF FROST IN THE SHELTERED COOL SPOTS...ESPECIALLY ON ELEVATED
OBJECTS...BUT NOT EXPECTED TO BE A BIG ENOUGH DEAL TO INCLUDE IN
GRIDS.

TUESDAY LOOKS TO BE SUNNY AND UNSEASONABLY COOL...BUT NOT AS CHILLY
AS LAST WEEK. A SLOW BUT STEADY WARMING TREND WILL COMMENCE
WEDNESDAY AND CONTINUE INTO THE WEEKEND WITH HIGHS EVENTUALLY
REBOUNDING BACK TOWARD IF NOT A BIT ABOVE AVERAGE TOWARD THE
WEEKEND. NO RAIN IS EXPECTED THROUGH FRIDAY WITH PLENTY OF SUNSHINE
AND ALL AROUND PLEASANT WEATHER. MEDIUM RANGE MODELS DO SUGGEST
PATTERN COULD TURN POTENTIALLY STORMIER NEXT WEEKEND AS FLOW
FLATTENS OUT A BIT AND WARM AIR ADVECTION STRENGTHENS IN ADVANCE OF
TROUGH DIGGING INTO THE NORTHERN/CENTRAL PLAINS. STILL SOME
DISAGREEMENT IN THE DETAILS...NOT SURPRISINGLY THIS FAR OUT...SO
KEPT POPS MODEST FOR NOW UNTIL DETAILS CAN BE BETTER PINNED DOWN IN
THE COMING DAYS.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 18Z...

* WIND DIRECTION AND SPEEDS ASSOCIATED WITH FROPA THIS AFTERNOON
  ...NORTH-NORTHEAST WIND LOOKING LIKELY BY LATE AFTERNOON...WIND
  SPEEDS COULD REMAIN UNDER 10 KT.
* CIGS LOWERING TO MVFR WITH SHRA.

KJB

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

A COLD FRONT WILL SAG SOUTHWARD ACROSS NORTHERN ILLINOIS THROUGH
THE AFTERNOON. THIS WILL LEAD TO A NORTHERLY WIND SHIFT ACROSS THE
TERMINALS BY MID TO LATE THIS AFTERNOON. THE EASTERN TAF SITES
COULD EXPERIENCE A BIT MORE OF A NORTHEASTERLY COMPONENT.
HOWEVER...WIND SPEEDS OVERALL APPEAR THAT THEY MAY REMAIN AT OR
UNDER 10 KT WITH THIS NORTHERLY WIND SHIFT.

SCATTERED SHOWERS ARE ALSO EXPECTED ACROSS THE REGION OVER THE
NEXT SEVERAL HOURS AS THIS FRONT...AND AN UPPER LEVEL DISTURBANCE
MOVES OVER THE AREA. ALTHOUGH THESE SHOWERS WILL BE LIGHT...SOME
LOWER CIGS INTO THE LOWER MVFR RANGE MAY DEVELOP FOR A PERIOD THIS
AFTERNOON.

SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA TONIGHT INTO
TUESDAY. THIS WILL RESULT IN CLEARING SKIES THIS EVENING...AND
LIGHT WINDS INTO TUESDAY. SOME PATCHY FOG IS POSSIBLE
OVERNIGHT...MAINLY TO THE WEST AND SOUTH OF THE MAIN CHICAGO
TERMINALS. A LAKE BREEZE MAY DEVELOP ON TUESDAY AFTERNOON WITH THE
LIGHT WIND PATTERN. HOWEVER...CONFIDENCE ON HOW FAR INLAND THIS
FEATURE WOULD PUSH INLAND IS TOO LOW TO ADD A MENTION IN THE
LATEST 30 HOUR ORD TAF.

KJB


//ORD AND MDW CONFIDENCE...UPDATED 18Z...

* MEDIUM TO HIGH CONFIDENCE IN WIND DIRECTION...LOW-MEDIUM THAT WINDS
  WILL GET AS HIGH AS 10 KT LATE THIS AFTERNOON.
* LOW-MEDIUM CONFIDENCE IN SHRA/MVFR TIMING.

KJB

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

TUESDAY NIGHT THROUGH FRIDAY...PRIMARILY VFR.
SATURDAY THROUGH SUNDAY...PERIODIC CHANCES FOR THUNDERSTORMS.

BMD

&&

.MARINE...
303 AM CDT

LOW PRESSURE NEAR JAMES BAY THIS MORNING WILL DRAG A COLD FRONT
ACROSS LAKE MICHIGAN. WINDS WILL TURN NORTHWEST TO NORTH BEHIND THE
FRONT...AND MAY BRIEFLY INCREASE INTO THE 20 TO 25 KT RANGE
ESPECIALLY ON THE SOUTH END OF THE LAKE THIS EVENING. HIGH PRESSURE
WILL BUILD IN BEHIND THE FRONT ALLOWING WINDS TO REMAIN MODEST FOR A
PERIOD BEFORE SOUTHWEST FLOW BEGINS TO FRESHEN UP AGAIN OVER THE
NORTH HALF OF LAKE MICHIGAN MIDDAY TUESDAY. ANOTHER COLD FRONT WILL
DIVE SOUTH ACROSS LAKE MICHIGAN ON WEDNESDAY TURNING WINDS NORTH TO
NORTHEAST AND INCREASING FOR A SHORT PERIOD TO AROUND 30 KT ONCE
AGAIN.

BMD

&&

.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 151640
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1140 AM CDT Mon Sep 15 2014

.UPDATE...
ISSUED AT 1135 AM CDT MON SEP 15 2014

Minor adjustments to the forecast as showers and thunderstorms
move through Central Illinois ahead of an advancing cold front.
Though severe weather is not anticipated, locally heavy rain and
frequent lightning will accompany the storms this morning.
Temperatures across the northern portions of the CWA will struggle
into the lower 60s, with warmer temps along and south of I-70. No
major updates anticipated at this time.

&&

.SHORT TERM...(Today)
ISSUED AT 301 AM CDT MON SEP 15 2014

Main concern for today is shower/storm timing/chances associated
with the passage of a weak cold front and driving upper level
energy. The upper level forcing is somewhat complicated as it will
be provided by two separate disturbances. The first/weaker wave is
tracking east across the central Plains, while the second/stronger
wave is diving across the northern Plains. The second wave should
end up being the dominant feature for us, although both waves should
tend to shear out to some degree as they push into the confluent
flow across the Midwest.

The best forcing/frontal arrival have slowed some from previous
forecast, with the front not expected to clear the entire forecast
area until this evening. This slower arrival will also delay the
better chances for precipitation until the midday/afternoon hours.
Have expanded thunder mention to the entire forecast area today
given the steep mid-level lapse rates on forecast soundings
area wide. This north/east shift of thunder chances is also supported
by storms currently tracking east across southern Iowa. These storms
were located on the nose of a 25kt low-level jet in advance of the
central Plains wave. The forcing of the LLJ and central Plains wave
should weaken before reaching the local area, however it is expected
to be replaced by upper-level divergence/mid-level frontogenesis as
a jet streak ahead of the northern Plains wave arrives. A fairly
wide N-S temperature range is likely across the forecast area today
considering the fairly early arrival of the front/precipitation in
our northwest counties, compared to the evening frontal arrival
across southeast Illinois.

