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000
FXUS63 KLOT 010604
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
104 AM CDT SAT NOV 1 2014

.UPDATE...
958 PM CDT

COVERAGE AND INTENSITY OF THE LAKE EFFECT PRECIP IS
DIMINISHING...WHILE A WINTRY MIX IS STILL BEING OBSERVED. LOW
LEVEL VEERING WILL CONTINUE WITH THE BULK OF THIS PRECIP SHIFTING
MORE INTO NORTHEAST ILLINOIS OVER THE NEXT COUPLE OF HOURS. STILL
ANTICIPATE A TREND TOWARDS ALL SNOW IN THE NEAR TERM EVEN FOR
AREAS IMMEDIATELY NEAR THE LAKE...BUT DO EXPECT A CONTINUED
DIMINISHING TREND AS WELL DURING THIS TIME. IN THE NEAR
TERM...BRIEF REDUCTIONS IN VISIBILITY AND MINOR ACCUMULATIONS
MAINLY ON GRASSY SURFACES ARE STILL POSSIBLE UNDER THE MORE
INTENSE SNOWFALL.

RODRIGUEZ

&&

.SHORT TERM...
307 PM CDT

THROUGH TONIGHT...

NO CHANGES PLANNED WITH HEADLINES.

SEVERAL BANDS OF LAKE EFFECT SNOW HAVE DEVELOPED ACROSS SOUTHERN
LAKE MICHIGAN EARLY THIS AFTERNOON...WITH SOME OF THESE SNOW SHOWERS
IMPACTING PORTIONS OF THE NORTHEASTERN ILLINOIS SHORES.
HOWEVER...THE MOST SUBSTANTIAL AREA OF LAKE EFFECT RAIN AND SNOW HAS
BEEN OCCURRING ALONG THE SOUTHERN TIP OF LAKE MICHIGAN AND ACROSS THE
ADVISORY AREA OF NORTHWESTERN INDIANA. BASED ON NUMEROUS PHONE
CALLS ACROSS THIS AREA IT APPEARS AREAS NEAR THE LAKE ARE SLIGHTLY
WARMER...RESULTING IN A RAIN SNOW MIX. HOWEVER...AREAS ROUGHLY 20 TO
30 MILES INLAND (BASICALLY ALONG AND SOUTH OF A CROWN POINT TO
VALPARAISO INDIANA LINE) THE PRECIPITATION IS MAINLY IN THE FORM OF
SNOW. SEVERAL REPORTS OF ACCUMULATING SNOW HAVE BEEN RECEIVED SOUTH
OF THIS LINE...WITH LOW VISIBILITIES UNDER A MILE.

BASED ON CURRENT RADAR TRENDS AND SHORT RANGE HIRES GUIDANCE...IT
APPEARS THIS ACTIVITY WILL CONTINUE TO BE FOCUSED MAINLY ACROSS
NORTHWESTERN INDIANA FOR THE NEXT FEW HOURS...THROUGH LATE
AFTERNOON/EARLY THIS EVENING. HOWEVER...SOME OF THE LESS ORGANIZED LAKE
EFFECT SNOW SHOWERS WILL LIKELY IMPACT PORTIONS OF COOK AND LAKE
COUNTIES IN ILLINOIS AS WELL DURING THIS TIME. FINALLY...AS THE
SURFACE LOW SHIFTS SOUTHEAST OVER THE OHIO VALLEY INTO THIS EVENING
THE BOUNDARY LAYER FLOW WILL VEER AND WEAKEN A BIT. THIS SHOULD
ALLOW THE BETTER FOCUS FOR LAKE EFFECT SHOWERS TO SHIFT FARTHER WEST
ACROSS PORTIONS OF EASTERN ILLINOIS...INCLUDING THE CHICAGO METRO
AREA NEAR THE LAKE. WHILE THERE COULD BE A SHORT PERIOD OF SOME
MODERATE...OR EVEN BRIEFLY HEAVY SNOW SHOWERS INTO NORTHEASTERN
ILLINOIS INTO THIS EVENING...I HAVE CHOSEN NOT TO EXTEND THE WINTER
ADVISORIES FARTHER WEST INTO ILLINOIS. THIS IS MAINLY DUE TO THE
FACT THAT IT APPEARS THE THREAT FOR BETTER MORE ORGANIZED LAKE
EFFECT SNOW WILL BE OF SHORT DURATION...LIMITING OVERALL
ACCUMULATIONS. HEIGHT RISES AND WARMING TEMPERATURES IN THE MID
LEVELS SHOULD ALLOW INVERSION HEIGHTS TO DROP BELOW THE DENDRITIC
GROWTH ZONE BY LATER THIS EVENING/OVERNIGHT. THE MODELS HAVE BEEN
INSISTENT ON THIS FOR THE PAST FEW DAYS AND SEE NO REASON WHY THIS
WOULD NOT OCCUR AS THE UPPER RIDGE TO OUR WEST BEGINS TO BUILD
EASTWARD. THEREFORE...ANY LEFT OVER LAKE EFFECT SNOW SHOWERS WILL
LIKELY NOT BE EFFICIENT SNOWFALL PRODUCERS AND LIKELY BE LOOSELY
ORGANIZED...AND HENCE THE THREAT FOR ACCUMULATING SNOWFALL SHOULD
COME TO AN END BY LATER THIS EVENING.

THE WINDS WITH THIS SYSTEM HAVE BEEN IMPRESSIVE. KGYY HAS BEEN
EXPERIENCING GUSTS TO 58 KT FOR SEVERAL HOURS...WITH SIMILAR
MAGNITUDES NOTED ALONG THE LAKE SHORE. IT APPEARS THESE STRONG WINDS
WILL SLOWLY EASE TONIGHT AS THE SURFACE HIGH OVERSPREADS THE AREA ON
SATURDAY. THEREFORE...NO CHANGES ARE PLANNED WITH THE CURRENT WIND
ADVISORIES OR WARNINGS.

LAKE SHORE FLOODING CONTINUES TO BE AN ISSUE...ESPECIALLY IN
CHICAGO...WHERE WAVES HAVE BEEN GETTING WATER ONTO LAKE SHORE DRIVE.
WE CONSIDERED TO UPGRADE TO A LAKE SHORE FLOOD WARNING...BUT DECIDED
TO JUST BEEF UP THE WORDING IN THE CURRENT ADVISORY AS A WARNING
WOULD NOT DUE MUCH GOOD AT THIS STAGE OF THE GAME.

KJB

&&

.LONG TERM...
307 PM CDT

TOMORROW THROUGH THURSDAY...

SATURDAY AND SUNDAY...
THE UPPER LEVEL TROUGH PUSHES EAST ALLOWING A LARGE UPPER LEVEL
RIDGE TO MOVE OVERHEAD THROUGH THE WEEKEND. THE CORRESPONDING
SURFACE HIGH MOVES OVER THE REGION TOMORROW EVENING.

GUIDANCE CONTINUES TO FEATURE A NARROW CONVERGENCE BAND ALONG THE
SOUTHWEST END OF LAKE MICHIGAN EARLY SATURDAY MORNING.  KEPT A
SLIGHT CHANCE OF PRECIP IN FOR FAR NORTHEAST IL WITH THE BAND
DISSIPATING BY LATE MORNING/EARLY AFTERNOON AS FORCING AND MOISTURE
WEAKEN. NOT EXPECTING ANY ADDITIONAL SIGNIFICANT ACCUMULATION AND
THE PRECIP TYPE WILL BE A SNOW/RAIN MIX AS TEMPERATURES WILL BE
ABOVE FREEZING OVER THE LAKE.  HAVE MEDIUM CONFIDENCE IN THE BAND
PERSISTING UNTIL MORNING...MEDIUM HIGH CONFIDENCE IN THE BAND MAINLY
IMPACTING THE IL SIDE OF THE LAKE...AND HIGH CONFIDENCE IN LITTLE TO
NO ADDITIONAL ACCUMULATION.

WINDS DECREASE SATURDAY AS THE HIGH MOVES OVERHEAD.  WARMER AIR
BEGINS TO MOVE IN AS WELL WITH HIGHS IN THE LOW 40S TOMORROW. WINDS
TURN SOUTH BEHIND THE HIGH SUNDAY AND USHER IN EVEN WARMER AIR WITH
HIGHS IN THE UPPER 40S TO AROUND 50. SATURDAY AFTERNOON THROUGH
SUNDAY NIGHT WILL BE DRY.

MONDAY THROUGH THURSDAY...
THE RIDGE AXIS MOVES OVERHEAD MONDAY AS THE SURFACE LOW SLIDES OVER
THE SE U.S. THE WARM-UP CONTINUES WITH HIGHS IN THE UPPER 50S TO
AROUND 60 MONDAY...AND MID 50S EXPECTED THROUGH MID WEEK. OVERNIGHT
LOWS VARY FROM THE MID 40S MONDAY NIGHT TO THE MID TO LOWER 30S
THURSDAY NIGHT.

A SURFACE LOW MOVES INTO ONTARIO TUESDAY...AND IT DRAGS A COLD FRONT
ACROSS THE REGION TUESDAY. EXPECTING WIDESPREAD SHOWERS TUESDAY
MORNING WITH RAIN ENDING FROM WEST TO EAST AS THE FRONT SLIDES EAST
TUESDAY EVENING/NIGHT.  GUIDANCE DIFFERS ON HOW MUCH PRECIP WILL
FALL...BUT ITS LOOKING LIKE A GOOD WETTING RAIN IS EXPECTED.

A WEAKER LOW PASSES JUST TO OUR NORTH MID WEEK AND HAVE MEDIUM-LOW
CONFIDENCE IN PRECIP MAKING IT INTO NORTHERN IL WEDNESDAY. THINKING
PRECIP WILL REMAIN CLOSELY TIED TO THE LOW WHICH RIGHT NOW WILL BE
OVER SOUTHERN WI. IF THE LOW/S TRACK WERE TO DIP A BIT MORE
SOUTH...THERE WOULD BE A BETTER CHANCE FOR PRECIP ACROSS FAR
NORTHERN IL.

WINDS TURN NORTHWEST BEHIND THE LOW AND ANOTHER LAKE EFFECT PRECIP
SITUATION IS POSSIBLE FOR NW INDIANA WEDNESDAY NIGHT. ONLY HAVE RAIN
FOR NOW AS TEMPS WILL BE ABOVE FREEZING.  WINDS REMAIN OFF OF THE
LAKE THROUGH THURSDAY NIGHT AS ANOTHER HIGH PRESSURE SYSTEM
APPROACHES FROM THE WEST.

JEE

&&

.AVIATION...

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

* NORTH WINDS GUSTING 20-25 KT GRADUALLY DIMINISH OVERNIGHT.

* PERIODIC LIGHT SNOW SHOWERS OVERNIGHT WITH LITTLE IF ANY
  VISIBILITY REDUCTION.

* VFR CIGS EXPECTED TO PREVAIL BUT SOME MVFR LEVEL CLOUDS MAY
  DEVELOP OVERNIGHT. LOWERING TO MVFR POSSIBLE TOWARD DAYBREAK
  THEN LIFT AND SCATTER TO VFR LATE AFTERNOON.

MDB

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

HIGH PRESSURE CONTINUES TO APPROACH FROM THE WEST WHICH IS HELPING
NORTH WINDS TO SLOWLY DIMINISH ACROSS NORTHERN ILLINOIS AWAY FROM
THE LAKE. NORTHWEST INDIANA CONTINUES TO SEE HIGHER GUSTS AND
ALTHOUGH GYY HAS NOT REPORTED SUSPECT GUSTS AROUND 40 KT ARE
CONTINUING. THESE GUSTS WILL EASE OVERNIGHT AS WELL BUT WILL
PROBABLY REMAIN UP NEAR 30 KT. LAKE EFFECT SNOW BANDS HAVE WANED
OVER THE PAST FEW HOURS BUT WILL LIKELY SEE CONTINUED LIGHT SNOW
SHOWERS AT ORD/MDW/GYY BUT AT THIS POINT SEE LITTLE IN THE WAY OF
VSBY REDUCTION. THESE SHOULD COME TO AN END LATER THIS MORNING.
CIGS REMAIN MAINLY VFR BUT CANNOT RULE OUT SOME MVFR PATCHES. CIGS
MAY LOWER TO MVFR TOWARD DAYBREAK BUT THIS COULD END UP BEING A
LITTLE PESSIMISTIC.

NORTH TO NORTHEAST WINDS WILL GUST TO NEAR 20 KT DURING THE DAY
TODAY ACROSS NORTHEAST IL AND NW INDIANA WITH FEW GUSTS ACROSS
NORTH-CENTRAL ILLINOIS. ANY MVFR WILL GRADUALLY LIFT TO VFR WITH
SCATTERING FROM WEST TO EAST. HIGH PRESSURE WILL MOVE OVERHEAD
TONIGHT ALLOWING WINDS TO DROP OFF WITH SUNSET THIS EVENING.

MDB


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

* HIGH CONFIDENCE IN WIND TRENDS.

* HIGH CONFIDENCE IN -SHSN PERSISTING OVERNIGHT WITH MINIMAL VSBY
  REDUCTION.

* MEDIUM-HIGH CONFIDENCE IN CIG TRENDS THROUGH SATURDAY MORNING.
  MEDIUM CONFIDENCE IN DURATION OF MVFR CIGS INTO THE AFTERNOON.

MDB

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

SUNDAY...DRY/VFR. SOUTH WINDS 10-15 KT.

MONDAY...DRY/VFR DURING THE DAY. SHRA LIKELY MONDAY NIGHT. GUSTY
SOUTHWEST WINDS 15-20 KT.

TUESDAY...SHRA/MVFR LIKELY. SOUTHWEST WINDS.

WEDNESDAY...DRY/VFR. SOUTHWEST WINDS.

THURSDAY...DRY/VFR. WEST-NORTHWEST WINDS.

RATZER

&&

.MARINE...
212 PM CDT

STORM FORCE WINDS WILL SLOWLY EASE TO GALES TONIGHT. NO CHANGES
PLANNED TO CURRENT HEADLINES.

FOR THE NEARSHORE ZONES...WILL NEED A PROLONGED SMALL CRAFT ADVISORY
THROUGH AT LEAST SATURDAY AS VERY LARGE WAVES SUBSIDE.  MAY FLIRT
WITH SMALL CRAFT ADVISORY CRITERIA WINDS AND WAVES SUNDAY AND
MONDAY. HAVE MEDIUM CONFIDENCE AS CONDITIONS MAY BE MARGINAL.

NORTH TO NORTHEAST WINDS TO 30 KT SLOWLY DIMINISH SATURDAY AND WINDS
TURN SOUTHWEST BEHIND A HIGH PRESSURE SYSTEM SUNDAY MORNING.  SOUTH
TO SOUTHWEST WINDS INCREASE TO 30 KT SUNDAY AFTERNOON AS THE
GRADIENT TIGHTENS BETWEEN THE DEPARTING HIGH AND AN APPROACHING
LOW.  SOUTH TO SOUTHWEST WINDS FINALLY DIMINISH TO UNDER 30 KT
MONDAY NIGHT...AND THEN WINDS TURN WEST 10-20 KT BEHIND THE LOWS
COLD FRONT TUESDAY. WEST WINDS INCREASE TO 20-25 KT AND BECOME
NORTHWEST WEDNESDAY NIGHT...AND MAY SEE 30 KT WINDS OVER THE
NORTHERN HALF OF THE LAKE THURSDAY.  WINDS DIMINISH THURSDAY NIGHT
AS HIGH PRESSURE MOVES OVER THE AREA.

KJB/JEE

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...LAKESHORE FLOOD ADVISORY...ILZ014 UNTIL 4 AM SATURDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002 UNTIL 4 AM SATURDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-
     LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 4 AM
     SATURDAY.

&&

$$

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

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





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000
FXUS63 KILX 010418
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1118 PM CDT Fri Oct 31 2014

.UPDATE...
ISSUED AT 825 PM CDT FRI OCT 31 2014

Lake moisuture continues to stream south-southwest into our area
this evening affecting areas mainly along and east of the I-55
corridor. Broad cyclonic flow forecast to continue thru the
early morning hours with the past several runs of the HRRR
indicating the band of moisture will be shrinking and affecting
areas of east central thru southeast Illinois overnight. Still
could see some scattered flurries over extreme eastern IL thru
midnight before the better setup for flurries shifts into west
central Indiana. Forecast has these trends well in hand this
evening so other than some minor adjustments to the sky cover
for this evening, no other changes were made to the grids. No
evening ZFP update will be needed.

Will freshen up the wording in our NPW product and have that out
by 845 pm.

&&

.SHORT TERM...(Tonight)
ISSUED AT 304 PM CDT FRI OCT 31 2014

Increased pressure gradient behind the cold front has created a
blustery day across Central Illinois.  In combination with colder
air moving into the region, wind chills are dropping in the 30s.
Although the winds are expected to slowly decrease after sunset...it
will be very slow and accompanied by dropping temperatures as well.
As a result, going into Halloween night, trick or treaters will
encounter temperatures in the upper 30s and lower 40s...with winds
still in the 20 to 25 mph range and occasionally very gusty early.
Wind chills at or below freezing for the few hours around sunset.
Temperatures tonight will drop mainly into the 20s and provide a
significant hard freeze for the end of October.  Though there is
some spread in the MOS for this event, vast majority keep the 20s in
place.  Some remaining lake effect snow/rain will dwindle into the
overnight hours, mainly impacting the extreme eastern IL/IN border
with flurries and light rain.  Accumulations are not expected.

&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 304 PM CDT FRI OCT 31 2014

Cold high pressure will settle over Illinois during the day Saturday
bringing much lighter winds, continuing through Saturday night. The
light winds and dry air mass will allow for another night of sub
freezing temperatures due to good radiational cooling. Temperatures
will moderate somewhat Sunday, but still remain much below average
with highs mainly in the upper 40s.

More unsettled weather is on track Monday to Wednesday as moist
southwesterly flow develops ahead of a strong upper level trough
digging into the southern Rockies. A frontal boundary will set up
from the southern Plains NE into the Ohio river valley Monday night
through Wed to bring chances for showers, especially Monday night
and Tuesday. Milder temperatures can be expected in this time
period, with highs in the upper 50s and lows mainly in the 40s.
Model data indicates weak instability with this system, meaning
thunderstorms are unlikely. Drier weather is expected Wed night thru
Friday as dry west northwesterly flow trails the system. Expect
seasonable highs generally in the mid to upper 50s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
ISSUED AT 1110 PM CDT FRI OCT 31 2014

VFR conditions are expected across most of the area this forecast
period. Will need to keep an eye on KCMI as forecast soundings
indicate they will be on the edge of some low VFR cigs with some
tempo MVFR cigs streaming south off of Lake Michigan thru sunrise
Saturday. 250 meter winds off local VAD wind profilers continues
to show a north to northeast flow off of Lake Michigan so the
bands of clouds tracking S-SW will occasionally get into parts
of our area, mainly along and east of the I-55 corridor. Once
the large area of high pressure to our northwest settles closer
to our area, boundary layer winds will shift enough to shunt the
lake moisture more into Indiana Saturday morning. Northerly
surface winds have been slowly decreasing this evening and expect
that trend to continue overnight. With the area of high pressure
pushing into central Illinois later Saturday, winds will be much
lighter from a north to northeast direction, but still average
from 10 to 15 kts with a few afternoon gusts up to 20 kts,
especially across the east.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING until 9 AM CDT Saturday FOR ILZ027>031-036>038-
040>057-061>063-066>068-071>073.

&&

$$

UPDATE...Smith
SHORT TERM...HJS
LONG TERM...Onton
AVIATION...Smith





000
FXUS63 KLOT 010306
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1006 PM CDT FRI OCT 31 2014

.UPDATE...
958 PM CDT

COVERAGE AND INTENSITY OF THE LAKE EFFECT PRECIP IS
DIMINISHING...WHILE A WINTRY MIX IS STILL BEING OBSERVED. LOW
LEVEL VEERING WILL CONTINUE WITH THE BULK OF THIS PRECIP SHIFTING
MORE INTO NORTHEAST ILLINOIS OVER THE NEXT COUPLE OF HOURS. STILL
ANTICIPATE A TREND TOWARDS ALL SNOW IN THE NEAR TERM EVEN FOR
AREAS IMMEDIATELY NEAR THE LAKE...BUT DO EXPECT A CONTINUED
DIMINISHING TREND AS WELL DURING THIS TIME. IN THE NEAR
TERM...BRIEF REDUCTIONS IN VISIBILITY AND MINOR ACCUMULATIONS
MAINLY ON GRASSY SURFACES ARE STILL POSSIBLE UNDER THE MORE
INTENSE SNOWFALL.

RODRIGUEZ

&&

.SHORT TERM...
307 PM CDT

THROUGH TONIGHT...

NO CHANGES PLANNED WITH HEADLINES.

SEVERAL BANDS OF LAKE EFFECT SNOW HAVE DEVELOPED ACROSS SOUTHERN
LAKE MICHIGAN EARLY THIS AFTERNOON...WITH SOME OF THESE SNOW SHOWERS
IMPACTING PORTIONS OF THE NORTHEASTERN ILLINOIS SHORES.
HOWEVER...THE MOST SUBSTANTIAL AREA OF LAKE EFFECT RAIN AND SNOW HAS
BEEN OCCURRING ALONG THE SOUTHERN TIP OF LAKE MICHIGAN AND ACROSS THE
ADVISORY AREA OF NORTHWESTERN INDIANA. BASED ON NUMEROUS PHONE
CALLS ACROSS THIS AREA IT APPEARS AREAS NEAR THE LAKE ARE SLIGHTLY
WARMER...RESULTING IN A RAIN SNOW MIX. HOWEVER...AREAS ROUGHLY 20 TO
30 MILES INLAND (BASICALLY ALONG AND SOUTH OF A CROWN POINT TO
VALPARAISO INDIANA LINE) THE PRECIPITATION IS MAINLY IN THE FORM OF
SNOW. SEVERAL REPORTS OF ACCUMULATING SNOW HAVE BEEN RECEIVED SOUTH
OF THIS LINE...WITH LOW VISIBILITIES UNDER A MILE.

BASED ON CURRENT RADAR TRENDS AND SHORT RANGE HIRES GUIDANCE...IT
APPEARS THIS ACTIVITY WILL CONTINUE TO BE FOCUSED MAINLY ACROSS
NORTHWESTERN INDIANA FOR THE NEXT FEW HOURS...THROUGH LATE
AFTERNOON/EARLY THIS EVENING. HOWEVER...SOME OF THE LESS ORGANIZED LAKE
EFFECT SNOW SHOWERS WILL LIKELY IMPACT PORTIONS OF COOK AND LAKE
COUNTIES IN ILLINOIS AS WELL DURING THIS TIME. FINALLY...AS THE
SURFACE LOW SHIFTS SOUTHEAST OVER THE OHIO VALLEY INTO THIS EVENING
THE BOUNDARY LAYER FLOW WILL VEER AND WEAKEN A BIT. THIS SHOULD
ALLOW THE BETTER FOCUS FOR LAKE EFFECT SHOWERS TO SHIFT FARTHER WEST
ACROSS PORTIONS OF EASTERN ILLINOIS...INCLUDING THE CHICAGO METRO
AREA NEAR THE LAKE. WHILE THERE COULD BE A SHORT PERIOD OF SOME
MODERATE...OR EVEN BRIEFLY HEAVY SNOW SHOWERS INTO NORTHEASTERN
ILLINOIS INTO THIS EVENING...I HAVE CHOSEN NOT TO EXTEND THE WINTER
ADVISORIES FARTHER WEST INTO ILLINOIS. THIS IS MAINLY DUE TO THE
FACT THAT IT APPEARS THE THREAT FOR BETTER MORE ORGANIZED LAKE
EFFECT SNOW WILL BE OF SHORT DURATION...LIMITING OVERALL
ACCUMULATIONS. HEIGHT RISES AND WARMING TEMPERATURES IN THE MID
LEVELS SHOULD ALLOW INVERSION HEIGHTS TO DROP BELOW THE DENDRITIC
GROWTH ZONE BY LATER THIS EVENING/OVERNIGHT. THE MODELS HAVE BEEN
INSISTENT ON THIS FOR THE PAST FEW DAYS AND SEE NO REASON WHY THIS
WOULD NOT OCCUR AS THE UPPER RIDGE TO OUR WEST BEGINS TO BUILD
EASTWARD. THEREFORE...ANY LEFT OVER LAKE EFFECT SNOW SHOWERS WILL
LIKELY NOT BE EFFICIENT SNOWFALL PRODUCERS AND LIKELY BE LOOSELY
ORGANIZED...AND HENCE THE THREAT FOR ACCUMULATING SNOWFALL SHOULD
COME TO AN END BY LATER THIS EVENING.

THE WINDS WITH THIS SYSTEM HAVE BEEN IMPRESSIVE. KGYY HAS BEEN
EXPERIENCING GUSTS TO 58 KT FOR SEVERAL HOURS...WITH SIMILAR
MAGNITUDES NOTED ALONG THE LAKE SHORE. IT APPEARS THESE STRONG WINDS
WILL SLOWLY EASE TONIGHT AS THE SURFACE HIGH OVERSPREADS THE AREA ON
SATURDAY. THEREFORE...NO CHANGES ARE PLANNED WITH THE CURRENT WIND
ADVISORIES OR WARNINGS.

LAKE SHORE FLOODING CONTINUES TO BE AN ISSUE...ESPECIALLY IN
CHICAGO...WHERE WAVES HAVE BEEN GETTING WATER ONTO LAKE SHORE DRIVE.
WE CONSIDERED TO UPGRADE TO A LAKE SHORE FLOOD WARNING...BUT DECIDED
TO JUST BEEF UP THE WORDING IN THE CURRENT ADVISORY AS A WARNING
WOULD NOT DUE MUCH GOOD AT THIS STAGE OF THE GAME.

KJB

&&

.LONG TERM...
307 PM CDT

TOMORROW THROUGH THURSDAY...

SATURDAY AND SUNDAY...
THE UPPER LEVEL TROUGH PUSHES EAST ALLOWING A LARGE UPPER LEVEL
RIDGE TO MOVE OVERHEAD THROUGH THE WEEKEND. THE CORRESPONDING
SURFACE HIGH MOVES OVER THE REGION TOMORROW EVENING.

GUIDANCE CONTINUES TO FEATURE A NARROW CONVERGENCE BAND ALONG THE
SOUTHWEST END OF LAKE MICHIGAN EARLY SATURDAY MORNING.  KEPT A
SLIGHT CHANCE OF PRECIP IN FOR FAR NORTHEAST IL WITH THE BAND
DISSIPATING BY LATE MORNING/EARLY AFTERNOON AS FORCING AND MOISTURE
WEAKEN. NOT EXPECTING ANY ADDITIONAL SIGNIFICANT ACCUMULATION AND
THE PRECIP TYPE WILL BE A SNOW/RAIN MIX AS TEMPERATURES WILL BE
ABOVE FREEZING OVER THE LAKE.  HAVE MEDIUM CONFIDENCE IN THE BAND
PERSISTING UNTIL MORNING...MEDIUM HIGH CONFIDENCE IN THE BAND MAINLY
IMPACTING THE IL SIDE OF THE LAKE...AND HIGH CONFIDENCE IN LITTLE TO
NO ADDITIONAL ACCUMULATION.

WINDS DECREASE SATURDAY AS THE HIGH MOVES OVERHEAD.  WARMER AIR
BEGINS TO MOVE IN AS WELL WITH HIGHS IN THE LOW 40S TOMORROW. WINDS
TURN SOUTH BEHIND THE HIGH SUNDAY AND USHER IN EVEN WARMER AIR WITH
HIGHS IN THE UPPER 40S TO AROUND 50. SATURDAY AFTERNOON THROUGH
SUNDAY NIGHT WILL BE DRY.

MONDAY THROUGH THURSDAY...
THE RIDGE AXIS MOVES OVERHEAD MONDAY AS THE SURFACE LOW SLIDES OVER
THE SE U.S. THE WARM-UP CONTINUES WITH HIGHS IN THE UPPER 50S TO
AROUND 60 MONDAY...AND MID 50S EXPECTED THROUGH MID WEEK. OVERNIGHT
LOWS VARY FROM THE MID 40S MONDAY NIGHT TO THE MID TO LOWER 30S
THURSDAY NIGHT.

A SURFACE LOW MOVES INTO ONTARIO TUESDAY...AND IT DRAGS A COLD FRONT
ACROSS THE REGION TUESDAY. EXPECTING WIDESPREAD SHOWERS TUESDAY
MORNING WITH RAIN ENDING FROM WEST TO EAST AS THE FRONT SLIDES EAST
TUESDAY EVENING/NIGHT.  GUIDANCE DIFFERS ON HOW MUCH PRECIP WILL
FALL...BUT ITS LOOKING LIKE A GOOD WETTING RAIN IS EXPECTED.

A WEAKER LOW PASSES JUST TO OUR NORTH MID WEEK AND HAVE MEDIUM-LOW
CONFIDENCE IN PRECIP MAKING IT INTO NORTHERN IL WEDNESDAY. THINKING
PRECIP WILL REMAIN CLOSELY TIED TO THE LOW WHICH RIGHT NOW WILL BE
OVER SOUTHERN WI. IF THE LOW/S TRACK WERE TO DIP A BIT MORE
SOUTH...THERE WOULD BE A BETTER CHANCE FOR PRECIP ACROSS FAR
NORTHERN IL.

WINDS TURN NORTHWEST BEHIND THE LOW AND ANOTHER LAKE EFFECT PRECIP
SITUATION IS POSSIBLE FOR NW INDIANA WEDNESDAY NIGHT. ONLY HAVE RAIN
FOR NOW AS TEMPS WILL BE ABOVE FREEZING.  WINDS REMAIN OFF OF THE
LAKE THROUGH THURSDAY NIGHT AS ANOTHER HIGH PRESSURE SYSTEM
APPROACHES FROM THE WEST.

JEE

&&

.AVIATION...

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

* NORTH WINDS GUSTING AROUND 30 KT AT 00Z...SLOWLY DIMINISHING
  THIS EVENING.

* LAKE EFFECT SNOW SHOWERS AFFECTING MDW...AND EXPECTED TO DRIFT
  WEST ACROSS ORD LATER THIS EVENING. MVFR CIGS/BRIEF IFR VIS IN
  -SHSN ESPECIALLY AT MDW. SNOW SHOWERS CONTINUE OVERNIGHT BUT
  WEAKEN AFTER MIDNIGHT.

* MVFR CIGS LINGER SATURDAY...THOUGH RISE WITH TIME AND SCATTER
  LATE.

RATZER

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

VERY GUSTY NORTH WINDS CONTINUE TO SLOWLY DIMINISH EARLY THIS
EVENING AS REGION OF TIGHT SURFACE PRESSURE GRADIENT AND STRONG
PRESSURE RISES AHEAD OF HIGH PRESSURE MOVE SOUTHEAST OF THE
TERMINALS. GUST SHOULD DECREASE BELOW 30 KT 00-02Z FOR CHICAGO
TERMINALS WITH THE EXCEPTION OF GYY...WHERE WIND RIGHT OFF LAKE
MICHIGAN WILL PRODUCE SLOWLY DIMINISHING GUSTS OF 40+ KTS. WINDS
CONTINUE TO SHIFT SLOWLY TO THE NORTH-NORTHEAST SATURDAY MORNING
WITH SPEEDS AND GUSTS CONTINUING TO STEADILY DIMINISH DURING THE
DAY.

LAKE EFFECT RAIN/SNOW SHOWERS OCCURRING IN MULTI-CELLULAR NORTH-
SOUTH BAND ACROSS THE LAKE WERE AFFECTING GYY AND MDW AT TAF
ISSUANCE...THOUGH WITH GRADUAL NORTH-NORTHEASTWARD SHIFT OF
BOUNDARY LAYER FLOW SNOW SHOWERS WILL LIKELY SPREAD WEST INTO ORD
BY MID EVENING. WITHIN AREA OF SNOW SHOWERS...MVFR CIGS AND
OCCASIONAL IFR VISIBILITIES CAN BE EXPECTED...WITH A GRADUAL
DECREASE IN INTENSITY AFTER MIDNIGHT AS HIGH PRESSURE BUILDS
TOWARD THE REGION AND INVERSION LEVELS LOWER. NORTH-NORTHEAST
WINDS WILL LIKELY MAINTAIN MID-HIGH RANGE MVFR CIGS INTO
SATURDAY...THOUGH WITH RISING BASES AND EVENTUAL SCATTERING LATER
IN THE DAY.

RATZER

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

* HIGH CONFIDENCE IN WIND TRENDS.

* MEDIUM CONFIDENCE IN -SHSN TRENDS...AND CIG/VIS IMPACTS.

* MEDIUM CONFIDENCE IN MVFR CIG DURATION SATURDAY.

RATZER

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

SUNDAY...DRY/VFR. SOUTH WINDS 10-15 KT.

MONDAY...DRY/VFR DURING THE DAY. SHRA LIKELY MONDAY NIGHT. GUSTY
SOUTHWEST WINDS 15-20 KT.

TUESDAY...SHRA/MVFR LIKELY. SOUTHWEST WINDS.

WEDNESDAY...DRY/VFR. SOUTHWEST WINDS.

THURSDAY...DRY/VFR. WEST-NORTHWEST WINDS.

RATZER

&&

.MARINE...
212 PM CDT

STORM FORCE WINDS WILL SLOWLY EASE TO GALES TONIGHT. NO CHANGES
PLANNED TO CURRENT HEADLINES.

FOR THE NEARSHORE ZONES...WILL NEED A PROLONGED SMALL CRAFT ADVISORY
THROUGH AT LEAST SATURDAY AS VERY LARGE WAVES SUBSIDE.  MAY FLIRT
WITH SMALL CRAFT ADVISORY CRITERIA WINDS AND WAVES SUNDAY AND
MONDAY. HAVE MEDIUM CONFIDENCE AS CONDITIONS MAY BE MARGINAL.

NORTH TO NORTHEAST WINDS TO 30 KT SLOWLY DIMINISH SATURDAY AND WINDS
TURN SOUTHWEST BEHIND A HIGH PRESSURE SYSTEM SUNDAY MORNING.  SOUTH
TO SOUTHWEST WINDS INCREASE TO 30 KT SUNDAY AFTERNOON AS THE
GRADIENT TIGHTENS BETWEEN THE DEPARTING HIGH AND AN APPROACHING
LOW.  SOUTH TO SOUTHWEST WINDS FINALLY DIMINISH TO UNDER 30 KT
MONDAY NIGHT...AND THEN WINDS TURN WEST 10-20 KT BEHIND THE LOWS
COLD FRONT TUESDAY. WEST WINDS INCREASE TO 20-25 KT AND BECOME
NORTHWEST WEDNESDAY NIGHT...AND MAY SEE 30 KT WINDS OVER THE
NORTHERN HALF OF THE LAKE THURSDAY.  WINDS DIMINISH THURSDAY NIGHT
AS HIGH PRESSURE MOVES OVER THE AREA.

KJB/JEE

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...LAKESHORE FLOOD ADVISORY...ILZ014 UNTIL 4 AM SATURDAY.

IN...LAKE EFFECT SNOW ADVISORY...INZ001-INZ002-INZ010-INZ011 UNTIL 10
     PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...INZ001-INZ002 UNTIL 4 AM SATURDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-
     LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 4 AM
     SATURDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563 UNTIL 10 PM FRIDAY.

&&

$$

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

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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000
FXUS63 KILX 010131
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
831 PM CDT Fri Oct 31 2014

.UPDATE...
ISSUED AT 825 PM CDT FRI OCT 31 2014

Lake moisuture continues to stream south-southwest into our area
this evening affecting areas mainly along and east of the I-55
corridor. Broad cyclonic flow forecast to continue thru the
early morning hours with the past several runs of the HRRR
indicating the band of moisture will be shrinking and affecting
areas of east central thru southeast Illinois overnight. Still
could see some scattered flurries over extreme eastern IL thru
midnight before the better setup for flurries shifts into west
central Indiana. Forecast has these trends well in hand this
evening so other than some minor adjustments to the sky cover
for this evening, no other changes were made to the grids. No
evening ZFP update will be needed.

Will freshen up the wording in our NPW product and have that out
by 845 pm.

&&

.SHORT TERM...(Tonight)
ISSUED AT 304 PM CDT FRI OCT 31 2014

Increased pressure gradient behind the cold front has created a
blustery day across Central Illinois.  In combination with colder
air moving into the region, wind chills are dropping in the 30s.
Although the winds are expected to slowly decrease after sunset...it
will be very slow and accompanied by dropping temperatures as well.
As a result, going into Halloween night, trick or treaters will
encounter temperatures in the upper 30s and lower 40s...with winds
still in the 20 to 25 mph range and occasionally very gusty early.
Wind chills at or below freezing for the few hours around sunset.
Temperatures tonight will drop mainly into the 20s and provide a
significant hard freeze for the end of October.  Though there is
some spread in the MOS for this event, vast majority keep the 20s in
place.  Some remaining lake effect snow/rain will dwindle into the
overnight hours, mainly impacting the extreme eastern IL/IN border
with flurries and light rain.  Accumulations are not expected.

&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 304 PM CDT FRI OCT 31 2014

Cold high pressure will settle over Illinois during the day Saturday
bringing much lighter winds, continuing through Saturday night. The
light winds and dry air mass will allow for another night of sub
freezing temperatures due to good radiational cooling. Temperatures
will moderate somewhat Sunday, but still remain much below average
with highs mainly in the upper 40s.

More unsettled weather is on track Monday to Wednesday as moist
southwesterly flow develops ahead of a strong upper level trough
digging into the southern Rockies. A frontal boundary will set up
from the southern Plains NE into the Ohio river valley Monday night
through Wed to bring chances for showers, especially Monday night
and Tuesday. Milder temperatures can be expected in this time
period, with highs in the upper 50s and lows mainly in the 40s.
Model data indicates weak instability with this system, meaning
thunderstorms are unlikely. Drier weather is expected Wed night thru
Friday as dry west northwesterly flow trails the system. Expect
seasonable highs generally in the mid to upper 50s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 600 PM CDT FRI OCT 31 2014

Most areas should see VFR conditions this period. The only
exception will be KBMI and KCMI where some clouds moving
south-southwest off of Lake Michigan may affect those two
sites for most of this evening, and possibly during the
early morning hours. Broad north to northeast flow off the
warm waters of Lake Michigan will continue to stream clouds
into parts of east central Illinois into Saturday morning
before the flow shifts the bulk of the clouds east of our
area. Surface winds will gradually diminish overnight,
especially the gusts from the north and northwest. By
morning, areas along and east of I55 will see northerly
winds at 10 to 15 kts, and further west, winds should be
northerly at around 10 kts most of the day.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING from Midnight tonight to 9 AM CDT Saturday FOR
ILZ027>031-036>038-040>057-061>063-066>068-071>073.

&&

$$

UPDATE...Smith
SHORT TERM...HJS
LONG TERM...Onton
AVIATION...Smith







000
FXUS63 KLOT 312342
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
642 PM CDT FRI OCT 31 2014

.UPDATE...
556 PM CDT

MINOR UPDATE TO NEAR TERM GRIDS IN PARTICULAR INCREASING POPS
OVER NORTHEAST ILLINOIS AND HEIGHTENING FROZEN PRECIP TYPE...AS
WELL AS EXTENDING THE HIGH WIND WARNING THROUGH THIS EVENING.

LATEST RADAR IMAGERY SHOWING UNORGANIZED BANDS OF LAKE EFFECT
PRECIP CONTINUING TO SPILL INTO PORTIONS OF NORTHEAST ILLINOIS AND
NORTHWEST INDIANA AT THIS HOUR. CURRENT OBSERVATIONAL DATA AS WELL
AS MANY SPOTTER/PUBLIC/SOCIAL MEDIA REPORTS DEPICTING A VARIETY OF
PRECIP TYPES CURRENTLY ONGOING RANGING FROM SNOW...SLEET...AND
RAIN. WHILE OVERALL COLUMN IS SUFFICIENTLY COLD ENOUGH FOR FROZEN
PRECIP...LATEST AMDAR AND SHORT TERM FORECAST SOUNDINGS STILL
SHOWING A HIGHLY VARIABLE THERMAL PROFILE WITHIN THE BOUNDARY
LAYER. WARMER LAKE AIR SPILLING INTO AREAS IMMEDIATELY NEAR THE
LAKE STILL HELPING FOR A RAIN SNOW MIX...WHILE AREAS INLAND
OBSERVING MORE OF A SNOW AND SLEET MIX. THESE VARYING PRECIP TYPES
ACROSS THOSE LOCATIONS WILL LIKELY CONTINUE OVER THE NEXT SEVERAL
HOURS...BEFORE BOUNDARY LAYER SUFFICIENTLY COOLS FOR ALL SNOW OVER
ALL LOCATIONS. THIS WILL OCCUR WHILE LOW LEVEL FLOW AND STRONGEST
OBSERVED CONVERGENCE OVER NORTHWEST INDIANA VEERS...WITH THE FOCUS
THEN SHIFTING MORE INTO ILLINOIS. ALTHOUGH DURING THIS
TIME...BETTER SYNOPTIC SUPPORT WILL EXIT...INVERSIONS WILL
LOWER...SATURATION FOR SNOW GROWTH DIMINISHES...AND CONVERGENCE
ALSO WEAKENS.

WINDS STILL RATHER STRONG AT THIS HOUR AND ALTHOUGH THEY WILL
DIMINISH IN THE NEAR TERM...STRONGEST WINDS SHOULD STILL REMAIN
NEAR HIGH WIND WARNING CRITERIA...ESPECIALLY FOR AREAS NEAR THE
LAKE. DID EXTEND THE CURRENT HIGH WIND WARNING TO 10 PM...BUT WILL
POSSIBLY OBSERVE A FURTHER DIMINISHING TREND PRIOR TO THIS HOUR.

RODRIGUEZ

&&

.SHORT TERM...
307 PM CDT

THROUGH TONIGHT...

NO CHANGES PLANNED WITH HEADLINES.