&&

.LONG TERM...(Tonight through Sunday)
ISSUED AT 301 AM CDT MON SEP 15 2014

Cold front should reach the I-70 corridor by sunset and be out of
the forecast area shortly afterward, taking the rain with it. Fairly
sharp clearing expected behind the front as high pressure builds in,
but clouds will linger much of the night in southeast Illinois.

Quiet midweek period expected as the high drifts across the Midwest.
Evening models have various interpretations of some convective
activity to our southwest on Wednesday, along the periphery of some
upper ridging across the Rockies. but all models keep it in Missouri
and will thus keep our forecast dry. Slow moderating trend in
temperatures with lower 70s widespread by Thursday.

Upper ridge breaks down late in the week before rebuilding along the
West Coast late in the weekend. Longer range models dig a sharpening
upper wave across the mid and upper Mississippi Valley by Saturday
night, with rain chances mainly focused in the Saturday afternoon
and evening time frame. Beyond that, the models show quite a bit of
divergence in the evolution of this wave. The latest ECMWF model
forms a closed low over Lake Superior Saturday night and drives a
large slug of cooler air across the Midwest later in the weekend,
while the steadier GFS is much more progressive and shows much less
of a temperature change. That sharper scenario is more of a recent
development and thus for now have only shown some small decrease in
temperatures for Sunday and Monday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
ISSUED AT 648 AM CDT MON SEP 15 2014

Spotty showers and thunderstorms have developed across northern
Illinois and upstream toward a cold front cutting northeast to
southwest across Iowa. The coverage is expected to increase over
the next few hours, with shower/storm chances lingering until the
cold front passes later today. Have included a VCTS at all central
Illinois terminals until FROPA, and have also included a 4 hour
tempo for showers for the four hours preceding FROPA when
rainfall coverage should be greatest. May need to amend to add a
TEMPO for thunder as well, but do not want to overdo the thunder
coverages until its ultimate extent is more clear. Carried VCSH
for a few hours post FROPA due to some guidance suggesting showers
may linger for a time.

VFR conditions to start the period may degrade to MVFR with the
steadier showers/storms. Then, expect MVFR conditions to develop
due to moisture/clouds trapped beneath the post frontal subsidence
inversion. Current thinking is that skies should clear before the
end of the period, but confidence it the timing of the clearing is
not high.


&&

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

$$

UPDATE...HJS
SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...BAK







000
FXUS63 KILX 151640
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1140 AM CDT Mon Sep 15 2014

.UPDATE...
ISSUED AT 1135 AM CDT MON SEP 15 2014

Minor adjustments to the forecast as showers and thunderstorms
move through Central Illinois ahead of an advancing cold front.
Though severe weather is not anticipated, locally heavy rain and
frequent lightning will accompany the storms this morning.
Temperatures across the northern portions of the CWA will struggle
into the lower 60s, with warmer temps along and south of I-70. No
major updates anticipated at this time.

&&

.SHORT TERM...(Today)
ISSUED AT 301 AM CDT MON SEP 15 2014

Main concern for today is shower/storm timing/chances associated
with the passage of a weak cold front and driving upper level
energy. The upper level forcing is somewhat complicated as it will
be provided by two separate disturbances. The first/weaker wave is
tracking east across the central Plains, while the second/stronger
wave is diving across the northern Plains. The second wave should
end up being the dominant feature for us, although both waves should
tend to shear out to some degree as they push into the confluent
flow across the Midwest.

The best forcing/frontal arrival have slowed some from previous
forecast, with the front not expected to clear the entire forecast
area until this evening. This slower arrival will also delay the
better chances for precipitation until the midday/afternoon hours.
Have expanded thunder mention to the entire forecast area today
given the steep mid-level lapse rates on forecast soundings
area wide. This north/east shift of thunder chances is also supported
by storms currently tracking east across southern Iowa. These storms
were located on the nose of a 25kt low-level jet in advance of the
central Plains wave. The forcing of the LLJ and central Plains wave
should weaken before reaching the local area, however it is expected
to be replaced by upper-level divergence/mid-level frontogenesis as
a jet streak ahead of the northern Plains wave arrives. A fairly
wide N-S temperature range is likely across the forecast area today
considering the fairly early arrival of the front/precipitation in
our northwest counties, compared to the evening frontal arrival
across southeast Illinois.

&&

.LONG TERM...(Tonight through Sunday)
ISSUED AT 301 AM CDT MON SEP 15 2014

Cold front should reach the I-70 corridor by sunset and be out of
the forecast area shortly afterward, taking the rain with it. Fairly
sharp clearing expected behind the front as high pressure builds in,
but clouds will linger much of the night in southeast Illinois.

Quiet midweek period expected as the high drifts across the Midwest.
Evening models have various interpretations of some convective
activity to our southwest on Wednesday, along the periphery of some
upper ridging across the Rockies. but all models keep it in Missouri
and will thus keep our forecast dry. Slow moderating trend in
temperatures with lower 70s widespread by Thursday.

Upper ridge breaks down late in the week before rebuilding along the
West Coast late in the weekend. Longer range models dig a sharpening
upper wave across the mid and upper Mississippi Valley by Saturday
night, with rain chances mainly focused in the Saturday afternoon
and evening time frame. Beyond that, the models show quite a bit of
divergence in the evolution of this wave. The latest ECMWF model
forms a closed low over Lake Superior Saturday night and drives a
large slug of cooler air across the Midwest later in the weekend,
while the steadier GFS is much more progressive and shows much less
of a temperature change. That sharper scenario is more of a recent
development and thus for now have only shown some small decrease in
temperatures for Sunday and Monday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
ISSUED AT 648 AM CDT MON SEP 15 2014

Spotty showers and thunderstorms have developed across northern
Illinois and upstream toward a cold front cutting northeast to
southwest across Iowa. The coverage is expected to increase over
the next few hours, with shower/storm chances lingering until the
cold front passes later today. Have included a VCTS at all central
Illinois terminals until FROPA, and have also included a 4 hour
tempo for showers for the four hours preceding FROPA when
rainfall coverage should be greatest. May need to amend to add a
TEMPO for thunder as well, but do not want to overdo the thunder
coverages until its ultimate extent is more clear. Carried VCSH
for a few hours post FROPA due to some guidance suggesting showers
may linger for a time.

VFR conditions to start the period may degrade to MVFR with the
steadier showers/storms. Then, expect MVFR conditions to develop
due to moisture/clouds trapped beneath the post frontal subsidence
inversion. Current thinking is that skies should clear before the
end of the period, but confidence it the timing of the clearing is
not high.