SEVERAL BANDS OF LAKE EFFECT SNOW HAVE DEVELOPED ACROSS SOUTHERN
LAKE MICHIGAN EARLY THIS AFTERNOON...WITH SOME OF THESE SNOW SHOWERS
IMPACTING PORTIONS OF THE NORTHEASTERN ILLINOIS SHORES.
HOWEVER...THE MOST SUBSTANTIAL AREA OF LAKE EFFECT RAIN AND SNOW HAS
BEEN OCCURRING ALONG THE SOUTHERN TIP OF LAKE MICHIGAN AND ACROSS THE
ADVISORY AREA OF NORTHWESTERN INDIANA. BASED ON NUMEROUS PHONE
CALLS ACROSS THIS AREA IT APPEARS AREAS NEAR THE LAKE ARE SLIGHTLY
WARMER...RESULTING IN A RAIN SNOW MIX. HOWEVER...AREAS ROUGHLY 20 TO
30 MILES INLAND (BASICALLY ALONG AND SOUTH OF A CROWN POINT TO
VALPARAISO INDIANA LINE) THE PRECIPITATION IS MAINLY IN THE FORM OF
SNOW. SEVERAL REPORTS OF ACCUMULATING SNOW HAVE BEEN RECEIVED SOUTH
OF THIS LINE...WITH LOW VISIBILITIES UNDER A MILE.

BASED ON CURRENT RADAR TRENDS AND SHORT RANGE HIRES GUIDANCE...IT
APPEARS THIS ACTIVITY WILL CONTINUE TO BE FOCUSED MAINLY ACROSS
NORTHWESTERN INDIANA FOR THE NEXT FEW HOURS...THROUGH LATE
AFTERNOON/EARLY THIS EVENING. HOWEVER...SOME OF THE LESS ORGANIZED LAKE
EFFECT SNOW SHOWERS WILL LIKELY IMPACT PORTIONS OF COOK AND LAKE
COUNTIES IN ILLINOIS AS WELL DURING THIS TIME. FINALLY...AS THE
SURFACE LOW SHIFTS SOUTHEAST OVER THE OHIO VALLEY INTO THIS EVENING
THE BOUNDARY LAYER FLOW WILL VEER AND WEAKEN A BIT. THIS SHOULD
ALLOW THE BETTER FOCUS FOR LAKE EFFECT SHOWERS TO SHIFT FARTHER WEST
ACROSS PORTIONS OF EASTERN ILLINOIS...INCLUDING THE CHICAGO METRO
AREA NEAR THE LAKE. WHILE THERE COULD BE A SHORT PERIOD OF SOME
MODERATE...OR EVEN BRIEFLY HEAVY SNOW SHOWERS INTO NORTHEASTERN
ILLINOIS INTO THIS EVENING...I HAVE CHOSEN NOT TO EXTEND THE WINTER
ADVISORIES FARTHER WEST INTO ILLINOIS. THIS IS MAINLY DUE TO THE
FACT THAT IT APPEARS THE THREAT FOR BETTER MORE ORGANIZED LAKE
EFFECT SNOW WILL BE OF SHORT DURATION...LIMITING OVERALL
ACCUMULATIONS. HEIGHT RISES AND WARMING TEMPERATURES IN THE MID
LEVELS SHOULD ALLOW INVERSION HEIGHTS TO DROP BELOW THE DENDRITIC
GROWTH ZONE BY LATER THIS EVENING/OVERNIGHT. THE MODELS HAVE BEEN
INSISTENT ON THIS FOR THE PAST FEW DAYS AND SEE NO REASON WHY THIS
WOULD NOT OCCUR AS THE UPPER RIDGE TO OUR WEST BEGINS TO BUILD
EASTWARD. THEREFORE...ANY LEFT OVER LAKE EFFECT SNOW SHOWERS WILL
LIKELY NOT BE EFFICIENT SNOWFALL PRODUCERS AND LIKELY BE LOOSELY
ORGANIZED...AND HENCE THE THREAT FOR ACCUMULATING SNOWFALL SHOULD
COME TO AN END BY LATER THIS EVENING.

THE WINDS WITH THIS SYSTEM HAVE BEEN IMPRESSIVE. KGYY HAS BEEN
EXPERIENCING GUSTS TO 58 KT FOR SEVERAL HOURS...WITH SIMILAR
MAGNITUDES NOTED ALONG THE LAKE SHORE. IT APPEARS THESE STRONG WINDS
WILL SLOWLY EASE TONIGHT AS THE SURFACE HIGH OVERSPREADS THE AREA ON
SATURDAY. THEREFORE...NO CHANGES ARE PLANNED WITH THE CURRENT WIND
ADVISORIES OR WARNINGS.

LAKE SHORE FLOODING CONTINUES TO BE AN ISSUE...ESPECIALLY IN
CHICAGO...WHERE WAVES HAVE BEEN GETTING WATER ONTO LAKE SHORE DRIVE.
WE CONSIDERED TO UPGRADE TO A LAKE SHORE FLOOD WARNING...BUT DECIDED
TO JUST BEEF UP THE WORDING IN THE CURRENT ADVISORY AS A WARNING
WOULD NOT DUE MUCH GOOD AT THIS STAGE OF THE GAME.

KJB

&&

.LONG TERM...
307 PM CDT

TOMORROW THROUGH THURSDAY...

SATURDAY AND SUNDAY...
THE UPPER LEVEL TROUGH PUSHES EAST ALLOWING A LARGE UPPER LEVEL
RIDGE TO MOVE OVERHEAD THROUGH THE WEEKEND. THE CORRESPONDING
SURFACE HIGH MOVES OVER THE REGION TOMORROW EVENING.

GUIDANCE CONTINUES TO FEATURE A NARROW CONVERGENCE BAND ALONG THE
SOUTHWEST END OF LAKE MICHIGAN EARLY SATURDAY MORNING.  KEPT A
SLIGHT CHANCE OF PRECIP IN FOR FAR NORTHEAST IL WITH THE BAND
DISSIPATING BY LATE MORNING/EARLY AFTERNOON AS FORCING AND MOISTURE
WEAKEN. NOT EXPECTING ANY ADDITIONAL SIGNIFICANT ACCUMULATION AND
THE PRECIP TYPE WILL BE A SNOW/RAIN MIX AS TEMPERATURES WILL BE
ABOVE FREEZING OVER THE LAKE.  HAVE MEDIUM CONFIDENCE IN THE BAND
PERSISTING UNTIL MORNING...MEDIUM HIGH CONFIDENCE IN THE BAND MAINLY
IMPACTING THE IL SIDE OF THE LAKE...AND HIGH CONFIDENCE IN LITTLE TO
NO ADDITIONAL ACCUMULATION.

WINDS DECREASE SATURDAY AS THE HIGH MOVES OVERHEAD.  WARMER AIR
BEGINS TO MOVE IN AS WELL WITH HIGHS IN THE LOW 40S TOMORROW. WINDS
TURN SOUTH BEHIND THE HIGH SUNDAY AND USHER IN EVEN WARMER AIR WITH
HIGHS IN THE UPPER 40S TO AROUND 50. SATURDAY AFTERNOON THROUGH
SUNDAY NIGHT WILL BE DRY.

MONDAY THROUGH THURSDAY...
THE RIDGE AXIS MOVES OVERHEAD MONDAY AS THE SURFACE LOW SLIDES OVER
THE SE U.S. THE WARM-UP CONTINUES WITH HIGHS IN THE UPPER 50S TO
AROUND 60 MONDAY...AND MID 50S EXPECTED THROUGH MID WEEK. OVERNIGHT
LOWS VARY FROM THE MID 40S MONDAY NIGHT TO THE MID TO LOWER 30S
THURSDAY NIGHT.

A SURFACE LOW MOVES INTO ONTARIO TUESDAY...AND IT DRAGS A COLD FRONT
ACROSS THE REGION TUESDAY. EXPECTING WIDESPREAD SHOWERS TUESDAY
MORNING WITH RAIN ENDING FROM WEST TO EAST AS THE FRONT SLIDES EAST
TUESDAY EVENING/NIGHT.  GUIDANCE DIFFERS ON HOW MUCH PRECIP WILL
FALL...BUT ITS LOOKING LIKE A GOOD WETTING RAIN IS EXPECTED.

A WEAKER LOW PASSES JUST TO OUR NORTH MID WEEK AND HAVE MEDIUM-LOW
CONFIDENCE IN PRECIP MAKING IT INTO NORTHERN IL WEDNESDAY. THINKING
PRECIP WILL REMAIN CLOSELY TIED TO THE LOW WHICH RIGHT NOW WILL BE
OVER SOUTHERN WI. IF THE LOW/S TRACK WERE TO DIP A BIT MORE
SOUTH...THERE WOULD BE A BETTER CHANCE FOR PRECIP ACROSS FAR
NORTHERN IL.

WINDS TURN NORTHWEST BEHIND THE LOW AND ANOTHER LAKE EFFECT PRECIP
SITUATION IS POSSIBLE FOR NW INDIANA WEDNESDAY NIGHT. ONLY HAVE RAIN
FOR NOW AS TEMPS WILL BE ABOVE FREEZING.  WINDS REMAIN OFF OF THE
LAKE THROUGH THURSDAY NIGHT AS ANOTHER HIGH PRESSURE SYSTEM
APPROACHES FROM THE WEST.

JEE

&&

.AVIATION...

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

* NORTH WINDS GUSTING AROUND 30 KT AT 00Z...SLOWLY DIMINISHING
  THIS EVENING.

* LAKE EFFECT SNOW SHOWERS AFFECTING MDW...AND EXPECTED TO DRIFT
  WEST ACROSS ORD LATER THIS EVENING. MVFR CIGS/BRIEF IFR VIS IN
  -SHSN ESPECIALLY AT MDW. SNOW SHOWERS CONTINUE OVERNIGHT BUT
  WEAKEN AFTER MIDNIGHT.

* MVFR CIGS LINGER SATURDAY...THOUGH RISE WITH TIME AND SCATTER
  LATE.

RATZER

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

VERY GUSTY NORTH WINDS CONTINUE TO SLOWLY DIMINISH EARLY THIS
EVENING AS REGION OF TIGHT SURFACE PRESSURE GRADIENT AND STRONG
PRESSURE RISES AHEAD OF HIGH PRESSURE MOVE SOUTHEAST OF THE
TERMINALS. GUST SHOULD DECREASE BELOW 30 KT 00-02Z FOR CHICAGO
TERMINALS WITH THE EXCEPTION OF GYY...WHERE WIND RIGHT OFF LAKE
MICHIGAN WILL PRODUCE SLOWLY DIMINISHING GUSTS OF 40+ KTS. WINDS
CONTINUE TO SHIFT SLOWLY TO THE NORTH-NORTHEAST SATURDAY MORNING
WITH SPEEDS AND GUSTS CONTINUING TO STEADILY DIMINISH DURING THE
DAY.

LAKE EFFECT RAIN/SNOW SHOWERS OCCURRING IN MULTI-CELLULAR NORTH-
SOUTH BAND ACROSS THE LAKE WERE AFFECTING GYY AND MDW AT TAF
ISSUANCE...THOUGH WITH GRADUAL NORTH-NORTHEASTWARD SHIFT OF
BOUNDARY LAYER FLOW SNOW SHOWERS WILL LIKELY SPREAD WEST INTO ORD
BY MID EVENING. WITHIN AREA OF SNOW SHOWERS...MVFR CIGS AND
OCCASIONAL IFR VISIBILITIES CAN BE EXPECTED...WITH A GRADUAL
DECREASE IN INTENSITY AFTER MIDNIGHT AS HIGH PRESSURE BUILDS
TOWARD THE REGION AND INVERSION LEVELS LOWER. NORTH-NORTHEAST
WINDS WILL LIKELY MAINTAIN MID-HIGH RANGE MVFR CIGS INTO
SATURDAY...THOUGH WITH RISING BASES AND EVENTUAL SCATTERING LATER
IN THE DAY.

RATZER


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

* HIGH CONFIDENCE IN WIND TRENDS.

* MEDIUM CONFIDENCE IN -SHSN TRENDS...AND CIG/VIS IMPACTS.

* MEDIUM CONFIDENCE IN MVFR CIG DURATION SATURDAY.

RATZER

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

SUNDAY...DRY/VFR. SOUTH WINDS 10-15 KT.

MONDAY...DRY/VFR DURING THE DAY. SHRA LIKELY MONDAY NIGHT. GUSTY
SOUTHWEST WINDS 15-20 KT.

TUESDAY...SHRA/MVFR LIKELY. SOUTHWEST WINDS.

WEDNESDAY...DRY/VFR. SOUTHWEST WINDS.

THURSDAY...DRY/VFR. WEST-NORTHWEST WINDS.

RATZER

&&

.MARINE...
212 PM CDT

STORM FORCE WINDS WILL SLOWLY EASE TO GALES TONIGHT. NO CHANGES
PLANNED TO CURRENT HEADLINES.

FOR THE NEARSHORE ZONES...WILL NEED A PROLONGED SMALL CRAFT ADVISORY
THROUGH AT LEAST SATURDAY AS VERY LARGE WAVES SUBSIDE.  MAY FLIRT
WITH SMALL CRAFT ADVISORY CRITERIA WINDS AND WAVES SUNDAY AND
MONDAY. HAVE MEDIUM CONFIDENCE AS CONDITIONS MAY BE MARGINAL.

NORTH TO NORTHEAST WINDS TO 30 KT SLOWLY DIMINISH SATURDAY AND WINDS
TURN SOUTHWEST BEHIND A HIGH PRESSURE SYSTEM SUNDAY MORNING.  SOUTH
TO SOUTHWEST WINDS INCREASE TO 30 KT SUNDAY AFTERNOON AS THE
GRADIENT TIGHTENS BETWEEN THE DEPARTING HIGH AND AN APPROACHING
LOW.  SOUTH TO SOUTHWEST WINDS FINALLY DIMINISH TO UNDER 30 KT
MONDAY NIGHT...AND THEN WINDS TURN WEST 10-20 KT BEHIND THE LOWS
COLD FRONT TUESDAY. WEST WINDS INCREASE TO 20-25 KT AND BECOME
NORTHWEST WEDNESDAY NIGHT...AND MAY SEE 30 KT WINDS OVER THE
NORTHERN HALF OF THE LAKE THURSDAY.  WINDS DIMINISH THURSDAY NIGHT
AS HIGH PRESSURE MOVES OVER THE AREA.

KJB/JEE

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HIGH WIND WARNING...ILZ014 UNTIL 10 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014 UNTIL 4 AM SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022-ILZ023-
     ILZ033 UNTIL 7 PM FRIDAY.

IN...HIGH WIND WARNING...INZ001-INZ002 UNTIL 10 PM FRIDAY.

     LAKE EFFECT SNOW ADVISORY...INZ001-INZ002-INZ010-INZ011 UNTIL 10
     PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...INZ001-INZ002 UNTIL 4 AM SATURDAY.

     WIND ADVISORY...INZ010-INZ011-INZ019 UNTIL 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 4 AM
     SATURDAY.

     STORM WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563 UNTIL 10 PM FRIDAY.

     GALE WARNING...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 4 AM SATURDAY.

&&

$$

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

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







000
FXUS63 KILX 312305
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
605 PM CDT Fri Oct 31 2014

.SHORT TERM...(Tonight)
ISSUED AT 304 PM CDT FRI OCT 31 2014

Increased pressure gradient behind the cold front has created a
blustery day across Central Illinois.  In combination with colder
air moving into the region, wind chills are dropping in the 30s.
Although the winds are expected to slowly decrease after sunset...it
will be very slow and accompanied by dropping temperatures as well.
As a result, going into Halloween night, trick or treaters will
encounter temperatures in the upper 30s and lower 40s...with winds
still in the 20 to 25 mph range and occasionally very gusty early.
Wind chills at or below freezing for the few hours around sunset.
Temperatures tonight will drop mainly into the 20s and provide a
significant hard freeze for the end of October.  Though there is
some spread in the MOS for this event, vast majority keep the 20s in
place.  Some remaining lake effect snow/rain will dwindle into the
overnight hours, mainly impacting the extreme eastern IL/IN border
with flurries and light rain.  Accumulations are not expected.

&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 304 PM CDT FRI OCT 31 2014

Cold high pressure will settle over Illinois during the day Saturday
bringing much lighter winds, continuing through Saturday night. The
light winds and dry air mass will allow for another night of sub
freezing temperatures due to good radiational cooling. Temperatures
will moderate somewhat Sunday, but still remain much below average
with highs mainly in the upper 40s.

More unsettled weather is on track Monday to Wednesday as moist
southwesterly flow develops ahead of a strong upper level trough
digging into the southern Rockies. A frontal boundary will set up
from the southern Plains NE into the Ohio river valley Monday night
through Wed to bring chances for showers, especially Monday night
and Tuesday. Milder temperatures can be expected in this time
period, with highs in the upper 50s and lows mainly in the 40s.
Model data indicates weak instability with this system, meaning
thunderstorms are unlikely. Drier weather is expected Wed night thru
Friday as dry west northwesterly flow trails the system. Expect
seasonable highs generally in the mid to upper 50s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 600 PM CDT FRI OCT 31 2014

Most areas should see VFR conditions this period. The only
exception will be KBMI and KCMI where some clouds moving
south-southwest off of Lake Michigan may affect those two
sites for most of this evening, and possibly during the
early morning hours. Broad north to northeast flow off the
warm waters of Lake Michigan will continue to stream clouds
into parts of east central Illinois into Saturday morning
before the flow shifts the bulk of the clouds east of our
area. Surface winds will gradually diminish overnight,
especially the gusts from the north and northwest. By
morning, areas along and east of I55 will see northerly
winds at 10 to 15 kts, and further west, winds should be
northerly at around 10 kts most of the day.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING from Midnight tonight to 9 AM CDT Saturday FOR
ILZ027>031-036>038-040>057-061>063-066>068-071>073.

&&

$$

SHORT TERM...HJS
LONG TERM...Onton
AVIATION...Smith





000
FXUS63 KILX 312305
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
605 PM CDT Fri Oct 31 2014

.SHORT TERM...(Tonight)
ISSUED AT 304 PM CDT FRI OCT 31 2014

Increased pressure gradient behind the cold front has created a
blustery day across Central Illinois.  In combination with colder
air moving into the region, wind chills are dropping in the 30s.
Although the winds are expected to slowly decrease after sunset...it
will be very slow and accompanied by dropping temperatures as well.
As a result, going into Halloween night, trick or treaters will
encounter temperatures in the upper 30s and lower 40s...with winds
still in the 20 to 25 mph range and occasionally very gusty early.
Wind chills at or below freezing for the few hours around sunset.
Temperatures tonight will drop mainly into the 20s and provide a
significant hard freeze for the end of October.  Though there is
some spread in the MOS for this event, vast majority keep the 20s in
place.  Some remaining lake effect snow/rain will dwindle into the
overnight hours, mainly impacting the extreme eastern IL/IN border
with flurries and light rain.  Accumulations are not expected.

&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 304 PM CDT FRI OCT 31 2014

Cold high pressure will settle over Illinois during the day Saturday
bringing much lighter winds, continuing through Saturday night. The
light winds and dry air mass will allow for another night of sub
freezing temperatures due to good radiational cooling. Temperatures
will moderate somewhat Sunday, but still remain much below average
with highs mainly in the upper 40s.

More unsettled weather is on track Monday to Wednesday as moist
southwesterly flow develops ahead of a strong upper level trough
digging into the southern Rockies. A frontal boundary will set up
from the southern Plains NE into the Ohio river valley Monday night
through Wed to bring chances for showers, especially Monday night
and Tuesday. Milder temperatures can be expected in this time
period, with highs in the upper 50s and lows mainly in the 40s.
Model data indicates weak instability with this system, meaning
thunderstorms are unlikely. Drier weather is expected Wed night thru
Friday as dry west northwesterly flow trails the system. Expect
seasonable highs generally in the mid to upper 50s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 600 PM CDT FRI OCT 31 2014

Most areas should see VFR conditions this period. The only
exception will be KBMI and KCMI where some clouds moving
south-southwest off of Lake Michigan may affect those two
sites for most of this evening, and possibly during the
early morning hours. Broad north to northeast flow off the
warm waters of Lake Michigan will continue to stream clouds
into parts of east central Illinois into Saturday morning
before the flow shifts the bulk of the clouds east of our
area. Surface winds will gradually diminish overnight,
especially the gusts from the north and northwest. By
morning, areas along and east of I55 will see northerly
winds at 10 to 15 kts, and further west, winds should be
northerly at around 10 kts most of the day.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING from Midnight tonight to 9 AM CDT Saturday FOR
ILZ027>031-036>038-040>057-061>063-066>068-071>073.

&&

$$

SHORT TERM...HJS
LONG TERM...Onton
AVIATION...Smith





000
FXUS63 KLOT 312302 AAA
AFDLOT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
602 PM CDT FRI OCT 31 2014

.UPDATE...
556 PM CDT

MINOR UPDATE TO NEAR TERM GRIDS IN PARTICULAR INCREASING POPS
OVER NORTHEAST ILLINOIS AND HEIGHTENING FROZEN PRECIP TYPE...AS
WELL AS EXTENDING THE HIGH WIND WARNING THROUGH THIS EVENING.

LATEST RADAR IMAGERY SHOWING UNORGANIZED BANDS OF LAKE EFFECT
PRECIP CONTINUING TO SPILL INTO PORTIONS OF NORTHEAST ILLINOIS AND
NORTHWEST INDIANA AT THIS HOUR. CURRENT OBSERVATIONAL DATA AS WELL
AS MANY SPOTTER/PUBLIC/SOCIAL MEDIA REPORTS DEPICTING A VARIETY OF
PRECIP TYPES CURRENTLY ONGOING RANGING FROM SNOW...SLEET...AND
RAIN. WHILE OVERALL COLUMN IS SUFFICIENTLY COLD ENOUGH FOR FROZEN
PRECIP...LATEST AMDAR AND SHORT TERM FORECAST SOUNDINGS STILL
SHOWING A HIGHLY VARIABLE THERMAL PROFILE WITHIN THE BOUNDARY
LAYER. WARMER LAKE AIR SPILLING INTO AREAS IMMEDIATELY NEAR THE
LAKE STILL HELPING FOR A RAIN SNOW MIX...WHILE AREAS INLAND
OBSERVING MORE OF A SNOW AND SLEET MIX. THESE VARYING PRECIP TYPES
ACROSS THOSE LOCATIONS WILL LIKELY CONTINUE OVER THE NEXT SEVERAL
HOURS...BEFORE BOUNDARY LAYER SUFFICIENTLY COOLS FOR ALL SNOW OVER
ALL LOCATIONS. THIS WILL OCCUR WHILE LOW LEVEL FLOW AND STRONGEST
OBSERVED CONVERGENCE OVER NORTHWEST INDIANA VEERS...WITH THE FOCUS
THEN SHIFTING MORE INTO ILLINOIS. ALTHOUGH DURING THIS
TIME...BETTER SYNOPTIC SUPPORT WILL EXIT...INVERSIONS WILL
LOWER...SATURATION FOR SNOW GROWTH DIMINISHES...AND CONVERGENCE
ALSO WEAKENS.

WINDS STILL RATHER STRONG AT THIS HOUR AND ALTHOUGH THEY WILL
DIMINISH IN THE NEAR TERM...STRONGEST WINDS SHOULD STILL REMAIN
NEAR HIGH WIND WARNING CRITERIA...ESPECIALLY FOR AREAS NEAR THE
LAKE. DID EXTEND THE CURRENT HIGH WIND WARNING TO 10 PM...BUT WILL
POSSIBLY OBSERVE A FURTHER DIMINISHING TREND PRIOR TO THIS HOUR.

RODRIGUEZ

&&

.SHORT TERM...
307 PM CDT

THROUGH TONIGHT...

NO CHANGES PLANNED WITH HEADLINES.

SEVERAL BANDS OF LAKE EFFECT SNOW HAVE DEVELOPED ACROSS SOUTHERN
LAKE MICHIGAN EARLY THIS AFTERNOON...WITH SOME OF THESE SNOW SHOWERS
IMPACTING PORTIONS OF THE NORTHEASTERN ILLINOIS SHORES.
HOWEVER...THE MOST SUBSTANTIAL AREA OF LAKE EFFECT RAIN AND SNOW HAS
BEEN OCCURRING ALONG THE SOUTHERN TIP OF LAKE MICHIGAN AND ACROSS THE
ADVISORY AREA OF NORTHWESTERN INDIANA. BASED ON NUMEROUS PHONE
CALLS ACROSS THIS AREA IT APPEARS AREAS NEAR THE LAKE ARE SLIGHTLY
WARMER...RESULTING IN A RAIN SNOW MIX. HOWEVER...AREAS ROUGHLY 20 TO
30 MILES INLAND (BASICALLY ALONG AND SOUTH OF A CROWN POINT TO
VALPARAISO INDIANA LINE) THE PRECIPITATION IS MAINLY IN THE FORM OF
SNOW. SEVERAL REPORTS OF ACCUMULATING SNOW HAVE BEEN RECEIVED SOUTH
OF THIS LINE...WITH LOW VISIBILITIES UNDER A MILE.

BASED ON CURRENT RADAR TRENDS AND SHORT RANGE HIRES GUIDANCE...IT
APPEARS THIS ACTIVITY WILL CONTINUE TO BE FOCUSED MAINLY ACROSS
NORTHWESTERN INDIANA FOR THE NEXT FEW HOURS...THROUGH LATE
AFTERNOON/EARLY THIS EVENING. HOWEVER...SOME OF THE LESS ORGANIZED LAKE
EFFECT SNOW SHOWERS WILL LIKELY IMPACT PORTIONS OF COOK AND LAKE
COUNTIES IN ILLINOIS AS WELL DURING THIS TIME. FINALLY...AS THE
SURFACE LOW SHIFTS SOUTHEAST OVER THE OHIO VALLEY INTO THIS EVENING
THE BOUNDARY LAYER FLOW WILL VEER AND WEAKEN A BIT. THIS SHOULD
ALLOW THE BETTER FOCUS FOR LAKE EFFECT SHOWERS TO SHIFT FARTHER WEST
ACROSS PORTIONS OF EASTERN ILLINOIS...INCLUDING THE CHICAGO METRO
AREA NEAR THE LAKE. WHILE THERE COULD BE A SHORT PERIOD OF SOME
MODERATE...OR EVEN BRIEFLY HEAVY SNOW SHOWERS INTO NORTHEASTERN
ILLINOIS INTO THIS EVENING...I HAVE CHOSEN NOT TO EXTEND THE WINTER
ADVISORIES FARTHER WEST INTO ILLINOIS. THIS IS MAINLY DUE TO THE
FACT THAT IT APPEARS THE THREAT FOR BETTER MORE ORGANIZED LAKE
EFFECT SNOW WILL BE OF SHORT DURATION...LIMITING OVERALL
ACCUMULATIONS. HEIGHT RISES AND WARMING TEMPERATURES IN THE MID
LEVELS SHOULD ALLOW INVERSION HEIGHTS TO DROP BELOW THE DENDRITIC
GROWTH ZONE BY LATER THIS EVENING/OVERNIGHT. THE MODELS HAVE BEEN
INSISTENT ON THIS FOR THE PAST FEW DAYS AND SEE NO REASON WHY THIS
WOULD NOT OCCUR AS THE UPPER RIDGE TO OUR WEST BEGINS TO BUILD
EASTWARD. THEREFORE...ANY LEFT OVER LAKE EFFECT SNOW SHOWERS WILL
LIKELY NOT BE EFFICIENT SNOWFALL PRODUCERS AND LIKELY BE LOOSELY
ORGANIZED...AND HENCE THE THREAT FOR ACCUMULATING SNOWFALL SHOULD
COME TO AN END BY LATER THIS EVENING.

THE WINDS WITH THIS SYSTEM HAVE BEEN IMPRESSIVE. KGYY HAS BEEN
EXPERIENCING GUSTS TO 58 KT FOR SEVERAL HOURS...WITH SIMILAR
MAGNITUDES NOTED ALONG THE LAKE SHORE. IT APPEARS THESE STRONG WINDS
WILL SLOWLY EASE TONIGHT AS THE SURFACE HIGH OVERSPREADS THE AREA ON
SATURDAY. THEREFORE...NO CHANGES ARE PLANNED WITH THE CURRENT WIND
ADVISORIES OR WARNINGS.

LAKE SHORE FLOODING CONTINUES TO BE AN ISSUE...ESPECIALLY IN
CHICAGO...WHERE WAVES HAVE BEEN GETTING WATER ONTO LAKE SHORE DRIVE.
WE CONSIDERED TO UPGRADE TO A LAKE SHORE FLOOD WARNING...BUT DECIDED
TO JUST BEEF UP THE WORDING IN THE CURRENT ADVISORY AS A WARNING
WOULD NOT DUE MUCH GOOD AT THIS STAGE OF THE GAME.

KJB

&&

.LONG TERM...
307 PM CDT

TOMORROW THROUGH THURSDAY...

SATURDAY AND SUNDAY...
THE UPPER LEVEL TROUGH PUSHES EAST ALLOWING A LARGE UPPER LEVEL
RIDGE TO MOVE OVERHEAD THROUGH THE WEEKEND. THE CORRESPONDING
SURFACE HIGH MOVES OVER THE REGION TOMORROW EVENING.

GUIDANCE CONTINUES TO FEATURE A NARROW CONVERGENCE BAND ALONG THE
SOUTHWEST END OF LAKE MICHIGAN EARLY SATURDAY MORNING.  KEPT A
SLIGHT CHANCE OF PRECIP IN FOR FAR NORTHEAST IL WITH THE BAND
DISSIPATING BY LATE MORNING/EARLY AFTERNOON AS FORCING AND MOISTURE
WEAKEN. NOT EXPECTING ANY ADDITIONAL SIGNIFICANT ACCUMULATION AND
THE PRECIP TYPE WILL BE A SNOW/RAIN MIX AS TEMPERATURES WILL BE
ABOVE FREEZING OVER THE LAKE.  HAVE MEDIUM CONFIDENCE IN THE BAND
PERSISTING UNTIL MORNING...MEDIUM HIGH CONFIDENCE IN THE BAND MAINLY
IMPACTING THE IL SIDE OF THE LAKE...AND HIGH CONFIDENCE IN LITTLE TO
NO ADDITIONAL ACCUMULATION.

WINDS DECREASE SATURDAY AS THE HIGH MOVES OVERHEAD.  WARMER AIR
BEGINS TO MOVE IN AS WELL WITH HIGHS IN THE LOW 40S TOMORROW. WINDS
TURN SOUTH BEHIND THE HIGH SUNDAY AND USHER IN EVEN WARMER AIR WITH
HIGHS IN THE UPPER 40S TO AROUND 50. SATURDAY AFTERNOON THROUGH
SUNDAY NIGHT WILL BE DRY.

MONDAY THROUGH THURSDAY...
THE RIDGE AXIS MOVES OVERHEAD MONDAY AS THE SURFACE LOW SLIDES OVER
THE SE U.S. THE WARM-UP CONTINUES WITH HIGHS IN THE UPPER 50S TO
AROUND 60 MONDAY...AND MID 50S EXPECTED THROUGH MID WEEK. OVERNIGHT
LOWS VARY FROM THE MID 40S MONDAY NIGHT TO THE MID TO LOWER 30S
THURSDAY NIGHT.

A SURFACE LOW MOVES INTO ONTARIO TUESDAY...AND IT DRAGS A COLD FRONT
ACROSS THE REGION TUESDAY. EXPECTING WIDESPREAD SHOWERS TUESDAY
MORNING WITH RAIN ENDING FROM WEST TO EAST AS THE FRONT SLIDES EAST
TUESDAY EVENING/NIGHT.  GUIDANCE DIFFERS ON HOW MUCH PRECIP WILL
FALL...BUT ITS LOOKING LIKE A GOOD WETTING RAIN IS EXPECTED.

A WEAKER LOW PASSES JUST TO OUR NORTH MID WEEK AND HAVE MEDIUM-LOW
CONFIDENCE IN PRECIP MAKING IT INTO NORTHERN IL WEDNESDAY. THINKING
PRECIP WILL REMAIN CLOSELY TIED TO THE LOW WHICH RIGHT NOW WILL BE
OVER SOUTHERN WI. IF THE LOW/S TRACK WERE TO DIP A BIT MORE
SOUTH...THERE WOULD BE A BETTER CHANCE FOR PRECIP ACROSS FAR
NORTHERN IL.

WINDS TURN NORTHWEST BEHIND THE LOW AND ANOTHER LAKE EFFECT PRECIP
SITUATION IS POSSIBLE FOR NW INDIANA WEDNESDAY NIGHT. ONLY HAVE RAIN
FOR NOW AS TEMPS WILL BE ABOVE FREEZING.  WINDS REMAIN OFF OF THE
LAKE THROUGH THURSDAY NIGHT AS ANOTHER HIGH PRESSURE SYSTEM
APPROACHES FROM THE WEST.

JEE

&&

.AVIATION...

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

* VERY GUSTY NORTH WINDS WITH GUSTS IN EXCESS OF 30 KT INTO EARLY
  EVENING...01-02Z.

* LAKE EFFECT RAIN/SNOW SHOWERS AT MDW WITH OCCASIONAL IFR VIS AT
  MDW THIS AFTERNOON...DRIFTING WEST INTO ORD THIS EVENING.

* INTENSIFYING LAKE EFFECT SNOW SHOWERS PROBABLE OVER MDW LATER
  THIS EVE. SNOW SHOWERS PERSISTING POSSIBLY AS LONG AS EARLY
  SATURDAY MORNING. SNOW SHOWERS POSSIBLE AT ORD.

* CIGS TEMPORARY TO 1500-3000 FT AT MDW LATE THIS AFTERNOON. CIGS
  GRADUALLY LOWERING TO 1500-2500 FT AT BOTH AIRPORTS LATER
  TONIGHT.

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

VERY GUSTY NORTH-NORTHWEST WINDS WILL CONTINUE THROUGH THIS
AFTERNOON AS COLD AIR CONTINUES TO REPLENISH ITSELF. GUSTS OF 33
TO 40 KT...WITH EVEN SPORADICALLY HIGHER ARE HIGHLY LIKELY TO BE
COMMON THROUGH THE AFTERNOON. DURING THE AFTERNOON...DUE TO THE
ORIENTATION OF THE PRESSURE GRADIENT...THE WIND DIRECTION IS
EXPECTED TO SHIFT TO 360 DEGREES AT CHICAGOLAND TAF SITES. LAKE
EFFECT SNOW...MAYBE AT TIMES RAIN...WILL CONTINUE TO IMPACT GARY
THROUGHOUT THIS AFTERNOON AND TONIGHT. WITH SOME BANDING
POTENTIAL THIS EVE VISIBILITY COULD DROP QUITE LOW DURING THAT
PERIOD. THE SNOW BAND...OR AREA OF SHOWERS...WILL BEGIN TO INCH
BACK WESTWARD THIS EVE INTO OVERNIGHT. THE INTENSITY OF SNOW COULD
STILL BE FAIRLY IMPRESSIVE AT MDW LATER THIS EVE...ALTHOUGH A
DECENT AMOUNT OF UNCERTAINTY EXISTS THERE. AT LEAST LAKE-INDUCED
CLOUDS ARE LIKELY OVER NORTHEAST ILLINOIS SATURDAY MORNING
ALTHOUGH THERE COULD CONTINUE SOME SNOW SHOWERS TOO. AT THE SAME
TIME WINDS ARE FAVORED TO BE BETWEEN 360-020 DEGREES...SO IMPACTS
TO ORD OPERATIONS COULD CONTINUE THROUGH SATURDAY MORNING.

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

* HIGH IN WIND SPEEDS AND DIRECTION THROUGH 00Z. MEDIUM THEREAFTER.

* MEDIUM IN HOW FAR VISIBILITY WILL DROP IN SNOW SHOWERS LATE THIS
  AFTERNOON AND EARLY THIS EVE.

* MEDIUM IN SNOW SHOWERS IMPACTING MDW LATER TONIGHT AND LOW FOR
  ORD. LOW IN HOW FAR VISIBILITY WILL DROP AT EITHER AIRPORT.

* MEDIUM IN CIGS THROUGH TAF.

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

* SATURDAY NIGHT...DRY VFR. LIGHT/VARIABLE WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS 10-15 KT.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.
* TUESDAY...SHRA/MVFR LIKELY. SOUTHWEST WINDS.
* WEDNESDAY...DRY/VFR. SOUTHWEST WINDS.
* THURSDAY...DRY/VFR. WEST WINDS.

MTF

&&

.MARINE...
212 PM CDT

STORM FORCE WINDS WILL SLOWLY EASE TO GALES TONIGHT. NO CHANGES
PLANNED TO CURRENT HEADLINES.

FOR THE NEARSHORE ZONES...WILL NEED A PROLONGED SMALL CRAFT ADVISORY
THROUGH AT LEAST SATURDAY AS VERY LARGE WAVES SUBSIDE.  MAY FLIRT
WITH SMALL CRAFT ADVISORY CRITERIA WINDS AND WAVES SUNDAY AND
MONDAY. HAVE MEDIUM CONFIDENCE AS CONDITIONS MAY BE MARGINAL.

NORTH TO NORTHEAST WINDS TO 30 KT SLOWLY DIMINISH SATURDAY AND WINDS
TURN SOUTHWEST BEHIND A HIGH PRESSURE SYSTEM SUNDAY MORNING.  SOUTH
TO SOUTHWEST WINDS INCREASE TO 30 KT SUNDAY AFTERNOON AS THE
GRADIENT TIGHTENS BETWEEN THE DEPARTING HIGH AND AN APPROACHING
LOW.  SOUTH TO SOUTHWEST WINDS FINALLY DIMINISH TO UNDER 30 KT
MONDAY NIGHT...AND THEN WINDS TURN WEST 10-20 KT BEHIND THE LOWS
COLD FRONT TUESDAY. WEST WINDS INCREASE TO 20-25 KT AND BECOME
NORTHWEST WEDNESDAY NIGHT...AND MAY SEE 30 KT WINDS OVER THE
NORTHERN HALF OF THE LAKE THURSDAY.  WINDS DIMINISH THURSDAY NIGHT
AS HIGH PRESSURE MOVES OVER THE AREA.

KJB/JEE

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HIGH WIND WARNING...ILZ014 UNTIL 10 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014 UNTIL 4 AM SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022-ILZ023-
     ILZ033 UNTIL 7 PM FRIDAY.

IN...HIGH WIND WARNING...INZ001-INZ002 UNTIL 10 PM FRIDAY.

     LAKE EFFECT SNOW ADVISORY...INZ001-INZ002-INZ010-INZ011 UNTIL 10
     PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...INZ001-INZ002 UNTIL 4 AM SATURDAY.

     WIND ADVISORY...INZ010-INZ011-INZ019 UNTIL 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 4 AM
     SATURDAY.

     STORM WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563 UNTIL 10 PM FRIDAY.

     GALE WARNING...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 4 AM SATURDAY.

&&

$$

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

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








000
FXUS63 KLOT 312302 AAA
AFDLOT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
602 PM CDT FRI OCT 31 2014

.UPDATE...
556 PM CDT

MINOR UPDATE TO NEAR TERM GRIDS IN PARTICULAR INCREASING POPS
OVER NORTHEAST ILLINOIS AND HEIGHTENING FROZEN PRECIP TYPE...AS
WELL AS EXTENDING THE HIGH WIND WARNING THROUGH THIS EVENING.

LATEST RADAR IMAGERY SHOWING UNORGANIZED BANDS OF LAKE EFFECT
PRECIP CONTINUING TO SPILL INTO PORTIONS OF NORTHEAST ILLINOIS AND
NORTHWEST INDIANA AT THIS HOUR. CURRENT OBSERVATIONAL DATA AS WELL
AS MANY SPOTTER/PUBLIC/SOCIAL MEDIA REPORTS DEPICTING A VARIETY OF
PRECIP TYPES CURRENTLY ONGOING RANGING FROM SNOW...SLEET...AND
RAIN. WHILE OVERALL COLUMN IS SUFFICIENTLY COLD ENOUGH FOR FROZEN
PRECIP...LATEST AMDAR AND SHORT TERM FORECAST SOUNDINGS STILL
SHOWING A HIGHLY VARIABLE THERMAL PROFILE WITHIN THE BOUNDARY
LAYER. WARMER LAKE AIR SPILLING INTO AREAS IMMEDIATELY NEAR THE
LAKE STILL HELPING FOR A RAIN SNOW MIX...WHILE AREAS INLAND
OBSERVING MORE OF A SNOW AND SLEET MIX. THESE VARYING PRECIP TYPES
ACROSS THOSE LOCATIONS WILL LIKELY CONTINUE OVER THE NEXT SEVERAL
HOURS...BEFORE BOUNDARY LAYER SUFFICIENTLY COOLS FOR ALL SNOW OVER
ALL LOCATIONS. THIS WILL OCCUR WHILE LOW LEVEL FLOW AND STRONGEST
OBSERVED CONVERGENCE OVER NORTHWEST INDIANA VEERS...WITH THE FOCUS
THEN SHIFTING MORE INTO ILLINOIS. ALTHOUGH DURING THIS
TIME...BETTER SYNOPTIC SUPPORT WILL EXIT...INVERSIONS WILL
LOWER...SATURATION FOR SNOW GROWTH DIMINISHES...AND CONVERGENCE
ALSO WEAKENS.

WINDS STILL RATHER STRONG AT THIS HOUR AND ALTHOUGH THEY WILL
DIMINISH IN THE NEAR TERM...STRONGEST WINDS SHOULD STILL REMAIN
NEAR HIGH WIND WARNING CRITERIA...ESPECIALLY FOR AREAS NEAR THE
LAKE. DID EXTEND THE CURRENT HIGH WIND WARNING TO 10 PM...BUT WILL
POSSIBLY OBSERVE A FURTHER DIMINISHING TREND PRIOR TO THIS HOUR.

RODRIGUEZ

&&

.SHORT TERM...
307 PM CDT

THROUGH TONIGHT...

NO CHANGES PLANNED WITH HEADLINES.

SEVERAL BANDS OF LAKE EFFECT SNOW HAVE DEVELOPED ACROSS SOUTHERN
LAKE MICHIGAN EARLY THIS AFTERNOON...WITH SOME OF THESE SNOW SHOWERS
IMPACTING PORTIONS OF THE NORTHEASTERN ILLINOIS SHORES.
HOWEVER...THE MOST SUBSTANTIAL AREA OF LAKE EFFECT RAIN AND SNOW HAS
BEEN OCCURRING ALONG THE SOUTHERN TIP OF LAKE MICHIGAN AND ACROSS THE
ADVISORY AREA OF NORTHWESTERN INDIANA. BASED ON NUMEROUS PHONE
CALLS ACROSS THIS AREA IT APPEARS AREAS NEAR THE LAKE ARE SLIGHTLY
WARMER...RESULTING IN A RAIN SNOW MIX. HOWEVER...AREAS ROUGHLY 20 TO
30 MILES INLAND (BASICALLY ALONG AND SOUTH OF A CROWN POINT TO
VALPARAISO INDIANA LINE) THE PRECIPITATION IS MAINLY IN THE FORM OF
SNOW. SEVERAL REPORTS OF ACCUMULATING SNOW HAVE BEEN RECEIVED SOUTH
OF THIS LINE...WITH LOW VISIBILITIES UNDER A MILE.