&&

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

$$

UPDATE...HJS
SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...BAK







000
FXUS63 KILX 151640
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1140 AM CDT Mon Sep 15 2014

.UPDATE...
ISSUED AT 1135 AM CDT MON SEP 15 2014

Minor adjustments to the forecast as showers and thunderstorms
move through Central Illinois ahead of an advancing cold front.
Though severe weather is not anticipated, locally heavy rain and
frequent lightning will accompany the storms this morning.
Temperatures across the northern portions of the CWA will struggle
into the lower 60s, with warmer temps along and south of I-70. No
major updates anticipated at this time.

&&

.SHORT TERM...(Today)
ISSUED AT 301 AM CDT MON SEP 15 2014

Main concern for today is shower/storm timing/chances associated
with the passage of a weak cold front and driving upper level
energy. The upper level forcing is somewhat complicated as it will
be provided by two separate disturbances. The first/weaker wave is
tracking east across the central Plains, while the second/stronger
wave is diving across the northern Plains. The second wave should
end up being the dominant feature for us, although both waves should
tend to shear out to some degree as they push into the confluent
flow across the Midwest.

The best forcing/frontal arrival have slowed some from previous
forecast, with the front not expected to clear the entire forecast
area until this evening. This slower arrival will also delay the
better chances for precipitation until the midday/afternoon hours.
Have expanded thunder mention to the entire forecast area today
given the steep mid-level lapse rates on forecast soundings
area wide. This north/east shift of thunder chances is also supported
by storms currently tracking east across southern Iowa. These storms
were located on the nose of a 25kt low-level jet in advance of the
central Plains wave. The forcing of the LLJ and central Plains wave
should weaken before reaching the local area, however it is expected
to be replaced by upper-level divergence/mid-level frontogenesis as
a jet streak ahead of the northern Plains wave arrives. A fairly
wide N-S temperature range is likely across the forecast area today
considering the fairly early arrival of the front/precipitation in
our northwest counties, compared to the evening frontal arrival
across southeast Illinois.

&&

.LONG TERM...(Tonight through Sunday)
ISSUED AT 301 AM CDT MON SEP 15 2014

Cold front should reach the I-70 corridor by sunset and be out of
the forecast area shortly afterward, taking the rain with it. Fairly
sharp clearing expected behind the front as high pressure builds in,
but clouds will linger much of the night in southeast Illinois.

Quiet midweek period expected as the high drifts across the Midwest.
Evening models have various interpretations of some convective
activity to our southwest on Wednesday, along the periphery of some
upper ridging across the Rockies. but all models keep it in Missouri
and will thus keep our forecast dry. Slow moderating trend in
temperatures with lower 70s widespread by Thursday.

Upper ridge breaks down late in the week before rebuilding along the
West Coast late in the weekend. Longer range models dig a sharpening
upper wave across the mid and upper Mississippi Valley by Saturday
night, with rain chances mainly focused in the Saturday afternoon
and evening time frame. Beyond that, the models show quite a bit of
divergence in the evolution of this wave. The latest ECMWF model
forms a closed low over Lake Superior Saturday night and drives a
large slug of cooler air across the Midwest later in the weekend,
while the steadier GFS is much more progressive and shows much less
of a temperature change. That sharper scenario is more of a recent
development and thus for now have only shown some small decrease in
temperatures for Sunday and Monday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
ISSUED AT 648 AM CDT MON SEP 15 2014

Spotty showers and thunderstorms have developed across northern
Illinois and upstream toward a cold front cutting northeast to
southwest across Iowa. The coverage is expected to increase over
the next few hours, with shower/storm chances lingering until the
cold front passes later today. Have included a VCTS at all central
Illinois terminals until FROPA, and have also included a 4 hour
tempo for showers for the four hours preceding FROPA when
rainfall coverage should be greatest. May need to amend to add a
TEMPO for thunder as well, but do not want to overdo the thunder
coverages until its ultimate extent is more clear. Carried VCSH
for a few hours post FROPA due to some guidance suggesting showers
may linger for a time.

VFR conditions to start the period may degrade to MVFR with the
steadier showers/storms. Then, expect MVFR conditions to develop
due to moisture/clouds trapped beneath the post frontal subsidence
inversion. Current thinking is that skies should clear before the
end of the period, but confidence it the timing of the clearing is
not high.


&&

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

$$

UPDATE...HJS
SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...BAK







000
FXUS63 KILX 151640
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1140 AM CDT Mon Sep 15 2014

.UPDATE...
ISSUED AT 1135 AM CDT MON SEP 15 2014

Minor adjustments to the forecast as showers and thunderstorms
move through Central Illinois ahead of an advancing cold front.
Though severe weather is not anticipated, locally heavy rain and
frequent lightning will accompany the storms this morning.
Temperatures across the northern portions of the CWA will struggle
into the lower 60s, with warmer temps along and south of I-70. No
major updates anticipated at this time.

&&

.SHORT TERM...(Today)
ISSUED AT 301 AM CDT MON SEP 15 2014

Main concern for today is shower/storm timing/chances associated
with the passage of a weak cold front and driving upper level
energy. The upper level forcing is somewhat complicated as it will
be provided by two separate disturbances. The first/weaker wave is
tracking east across the central Plains, while the second/stronger
wave is diving across the northern Plains. The second wave should
end up being the dominant feature for us, although both waves should
tend to shear out to some degree as they push into the confluent
flow across the Midwest.

The best forcing/frontal arrival have slowed some from previous
forecast, with the front not expected to clear the entire forecast
area until this evening. This slower arrival will also delay the
better chances for precipitation until the midday/afternoon hours.
Have expanded thunder mention to the entire forecast area today
given the steep mid-level lapse rates on forecast soundings
area wide. This north/east shift of thunder chances is also supported
by storms currently tracking east across southern Iowa. These storms
were located on the nose of a 25kt low-level jet in advance of the
central Plains wave. The forcing of the LLJ and central Plains wave
should weaken before reaching the local area, however it is expected
to be replaced by upper-level divergence/mid-level frontogenesis as
a jet streak ahead of the northern Plains wave arrives. A fairly
wide N-S temperature range is likely across the forecast area today
considering the fairly early arrival of the front/precipitation in
our northwest counties, compared to the evening frontal arrival
across southeast Illinois.

&&

.LONG TERM...(Tonight through Sunday)
ISSUED AT 301 AM CDT MON SEP 15 2014

Cold front should reach the I-70 corridor by sunset and be out of
the forecast area shortly afterward, taking the rain with it. Fairly
sharp clearing expected behind the front as high pressure builds in,
but clouds will linger much of the night in southeast Illinois.

Quiet midweek period expected as the high drifts across the Midwest.
Evening models have various interpretations of some convective
activity to our southwest on Wednesday, along the periphery of some
upper ridging across the Rockies. but all models keep it in Missouri
and will thus keep our forecast dry. Slow moderating trend in
temperatures with lower 70s widespread by Thursday.

Upper ridge breaks down late in the week before rebuilding along the
West Coast late in the weekend. Longer range models dig a sharpening
upper wave across the mid and upper Mississippi Valley by Saturday
night, with rain chances mainly focused in the Saturday afternoon
and evening time frame. Beyond that, the models show quite a bit of
divergence in the evolution of this wave. The latest ECMWF model
forms a closed low over Lake Superior Saturday night and drives a
large slug of cooler air across the Midwest later in the weekend,
while the steadier GFS is much more progressive and shows much less
of a temperature change. That sharper scenario is more of a recent
development and thus for now have only shown some small decrease in
temperatures for Sunday and Monday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
ISSUED AT 648 AM CDT MON SEP 15 2014

Spotty showers and thunderstorms have developed across northern
Illinois and upstream toward a cold front cutting northeast to
southwest across Iowa. The coverage is expected to increase over
the next few hours, with shower/storm chances lingering until the
cold front passes later today. Have included a VCTS at all central
Illinois terminals until FROPA, and have also included a 4 hour
tempo for showers for the four hours preceding FROPA when
rainfall coverage should be greatest. May need to amend to add a
TEMPO for thunder as well, but do not want to overdo the thunder
coverages until its ultimate extent is more clear. Carried VCSH
for a few hours post FROPA due to some guidance suggesting showers
may linger for a time.

VFR conditions to start the period may degrade to MVFR with the
steadier showers/storms. Then, expect MVFR conditions to develop
due to moisture/clouds trapped beneath the post frontal subsidence
inversion. Current thinking is that skies should clear before the
end of the period, but confidence it the timing of the clearing is
not high.


&&

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

$$

UPDATE...HJS
SHORT TERM...BAK
LONG TERM...GEELHART
AVIATION...BAK







000
FXUS63 KLOT 151620
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1120 AM CDT MON SEP 15 2014

.DISCUSSION...
311 AM CDT

DISMAL AND SHOWERY WEATHER ON TAP TODAY FOLLOWED BY PRETTY
SPECTACULAR WEATHER THE REMAINDER OF THE WEEK.

FAIRLY ENERGETIC SHORTWAVE TROUGH OVER THE DAKOTAS THIS MORNING
WILL DIG SOUTHEASTWARD INTO THE LOWER LAKES LATER TODAY BEFORE
SHIFTING EAST OF THE REGION TONIGHT. LOW-MID LEVEL FRONTOGENESIS IN
THE RIGHT ENTRANCE REGION OF 100KT+ 250MB JET IS ALREADY SUPPORTING
A BAND OF RAIN FROM EASTERN SD EAST INTO CENTRAL WISCONSIN. IN
ADDITION...SECOND AREA OF SHOWERS AND THUNDERSTORMS DEVELOPING OVER
IOWA IN ASSOCIATED WITH STRENGTHENING LOW LEVEL JET/WAA. THESE TWO
REGIONS OF PRECIP ARE LIKELY TO CONGEAL AND SPREAD ACROSS OUR CWA
LATER THIS MORNING AND CONTINUE INTO THE AFTERNOON. SOME WEAK
ELEVATED INSTABILITY COULD SUPPORT AN ISOLATED THUNDERSTORM SOUTH
BUT CHANCES AND AREAL COVERAGE OF THUNDER APPEAR LOW. AS TROUGH AXIS
TRANSLATE QUICKLY EASTWARD LOOK FOR RAIN/SHOWERS TO END...POSSIBLY
AS A PERIOD OF DRIZZLE LATER THIS AFTERNOON. TEMPS ARE TRICKY AND
WILL HINGE ON HOW MUCH THEY CAN RISE BEFORE RAIN STARTS AND THEY
LOSE A LITTLE GROUND THIS AFTERNOON.

STRONG SUBSIDENCE AND DRYING ARE FORECAST IN THE WAKE OF THE TROUGH
WHICH SHOULD LEAD TO RAPID CLEARING THIS EVENING WITH ANOTHER FAIRLY
HEALTHY PUSH OF EARLY SEASON COLD AIR ARRIVING TONIGHT. ONCE AGAIN
LOOKING FOR LOWS TO DROP INTO THE 30S OVER WESTERN PORTIONS OF THE
CWA...PARTICULARLY THE TYPICALLY FAVORED COOL SPOTS. CANT RULE OUT A
TOUCH OF FROST IN THE SHELTERED COOL SPOTS...ESPECIALLY ON ELEVATED
OBJECTS...BUT NOT EXPECTED TO BE A BIG ENOUGH DEAL TO INCLUDE IN
GRIDS.

TUESDAY LOOKS TO BE SUNNY AND UNSEASONABLY COOL...BUT NOT AS CHILLY
AS LAST WEEK. A SLOW BUT STEADY WARMING TREND WILL COMMENCE
WEDNESDAY AND CONTINUE INTO THE WEEKEND WITH HIGHS EVENTUALLY
REBOUNDING BACK TOWARD IF NOT A BIT ABOVE AVERAGE TOWARD THE
WEEKEND. NO RAIN IS EXPECTED THROUGH FRIDAY WITH PLENTY OF SUNSHINE
AND ALL AROUND PLEASANT WEATHER. MEDIUM RANGE MODELS DO SUGGEST
PATTERN COULD TURN POTENTIALLY STORMIER NEXT WEEKEND AS FLOW
FLATTENS OUT A BIT AND WARM AIR ADVECTION STRENGTHENS IN ADVANCE OF
TROUGH DIGGING INTO THE NORTHERN/CENTRAL PLAINS. STILL SOME
DISAGREEMENT IN THE DETAILS...NOT SURPRISINGLY THIS FAR OUT...SO
KEPT POPS MODEST FOR NOW UNTIL DETAILS CAN BE BETTER PINNED DOWN IN
THE COMING DAYS.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* WIND DIRECTION AND SPEEDS ASSOCIATED WITH FROPA THIS AFTERNOON
  ...NORTH-NORTHEAST WIND LOOKING LIKELY BY LATE AFTERNOON...WIND
  SPEEDS COULD REMAIN UNDER 10 KT.
* CIGS LOWERING TO MVFR WITH SHRA.