BASED ON CURRENT RADAR TRENDS AND SHORT RANGE HIRES GUIDANCE...IT
APPEARS THIS ACTIVITY WILL CONTINUE TO BE FOCUSED MAINLY ACROSS
NORTHWESTERN INDIANA FOR THE NEXT FEW HOURS...THROUGH LATE
AFTERNOON/EARLY THIS EVENING. HOWEVER...SOME OF THE LESS ORGANIZED LAKE
EFFECT SNOW SHOWERS WILL LIKELY IMPACT PORTIONS OF COOK AND LAKE
COUNTIES IN ILLINOIS AS WELL DURING THIS TIME. FINALLY...AS THE
SURFACE LOW SHIFTS SOUTHEAST OVER THE OHIO VALLEY INTO THIS EVENING
THE BOUNDARY LAYER FLOW WILL VEER AND WEAKEN A BIT. THIS SHOULD
ALLOW THE BETTER FOCUS FOR LAKE EFFECT SHOWERS TO SHIFT FARTHER WEST
ACROSS PORTIONS OF EASTERN ILLINOIS...INCLUDING THE CHICAGO METRO
AREA NEAR THE LAKE. WHILE THERE COULD BE A SHORT PERIOD OF SOME
MODERATE...OR EVEN BRIEFLY HEAVY SNOW SHOWERS INTO NORTHEASTERN
ILLINOIS INTO THIS EVENING...I HAVE CHOSEN NOT TO EXTEND THE WINTER
ADVISORIES FARTHER WEST INTO ILLINOIS. THIS IS MAINLY DUE TO THE
FACT THAT IT APPEARS THE THREAT FOR BETTER MORE ORGANIZED LAKE
EFFECT SNOW WILL BE OF SHORT DURATION...LIMITING OVERALL
ACCUMULATIONS. HEIGHT RISES AND WARMING TEMPERATURES IN THE MID
LEVELS SHOULD ALLOW INVERSION HEIGHTS TO DROP BELOW THE DENDRITIC
GROWTH ZONE BY LATER THIS EVENING/OVERNIGHT. THE MODELS HAVE BEEN
INSISTENT ON THIS FOR THE PAST FEW DAYS AND SEE NO REASON WHY THIS
WOULD NOT OCCUR AS THE UPPER RIDGE TO OUR WEST BEGINS TO BUILD
EASTWARD. THEREFORE...ANY LEFT OVER LAKE EFFECT SNOW SHOWERS WILL
LIKELY NOT BE EFFICIENT SNOWFALL PRODUCERS AND LIKELY BE LOOSELY
ORGANIZED...AND HENCE THE THREAT FOR ACCUMULATING SNOWFALL SHOULD
COME TO AN END BY LATER THIS EVENING.

THE WINDS WITH THIS SYSTEM HAVE BEEN IMPRESSIVE. KGYY HAS BEEN
EXPERIENCING GUSTS TO 58 KT FOR SEVERAL HOURS...WITH SIMILAR
MAGNITUDES NOTED ALONG THE LAKE SHORE. IT APPEARS THESE STRONG WINDS
WILL SLOWLY EASE TONIGHT AS THE SURFACE HIGH OVERSPREADS THE AREA ON
SATURDAY. THEREFORE...NO CHANGES ARE PLANNED WITH THE CURRENT WIND
ADVISORIES OR WARNINGS.

LAKE SHORE FLOODING CONTINUES TO BE AN ISSUE...ESPECIALLY IN
CHICAGO...WHERE WAVES HAVE BEEN GETTING WATER ONTO LAKE SHORE DRIVE.
WE CONSIDERED TO UPGRADE TO A LAKE SHORE FLOOD WARNING...BUT DECIDED
TO JUST BEEF UP THE WORDING IN THE CURRENT ADVISORY AS A WARNING
WOULD NOT DUE MUCH GOOD AT THIS STAGE OF THE GAME.

KJB

&&

.LONG TERM...
307 PM CDT

TOMORROW THROUGH THURSDAY...

SATURDAY AND SUNDAY...
THE UPPER LEVEL TROUGH PUSHES EAST ALLOWING A LARGE UPPER LEVEL
RIDGE TO MOVE OVERHEAD THROUGH THE WEEKEND. THE CORRESPONDING
SURFACE HIGH MOVES OVER THE REGION TOMORROW EVENING.

GUIDANCE CONTINUES TO FEATURE A NARROW CONVERGENCE BAND ALONG THE
SOUTHWEST END OF LAKE MICHIGAN EARLY SATURDAY MORNING.  KEPT A
SLIGHT CHANCE OF PRECIP IN FOR FAR NORTHEAST IL WITH THE BAND
DISSIPATING BY LATE MORNING/EARLY AFTERNOON AS FORCING AND MOISTURE
WEAKEN. NOT EXPECTING ANY ADDITIONAL SIGNIFICANT ACCUMULATION AND
THE PRECIP TYPE WILL BE A SNOW/RAIN MIX AS TEMPERATURES WILL BE
ABOVE FREEZING OVER THE LAKE.  HAVE MEDIUM CONFIDENCE IN THE BAND
PERSISTING UNTIL MORNING...MEDIUM HIGH CONFIDENCE IN THE BAND MAINLY
IMPACTING THE IL SIDE OF THE LAKE...AND HIGH CONFIDENCE IN LITTLE TO
NO ADDITIONAL ACCUMULATION.

WINDS DECREASE SATURDAY AS THE HIGH MOVES OVERHEAD.  WARMER AIR
BEGINS TO MOVE IN AS WELL WITH HIGHS IN THE LOW 40S TOMORROW. WINDS
TURN SOUTH BEHIND THE HIGH SUNDAY AND USHER IN EVEN WARMER AIR WITH
HIGHS IN THE UPPER 40S TO AROUND 50. SATURDAY AFTERNOON THROUGH
SUNDAY NIGHT WILL BE DRY.

MONDAY THROUGH THURSDAY...
THE RIDGE AXIS MOVES OVERHEAD MONDAY AS THE SURFACE LOW SLIDES OVER
THE SE U.S. THE WARM-UP CONTINUES WITH HIGHS IN THE UPPER 50S TO
AROUND 60 MONDAY...AND MID 50S EXPECTED THROUGH MID WEEK. OVERNIGHT
LOWS VARY FROM THE MID 40S MONDAY NIGHT TO THE MID TO LOWER 30S
THURSDAY NIGHT.

A SURFACE LOW MOVES INTO ONTARIO TUESDAY...AND IT DRAGS A COLD FRONT
ACROSS THE REGION TUESDAY. EXPECTING WIDESPREAD SHOWERS TUESDAY
MORNING WITH RAIN ENDING FROM WEST TO EAST AS THE FRONT SLIDES EAST
TUESDAY EVENING/NIGHT.  GUIDANCE DIFFERS ON HOW MUCH PRECIP WILL
FALL...BUT ITS LOOKING LIKE A GOOD WETTING RAIN IS EXPECTED.

A WEAKER LOW PASSES JUST TO OUR NORTH MID WEEK AND HAVE MEDIUM-LOW
CONFIDENCE IN PRECIP MAKING IT INTO NORTHERN IL WEDNESDAY. THINKING
PRECIP WILL REMAIN CLOSELY TIED TO THE LOW WHICH RIGHT NOW WILL BE
OVER SOUTHERN WI. IF THE LOW/S TRACK WERE TO DIP A BIT MORE
SOUTH...THERE WOULD BE A BETTER CHANCE FOR PRECIP ACROSS FAR
NORTHERN IL.

WINDS TURN NORTHWEST BEHIND THE LOW AND ANOTHER LAKE EFFECT PRECIP
SITUATION IS POSSIBLE FOR NW INDIANA WEDNESDAY NIGHT. ONLY HAVE RAIN
FOR NOW AS TEMPS WILL BE ABOVE FREEZING.  WINDS REMAIN OFF OF THE
LAKE THROUGH THURSDAY NIGHT AS ANOTHER HIGH PRESSURE SYSTEM
APPROACHES FROM THE WEST.

JEE

&&

.AVIATION...

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

* VERY GUSTY NORTH WINDS WITH GUSTS IN EXCESS OF 30 KT INTO EARLY
  EVENING...01-02Z.

* LAKE EFFECT RAIN/SNOW SHOWERS AT MDW WITH OCCASIONAL IFR VIS AT
  MDW THIS AFTERNOON...DRIFTING WEST INTO ORD THIS EVENING.

* INTENSIFYING LAKE EFFECT SNOW SHOWERS PROBABLE OVER MDW LATER
  THIS EVE. SNOW SHOWERS PERSISTING POSSIBLY AS LONG AS EARLY
  SATURDAY MORNING. SNOW SHOWERS POSSIBLE AT ORD.

* CIGS TEMPORARY TO 1500-3000 FT AT MDW LATE THIS AFTERNOON. CIGS
  GRADUALLY LOWERING TO 1500-2500 FT AT BOTH AIRPORTS LATER
  TONIGHT.

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

VERY GUSTY NORTH-NORTHWEST WINDS WILL CONTINUE THROUGH THIS
AFTERNOON AS COLD AIR CONTINUES TO REPLENISH ITSELF. GUSTS OF 33
TO 40 KT...WITH EVEN SPORADICALLY HIGHER ARE HIGHLY LIKELY TO BE
COMMON THROUGH THE AFTERNOON. DURING THE AFTERNOON...DUE TO THE
ORIENTATION OF THE PRESSURE GRADIENT...THE WIND DIRECTION IS
EXPECTED TO SHIFT TO 360 DEGREES AT CHICAGOLAND TAF SITES. LAKE
EFFECT SNOW...MAYBE AT TIMES RAIN...WILL CONTINUE TO IMPACT GARY
THROUGHOUT THIS AFTERNOON AND TONIGHT. WITH SOME BANDING
POTENTIAL THIS EVE VISIBILITY COULD DROP QUITE LOW DURING THAT
PERIOD. THE SNOW BAND...OR AREA OF SHOWERS...WILL BEGIN TO INCH
BACK WESTWARD THIS EVE INTO OVERNIGHT. THE INTENSITY OF SNOW COULD
STILL BE FAIRLY IMPRESSIVE AT MDW LATER THIS EVE...ALTHOUGH A
DECENT AMOUNT OF UNCERTAINTY EXISTS THERE. AT LEAST LAKE-INDUCED
CLOUDS ARE LIKELY OVER NORTHEAST ILLINOIS SATURDAY MORNING
ALTHOUGH THERE COULD CONTINUE SOME SNOW SHOWERS TOO. AT THE SAME
TIME WINDS ARE FAVORED TO BE BETWEEN 360-020 DEGREES...SO IMPACTS
TO ORD OPERATIONS COULD CONTINUE THROUGH SATURDAY MORNING.

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

* HIGH IN WIND SPEEDS AND DIRECTION THROUGH 00Z. MEDIUM THEREAFTER.

* MEDIUM IN HOW FAR VISIBILITY WILL DROP IN SNOW SHOWERS LATE THIS
  AFTERNOON AND EARLY THIS EVE.

* MEDIUM IN SNOW SHOWERS IMPACTING MDW LATER TONIGHT AND LOW FOR
  ORD. LOW IN HOW FAR VISIBILITY WILL DROP AT EITHER AIRPORT.

* MEDIUM IN CIGS THROUGH TAF.

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

* SATURDAY NIGHT...DRY VFR. LIGHT/VARIABLE WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS 10-15 KT.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.
* TUESDAY...SHRA/MVFR LIKELY. SOUTHWEST WINDS.
* WEDNESDAY...DRY/VFR. SOUTHWEST WINDS.
* THURSDAY...DRY/VFR. WEST WINDS.

MTF

&&

.MARINE...
212 PM CDT

STORM FORCE WINDS WILL SLOWLY EASE TO GALES TONIGHT. NO CHANGES
PLANNED TO CURRENT HEADLINES.

FOR THE NEARSHORE ZONES...WILL NEED A PROLONGED SMALL CRAFT ADVISORY
THROUGH AT LEAST SATURDAY AS VERY LARGE WAVES SUBSIDE.  MAY FLIRT
WITH SMALL CRAFT ADVISORY CRITERIA WINDS AND WAVES SUNDAY AND
MONDAY. HAVE MEDIUM CONFIDENCE AS CONDITIONS MAY BE MARGINAL.

NORTH TO NORTHEAST WINDS TO 30 KT SLOWLY DIMINISH SATURDAY AND WINDS
TURN SOUTHWEST BEHIND A HIGH PRESSURE SYSTEM SUNDAY MORNING.  SOUTH
TO SOUTHWEST WINDS INCREASE TO 30 KT SUNDAY AFTERNOON AS THE
GRADIENT TIGHTENS BETWEEN THE DEPARTING HIGH AND AN APPROACHING
LOW.  SOUTH TO SOUTHWEST WINDS FINALLY DIMINISH TO UNDER 30 KT
MONDAY NIGHT...AND THEN WINDS TURN WEST 10-20 KT BEHIND THE LOWS
COLD FRONT TUESDAY. WEST WINDS INCREASE TO 20-25 KT AND BECOME
NORTHWEST WEDNESDAY NIGHT...AND MAY SEE 30 KT WINDS OVER THE
NORTHERN HALF OF THE LAKE THURSDAY.  WINDS DIMINISH THURSDAY NIGHT
AS HIGH PRESSURE MOVES OVER THE AREA.

KJB/JEE

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HIGH WIND WARNING...ILZ014 UNTIL 10 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014 UNTIL 4 AM SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022-ILZ023-
     ILZ033 UNTIL 7 PM FRIDAY.

IN...HIGH WIND WARNING...INZ001-INZ002 UNTIL 10 PM FRIDAY.

     LAKE EFFECT SNOW ADVISORY...INZ001-INZ002-INZ010-INZ011 UNTIL 10
     PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...INZ001-INZ002 UNTIL 4 AM SATURDAY.

     WIND ADVISORY...INZ010-INZ011-INZ019 UNTIL 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 4 AM
     SATURDAY.

     STORM WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563 UNTIL 10 PM FRIDAY.

     GALE WARNING...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 4 AM SATURDAY.

&&

$$

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

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








000
FXUS63 KLOT 312207
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
507 PM CDT FRI OCT 31 2014

.SHORT TERM...
307 PM CDT

THROUGH TONIGHT...

NO CHANGES PLANNED WITH HEADLINES.

SEVERAL BANDS OF LAKE EFFECT SNOW HAVE DEVELOPED ACROSS SOUTHERN
LAKE MICHIGAN EARLY THIS AFTERNOON...WITH SOME OF THESE SNOW SHOWERS
IMPACTING PORTIONS OF THE NORTHEASTERN ILLINOIS SHORES.
HOWEVER...THE MOST SUBSTANTIAL AREA OF LAKE EFFECT RAIN AND SNOW HAS
BEEN OCCURRING ALONG THE SOUTHERN TIP OF LAKE MICHIGAN AND ACROSS THE
ADVISORY AREA OF NORTHWESTERN INDIANA. BASED ON NUMEROUS PHONE
CALLS ACROSS THIS AREA IT APPEARS AREAS NEAR THE LAKE ARE SLIGHTLY
WARMER...RESULTING IN A RAIN SNOW MIX. HOWEVER...AREAS ROUGHLY 20 TO
30 MILES INLAND (BASICALLY ALONG AND SOUTH OF A CROWN POINT TO
VALPARAISO INDIANA LINE) THE PRECIPITATION IS MAINLY IN THE FORM OF
SNOW. SEVERAL REPORTS OF ACCUMULATING SNOW HAVE BEEN RECEIVED SOUTH
OF THIS LINE...WITH LOW VISIBILITIES UNDER A MILE.

BASED ON CURRENT RADAR TRENDS AND SHORT RANGE HIRES GUIDANCE...IT
APPEARS THIS ACTIVITY WILL CONTINUE TO BE FOCUSED MAINLY ACROSS
NORTHWESTERN INDIANA FOR THE NEXT FEW HOURS...THROUGH LATE
AFTERNOON/EARLY THIS EVENING. HOWEVER...SOME OF THE LESS ORGANIZED LAKE
EFFECT SNOW SHOWERS WILL LIKELY IMPACT PORTIONS OF COOK AND LAKE
COUNTIES IN ILLINOIS AS WELL DURING THIS TIME. FINALLY...AS THE
SURFACE LOW SHIFTS SOUTHEAST OVER THE OHIO VALLEY INTO THIS EVENING
THE BOUNDARY LAYER FLOW WILL VEER AND WEAKEN A BIT. THIS SHOULD
ALLOW THE BETTER FOCUS FOR LAKE EFFECT SHOWERS TO SHIFT FARTHER WEST
ACROSS PORTIONS OF EASTERN ILLINOIS...INCLUDING THE CHICAGO METRO
AREA NEAR THE LAKE. WHILE THERE COULD BE A SHORT PERIOD OF SOME
MODERATE...OR EVEN BRIEFLY HEAVY SNOW SHOWERS INTO NORTHEASTERN
ILLINOIS INTO THIS EVENING...I HAVE CHOSEN NOT TO EXTEND THE WINTER
ADVISORIES FARTHER WEST INTO ILLINOIS. THIS IS MAINLY DUE TO THE
FACT THAT IT APPEARS THE THREAT FOR BETTER MORE ORGANIZED LAKE
EFFECT SNOW WILL BE OF SHORT DURATION...LIMITING OVERALL
ACCUMULATIONS. HEIGHT RISES AND WARMING TEMPERATURES IN THE MID
LEVELS SHOULD ALLOW INVERSION HEIGHTS TO DROP BELOW THE DENDRITIC
GROWTH ZONE BY LATER THIS EVENING/OVERNIGHT. THE MODELS HAVE BEEN
INSISTENT ON THIS FOR THE PAST FEW DAYS AND SEE NO REASON WHY THIS
WOULD NOT OCCUR AS THE UPPER RIDGE TO OUR WEST BEGINS TO BUILD
EASTWARD. THEREFORE...ANY LEFT OVER LAKE EFFECT SNOW SHOWERS WILL
LIKELY NOT BE EFFICIENT SNOWFALL PRODUCERS AND LIKELY BE LOOSELY
ORGANIZED...AND HENCE THE THREAT FOR ACCUMULATING SNOWFALL SHOULD
COME TO AN END BY LATER THIS EVENING.

THE WINDS WITH THIS SYSTEM HAVE BEEN IMPRESSIVE. KGYY HAS BEEN
EXPERIENCING GUSTS TO 58 KT FOR SEVERAL HOURS...WITH SIMILAR
MAGNITUDES NOTED ALONG THE LAKE SHORE. IT APPEARS THESE STRONG WINDS
WILL SLOWLY EASE TONIGHT AS THE SURFACE HIGH OVERSPREADS THE AREA ON
SATURDAY. THEREFORE...NO CHANGES ARE PLANNED WITH THE CURRENT WIND
ADVISORIES OR WARNINGS.

LAKE SHORE FLOODING CONTINUES TO BE AN ISSUE...ESPECIALLY IN
CHICAGO...WHERE WAVES HAVE BEEN GETTING WATER ONTO LAKE SHORE DRIVE.
WE CONSIDERED TO UPGRADE TO A LAKE SHORE FLOOD WARNING...BUT DECIDED
TO JUST BEEF UP THE WORDING IN THE CURRENT ADVISORY AS A WARNING
WOULD NOT DUE MUCH GOOD AT THIS STAGE OF THE GAME.

KJB

&&

.LONG TERM...
307 PM CDT

TOMORROW THROUGH THURSDAY...

SATURDAY AND SUNDAY...
THE UPPER LEVEL TROUGH PUSHES EAST ALLOWING A LARGE UPPER LEVEL
RIDGE TO MOVE OVERHEAD THROUGH THE WEEKEND. THE CORRESPONDING
SURFACE HIGH MOVES OVER THE REGION TOMORROW EVENING.

GUIDANCE CONTINUES TO FEATURE A NARROW CONVERGENCE BAND ALONG THE
SOUTHWEST END OF LAKE MICHIGAN EARLY SATURDAY MORNING.  KEPT A
SLIGHT CHANCE OF PRECIP IN FOR FAR NORTHEAST IL WITH THE BAND
DISSIPATING BY LATE MORNING/EARLY AFTERNOON AS FORCING AND MOISTURE
WEAKEN. NOT EXPECTING ANY ADDITIONAL SIGNIFICANT ACCUMULATION AND
THE PRECIP TYPE WILL BE A SNOW/RAIN MIX AS TEMPERATURES WILL BE
ABOVE FREEZING OVER THE LAKE.  HAVE MEDIUM CONFIDENCE IN THE BAND
PERSISTING UNTIL MORNING...MEDIUM HIGH CONFIDENCE IN THE BAND MAINLY
IMPACTING THE IL SIDE OF THE LAKE...AND HIGH CONFIDENCE IN LITTLE TO
NO ADDITIONAL ACCUMULATION.

WINDS DECREASE SATURDAY AS THE HIGH MOVES OVERHEAD.  WARMER AIR
BEGINS TO MOVE IN AS WELL WITH HIGHS IN THE LOW 40S TOMORROW. WINDS
TURN SOUTH BEHIND THE HIGH SUNDAY AND USHER IN EVEN WARMER AIR WITH
HIGHS IN THE UPPER 40S TO AROUND 50. SATURDAY AFTERNOON THROUGH
SUNDAY NIGHT WILL BE DRY.

MONDAY THROUGH THURSDAY...
THE RIDGE AXIS MOVES OVERHEAD MONDAY AS THE SURFACE LOW SLIDES OVER
THE SE U.S. THE WARM-UP CONTINUES WITH HIGHS IN THE UPPER 50S TO
AROUND 60 MONDAY...AND MID 50S EXPECTED THROUGH MID WEEK. OVERNIGHT
LOWS VARY FROM THE MID 40S MONDAY NIGHT TO THE MID TO LOWER 30S
THURSDAY NIGHT.

A SURFACE LOW MOVES INTO ONTARIO TUESDAY...AND IT DRAGS A COLD FRONT
ACROSS THE REGION TUESDAY. EXPECTING WIDESPREAD SHOWERS TUESDAY
MORNING WITH RAIN ENDING FROM WEST TO EAST AS THE FRONT SLIDES EAST
TUESDAY EVENING/NIGHT.  GUIDANCE DIFFERS ON HOW MUCH PRECIP WILL
FALL...BUT ITS LOOKING LIKE A GOOD WETTING RAIN IS EXPECTED.

A WEAKER LOW PASSES JUST TO OUR NORTH MID WEEK AND HAVE MEDIUM-LOW
CONFIDENCE IN PRECIP MAKING IT INTO NORTHERN IL WEDNESDAY. THINKING
PRECIP WILL REMAIN CLOSELY TIED TO THE LOW WHICH RIGHT NOW WILL BE
OVER SOUTHERN WI. IF THE LOW/S TRACK WERE TO DIP A BIT MORE
SOUTH...THERE WOULD BE A BETTER CHANCE FOR PRECIP ACROSS FAR
NORTHERN IL.

WINDS TURN NORTHWEST BEHIND THE LOW AND ANOTHER LAKE EFFECT PRECIP
SITUATION IS POSSIBLE FOR NW INDIANA WEDNESDAY NIGHT. ONLY HAVE RAIN
FOR NOW AS TEMPS WILL BE ABOVE FREEZING.  WINDS REMAIN OFF OF THE
LAKE THROUGH THURSDAY NIGHT AS ANOTHER HIGH PRESSURE SYSTEM
APPROACHES FROM THE WEST.

JEE

&&

.AVIATION...

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

* VERY GUSTY NORTH WINDS WITH GUSTS IN EXCESS OF 30 KT INTO EARLY
  EVENING...01-02Z.


* LAKE EFFECT RAIN/SNOW SHOWERS AT MDW WITH OCCASIONAL IFR VIS AT
  MDW THIS AFTERNOON...DRIFTING WEST INTO ORD THIS EVENING.

* INTENSIFYING LAKE EFFECT SNOW SHOWERS PROBABLE OVER MDW LATER
  THIS EVE. SNOW SHOWERS PERSISTING POSSIBLY AS LONG AS EARLY
  SATURDAY MORNING. SNOW SHOWERS POSSIBLE AT ORD.

* CIGS TEMPORARY TO 1500-3000 FT AT MDW LATE THIS AFTERNOON. CIGS
  GRADUALLY LOWERING TO 1500-2500 FT AT BOTH AIRPORTS LATER
  TONIGHT.

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

VERY GUSTY NORTH-NORTHWEST WINDS WILL CONTINUE THROUGH THIS
AFTERNOON AS COLD AIR CONTINUES TO REPLENISH ITSELF. GUSTS OF 33
TO 40 KT...WITH EVEN SPORADICALLY HIGHER ARE HIGHLY LIKELY TO BE
COMMON THROUGH THE AFTERNOON. DURING THE AFTERNOON...DUE TO THE
ORIENTATION OF THE PRESSURE GRADIENT...THE WIND DIRECTION IS
EXPECTED TO SHIFT TO 360 DEGREES AT CHICAGOLAND TAF SITES. LAKE
EFFECT SNOW...MAYBE AT TIMES RAIN...WILL CONTINUE TO IMPACT GARY
THROUGHOUT THIS AFTERNOON AND TONIGHT. WITH SOME BANDING
POTENTIAL THIS EVE VISIBILITY COULD DROP QUITE LOW DURING THAT
PERIOD. THE SNOW BAND...OR AREA OF SHOWERS...WILL BEGIN TO INCH
BACK WESTWARD THIS EVE INTO OVERNIGHT. THE INTENSITY OF SNOW COULD
STILL BE FAIRLY IMPRESSIVE AT MDW LATER THIS EVE...ALTHOUGH A
DECENT AMOUNT OF UNCERTAINTY EXISTS THERE. AT LEAST LAKE-INDUCED
CLOUDS ARE LIKELY OVER NORTHEAST ILLINOIS SATURDAY MORNING
ALTHOUGH THERE COULD CONTINUE SOME SNOW SHOWERS TOO. AT THE SAME
TIME WINDS ARE FAVORED TO BE BETWEEN 360-020 DEGREES...SO IMPACTS
TO ORD OPERATIONS COULD CONTINUE THROUGH SATURDAY MORNING.

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

* HIGH IN WIND SPEEDS AND DIRECTION THROUGH 00Z. MEDIUM THEREAFTER.

* MEDIUM IN HOW FAR VISIBILITY WILL DROP IN SNOW SHOWERS LATE THIS
  AFTERNOON AND EARLY THIS EVE.

* MEDIUM IN SNOW SHOWERS IMPACTING MDW LATER TONIGHT AND LOW FOR
  ORD. LOW IN HOW FAR VISIBILITY WILL DROP AT EITHER AIRPORT.

* MEDIUM IN CIGS THROUGH TAF.

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

* SATURDAY NIGHT...DRY VFR. LIGHT/VARIABLE WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS 10-15 KT.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.
* TUESDAY...SHRA/MVFR LIKELY. SOUTHWEST WINDS.
* WEDNESDAY...DRY/VFR. SOUTHWEST WINDS.
* THURSDAY...DRY/VFR. WEST WINDS.

MTF

&&

.MARINE...
212 PM CDT

STORM FORCE WINDS WILL SLOWLY EASE TO GALES TONIGHT. NO CHANGES
PLANNED TO CURRENT HEADLINES.

FOR THE NEARSHORE ZONES...WILL NEED A PROLONGED SMALL CRAFT ADVISORY
THROUGH AT LEAST SATURDAY AS VERY LARGE WAVES SUBSIDE.  MAY FLIRT
WITH SMALL CRAFT ADVISORY CRITERIA WINDS AND WAVES SUNDAY AND
MONDAY. HAVE MEDIUM CONFIDENCE AS CONDITIONS MAY BE MARGINAL.

NORTH TO NORTHEAST WINDS TO 30 KT SLOWLY DIMINISH SATURDAY AND WINDS
TURN SOUTHWEST BEHIND A HIGH PRESSURE SYSTEM SUNDAY MORNING.  SOUTH
TO SOUTHWEST WINDS INCREASE TO 30 KT SUNDAY AFTERNOON AS THE
GRADIENT TIGHTENS BETWEEN THE DEPARTING HIGH AND AN APPROACHING
LOW.  SOUTH TO SOUTHWEST WINDS FINALLY DIMINISH TO UNDER 30 KT
MONDAY NIGHT...AND THEN WINDS TURN WEST 10-20 KT BEHIND THE LOWS
COLD FRONT TUESDAY. WEST WINDS INCREASE TO 20-25 KT AND BECOME
NORTHWEST WEDNESDAY NIGHT...AND MAY SEE 30 KT WINDS OVER THE
NORTHERN HALF OF THE LAKE THURSDAY.  WINDS DIMINISH THURSDAY NIGHT
AS HIGH PRESSURE MOVES OVER THE AREA.

KJB/JEE

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HIGH WIND WARNING...ILZ014 UNTIL 6 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014 UNTIL 4 AM SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022-ILZ023-
     ILZ033 UNTIL 7 PM FRIDAY.

IN...HIGH WIND WARNING...INZ001-INZ002 UNTIL 6 PM FRIDAY.

     LAKE EFFECT SNOW ADVISORY...INZ001-INZ002-INZ010-INZ011 UNTIL 10
     PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...INZ001-INZ002 UNTIL 4 AM SATURDAY.

     WIND ADVISORY...INZ010-INZ011-INZ019 UNTIL 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 4 AM
     SATURDAY.

     STORM WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563 UNTIL 10 PM FRIDAY.

     GALE WARNING...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 4 AM SATURDAY.

&&

$$

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

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







000
FXUS63 KLOT 312008
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
308 PM CDT FRI OCT 31 2014

.SHORT TERM...
307 PM CDT

THROUGH TONIGHT...

NO CHANGES PLANNED WITH HEADLINES.

SEVERAL BANDS OF LAKE EFFECT SNOW HAVE DEVELOPED ACROSS SOUTHERN
LAKE MICHIGAN EARLY THIS AFTERNOON...WITH SOME OF THESE SNOW SHOWERS
IMPACTING PORTIONS OF THE NORTHEASTERN ILLINOIS SHORES.
HOWEVER...THE MOST SUBSTANTIAL AREA OF LAKE EFFECT RAIN AND SNOW HAS
BEEN OCCURRING ALONG THE SOUTHERN TIP OF LAKE MICHIGAN AND ACROSS THE
ADVISORY AREA OF NORTHWESTERN INDIANA. BASED ON NUMEROUS PHONE
CALLS ACROSS THIS AREA IT APPEARS AREAS NEAR THE LAKE ARE SLIGHTLY
WARMER...RESULTING IN A RAIN SNOW MIX. HOWEVER...AREAS ROUGHLY 20 TO
30 MILES INLAND (BASICALLY ALONG AND SOUTH OF A CROWN POINT TO
VALPARAISO INDIANA LINE) THE PRECIPITATION IS MAINLY IN THE FORM OF
SNOW. SEVERAL REPORTS OF ACCUMULATING SNOW HAVE BEEN RECEIVED SOUTH
OF THIS LINE...WITH LOW VISIBILITIES UNDER A MILE.

BASED ON CURRENT RADAR TRENDS AND SHORT RANGE HIRES GUIDANCE...IT
APPEARS THIS ACTIVITY WILL CONTINUE TO BE FOCUSED MAINLY ACROSS
NORTHWESTERN INDIANA FOR THE NEXT FEW HOURS...THROUGH LATE
AFTERNOON/EARLY THIS EVENING. HOWEVER...SOME OF THE LESS ORGANIZED LAKE
EFFECT SNOW SHOWERS WILL LIKELY IMPACT PORTIONS OF COOK AND LAKE
COUNTIES IN ILLINOIS AS WELL DURING THIS TIME. FINALLY...AS THE
SURFACE LOW SHIFTS SOUTHEAST OVER THE OHIO VALLEY INTO THIS EVENING
THE BOUNDARY LAYER FLOW WILL VEER AND WEAKEN A BIT. THIS SHOULD
ALLOW THE BETTER FOCUS FOR LAKE EFFECT SHOWERS TO SHIFT FARTHER WEST
ACROSS PORTIONS OF EASTERN ILLINOIS...INCLUDING THE CHICAGO METRO
AREA NEAR THE LAKE. WHILE THERE COULD BE A SHORT PERIOD OF SOME
MODERATE...OR EVEN BRIEFLY HEAVY SNOW SHOWERS INTO NORTHEASTERN
ILLINOIS INTO THIS EVENING...I HAVE CHOSEN NOT TO EXTEND THE WINTER
ADVISORIES FARTHER WEST INTO ILLINOIS. THIS IS MAINLY DUE TO THE
FACT THAT IT APPEARS THE THREAT FOR BETTER MORE ORGANIZED LAKE
EFFECT SNOW WILL BE OF SHORT DURATION...LIMITING OVERALL
ACCUMULATIONS. HEIGHT RISES AND WARMING TEMPERATURES IN THE MID
LEVELS SHOULD ALLOW INVERSION HEIGHTS TO DROP BELOW THE DENDRITIC
GROWTH ZONE BY LATER THIS EVENING/OVERNIGHT. THE MODELS HAVE BEEN
INSISTENT ON THIS FOR THE PAST FEW DAYS AND SEE NO REASON WHY THIS
WOULD NOT OCCUR AS THE UPPER RIDGE TO OUR WEST BEGINS TO BUILD
EASTWARD. THEREFORE...ANY LEFT OVER LAKE EFFECT SNOW SHOWERS WILL
LIKELY NOT BE EFFICIENT SNOWFALL PRODUCERS AND LIKELY BE LOOSELY
ORGANIZED...AND HENCE THE THREAT FOR ACCUMULATING SNOWFALL SHOULD
COME TO AN END BY LATER THIS EVENING.

THE WINDS WITH THIS SYSTEM HAVE BEEN IMPRESSIVE. KGYY HAS BEEN
EXPERIENCING GUSTS TO 58 KT FOR SEVERAL HOURS...WITH SIMILAR
MAGNITUDES NOTED ALONG THE LAKE SHORE. IT APPEARS THESE STRONG WINDS
WILL SLOWLY EASE TONIGHT AS THE SURFACE HIGH OVERSPREADS THE AREA ON
SATURDAY. THEREFORE...NO CHANGES ARE PLANNED WITH THE CURRENT WIND
ADVISORIES OR WARNINGS.

LAKE SHORE FLOODING CONTINUES TO BE AN ISSUE...ESPECIALLY IN
CHICAGO...WHERE WAVES HAVE BEEN GETTING WATER ONTO LAKE SHORE DRIVE.
WE CONSIDERED TO UPGRADE TO A LAKE SHORE FLOOD WARNING...BUT DECIDED
TO JUST BEEF UP THE WORDING IN THE CURRENT ADVISORY AS A WARNING
WOULD NOT DUE MUCH GOOD AT THIS STAGE OF THE GAME.

KJB

&&

.LONG TERM...
307 PM CDT

TOMORROW THROUGH THURSDAY...

SATURDAY AND SUNDAY...
THE UPPER LEVEL TROUGH PUSHES EAST ALLOWING A LARGE UPPER LEVEL
RIDGE TO MOVE OVERHEAD THROUGH THE WEEKEND. THE CORRESPONDING
SURFACE HIGH MOVES OVER THE REGION TOMORROW EVENING.

GUIDANCE CONTINUES TO FEATURE A NARROW CONVERGENCE BAND ALONG THE
SOUTHWEST END OF LAKE MICHIGAN EARLY SATURDAY MORNING.  KEPT A
SLIGHT CHANCE OF PRECIP IN FOR FAR NORTHEAST IL WITH THE BAND
DISSIPATING BY LATE MORNING/EARLY AFTERNOON AS FORCING AND MOISTURE
WEAKEN. NOT EXPECTING ANY ADDITIONAL SIGNIFICANT ACCUMULATION AND
THE PRECIP TYPE WILL BE A SNOW/RAIN MIX AS TEMPERATURES WILL BE
ABOVE FREEZING OVER THE LAKE.  HAVE MEDIUM CONFIDENCE IN THE BAND
PERSISTING UNTIL MORNING...MEDIUM HIGH CONFIDENCE IN THE BAND MAINLY
IMPACTING THE IL SIDE OF THE LAKE...AND HIGH CONFIDENCE IN LITTLE TO
NO ADDITIONAL ACCUMULATION.

WINDS DECREASE SATURDAY AS THE HIGH MOVES OVERHEAD.  WARMER AIR
BEGINS TO MOVE IN AS WELL WITH HIGHS IN THE LOW 40S TOMORROW. WINDS
TURN SOUTH BEHIND THE HIGH SUNDAY AND USHER IN EVEN WARMER AIR WITH
HIGHS IN THE UPPER 40S TO AROUND 50. SATURDAY AFTERNOON THROUGH
SUNDAY NIGHT WILL BE DRY.

MONDAY THROUGH THURSDAY...
THE RIDGE AXIS MOVES OVERHEAD MONDAY AS THE SURFACE LOW SLIDES OVER
THE SE U.S. THE WARM-UP CONTINUES WITH HIGHS IN THE UPPER 50S TO
AROUND 60 MONDAY...AND MID 50S EXPECTED THROUGH MID WEEK. OVERNIGHT
LOWS VARY FROM THE MID 40S MONDAY NIGHT TO THE MID TO LOWER 30S
THURSDAY NIGHT.

A SURFACE LOW MOVES INTO ONTARIO TUESDAY...AND IT DRAGS A COLD FRONT
ACROSS THE REGION TUESDAY. EXPECTING WIDESPREAD SHOWERS TUESDAY
MORNING WITH RAIN ENDING FROM WEST TO EAST AS THE FRONT SLIDES EAST
TUESDAY EVENING/NIGHT.  GUIDANCE DIFFERS ON HOW MUCH PRECIP WILL
FALL...BUT ITS LOOKING LIKE A GOOD WETTING RAIN IS EXPECTED.

A WEAKER LOW PASSES JUST TO OUR NORTH MID WEEK AND HAVE MEDIUM-LOW
CONFIDENCE IN PRECIP MAKING IT INTO NORTHERN IL WEDNESDAY. THINKING
PRECIP WILL REMAIN CLOSELY TIED TO THE LOW WHICH RIGHT NOW WILL BE
OVER SOUTHERN WI. IF THE LOW/S TRACK WERE TO DIP A BIT MORE
SOUTH...THERE WOULD BE A BETTER CHANCE FOR PRECIP ACROSS FAR
NORTHERN IL.

WINDS TURN NORTHWEST BEHIND THE LOW AND ANOTHER LAKE EFFECT PRECIP
SITUATION IS POSSIBLE FOR NW INDIANA WEDNESDAY NIGHT. ONLY HAVE RAIN
FOR NOW AS TEMPS WILL BE ABOVE FREEZING.  WINDS REMAIN OFF OF THE
LAKE THROUGH THURSDAY NIGHT AS ANOTHER HIGH PRESSURE SYSTEM
APPROACHES FROM THE WEST.


JEE

&&

.AVIATION...

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

* VERY GUSTY NORTH-NORTHWEST WINDS GRADUALLY SHIFTING TO DUE NORTH
  BY LATE AFTERNOON. SPORADIC GUSTS IN EXCESS OF 40 KT THROUGH
  22Z.

* LIKELIHOOD FOR PERIODIC LAKE EFFECT RAIN/SNOW SHOWERS AT MDW
  THROUGH THE REST OF THE AFTERNOON AND EARLY EVE...POSSIBLE AT
  ORD.

* INTENSIFYING LAKE EFFECT SNOW SHOWERS PROBABLE OVER MDW LATER
  THIS EVE. SNOW SHOWERS PERSISTING POSSIBLY AS LONG AS EARLY
  SATURDAY MORNING. SNOW SHOWERS POSSIBLE AT ORD.

* CIGS TEMPORARY TO 1500-3000 FT AT MDW THIS AFTERNOON. CIGS
  GRADUALLY LOWERING TO 1500-2500 FT AT BOTH AIRPORTS LATER
  TONIGHT.


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

VERY GUSTY NORTH-NORTHWEST WINDS WILL CONTINUE THROUGH THIS
AFTERNOON AS COLD AIR CONTINUES TO REPLENISH ITSELF. GUSTS OF 33
TO 40 KT...WITH EVEN SPORADICALLY HIGHER ARE HIGHLY LIKELY TO BE
COMMON THROUGH THE AFTERNOON. DURING THE AFTERNOON...DUE TO THE
ORIENTATION OF THE PRESSURE GRADIENT...THE WIND DIRECTION IS
EXPECTED TO SHIFT TO 360 DEGREES AT CHICAGOLAND TAF SITES. LAKE
EFFECT SNOW...MAYBE AT TIMES RAIN...WILL CONTINUE TO IMPACT GARY
THROUGHOUT THIS AFTERNOON AND TONIGHT. WITH SOME BANDING
POTENTIAL THIS EVE VISIBILITY COULD DROP QUITE LOW DURING THAT
PERIOD. THE SNOW BAND...OR AREA OF SHOWERS...WILL BEGIN TO INCH
BACK WESTWARD THIS EVE INTO OVERNIGHT. THE INTENSITY OF SNOW COULD
STILL BE FAIRLY IMPRESSIVE AT MDW LATER THIS EVE...ALTHOUGH A
DECENT AMOUNT OF UNCERTAINTY EXISTS THERE. AT LEAST LAKE-INDUCED
CLOUDS ARE LIKELY OVER NORTHEAST ILLINOIS SATURDAY MORNING
ALTHOUGH THERE COULD CONTINUE SOME SNOW SHOWERS TOO. AT THE SAME
TIME WINDS ARE FAVORED TO BE BETWEEN 360-020 DEGREES...SO IMPACTS
TO ORD OPERATIONS COULD CONTINUE THROUGH SATURDAY MORNING.


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

* HIGH IN WIND SPEEDS AND DIRECTION THROUGH 00Z. MEDIUM THEREAFTER.

* MEDIUM IN HOW FAR VISIBILITY WILL DROP IN SNOW SHOWERS LATE THIS
  AFTERNOON AND EARLY THIS EVE.

* MEDIUM IN SNOW SHOWERS IMPACTING MDW LATER TONIGHT AND LOW FOR
  ORD. LOW IN HOW FAR VISIBILITY WILL DROP AT EITHER AIRPORT.

* MEDIUM IN CIGS THROUGH TAF.


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

* SATURDAY NIGHT...DRY VFR. LIGHT/VARIABLE WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS 10-15 KT.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.
* TUESDAY...SHRA/MVFR LIKELY. SOUTHWEST WINDS.
* WEDNESDAY...DRY/VFR. SOUTHWEST WINDS.
* THURSDAY...DRY/VFR. WEST WINDS.

MTF

&&

.MARINE...
212 PM CDT

STORM FORCE WINDS WILL SLOWLY EASE TO GALES TONIGHT. NO CHANGES
PLANNED TO CURRENT HEADLINES.

FOR THE NEARSHORE ZONES...WILL NEED A PROLONGED SMALL CRAFT ADVISORY
THROUGH AT LEAST SATURDAY AS VERY LARGE WAVES SUBSIDE.  MAY FLIRT
WITH SMALL CRAFT ADVISORY CRITERIA WINDS AND WAVES SUNDAY AND
MONDAY. HAVE MEDIUM CONFIDENCE AS CONDITIONS MAY BE MARGINAL.

NORTH TO NORTHEAST WINDS TO 30 KT SLOWLY DIMINISH SATURDAY AND WINDS
TURN SOUTHWEST BEHIND A HIGH PRESSURE SYSTEM SUNDAY MORNING.  SOUTH
TO SOUTHWEST WINDS INCREASE TO 30 KT SUNDAY AFTERNOON AS THE
GRADIENT TIGHTENS BETWEEN THE DEPARTING HIGH AND AN APPROACHING
LOW.  SOUTH TO SOUTHWEST WINDS FINALLY DIMINISH TO UNDER 30 KT
MONDAY NIGHT...AND THEN WINDS TURN WEST 10-20 KT BEHIND THE LOWS
COLD FRONT TUESDAY. WEST WINDS INCREASE TO 20-25 KT AND BECOME
NORTHWEST WEDNESDAY NIGHT...AND MAY SEE 30 KT WINDS OVER THE
NORTHERN HALF OF THE LAKE THURSDAY.  WINDS DIMINISH THURSDAY NIGHT
AS HIGH PRESSURE MOVES OVER THE AREA.

KJB/JEE

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HIGH WIND WARNING...ILZ014 UNTIL 6 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014 UNTIL 4 AM SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022-ILZ023-
     ILZ033 UNTIL 7 PM FRIDAY.

IN...HIGH WIND WARNING...INZ001-INZ002 UNTIL 6 PM FRIDAY.

     LAKE EFFECT SNOW ADVISORY...INZ001-INZ002-INZ010-INZ011 UNTIL 10
     PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...INZ001-INZ002 UNTIL 4 AM SATURDAY.

     WIND ADVISORY...INZ010-INZ011-INZ019 UNTIL 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 PM FRIDAY TO
     4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563 UNTIL 10 PM FRIDAY.

     GALE WARNING...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 4 AM SATURDAY.

&&

$$

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

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










000
FXUS63 KILX 312005
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
305 PM CDT Fri Oct 31 2014

.SHORT TERM...(Tonight)
ISSUED AT 304 PM CDT FRI OCT 31 2014

Increased pressure gradient behind the cold front has created a
blustery day across Central Illinois.  In combination with colder
air moving into the region, wind chills are dropping in the 30s.
Although the winds are expected to slowly decrease after sunset...it
will be very slow and accompanied by dropping temperatures as well.
As a result, going into Halloween night, trick or treaters will
encounter temperatures in the upper 30s and lower 40s...with winds
still in the 20 to 25 mph range and occasionally very gusty early.
Wind chills at or below freezing for the few hours around sunset.
Temperatures tonight will drop mainly into the 20s and provide a
significant hard freeze for the end of October.  Though there is
some spread in the MOS for this event, vast majority keep the 20s in
place.  Some remaining lake effect snow/rain will dwindle into the
overnight hours, mainly impacting the extreme eastern IL/IN border
with flurries and light rain.  Accumulations are not expected.


&&

.LONG TERM...(Saturday through Friday)
ISSUED AT 304 PM CDT FRI OCT 31 2014

Cold high pressure will settle over Illinois during the day Saturday
bringing much lighter winds, continuing through Saturday night. The
light winds and dry air mass will allow for another night of sub
freezing temperatures due to good radiational cooling. Temperatures
will moderate somewhat Sunday, but still remain much below average
with highs mainly in the upper 40s.

More unsettled weather is on track Monday to Wednesday as moist
southwesterly flow develops ahead of a strong upper level trough
digging into the southern Rockies. A frontal boundary will set up
from the southern Plains NE into the Ohio river valley Monday night
through Wed to bring chances for showers, especially Monday night
and Tuesday. Milder temperatures can be expected in this time
period, with highs in the upper 50s and lows mainly in the 40s.
Model data indicates weak instability with this system, meaning
thunderstorms are unlikely. Drier weather is expected Wed night thru
Friday as dry west northwesterly flow trails the system. Expect
seasonable highs generally in the mid to upper 50s.


&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1243 PM CDT FRI OCT 31 2014
VFR throughout. Main issue is the wind today. North/northwest,
23 to 28 kts sustained, and gusting in excess of 35 kts. Ceilings
confined to mainly the eastern half of the state, DEC, CMI and BMI
at this point between 3500-4000 ft. Lake effect showers streaming
into far eastern portions of the state...but just east of CMI so
far. Winds expected to ease somewhat going into the overnight...as
the atmosphere decouples and lose the gusts from mid levels.
Although the winds will decrease in the overnight, they will still
be in the 15-20kt range for much of the evening...and 10-15kt
after 06z. Current cloud cover has a strong diurnal component to
what is left from the frontal passage, and expect the clouds to
scatter out just before sunset in ILX terminals, save CMI where
the lake effect showers likely to keep clouds over to the east a
bit longer into the overnight.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING from Midnight tonight to 9 AM CDT Saturday FOR
ILZ027>031-036>038-040>057-061>063-066>068-071>073.

&&

$$

SHORT TERM...HJS
LONG TERM...Onton
AVIATION...HJS







000
FXUS63 KLOT 311804
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
104 PM CDT FRI OCT 31 2014

.MESOSCALE DISCUSSION...

WE ARE CURRENTLY WATCHING THE PROGRESS OF A SECONDARY INVERTED
SURFACE TROUGH...WHICH IS CURRENTLY RACING SOUTHWARD DOWN CENTRAL
LAKE MICHIGAN. OBSERVATIONS OVER AND NEAR THE LAKE INDICATE THE
PRESENCE OF GOOD CONVERGENCE ALONG THIS BOUNDARY. THE FIRST
MORNING VISIBLE SATELLITE IMAGES ALSO INDICATE CONVECTIVE
STRUCTURES DEVELOPING WITHIN THE BAND OF RAIN/SNOW SHOWERS
CURRENTLY SHIFTING SOUTHWARD JUST EAST OF MKE. OVERALL IT APPEARS
THIS AREA OF SNOWFALL WILL PIVOT SOUTHWARD ACROSS NORTHWESTERN
INDIANA WITHIN THE NEXT 2 HOURS (BY 1630Z). HOWEVER...I AM ALSO
CONCERNED THAT SOME OF THESE HEAVIER CONVECTIVE SNOW SHOWERS MAY
IMPACT PORTIONS OF NORTHEASTERN ILLINOIS...INCLUDING DOWNTOWN
CHICAGO THROUGH LATE MORNING. IN FACT...SOME OF THE LATEST RADAR
IMAGERY IS ALREADY INDICATING SOME BANDS OF PRECIP MOVING INTO
NORTHERN COOK COUNTY. IT APPEARS THE WINDS WILL BECOME MORE
NORTHERLY IN THE WAKE OF THIS SURFACE TROUGH...AND WIND SPEEDS
COULD ALSO INCREASE A BIT HIGHER THAN CURRENT WIND SPEEDS. WE WILL
CONTINUE TO WATCH OBSERVATION TRENDS...AND HANDLE THIS SNOWFALL
ACROSS THE CHICAGO AREA WITH GRAPHICAL NOWCASTS AT THIS TIME. IT
DOES APPEAR THIS INITIAL BURST OF SNOW WILL BE SOMEWHAT SHORT
LIVED ACROSS THE CHICAGO METRO AREA. WHILE SOME MINOR
ACCUMULATIONS ARE CERTAINLY POSSIBLE WITH THIS ACTIVITY...WE HAVE
NO IMMEDIATE PLANS TO EXPAND THE CURRENT WINTER WEATHER HEADLINES.

FOLLOWING THIS INITIAL BOUNDARY AND BURST OF SNOW...HI RES GUIDANCE
CONTINUES TO INDICATE THAT BANDS OF LAKE EFFECT RAIN/SNOW SHOWERS
WILL CONTINUE TO DEVELOP AND IMPACT MUCH OF THE AREAS CURRENTLY
UNDER THE WINTER HEADLINE ACROSS NORTHWESTERN INDIANA. HOWEVER...WE
WILL NEED TO WATCH FOR THE POTENTIAL OF THE LAKE EFFECT BANDS THIS
AFTERNOON TRYING TO WORK MORE WEST INTO EASTERN ILLINOIS. SOME
GUIDANCE DOES SUGGEST THAT THE LAKE EFFECT BANDS WILL EFFECT AREAS
NEAR...OR EVEN ALONG THE ILLINOIS...INDIANA STATE LINE....AND
POSSIBLY PARTS OF CHICAGO AS WELL. HOWEVER...GIVEN THE MODEL
DIFFERENCES...AND UNCERTAINTY STILL INHERENT IN WHERE ANY LAKE EFFECT
BAND...OR BANDS WILL SET UP...I WOULD LIKE TO WATCH THE EVOLUTION OF
CONDITIONS OVER THE LAKE BEFORE PUSHING SNOWFALL AMOUNTS...AND WINTER
HEADLINES FARTHER WEST.

NO BIG CHANGES ARE PLANNED FOR THE UPDATE. HOWEVER...I WILL LIKELY
ADD A MENTION OF LIGHT SNOW/FLURRIES FOR AREAS A BIT FARTHER INLAND
ACROSS NORTHEASTERN ILLINOIS BASED ON REPORTS OF LIGHT SNOW...AND
RADAR TRENDS.

KJB

&&

.SHORT TERM...
326 AM CDT

THROUGH SATURDAY...

ACTIVE WEATHER ON TAP THE NEXT 24 HOURS AS COMPACT AND DEEP UPPER
LOW DIVES SOUTH ACROSS THE REGION DRAGGING UNSEASONABLY COLD
AIR...BOTH AT THE SURFACE AND ALOFT...INTO THE REGION TODAY INTO
TONIGHT. EARLY THIS MORNING SURFACE ANALYSIS SHOWS A RATHER DIFFUSE
COLD FRONT MOVING ACROSS THE REGION WITH STRONG COLD ADVECTION
RESULTING IN A HEALTHY TEMP DROP PRIOR TO SUNRISE OVER NORTHERN CWA
AND SHORTLY AFTERWARD SOUTHEAST. STRONG NNW WINDS WILL ALSO ARRIVE
WITH THE COLD AIR AND CONTINUE INTO THIS EVENING RESULTING IN
TEMPERATURES LARGELY REMAINING FAIRLY STEADY THROUGH THE AFTERNOON.

COMPACT VORT AND REALLY THE HEART OF THE UPPER LOW SHOWS UP NICELY
OVER NORTHERN WISCONSIN EARLY THIS MORNING AND IS DIVING SSE TOWARD
THE AREA. THE COMBINATION OF ASCENT WITH THIS FEATURE AND STEEP
LAPSE RATES ARE RESULTING IN SCATTERED BUT FAIRLY VIGOROUS SNOW
SHOWERS OVER NORTHERN AND CENTRAL WISCONSIN AND WOULD FULLY
ANTICIPATE THESE TO MAINTAIN THEMSELVES AND MOVE ACROSS MAINLY THE
EASTERN CWA THIS MORNING. TEMPS WILL PROBABLY BE TOO WARM FOR MUCH
IF ANY ACCUMULATION...BUT SOME OF THE SNOW SHOWERS COULD BE BRIEFLY
VIGOROUS AND KNOCK VSBY DOWN TO BELOW 1SM. AS THE VORT CONTINUE
SOUTHEAST LOOK FOR THE NON-LAKE DRIVEN PRECIP TO END BY MID MORNING
NORTHERN CWA AND LATE MORNING SOUTHEAST CWA.

THE VORT WILL HERALD THE ARRIVAL OF THE COLDEST AIR ALOFT AND
RESULTANT STRONGEST INSTABILITY OVER THE LAKE AS H5 TEMPS DROP TO
-33C AND H7 TEMPS BELOW -15C. THERMODYNAMIC PROFILES OVER THE LAKE
BEHIND THIS VORT BECOME EXPLOSIVELY UNSTABLE THIS MORNING REMAIN SO
THROUGH THE DAY. LAKE EFFECT SHOULD GET GOING IN ERNEST BEHIND THIS
VORT AND CONTINUE TO SOME DEGREE INTO SATURDAY MORNING. FORECAST
LAKE INDUCED EQUILIBRIUM LEVELS TODAY APPROACH 20K FT...NEAR THE
-30C LEVEL...WHICH IS MORE THAN COLD ENOUGH TO SUPPORT LIGHTNING
GIVEN THE HIGH LIKELIHOOD OF MIXED PHASE HYDROMETEORS (SUPERCOOLED
DROPLETS AND ICE) IN THE CLOUDS WITHIN STRONG UPDRAFTS. NEAR SURFACE
TEMPS OVER THE LAKE AND WITHIN A FEW MILES OF THE LAKE SHORE MAY BE
WARM ENOUGH TO SUPPORT P-TYPE FLUCTUATING BETWEEN RAIN...RAIN/SNOW
MIX...AND ALL SNOW. LAKE EFFECT PRECIP FARTHER INLAND STANDS A MUCH
BETTER CHANCE OF REMAINING ALL OR MOSTLY SNOW.

ONE OF THE BIGGER UNCERTAINTIES FOR TODAY IS HOW ORGANIZED THE LAKE
EFFECT WILL BECOME AND WHETHER IT WILL BE MULTIPLE BANDS OR A SINGLE
INTENSE BAND. GIVEN THE VERY STRONG BOUNDARY LAYER WINDS AND LESS
THAN IDEAL TIME OF DAY AM CONCERNED THAT THE LAKE EFFECT PRECIP
COULD BE SOMEWHAT UNORGANIZED/SCATTERED IN NATURE WITH MULTIPLE
BANDS DURING THE DAY WHICH WILL BE THE TIME OF STRONG TO EXTREME
INSTABILITY. IF A MORE ORGANIZED DOMINANT SINGLE BAND DOES
FORM...THE STRONG FLOW AND INSTABILITY WELL INLAND WOULD SUPPORT
INTENSE PRECIP RATES MAKING IT WELL INLAND THIS AFTERNOON WHERE
P-TYPE WOULD LIKELY BE MOSTLY SNOW...POSSIBLY MODERATE TO HEAVY
SNOW. IF SNOW FALLS HEAVY ENOUGH THEN THE WARM GROUND TEMPS WOULD
BECOME MORE OF A MOOT POINT WITH RAPID ACCUMULATIONS OF HEAVY/WET
SNOW...ESPECIALLY ON GRASSY SURFACES WHERE ISOLATED LOCATIONS COULD
SEE A QUICK SEVERAL INCHES OF SNOW. THE MOST LIKELY SCENARIO WOULD
APPEAR TO BE SOMEWHAT LESS ORGANIZED BANDS OF SNOW SHOWERS RESULTING
IN ONLY MINOR ACCUMS ON GRASSY SURFACES IN SPOTS TODAY. THE WIND
WILL BE WHIPPING THE SNOW AROUND REGARDLESS SO UNDERNEATH ANY LAKE
EFFECT SNOW CONDITIONS WILL BE PRETTY MISERABLE EVEN THOUGH IT IS
UNLIKELY TO ACCUMULATE ON ROADS/SIDEWALKS TODAY. LAKE AND PORTER
COUNTY LOOK TO BE GROUND ZERO FOR THE LAKE EFFECT TODAY WITH THE
PRECIP LIKELY MAKING IT WELL INLAND TO JASPER AND NEWTON COUNTIES.
SOME HIGH RES GUIDANCE DOES CLIP SE COOK AND EASTERN WILL WITH LAKE
EFFECT PRECIP TODAY WHICH ISNT OUT OF THE QUESTION AND HAVE
MAINTAINED LOW POPS THERE.

THIS EVENING THE LOW LEVEL FLOW WILL GRADUALLY VEER AND SEND THE
LAKE EFFECT MORE INTO EASTERN COOK/EASTERN WILL/WESTERN LAKE IN (AND
EVEN POINTS SOUTH. BY THIS EVENING THE BOUNDARY LAYER FLOW WILL BE
WEAKENING AND THE TEMPS OUTSIDE OF THE LAKE INFLUENCED AREAS
DROPPING WHICH WOULD BOTH TEND TO FAVOR A TRANSITION TO A MORE
ORGANIZED DOMINANT SINGLE LAKE EFFECT BAND. MY BEST GUESS IS THAT
THE TIME WINDOW FOR THE HIGHEST PROBABILITY OF A DOMINANT LAKE
EFFECT BAND WITH POTENTIAL FOR HEAVY SNOW IS BETWEEN 23Z AND ABOUT
04Z. DURING THIS TIME PERIOD THE INSTABILITY (WHILE LESS THAN
EARLIER IN THE DAY) WILL STILL BE STRONG WITH INVERSION HEIGHTS
AROUND 10K FT AND LAKE-850 DELTA T VALUES >20C. DOES APPEARS A
PERIOD OF HEAVY SNOW COULD OCCUR IN EASTERN/SOUTHEASTERN COOK AND
EASTERN WILL COUNTIES EARLY THIS EVENING...BUT GIVEN THE LOW
CONFIDENCE OPTED NOT TO EXPAND THE WINTER WX HEADLINES AT THIS TIME
AND INSTEAD WILL ALLOW DAY SHIFT TO MONITOR MESOSCALE TRENDS. BY
LATER THIS EVENING INTO THE OVERNIGHT HOURS THE LAKE EFFECT
PARAMETERS WILL CONTINUE TO BECOME LESS FAVORABLE AND THE INTENSITY
OF THE LAKE EFFECT PRECIP SHOULD BEGIN TO WIND DOWN LATE TONIGHT AND
EVENTUALLY END SATURDAY. HAVE EXTENDED THE HIGHER POPS LATER IN TIME
AS LAKE EFFECT RARELY WINDS DOWN AS QUICKLY AS MODEL PROGGED
PARAMETERS SUGGEST IT WILL. WORTH NOTING THAT BY LATE EVENING AND
THROUGH SAT MORNING THE CONVECTIVE CLOUD TOP TEMPS DROP BELOW -12C
MEANING THE LIKELIHOOD OF CLOUDS CONTAINING ICE NUCLEI FOR SNOW WILL
BE LOW...SO DESPITE LOWER TEMPS IN THE BOUNDARY LAYER HAVE
TRANSITIONED P-TYPE BACK TO RAIN OR SNOW LATE TONIGHT AND SAT
MORNING.

FINALLY...HIGH WINDS WILL BE THE OTHER CONCERN TODAY. PLAN TO
MAINTAIN WIND ADVISORY AS IS THOUGH CONFIDENCE IN INLAND LOCATIONS
REACHING ADVISORY CRITERIA IS NOT THAT HIGH...BUT WITH GUSTS TO AT
LEAST 40 MPH A GOOD BET NOTHING WOULD BE GAINED FROM MAKING ANY
CHANGES TO THE HEADLINES. THE STORM WARNING FOR THE LAKE LOOKS
LIKELY TO VERIFY WITH 40 MPH SUSTAINED AND POSSIBLY GUSTS TO 58 MPH
LIKELY ALONG THE LAKE FRONT TODAY AND REALLY NOT COMFORTABLE NOT
HAVING A WARNING WITH THE POTENTIAL FOR DAMAGING WINDS ALONG THE
LAKE...SO AM GOING TO UPGRADE TO A HIGH WIND WARNING FOR LAKE SHORE
AREAS.

HEADLINES ARE AN ABSOLUTE MESS AND HEADACHE. WINTER WX ADVISORY
COVERS WIND AND SNOW...BUT IN ORDER TO GO WITH WARNING FOR WIND
ALONG THE LAKE FRONT IN INDIANA WOULD NEED TO UPGRADE TO A WINTER
STORM WARNING WHICH REALLY DOESNT SEEM TO BE THE BEST PRODUCT. AFTER
MUCH HEMMING AND HAWING AND INTERNAL COORDINATION HAVE OPTED TO
CHANGE THE WINTER WX ADV TO A LAKE EFFECT SNOW ADVISORY AND ISSUE A
WIND ADVISORY FOR JASPER AND NEWTON AND A HIGH WIND WARNING FOR LAKE
SHORE AREAS OF COOK...PORTER...AND LAKE IN. MAY NEED TO REPLACE THE
HIGH WIND WARNING WITH A WIND ADVISORY BY EARLY EVENING FOR

IZZI

&&

.LONG TERM...
325 AM CDT

SATURDAY NIGHT THROUGH THURSDAY...

MUCH...MUCH QUIETER SUNDAY AND MONDAY WITH MODERATING TEMPS. SLOW
MOVING FRONT COULD BRING A SOMEWHAT PROLONGED PERIOD OF RAIN/SHOWERS
MONDAY NIGHT THOUGH TUESDAY NIGHT. GENERALLY SEASONABLE TEMPS
EXPECTED THROUGH THE EXTENDED.

IZZI

&&

.AVIATION...

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

* VERY GUSTY NORTH-NORTHWEST WINDS GRADUALLY SHIFTING TO DUE NORTH
  BY MID-AFTERNOON. SPORADIC GUSTS IN EXCESS OF 40 KT THROUGH 22Z.

* PERIODS OF FLURRIES THIS AFTERNOON WITH THE POTENTIAL FOR SOME
  TEMPORARY SNOW SHOWERS NAMELY AT MDW.

* LAKE EFFECT SNOW SHOWERS PROBABLE OVER MDW LATER THIS EVE
  THROUGH EARLY SATURDAY MORNING AND ORD OVERNIGHT INTO EARLY
  SATURDAY MORNING.

* CIGS DROPPING TO 1500-3000 FT LATER THIS EVENING THROUGH EARLY
  SATURDAY MORNING.


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

VERY GUSTY NORTH-NORTHWEST WINDS WILL CONTINUE THROUGH THIS
AFTERNOON AS COLD AIR CONTINUES TO REPLENISH ITSELF. GUSTS OF 33
TO 40 KT...WITH EVEN SPORADICALLY HIGHER ARE HIGHLY LIKELY TO BE
COMMON THROUGH THE AFTERNOON. DURING THE AFTERNOON...DUE TO THE
ORIENTATION OF THE PRESSURE GRADIENT...THE WIND DIRECTION IS
EXPECTED TO SHIFT TO 360 DEGREES AT CHICAGOLAND TAF SITES. LAKE
EFFECT SNOW...MAYBE AT TIMES RAIN...WILL CONTINUE TO IMPACT GARY
THROUGHOUT THIS AFTERNOON AND TONIGHT. WITH SOME BANDING
POTENTIAL THIS EVE VISIBILITY COULD DROP QUITE LOW DURING THAT
PERIOD. THE SNOW BAND...OR AREA OF SHOWERS...WILL BEGIN TO INCH
BACK WESTWARD THIS EVE INTO OVERNIGHT. THE INTENSITY OF SNOW COULD
STILL BE FAIRLY IMPRESSIVE AT MDW LATER THIS EVE...ALTHOUGH A
DECENT AMOUNT OF UNCERTAINTY EXISTS THERE. AT LEAST LAKE-INDUCED
CLOUDS ARE LIKELY OVER NORTHEAST ILLINOIS SATURDAY MORNING
ALTHOUGH THERE COULD CONTINUE SOME SNOW SHOWERS TOO. AT THE SAME
TIME WINDS ARE FAVORED TO BE BETWEEN 360-020 DEGREES...SO IMPACTS
TO ORD OPERATIONS COULD CONTINUE THROUGH SATURDAY MORNING.


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

* HIGH IN WIND SPEEDS AND HIGH THAT DIRECTION WILL SHIFT TO 360
  DEGREES THIS AFTERNOON. MEDIUM NORTH-NORTHEAST ON SATURDAY
  MORNING.

* HIGH THAT ANY REDUCTION IN VISIBILITY IN SNOW PRIOR TO 02Z WOULD
  BE VERY BRIEF.

* MEDIUM IN SNOW SHOWERS IMPACTING MDW LATER TONIGHT AND LOW FOR
  ORD. LOW IN HOW LOW VISIBILITY WILL DROP AT EITHER AIRPORT.

* MEDIUM IN CIGS THROUGH TAF.


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

* SATURDAY NIGHT...DRY VFR. LIGHT/VARIABLE WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS 10-15 KT.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.
* TUESDAY...SHRA/MVFR LIKELY. SOUTHWEST WINDS.
* WEDNESDAY...DRY/VFR. SOUTHWEST WINDS.
* THURSDAY...DRY/VFR. WEST WINDS.

MTF

&&

.MARINE...
256 AM CDT

A MAJOR WIND EVENT CONTINUES TO TAKE SHAPE FOR LAKE MICHIGAN EARLY
THIS MORNING. FAIRLY BROAD LOW PRESSURE OVER LAKE HURON WILL TRACK
SOUTHEAST TO LAKE ERIE BY MIDDAY THEN CONTINUE TO THE CAROLINA COAST
TONIGHT AND MERGE WITH DEVELOPING LOW PRESSURE. VERY STRONG HIGH
PRESSURE STRETCHED ACROSS THE NORTHERN PLAINS INTO CENTRAL CANADA IS
THE KEY TO THE RAPIDLY INCREASING WINDS THAT ARE NOW REACHING THE
NORTHERN PORTION OF THE LAKE. THE PRESSURE GRADIENT WILL QUICKLY
INCREASE ACROSS THE LAKE INTO MID MORNING AS A COLD FRONT SWEEPS
ACROSS ALLOWING MUCH COLDER AIR TO SPREAD DOWN THE LAKE. NORTH WINDS
WILL LIKELY INCREASE TO STORM FORCE AROUND 50 KT FOR MOST OF THE
LAKE WITH THE FAR NORTHERN SECTION HOLDING AT GALES...THOUGH A FEW
50 KT GUSTS COULD OCCUR THIS MORNING. MAY SEE SOME 55 KT GUSTS AT
TIMES ACROSS THE SOUTH HALF OF THE LAKE...ESPECIALLY LATE THIS
MORNING INTO MIDDAY. THIS RAPID INCREASE IN WINDS AND STRONG
MIXING OVER THE LAKE WILL ALLOW FOR A RAPID BUILDING OF WAVES
THROUGH THE MORNING TO AROUND 20 FEET BY EARLY/MID AFTERNOON
ACROSS THE CENTRAL AND SOUTHERN PART OF THE LAKE. WILL CONTINUE
WITH 18-23 FT PREVAILING WAVES IN THE FORECAST FOR THESE AREAS.
WINDS WILL BEGIN TO EASE THIS EVENING AND TREND A BIT
NORTHEASTERLY. SHOULD SEE WINDS FALL BELOW GALE FORCE OVERNIGHT
BUT WINDS WILL BE SLOW TO DIMINISH SIGNIFICANTLY THROUGH MIDDAY
SATURDAY SO WAVES WILL LIKELY BE SLOW TO FALL AS WELL. WILL LEAVE
EXISTING GALE AND STORM WARNINGS AS-IS.

THE HIGH WILL PASS OVER THE LAKE SATURDAY EVENING THROUGH SUNDAY
KEEPING WINDS LIGHT BUT SOUTH TO SOUTHWEST WINDS WILL INCREASE
THROUGH THE DAY SUNDAY AND MAY PUSH 30 KT LATE SUNDAY
AFTERNOON/EVENING AS LOW PRESSURE TRACKS NORTHEAST ACROSS THE
NORTHERN PLAINS. SOUTHWEST WINDS WILL REMAIN STRONG THROUGH MONDAY
NIGHT THEN LET UP NORTH AS LOW PRESSURE TRACKS FROM THE SOUTHERN
PLAINS ACROSS NORTHERN LAKE MICHIGAN...WHILE THE SOUTH SEES BREEZY
CONDITIONS CONTINUE. WINDS TURN WESTERLY LATER TUESDAY AND
DIMINISH AS HIGH PRESSURE RIDGING EXTENDS ACROSS THE AREA.

MDB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HIGH WIND WARNING...ILZ014 UNTIL 6 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014 UNTIL 4 AM SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022-ILZ023-
     ILZ033 UNTIL 7 PM FRIDAY.

IN...HIGH WIND WARNING...INZ001-INZ002 UNTIL 6 PM FRIDAY.

     LAKE EFFECT SNOW ADVISORY...INZ001-INZ002-INZ010-INZ011 UNTIL 10
     PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...INZ001-INZ002 UNTIL 4 AM SATURDAY.

     WIND ADVISORY...INZ010-INZ011-INZ019 UNTIL 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 PM FRIDAY TO
     4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563 UNTIL 10 PM FRIDAY.

     GALE WARNING...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 4 AM SATURDAY.

&&

$$

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000
FXUS63 KILX 311752
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1252 PM CDT Fri Oct 31 2014

.UPDATE...
ISSUED AT 1042 AM CDT FRI OCT 31 2014
Cold front has moved through the area in the overnight hours, with
colder air and blustery winds. North/northwesterly winds up to and
in excess of 25 mph expected this afternoon, gusting to 30-35 mph.
Just shy of advisory criteria for the forecast area, but enough to
drop the wind chills into the 20s and 30s. Forecast on track
across the board. Early morning echos moving along the I-74
corridor btwn BMI and CMI have moved out to the east. Another
round of light precip (possibly a ra/sn mix) along the northern
half of the IL/IN border this afternoon as winds become
increasingly northerly and a fetch off of Lake Michigan enhances
some lake effect...and remnants may reach into the extreme east. Some
minor tweaks here and there in the forecast, and pulling the
morning wording...but overall, forecast looks good.

&&

.SHORT TERM...(Today)
ISSUED AT 330 AM CDT FRI OCT 31 2014

The passage of a strong cold front and upper level shortwave will
highlight the short term forecast. At 08z/3am the front had already
reached near the Illinois River Valley, with the upper wave centered
behind the front across Wisconsin. Very gusty northwest winds were
lagging behind the front by a couple of hours, so winds in our
counties will begin to increase by around sunrise, especially NW of
Lincoln. Wind gusts this afternoon will climb into the 30-40 mph
range, especially east of Peoria to Springfield. Spotty rain showers
or sprinkles were developing just ahead of the front, generally
along and east of the I-55 corridor at 3 am.

Spotty showers will continue to advance eastward with the front
today, then linger this afternoon as the upper level shortwave
affects eastern Illinois. As colder air arrives on brisk northwest
winds today, some of the light rain showers could change over to
snow showers for areas east of Champaign and north of Paris.

Highs today will likely occur this morning, as the colder air and
cloud cover prevent temperatures from rising much this afternoon.
Temps will likely become steady or slowly fall by midday in most
areas.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 330 AM CDT FRI OCT 31 2014

A potent Canadian shortwave will dive sse from Lake Superior and WI
across IN/KY tonight. North-northwest winds 20-30 mph with gusts
30-40 mph will diminish to 10-15 mph overnight with gusts up to 20
mph. This will advect in subfreezing temperatures of 25-30F and
bring a killing freeze to much of IL overnight until mid morning
Saturday. Will continue the freezing warning overnight until 9 am
Sat for central and southeast IL. Moisture flow off Lake MI could
bring a few snow showers near the IN border especially over
Vermilion county this evening. A taste of early winter weather for
Halloween Trick or Treaters this evening with wind chills slipping
into the low to mid 20s. Chilly highs in the mid 40s Saturday
despite a fair amount of sunshine, due to north winds 8-15 mph and
gusts 15 to 20 mph over eastern IL.

Strong Canadian high pressure of 1039 mb over ND will settle over IL
Saturday night as it slowly weakens with fair skies and light winds.
This will bring another hard freeze overnight Saturday night and
early Sunday morning with lows in the middle to upper 20s, and
coldest east of I-57. Mostly sunny skies Sunday but still chilly
highs in the upper 40s to around 50F.

More unsettled weather pattern takes shape Monday-Wednesday as IL
gets in a southwesterly upper level flow with upper level ridge
shifting east of IL and strong upper level trof digging into the
southern Rockies. A frontal boundary will set up from the southern
Plains ne into the Ohio river valley Monday night through Wed and
bring increasing chances of showers. Cold front to move se across
central IL Tue when best chances of showers and isolated
thunderstorms will be. Have 20-30% chance of showers by Monday
afternoon west of I-55 as clouds increasing from the west during the
day. Then likely chances of showers develop during Monday night into
Tue and highest pops shift into southeast IL during Tue night and
Wed. Milder highs in the upper 50s and lower 60s Monday and 55-60F
Tue and Wed. Isolated thunderstorms may also occur Monday night and
Tue south of I-72. Slight chance of showers in southeast IL Wed
evening, otherwise drier weather is expected Wed night thru Friday
as dry west northwesterly flow trails the system with seasonable
highs still in the mid to upper 50s and near 60F in southeast IL.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1243 PM CDT FRI OCT 31 2014
VFR throughout. Main issue is the wind today. North/northwest,
23 to 28 kts sustained, and gusting in excess of 35 kts. Ceilings
confined to mainly the eastern half of the state, DEC, CMI and BMI
at this point between 3500-4000 ft. Lake effect showers streaming
into far eastern portions of the state...but just east of CMI so
far. Winds expected to ease somewhat going into the overnight...as
the atmosphere decouples and lose the gusts from mid levels.
Although the winds will decrease in the overnight, they will still
be in the 15-20kt range for much of the evening...and 10-15kt
after 06z. Current cloud cover has a strong diurnal component to
what is left from the frontal passage, and expect the clouds to
scatter out just before sunset in ILX terminals, save CMI where
the lake effect showers likely to keep clouds over to the east a
bit longer into the overnight.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING from Midnight tonight to 9 AM CDT Saturday FOR
ILZ027>031-036>038-040>057-061>063-066>068-071>073.

&&

$$

UPDATE...HJS
SHORT TERM...Shimon
LONG TERM...07
AVIATION...HJS







000
FXUS63 KLOT 311628
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1128 AM CDT FRI OCT 31 2014

.MESOSCALE DISCUSSION...

WE ARE CURRENTLY WATCHING THE PROGRESS OF A SECONDARY INVERTED
SURFACE TROUGH...WHICH IS CURRENTLY RACING SOUTHWARD DOWN CENTRAL
LAKE MICHIGAN. OBSERVATIONS OVER AND NEAR THE LAKE INDICATE THE
PRESENCE OF GOOD CONVERGENCE ALONG THIS BOUNDARY. THE FIRST
MORNING VISIBLE SATELLITE IMAGES ALSO INDICATE CONVECTIVE
STRUCTURES DEVELOPING WITHIN THE BAND OF RAIN/SNOW SHOWERS
CURRENTLY SHIFTING SOUTHWARD JUST EAST OF MKE. OVERALL IT APPEARS
THIS AREA OF SNOWFALL WILL PIVOT SOUTHWARD ACROSS NORTHWESTERN
INDIANA WITHIN THE NEXT 2 HOURS (BY 1630Z). HOWEVER...I AM ALSO
CONCERNED THAT SOME OF THESE HEAVIER CONVECTIVE SNOW SHOWERS MAY
IMPACT PORTIONS OF NORTHEASTERN ILLINOIS...INCLUDING DOWNTOWN
CHICAGO THROUGH LATE MORNING. IN FACT...SOME OF THE LATEST RADAR
IMAGERY IS ALREADY INDICATING SOME BANDS OF PRECIP MOVING INTO
NORTHERN COOK COUNTY. IT APPEARS THE WINDS WILL BECOME MORE
NORTHERLY IN THE WAKE OF THIS SURFACE TROUGH...AND WIND SPEEDS
COULD ALSO INCREASE A BIT HIGHER THAN CURRENT WIND SPEEDS. WE WILL
CONTINUE TO WATCH OBSERVATION TRENDS...AND HANDLE THIS SNOWFALL
ACROSS THE CHICAGO AREA WITH GRAPHICAL NOWCASTS AT THIS TIME. IT
DOES APPEAR THIS INITIAL BURST OF SNOW WILL BE SOMEWHAT SHORT
LIVED ACROSS THE CHICAGO METRO AREA. WHILE SOME MINOR
ACCUMULATIONS ARE CERTAINLY POSSIBLE WITH THIS ACTIVITY...WE HAVE
NO IMMEDIATE PLANS TO EXPAND THE CURRENT WINTER WEATHER HEADLINES.

FOLLOWING THIS INITIAL BOUNDARY AND BURST OF SNOW...HI RES GUIDANCE
CONTINUES TO INDICATE THAT BANDS OF LAKE EFFECT RAIN/SNOW SHOWERS
WILL CONTINUE TO DEVELOP AND IMPACT MUCH OF THE AREAS CURRENTLY
UNDER THE WINTER HEADLINE ACROSS NORTHWESTERN INDIANA. HOWEVER...WE
WILL NEED TO WATCH FOR THE POTENTIAL OF THE LAKE EFFECT BANDS THIS
AFTERNOON TRYING TO WORK MORE WEST INTO EASTERN ILLINOIS. SOME
GUIDANCE DOES SUGGEST THAT THE LAKE EFFECT BANDS WILL EFFECT AREAS
NEAR...OR EVEN ALONG THE ILLINOIS...INDIANA STATE LINE....AND
POSSIBLY PARTS OF CHICAGO AS WELL. HOWEVER...GIVEN THE MODEL
DIFFERENCES...AND UNCERTAINTY STILL INHERENT IN WHERE ANY LAKE EFFECT
BAND...OR BANDS WILL SET UP...I WOULD LIKE TO WATCH THE EVOLUTION OF
CONDITIONS OVER THE LAKE BEFORE PUSHING SNOWFALL AMOUNTS...AND WINTER
HEADLINES FARTHER WEST.

NO BIG CHANGES ARE PLANNED FOR THE UPDATE. HOWEVER...I WILL LIKELY
ADD A MENTION OF LIGHT SNOW/FLURRIES FOR AREAS A BIT FARTHER INLAND
ACROSS NORTHEASTERN ILLINOIS BASED ON REPORTS OF LIGHT SNOW...AND
RADAR TRENDS.

KJB

&&

PREVIOUS DISCUSSION...

.SHORT TERM...
326 AM CDT

THROUGH SATURDAY...

ACTIVE WEATHER ON TAP THE NEXT 24 HOURS AS COMPACT AND DEEP UPPER
LOW DIVES SOUTH ACROSS THE REGION DRAGGING UNSEASONABLY COLD
AIR...BOTH AT THE SURFACE AND ALOFT...INTO THE REGION TODAY INTO
TONIGHT. EARLY THIS MORNING SURFACE ANALYSIS SHOWS A RATHER DIFFUSE
COLD FRONT MOVING ACROSS THE REGION WITH STRONG COLD ADVECTION
RESULTING IN A HEALTHY TEMP DROP PRIOR TO SUNRISE OVER NORTHERN CWA
AND SHORTLY AFTERWARD SOUTHEAST. STRONG NNW WINDS WILL ALSO ARRIVE
WITH THE COLD AIR AND CONTINUE INTO THIS EVENING RESULTING IN
TEMPERATURES LARGELY REMAINING FAIRLY STEADY THROUGH THE AFTERNOON.

COMPACT VORT AND REALLY THE HEART OF THE UPPER LOW SHOWS UP NICELY
OVER NORTHERN WISCONSIN EARLY THIS MORNING AND IS DIVING SSE TOWARD
THE AREA. THE COMBINATION OF ASCENT WITH THIS FEATURE AND STEEP
LAPSE RATES ARE RESULTING IN SCATTERED BUT FAIRLY VIGOROUS SNOW
SHOWERS OVER NORTHERN AND CENTRAL WISCONSIN AND WOULD FULLY
ANTICIPATE THESE TO MAINTAIN THEMSELVES AND MOVE ACROSS MAINLY THE
EASTERN CWA THIS MORNING. TEMPS WILL PROBABLY BE TOO WARM FOR MUCH
IF ANY ACCUMULATION...BUT SOME OF THE SNOW SHOWERS COULD BE BRIEFLY
VIGOROUS AND KNOCK VSBY DOWN TO BELOW 1SM. AS THE VORT CONTINUE
SOUTHEAST LOOK FOR THE NON-LAKE DRIVEN PRECIP TO END BY MID MORNING
NORTHERN CWA AND LATE MORNING SOUTHEAST CWA.

THE VORT WILL HERALD THE ARRIVAL OF THE COLDEST AIR ALOFT AND
RESULTANT STRONGEST INSTABILITY OVER THE LAKE AS H5 TEMPS DROP TO
-33C AND H7 TEMPS BELOW -15C. THERMODYNAMIC PROFILES OVER THE LAKE
BEHIND THIS VORT BECOME EXPLOSIVELY UNSTABLE THIS MORNING REMAIN SO
THROUGH THE DAY. LAKE EFFECT SHOULD GET GOING IN ERNEST BEHIND THIS
VORT AND CONTINUE TO SOME DEGREE INTO SATURDAY MORNING. FORECAST
LAKE INDUCED EQUILIBRIUM LEVELS TODAY APPROACH 20K FT...NEAR THE
-30C LEVEL...WHICH IS MORE THAN COLD ENOUGH TO SUPPORT LIGHTNING
GIVEN THE HIGH LIKELIHOOD OF MIXED PHASE HYDROMETEORS (SUPERCOOLED
DROPLETS AND ICE) IN THE CLOUDS WITHIN STRONG UPDRAFTS. NEAR SURFACE
TEMPS OVER THE LAKE AND WITHIN A FEW MILES OF THE LAKE SHORE MAY BE
WARM ENOUGH TO SUPPORT P-TYPE FLUCTUATING BETWEEN RAIN...RAIN/SNOW
MIX...AND ALL SNOW. LAKE EFFECT PRECIP FARTHER INLAND STANDS A MUCH
BETTER CHANCE OF REMAINING ALL OR MOSTLY SNOW.