BMD/KB

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

A COLD FRONT STRETCHES ACROSS CENTRAL LAKE MICHIGAN INTO CENTRAL
IOWA EARLY THIS MORNING AND WILL SLOWLY SAG TOWARDS THE REGION
THROUGH THE DAY. OUT AHEAD...A FEW EARLY MORNING HIGH BASED SHOWERS
AND THUNDERSTORMS HAVE DEVELOPED ASSOCIATED WITH A MID LEVEL SPEED
MAX. MOST INTENSE ACTIVITY THUS FAR HAS MOSTLY BEEN FOCUSED SOUTH OF
THE TERMINALS THIS MORNING BUT THE AREA OF SHRA/TSRA MOVING INTO
NORTHWEST IL WILL ARRIVE AT THE TERMINALS OVER THE NEXT FEW HOURS.
THERE IS SOME VERY MODEST INSTABILITY WITH EQUILIBRIUM LEVELS DEEP
ENOUGH TO SUPPORT AT LEAST AN ISOLATED LIGHTNING THREAT BUT FOR NOW
LOW COVERAGE WOULD PRECLUDE MENTION OF TS IN TAF AND WILL MAINTAIN
SHRA. AS THE COLD FRONT SAGS SOUTH ACROSS THE TERMINALS LATER
TODAY...GUIDANCE HAS COME INTO BETTER AGREEMENT THAT THERE WILL BE A
WIND SHIFT TO THE N...POSSIBLY NNE...BEFORE WINDS SETTLE BACK TO A
NW DIRECTION LATER TODAY. THERE MAY BE A BRIEF UPTICK IN THE WINDS
MID AFTERNOON INTO THE 10-12KT RANGE. CIGS WILL ALSO DECREASE AS THE
FRONTAL TROUGH APPROACHES WITH THE POTENTIAL FOR SEVERAL HOURS OF
MVFR CIGS THIS AFTERNOON AND EARLY EVENING. DRIER AIR MOVING IN THIS
EVENING SHOULD ALLOW CIGS TO SCATTER OUT FOR TONIGHT WITH A RETURN
TO VFR CONDITIONS. WINDS ARE EXPECTED TO DIMINISH OVERNIGHT AND
DEPENDING ON HOW QUICKLY SKIES CLEAR WILL HAVE TO KEEP AN EYE ON THE
FOG POTENTIAL...ESPECIALLY AT RFD WITH FUTURE TAF UPDATES.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* MEDIUM TO HIGH CONFIDENCE IN WIND DIRECTION...LOW-MEDIUM THAT WINDS
  WILL GET AS HIGH AS 10 KT LATE THIS AFTERNOON.
* LOW-MEDIUM CONFIDENCE IN SHRA/MVFR TIMING.

BMD/KB

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

TUESDAY NIGHT THROUGH FRIDAY...PRIMARILY VFR.
SATURDAY THROUGH SUNDAY...PERIODIC CHANCES FOR THUNDERSTORMS.

BMD

&&

.MARINE...
303 AM CDT

LOW PRESSURE NEAR JAMES BAY THIS MORNING WILL DRAG A COLD FRONT
ACROSS LAKE MICHIGAN. WINDS WILL TURN NORTHWEST TO NORTH BEHIND THE
FRONT...AND MAY BRIEFLY INCREASE INTO THE 20 TO 25 KT RANGE
ESPECIALLY ON THE SOUTH END OF THE LAKE THIS EVENING. HIGH PRESSURE
WILL BUILD IN BEHIND THE FRONT ALLOWING WINDS TO REMAIN MODEST FOR A
PERIOD BEFORE SOUTHWEST FLOW BEGINS TO FRESHEN UP AGAIN OVER THE
NORTH HALF OF LAKE MICHIGAN MIDDAY TUESDAY. ANOTHER COLD FRONT WILL
DIVE SOUTH ACROSS LAKE MICHIGAN ON WEDNESDAY TURNING WINDS NORTH TO
NORTHEAST AND INCREASING FOR A SHORT PERIOD TO AROUND 30 KT ONCE
AGAIN.

BMD

&&

.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 151620
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1120 AM CDT MON SEP 15 2014

.DISCUSSION...
311 AM CDT

DISMAL AND SHOWERY WEATHER ON TAP TODAY FOLLOWED BY PRETTY
SPECTACULAR WEATHER THE REMAINDER OF THE WEEK.

FAIRLY ENERGETIC SHORTWAVE TROUGH OVER THE DAKOTAS THIS MORNING
WILL DIG SOUTHEASTWARD INTO THE LOWER LAKES LATER TODAY BEFORE
SHIFTING EAST OF THE REGION TONIGHT. LOW-MID LEVEL FRONTOGENESIS IN
THE RIGHT ENTRANCE REGION OF 100KT+ 250MB JET IS ALREADY SUPPORTING
A BAND OF RAIN FROM EASTERN SD EAST INTO CENTRAL WISCONSIN. IN
ADDITION...SECOND AREA OF SHOWERS AND THUNDERSTORMS DEVELOPING OVER
IOWA IN ASSOCIATED WITH STRENGTHENING LOW LEVEL JET/WAA. THESE TWO
REGIONS OF PRECIP ARE LIKELY TO CONGEAL AND SPREAD ACROSS OUR CWA
LATER THIS MORNING AND CONTINUE INTO THE AFTERNOON. SOME WEAK
ELEVATED INSTABILITY COULD SUPPORT AN ISOLATED THUNDERSTORM SOUTH
BUT CHANCES AND AREAL COVERAGE OF THUNDER APPEAR LOW. AS TROUGH AXIS
TRANSLATE QUICKLY EASTWARD LOOK FOR RAIN/SHOWERS TO END...POSSIBLY
AS A PERIOD OF DRIZZLE LATER THIS AFTERNOON. TEMPS ARE TRICKY AND
WILL HINGE ON HOW MUCH THEY CAN RISE BEFORE RAIN STARTS AND THEY
LOSE A LITTLE GROUND THIS AFTERNOON.

STRONG SUBSIDENCE AND DRYING ARE FORECAST IN THE WAKE OF THE TROUGH
WHICH SHOULD LEAD TO RAPID CLEARING THIS EVENING WITH ANOTHER FAIRLY
HEALTHY PUSH OF EARLY SEASON COLD AIR ARRIVING TONIGHT. ONCE AGAIN
LOOKING FOR LOWS TO DROP INTO THE 30S OVER WESTERN PORTIONS OF THE
CWA...PARTICULARLY THE TYPICALLY FAVORED COOL SPOTS. CANT RULE OUT A
TOUCH OF FROST IN THE SHELTERED COOL SPOTS...ESPECIALLY ON ELEVATED
OBJECTS...BUT NOT EXPECTED TO BE A BIG ENOUGH DEAL TO INCLUDE IN
GRIDS.

TUESDAY LOOKS TO BE SUNNY AND UNSEASONABLY COOL...BUT NOT AS CHILLY
AS LAST WEEK. A SLOW BUT STEADY WARMING TREND WILL COMMENCE
WEDNESDAY AND CONTINUE INTO THE WEEKEND WITH HIGHS EVENTUALLY
REBOUNDING BACK TOWARD IF NOT A BIT ABOVE AVERAGE TOWARD THE
WEEKEND. NO RAIN IS EXPECTED THROUGH FRIDAY WITH PLENTY OF SUNSHINE
AND ALL AROUND PLEASANT WEATHER. MEDIUM RANGE MODELS DO SUGGEST
PATTERN COULD TURN POTENTIALLY STORMIER NEXT WEEKEND AS FLOW
FLATTENS OUT A BIT AND WARM AIR ADVECTION STRENGTHENS IN ADVANCE OF
TROUGH DIGGING INTO THE NORTHERN/CENTRAL PLAINS. STILL SOME
DISAGREEMENT IN THE DETAILS...NOT SURPRISINGLY THIS FAR OUT...SO
KEPT POPS MODEST FOR NOW UNTIL DETAILS CAN BE BETTER PINNED DOWN IN
THE COMING DAYS.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* WIND DIRECTION AND SPEEDS ASSOCIATED WITH FROPA THIS AFTERNOON
  ...NORTH-NORTHEAST WIND LOOKING LIKELY BY LATE AFTERNOON...WIND
  SPEEDS COULD REMAIN UNDER 10 KT.
* CIGS LOWERING TO MVFR WITH SHRA.