ONE OF THE BIGGER UNCERTAINTIES FOR TODAY IS HOW ORGANIZED THE LAKE
EFFECT WILL BECOME AND WHETHER IT WILL BE MULTIPLE BANDS OR A SINGLE
INTENSE BAND. GIVEN THE VERY STRONG BOUNDARY LAYER WINDS AND LESS
THAN IDEAL TIME OF DAY AM CONCERNED THAT THE LAKE EFFECT PRECIP
COULD BE SOMEWHAT UNORGANIZED/SCATTERED IN NATURE WITH MULTIPLE
BANDS DURING THE DAY WHICH WILL BE THE TIME OF STRONG TO EXTREME
INSTABILITY. IF A MORE ORGANIZED DOMINANT SINGLE BAND DOES
FORM...THE STRONG FLOW AND INSTABILITY WELL INLAND WOULD SUPPORT
INTENSE PRECIP RATES MAKING IT WELL INLAND THIS AFTERNOON WHERE
P-TYPE WOULD LIKELY BE MOSTLY SNOW...POSSIBLY MODERATE TO HEAVY
SNOW. IF SNOW FALLS HEAVY ENOUGH THEN THE WARM GROUND TEMPS WOULD
BECOME MORE OF A MOOT POINT WITH RAPID ACCUMULATIONS OF HEAVY/WET
SNOW...ESPECIALLY ON GRASSY SURFACES WHERE ISOLATED LOCATIONS COULD
SEE A QUICK SEVERAL INCHES OF SNOW. THE MOST LIKELY SCENARIO WOULD
APPEAR TO BE SOMEWHAT LESS ORGANIZED BANDS OF SNOW SHOWERS RESULTING
IN ONLY MINOR ACCUMS ON GRASSY SURFACES IN SPOTS TODAY. THE WIND
WILL BE WHIPPING THE SNOW AROUND REGARDLESS SO UNDERNEATH ANY LAKE
EFFECT SNOW CONDITIONS WILL BE PRETTY MISERABLE EVEN THOUGH IT IS
UNLIKELY TO ACCUMULATE ON ROADS/SIDEWALKS TODAY. LAKE AND PORTER
COUNTY LOOK TO BE GROUND ZERO FOR THE LAKE EFFECT TODAY WITH THE
PRECIP LIKELY MAKING IT WELL INLAND TO JASPER AND NEWTON COUNTIES.
SOME HIGH RES GUIDANCE DOES CLIP SE COOK AND EASTERN WILL WITH LAKE
EFFECT PRECIP TODAY WHICH ISNT OUT OF THE QUESTION AND HAVE
MAINTAINED LOW POPS THERE.

THIS EVENING THE LOW LEVEL FLOW WILL GRADUALLY VEER AND SEND THE
LAKE EFFECT MORE INTO EASTERN COOK/EASTERN WILL/WESTERN LAKE IN (AND
EVEN POINTS SOUTH. BY THIS EVENING THE BOUNDARY LAYER FLOW WILL BE
WEAKENING AND THE TEMPS OUTSIDE OF THE LAKE INFLUENCED AREAS
DROPPING WHICH WOULD BOTH TEND TO FAVOR A TRANSITION TO A MORE
ORGANIZED DOMINANT SINGLE LAKE EFFECT BAND. MY BEST GUESS IS THAT
THE TIME WINDOW FOR THE HIGHEST PROBABILITY OF A DOMINANT LAKE
EFFECT BAND WITH POTENTIAL FOR HEAVY SNOW IS BETWEEN 23Z AND ABOUT
04Z. DURING THIS TIME PERIOD THE INSTABILITY (WHILE LESS THAN
EARLIER IN THE DAY) WILL STILL BE STRONG WITH INVERSION HEIGHTS
AROUND 10K FT AND LAKE-850 DELTA T VALUES >20C. DOES APPEARS A
PERIOD OF HEAVY SNOW COULD OCCUR IN EASTERN/SOUTHEASTERN COOK AND
EASTERN WILL COUNTIES EARLY THIS EVENING...BUT GIVEN THE LOW
CONFIDENCE OPTED NOT TO EXPAND THE WINTER WX HEADLINES AT THIS TIME
AND INSTEAD WILL ALLOW DAY SHIFT TO MONITOR MESOSCALE TRENDS. BY
LATER THIS EVENING INTO THE OVERNIGHT HOURS THE LAKE EFFECT
PARAMETERS WILL CONTINUE TO BECOME LESS FAVORABLE AND THE INTENSITY
OF THE LAKE EFFECT PRECIP SHOULD BEGIN TO WIND DOWN LATE TONIGHT AND
EVENTUALLY END SATURDAY. HAVE EXTENDED THE HIGHER POPS LATER IN TIME
AS LAKE EFFECT RARELY WINDS DOWN AS QUICKLY AS MODEL PROGGED
PARAMETERS SUGGEST IT WILL. WORTH NOTING THAT BY LATE EVENING AND
THROUGH SAT MORNING THE CONVECTIVE CLOUD TOP TEMPS DROP BELOW -12C
MEANING THE LIKELIHOOD OF CLOUDS CONTAINING ICE NUCLEI FOR SNOW WILL
BE LOW...SO DESPITE LOWER TEMPS IN THE BOUNDARY LAYER HAVE
TRANSITIONED P-TYPE BACK TO RAIN OR SNOW LATE TONIGHT AND SAT
MORNING.

FINALLY...HIGH WINDS WILL BE THE OTHER CONCERN TODAY. PLAN TO
MAINTAIN WIND ADVISORY AS IS THOUGH CONFIDENCE IN INLAND LOCATIONS
REACHING ADVISORY CRITERIA IS NOT THAT HIGH...BUT WITH GUSTS TO AT
LEAST 40 MPH A GOOD BET NOTHING WOULD BE GAINED FROM MAKING ANY
CHANGES TO THE HEADLINES. THE STORM WARNING FOR THE LAKE LOOKS
LIKELY TO VERIFY WITH 40 MPH SUSTAINED AND POSSIBLY GUSTS TO 58 MPH
LIKELY ALONG THE LAKE FRONT TODAY AND REALLY NOT COMFORTABLE NOT
HAVING A WARNING WITH THE POTENTIAL FOR DAMAGING WINDS ALONG THE
LAKE...SO AM GOING TO UPGRADE TO A HIGH WIND WARNING FOR LAKE SHORE
AREAS.

HEADLINES ARE AN ABSOLUTE MESS AND HEADACHE. WINTER WX ADVISORY
COVERS WIND AND SNOW...BUT IN ORDER TO GO WITH WARNING FOR WIND
ALONG THE LAKE FRONT IN INDIANA WOULD NEED TO UPGRADE TO A WINTER
STORM WARNING WHICH REALLY DOESNT SEEM TO BE THE BEST PRODUCT. AFTER
MUCH HEMMING AND HAWING AND INTERNAL COORDINATION HAVE OPTED TO
CHANGE THE WINTER WX ADV TO A LAKE EFFECT SNOW ADVISORY AND ISSUE A
WIND ADVISORY FOR JASPER AND NEWTON AND A HIGH WIND WARNING FOR LAKE
SHORE AREAS OF COOK...PORTER...AND LAKE IN. MAY NEED TO REPLACE THE
HIGH WIND WARNING WITH A WIND ADVISORY BY EARLY EVENING FOR

IZZI

&&

.AVIATION...

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

* PERIODS OF FLURRIES THIS AFTERNOON WITH THE POTENTIAL FOR SOME
  TEMPORARY SNOW SHOWERS NAMELY AT MDW.

* VERY GUSTY NORTHWEST WINDS PROBABLE TO SHIFT DUE NORTH EARLY
  THIS AFTERNOON. SPORADIC GUSTS IN EXCESS OF 40 KT.

* CIGS POTENTIALLY DROPPING TO 2000-3000 FT AGAIN THIS AFTERNOON.

* LAKE EFFECT SNOW SHOWERS COULD FURTHER AFFECT MDW THIS EVE.

MTF/MDB

//DISCUSSION...UPDATED 14Z...

NORTH-NORTHWEST WINDS HAVE BEEN VERY STEADY AT 340-350 AT ORD AND
MDW. A SECONDARY COLD FRONT/TROUGH IS MOVING SOUTHWARD DOWN LAKE
MICHIGAN AND WISCONSIN AND THIS WILL TURN WINDS MORE DUE NORTH.
THIS IS SLIGHTLY LATER FOR DUE NORTH THAN PREVIOUS TAF. WIND SPEED
THINKING REMAINS THE SAME.

CONVECTIVE CLOUD TOPS ARE BEGINNING TO SHOW UP ACROSS THE CENTRAL
AND SOUTHERN PART OF THE LAKE SO IT IS POSSIBLE WE BEGIN TO SEE
SOME LIGHTNING AS WELL.

PREV DISCUSSION...UPDATED 12Z...

NORTHWEST WINDS HAVE BEEN STEADILY INCREASING EARLY THIS MORNING
AS STRONG HIGH PRESSURE APPROACHES FROM THE NORTHWEST. ONE UPPER
WAVE AND ASSOCIATED -SHRA IS DEPARTING WHILE ANOTHER IS APPROACHING
FROM THE NORTH. A PUSH OF COLDER AIR WITH THE NEXT WAVE IS
RESULTING IN A BAND OF SNOW SHOWERS WHICH HAS BEEN REDUCING VSBY
TO AROUND A MILE AT TIMES...AT LEAST BRIEFLY. EXPECT A 1-2 HR
WINDOW OF -SHSN AT THE TERMINALS OVER THE NEXT 2-3 HRS. VARIABLE
MVFR-VFR CIGS WILL CONTINUE THROUGH MUCH OF THE MORNING BEFORE
STEADIER VFR IS EXPECTED ACROSS THE ILLINOIS TERMINALS WITH
SCATTERING OF CLOUDS WEST.

WINDS WILL TURN TO THE NORTH WITH THE PASSAGE OF THE UPPER WAVE
THIS MORNING AND EXPECT TO SEE A SURGE IN GUSTS AT THAT TIME. 35
TO 40 KT GUSTS ARE EXPECTED BUT AM NOT HIGHLY CONFIDENT IN HOW
FREQUENTLY 40 KT MAY BE REACHED. IT APPEARS THAT MID MORNING MAY
BE ONE POTENTIALLY PRIME PERIOD BEHIND THE UPPER WAVE/PRECIP WITH
THE NEXT POTENTIALLY FAVORED TIME BEING MID AFTERNOON IF SKIES CAN
SCATTER. IT MAY BE THAT AN OCCASIONAL 40 KT GUST OCCURS AT ANY
POINT THROUGH THE DAY. WINDS WILL EASE THIS EVENING.

LAKE EFFECT PRECIPITATION IS EXPECTED TO DEVELOP MID TO LATE
MORNING AND FOCUS ACROSS NORTHWEST INDIANA WITH GYY POSSIBLY BEING
ON THE WESTERN FRINGE INITIALLY BUT LIKELY GETTING INTO THE PRIME
BANDING INTO THE AFTERNOON. GIVEN THEIR PROXIMITY TO THE FAIRLY
WARM LAKE A RAIN SNOW MIX IS FAVORED TURNING TO ALL SNOW IF VERY
INTENSE BANDING CAN OCCUR. THUNDER IS ALSO POSSIBLE AND WOULD
ENHANCE THE ALL SNOW POTENTIAL. AS A RESULT IFR VSBY WILL LIKELY
OCCUR AT TIMES BUT THERE ARE FACTORS THAT MAY LIMIT THE
ORGANIZATION OF THE PRECIP. WINDS WILL LIKELY GUST 40-45 KT WITH
50 NOT OUT OF THE QUESTION TOWARD MIDDAY. LAKE EFFECT PRECIP WILL
LIKELY TURN TO ALL SNOW THIS EVENING AND SHIFT WESTWARD TOWARD THE
IL/IN STATE LINE AND POSSIBLY BEGIN TO IMPACT MDW WITH LIGHT
ACCUMULATIONS POSSIBLE...MAINLY ON THE GRASS. SEVERAL HOURS OF
SNOW MAY OCCUR AT OR NEAR MDW. ADJUSTMENTS TO THE FORECAST DETAILS
THIS EVENING AT MDW/GYY AND EVEN ORD ARE LIKELY.

MDB

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

* LOW ON IF IFR SNOW SHOWERS MAY IMPACT MDW THIS AFTERNOON.
  MEDIUM THAT THEY WILL STAY EAST OF ORD.

* HIGH IN NORTHWEST WINDS TURNING DUE NORTH BUT LOW IN EXACT
  TIMING. HIGH IN WIND SPEEDS AND THAT GUSTS WILL EXCEED 35 KT
  MUCH OF THIS AFTERNOON.

* HIGH THAT CIGS WILL REMAIN ABOVE 2000 FT.

* MEDIUM IN LAKE EFFECT SNOW SHOWER POTENTIAL TONIGHT AT MDW...LOW
  AT ORD.

MTF/MDB

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

* SATURDAY NIGHT...DRY VFR. LIGHT/VARIABLE WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS 10-15 KT.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.
* TUESDAY...SHRA/MVFR LIKELY. SOUTHWEST WINDS.
* WEDNESDAY...DRY/VFR. SOUTHWEST WINDS.
* THURSDAY...DRY/VFR. WEST WINDS.

MDB

&&

.MARINE...
256 AM CDT

A MAJOR WIND EVENT CONTINUES TO TAKE SHAPE FOR LAKE MICHIGAN EARLY
THIS MORNING. FAIRLY BROAD LOW PRESSURE OVER LAKE HURON WILL TRACK
SOUTHEAST TO LAKE ERIE BY MIDDAY THEN CONTINUE TO THE CAROLINA COAST
TONIGHT AND MERGE WITH DEVELOPING LOW PRESSURE. VERY STRONG HIGH
PRESSURE STRETCHED ACROSS THE NORTHERN PLAINS INTO CENTRAL CANADA IS
THE KEY TO THE RAPIDLY INCREASING WINDS THAT ARE NOW REACHING THE
NORTHERN PORTION OF THE LAKE. THE PRESSURE GRADIENT WILL QUICKLY
INCREASE ACROSS THE LAKE INTO MID MORNING AS A COLD FRONT SWEEPS
ACROSS ALLOWING MUCH COLDER AIR TO SPREAD DOWN THE LAKE. NORTH WINDS
WILL LIKELY INCREASE TO STORM FORCE AROUND 50 KT FOR MOST OF THE
LAKE WITH THE FAR NORTHERN SECTION HOLDING AT GALES...THOUGH A FEW
50 KT GUSTS COULD OCCUR THIS MORNING. MAY SEE SOME 55 KT GUSTS AT
TIMES ACROSS THE SOUTH HALF OF THE LAKE...ESPECIALLY LATE THIS
MORNING INTO MIDDAY. THIS RAPID INCREASE IN WINDS AND STRONG
MIXING OVER THE LAKE WILL ALLOW FOR A RAPID BUILDING OF WAVES
THROUGH THE MORNING TO AROUND 20 FEET BY EARLY/MID AFTERNOON
ACROSS THE CENTRAL AND SOUTHERN PART OF THE LAKE. WILL CONTINUE
WITH 18-23 FT PREVAILING WAVES IN THE FORECAST FOR THESE AREAS.
WINDS WILL BEGIN TO EASE THIS EVENING AND TREND A BIT
NORTHEASTERLY. SHOULD SEE WINDS FALL BELOW GALE FORCE OVERNIGHT
BUT WINDS WILL BE SLOW TO DIMINISH SIGNIFICANTLY THROUGH MIDDAY
SATURDAY SO WAVES WILL LIKELY BE SLOW TO FALL AS WELL. WILL LEAVE
EXISTING GALE AND STORM WARNINGS AS-IS.

THE HIGH WILL PASS OVER THE LAKE SATURDAY EVENING THROUGH SUNDAY
KEEPING WINDS LIGHT BUT SOUTH TO SOUTHWEST WINDS WILL INCREASE
THROUGH THE DAY SUNDAY AND MAY PUSH 30 KT LATE SUNDAY
AFTERNOON/EVENING AS LOW PRESSURE TRACKS NORTHEAST ACROSS THE
NORTHERN PLAINS. SOUTHWEST WINDS WILL REMAIN STRONG THROUGH MONDAY
NIGHT THEN LET UP NORTH AS LOW PRESSURE TRACKS FROM THE SOUTHERN
PLAINS ACROSS NORTHERN LAKE MICHIGAN...WHILE THE SOUTH SEES BREEZY
CONDITIONS CONTINUE. WINDS TURN WESTERLY LATER TUESDAY AND
DIMINISH AS HIGH PRESSURE RIDGING EXTENDS ACROSS THE AREA.

MDB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HIGH WIND WARNING...ILZ014 UNTIL 6 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014 UNTIL 4 AM SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022-ILZ023-
     ILZ033 UNTIL 7 PM FRIDAY.

IN...HIGH WIND WARNING...INZ001-INZ002 UNTIL 6 PM FRIDAY.

     LAKE EFFECT SNOW ADVISORY...INZ001-INZ002-INZ010-INZ011 UNTIL 10
     PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...INZ001-INZ002 UNTIL 4 AM SATURDAY.

     WIND ADVISORY...INZ010-INZ011-INZ019 UNTIL 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 PM FRIDAY TO
     4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563 UNTIL 10 PM FRIDAY.

     GALE WARNING...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 4 AM SATURDAY.

&&

$$

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

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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000
FXUS63 KILX 311549
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1049 AM CDT Fri Oct 31 2014

.UPDATE...
ISSUED AT 1042 AM CDT FRI OCT 31 2014
Cold front has moved through the area in the overnight hours, with
colder air and blustery winds. North/northwesterly winds up to and
in excess of 25 mph expected this afternoon, gusting to 30-35 mph.
Just shy of advisory criteria for the forecast area, but enough to
drop the wind chills into the 20s and 30s. Forecast on track
across the board. Early morning echos moving along the I-74
corridor btwn BMI and CMI have moved out to the east. Another
round of light precip (possibly a ra/sn mix) along the northern
half of the IL/IN border this afternoon as winds become
increasingly northerly and a fetch off of Lake Michigan enhances
some lake effect...and remnants may reach into the extreme east. Some
minor tweaks here and there in the forecast, and pulling the
morning wording...but overall, forecast looks good.

&&

.SHORT TERM...(Today)
ISSUED AT 330 AM CDT FRI OCT 31 2014

The passage of a strong cold front and upper level shortwave will
highlight the short term forecast. At 08z/3am the front had already
reached near the Illinois River Valley, with the upper wave centered
behind the front across Wisconsin. Very gusty northwest winds were
lagging behind the front by a couple of hours, so winds in our
counties will begin to increase by around sunrise, especially NW of
Lincoln. Wind gusts this afternoon will climb into the 30-40 mph
range, especially east of Peoria to Springfield. Spotty rain showers
or sprinkles were developing just ahead of the front, generally
along and east of the I-55 corridor at 3 am.

Spotty showers will continue to advance eastward with the front
today, then linger this afternoon as the upper level shortwave
affects eastern Illinois. As colder air arrives on brisk northwest
winds today, some of the light rain showers could change over to
snow showers for areas east of Champaign and north of Paris.

Highs today will likely occur this morning, as the colder air and
cloud cover prevent temperatures from rising much this afternoon.
Temps will likely become steady or slowly fall by midday in most
areas.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 330 AM CDT FRI OCT 31 2014

A potent Canadian shortwave will dive sse from Lake Superior and WI
across IN/KY tonight. North-northwest winds 20-30 mph with gusts
30-40 mph will diminish to 10-15 mph overnight with gusts up to 20
mph. This will advect in subfreezing temperatures of 25-30F and
bring a killing freeze to much of IL overnight until mid morning
Saturday. Will continue the freezing warning overnight until 9 am
Sat for central and southeast IL. Moisture flow off Lake MI could
bring a few snow showers near the IN border especially over
Vermilion county this evening. A taste of early winter weather for
Halloween Trick or Treaters this evening with wind chills slipping
into the low to mid 20s. Chilly highs in the mid 40s Saturday
despite a fair amount of sunshine, due to north winds 8-15 mph and
gusts 15 to 20 mph over eastern IL.

Strong Canadian high pressure of 1039 mb over ND will settle over IL
Saturday night as it slowly weakens with fair skies and light winds.
This will bring another hard freeze overnight Saturday night and
early Sunday morning with lows in the middle to upper 20s, and
coldest east of I-57. Mostly sunny skies Sunday but still chilly
highs in the upper 40s to around 50F.

More unsettled weather pattern takes shape Monday-Wednesday as IL
gets in a southwesterly upper level flow with upper level ridge
shifting east of IL and strong upper level trof digging into the
southern Rockies. A frontal boundary will set up from the southern
Plains ne into the Ohio river valley Monday night through Wed and
bring increasing chances of showers. Cold front to move se across
central IL Tue when best chances of showers and isolated
thunderstorms will be. Have 20-30% chance of showers by Monday
afternoon west of I-55 as clouds increasing from the west during the
day. Then likely chances of showers develop during Monday night into
Tue and highest pops shift into southeast IL during Tue night and
Wed. Milder highs in the upper 50s and lower 60s Monday and 55-60F
Tue and Wed. Isolated thunderstorms may also occur Monday night and
Tue south of I-72. Slight chance of showers in southeast IL Wed
evening, otherwise drier weather is expected Wed night thru Friday
as dry west northwesterly flow trails the system with seasonable
highs still in the mid to upper 50s and near 60F in southeast IL.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
ISSUED AT 659 AM CDT FRI OCT 31 2014

A brief period of MVFR clouds around 2k FT will affect DEC and CMI
through 13-14z before mixing lifts the cloud deck into the VFR
range. Then VFR conditions will prevail the remainder of the TAF
forecast. NW winds will increase early this morning with sustained
20-25kt and gusts to near 40kt at times by 16-17z.

The leading edge of a strong shortwave aloft could trigger a few
rain or snow showers between 14z and 18z for the northern taf
sights of PIA/BMI/CMI. Any snow would melt as it falls. Otherwise,
precipitation should be minimal at all TAF sites over the next 24
hours. Latest HRRR forecast indicates the stratocumulus should
begin to decrease in coverage and affect mainly areas east of I55
by afternoon as subsidence develops in the wake of the upper level
shortwave. Skies should become clear even over eastern areas
after 00z tonight. Surface winds will gradually diminish,
especially the gusts, toward evening with sustained winds of
12-15 kts after 02z.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING from Midnight tonight to 9 AM CDT Saturday FOR
ILZ027>031-036>038-040>057-061>063-066>068-071>073.

&&

$$

UPDATE...HJS
SHORT TERM...Shimon
LONG TERM...07
AVIATION...Shimon







000
FXUS63 KLOT 311505
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1005 AM CDT FRI OCT 31 2014

.MESOSCALE DISCUSSION...
1001 AM CDT

WE ARE CURRENTLY WATCHING THE PROGRESS OF A SECONDARY INVERTED
SURFACE TROUGH...WHICH IS CURRENTLY RACING SOUTHWARD DOWN CENTRAL
LAKE MICHIGAN. OBSERVATIONS OVER AND NEAR THE LAKE INDICATE THE
PRESENCE OF GOOD CONVERGENCE ALONG THIS BOUNDARY. THE FIRST
MORNING VISIBLE SATELLITE IMAGES ALSO INDICATE CONVECTIVE
STRUCTURES DEVELOPING WITHIN THE BAND OF RAIN/SNOW SHOWERS
CURRENTLY SHIFTING SOUTHWARD JUST EAST OF MKE. OVERALL IT APPEARS
THIS AREA OF SNOWFALL WILL PIVOT SOUTHWARD ACROSS NORTHWESTERN
INDIANA WITHIN THE NEXT 2 HOURS (BY 1630Z). HOWEVER...I AM ALSO
CONCERNED THAT SOME OF THESE HEAVIER CONVECTIVE SNOW SHOWERS MAY
IMPACT PORTIONS OF NORTHEASTERN ILLINOIS...INCLUDING DOWNTOWN
CHICAGO THROUGH LATE MORNING. IN FACT...SOME OF THE LATEST RADAR
IMAGERY IS ALREADY INDICATING SOME BANDS OF PRECIP MOVING INTO
NORTHERN COOK COUNTY. IT APPEARS THE WINDS WILL BECOME MORE
NORTHERLY IN THE WAKE OF THIS SURFACE TROUGH...AND WIND SPEEDS
COULD ALSO INCREASE A BIT HIGHER THAN CURRENT WIND SPEEDS. WE WILL
CONTINUE TO WATCH OBSERVATION TRENDS...AND HANDLE THIS SNOWFALL
ACROSS THE CHICAGO AREA WITH GRAPHICAL NOWCASTS AT THIS TIME. IT
DOES APPEAR THIS INITIAL BURST OF SNOW WILL BE SOMEWHAT SHORT
LIVED ACROSS THE CHICAGO METRO AREA. WHILE SOME MINOR
ACCUMULATIONS ARE CERTAINLY POSSIBLE WITH THIS ACTIVITY...WE HAVE
NO IMMEDIATE PLANS TO EXPAND THE CURRENT WINTER WEATHER HEADLINES.

FOLLOWING THIS INITIAL BOUNDARY AND BURST OF SNOW...HI RES GUIDANCE
CONTINUES TO INDICATE THAT BANDS OF LAKE EFFECT RAIN/SNOW SHOWERS
WILL CONTINUE TO DEVELOP AND IMPACT MUCH OF THE AREAS CURRENTLY
UNDER THE WINTER HEADLINE ACROSS NORTHWESTERN INDIANA. HOWEVER...WE
WILL NEED TO WATCH FOR THE POTENTIAL OF THE LAKE EFFECT BANDS THIS
AFTERNOON TRYING TO WORK MORE WEST INTO EASTERN ILLINOIS. SOME
GUIDANCE DOES SUGGEST THAT THE LAKE EFFECT BANDS WILL EFFECT AREAS
NEAR...OR EVEN ALONG THE ILLINOIS...INDIANA STATE LINE....AND
POSSIBLY PARTS OF CHICAGO AS WELL. HOWEVER...GIVEN THE MODEL
DIFFERENCES...AND UNCERTAINTY STILL INHERENT IN WHERE ANY LAKE EFFECT
BAND...OR BANDS WILL SET UP...I WOULD LIKE TO WATCH THE EVOLUTION OF
CONDITIONS OVER THE LAKE BEFORE PUSHING SNOWFALL AMOUNTS...AND WINTER
HEADLINES FARTHER WEST.

NO BIG CHANGES ARE PLANNED FOR THE UPDATE. HOWEVER...I WILL LIKELY
ADD A MENTION OF LIGHT SNOW/FLURRIES FOR AREAS A BIT FARTHER INLAND
ACROSS NORTHEASTERN ILLINOIS BASED ON REPORTS OF LIGHT SNOW...AND
RADAR TRENDS.

KJB

&&

.AVIATION...

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

* OFF AND ON FLURRIES LATE THIS MORNING AND AFTERNOON WITH THE
  POSSIBILITY OF SOME TEMPORARY SNOW SHOWERS NAMELY AT MDW.

* NORTHWEST WINDS SHIFTING NORTH TOWARD 16Z-17Z WITH GUSTS OF 35
  TO 40 KT. GUST SPEEDS WILL BE ERRATIC AND 40 KT GUSTS SHOULD BE
  SPORADIC.

* PERIODIC MVFR CIGS THROUGH THE MORNING AND POSSIBLY INTO THE
  AFTERNOON...ALTHOUGH SHOULD REMAIN ABOVE 2000 FT.

* LAKE EFFECT SNOW SHOWERS COULD AFFECT MDW FROM EARLY EVENING
  ONWARD.

MTF/MDB

//DISCUSSION...UPDATED 14Z...

NORTH-NORTHWEST WINDS HAVE BEEN VERY STEADY AT 340-350 AT ORD AND
MDW. A SECONDARY COLD FRONT/TROUGH IS MOVING SOUTHWARD DOWN LAKE
MICHIGAN AND WISCONSIN AND THIS WILL TURN WINDS MORE DUE NORTH.
THIS IS SLIGHTLY LATER FOR DUE NORTH THAN PREVIOUS TAF. WIND SPEED
THINKING REMAINS THE SAME.

CONVECTIVE CLOUD TOPS ARE BEGINNING TO SHOW UP ACROSS THE CENTRAL
AND SOUTHERN PART OF THE LAKE SO IT IS POSSIBLE WE BEGIN TO SEE
SOME LIGHTNING AS WELL.

PREV DISCUSSION...UPDATED 12Z...

NORTHWEST WINDS HAVE BEEN STEADILY INCREASING EARLY THIS MORNING
AS STRONG HIGH PRESSURE APPROACHES FROM THE NORTHWEST. ONE UPPER
WAVE AND ASSOCIATED -SHRA IS DEPARTING WHILE ANOTHER IS APPROACHING
FROM THE NORTH. A PUSH OF COLDER AIR WITH THE NEXT WAVE IS
RESULTING IN A BAND OF SNOW SHOWERS WHICH HAS BEEN REDUCING VSBY
TO AROUND A MILE AT TIMES...AT LEAST BRIEFLY. EXPECT A 1-2 HR
WINDOW OF -SHSN AT THE TERMINALS OVER THE NEXT 2-3 HRS. VARIABLE
MVFR-VFR CIGS WILL CONTINUE THROUGH MUCH OF THE MORNING BEFORE
STEADIER VFR IS EXPECTED ACROSS THE ILLINOIS TERMINALS WITH
SCATTERING OF CLOUDS WEST.

WINDS WILL TURN TO THE NORTH WITH THE PASSAGE OF THE UPPER WAVE
THIS MORNING AND EXPECT TO SEE A SURGE IN GUSTS AT THAT TIME. 35
TO 40 KT GUSTS ARE EXPECTED BUT AM NOT HIGHLY CONFIDENT IN HOW
FREQUENTLY 40 KT MAY BE REACHED. IT APPEARS THAT MID MORNING MAY
BE ONE POTENTIALLY PRIME PERIOD BEHIND THE UPPER WAVE/PRECIP WITH
THE NEXT POTENTIALLY FAVORED TIME BEING MID AFTERNOON IF SKIES CAN
SCATTER. IT MAY BE THAT AN OCCASIONAL 40 KT GUST OCCURS AT ANY
POINT THROUGH THE DAY. WINDS WILL EASE THIS EVENING.

LAKE EFFECT PRECIPITATION IS EXPECTED TO DEVELOP MID TO LATE
MORNING AND FOCUS ACROSS NORTHWEST INDIANA WITH GYY POSSIBLY BEING
ON THE WESTERN FRINGE INITIALLY BUT LIKELY GETTING INTO THE PRIME
BANDING INTO THE AFTERNOON. GIVEN THEIR PROXIMITY TO THE FAIRLY
WARM LAKE A RAIN SNOW MIX IS FAVORED TURNING TO ALL SNOW IF VERY
INTENSE BANDING CAN OCCUR. THUNDER IS ALSO POSSIBLE AND WOULD
ENHANCE THE ALL SNOW POTENTIAL. AS A RESULT IFR VSBY WILL LIKELY
OCCUR AT TIMES BUT THERE ARE FACTORS THAT MAY LIMIT THE
ORGANIZATION OF THE PRECIP. WINDS WILL LIKELY GUST 40-45 KT WITH
50 NOT OUT OF THE QUESTION TOWARD MIDDAY. LAKE EFFECT PRECIP WILL
LIKELY TURN TO ALL SNOW THIS EVENING AND SHIFT WESTWARD TOWARD THE
IL/IN STATE LINE AND POSSIBLY BEGIN TO IMPACT MDW WITH LIGHT
ACCUMULATIONS POSSIBLE...MAINLY ON THE GRASS. SEVERAL HOURS OF
SNOW MAY OCCUR AT OR NEAR MDW. ADJUSTMENTS TO THE FORECAST DETAILS
THIS EVENING AT MDW/GYY AND EVEN ORD ARE LIKELY.

MDB

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

* LOW ON IF IFR SNOW SHOWERS MAY IMPACT MDW THIS AFTERNOON.
  MEDIUM THAT THEY WILL STAY EAST OF ORD.

* HIGH IN NORTHWEST WINDS TURNING DUE NORTH AND MEDIUM IN TIMING.
  HIGH IN WIND SPEEDS AND THAT ANY GUSTS TO 40 KT WILL BE
  TEMPORARY.

* MEDIUM IN MVFR CIGS. HIGH THAT THEY WILL REMAIN ABOVE 2000 FT
  AT ORD...MEDIUM AT MDW.

* MEDIUM IN LAKE EFFECT SNOW SHOWER POTENTIAL TONIGHT AT MDW...LOW
  AT ORD.

MTF/MDB

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

* SATURDAY NIGHT...DRY VFR. LIGHT/VARIABLE WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS 10-15 KT.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.
* TUESDAY...SHRA/MVFR LIKELY. SOUTHWEST WINDS.
* WEDNESDAY...DRY/VFR. SOUTHWEST WINDS.
* THURSDAY...DRY/VFR. WEST WINDS.

MDB

&&

.MARINE...
256 AM CDT

A MAJOR WIND EVENT CONTINUES TO TAKE SHAPE FOR LAKE MICHIGAN EARLY
THIS MORNING. FAIRLY BROAD LOW PRESSURE OVER LAKE HURON WILL TRACK
SOUTHEAST TO LAKE ERIE BY MIDDAY THEN CONTINUE TO THE CAROLINA COAST
TONIGHT AND MERGE WITH DEVELOPING LOW PRESSURE. VERY STRONG HIGH
PRESSURE STRETCHED ACROSS THE NORTHERN PLAINS INTO CENTRAL CANADA IS
THE KEY TO THE RAPIDLY INCREASING WINDS THAT ARE NOW REACHING THE
NORTHERN PORTION OF THE LAKE. THE PRESSURE GRADIENT WILL QUICKLY
INCREASE ACROSS THE LAKE INTO MID MORNING AS A COLD FRONT SWEEPS
ACROSS ALLOWING MUCH COLDER AIR TO SPREAD DOWN THE LAKE. NORTH WINDS
WILL LIKELY INCREASE TO STORM FORCE AROUND 50 KT FOR MOST OF THE
LAKE WITH THE FAR NORTHERN SECTION HOLDING AT GALES...THOUGH A FEW
50 KT GUSTS COULD OCCUR THIS MORNING. MAY SEE SOME 55 KT GUSTS AT
TIMES ACROSS THE SOUTH HALF OF THE LAKE...ESPECIALLY LATE THIS
MORNING INTO MIDDAY. THIS RAPID INCREASE IN WINDS AND STRONG
MIXING OVER THE LAKE WILL ALLOW FOR A RAPID BUILDING OF WAVES
THROUGH THE MORNING TO AROUND 20 FEET BY EARLY/MID AFTERNOON
ACROSS THE CENTRAL AND SOUTHERN PART OF THE LAKE. WILL CONTINUE
WITH 18-23 FT PREVAILING WAVES IN THE FORECAST FOR THESE AREAS.
WINDS WILL BEGIN TO EASE THIS EVENING AND TREND A BIT
NORTHEASTERLY. SHOULD SEE WINDS FALL BELOW GALE FORCE OVERNIGHT
BUT WINDS WILL BE SLOW TO DIMINISH SIGNIFICANTLY THROUGH MIDDAY
SATURDAY SO WAVES WILL LIKELY BE SLOW TO FALL AS WELL. WILL LEAVE
EXISTING GALE AND STORM WARNINGS AS-IS.

THE HIGH WILL PASS OVER THE LAKE SATURDAY EVENING THROUGH SUNDAY
KEEPING WINDS LIGHT BUT SOUTH TO SOUTHWEST WINDS WILL INCREASE
THROUGH THE DAY SUNDAY AND MAY PUSH 30 KT LATE SUNDAY
AFTERNOON/EVENING AS LOW PRESSURE TRACKS NORTHEAST ACROSS THE
NORTHERN PLAINS. SOUTHWEST WINDS WILL REMAIN STRONG THROUGH MONDAY
NIGHT THEN LET UP NORTH AS LOW PRESSURE TRACKS FROM THE SOUTHERN
PLAINS ACROSS NORTHERN LAKE MICHIGAN...WHILE THE SOUTH SEES BREEZY
CONDITIONS CONTINUE. WINDS TURN WESTERLY LATER TUESDAY AND
DIMINISH AS HIGH PRESSURE RIDGING EXTENDS ACROSS THE AREA.

MDB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HIGH WIND WARNING...ILZ014 UNTIL 6 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014 UNTIL 4 AM SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022-ILZ023-
     ILZ033 UNTIL 7 PM FRIDAY.

IN...HIGH WIND WARNING...INZ001-INZ002 UNTIL 6 PM FRIDAY.

     LAKE EFFECT SNOW ADVISORY...INZ001-INZ002-INZ010-INZ011 UNTIL 10
     PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...INZ001-INZ002 UNTIL 4 AM SATURDAY.

     WIND ADVISORY...INZ010-INZ011-INZ019 UNTIL 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 PM FRIDAY TO
     4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563 UNTIL 10 PM FRIDAY.

     GALE WARNING...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 4 AM SATURDAY.

&&

$$

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

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








000
FXUS63 KLOT 311422
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
922 AM CDT FRI OCT 31 2014

.SHORT TERM...
326 AM CDT

THROUGH SATURDAY...

ACTIVE WEATHER ON TAP THE NEXT 24 HOURS AS COMPACT AND DEEP UPPER
LOW DIVES SOUTH ACROSS THE REGION DRAGGING UNSEASONABLY COLD
AIR...BOTH AT THE SURFACE AND ALOFT...INTO THE REGION TODAY INTO
TONIGHT. EARLY THIS MORNING SURFACE ANALYSIS SHOWS A RATHER DIFFUSE
COLD FRONT MOVING ACROSS THE REGION WITH STRONG COLD ADVECTION
RESULTING IN A HEALTHY TEMP DROP PRIOR TO SUNRISE OVER NORTHERN CWA
AND SHORTLY AFTERWARD SOUTHEAST. STRONG NNW WINDS WILL ALSO ARRIVE
WITH THE COLD AIR AND CONTINUE INTO THIS EVENING RESULTING IN
TEMPERATURES LARGELY REMAINING FAIRLY STEADY THROUGH THE AFTERNOON.

COMPACT VORT AND REALLY THE HEART OF THE UPPER LOW SHOWS UP NICELY
OVER NORTHERN WISCONSIN EARLY THIS MORNING AND IS DIVING SSE TOWARD
THE AREA. THE COMBINATION OF ASCENT WITH THIS FEATURE AND STEEP
LAPSE RATES ARE RESULTING IN SCATTERED BUT FAIRLY VIGOROUS SNOW
SHOWERS OVER NORTHERN AND CENTRAL WISCONSIN AND WOULD FULLY
ANTICIPATE THESE TO MAINTAIN THEMSELVES AND MOVE ACROSS MAINLY THE
EASTERN CWA THIS MORNING. TEMPS WILL PROBABLY BE TOO WARM FOR MUCH
IF ANY ACCUMULATION...BUT SOME OF THE SNOW SHOWERS COULD BE BRIEFLY
VIGOROUS AND KNOCK VSBY DOWN TO BELOW 1SM. AS THE VORT CONTINUE
SOUTHEAST LOOK FOR THE NON-LAKE DRIVEN PRECIP TO END BY MID MORNING
NORTHERN CWA AND LATE MORNING SOUTHEAST CWA.

THE VORT WILL HERALD THE ARRIVAL OF THE COLDEST AIR ALOFT AND
RESULTANT STRONGEST INSTABILITY OVER THE LAKE AS H5 TEMPS DROP TO
-33C AND H7 TEMPS BELOW -15C. THERMODYNAMIC PROFILES OVER THE LAKE
BEHIND THIS VORT BECOME EXPLOSIVELY UNSTABLE THIS MORNING REMAIN SO
THROUGH THE DAY. LAKE EFFECT SHOULD GET GOING IN ERNEST BEHIND THIS
VORT AND CONTINUE TO SOME DEGREE INTO SATURDAY MORNING. FORECAST
LAKE INDUCED EQUILIBRIUM LEVELS TODAY APPROACH 20K FT...NEAR THE
-30C LEVEL...WHICH IS MORE THAN COLD ENOUGH TO SUPPORT LIGHTNING
GIVEN THE HIGH LIKELIHOOD OF MIXED PHASE HYDROMETEORS (SUPERCOOLED
DROPLETS AND ICE) IN THE CLOUDS WITHIN STRONG UPDRAFTS. NEAR SURFACE
TEMPS OVER THE LAKE AND WITHIN A FEW MILES OF THE LAKE SHORE MAY BE
WARM ENOUGH TO SUPPORT P-TYPE FLUCTUATING BETWEEN RAIN...RAIN/SNOW
MIX...AND ALL SNOW. LAKE EFFECT PRECIP FARTHER INLAND STANDS A MUCH
BETTER CHANCE OF REMAINING ALL OR MOSTLY SNOW.

ONE OF THE BIGGER UNCERTAINTIES FOR TODAY IS HOW ORGANIZED THE LAKE
EFFECT WILL BECOME AND WHETHER IT WILL BE MULTIPLE BANDS OR A SINGLE
INTENSE BAND. GIVEN THE VERY STRONG BOUNDARY LAYER WINDS AND LESS
THAN IDEAL TIME OF DAY AM CONCERNED THAT THE LAKE EFFECT PRECIP
COULD BE SOMEWHAT UNORGANIZED/SCATTERED IN NATURE WITH MULTIPLE
BANDS DURING THE DAY WHICH WILL BE THE TIME OF STRONG TO EXTREME
INSTABILITY. IF A MORE ORGANIZED DOMINANT SINGLE BAND DOES
FORM...THE STRONG FLOW AND INSTABILITY WELL INLAND WOULD SUPPORT
INTENSE PRECIP RATES MAKING IT WELL INLAND THIS AFTERNOON WHERE
P-TYPE WOULD LIKELY BE MOSTLY SNOW...POSSIBLY MODERATE TO HEAVY
SNOW. IF SNOW FALLS HEAVY ENOUGH THEN THE WARM GROUND TEMPS WOULD
BECOME MORE OF A MOOT POINT WITH RAPID ACCUMULATIONS OF HEAVY/WET
SNOW...ESPECIALLY ON GRASSY SURFACES WHERE ISOLATED LOCATIONS COULD
SEE A QUICK SEVERAL INCHES OF SNOW. THE MOST LIKELY SCENARIO WOULD
APPEAR TO BE SOMEWHAT LESS ORGANIZED BANDS OF SNOW SHOWERS RESULTING
IN ONLY MINOR ACCUMS ON GRASSY SURFACES IN SPOTS TODAY. THE WIND
WILL BE WHIPPING THE SNOW AROUND REGARDLESS SO UNDERNEATH ANY LAKE
EFFECT SNOW CONDITIONS WILL BE PRETTY MISERABLE EVEN THOUGH IT IS
UNLIKELY TO ACCUMULATE ON ROADS/SIDEWALKS TODAY. LAKE AND PORTER
COUNTY LOOK TO BE GROUND ZERO FOR THE LAKE EFFECT TODAY WITH THE
PRECIP LIKELY MAKING IT WELL INLAND TO JASPER AND NEWTON COUNTIES.
SOME HIGH RES GUIDANCE DOES CLIP SE COOK AND EASTERN WILL WITH LAKE
EFFECT PRECIP TODAY WHICH ISNT OUT OF THE QUESTION AND HAVE
MAINTAINED LOW POPS THERE.

THIS EVENING THE LOW LEVEL FLOW WILL GRADUALLY VEER AND SEND THE
LAKE EFFECT MORE INTO EASTERN COOK/EASTERN WILL/WESTERN LAKE IN (AND
EVEN POINTS SOUTH. BY THIS EVENING THE BOUNDARY LAYER FLOW WILL BE
WEAKENING AND THE TEMPS OUTSIDE OF THE LAKE INFLUENCED AREAS
DROPPING WHICH WOULD BOTH TEND TO FAVOR A TRANSITION TO A MORE
ORGANIZED DOMINANT SINGLE LAKE EFFECT BAND. MY BEST GUESS IS THAT
THE TIME WINDOW FOR THE HIGHEST PROBABILITY OF A DOMINANT LAKE
EFFECT BAND WITH POTENTIAL FOR HEAVY SNOW IS BETWEEN 23Z AND ABOUT
04Z. DURING THIS TIME PERIOD THE INSTABILITY (WHILE LESS THAN
EARLIER IN THE DAY) WILL STILL BE STRONG WITH INVERSION HEIGHTS
AROUND 10K FT AND LAKE-850 DELTA T VALUES >20C. DOES APPEARS A
PERIOD OF HEAVY SNOW COULD OCCUR IN EASTERN/SOUTHEASTERN COOK AND
EASTERN WILL COUNTIES EARLY THIS EVENING...BUT GIVEN THE LOW
CONFIDENCE OPTED NOT TO EXPAND THE WINTER WX HEADLINES AT THIS TIME
AND INSTEAD WILL ALLOW DAY SHIFT TO MONITOR MESOSCALE TRENDS. BY
LATER THIS EVENING INTO THE OVERNIGHT HOURS THE LAKE EFFECT
PARAMETERS WILL CONTINUE TO BECOME LESS FAVORABLE AND THE INTENSITY
OF THE LAKE EFFECT PRECIP SHOULD BEGIN TO WIND DOWN LATE TONIGHT AND
EVENTUALLY END SATURDAY. HAVE EXTENDED THE HIGHER POPS LATER IN TIME
AS LAKE EFFECT RARELY WINDS DOWN AS QUICKLY AS MODEL PROGGED
PARAMETERS SUGGEST IT WILL. WORTH NOTING THAT BY LATE EVENING AND
THROUGH SAT MORNING THE CONVECTIVE CLOUD TOP TEMPS DROP BELOW -12C
MEANING THE LIKELIHOOD OF CLOUDS CONTAINING ICE NUCLEI FOR SNOW WILL
BE LOW...SO DESPITE LOWER TEMPS IN THE BOUNDARY LAYER HAVE
TRANSITIONED P-TYPE BACK TO RAIN OR SNOW LATE TONIGHT AND SAT
MORNING.

FINALLY...HIGH WINDS WILL BE THE OTHER CONCERN TODAY. PLAN TO
MAINTAIN WIND ADVISORY AS IS THOUGH CONFIDENCE IN INLAND LOCATIONS
REACHING ADVISORY CRITERIA IS NOT THAT HIGH...BUT WITH GUSTS TO AT
LEAST 40 MPH A GOOD BET NOTHING WOULD BE GAINED FROM MAKING ANY
CHANGES TO THE HEADLINES. THE STORM WARNING FOR THE LAKE LOOKS
LIKELY TO VERIFY WITH 40 MPH SUSTAINED AND POSSIBLY GUSTS TO 58 MPH
LIKELY ALONG THE LAKE FRONT TODAY AND REALLY NOT COMFORTABLE NOT
HAVING A WARNING WITH THE POTENTIAL FOR DAMAGING WINDS ALONG THE
LAKE...SO AM GOING TO UPGRADE TO A HIGH WIND WARNING FOR LAKE SHORE
AREAS.

HEADLINES ARE AN ABSOLUTE MESS AND HEADACHE. WINTER WX ADVISORY
COVERS WIND AND SNOW...BUT IN ORDER TO GO WITH WARNING FOR WIND
ALONG THE LAKE FRONT IN INDIANA WOULD NEED TO UPGRADE TO A WINTER
STORM WARNING WHICH REALLY DOESNT SEEM TO BE THE BEST PRODUCT. AFTER
MUCH HEMMING AND HAWING AND INTERNAL COORDINATION HAVE OPTED TO
CHANGE THE WINTER WX ADV TO A LAKE EFFECT SNOW ADVISORY AND ISSUE A
WIND ADVISORY FOR JASPER AND NEWTON AND A HIGH WIND WARNING FOR LAKE
SHORE AREAS OF COOK...PORTER...AND LAKE IN. MAY NEED TO REPLACE THE
HIGH WIND WARNING WITH A WIND ADVISORY BY EARLY EVENING FOR

IZZI

&&

.LONG TERM...
325 AM CDT

SATURDAY NIGHT THROUGH THURSDAY...

MUCH...MUCH QUIETER SUNDAY AND MONDAY WITH MODERATING TEMPS. SLOW
MOVING FRONT COULD BRING A SOMEWHAT PROLONGED PERIOD OF RAIN/SHOWERS
MONDAY NIGHT THOUGH TUESDAY NIGHT. GENERALLY SEASONABLE TEMPS
EXPECTED THROUGH THE EXTENDED.

IZZI

&&

.AVIATION...

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

* OFF AND ON FLURRIES LATE THIS MORNING AND AFTERNOON WITH THE
  POSSIBILITY OF SOME TEMPORARY SNOW SHOWERS NAMELY AT MDW.

* NORTHWEST WINDS SHIFTING NORTH TOWARD 16Z-17Z WITH GUSTS OF 35
  TO 40 KT. GUST SPEEDS WILL BE ERRATIC AND 40 KT GUSTS SHOULD BE
  SPORADIC.

* PERIODIC MVFR CIGS THROUGH THE MORNING AND POSSIBLY INTO THE
  AFTERNOON...ALTHOUGH SHOULD REMAIN ABOVE 2000 FT.

* LAKE EFFECT SNOW SHOWERS COULD AFFECT MDW FROM EARLY EVENING
  ONWARD.

MTF/MDB

//DISCUSSION...UPDATED 14Z...

NORTH-NORTHWEST WINDS HAVE BEEN VERY STEADY AT 340-350 AT ORD AND
MDW. A SECONDARY COLD FRONT/TROUGH IS MOVING SOUTHWARD DOWN LAKE
MICHIGAN AND WISCONSIN AND THIS WILL TURN WINDS MORE DUE NORTH.
THIS IS SLIGHTLY LATER FOR DUE NORTH THAN PREVIOUS TAF. WIND SPEED
THINKING REMAINS THE SAME.

CONVECTIVE CLOUD TOPS ARE BEGINNING TO SHOW UP ACROSS THE CENTRAL
AND SOUTHERN PART OF THE LAKE SO IT IS POSSIBLE WE BEGIN TO SEE
SOME LIGHTNING AS WELL.


PREV DISCUSSION...UPDATED 12Z...

NORTHWEST WINDS HAVE BEEN STEADILY INCREASING EARLY THIS MORNING
AS STRONG HIGH PRESSURE APPROACHES FROM THE NORTHWEST. ONE UPPER
WAVE AND ASSOCIATED -SHRA IS DEPARTING WHILE ANOTHER IS APPROACHING
FROM THE NORTH. A PUSH OF COLDER AIR WITH THE NEXT WAVE IS
RESULTING IN A BAND OF SNOW SHOWERS WHICH HAS BEEN REDUCING VSBY
TO AROUND A MILE AT TIMES...AT LEAST BRIEFLY. EXPECT A 1-2 HR
WINDOW OF -SHSN AT THE TERMINALS OVER THE NEXT 2-3 HRS. VARIABLE
MVFR-VFR CIGS WILL CONTINUE THROUGH MUCH OF THE MORNING BEFORE
STEADIER VFR IS EXPECTED ACROSS THE ILLINOIS TERMINALS WITH
SCATTERING OF CLOUDS WEST.

WINDS WILL TURN TO THE NORTH WITH THE PASSAGE OF THE UPPER WAVE
THIS MORNING AND EXPECT TO SEE A SURGE IN GUSTS AT THAT TIME. 35
TO 40 KT GUSTS ARE EXPECTED BUT AM NOT HIGHLY CONFIDENT IN HOW
FREQUENTLY 40 KT MAY BE REACHED. IT APPEARS THAT MID MORNING MAY
BE ONE POTENTIALLY PRIME PERIOD BEHIND THE UPPER WAVE/PRECIP WITH
THE NEXT POTENTIALLY FAVORED TIME BEING MID AFTERNOON IF SKIES CAN
SCATTER. IT MAY BE THAT AN OCCASIONAL 40 KT GUST OCCURS AT ANY
POINT THROUGH THE DAY. WINDS WILL EASE THIS EVENING.

LAKE EFFECT PRECIPITATION IS EXPECTED TO DEVELOP MID TO LATE
MORNING AND FOCUS ACROSS NORTHWEST INDIANA WITH GYY POSSIBLY BEING
ON THE WESTERN FRINGE INITIALLY BUT LIKELY GETTING INTO THE PRIME
BANDING INTO THE AFTERNOON. GIVEN THEIR PROXIMITY TO THE FAIRLY
WARM LAKE A RAIN SNOW MIX IS FAVORED TURNING TO ALL SNOW IF VERY
INTENSE BANDING CAN OCCUR. THUNDER IS ALSO POSSIBLE AND WOULD
ENHANCE THE ALL SNOW POTENTIAL. AS A RESULT IFR VSBY WILL LIKELY
OCCUR AT TIMES BUT THERE ARE FACTORS THAT MAY LIMIT THE
ORGANIZATION OF THE PRECIP. WINDS WILL LIKELY GUST 40-45 KT WITH
50 NOT OUT OF THE QUESTION TOWARD MIDDAY. LAKE EFFECT PRECIP WILL
LIKELY TURN TO ALL SNOW THIS EVENING AND SHIFT WESTWARD TOWARD THE
IL/IN STATE LINE AND POSSIBLY BEGIN TO IMPACT MDW WITH LIGHT
ACCUMULATIONS POSSIBLE...MAINLY ON THE GRASS. SEVERAL HOURS OF
SNOW MAY OCCUR AT OR NEAR MDW. ADJUSTMENTS TO THE FORECAST DETAILS
THIS EVENING AT MDW/GYY AND EVEN ORD ARE LIKELY.

MDB

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

* LOW ON IF IFR SNOW SHOWERS MAY IMPACT MDW THIS AFTERNOON.
  MEDIUM THAT THEY WILL STAY EAST OF ORD.

* HIGH IN NORTHWEST WINDS TURNING DUE NORTH AND MEDIUM IN TIMING.
  HIGH IN WIND SPEEDS AND THAT ANY GUSTS TO 40 KT WILL BE
  TEMPORARY.

* MEDIUM IN MVFR CIGS. HIGH THAT THEY WILL REMAIN ABOVE 2000 FT
  AT ORD...MEDIUM AT MDW.

* MEDIUM IN LAKE EFFECT SNOW SHOWER POTENTIAL TONIGHT AT MDW...LOW
  AT ORD.

MTF/MDB


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

* SATURDAY NIGHT...DRY VFR. LIGHT/VARIABLE WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS 10-15 KT.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.
* TUESDAY...SHRA/MVFR LIKELY. SOUTHWEST WINDS.
* WEDNESDAY...DRY/VFR. SOUTHWEST WINDS.
* THURSDAY...DRY/VFR. WEST WINDS.

MDB

&&

.MARINE...
256 AM CDT

A MAJOR WIND EVENT CONTINUES TO TAKE SHAPE FOR LAKE MICHIGAN EARLY
THIS MORNING. FAIRLY BROAD LOW PRESSURE OVER LAKE HURON WILL TRACK
SOUTHEAST TO LAKE ERIE BY MIDDAY THEN CONTINUE TO THE CAROLINA COAST
TONIGHT AND MERGE WITH DEVELOPING LOW PRESSURE. VERY STRONG HIGH
PRESSURE STRETCHED ACROSS THE NORTHERN PLAINS INTO CENTRAL CANADA IS
THE KEY TO THE RAPIDLY INCREASING WINDS THAT ARE NOW REACHING THE
NORTHERN PORTION OF THE LAKE. THE PRESSURE GRADIENT WILL QUICKLY
INCREASE ACROSS THE LAKE INTO MID MORNING AS A COLD FRONT SWEEPS
ACROSS ALLOWING MUCH COLDER AIR TO SPREAD DOWN THE LAKE. NORTH WINDS
WILL LIKELY INCREASE TO STORM FORCE AROUND 50 KT FOR MOST OF THE
LAKE WITH THE FAR NORTHERN SECTION HOLDING AT GALES...THOUGH A FEW
50 KT GUSTS COULD OCCUR THIS MORNING. MAY SEE SOME 55 KT GUSTS AT
TIMES ACROSS THE SOUTH HALF OF THE LAKE...ESPECIALLY LATE THIS
MORNING INTO MIDDAY. THIS RAPID INCREASE IN WINDS AND STRONG
MIXING OVER THE LAKE WILL ALLOW FOR A RAPID BUILDING OF WAVES
THROUGH THE MORNING TO AROUND 20 FEET BY EARLY/MID AFTERNOON
ACROSS THE CENTRAL AND SOUTHERN PART OF THE LAKE. WILL CONTINUE
WITH 18-23 FT PREVAILING WAVES IN THE FORECAST FOR THESE AREAS.
WINDS WILL BEGIN TO EASE THIS EVENING AND TREND A BIT
NORTHEASTERLY. SHOULD SEE WINDS FALL BELOW GALE FORCE OVERNIGHT
BUT WINDS WILL BE SLOW TO DIMINISH SIGNIFICANTLY THROUGH MIDDAY
SATURDAY SO WAVES WILL LIKELY BE SLOW TO FALL AS WELL. WILL LEAVE
EXISTING GALE AND STORM WARNINGS AS-IS.

THE HIGH WILL PASS OVER THE LAKE SATURDAY EVENING THROUGH SUNDAY
KEEPING WINDS LIGHT BUT SOUTH TO SOUTHWEST WINDS WILL INCREASE
THROUGH THE DAY SUNDAY AND MAY PUSH 30 KT LATE SUNDAY
AFTERNOON/EVENING AS LOW PRESSURE TRACKS NORTHEAST ACROSS THE
NORTHERN PLAINS. SOUTHWEST WINDS WILL REMAIN STRONG THROUGH MONDAY
NIGHT THEN LET UP NORTH AS LOW PRESSURE TRACKS FROM THE SOUTHERN
PLAINS ACROSS NORTHERN LAKE MICHIGAN...WHILE THE SOUTH SEES BREEZY
CONDITIONS CONTINUE. WINDS TURN WESTERLY LATER TUESDAY AND
DIMINISH AS HIGH PRESSURE RIDGING EXTENDS ACROSS THE AREA.

MDB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HIGH WIND WARNING...ILZ014 UNTIL 6 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014 UNTIL 4 AM SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022-ILZ023-
     ILZ033 UNTIL 7 PM FRIDAY.

IN...HIGH WIND WARNING...INZ001-INZ002 UNTIL 6 PM FRIDAY.

     LAKE EFFECT SNOW ADVISORY...INZ001-INZ002-INZ010-INZ011 UNTIL 10
     PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...INZ001-INZ002 UNTIL 4 AM SATURDAY.

     WIND ADVISORY...INZ010-INZ011-INZ019 UNTIL 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 PM FRIDAY TO
     4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563 UNTIL 10 PM FRIDAY.

     GALE WARNING...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 4 AM SATURDAY.

&&

$$

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

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






000
FXUS63 KILX 311159
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
659 AM CDT Fri Oct 31 2014

.SHORT TERM...(Today)
ISSUED AT 330 AM CDT FRI OCT 31 2014

The passage of a strong cold front and upper level shortwave will
highlight the short term forecast. At 08z/3am the front had already
reached near the Illinois River Valley, with the upper wave centered
behind the front across Wisconsin. Very gusty northwest winds were
lagging behind the front by a couple of hours, so winds in our
counties will begin to increase by around sunrise, especially NW of
Lincoln. Wind gusts this afternoon will climb into the 30-40 mph
range, especially east of Peoria to Springfield. Spotty rain showers
or sprinkles were developing just ahead of the front, generally
along and east of the I-55 corridor at 3 am.

Spotty showers will continue to advance eastward with the front
today, then linger this afternoon as the upper level shortwave
affects eastern Illinois. As colder air arrives on brisk northwest
winds today, some of the light rain showers could change over to
snow showers for areas east of Champaign and north of Paris.

Highs today will likely occur this morning, as the colder air and
cloud cover prevent temperatures from rising much this afternoon.
Temps will likely become steady or slowly fall by midday in most
areas.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 330 AM CDT FRI OCT 31 2014

A potent Canadian shortwave will dive sse from Lake Superior and WI
across IN/KY tonight. North-northwest winds 20-30 mph with gusts
30-40 mph will diminish to 10-15 mph overnight with gusts up to 20
mph. This will advect in subfreezing temperatures of 25-30F and
bring a killing freeze to much of IL overnight until mid morning
Saturday. Will continue the freezing warning overnight until 9 am
Sat for central and southeast IL. Moisture flow off Lake MI could
bring a few snow showers near the IN border especially over
Vermilion county this evening. A taste of early winter weather for
Halloween Trick or Treaters this evening with wind chills slipping
into the low to mid 20s. Chilly highs in the mid 40s Saturday
despite a fair amount of sunshine, due to north winds 8-15 mph and
gusts 15 to 20 mph over eastern IL.

Strong Canadian high pressure of 1039 mb over ND will settle over IL
Saturday night as it slowly weakens with fair skies and light winds.
This will bring another hard freeze overnight Saturday night and
early Sunday morning with lows in the middle to upper 20s, and
coldest east of I-57. Mostly sunny skies Sunday but still chilly
highs in the upper 40s to around 50F.

More unsettled weather pattern takes shape Monday-Wednesday as IL
gets in a southwesterly upper level flow with upper level ridge
shifting east of IL and strong upper level trof digging into the
southern Rockies. A frontal boundary will set up from the southern
Plains ne into the Ohio river valley Monday night through Wed and
bring increasing chances of showers. Cold front to move se across
central IL Tue when best chances of showers and isolated
thunderstorms will be. Have 20-30% chance of showers by Monday
afternoon west of I-55 as clouds increasing from the west during the
day. Then likely chances of showers develop during Monday night into
Tue and highest pops shift into southeast IL during Tue night and
Wed. Milder highs in the upper 50s and lower 60s Monday and 55-60F
Tue and Wed. Isolated thunderstorms may also occur Monday night and
Tue south of I-72. Slight chance of showers in southeast IL Wed
evening, otherwise drier weather is expected Wed night thru Friday
as dry west northwesterly flow trails the system with seasonable
highs still in the mid to upper 50s and near 60F in southeast IL.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
ISSUED AT 659 AM CDT FRI OCT 31 2014

A brief period of MVFR clouds around 2k FT will affect DEC and CMI
through 13-14z before mixing lifts the cloud deck into the VFR
range. Then VFR conditions will prevail the remainder of the TAF
forecast. NW winds will increase early this morning with sustained
20-25kt and gusts to near 40kt at times by 16-17z.

The leading edge of a strong shortwave aloft could trigger a few
rain or snow showers between 14z and 18z for the northern taf
sights of PIA/BMI/CMI. Any snow would melt as it falls. Otherwise,
precipitation should be minimal at all TAF sites over the next 24
hours. Latest HRRR forecast indicates the stratocumulus should
begin to decrease in coverage and affect mainly areas east of I55
by afternoon as subsidence develops in the wake of the upper level
shortwave. Skies should become clear even over eastern areas
after 00z tonight. Surface winds will gradually diminish,
especially the gusts, toward evening with sustained winds of
12-15 kts after 02z.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING from Midnight tonight to 9 AM CDT Saturday FOR
ILZ027>031-036>038-040>057-061>063-066>068-071>073.

&&

$$

SHORT TERM...Shimon
LONG TERM...07
AVIATION...Shimon







000
FXUS63 KLOT 311150
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
650 AM CDT FRI OCT 31 2014

.SHORT TERM...
326 AM CDT

THROUGH SATURDAY...

ACTIVE WEATHER ON TAP THE NEXT 24 HOURS AS COMPACT AND DEEP UPPER
LOW DIVES SOUTH ACROSS THE REGION DRAGGING UNSEASONABLY COLD
AIR...BOTH AT THE SURFACE AND ALOFT...INTO THE REGION TODAY INTO
TONIGHT. EARLY THIS MORNING SURFACE ANALYSIS SHOWS A RATHER DIFFUSE
COLD FRONT MOVING ACROSS THE REGION WITH STRONG COLD ADVECTION
RESULTING IN A HEALTHY TEMP DROP PRIOR TO SUNRISE OVER NORTHERN CWA
AND SHORTLY AFTERWARD SOUTHEAST. STRONG NNW WINDS WILL ALSO ARRIVE
WITH THE COLD AIR AND CONTINUE INTO THIS EVENING RESULTING IN
TEMPERATURES LARGELY REMAINING FAIRLY STEADY THROUGH THE AFTERNOON.

COMPACT VORT AND REALLY THE HEART OF THE UPPER LOW SHOWS UP NICELY
OVER NORTHERN WISCONSIN EARLY THIS MORNING AND IS DIVING SSE TOWARD
THE AREA. THE COMBINATION OF ASCENT WITH THIS FEATURE AND STEEP
LAPSE RATES ARE RESULTING IN SCATTERED BUT FAIRLY VIGOROUS SNOW
SHOWERS OVER NORTHERN AND CENTRAL WISCONSIN AND WOULD FULLY
ANTICIPATE THESE TO MAINTAIN THEMSELVES AND MOVE ACROSS MAINLY THE
EASTERN CWA THIS MORNING. TEMPS WILL PROBABLY BE TOO WARM FOR MUCH
IF ANY ACCUMULATION...BUT SOME OF THE SNOW SHOWERS COULD BE BRIEFLY
VIGOROUS AND KNOCK VSBY DOWN TO BELOW 1SM. AS THE VORT CONTINUE
SOUTHEAST LOOK FOR THE NON-LAKE DRIVEN PRECIP TO END BY MID MORNING
NORTHERN CWA AND LATE MORNING SOUTHEAST CWA.

THE VORT WILL HERALD THE ARRIVAL OF THE COLDEST AIR ALOFT AND
RESULTANT STRONGEST INSTABILITY OVER THE LAKE AS H5 TEMPS DROP TO
-33C AND H7 TEMPS BELOW -15C. THERMODYNAMIC PROFILES OVER THE LAKE
BEHIND THIS VORT BECOME EXPLOSIVELY UNSTABLE THIS MORNING REMAIN SO
THROUGH THE DAY. LAKE EFFECT SHOULD GET GOING IN ERNEST BEHIND THIS
VORT AND CONTINUE TO SOME DEGREE INTO SATURDAY MORNING. FORECAST
LAKE INDUCED EQUILIBRIUM LEVELS TODAY APPROACH 20K FT...NEAR THE
-30C LEVEL...WHICH IS MORE THAN COLD ENOUGH TO SUPPORT LIGHTNING
GIVEN THE HIGH LIKELIHOOD OF MIXED PHASE HYDROMETEORS (SUPERCOOLED
DROPLETS AND ICE) IN THE CLOUDS WITHIN STRONG UPDRAFTS. NEAR SURFACE
TEMPS OVER THE LAKE AND WITHIN A FEW MILES OF THE LAKE SHORE MAY BE
WARM ENOUGH TO SUPPORT P-TYPE FLUCTUATING BETWEEN RAIN...RAIN/SNOW
MIX...AND ALL SNOW. LAKE EFFECT PRECIP FARTHER INLAND STANDS A MUCH
BETTER CHANCE OF REMAINING ALL OR MOSTLY SNOW.

ONE OF THE BIGGER UNCERTAINTIES FOR TODAY IS HOW ORGANIZED THE LAKE
EFFECT WILL BECOME AND WHETHER IT WILL BE MULTIPLE BANDS OR A SINGLE
INTENSE BAND. GIVEN THE VERY STRONG BOUNDARY LAYER WINDS AND LESS
THAN IDEAL TIME OF DAY AM CONCERNED THAT THE LAKE EFFECT PRECIP
COULD BE SOMEWHAT UNORGANIZED/SCATTERED IN NATURE WITH MULTIPLE
BANDS DURING THE DAY WHICH WILL BE THE TIME OF STRONG TO EXTREME
INSTABILITY. IF A MORE ORGANIZED DOMINANT SINGLE BAND DOES
FORM...THE STRONG FLOW AND INSTABILITY WELL INLAND WOULD SUPPORT
INTENSE PRECIP RATES MAKING IT WELL INLAND THIS AFTERNOON WHERE
P-TYPE WOULD LIKELY BE MOSTLY SNOW...POSSIBLY MODERATE TO HEAVY
SNOW. IF SNOW FALLS HEAVY ENOUGH THEN THE WARM GROUND TEMPS WOULD
BECOME MORE OF A MOOT POINT WITH RAPID ACCUMULATIONS OF HEAVY/WET
SNOW...ESPECIALLY ON GRASSY SURFACES WHERE ISOLATED LOCATIONS COULD
SEE A QUICK SEVERAL INCHES OF SNOW. THE MOST LIKELY SCENARIO WOULD
APPEAR TO BE SOMEWHAT LESS ORGANIZED BANDS OF SNOW SHOWERS RESULTING
IN ONLY MINOR ACCUMS ON GRASSY SURFACES IN SPOTS TODAY. THE WIND
WILL BE WHIPPING THE SNOW AROUND REGARDLESS SO UNDERNEATH ANY LAKE
EFFECT SNOW CONDITIONS WILL BE PRETTY MISERABLE EVEN THOUGH IT IS
UNLIKELY TO ACCUMULATE ON ROADS/SIDEWALKS TODAY. LAKE AND PORTER
COUNTY LOOK TO BE GROUND ZERO FOR THE LAKE EFFECT TODAY WITH THE
PRECIP LIKELY MAKING IT WELL INLAND TO JASPER AND NEWTON COUNTIES.
SOME HIGH RES GUIDANCE DOES CLIP SE COOK AND EASTERN WILL WITH LAKE
EFFECT PRECIP TODAY WHICH ISNT OUT OF THE QUESTION AND HAVE
MAINTAINED LOW POPS THERE.

THIS EVENING THE LOW LEVEL FLOW WILL GRADUALLY VEER AND SEND THE
LAKE EFFECT MORE INTO EASTERN COOK/EASTERN WILL/WESTERN LAKE IN (AND
EVEN POINTS SOUTH. BY THIS EVENING THE BOUNDARY LAYER FLOW WILL BE
WEAKENING AND THE TEMPS OUTSIDE OF THE LAKE INFLUENCED AREAS
DROPPING WHICH WOULD BOTH TEND TO FAVOR A TRANSITION TO A MORE
ORGANIZED DOMINANT SINGLE LAKE EFFECT BAND. MY BEST GUESS IS THAT
THE TIME WINDOW FOR THE HIGHEST PROBABILITY OF A DOMINANT LAKE
EFFECT BAND WITH POTENTIAL FOR HEAVY SNOW IS BETWEEN 23Z AND ABOUT
04Z. DURING THIS TIME PERIOD THE INSTABILITY (WHILE LESS THAN
EARLIER IN THE DAY) WILL STILL BE STRONG WITH INVERSION HEIGHTS
AROUND 10K FT AND LAKE-850 DELTA T VALUES >20C. DOES APPEARS A
PERIOD OF HEAVY SNOW COULD OCCUR IN EASTERN/SOUTHEASTERN COOK AND
EASTERN WILL COUNTIES EARLY THIS EVENING...BUT GIVEN THE LOW
CONFIDENCE OPTED NOT TO EXPAND THE WINTER WX HEADLINES AT THIS TIME
AND INSTEAD WILL ALLOW DAY SHIFT TO MONITOR MESOSCALE TRENDS. BY
LATER THIS EVENING INTO THE OVERNIGHT HOURS THE LAKE EFFECT
PARAMETERS WILL CONTINUE TO BECOME LESS FAVORABLE AND THE INTENSITY
OF THE LAKE EFFECT PRECIP SHOULD BEGIN TO WIND DOWN LATE TONIGHT AND
EVENTUALLY END SATURDAY. HAVE EXTENDED THE HIGHER POPS LATER IN TIME
AS LAKE EFFECT RARELY WINDS DOWN AS QUICKLY AS MODEL PROGGED
PARAMETERS SUGGEST IT WILL. WORTH NOTING THAT BY LATE EVENING AND
THROUGH SAT MORNING THE CONVECTIVE CLOUD TOP TEMPS DROP BELOW -12C
MEANING THE LIKELIHOOD OF CLOUDS CONTAINING ICE NUCLEI FOR SNOW WILL
BE LOW...SO DESPITE LOWER TEMPS IN THE BOUNDARY LAYER HAVE
TRANSITIONED P-TYPE BACK TO RAIN OR SNOW LATE TONIGHT AND SAT
MORNING.

FINALLY...HIGH WINDS WILL BE THE OTHER CONCERN TODAY. PLAN TO
MAINTAIN WIND ADVISORY AS IS THOUGH CONFIDENCE IN INLAND LOCATIONS
REACHING ADVISORY CRITERIA IS NOT THAT HIGH...BUT WITH GUSTS TO AT
LEAST 40 MPH A GOOD BET NOTHING WOULD BE GAINED FROM MAKING ANY
CHANGES TO THE HEADLINES. THE STORM WARNING FOR THE LAKE LOOKS
LIKELY TO VERIFY WITH 40 MPH SUSTAINED AND POSSIBLY GUSTS TO 58 MPH
LIKELY ALONG THE LAKE FRONT TODAY AND REALLY NOT COMFORTABLE NOT
HAVING A WARNING WITH THE POTENTIAL FOR DAMAGING WINDS ALONG THE
LAKE...SO AM GOING TO UPGRADE TO A HIGH WIND WARNING FOR LAKE SHORE
AREAS.

HEADLINES ARE AN ABSOLUTE MESS AND HEADACHE. WINTER WX ADVISORY
COVERS WIND AND SNOW...BUT IN ORDER TO GO WITH WARNING FOR WIND
ALONG THE LAKE FRONT IN INDIANA WOULD NEED TO UPGRADE TO A WINTER
STORM WARNING WHICH REALLY DOESNT SEEM TO BE THE BEST PRODUCT. AFTER
MUCH HEMMING AND HAWING AND INTERNAL COORDINATION HAVE OPTED TO
CHANGE THE WINTER WX ADV TO A LAKE EFFECT SNOW ADVISORY AND ISSUE A
WIND ADVISORY FOR JASPER AND NEWTON AND A HIGH WIND WARNING FOR LAKE
SHORE AREAS OF COOK...PORTER...AND LAKE IN. MAY NEED TO REPLACE THE
HIGH WIND WARNING WITH A WIND ADVISORY BY EARLY EVENING FOR

IZZI

&&

.LONG TERM...
325 AM CDT

SATURDAY NIGHT THROUGH THURSDAY...

MUCH...MUCH QUIETER SUNDAY AND MONDAY WITH MODERATING TEMPS. SLOW
MOVING FRONT COULD BRING A SOMEWHAT PROLONGED PERIOD OF RAIN/SHOWERS
MONDAY NIGHT THOUGH TUESDAY NIGHT. GENERALLY SEASONABLE TEMPS
EXPECTED THROUGH THE EXTENDED.

IZZI

&&

.AVIATION...

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

* 1-2 HR PERIOD OF -SHSN TIL ABOUT 14Z. BRIEF IFR VSBY AROUND 1SM.

* NORTHWEST WINDS SHIFTING NORTH TOWARD 15Z WITH GUSTS INCREASING
  TO 35-40 KT. GUST SPEEDS MAY BE VERY ERRATIC AND NOT CLEAR ON
  HOW FREQUENT 40 KT GUSTS COULD BE.

* PERIODIC MVFR CIGS THROUGH THE MORNING.

* LAKE EFFECT SNOW SHOWERS COULD AFFECT MDW FROM EARLY EVENING
  ONWARD.

MDB

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

NORTHWEST WINDS HAVE BEEN STEADILY INCREASING EARLY THIS MORNING
AS STRONG HIGH PRESSURE APPROACHES FROM THE NORTHWEST. ONE UPPER
WAVE AND ASSOCIATED -SHRA IS DEPARTING WHILE ANOTHER IS APPROACHING
FROM THE NORTH. A PUSH OF COLDER AIR WITH THE NEXT WAVE IS
RESULTING IN A BAND OF SNOW SHOWERS WHICH HAS BEEN REDUCING VSBY
TO AROUND A MILE AT TIMES...AT LEAST BRIEFLY. EXPECT A 1-2 HR
WINDOW OF -SHSN AT THE TERMINALS OVER THE NEXT 2-3 HRS. VARIABLE
MVFR-VFR CIGS WILL CONTINUE THROUGH MUCH OF THE MORNING BEFORE
STEADIER VFR IS EXPECTED ACROSS THE ILLINOIS TERMINALS WITH
SCATTERING OF CLOUDS WEST.

WINDS WILL TURN TO THE NORTH WITH THE PASSAGE OF THE UPPER WAVE
THIS MORNING AND EXPECT TO SEE A SURGE IN GUSTS AT THAT TIME. 35
TO 40 KT GUSTS ARE EXPECTED BUT AM NOT HIGHLY CONFIDENT IN HOW
FREQUENTLY 40 KT MAY BE REACHED. IT APPEARS THAT MID MORNING MAY
BE ONE POTENTIALLY PRIME PERIOD BEHIND THE UPPER WAVE/PRECIP WITH
THE NEXT POTENTIALLY FAVORED TIME BEING MID AFTERNOON IF SKIES CAN
SCATTER. IT MAY BE THAT AN OCCASIONAL 40 KT GUST OCCURS AT ANY
POINT THROUGH THE DAY. WINDS WILL EASE THIS EVENING.

LAKE EFFECT PRECIPITATION IS EXPECTED TO DEVELOP MID TO LATE
MORNING AND FOCUS ACROSS NORTHWEST INDIANA WITH GYY POSSIBLY BEING
ON THE WESTERN FRINGE INITIALLY BUT LIKELY GETTING INTO THE PRIME
BANDING INTO THE AFTERNOON. GIVEN THEIR PROXIMITY TO THE FAIRLY
WARM LAKE A RAIN SNOW MIX IS FAVORED TURNING TO ALL SNOW IF VERY
INTENSE BANDING CAN OCCUR. THUNDER IS ALSO POSSIBLE AND WOULD
ENHANCE THE ALL SNOW POTENTIAL. AS A RESULT IFR VSBY WILL LIKELY
OCCUR AT TIMES BUT THERE ARE FACTORS THAT MAY LIMIT THE
ORGANIZATION OF THE PRECIP. WINDS WILL LIKELY GUST 40-45 KT WITH
50 NOT OUT OF THE QUESTION TOWARD MIDDAY. LAKE EFFECT PRECIP WILL
LIKELY TURN TO ALL SNOW THIS EVENING AND SHIFT WESTWARD TOWARD THE
IL/IN STATE LINE AND POSSIBLY BEGIN TO IMPACT MDW WITH LIGHT
ACCUMULATIONS POSSIBLE...MAINLY ON THE GRASS. SEVERAL HOURS OF
SNOW MAY OCCUR AT OR NEAR MDW. ADJUSTMENTS TO THE FORECAST DETAILS
THIS EVENING AT MDW/GYY AND EVEN ORD ARE LIKELY.

MDB

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

* HIGH CONFIDENCE IN SNOW SHOWERS THIS MORNING...HIGH CONFIDENCE
  IN DURATION...MEDIUM-HIGH CONFIDENCE IN BRIEF IFR VSBY
  OCCURRING.

* HIGH CONFIDENCE IN NORTHWEST WINDS TURNING NORTH AND IN GUSTS
  REACHING 35-37 KT...MEDIUM CONFIDENCE THAT SOME 40 KT GUSTS WILL
  OCCUR BUT LOW CONFIDENCE IN FREQUENCY AND BEST TIMING.

* MEDIUM-HIGH CONFIDENCE IN PERIODIC MVFR CIGS THROUGH THE
  MORNING.

* LOW CONFIDENCE IN LAKE EFFECT SNOW SHOWER POTENTIAL THIS EVENING
  AT ORD...MEDIUM CONFIDENCE AT MDW.

MDB

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

* SATURDAY NIGHT...DRY VFR. LIGHT/VARIABLE WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS 10-15 KT.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.
* TUESDAY...SHRA/MVFR LIKELY. SOUTHWEST WINDS.
* WEDNESDAY...DRY/VFR. SOUTHWEST WINDS.
* THURSDAY...DRY/VFR. WEST WINDS.

MDB

&&

.MARINE...
256 AM CDT

A MAJOR WIND EVENT CONTINUES TO TAKE SHAPE FOR LAKE MICHIGAN EARLY
THIS MORNING. FAIRLY BROAD LOW PRESSURE OVER LAKE HURON WILL TRACK
SOUTHEAST TO LAKE ERIE BY MIDDAY THEN CONTINUE TO THE CAROLINA COAST
TONIGHT AND MERGE WITH DEVELOPING LOW PRESSURE. VERY STRONG HIGH
PRESSURE STRETCHED ACROSS THE NORTHERN PLAINS INTO CENTRAL CANADA IS
THE KEY TO THE RAPIDLY INCREASING WINDS THAT ARE NOW REACHING THE
NORTHERN PORTION OF THE LAKE. THE PRESSURE GRADIENT WILL QUICKLY
INCREASE ACROSS THE LAKE INTO MID MORNING AS A COLD FRONT SWEEPS
ACROSS ALLOWING MUCH COLDER AIR TO SPREAD DOWN THE LAKE. NORTH WINDS
WILL LIKELY INCREASE TO STORM FORCE AROUND 50 KT FOR MOST OF THE
LAKE WITH THE FAR NORTHERN SECTION HOLDING AT GALES...THOUGH A FEW
50 KT GUSTS COULD OCCUR THIS MORNING. MAY SEE SOME 55 KT GUSTS AT
TIMES ACROSS THE SOUTH HALF OF THE LAKE...ESPECIALLY LATE THIS
MORNING INTO MIDDAY. THIS RAPID INCREASE IN WINDS AND STRONG
MIXING OVER THE LAKE WILL ALLOW FOR A RAPID BUILDING OF WAVES
THROUGH THE MORNING TO AROUND 20 FEET BY EARLY/MID AFTERNOON
ACROSS THE CENTRAL AND SOUTHERN PART OF THE LAKE. WILL CONTINUE
WITH 18-23 FT PREVAILING WAVES IN THE FORECAST FOR THESE AREAS.
WINDS WILL BEGIN TO EASE THIS EVENING AND TREND A BIT
NORTHEASTERLY. SHOULD SEE WINDS FALL BELOW GALE FORCE OVERNIGHT
BUT WINDS WILL BE SLOW TO DIMINISH SIGNIFICANTLY THROUGH MIDDAY
SATURDAY SO WAVES WILL LIKELY BE SLOW TO FALL AS WELL. WILL LEAVE
EXISTING GALE AND STORM WARNINGS AS-IS.

THE HIGH WILL PASS OVER THE LAKE SATURDAY EVENING THROUGH SUNDAY
KEEPING WINDS LIGHT BUT SOUTH TO SOUTHWEST WINDS WILL INCREASE
THROUGH THE DAY SUNDAY AND MAY PUSH 30 KT LATE SUNDAY
AFTERNOON/EVENING AS LOW PRESSURE TRACKS NORTHEAST ACROSS THE
NORTHERN PLAINS. SOUTHWEST WINDS WILL REMAIN STRONG THROUGH MONDAY
NIGHT THEN LET UP NORTH AS LOW PRESSURE TRACKS FROM THE SOUTHERN
PLAINS ACROSS NORTHERN LAKE MICHIGAN...WHILE THE SOUTH SEES BREEZY
CONDITIONS CONTINUE. WINDS TURN WESTERLY LATER TUESDAY AND
DIMINISH AS HIGH PRESSURE RIDGING EXTENDS ACROSS THE AREA.

MDB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HIGH WIND WARNING...ILZ014...10 AM FRIDAY TO 6 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022-ILZ023-
     ILZ033 UNTIL 7 PM FRIDAY.

IN...HIGH WIND WARNING...INZ001-INZ002...10 AM FRIDAY TO 6 PM FRIDAY.

     LAKE EFFECT SNOW ADVISORY...INZ001-INZ002-INZ010-INZ011...10 AM
     FRIDAY TO 10 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WIND ADVISORY...INZ010-INZ011-INZ019 UNTIL 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 PM FRIDAY TO
     4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563 UNTIL 10 PM FRIDAY.

     GALE WARNING...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 4 AM SATURDAY.

&&

$$

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000
FXUS63 KLOT 310922
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
422 AM CDT FRI OCT 31 2014

.SHORT TERM...
326 AM CDT

THROUGH SATURDAY...

ACTIVE WEATHER ON TAP THE NEXT 24 HOURS AS COMPACT AND DEEP UPPER
LOW DIVES SOUTH ACROSS THE REGION DRAGGING UNSEASONABLY COLD
AIR...BOTH AT THE SURFACE AND ALOFT...INTO THE REGION TODAY INTO
TONIGHT. EARLY THIS MORNING SURFACE ANALYSIS SHOWS A RATHER DIFFUSE
COLD FRONT MOVING ACROSS THE REGION WITH STRONG COLD ADVECTION
RESULTING IN A HEALTHY TEMP DROP PRIOR TO SUNRISE OVER NORTHERN CWA
AND SHORTLY AFTERWARD SOUTHEAST. STRONG NNW WINDS WILL ALSO ARRIVE
WITH THE COLD AIR AND CONTINUE INTO THIS EVENING RESULTING IN
TEMPERATURES LARGELY REMAINING FAIRLY STEADY THROUGH THE AFTERNOON.

COMPACT VORT AND REALLY THE HEART OF THE UPPER LOW SHOWS UP NICELY
OVER NORTHERN WISCONSIN EARLY THIS MORNING AND IS DIVING SSE TOWARD
THE AREA. THE COMBINATION OF ASCENT WITH THIS FEATURE AND STEEP
LAPSE RATES ARE RESULTING IN SCATTERED BUT FAIRLY VIGOROUS SNOW
SHOWERS OVER NORTHERN AND CENTRAL WISCONSIN AND WOULD FULLY
ANTICIPATE THESE TO MAINTAIN THEMSELVES AND MOVE ACROSS MAINLY THE
EASTERN CWA THIS MORNING. TEMPS WILL PROBABLY BE TOO WARM FOR MUCH
IF ANY ACCUMULATION...BUT SOME OF THE SNOW SHOWERS COULD BE BRIEFLY
VIGOROUS AND KNOCK VSBY DOWN TO BELOW 1SM. AS THE VORT CONTINUE
SOUTHEAST LOOK FOR THE NON-LAKE DRIVEN PRECIP TO END BY MID MORNING
NORTHERN CWA AND LATE MORNING SOUTHEAST CWA.