BMD/KB

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

A COLD FRONT STRETCHES ACROSS CENTRAL LAKE MICHIGAN INTO CENTRAL
IOWA EARLY THIS MORNING AND WILL SLOWLY SAG TOWARDS THE REGION
THROUGH THE DAY. OUT AHEAD...A FEW EARLY MORNING HIGH BASED SHOWERS
AND THUNDERSTORMS HAVE DEVELOPED ASSOCIATED WITH A MID LEVEL SPEED
MAX. MOST INTENSE ACTIVITY THUS FAR HAS MOSTLY BEEN FOCUSED SOUTH OF
THE TERMINALS THIS MORNING BUT THE AREA OF SHRA/TSRA MOVING INTO
NORTHWEST IL WILL ARRIVE AT THE TERMINALS OVER THE NEXT FEW HOURS.
THERE IS SOME VERY MODEST INSTABILITY WITH EQUILIBRIUM LEVELS DEEP
ENOUGH TO SUPPORT AT LEAST AN ISOLATED LIGHTNING THREAT BUT FOR NOW
LOW COVERAGE WOULD PRECLUDE MENTION OF TS IN TAF AND WILL MAINTAIN
SHRA. AS THE COLD FRONT SAGS SOUTH ACROSS THE TERMINALS LATER
TODAY...GUIDANCE HAS COME INTO BETTER AGREEMENT THAT THERE WILL BE A
WIND SHIFT TO THE N...POSSIBLY NNE...BEFORE WINDS SETTLE BACK TO A
NW DIRECTION LATER TODAY. THERE MAY BE A BRIEF UPTICK IN THE WINDS
MID AFTERNOON INTO THE 10-12KT RANGE. CIGS WILL ALSO DECREASE AS THE
FRONTAL TROUGH APPROACHES WITH THE POTENTIAL FOR SEVERAL HOURS OF
MVFR CIGS THIS AFTERNOON AND EARLY EVENING. DRIER AIR MOVING IN THIS
EVENING SHOULD ALLOW CIGS TO SCATTER OUT FOR TONIGHT WITH A RETURN
TO VFR CONDITIONS. WINDS ARE EXPECTED TO DIMINISH OVERNIGHT AND
DEPENDING ON HOW QUICKLY SKIES CLEAR WILL HAVE TO KEEP AN EYE ON THE
FOG POTENTIAL...ESPECIALLY AT RFD WITH FUTURE TAF UPDATES.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* MEDIUM TO HIGH CONFIDENCE IN WIND DIRECTION...LOW-MEDIUM THAT WINDS
  WILL GET AS HIGH AS 10 KT LATE THIS AFTERNOON.
* LOW-MEDIUM CONFIDENCE IN SHRA/MVFR TIMING.

BMD/KB

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

TUESDAY NIGHT THROUGH FRIDAY...PRIMARILY VFR.
SATURDAY THROUGH SUNDAY...PERIODIC CHANCES FOR THUNDERSTORMS.

BMD

&&

.MARINE...
303 AM CDT

LOW PRESSURE NEAR JAMES BAY THIS MORNING WILL DRAG A COLD FRONT
ACROSS LAKE MICHIGAN. WINDS WILL TURN NORTHWEST TO NORTH BEHIND THE
FRONT...AND MAY BRIEFLY INCREASE INTO THE 20 TO 25 KT RANGE
ESPECIALLY ON THE SOUTH END OF THE LAKE THIS EVENING. HIGH PRESSURE
WILL BUILD IN BEHIND THE FRONT ALLOWING WINDS TO REMAIN MODEST FOR A
PERIOD BEFORE SOUTHWEST FLOW BEGINS TO FRESHEN UP AGAIN OVER THE
NORTH HALF OF LAKE MICHIGAN MIDDAY TUESDAY. ANOTHER COLD FRONT WILL
DIVE SOUTH ACROSS LAKE MICHIGAN ON WEDNESDAY TURNING WINDS NORTH TO
NORTHEAST AND INCREASING FOR A SHORT PERIOD TO AROUND 30 KT ONCE
AGAIN.

BMD

&&

.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 151620
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1120 AM CDT MON SEP 15 2014

.DISCUSSION...
311 AM CDT

DISMAL AND SHOWERY WEATHER ON TAP TODAY FOLLOWED BY PRETTY
SPECTACULAR WEATHER THE REMAINDER OF THE WEEK.

FAIRLY ENERGETIC SHORTWAVE TROUGH OVER THE DAKOTAS THIS MORNING
WILL DIG SOUTHEASTWARD INTO THE LOWER LAKES LATER TODAY BEFORE
SHIFTING EAST OF THE REGION TONIGHT. LOW-MID LEVEL FRONTOGENESIS IN
THE RIGHT ENTRANCE REGION OF 100KT+ 250MB JET IS ALREADY SUPPORTING
A BAND OF RAIN FROM EASTERN SD EAST INTO CENTRAL WISCONSIN. IN
ADDITION...SECOND AREA OF SHOWERS AND THUNDERSTORMS DEVELOPING OVER
IOWA IN ASSOCIATED WITH STRENGTHENING LOW LEVEL JET/WAA. THESE TWO
REGIONS OF PRECIP ARE LIKELY TO CONGEAL AND SPREAD ACROSS OUR CWA
LATER THIS MORNING AND CONTINUE INTO THE AFTERNOON. SOME WEAK
ELEVATED INSTABILITY COULD SUPPORT AN ISOLATED THUNDERSTORM SOUTH
BUT CHANCES AND AREAL COVERAGE OF THUNDER APPEAR LOW. AS TROUGH AXIS
TRANSLATE QUICKLY EASTWARD LOOK FOR RAIN/SHOWERS TO END...POSSIBLY
AS A PERIOD OF DRIZZLE LATER THIS AFTERNOON. TEMPS ARE TRICKY AND
WILL HINGE ON HOW MUCH THEY CAN RISE BEFORE RAIN STARTS AND THEY
LOSE A LITTLE GROUND THIS AFTERNOON.

STRONG SUBSIDENCE AND DRYING ARE FORECAST IN THE WAKE OF THE TROUGH
WHICH SHOULD LEAD TO RAPID CLEARING THIS EVENING WITH ANOTHER FAIRLY
HEALTHY PUSH OF EARLY SEASON COLD AIR ARRIVING TONIGHT. ONCE AGAIN
LOOKING FOR LOWS TO DROP INTO THE 30S OVER WESTERN PORTIONS OF THE
CWA...PARTICULARLY THE TYPICALLY FAVORED COOL SPOTS. CANT RULE OUT A
TOUCH OF FROST IN THE SHELTERED COOL SPOTS...ESPECIALLY ON ELEVATED
OBJECTS...BUT NOT EXPECTED TO BE A BIG ENOUGH DEAL TO INCLUDE IN
GRIDS.

TUESDAY LOOKS TO BE SUNNY AND UNSEASONABLY COOL...BUT NOT AS CHILLY
AS LAST WEEK. A SLOW BUT STEADY WARMING TREND WILL COMMENCE
WEDNESDAY AND CONTINUE INTO THE WEEKEND WITH HIGHS EVENTUALLY
REBOUNDING BACK TOWARD IF NOT A BIT ABOVE AVERAGE TOWARD THE
WEEKEND. NO RAIN IS EXPECTED THROUGH FRIDAY WITH PLENTY OF SUNSHINE
AND ALL AROUND PLEASANT WEATHER. MEDIUM RANGE MODELS DO SUGGEST
PATTERN COULD TURN POTENTIALLY STORMIER NEXT WEEKEND AS FLOW
FLATTENS OUT A BIT AND WARM AIR ADVECTION STRENGTHENS IN ADVANCE OF
TROUGH DIGGING INTO THE NORTHERN/CENTRAL PLAINS. STILL SOME
DISAGREEMENT IN THE DETAILS...NOT SURPRISINGLY THIS FAR OUT...SO
KEPT POPS MODEST FOR NOW UNTIL DETAILS CAN BE BETTER PINNED DOWN IN
THE COMING DAYS.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* WIND DIRECTION AND SPEEDS ASSOCIATED WITH FROPA THIS AFTERNOON
  ...NORTH-NORTHEAST WIND LOOKING LIKELY BY LATE AFTERNOON...WIND
  SPEEDS COULD REMAIN UNDER 10 KT.
* CIGS LOWERING TO MVFR WITH SHRA.

BMD/KB

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

A COLD FRONT STRETCHES ACROSS CENTRAL LAKE MICHIGAN INTO CENTRAL
IOWA EARLY THIS MORNING AND WILL SLOWLY SAG TOWARDS THE REGION
THROUGH THE DAY. OUT AHEAD...A FEW EARLY MORNING HIGH BASED SHOWERS
AND THUNDERSTORMS HAVE DEVELOPED ASSOCIATED WITH A MID LEVEL SPEED
MAX. MOST INTENSE ACTIVITY THUS FAR HAS MOSTLY BEEN FOCUSED SOUTH OF
THE TERMINALS THIS MORNING BUT THE AREA OF SHRA/TSRA MOVING INTO
NORTHWEST IL WILL ARRIVE AT THE TERMINALS OVER THE NEXT FEW HOURS.
THERE IS SOME VERY MODEST INSTABILITY WITH EQUILIBRIUM LEVELS DEEP
ENOUGH TO SUPPORT AT LEAST AN ISOLATED LIGHTNING THREAT BUT FOR NOW
LOW COVERAGE WOULD PRECLUDE MENTION OF TS IN TAF AND WILL MAINTAIN
SHRA. AS THE COLD FRONT SAGS SOUTH ACROSS THE TERMINALS LATER
TODAY...GUIDANCE HAS COME INTO BETTER AGREEMENT THAT THERE WILL BE A
WIND SHIFT TO THE N...POSSIBLY NNE...BEFORE WINDS SETTLE BACK TO A
NW DIRECTION LATER TODAY. THERE MAY BE A BRIEF UPTICK IN THE WINDS
MID AFTERNOON INTO THE 10-12KT RANGE. CIGS WILL ALSO DECREASE AS THE
FRONTAL TROUGH APPROACHES WITH THE POTENTIAL FOR SEVERAL HOURS OF
MVFR CIGS THIS AFTERNOON AND EARLY EVENING. DRIER AIR MOVING IN THIS
EVENING SHOULD ALLOW CIGS TO SCATTER OUT FOR TONIGHT WITH A RETURN
TO VFR CONDITIONS. WINDS ARE EXPECTED TO DIMINISH OVERNIGHT AND
DEPENDING ON HOW QUICKLY SKIES CLEAR WILL HAVE TO KEEP AN EYE ON THE
FOG POTENTIAL...ESPECIALLY AT RFD WITH FUTURE TAF UPDATES.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* MEDIUM TO HIGH CONFIDENCE IN WIND DIRECTION...LOW-MEDIUM THAT WINDS
  WILL GET AS HIGH AS 10 KT LATE THIS AFTERNOON.
* LOW-MEDIUM CONFIDENCE IN SHRA/MVFR TIMING.

BMD/KB

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

TUESDAY NIGHT THROUGH FRIDAY...PRIMARILY VFR.
SATURDAY THROUGH SUNDAY...PERIODIC CHANCES FOR THUNDERSTORMS.

BMD

&&

.MARINE...
303 AM CDT

LOW PRESSURE NEAR JAMES BAY THIS MORNING WILL DRAG A COLD FRONT
ACROSS LAKE MICHIGAN. WINDS WILL TURN NORTHWEST TO NORTH BEHIND THE
FRONT...AND MAY BRIEFLY INCREASE INTO THE 20 TO 25 KT RANGE
ESPECIALLY ON THE SOUTH END OF THE LAKE THIS EVENING. HIGH PRESSURE
WILL BUILD IN BEHIND THE FRONT ALLOWING WINDS TO REMAIN MODEST FOR A
PERIOD BEFORE SOUTHWEST FLOW BEGINS TO FRESHEN UP AGAIN OVER THE
NORTH HALF OF LAKE MICHIGAN MIDDAY TUESDAY. ANOTHER COLD FRONT WILL
DIVE SOUTH ACROSS LAKE MICHIGAN ON WEDNESDAY TURNING WINDS NORTH TO
NORTHEAST AND INCREASING FOR A SHORT PERIOD TO AROUND 30 KT ONCE
AGAIN.

BMD

&&

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

$$

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000
FXUS63 KLOT 151620
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1120 AM CDT MON SEP 15 2014

.DISCUSSION...
311 AM CDT

DISMAL AND SHOWERY WEATHER ON TAP TODAY FOLLOWED BY PRETTY
SPECTACULAR WEATHER THE REMAINDER OF THE WEEK.

FAIRLY ENERGETIC SHORTWAVE TROUGH OVER THE DAKOTAS THIS MORNING
WILL DIG SOUTHEASTWARD INTO THE LOWER LAKES LATER TODAY BEFORE
SHIFTING EAST OF THE REGION TONIGHT. LOW-MID LEVEL FRONTOGENESIS IN
THE RIGHT ENTRANCE REGION OF 100KT+ 250MB JET IS ALREADY SUPPORTING
A BAND OF RAIN FROM EASTERN SD EAST INTO CENTRAL WISCONSIN. IN
ADDITION...SECOND AREA OF SHOWERS AND THUNDERSTORMS DEVELOPING OVER
IOWA IN ASSOCIATED WITH STRENGTHENING LOW LEVEL JET/WAA. THESE TWO
REGIONS OF PRECIP ARE LIKELY TO CONGEAL AND SPREAD ACROSS OUR CWA
LATER THIS MORNING AND CONTINUE INTO THE AFTERNOON. SOME WEAK
ELEVATED INSTABILITY COULD SUPPORT AN ISOLATED THUNDERSTORM SOUTH
BUT CHANCES AND AREAL COVERAGE OF THUNDER APPEAR LOW. AS TROUGH AXIS
TRANSLATE QUICKLY EASTWARD LOOK FOR RAIN/SHOWERS TO END...POSSIBLY
AS A PERIOD OF DRIZZLE LATER THIS AFTERNOON. TEMPS ARE TRICKY AND
WILL HINGE ON HOW MUCH THEY CAN RISE BEFORE RAIN STARTS AND THEY
LOSE A LITTLE GROUND THIS AFTERNOON.