THE VORT WILL HERALD THE ARRIVAL OF THE COLDEST AIR ALOFT AND
RESULTANT STRONGEST INSTABILITY OVER THE LAKE AS H5 TEMPS DROP TO
-33C AND H7 TEMPS BELOW -15C. THERMODYNAMIC PROFILES OVER THE LAKE
BEHIND THIS VORT BECOME EXPLOSIVELY UNSTABLE THIS MORNING REMAIN SO
THROUGH THE DAY. LAKE EFFECT SHOULD GET GOING IN ERNEST BEHIND THIS
VORT AND CONTINUE TO SOME DEGREE INTO SATURDAY MORNING. FORECAST
LAKE INDUCED EQUILIBRIUM LEVELS TODAY APPROACH 20K FT...NEAR THE
-30C LEVEL...WHICH IS MORE THAN COLD ENOUGH TO SUPPORT LIGHTNING
GIVEN THE HIGH LIKELIHOOD OF MIXED PHASE HYDROMETEORS (SUPERCOOLED
DROPLETS AND ICE) IN THE CLOUDS WITHIN STRONG UPDRAFTS. NEAR SURFACE
TEMPS OVER THE LAKE AND WITHIN A FEW MILES OF THE LAKE SHORE MAY BE
WARM ENOUGH TO SUPPORT P-TYPE FLUCTUATING BETWEEN RAIN...RAIN/SNOW
MIX...AND ALL SNOW. LAKE EFFECT PRECIP FARTHER INLAND STANDS A MUCH
BETTER CHANCE OF REMAINING ALL OR MOSTLY SNOW.

ONE OF THE BIGGER UNCERTAINTIES FOR TODAY IS HOW ORGANIZED THE LAKE
EFFECT WILL BECOME AND WHETHER IT WILL BE MULTIPLE BANDS OR A SINGLE
INTENSE BAND. GIVEN THE VERY STRONG BOUNDARY LAYER WINDS AND LESS
THAN IDEAL TIME OF DAY AM CONCERNED THAT THE LAKE EFFECT PRECIP
COULD BE SOMEWHAT UNORGANIZED/SCATTERED IN NATURE WITH MULTIPLE
BANDS DURING THE DAY WHICH WILL BE THE TIME OF STRONG TO EXTREME
INSTABILITY. IF A MORE ORGANIZED DOMINANT SINGLE BAND DOES
FORM...THE STRONG FLOW AND INSTABILITY WELL INLAND WOULD SUPPORT
INTENSE PRECIP RATES MAKING IT WELL INLAND THIS AFTERNOON WHERE
P-TYPE WOULD LIKELY BE MOSTLY SNOW...POSSIBLY MODERATE TO HEAVY
SNOW. IF SNOW FALLS HEAVY ENOUGH THEN THE WARM GROUND TEMPS WOULD
BECOME MORE OF A MOOT POINT WITH RAPID ACCUMULATIONS OF HEAVY/WET
SNOW...ESPECIALLY ON GRASSY SURFACES WHERE ISOLATED LOCATIONS COULD
SEE A QUICK SEVERAL INCHES OF SNOW. THE MOST LIKELY SCENARIO WOULD
APPEAR TO BE SOMEWHAT LESS ORGANIZED BANDS OF SNOW SHOWERS RESULTING
IN ONLY MINOR ACCUMS ON GRASSY SURFACES IN SPOTS TODAY. THE WIND
WILL BE WHIPPING THE SNOW AROUND REGARDLESS SO UNDERNEATH ANY LAKE
EFFECT SNOW CONDITIONS WILL BE PRETTY MISERABLE EVEN THOUGH IT IS
UNLIKELY TO ACCUMULATE ON ROADS/SIDEWALKS TODAY. LAKE AND PORTER
COUNTY LOOK TO BE GROUND ZERO FOR THE LAKE EFFECT TODAY WITH THE
PRECIP LIKELY MAKING IT WELL INLAND TO JASPER AND NEWTON COUNTIES.
SOME HIGH RES GUIDANCE DOES CLIP SE COOK AND EASTERN WILL WITH LAKE
EFFECT PRECIP TODAY WHICH ISNT OUT OF THE QUESTION AND HAVE
MAINTAINED LOW POPS THERE.

THIS EVENING THE LOW LEVEL FLOW WILL GRADUALLY VEER AND SEND THE
LAKE EFFECT MORE INTO EASTERN COOK/EASTERN WILL/WESTERN LAKE IN (AND
EVEN POINTS SOUTH. BY THIS EVENING THE BOUNDARY LAYER FLOW WILL BE
WEAKENING AND THE TEMPS OUTSIDE OF THE LAKE INFLUENCED AREAS
DROPPING WHICH WOULD BOTH TEND TO FAVOR A TRANSITION TO A MORE
ORGANIZED DOMINANT SINGLE LAKE EFFECT BAND. MY BEST GUESS IS THAT
THE TIME WINDOW FOR THE HIGHEST PROBABILITY OF A DOMINANT LAKE
EFFECT BAND WITH POTENTIAL FOR HEAVY SNOW IS BETWEEN 23Z AND ABOUT
04Z. DURING THIS TIME PERIOD THE INSTABILITY (WHILE LESS THAN
EARLIER IN THE DAY) WILL STILL BE STRONG WITH INVERSION HEIGHTS
AROUND 10K FT AND LAKE-850 DELTA T VALUES >20C. DOES APPEARS A
PERIOD OF HEAVY SNOW COULD OCCUR IN EASTERN/SOUTHEASTERN COOK AND
EASTERN WILL COUNTIES EARLY THIS EVENING...BUT GIVEN THE LOW
CONFIDENCE OPTED NOT TO EXPAND THE WINTER WX HEADLINES AT THIS TIME
AND INSTEAD WILL ALLOW DAY SHIFT TO MONITOR MESOSCALE TRENDS. BY
LATER THIS EVENING INTO THE OVERNIGHT HOURS THE LAKE EFFECT
PARAMETERS WILL CONTINUE TO BECOME LESS FAVORABLE AND THE INTENSITY
OF THE LAKE EFFECT PRECIP SHOULD BEGIN TO WIND DOWN LATE TONIGHT AND
EVENTUALLY END SATURDAY. HAVE EXTENDED THE HIGHER POPS LATER IN TIME
AS LAKE EFFECT RARELY WINDS DOWN AS QUICKLY AS MODEL PROGGED
PARAMETERS SUGGEST IT WILL. WORTH NOTING THAT BY LATE EVENING AND
THROUGH SAT MORNING THE CONVECTIVE CLOUD TOP TEMPS DROP BELOW -12C
MEANING THE LIKELIHOOD OF CLOUDS CONTAINING ICE NUCLEI FOR SNOW WILL
BE LOW...SO DESPITE LOWER TEMPS IN THE BOUNDARY LAYER HAVE
TRANSITIONED P-TYPE BACK TO RAIN OR SNOW LATE TONIGHT AND SAT
MORNING.

FINALLY...HIGH WINDS WILL BE THE OTHER CONCERN TODAY. PLAN TO
MAINTAIN WIND ADVISORY AS IS THOUGH CONFIDENCE IN INLAND LOCATIONS
REACHING ADVISORY CRITERIA IS NOT THAT HIGH...BUT WITH GUSTS TO AT
LEAST 40 MPH A GOOD BET NOTHING WOULD BE GAINED FROM MAKING ANY
CHANGES TO THE HEADLINES. THE STORM WARNING FOR THE LAKE LOOKS
LIKELY TO VERIFY WITH 40 MPH SUSTAINED AND POSSIBLY GUSTS TO 58 MPH
LIKELY ALONG THE LAKE FRONT TODAY AND REALLY NOT COMFORTABLE NOT
HAVING A WARNING WITH THE POTENTIAL FOR DAMAGING WINDS ALONG THE
LAKE...SO AM GOING TO UPGRADE TO A HIGH WIND WARNING FOR LAKE SHORE
AREAS.

HEADLINES ARE AN ABSOLUTE MESS AND HEADACHE. WINTER WX ADVISORY
COVERS WIND AND SNOW...BUT IN ORDER TO GO WITH WARNING FOR WIND
ALONG THE LAKE FRONT IN INDIANA WOULD NEED TO UPGRADE TO A WINTER
STORM WARNING WHICH REALLY DOESNT SEEM TO BE THE BEST PRODUCT. AFTER
MUCH HEMMING AND HAWING AND INTERNAL COORDINATION HAVE OPTED TO
CHANGE THE WINTER WX ADV TO A LAKE EFFECT SNOW ADVISORY AND ISSUE A
WIND ADVISORY FOR JASPER AND NEWTON AND A HIGH WIND WARNING FOR LAKE
SHORE AREAS OF COOK...PORTER...AND LAKE IN. MAY NEED TO REPLACE THE
HIGH WIND WARNING WITH A WIND ADVISORY BY EARLY EVENING FOR

IZZI

&&

.LONG TERM...
325 AM CDT

SATURDAY NIGHT THROUGH THURSDAY...

MUCH...MUCH QUIETER SUNDAY AND MONDAY WITH MODERATING TEMPS. SLOW
MOVING FRONT COULD BRING A SOMEWHAT PROLONGED PERIOD OF RAIN/SHOWERS
MONDAY NIGHT THOUGH TUESDAY NIGHT. GENERALLY SEASONABLE TEMPS
EXPECTED THROUGH THE EXTENDED.

IZZI

&&

.AVIATION...

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

* FEW HOUR PERIOD OF SNOW SHOWERS AROUND/AFTER DAYBREAK. BRIEF IFR
  VSBY POSSIBLE.

* NORTHWEST WINDS SHIFTING NORTH AFTER DAYBREAK WITH GUSTS
  INCREASING TO 35-40 KT. NOT CLEAR ON FREQUENCY OF 40 KT GUSTS.

* PERIODIC MVFR CIGS THROUGH THE MORNING.

* LAKE EFFECT SNOW SHOWERS COULD AFFECT MDW FROM EARLY EVENING
  ONWARD.

MDB

//DISCUSSION...UPDATED 09Z...

WINDS HAVE SHIFTED NORTHWEST WITH GUST FREQUENCY/INTENSITY PICKING
UP. LIGHT RAIN SHOWERS CONTINUE TO MOVE SOUTHEAST ACROSS THE
TERMINALS WITH ONE UPPER WAVE. ANOTHER WAVE IS MOVING SOUTHWARD
ACROSS CENTRAL WISCONSIN AND GENERATING BANDS OF SNOW AS COLDER
AIR SPILLS IN. HAVE HIT SNOW SHOWER MENTION A LITTLE HARDER FOR A
FEW HOURS BETWEEN 12 AND 15Z OR SO. BRIEF IFR VSBY IS POSSIBLE
WITH A FEW SITES HAVING REPORTED ANYWHERE FROM 1/2 TO 3 SM
UPSTREAM. SUSPECT THAT MANY SITES HAVE BEEN TO 2-3SM OR LOWER BUT
DURATION WAS TOO BRIEF TO MAKE IT INTO THE TRANSMITTED OB. NOT
EXPECTING ANY ACCUMULATION WITH THESE SNOW SHOWERS BUT VSBY COULD
BE BRIEFLY REDUCED LOWER THAN WHAT THE TAFS CURRENTLY SHOW. GUST
MAGNITUDE/FREQUENCY REMAIN A CHALLENGE ESPECIALLY AT ORD/MDW GIVEN
POTENTIAL FOR CLOUD COVER TO LIMIT PEAK GUSTS.

FROM 06Z...

NUMEROUS FORECAST CONCERNS CONTINUE WITH LOW PRESSURE OVER LAKE
HURON TRACKING SOUTHEAST AND VERY STRONG HIGH PRESSURE OVER THE
NORTHERN PLAINS TRAILING IT. WINDS ARE BEGINNING TO TURN NORTHWEST
WITH A COLD FRONT ENTERING NORTHWEST ILLINOIS AT 06Z AND MOVING
SOUTHEAST. WINDS WILL INCREASE IN SPEED OVER THE NEXT SEVERAL
HOURS. A SERIES OF UPPER DISTURBANCES WILL CROSS THE AREA THROUGH
THE MORNING WITH THE FIRST NOW BRINGING RAIN SHOWERS TO THE
TERMINALS. THE NEXT WILL ARRIVE OVERNIGHT BRINGING INTERMITTENT
SHOWERS WITH A BETTER DEFINED WAVE CROSSING THE AREA AROUND/AFTER
DAYBREAK BRINGING SNOW SHOWERS AS MUCH COLDER AIR ARRIVES. AREAS
OF NORTHERN WISCONSIN ARE SEEING IFR SNOW THIS HOUR BUT THESE
HEAVIER BURSTS ARE EXPECTED TO TRACK TO THE EAST OF THE TERMINALS.
STILL CANNOT RULE OUT A BRIEF HEAVIER BURST OF NON-ACCUMULATING
SNOW AT ORD/MDW/GYY BUT WILL CONTINUE WITH MINIMAL VSBY
RESTRICTION. OTHERWISE EXPECT INTERMITTENT MVFR CIGS TO DEVELOP
WITH QUITE A BIT OF VARIABILITY BASED ON UPSTREAM CONDITIONS.

WINDS FURTHER INCREASE BEHIND THIS SNOW PRODUCING WAVE WITH GUSTS
OF 35-40 KT EXPECTED. IT IS UNCLEAR HOW FREQUENT THAT 40 KT GUSTS
WILL OCCUR BUT AM FAIRLY CONFIDENT THAT THEY WILL. AM THINKING
THAT THERE MAY BE TWO SEPARATE WINDOWS WHERE 40 KT WILL BE MOST
LIKELY...ONE BEING MID/LATE MORNING BEHIND THE SNOW PRODUCING WAVE
AND THE OTHER BEING MID AFTERNOON WHEN SKIES ARE MOST LIKELY TO
SCATTER. WITH OVERALL CONFIDENCE IN 40 KT FREQUENCY ON THE LOW
SIDE WILL CONTINUE WITH PREVIOUS DURATION FOR NOW BUT WILL ATTEMPT
TO REFINE WITH THE NEXT UPDATE IF POSSIBLE.

THE NEXT ISSUE WILL BE LAKE EFFECT PRECIPITATION. GYY LOOKS TO BE
IN LINE FOR LAKE EFFECT RAIN/SNOW AND POSSIBLY PERIODS OF ALL SNOW
FROM LATE MORNING INTO THE EVENING. THUNDER IS ALSO POSSIBLE AS
CONDITIONS BECOME QUITE UNSTABLE OVER THE LAKE. MAY NEED TO
INDICATE SUB 1SM VSBY IN MODERATE/HEAVY PRECIPITATION AS DETAILS
BECOME MORE CLEAR. GYY WILL ALSO LIKELY SEE THE STRONGEST WINDS
GIVEN THEIR PROXIMITY TO THE LAKE AND 45+ KT WILL BE POSSIBLE.

WINDS GRADUALLY EASE EARLY THIS EVENING AND LAKE EFFECT MAY BEGIN
TO TRANSITION WESTWARD INTO THE EARLY OVERNIGHT SO MDW AND
POSSIBLY ORD COULD BE IN LINE FOR SOME SNOW SHOWERS BUT CONDITIONS
WILL BECOME LESS FAVORABLE WITH TIME INTO SATURDAY MORNING. WILL
CONTINUE WITH SNOW SHOWER MENTION AT MDW THIS EVENING BUT LEAVE
ORD DRY FOR NOW.

MDB

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

* HIGH CONFIDENCE IN SOME SNOW SHOWERS THIS MORNING...MEDIUM
  CONFIDENCE IN DURATION...LOW CONFIDENCE IN IF BRIEF IFR VSBY
  WILL OCCUR.

* HIGH CONFIDENCE IN NORTHWEST WINDS TURNING NORTH AND IN GUSTS
  REACHING 35-37 KT...MEDIUM CONFIDENCE THAT SOME 40 KT GUSTS WILL
  OCCUR BUT LOW CONFIDENCE IN FREQUENCY AND BEST TIMING.

* MEDIUM-HIGH CONFIDENCE IN PERIODIC MVFR CIGS THROUGH THE
  MORNING.

* LOW CONFIDENCE IN LAKE EFFECT SNOW SHOWER POTENTIAL THIS EVENING
  AT ORD...MEDIUM CONFIDENCE AT MDW.

MDB

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

* SATURDAY...DRY/VFR. NORTHEAST WINDS 10-15 KT.
* SUNDAY...DRY/VFR. SOUTH WINDS 10-15 KT.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.
* TUESDAY...SHRA/MVFR LIKELY. SOUTHWEST WINDS.
* WEDNESDAY...DRY/VFR. SOUTHWEST WINDS.

&&

.MARINE...
256 AM CDT

A MAJOR WIND EVENT CONTINUES TO TAKE SHAPE FOR LAKE MICHIGAN EARLY
THIS MORNING. FAIRLY BROAD LOW PRESSURE OVER LAKE HURON WILL TRACK
SOUTHEAST TO LAKE ERIE BY MIDDAY THEN CONTINUE TO THE CAROLINA COAST
TONIGHT AND MERGE WITH DEVELOPING LOW PRESSURE. VERY STRONG HIGH
PRESSURE STRETCHED ACROSS THE NORTHERN PLAINS INTO CENTRAL CANADA IS
THE KEY TO THE RAPIDLY INCREASING WINDS THAT ARE NOW REACHING THE
NORTHERN PORTION OF THE LAKE. THE PRESSURE GRADIENT WILL QUICKLY
INCREASE ACROSS THE LAKE INTO MID MORNING AS A COLD FRONT SWEEPS
ACROSS ALLOWING MUCH COLDER AIR TO SPREAD DOWN THE LAKE. NORTH WINDS
WILL LIKELY INCREASE TO STORM FORCE AROUND 50 KT FOR MOST OF THE
LAKE WITH THE FAR NORTHERN SECTION HOLDING AT GALES...THOUGH A FEW
50 KT GUSTS COULD OCCUR THIS MORNING. MAY SEE SOME 55 KT GUSTS AT
TIMES ACROSS THE SOUTH HALF OF THE LAKE...ESPECIALLY LATE THIS
MORNING INTO MIDDAY. THIS RAPID INCREASE IN WINDS AND STRONG
MIXING OVER THE LAKE WILL ALLOW FOR A RAPID BUILDING OF WAVES
THROUGH THE MORNING TO AROUND 20 FEET BY EARLY/MID AFTERNOON
ACROSS THE CENTRAL AND SOUTHERN PART OF THE LAKE. WILL CONTINUE
WITH 18-23 FT PREVAILING WAVES IN THE FORECAST FOR THESE AREAS.
WINDS WILL BEGIN TO EASE THIS EVENING AND TREND A BIT
NORTHEASTERLY. SHOULD SEE WINDS FALL BELOW GALE FORCE OVERNIGHT
BUT WINDS WILL BE SLOW TO DIMINISH SIGNIFICANTLY THROUGH MIDDAY
SATURDAY SO WAVES WILL LIKELY BE SLOW TO FALL AS WELL. WILL LEAVE
EXISTING GALE AND STORM WARNINGS AS-IS.

THE HIGH WILL PASS OVER THE LAKE SATURDAY EVENING THROUGH SUNDAY
KEEPING WINDS LIGHT BUT SOUTH TO SOUTHWEST WINDS WILL INCREASE
THROUGH THE DAY SUNDAY AND MAY PUSH 30 KT LATE SUNDAY
AFTERNOON/EVENING AS LOW PRESSURE TRACKS NORTHEAST ACROSS THE
NORTHERN PLAINS. SOUTHWEST WINDS WILL REMAIN STRONG THROUGH MONDAY
NIGHT THEN LET UP NORTH AS LOW PRESSURE TRACKS FROM THE SOUTHERN
PLAINS ACROSS NORTHERN LAKE MICHIGAN...WHILE THE SOUTH SEES BREEZY
CONDITIONS CONTINUE. WINDS TURN WESTERLY LATER TUESDAY AND
DIMINISH AS HIGH PRESSURE RIDGING EXTENDS ACROSS THE AREA.

MDB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...HIGH WIND WARNING...ILZ014...10 AM FRIDAY TO 6 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022-ILZ023-
     ILZ033...8 AM FRIDAY TO 7 PM FRIDAY.

IN...HIGH WIND WARNING...INZ001-INZ002...10 AM FRIDAY TO 6 PM FRIDAY.

     LAKE EFFECT SNOW ADVISORY...INZ001-INZ002-INZ010-INZ011...10 AM
     FRIDAY TO 10 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WIND ADVISORY...INZ010-INZ011-INZ019...8 AM FRIDAY TO 7 PM
     FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 PM FRIDAY TO
     4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563 UNTIL 10 PM FRIDAY.

     GALE WARNING...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 4 AM SATURDAY.

&&

$$

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

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






000
FXUS63 KILX 310831
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
331 AM CDT Fri Oct 31 2014

.SHORT TERM...(Today)
ISSUED AT 330 AM CDT FRI OCT 31 2014

The passage of a strong cold front and upper level shortwave will
highlight the short term forecast. At 08z/3am the front had already
reached near the Illinois River Valley, with the upper wave centered
behind the front across Wisconsin. Very gusty northwest winds were
lagging behind the front by a couple of hours, so winds in our
counties will begin to increase by around sunrise, especially NW of
Lincoln. Wind gusts this afternoon will climb into the 30-40 mph
range, especially east of Peoria to Springfield. Spotty rain showers
or sprinkles were developing just ahead of the front, generally
along and east of the I-55 corridor at 3 am.

Spotty showers will continue to advance eastward with the front
today, then linger this afternoon as the upper level shortwave
affects eastern Illinois. As colder air arrives on brisk northwest
winds today, some of the light rain showers could change over to
snow showers for areas east of Champaign and north of Paris.

Highs today will likely occur this morning, as the colder air and
cloud cover prevent temperatures from rising much this afternoon.
Temps will likely become steady or slowly fall by midday in most
areas.


&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 330 AM CDT FRI OCT 31 2014

A potent Canadian shortwave will dive sse from Lake Superior and WI
across IN/KY tonight. North-northwest winds 20-30 mph with gusts
30-40 mph will diminish to 10-15 mph overnight with gusts up to 20
mph. This will advect in subfreezing temperatures of 25-30F and
bring a killing freeze to much of IL overnight until mid morning
Saturday. Will continue the freezing warning overnight until 9 am
Sat for central and southeast IL. Moisture flow off Lake MI could
bring a few snow showers near the IN border especially over
Vermilion county this evening. A taste of early winter weather for
Halloween Trick or Treaters this evening with wind chills slipping
into the low to mid 20s. Chilly highs in the mid 40s Saturday
despite a fair amount of sunshine, due to north winds 8-15 mph and
gusts 15 to 20 mph over eastern IL.

Strong Canadian high pressure of 1039 mb over ND will settle over IL
Saturday night as it slowly weakens with fair skies and light winds.
This will bring another hard freeze overnight Saturday night and
early Sunday morning with lows in the middle to upper 20s, and
coldest east of I-57. Mostly sunny skies Sunday but still chilly
highs in the upper 40s to around 50F.

More unsettled weather pattern takes shape Monday-Wednesday as IL
gets in a southwesterly upper level flow with upper level ridge
shifting east of IL and strong upper level trof digging into the
southern Rockies. A frontal boundary will set up from the southern
Plains ne into the Ohio river valley Monday night through Wed and
bring increasing chances of showers. Cold front to move se across
central IL Tue when best chances of showers and isolated
thunderstorms will be. Have 20-30% chance of showers by Monday
afternoon west of I-55 as clouds increasing from the west during the
day. Then likely chances of showers develop during Monday night into
Tue and highest pops shift into southeast IL during Tue night and
Wed. Milder highs in the upper 50s and lower 60s Monday and 55-60F
Tue and Wed. Isolated thunderstorms may also occur Monday night and
Tue south of I-72. Slight chance of showers in southeast IL Wed
evening, otherwise drier weather is expected Wed night thru Friday
as dry west northwesterly flow trails the system with seasonable
highs still in the mid to upper 50s and near 60F in southeast IL.


&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 1105 PM CDT THU OCT 30 2014

VFR conditions will give way to a brief period of MVFR cigs in the
08z-12z time frame as a strong cold front tracks across the area.
Once the front shifts thru the area, strong northerly winds are
expected thru much of the day Friday with sustained winds of 20 to
30 kts with a few gusts around 35 kts at times. With the fropa, we
may see some scattered rain showers with the cigs lowering to
MVFR and a low probability for a brief period of IFR cigs with
any bands of rain that persist. Satellite data indicating cigs
around 2500 to 3500 feet north of the cold front over parts of
northern Iowa into central Wisconsin. Latest HRRR forecast indicates
the stratocumulus should begin to decrease in coverage and affect
mainly areas east of I55 by afternoon as subsidence develops in the
wake of the upper level shortwave. Surface winds will gradually
diminish, especially the gusts, towards evening with sustained winds
of 10 kts or less after 02z.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING from Midnight tonight to 9 AM CDT Saturday FOR
ILZ027>031-036>038-040>057-061>063-066>068-071>073.

&&

$$

SHORT TERM...Shimon
LONG TERM...07
AVIATION...Smith







000
FXUS63 KLOT 310826
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
326 AM CDT FRI OCT 31 2014

.SHORT TERM...
326 AM CDT

THROUGH SATURDAY...

ACTIVE WEATHER ON TAP THE NEXT 24 HOURS AS COMPACT AND DEEP UPPER
LOW DIVES SOUTH ACROSS THE REGION DRAGGING UNSEASONABLY COLD
AIR...BOTH AT THE SURFACE AND ALOFT...INTO THE REGION TODAY INTO
TONIGHT. EARLY THIS MORNING SURFACE ANALYSIS SHOWS A RATHER DIFFUSE
COLD FRONT MOVING ACROSS THE REGION WITH STRONG COLD ADVECTION
RESULTING IN A HEALTHY TEMP DROP PRIOR TO SUNRISE OVER NORTHERN CWA
AND SHORTLY AFTERWARD SOUTHEAST. STRONG NNW WINDS WILL ALSO ARRIVE
WITH THE COLD AIR AND CONTINUE INTO THIS EVENING RESULTING IN
TEMPERATURES LARGELY REMAINING FAIRLY STEADY THROUGH THE AFTERNOON.

COMPACT VORT AND REALLY THE HEART OF THE UPPER LOW SHOWS UP NICELY
OVER NORTHERN WISCONSIN EARLY THIS MORNING AND IS DIVING SSE TOWARD
THE AREA. THE COMBINATION OF ASCENT WITH THIS FEATURE AND STEEP
LAPSE RATES ARE RESULTING IN SCATTERED BUT FAIRLY VIGOROUS SNOW
SHOWERS OVER NORTHERN AND CENTRAL WISCONSIN AND WOULD FULLY
ANTICIPATE THESE TO MAINTAIN THEMSELVES AND MOVE ACROSS MAINLY THE
EASTERN CWA THIS MORNING. TEMPS WILL PROBABLY BE TOO WARM FOR MUCH
IF ANY ACCUMULATION...BUT SOME OF THE SNOW SHOWERS COULD BE BRIEFLY
VIGOROUS AND KNOCK VSBY DOWN TO BELOW 1SM. AS THE VORT CONTINUE
SOUTHEAST LOOK FOR THE NON-LAKE DRIVEN PRECIP TO END BY MID MORNING
NORTHERN CWA AND LATE MORNING SOUTHEAST CWA.

THE VORT WILL HERALD THE ARRIVAL OF THE COLDEST AIR ALOFT AND
RESULTANT STRONGEST INSTABILITY OVER THE LAKE AS H5 TEMPS DROP TO
-33C AND H7 TEMPS BELOW -15C. THERMODYNAMIC PROFILES OVER THE LAKE
BEHIND THIS VORT BECOME EXPLOSIVELY UNSTABLE THIS MORNING REMAIN SO
THROUGH THE DAY. LAKE EFFECT SHOULD GET GOING IN ERNEST BEHIND THIS
VORT AND CONTINUE TO SOME DEGREE INTO SATURDAY MORNING. FORECAST
LAKE INDUCED EQUILIBRIUM LEVELS TODAY APPROACH 20K FT...NEAR THE
-30C LEVEL...WHICH IS MORE THAN COLD ENOUGH TO SUPPORT LIGHTNING
GIVEN THE HIGH LIKELIHOOD OF MIXED PHASE HYDROMETEORS (SUPERCOOLED
DROPLETS AND ICE) IN THE CLOUDS WITHIN STRONG UPDRAFTS. NEAR SURFACE
TEMPS OVER THE LAKE AND WITHIN A FEW MILES OF THE LAKE SHORE MAY BE
WARM ENOUGH TO SUPPORT P-TYPE FLUCTUATING BETWEEN RAIN...RAIN/SNOW
MIX...AND ALL SNOW. LAKE EFFECT PRECIP FARTHER INLAND STANDS A MUCH
BETTER CHANCE OF REMAINING ALL OR MOSTLY SNOW.

ONE OF THE BIGGER UNCERTAINTIES FOR TODAY IS HOW ORGANIZED THE LAKE
EFFECT WILL BECOME AND WHETHER IT WILL BE MULTIPLE BANDS OR A SINGLE
INTENSE BAND. GIVEN THE VERY STRONG BOUNDARY LAYER WINDS AND LESS
THAN IDEAL TIME OF DAY AM CONCERNED THAT THE LAKE EFFECT PRECIP
COULD BE SOMEWHAT UNORGANIZED/SCATTERED IN NATURE WITH MULTIPLE
BANDS DURING THE DAY WHICH WILL BE THE TIME OF STRONG TO EXTREME
INSTABILITY. IF A MORE ORGANIZED DOMINANT SINGLE BAND DOES
FORM...THE STRONG FLOW AND INSTABILITY WELL INLAND WOULD SUPPORT
INTENSE PRECIP RATES MAKING IT WELL INLAND THIS AFTERNOON WHERE
P-TYPE WOULD LIKELY BE MOSTLY SNOW...POSSIBLY MODERATE TO HEAVY
SNOW. IF SNOW FALLS HEAVY ENOUGH THEN THE WARM GROUND TEMPS WOULD
BECOME MORE OF A MOOT POINT WITH RAPID ACCUMULATIONS OF HEAVY/WET
SNOW...ESPECIALLY ON GRASSY SURFACES WHERE ISOLATED LOCATIONS COULD
SEE A QUICK SEVERAL INCHES OF SNOW. THE MOST LIKELY SCENARIO WOULD
APPEAR TO BE SOMEWHAT LESS ORGANIZED BANDS OF SNOW SHOWERS RESULTING
IN ONLY MINOR ACCUMS ON GRASSY SURFACES IN SPOTS TODAY. THE WIND
WILL BE WHIPPING THE SNOW AROUND REGARDLESS SO UNDERNEATH ANY LAKE
EFFECT SNOW CONDITIONS WILL BE PRETTY MISERABLE EVEN THOUGH IT IS
UNLIKELY TO ACCUMULATE ON ROADS/SIDEWALKS TODAY. LAKE AND PORTER
COUNTY LOOK TO BE GROUND ZERO FOR THE LAKE EFFECT TODAY WITH THE
PRECIP LIKELY MAKING IT WELL INLAND TO JASPER AND NEWTON COUNTIES.
SOME HIGH RES GUIDANCE DOES CLIP SE COOK AND EASTERN WILL WITH LAKE
EFFECT PRECIP TODAY WHICH ISNT OUT OF THE QUESTION AND HAVE
MAINTAINED LOW POPS THERE.

THIS EVENING THE LOW LEVEL FLOW WILL GRADUALLY VEER AND SEND THE
LAKE EFFECT MORE INTO EASTERN COOK/EASTERN WILL/WESTERN LAKE IN (AND
EVEN POINTS SOUTH. BY THIS EVENING THE BOUNDARY LAYER FLOW WILL BE
WEAKENING AND THE TEMPS OUTSIDE OF THE LAKE INFLUENCED AREAS
DROPPING WHICH WOULD BOTH TEND TO FAVOR A TRANSITION TO A MORE
ORGANIZED DOMINANT SINGLE LAKE EFFECT BAND. MY BEST GUESS IS THAT
THE TIME WINDOW FOR THE HIGHEST PROBABILITY OF A DOMINANT LAKE
EFFECT BAND WITH POTENTIAL FOR HEAVY SNOW IS BETWEEN 23Z AND ABOUT
04Z. DURING THIS TIME PERIOD THE INSTABILITY (WHILE LESS THAN
EARLIER IN THE DAY) WILL STILL BE STRONG WITH INVERSION HEIGHTS
AROUND 10K FT AND LAKE-850 DELTA T VALUES >20C. DOES APPEARS A
PERIOD OF HEAVY SNOW COULD OCCUR IN EASTERN/SOUTHEASTERN COOK AND
EASTERN WILL COUNTIES EARLY THIS EVENING...BUT GIVEN THE LOW
CONFIDENCE OPTED NOT TO EXPAND THE WINTER WX HEADLINES AT THIS TIME
AND INSTEAD WILL ALLOW DAY SHIFT TO MONITOR MESOSCALE TRENDS. BY
LATER THIS EVENING INTO THE OVERNIGHT HOURS THE LAKE EFFECT
PARAMETERS WILL CONTINUE TO BECOME LESS FAVORABLE AND THE INTENSITY
OF THE LAKE EFFECT PRECIP SHOULD BEGIN TO WIND DOWN LATE TONIGHT AND
EVENTUALLY END SATURDAY. HAVE EXTENDED THE HIGHER POPS LATER IN TIME
AS LAKE EFFECT RARELY WINDS DOWN AS QUICKLY AS MODEL PROGGED
PARAMETERS SUGGEST IT WILL. WORTH NOTING THAT BY LATE EVENING AND
THROUGH SAT MORNING THE CONVECTIVE CLOUD TOP TEMPS DROP BELOW -12C
MEANING THE LIKELIHOOD OF CLOUDS CONTAINING ICE NUCLEI FOR SNOW WILL
BE LOW...SO DESPITE LOWER TEMPS IN THE BOUNDARY LAYER HAVE
TRANSITIONED P-TYPE BACK TO RAIN OR SNOW LATE TONIGHT AND SAT
MORNING.

FINALLY...HIGH WINDS WILL BE THE OTHER CONCERN TODAY. PLAN TO
MAINTAIN WIND ADVISORY AS IS THOUGH CONFIDENCE IN INLAND LOCATIONS
REACHING ADVISORY CRITERIA IS NOT THAT HIGH...BUT WITH GUSTS TO AT
LEAST 40 MPH A GOOD BET NOTHING WOULD BE GAINED FROM MAKING ANY
CHANGES TO THE HEADLINES. THE STORM WARNING FOR THE LAKE LOOKS
LIKELY TO VERIFY WITH 40 MPH SUSTAINED AND POSSIBLY GUSTS TO 58 MPH
LIKELY ALONG THE LAKE FRONT TODAY AND REALLY NOT COMFORTABLE NOT
HAVING A WARNING WITH THE POTENTIAL FOR DAMAGING WINDS ALONG THE
LAKE...SO AM GOING TO UPGRADE TO A HIGH WIND WARNING FOR LAKE SHORE
AREAS.

HEADLINES ARE AN ABSOLUTE MESS AND HEADACHE. WINTER WX ADVISORY
COVERS WIND AND SNOW...BUT IN ORDER TO GO WITH WARNING FOR WIND
ALONG THE LAKE FRONT IN INDIANA WOULD NEED TO UPGRADE TO A WINTER
STORM WARNING WHICH REALLY DOESNT SEEM TO BE THE BEST PRODUCT. AFTER
MUCH HEMMING AND HAWING AND INTERNAL COORDINATION HAVE OPTED TO
CHANGE THE WINTER WX ADV TO A LAKE EFFECT SNOW ADVISORY AND ISSUE A
WIND ADVISORY FOR JASPER AND NEWTON AND A HIGH WIND WARNING FOR LAKE
SHORE AREAS OF COOK...PORTER...AND LAKE IN. MAY NEED TO REPLACE THE
HIGH WIND WARNING WITH A WIND ADVISORY BY EARLY EVENING FOR

IZZI

&&

.LONG TERM...
325 AM CDT

SATURDAY NIGHT THROUGH THURSDAY...

MUCH...MUCH QUIETER SUNDAY AND MONDAY WITH MODERATING TEMPS. SLOW
MOVING FRONT COULD BRING A SOMEWHAT PROLONGED PERIOD OF RAIN/SHOWERS
MONDAY NIGHT THOUGH TUESDAY NIGHT. GENERALLY SEASONABLE TEMPS
EXPECTED THROUGH THE EXTENDED.

IZZI

&&

.AVIATION...

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

* INTERMITTENT RAIN SHOWERS OVERNIGHT.

* FEW HOUR PERIOD OF SNOW SHOWERS AFTER DAYBREAK.

* NORTHWEST WINDS SHIFTING NORTH AFTER DAYBREAK WITH GUSTS
  INCREASING TO 35-40 KT. NOT CLEAR ON FREQUENCY OF 40 KT GUSTS.

* PERIODIC MVFR CIGS OVERNIGHT THROUGH THE MORNING.

* LAKE EFFECT SNOW SHOWERS COULD AFFECT MDW EARLY EVENING.

MDB

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

NUMEROUS FORECAST CONCERNS CONTINUE WITH LOW PRESSURE OVER LAKE
HURON TRACKING SOUTHEAST AND VERY STRONG HIGH PRESSURE OVER THE
NORTHERN PLAINS TRAILING IT. WINDS ARE BEGINNING TO TURN NORTHWEST
WITH A COLD FRONT ENTERING NORTHWEST ILLINOIS AT 06Z AND MOVING
SOUTHEAST. WINDS WILL INCREASE IN SPEED OVER THE NEXT SEVERAL
HOURS. A SERIES OF UPPER DISTURBANCES WILL CROSS THE AREA THROUGH
THE MORNING WITH THE FIRST NOW BRINGING RAIN SHOWERS TO THE
TERMINALS. THE NEXT WILL ARRIVE OVERNIGHT BRINGING INTERMITTENT
SHOWERS WITH A BETTER DEFINED WAVE CROSSING THE AREA AROUND/AFTER
DAYBREAK BRINGING SNOW SHOWERS AS MUCH COLDER AIR ARRIVES. AREAS
OF NORTHERN WISCONSIN ARE SEEING IFR SNOW THIS HOUR BUT THESE
HEAVIER BURSTS ARE EXPECTED TO TRACK TO THE EAST OF THE TERMINALS.
STILL CANNOT RULE OUT A BRIEF HEAVIER BURST OF NON-ACCUMULATING
SNOW AT ORD/MDW/GYY BUT WILL CONTINUE WITH MINIMAL VSBY
RESTRICTION. OTHERWISE EXPECT INTERMITTENT MVFR CIGS TO DEVELOP
WITH QUITE A BIT OF VARIABILITY BASED ON UPSTREAM CONDITIONS.

WINDS FURTHER INCREASE BEHIND THIS SNOW PRODUCING WAVE WITH GUSTS
OF 35-40 KT EXPECTED. IT IS UNCLEAR HOW FREQUENT THAT 40 KT GUSTS
WILL OCCUR BUT AM FAIRLY CONFIDENT THAT THEY WILL. AM THINKING
THAT THERE MAY BE TWO SEPARATE WINDOWS WHERE 40 KT WILL BE MOST
LIKELY...ONE BEING MID/LATE MORNING BEHIND THE SNOW PRODUCING WAVE
AND THE OTHER BEING MID AFTERNOON WHEN SKIES ARE MOST LIKELY TO
SCATTER. WITH OVERALL CONFIDENCE IN 40 KT FREQUENCY ON THE LOW
SIDE WILL CONTINUE WITH PREVIOUS DURATION FOR NOW BUT WILL ATTEMPT
TO REFINE WITH THE NEXT UPDATE IF POSSIBLE.

THE NEXT ISSUE WILL BE LAKE EFFECT PRECIPITATION. GYY LOOKS TO BE
IN LINE FOR LAKE EFFECT RAIN/SNOW AND POSSIBLY PERIODS OF ALL SNOW
FROM LATE MORNING INTO THE EVENING. THUNDER IS ALSO POSSIBLE AS
CONDITIONS BECOME QUITE UNSTABLE OVER THE LAKE. MAY NEED TO
INDICATE SUB 1SM VSBY IN MODERATE/HEAVY PRECIPITATION AS DETAILS
BECOME MORE CLEAR. GYY WILL ALSO LIKELY SEE THE STRONGEST WINDS
GIVEN THEIR PROXIMITY TO THE LAKE AND 45+ KT WILL BE POSSIBLE.

WINDS GRADUALLY EASE EARLY THIS EVENING AND LAKE EFFECT MAY BEGIN
TO TRANSITION WESTWARD INTO THE EARLY OVERNIGHT SO MDW AND
POSSIBLY ORD COULD BE IN LINE FOR SOME SNOW SHOWERS BUT CONDITIONS
WILL BECOME LESS FAVORABLE WITH TIME INTO SATURDAY MORNING. WILL
CONTINUE WITH SNOW SHOWER MENTION AT MDW THIS EVENING BUT LEAVE
ORD DRY FOR NOW.

MDB

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

* HIGH CONFIDENCE IN PRECIP TRENDS THROUGH THE MORNING.

* MEDIUM CONFIDENCE IN SOME SNOW SHOWERS THIS MORNING...LOW
  CONFIDENCE IN DURATION/INTENSITY.

* HIGH CONFIDENCE IN NORTHWEST WINDS TURNING NORTH AND IN GUSTS
  REACHING 35-37 KT...MEDIUM CONFIDENCE THAT SOME 40 KT GUSTS WILL
  OCCUR BUT LOW CONFIDENCE IN FREQUENCY AND BEST TIMING.

* MEDIUM-HIGH CONFIDENCE IN PERIODIC MVFR CIGS OVERNIGHT THROUGH
  THE MORNING.

* LOW CONFIDENCE IN LAKE EFFECT SNOW SHOWER POTENTIAL THIS
  EVENING.

MDB

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

* SATURDAY...DRY/VFR. NORTHEAST WINDS 10-15 KT.
* SUNDAY...DRY/VFR. SOUTH WINDS 10-15 KT.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.
* TUESDAY...SHRA/MVFR LIKELY. SOUTHWEST WINDS.
* WEDNESDAY...DRY/VFR. SOUTHWEST WINDS.