STRONG SUBSIDENCE AND DRYING ARE FORECAST IN THE WAKE OF THE TROUGH
WHICH SHOULD LEAD TO RAPID CLEARING THIS EVENING WITH ANOTHER FAIRLY
HEALTHY PUSH OF EARLY SEASON COLD AIR ARRIVING TONIGHT. ONCE AGAIN
LOOKING FOR LOWS TO DROP INTO THE 30S OVER WESTERN PORTIONS OF THE
CWA...PARTICULARLY THE TYPICALLY FAVORED COOL SPOTS. CANT RULE OUT A
TOUCH OF FROST IN THE SHELTERED COOL SPOTS...ESPECIALLY ON ELEVATED
OBJECTS...BUT NOT EXPECTED TO BE A BIG ENOUGH DEAL TO INCLUDE IN
GRIDS.

TUESDAY LOOKS TO BE SUNNY AND UNSEASONABLY COOL...BUT NOT AS CHILLY
AS LAST WEEK. A SLOW BUT STEADY WARMING TREND WILL COMMENCE
WEDNESDAY AND CONTINUE INTO THE WEEKEND WITH HIGHS EVENTUALLY
REBOUNDING BACK TOWARD IF NOT A BIT ABOVE AVERAGE TOWARD THE
WEEKEND. NO RAIN IS EXPECTED THROUGH FRIDAY WITH PLENTY OF SUNSHINE
AND ALL AROUND PLEASANT WEATHER. MEDIUM RANGE MODELS DO SUGGEST
PATTERN COULD TURN POTENTIALLY STORMIER NEXT WEEKEND AS FLOW
FLATTENS OUT A BIT AND WARM AIR ADVECTION STRENGTHENS IN ADVANCE OF
TROUGH DIGGING INTO THE NORTHERN/CENTRAL PLAINS. STILL SOME
DISAGREEMENT IN THE DETAILS...NOT SURPRISINGLY THIS FAR OUT...SO
KEPT POPS MODEST FOR NOW UNTIL DETAILS CAN BE BETTER PINNED DOWN IN
THE COMING DAYS.

IZZI

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* WIND DIRECTION AND SPEEDS ASSOCIATED WITH FROPA THIS AFTERNOON
  ...NORTH-NORTHEAST WIND LOOKING LIKELY BY LATE AFTERNOON...WIND
  SPEEDS COULD REMAIN UNDER 10 KT.
* CIGS LOWERING TO MVFR WITH SHRA.

BMD/KB

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

A COLD FRONT STRETCHES ACROSS CENTRAL LAKE MICHIGAN INTO CENTRAL
IOWA EARLY THIS MORNING AND WILL SLOWLY SAG TOWARDS THE REGION
THROUGH THE DAY. OUT AHEAD...A FEW EARLY MORNING HIGH BASED SHOWERS
AND THUNDERSTORMS HAVE DEVELOPED ASSOCIATED WITH A MID LEVEL SPEED
MAX. MOST INTENSE ACTIVITY THUS FAR HAS MOSTLY BEEN FOCUSED SOUTH OF
THE TERMINALS THIS MORNING BUT THE AREA OF SHRA/TSRA MOVING INTO
NORTHWEST IL WILL ARRIVE AT THE TERMINALS OVER THE NEXT FEW HOURS.
THERE IS SOME VERY MODEST INSTABILITY WITH EQUILIBRIUM LEVELS DEEP
ENOUGH TO SUPPORT AT LEAST AN ISOLATED LIGHTNING THREAT BUT FOR NOW
LOW COVERAGE WOULD PRECLUDE MENTION OF TS IN TAF AND WILL MAINTAIN
SHRA. AS THE COLD FRONT SAGS SOUTH ACROSS THE TERMINALS LATER
TODAY...GUIDANCE HAS COME INTO BETTER AGREEMENT THAT THERE WILL BE A
WIND SHIFT TO THE N...POSSIBLY NNE...BEFORE WINDS SETTLE BACK TO A
NW DIRECTION LATER TODAY. THERE MAY BE A BRIEF UPTICK IN THE WINDS
MID AFTERNOON INTO THE 10-12KT RANGE. CIGS WILL ALSO DECREASE AS THE
FRONTAL TROUGH APPROACHES WITH THE POTENTIAL FOR SEVERAL HOURS OF
MVFR CIGS THIS AFTERNOON AND EARLY EVENING. DRIER AIR MOVING IN THIS
EVENING SHOULD ALLOW CIGS TO SCATTER OUT FOR TONIGHT WITH A RETURN
TO VFR CONDITIONS. WINDS ARE EXPECTED TO DIMINISH OVERNIGHT AND
DEPENDING ON HOW QUICKLY SKIES CLEAR WILL HAVE TO KEEP AN EYE ON THE
FOG POTENTIAL...ESPECIALLY AT RFD WITH FUTURE TAF UPDATES.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* MEDIUM TO HIGH CONFIDENCE IN WIND DIRECTION...LOW-MEDIUM THAT WINDS
  WILL GET AS HIGH AS 10 KT LATE THIS AFTERNOON.
* LOW-MEDIUM CONFIDENCE IN SHRA/MVFR TIMING.

BMD/KB

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

TUESDAY NIGHT THROUGH FRIDAY...PRIMARILY VFR.
SATURDAY THROUGH SUNDAY...PERIODIC CHANCES FOR THUNDERSTORMS.

BMD

&&

.MARINE...
303 AM CDT

LOW PRESSURE NEAR JAMES BAY THIS MORNING WILL DRAG A COLD FRONT
ACROSS LAKE MICHIGAN. WINDS WILL TURN NORTHWEST TO NORTH BEHIND THE
FRONT...AND MAY BRIEFLY INCREASE INTO THE 20 TO 25 KT RANGE
ESPECIALLY ON THE SOUTH END OF THE LAKE THIS EVENING. HIGH PRESSURE
WILL BUILD IN BEHIND THE FRONT ALLOWING WINDS TO REMAIN MODEST FOR A
PERIOD BEFORE SOUTHWEST FLOW BEGINS TO FRESHEN UP AGAIN OVER THE
NORTH HALF OF LAKE MICHIGAN MIDDAY TUESDAY. ANOTHER COLD FRONT WILL
DIVE SOUTH ACROSS LAKE MICHIGAN ON WEDNESDAY TURNING WINDS NORTH TO
NORTHEAST AND INCREASING FOR A SHORT PERIOD TO AROUND 30 KT ONCE
AGAIN.

BMD

&&

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

$$

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