&&

.MARINE...
256 AM CDT

A MAJOR WIND EVENT CONTINUES TO TAKE SHAPE FOR LAKE MICHIGAN EARLY
THIS MORNING. FAIRLY BROAD LOW PRESSURE OVER LAKE HURON WILL TRACK
SOUTHEAST TO LAKE ERIE BY MIDDAY THEN CONTINUE TO THE CAROLINA COAST
TONIGHT AND MERGE WITH DEVELOPING LOW PRESSURE. VERY STRONG HIGH
PRESSURE STRETCHED ACROSS THE NORTHERN PLAINS INTO CENTRAL CANADA IS
THE KEY TO THE RAPIDLY INCREASING WINDS THAT ARE NOW REACHING THE
NORTHERN PORTION OF THE LAKE. THE PRESSURE GRADIENT WILL QUICKLY
INCREASE ACROSS THE LAKE INTO MID MORNING AS A COLD FRONT SWEEPS
ACROSS ALLOWING MUCH COLDER AIR TO SPREAD DOWN THE LAKE. NORTH WINDS
WILL LIKELY INCREASE TO STORM FORCE AROUND 50 KT FOR MOST OF THE
LAKE WITH THE FAR NORTHERN SECTION HOLDING AT GALES...THOUGH A FEW
50 KT GUSTS COULD OCCUR THIS MORNING. MAY SEE SOME 55 KT GUSTS AT
TIMES ACROSS THE SOUTH HALF OF THE LAKE...ESPECIALLY LATE THIS
MORNING INTO MIDDAY. THIS RAPID INCREASE IN WINDS AND STRONG
MIXING OVER THE LAKE WILL ALLOW FOR A RAPID BUILDING OF WAVES
THROUGH THE MORNING TO AROUND 20 FEET BY EARLY/MID AFTERNOON
ACROSS THE CENTRAL AND SOUTHERN PART OF THE LAKE. WILL CONTINUE
WITH 18-23 FT PREVAILING WAVES IN THE FORECAST FOR THESE AREAS.
WINDS WILL BEGIN TO EASE THIS EVENING AND TREND A BIT
NORTHEASTERLY. SHOULD SEE WINDS FALL BELOW GALE FORCE OVERNIGHT
BUT WINDS WILL BE SLOW TO DIMINISH SIGNIFICANTLY THROUGH MIDDAY
SATURDAY SO WAVES WILL LIKELY BE SLOW TO FALL AS WELL. WILL LEAVE
EXISTING GALE AND STORM WARNINGS AS-IS.

THE HIGH WILL PASS OVER THE LAKE SATURDAY EVENING THROUGH SUNDAY
KEEPING WINDS LIGHT BUT SOUTH TO SOUTHWEST WINDS WILL INCREASE
THROUGH THE DAY SUNDAY AND MAY PUSH 30 KT LATE SUNDAY
AFTERNOON/EVENING AS LOW PRESSURE TRACKS NORTHEAST ACROSS THE
NORTHERN PLAINS. SOUTHWEST WINDS WILL REMAIN STRONG THROUGH MONDAY
NIGHT THEN LET UP NORTH AS LOW PRESSURE TRACKS FROM THE SOUTHERN
PLAINS ACROSS NORTHERN LAKE MICHIGAN...WHILE THE SOUTH SEES BREEZY
CONDITIONS CONTINUE. WINDS TURN WESTERLY LATER TUESDAY AND
DIMINISH AS HIGH PRESSURE RIDGING EXTENDS ACROSS THE AREA.

MDB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WIND ADVISORY...ILZ014...7 AM FRIDAY TO 10 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022...7 AM
     FRIDAY TO 7 PM FRIDAY.

     WIND ADVISORY...ILZ023-ILZ033...10 AM FRIDAY TO 7 PM FRIDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011...10 AM
     FRIDAY TO 10 PM FRIDAY.

     WIND ADVISORY...INZ019...10 AM FRIDAY TO 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 PM FRIDAY TO
     4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
     LMZ878 UNTIL 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563 UNTIL 10 PM FRIDAY.

     GALE WARNING...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 4 AM SATURDAY.

     STORM WARNING...NEARSHORE WILMETTE HARBOR TO MICHIGAN CITY IN UNTIL 7 PM
     FRIDAY.

&&

$$

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

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
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000
FXUS63 KLOT 310801
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
301 AM CDT FRI OCT 31 2014

.UPDATE...
921 PM

MID-EVENING UPDATE...

HAVE MADE SOME ADDITIONAL MINOR REFINEMENTS TO POPS FOR SHOWERS WITH
APPROACHING COLD FRONT TONIGHT. MORE IMPORTANTLY...HAVE BUMPED QPF
AND SNOWFALL AMOUNTS ASSOCIATED WITH LAKE EFFECT PRECIPITATION
EXPECTED FRIDAY AFTERNOON AND EVENING IN NORTHWEST INDIANA.

COLD FRONT CONTINUES TO DEVELOP SOUTHEASTWARD ACROSS IOWA...
MINNESOTA AND SOUTHWEST WISCONSIN THIS EVENING...AS COLD CANADIAN
HIGH PRESSURE EXPANDS SOUTHEAST TOWARD THE REGION. GUSTY WINDS STILL
REMAIN A FEW HOURS AWAY FOR THE LOCAL FORECAST AREA WITH
STRENGTHENING GUSTS MORE SHARPLY FALLING TEMPERATURES AFTER
MIDNIGHT. GENERALLY WEAK RADAR ECHOES NOTED ACROSS THE REGION AS
COLD ADVECTION AND LOW-LEVEL FRONTOGENESIS STRENGTHENS UPSTREAM OF
THE CWA. HIGH-RES GUIDANCE CONTINUES TO DEPICT DEVELOPMENT OF
SCATTERED LIGHT SHOWERS/SPRINKLES AFTER MIDNIGHT AS THE COLDER AIR
SPREADS IN...AND HAVE LARGELY BASED HOURLY POP TRENDS ALONG THESE
TRENDS.

ALL HEADLINES REMAIN UNCHANGED THROUGH THE PERIOD...WITH NO CHANGES
IN EXPECTATIONS OF THE VERY GUSTY WINDS...AND THE RESULTING LARGE
WAVES AND LAKESHORE FLOOD POTENTIAL ALONG LAKE MICHIGAN. BECOMING A
BIT MORE CONCERNED ABOUT POTENTIAL FOR SIGNIFICANT LAKE EFFECT SNOW
OVER NORTHWEST INDIANA FRIDAY AFTERNOON/EVENING...AND EVEN PORTIONS
OF THE IL LAKE SHORE AREAS FRIDAY NIGHT. REALLY IMPRESSIVE
THERMODYNAMIC SET-UP WITH COLD AIR OVER WARM LAKE WATERS AND STRONG
UNIDIRECTIONAL NORTHERLY FETCH OVER THE LAKE. ALLOWING FOR LAKE
SURFACE TEMPS IN THE LOW 50S F...LAKE-850 HPA DELTA T APPROACHES 20
DEG C DURING THE PERIOD AND YIELDS LAKE-INDUCED FORECAST CAPES UP TO
1200 J/KG AND INVERSION LEVELS ABOVE 15 KFT. THE ONLY POTENTIAL
LIMITING FACTOR...AND ITEM OF GREAT UNCERTAINTY...IS THE WARMTH OF
THE WATER/SURFACE WET BULB TEMPS SUPPLIED BY THE LONG FETCH OVER
WARM WATERS. GIVEN STRONG INSTABILITY...WITH GOOD LIKELIHOOD OF
THUNDER...THERMODYNAMIC INSTABILITY MAY WELL BE ABLE TO OVERCOME
WARM LOW LEVELS AND PRODUCE ACCUMULATING WET SNOWFALL. WITH MUCH
UNCERTAINTY REMAINING...HAVE INCREASED QPF/SNOWFALL AMOUNTS SLIGHTLY
ACROSS NORTHWEST INDIANA FRI AFTERNOON/NIGHT TO THE 1-3 INCH
RANGE...AND HAVE INDICATED THE POTENTIAL FOR LOCALLY HIGHER AMOUNTS
IN THE ADVISORY WSW TEXT. IF COLUMN IS ABLE TO COOL SUFFICIENTLY FOR
LONG DURATION +SN/TSSN...COULD BE SEVERAL INCHES MORE IN SOME SPOTS.
IN ADDITION...THOUGH INSTABILITY WEAKENS LATER FRIDAY NIGHT AS WINDS
SHIFT NORTHEAST...EXPECT LESS INTENSE RAIN/SNOW OR ALL SNOW SHOWERS
TO IMPINGE UPON PARTS OF THE ILLINOIS SHORE AND STATELINE AREAS AS
WELL.

RATZER

&&

.SHORT TERM...
332 PM CDT...

THE MAIN FORECAST FOCUS THIS AFTERNOON CONTINUES TO CENTER AROUND
THE STORM SYSTEM EXPECTED IMPACT THE REGION LATE TONIGHT THROUGH
FRIDAY NIGHT. STRONG WINDS...AND THE POTENTIAL FOR SOME PERIODS OF
HEAVY LAKE EFFECT SNOW ARE THE PRIMARY CONCERNS.

WE ARE ISSUING A WIND ADVISORY FOR MOST OF THE EASTERN HALF OF THE
AREA...WITH THE EXCEPTION OF LAKE...PORTER...JASPER AND NEWTON
COUNTIES IN INDIANA...WHERE A WINTER WEATHER ADVISORY IS BEING
ISSUED. SEE BELOW FOR MORE DETAILS.

WATER VAPOR IMAGERY EARLY THIS AFTERNOON SHOWS A RATHER VIGOROUS
UPPER LEVEL IMPULSE NOW MOVING JUST EAST OF LAKE WINNIPEG AND OVER
FAR SOUTHWESTERN ONTARIO. THIS WAVE IS EXPECTED TO CONTINUE DIGGING
SOUTH-SOUTHEASTWARD TONIGHT ALONG THE EASTERN PERIPHERY OF AN UPPER
RIDGE...CURRENT CENTERED ACROSS THE INTER MOUNTAIN WEST. AS THIS
OCCURS...AN AREA OF SURFACE LOW PRESSURE WILL SHIFT SOUTHWARD ACROSS
LOWER MICHIGAN INTO FRIDAY MORNING. FARTHER NORTHWEST...A RATHER
STOUT 1036 MB HIGH IS ALSO EXPECTED TO RAPIDLY BUILD SOUTHEASTWARD
ACROSS THE DAKOTAS AND UPPER MIDWEST INTO FRIDAY. THIS STILL LOOKS
TO SET THE STAGE FOR STRONG NORTHERN WINDS ACROSS THE AREA DURING
THE DAY FRIDAY AS STRONG PRESSURE RISES AND STRONG COLD AIR
ADVECTION LEAD TO A QUICK RAMP UP OF NORTHERLY WINDS IN THE WAKE OF
A COLD FRONTAL PASSAGE LATE TONIGHT. MODEL SOUNDINGS ALL SUGGEST
MEAN MIXING LAYER WIND SPEEDS COULD TOP 40 KT ACROSS MAINLY THE
EASTERN HALF OF THE AREA INLAND FROM THE LAKE...MEANING WIND GUSTS
COULD EASILY REACH THIS MAGNITUDE IN MOST AREAS. HOWEVER...AREAS
DIRECTLY ADJACENT TO LAKE MICHIGAN IN NORTHEASTERN ILLINOIS AND
NORTHWESTERN INDIANA COULD EXPERIENCE EVEN STRONGER GUSTS UP AROUND
50 KT WITH THE STRONG NORTHERLY ONSHORE COMPONENT TO THE WINDS.
WINDS LOOK TO REMAIN INTO THE EVENING ON HALLOWEEN...THOUGH WIND
SPEEDS SHOULD GRADUALLY WEAKEN THROUGH THE NIGHT.

THE LAKE SHORE FLOOD ADVISORY WILL CONTINUE FOR AREAS NEAR THE LAKE
AS LARGE BATTERING WAVES IN EXCESS OF 20 FT APPEAR LIKELY...AND AS
THE PREVIOUS DISCUSSION MENTIONED...LAKE LEVELS ARE ABOUT 2 FT
HIGHER THAN PAST YEARS...WHICH COULD MAKE THE IMPACTS OF THESE WAVES
HIGHER THEN SIMILAR WAVE EVENTS IN THE PAST COUPLE OF YEARS.

DUE TO THE LIKELIHOOD OF THESE STRONG WINDS...WE HAVE ISSUED A WIND
ADVISORY FOR MUCH OF THE EASTERN HALF OF MY CWA. THIS
INCLUDES AREAS BASICALLY ALONG AND EAST OF A LINE FROM HARVARD
SOUTHWARD THROUGH KANKAKEE AND IROQUOIS COUNTIES. THE ONLY EXCEPTION
TO THIS WIND ADVISORY IS FOR LAKE COUNTY INDIANA...AS WELL AS
PORTER...JASPER AND NEWTON COUNTIES...WHERE A WINTER WEATHER
ADVISORY IS BEING ISSUED IN PLACE OF A WIND ADVISORY FOR THE
COMBINATION OF THESE STRONG WINDS AND ALSO THE INCREASING POTENTIAL
FOR SOME ACCUMULATING LAKE EFFECT SNOW ON FRIDAY INTO FRIDAY
EVENING.

PRECIPITATION WITH THE APPROACHING COLD FRONT AND UPPER LEVEL
IMPULSE WILL LIKELY BEGIN TO ENTER FAR NORTHERN ILLINOIS AFTER 10
PM THIS EVENING...AND BE IN THE FORM OF RAIN SHOWERS. THIS INITIAL
ROUND OF SHOWERS SHOULD MOVE SOUTHWARD ACROSS THE AREA THROUGH THE
NIGHT...IN CLOSE PROXIMITY THE INCREASING FRONTOGENESIS IN THE
VICINITY OF THE COLD FRONTAL BOUNDARY. THIS SHOULD BE A FAIRLY
PROGRESSIVE AREA OF SHOWERS...WITH MOST AREAS ACROSS NORTH CENTRAL
ILLINOIS DRYING OUT BY EARLY FRIDAY MORNING.

THE SECOND STAGE OF PRECIPITATION WILL BE MORE OF A TRUE LAKE EFFECT
SETUP. A COLD AIRMASS FEATURING -7 DEGREE C TEMPERATURES AT 850 MB
WILL MOVE OVER THE LAKE...WHICH IS CURRENTLY REPORTING A 53F (11.7C)
DEGREE WATER TEMPERATURE AT THE SOUTH BUOY. THEREFORE...DELTA T`S
SHOULD END UP VERY FAVORABLE AROUND 19 DEGREES C. IN ADDITION...DEEP
LAKE INDUCED INSTABILITY IS STILL EXPECTED...WITH EQUILIBRIUM LEVELS
LIKELY TO REACH OR EVEN EXCEED 16,000 FT AGL. THEREFORE...THE THREAT
FOR THUNDER AND LIGHTNING HAS NOT CHANGED...WITH CONVECTIVE
PROCESSES LIKELY TO BE MORE THAN DEEP ENOUGH THROUGH THE -10 TO
-20 LAYER TO RESULT IN GOOD CHARGE SEPARATION.

IT LOOKS AS THOUGH THIS LAKE EFFECT BAND COULD BEGIN TO SET UP
ACROSS NORTHWESTERN INDIANA AND PERHAPS PORTIONS OF SOUTHEASTERN
COOK COUNTY BY LATE FRIDAY MORNING. HI RES GUIDANCE SUGGESTS
UNCERTAINTY ON THE EXACT AREAS THAT WILL GET THIS LAKE EFFECT
BANDING. SOME HAVE HINTED IN A FARTHER WEST BAND...WHICH WOULD
IMPACT MORE OF THE CHICAGO AREA. HOWEVER...I THINK AT THIS POINT
AREAS IN NORTHWEST INDIANA WILL BE MORE FAVORED...WITH THE
LIKELIHOOD OF A NEARLY DUE NORTH BOUNDARY LAYER FLOW SETTING UP OVER
LAKE MICHIGAN. THIS WOULD TEND TO FAVOR BETTER BOUNDARY LAYER
CONVERGENCE ALONG THE SOUTHERN TIP OF LAKE MICHIGAN FRIDAY
AFTERNOON...WHICH SUGGESTS THAT PORTER AND LAKE INDIANA WILL BE MORE
IN LINE WITH THE POTENTIAL HEAVIER PRECIPITATION. DUE TO THE STRONG
WINDS...IT IS ALSO LIKELY THAT THIS LAKE EFFECT PRECIP COULD BE
DRIVEN WELL INLAND ACROSS NORTHWESTERN INDIANA...POSSIBLY IMPACTING
MUCH OF JASPER AND PORTER COUNTIES AS WELL.

UNCERTAINTY IN PRECIPITATION TYPE IS STILL SOMEWHAT HIGH...AS
SOME WARMER AIR MOVING OFF THE LAKE SHOULD MAKE BOUNDARY LAYER
TEMPERATURES MARGINAL FOR SNOW TO REACH THE SURFACE. HOWEVER...WITH
THE AFOREMENTIONED CONVECTIVE INSTABILITY AND THE GOOD POTENTIAL FOR
SOME HEAVIER PRECIP RATES...IT IS VERY MUCH IN THE REALM OF
POSSIBILITIES THAT ENHANCED DYNAMIC COOLING COULD RESULT IN A COLD
ENOUGH BOUNDARY LAYER SUPPORTIVE OF HEAVY SNOW. IT APPEARS THAT
AREAS INLAND FROM THE IMMEDIATE LAKE SHORE WOULD HAVE THE BEST
POTENTIAL FOR SNOW...THOUGH EVEN AREAS ALONG THE LAKE COULD CHANGE
OVER/MIX WITH SNOW. OVERALL...WITH THE POTENTIAL FOR SOME HEAVIER
BANDS OF SNOW WITH SOME ACCUMULATIONS POSSIBLE (POSSIBLY A FEW
INCHES IN SOME AREAS) ALONG WITH THE VERY STRONG NORTHERLY
WINDS...WE HAVE CHOSEN TO ISSUE THE WINTER WEATHER ADVISORY FOR THE
4 NORTHWESTERN INDIANA COUNTIES. IF...HOWEVER...THE TRANSITION TO
SNOW DOES NOT PAN OUT AS CURRENT THINKING SUGGESTS...WINDS WOULD BE
THE MAIN HAZARD ON FRIDAY...AND THE WINTER WEATHER ADVISORY COULD
THEN BE REPLACED WITH A WIND ADVISORY. THEREFORE...IN SPITE OF THE
UNCERTAINTIES ON WHEN CHANGE OVERS TO SNOW WILL OCCUR AND HOW MUCH
SNOW WILL ACTUALLY FALL...WE FEEL AT THIS POINT...TO ERROR ON THE
SIDE OF CAUTION...AS THERE IS A POTENTIAL FOR SOME VERY HEAVY SNOW
IN ADDITION TO THE STRONG WINDS.

THE WINDS ARE EXPECTED TO GRADUALLY VEER MORE NORTHEASTERLY FRIDAY
NIGHT...AND THIS COULD ALLOW SOME OF THE LAKE EFFECT PRECIPITATION
TO GET INTO NORTHEASTERN ILLINOIS FOR A BRIEF PERIOD FRIDAY EVENING.
HOWEVER...MODEL GUIDANCE CONTINUES TO SUGGEST THAT INVERSION HEIGHTS
WILL CRASH IN A HURRY BY LATE FRIDAY EVENING AS HEIGHTS AND
TEMPERATURES BEGIN TO RISE ALOFT. THEREFORE...ANY SNOW SHOWERS THAT
GET INTO NORTHEASTERN ILLINOIS WOULD LIKELY BE LIGHT AND COME TO AN
END LATE FRIDAY NIGHT/EARLY SAT MORNING.

HIGH TEMPERATURES AREA-WIDE LOOK TO REMAIN IN THE LOWER 40S AT BEST
ON FRIDAY AND SATURDAY

KJB

&&

.LONG TERM...

HIGH TEMPERATURES WILL MODERATE INTO EARLY NEXT WEEK AS THE
WESTERN CONUS UPPER RIDGE BUILDS EASTWARD OVER THE REGION. ANOTHER
COLD FRONT LOOKS TO TAKE AIM ON THE AREA AROUND NEXT
TUESDAY...WHICH WILL RESULT IN OUR NEXT CHANCE OF SHOWERS.
OTHERWISE TEMPERATURES LOOK TO REMAIN NEAR NORMAL DURING THE LATER
HALF OF THE WEEK.

KJB

&&

.AVIATION...

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

* INTERMITTENT RAIN SHOWERS OVERNIGHT.

* FEW HOUR PERIOD OF SNOW SHOWERS AFTER DAYBREAK.

* NORTHWEST WINDS SHIFTING NORTH AFTER DAYBREAK WITH GUSTS
  INCREASING TO 35-40 KT. NOT CLEAR ON FREQUENCY OF 40 KT GUSTS.

* PERIODIC MVFR CIGS OVERNIGHT THROUGH THE MORNING.

* LAKE EFFECT SNOW SHOWERS COULD AFFECT MDW EARLY EVENING.

MDB

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

NUMEROUS FORECAST CONCERNS CONTINUE WITH LOW PRESSURE OVER LAKE
HURON TRACKING SOUTHEAST AND VERY STRONG HIGH PRESSURE OVER THE
NORTHERN PLAINS TRAILING IT. WINDS ARE BEGINNING TO TURN NORTHWEST
WITH A COLD FRONT ENTERING NORTHWEST ILLINOIS AT 06Z AND MOVING
SOUTHEAST. WINDS WILL INCREASE IN SPEED OVER THE NEXT SEVERAL
HOURS. A SERIES OF UPPER DISTURBANCES WILL CROSS THE AREA THROUGH
THE MORNING WITH THE FIRST NOW BRINGING RAIN SHOWERS TO THE
TERMINALS. THE NEXT WILL ARRIVE OVERNIGHT BRINGING INTERMITTENT
SHOWERS WITH A BETTER DEFINED WAVE CROSSING THE AREA AROUND/AFTER
DAYBREAK BRINGING SNOW SHOWERS AS MUCH COLDER AIR ARRIVES. AREAS
OF NORTHERN WISCONSIN ARE SEEING IFR SNOW THIS HOUR BUT THESE
HEAVIER BURSTS ARE EXPECTED TO TRACK TO THE EAST OF THE TERMINALS.
STILL CANNOT RULE OUT A BRIEF HEAVIER BURST OF NON-ACCUMULATING
SNOW AT ORD/MDW/GYY BUT WILL CONTINUE WITH MINIMAL VSBY
RESTRICTION. OTHERWISE EXPECT INTERMITTENT MVFR CIGS TO DEVELOP
WITH QUITE A BIT OF VARIABILITY BASED ON UPSTREAM CONDITIONS.

WINDS FURTHER INCREASE BEHIND THIS SNOW PRODUCING WAVE WITH GUSTS
OF 35-40 KT EXPECTED. IT IS UNCLEAR HOW FREQUENT THAT 40 KT GUSTS
WILL OCCUR BUT AM FAIRLY CONFIDENT THAT THEY WILL. AM THINKING
THAT THERE MAY BE TWO SEPARATE WINDOWS WHERE 40 KT WILL BE MOST
LIKELY...ONE BEING MID/LATE MORNING BEHIND THE SNOW PRODUCING WAVE
AND THE OTHER BEING MID AFTERNOON WHEN SKIES ARE MOST LIKELY TO
SCATTER. WITH OVERALL CONFIDENCE IN 40 KT FREQUENCY ON THE LOW
SIDE WILL CONTINUE WITH PREVIOUS DURATION FOR NOW BUT WILL ATTEMPT
TO REFINE WITH THE NEXT UPDATE IF POSSIBLE.

THE NEXT ISSUE WILL BE LAKE EFFECT PRECIPITATION. GYY LOOKS TO BE
IN LINE FOR LAKE EFFECT RAIN/SNOW AND POSSIBLY PERIODS OF ALL SNOW
FROM LATE MORNING INTO THE EVENING. THUNDER IS ALSO POSSIBLE AS
CONDITIONS BECOME QUITE UNSTABLE OVER THE LAKE. MAY NEED TO
INDICATE SUB 1SM VSBY IN MODERATE/HEAVY PRECIPITATION AS DETAILS
BECOME MORE CLEAR. GYY WILL ALSO LIKELY SEE THE STRONGEST WINDS
GIVEN THEIR PROXIMITY TO THE LAKE AND 45+ KT WILL BE POSSIBLE.

WINDS GRADUALLY EASE EARLY THIS EVENING AND LAKE EFFECT MAY BEGIN
TO TRANSITION WESTWARD INTO THE EARLY OVERNIGHT SO MDW AND
POSSIBLY ORD COULD BE IN LINE FOR SOME SNOW SHOWERS BUT CONDITIONS
WILL BECOME LESS FAVORABLE WITH TIME INTO SATURDAY MORNING. WILL
CONTINUE WITH SNOW SHOWER MENTION AT MDW THIS EVENING BUT LEAVE
ORD DRY FOR NOW.

MDB

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

* HIGH CONFIDENCE IN PRECIP TRENDS THROUGH THE MORNING.

* MEDIUM CONFIDENCE IN SOME SNOW SHOWERS THIS MORNING...LOW
  CONFIDENCE IN DURATION/INTENSITY.

* HIGH CONFIDENCE IN NORTHWEST WINDS TURNING NORTH AND IN GUSTS
  REACHING 35-37 KT...MEDIUM CONFIDENCE THAT SOME 40 KT GUSTS WILL
  OCCUR BUT LOW CONFIDENCE IN FREQUENCY AND BEST TIMING.

* MEDIUM-HIGH CONFIDENCE IN PERIODIC MVFR CIGS OVERNIGHT THROUGH
  THE MORNING.

* LOW CONFIDENCE IN LAKE EFFECT SNOW SHOWER POTENTIAL THIS
  EVENING.

MDB

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

* SATURDAY...DRY/VFR. NORTHEAST WINDS 10-15 KT.
* SUNDAY...DRY/VFR. SOUTH WINDS 10-15 KT.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.
* TUESDAY...SHRA/MVFR LIKELY. SOUTHWEST WINDS.
* WEDNESDAY...DRY/VFR. SOUTHWEST WINDS.

&&

.MARINE...
256 AM CDT

A MAJOR WIND EVENT CONTINUES TO TAKE SHAPE FOR LAKE MICHIGAN EARLY
THIS MORNING. FAIRLY BROAD LOW PRESSURE OVER LAKE HURON WILL TRACK
SOUTHEAST TO LAKE ERIE BY MIDDAY THEN CONTINUE TO THE CAROLINA COAST
TONIGHT AND MERGE WITH DEVELOPING LOW PRESSURE. VERY STRONG HIGH
PRESSURE STRETCHED ACROSS THE NORTHERN PLAINS INTO CENTRAL CANADA IS
THE KEY TO THE RAPIDLY INCREASING WINDS THAT ARE NOW REACHING THE
NORTHERN PORTION OF THE LAKE. THE PRESSURE GRADIENT WILL QUICKLY
INCREASE ACROSS THE LAKE INTO MID MORNING AS A COLD FRONT SWEEPS
ACROSS ALLOWING MUCH COLDER AIR TO SPREAD DOWN THE LAKE. NORTH WINDS
WILL LIKELY INCREASE TO STORM FORCE AROUND 50 KT FOR MOST OF THE
LAKE WITH THE FAR NORTHERN SECTION HOLDING AT GALES...THOUGH A FEW
50 KT GUSTS COULD OCCUR THIS MORNING. MAY SEE SOME 55 KT GUSTS AT
TIMES ACROSS THE SOUTH HALF OF THE LAKE...ESPECIALLY LATE THIS
MORNING INTO MIDDAY. THIS RAPID INCREASE IN WINDS AND STRONG
MIXING OVER THE LAKE WILL ALLOW FOR A RAPID BUILDING OF WAVES
THROUGH THE MORNING TO AROUND 20 FEET BY EARLY/MID AFTERNOON
ACROSS THE CENTRAL AND SOUTHERN PART OF THE LAKE. WILL CONTINUE
WITH 18-23 FT PREVAILING WAVES IN THE FORECAST FOR THESE AREAS.
WINDS WILL BEGIN TO EASE THIS EVENING AND TREND A BIT
NORTHEASTERLY. SHOULD SEE WINDS FALL BELOW GALE FORCE OVERNIGHT
BUT WINDS WILL BE SLOW TO DIMINISH SIGNIFICANTLY THROUGH MIDDAY
SATURDAY SO WAVES WILL LIKELY BE SLOW TO FALL AS WELL. WILL LEAVE
EXISTING GALE AND STORM WARNINGS AS-IS.

THE HIGH WILL PASS OVER THE LAKE SATURDAY EVENING THROUGH SUNDAY
KEEPING WINDS LIGHT BUT SOUTH TO SOUTHWEST WINDS WILL INCREASE
THROUGH THE DAY SUNDAY AND MAY PUSH 30 KT LATE SUNDAY
AFTERNOON/EVENING AS LOW PRESSURE TRACKS NORTHEAST ACROSS THE
NORTHERN PLAINS. SOUTHWEST WINDS WILL REMAIN STRONG THROUGH MONDAY
NIGHT THEN LET UP NORTH AS LOW PRESSURE TRACKS FROM THE SOUTHERN
PLAINS ACROSS NORTHERN LAKE MICHIGAN...WHILE THE SOUTH SEES BREEZY
CONDITIONS CONTINUE. WINDS TURN WESTERLY LATER TUESDAY AND
DIMINISH AS HIGH PRESSURE RIDGING EXTENDS ACROSS THE AREA.

MDB

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WIND ADVISORY...ILZ014...7 AM FRIDAY TO 10 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022...7 AM
     FRIDAY TO 7 PM FRIDAY.

     WIND ADVISORY...ILZ023-ILZ033...10 AM FRIDAY TO 7 PM FRIDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011...10 AM
     FRIDAY TO 10 PM FRIDAY.

     WIND ADVISORY...INZ019...10 AM FRIDAY TO 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 PM FRIDAY TO
     4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
     LMZ878 UNTIL 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563 UNTIL 10 PM FRIDAY.

     GALE WARNING...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 4 AM SATURDAY.

     STORM WARNING...NEARSHORE WILMETTE HARBOR TO MICHIGAN CITY IN UNTIL 7 PM
     FRIDAY.

&&

$$

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

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






000
FXUS63 KLOT 310613
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
113 AM CDT FRI OCT 31 2014

.UPDATE...
921 PM

MID-EVENING UPDATE...

HAVE MADE SOME ADDITIONAL MINOR REFINEMENTS TO POPS FOR SHOWERS WITH
APPROACHING COLD FRONT TONIGHT. MORE IMPORTANTLY...HAVE BUMPED QPF
AND SNOWFALL AMOUNTS ASSOCIATED WITH LAKE EFFECT PRECIPITATION
EXPECTED FRIDAY AFTERNOON AND EVENING IN NORTHWEST INDIANA.

COLD FRONT CONTINUES TO DEVELOP SOUTHEASTWARD ACROSS IOWA...
MINNESOTA AND SOUTHWEST WISCONSIN THIS EVENING...AS COLD CANADIAN
HIGH PRESSURE EXPANDS SOUTHEAST TOWARD THE REGION. GUSTY WINDS STILL
REMAIN A FEW HOURS AWAY FOR THE LOCAL FORECAST AREA WITH
STRENGTHENING GUSTS MORE SHARPLY FALLING TEMPERATURES AFTER
MIDNIGHT. GENERALLY WEAK RADAR ECHOES NOTED ACROSS THE REGION AS
COLD ADVECTION AND LOW-LEVEL FRONTOGENESIS STRENGTHENS UPSTREAM OF
THE CWA. HIGH-RES GUIDANCE CONTINUES TO DEPICT DEVELOPMENT OF
SCATTERED LIGHT SHOWERS/SPRINKLES AFTER MIDNIGHT AS THE COLDER AIR
SPREADS IN...AND HAVE LARGELY BASED HOURLY POP TRENDS ALONG THESE
TRENDS.

ALL HEADLINES REMAIN UNCHANGED THROUGH THE PERIOD...WITH NO CHANGES
IN EXPECTATIONS OF THE VERY GUSTY WINDS...AND THE RESULTING LARGE
WAVES AND LAKESHORE FLOOD POTENTIAL ALONG LAKE MICHIGAN. BECOMING A
BIT MORE CONCERNED ABOUT POTENTIAL FOR SIGNIFICANT LAKE EFFECT SNOW
OVER NORTHWEST INDIANA FRIDAY AFTERNOON/EVENING...AND EVEN PORTIONS
OF THE IL LAKE SHORE AREAS FRIDAY NIGHT. REALLY IMPRESSIVE
THERMODYNAMIC SET-UP WITH COLD AIR OVER WARM LAKE WATERS AND STRONG
UNIDIRECTIONAL NORTHERLY FETCH OVER THE LAKE. ALLOWING FOR LAKE
SURFACE TEMPS IN THE LOW 50S F...LAKE-850 HPA DELTA T APPROACHES 20
DEG C DURING THE PERIOD AND YIELDS LAKE-INDUCED FORECAST CAPES UP TO
1200 J/KG AND INVERSION LEVELS ABOVE 15 KFT. THE ONLY POTENTIAL
LIMITING FACTOR...AND ITEM OF GREAT UNCERTAINTY...IS THE WARMTH OF
THE WATER/SURFACE WET BULB TEMPS SUPPLIED BY THE LONG FETCH OVER
WARM WATERS. GIVEN STRONG INSTABILITY...WITH GOOD LIKELIHOOD OF
THUNDER...THERMODYNAMIC INSTABILITY MAY WELL BE ABLE TO OVERCOME
WARM LOW LEVELS AND PRODUCE ACCUMULATING WET SNOWFALL. WITH MUCH
UNCERTAINTY REMAINING...HAVE INCREASED QPF/SNOWFALL AMOUNTS SLIGHTLY
ACROSS NORTHWEST INDIANA FRI AFTERNOON/NIGHT TO THE 1-3 INCH
RANGE...AND HAVE INDICATED THE POTENTIAL FOR LOCALLY HIGHER AMOUNTS
IN THE ADVISORY WSW TEXT. IF COLUMN IS ABLE TO COOL SUFFICIENTLY FOR
LONG DURATION +SN/TSSN...COULD BE SEVERAL INCHES MORE IN SOME SPOTS.
IN ADDITION...THOUGH INSTABILITY WEAKENS LATER FRIDAY NIGHT AS WINDS
SHIFT NORTHEAST...EXPECT LESS INTENSE RAIN/SNOW OR ALL SNOW SHOWERS
TO IMPINGE UPON PARTS OF THE ILLINOIS SHORE AND STATELINE AREAS AS
WELL.

RATZER

&&

.SHORT TERM...
332 PM CDT...

THE MAIN FORECAST FOCUS THIS AFTERNOON CONTINUES TO CENTER AROUND
THE STORM SYSTEM EXPECTED IMPACT THE REGION LATE TONIGHT THROUGH
FRIDAY NIGHT. STRONG WINDS...AND THE POTENTIAL FOR SOME PERIODS OF
HEAVY LAKE EFFECT SNOW ARE THE PRIMARY CONCERNS.

WE ARE ISSUING A WIND ADVISORY FOR MOST OF THE EASTERN HALF OF THE
AREA...WITH THE EXCEPTION OF LAKE...PORTER...JASPER AND NEWTON
COUNTIES IN INDIANA...WHERE A WINTER WEATHER ADVISORY IS BEING
ISSUED. SEE BELOW FOR MORE DETAILS.

WATER VAPOR IMAGERY EARLY THIS AFTERNOON SHOWS A RATHER VIGOROUS
UPPER LEVEL IMPULSE NOW MOVING JUST EAST OF LAKE WINNIPEG AND OVER
FAR SOUTHWESTERN ONTARIO. THIS WAVE IS EXPECTED TO CONTINUE DIGGING
SOUTH-SOUTHEASTWARD TONIGHT ALONG THE EASTERN PERIPHERY OF AN UPPER
RIDGE...CURRENT CENTERED ACROSS THE INTER MOUNTAIN WEST. AS THIS
OCCURS...AN AREA OF SURFACE LOW PRESSURE WILL SHIFT SOUTHWARD ACROSS
LOWER MICHIGAN INTO FRIDAY MORNING. FARTHER NORTHWEST...A RATHER
STOUT 1036 MB HIGH IS ALSO EXPECTED TO RAPIDLY BUILD SOUTHEASTWARD
ACROSS THE DAKOTAS AND UPPER MIDWEST INTO FRIDAY. THIS STILL LOOKS
TO SET THE STAGE FOR STRONG NORTHERN WINDS ACROSS THE AREA DURING
THE DAY FRIDAY AS STRONG PRESSURE RISES AND STRONG COLD AIR
ADVECTION LEAD TO A QUICK RAMP UP OF NORTHERLY WINDS IN THE WAKE OF
A COLD FRONTAL PASSAGE LATE TONIGHT. MODEL SOUNDINGS ALL SUGGEST
MEAN MIXING LAYER WIND SPEEDS COULD TOP 40 KT ACROSS MAINLY THE
EASTERN HALF OF THE AREA INLAND FROM THE LAKE...MEANING WIND GUSTS
COULD EASILY REACH THIS MAGNITUDE IN MOST AREAS. HOWEVER...AREAS
DIRECTLY ADJACENT TO LAKE MICHIGAN IN NORTHEASTERN ILLINOIS AND
NORTHWESTERN INDIANA COULD EXPERIENCE EVEN STRONGER GUSTS UP AROUND
50 KT WITH THE STRONG NORTHERLY ONSHORE COMPONENT TO THE WINDS.
WINDS LOOK TO REMAIN INTO THE EVENING ON HALLOWEEN...THOUGH WIND
SPEEDS SHOULD GRADUALLY WEAKEN THROUGH THE NIGHT.

THE LAKE SHORE FLOOD ADVISORY WILL CONTINUE FOR AREAS NEAR THE LAKE
AS LARGE BATTERING WAVES IN EXCESS OF 20 FT APPEAR LIKELY...AND AS
THE PREVIOUS DISCUSSION MENTIONED...LAKE LEVELS ARE ABOUT 2 FT
HIGHER THAN PAST YEARS...WHICH COULD MAKE THE IMPACTS OF THESE WAVES
HIGHER THEN SIMILAR WAVE EVENTS IN THE PAST COUPLE OF YEARS.

DUE TO THE LIKELIHOOD OF THESE STRONG WINDS...WE HAVE ISSUED A WIND
ADVISORY FOR MUCH OF THE EASTERN HALF OF MY CWA. THIS
INCLUDES AREAS BASICALLY ALONG AND EAST OF A LINE FROM HARVARD
SOUTHWARD THROUGH KANKAKEE AND IROQUOIS COUNTIES. THE ONLY EXCEPTION
TO THIS WIND ADVISORY IS FOR LAKE COUNTY INDIANA...AS WELL AS
PORTER...JASPER AND NEWTON COUNTIES...WHERE A WINTER WEATHER
ADVISORY IS BEING ISSUED IN PLACE OF A WIND ADVISORY FOR THE
COMBINATION OF THESE STRONG WINDS AND ALSO THE INCREASING POTENTIAL
FOR SOME ACCUMULATING LAKE EFFECT SNOW ON FRIDAY INTO FRIDAY
EVENING.

PRECIPITATION WITH THE APPROACHING COLD FRONT AND UPPER LEVEL
IMPULSE WILL LIKELY BEGIN TO ENTER FAR NORTHERN ILLINOIS AFTER 10
PM THIS EVENING...AND BE IN THE FORM OF RAIN SHOWERS. THIS INITIAL
ROUND OF SHOWERS SHOULD MOVE SOUTHWARD ACROSS THE AREA THROUGH THE
NIGHT...IN CLOSE PROXIMITY THE INCREASING FRONTOGENESIS IN THE
VICINITY OF THE COLD FRONTAL BOUNDARY. THIS SHOULD BE A FAIRLY
PROGRESSIVE AREA OF SHOWERS...WITH MOST AREAS ACROSS NORTH CENTRAL
ILLINOIS DRYING OUT BY EARLY FRIDAY MORNING.

THE SECOND STAGE OF PRECIPITATION WILL BE MORE OF A TRUE LAKE EFFECT
SETUP. A COLD AIRMASS FEATURING -7 DEGREE C TEMPERATURES AT 850 MB
WILL MOVE OVER THE LAKE...WHICH IS CURRENTLY REPORTING A 53F (11.7C)
DEGREE WATER TEMPERATURE AT THE SOUTH BUOY. THEREFORE...DELTA T`S
SHOULD END UP VERY FAVORABLE AROUND 19 DEGREES C. IN ADDITION...DEEP
LAKE INDUCED INSTABILITY IS STILL EXPECTED...WITH EQUILIBRIUM LEVELS
LIKELY TO REACH OR EVEN EXCEED 16,000 FT AGL. THEREFORE...THE THREAT
FOR THUNDER AND LIGHTNING HAS NOT CHANGED...WITH CONVECTIVE
PROCESSES LIKELY TO BE MORE THAN DEEP ENOUGH THROUGH THE -10 TO
-20 LAYER TO RESULT IN GOOD CHARGE SEPARATION.

IT LOOKS AS THOUGH THIS LAKE EFFECT BAND COULD BEGIN TO SET UP
ACROSS NORTHWESTERN INDIANA AND PERHAPS PORTIONS OF SOUTHEASTERN
COOK COUNTY BY LATE FRIDAY MORNING. HI RES GUIDANCE SUGGESTS
UNCERTAINTY ON THE EXACT AREAS THAT WILL GET THIS LAKE EFFECT
BANDING. SOME HAVE HINTED IN A FARTHER WEST BAND...WHICH WOULD
IMPACT MORE OF THE CHICAGO AREA. HOWEVER...I THINK AT THIS POINT
AREAS IN NORTHWEST INDIANA WILL BE MORE FAVORED...WITH THE
LIKELIHOOD OF A NEARLY DUE NORTH BOUNDARY LAYER FLOW SETTING UP OVER
LAKE MICHIGAN. THIS WOULD TEND TO FAVOR BETTER BOUNDARY LAYER
CONVERGENCE ALONG THE SOUTHERN TIP OF LAKE MICHIGAN FRIDAY
AFTERNOON...WHICH SUGGESTS THAT PORTER AND LAKE INDIANA WILL BE MORE
IN LINE WITH THE POTENTIAL HEAVIER PRECIPITATION. DUE TO THE STRONG
WINDS...IT IS ALSO LIKELY THAT THIS LAKE EFFECT PRECIP COULD BE
DRIVEN WELL INLAND ACROSS NORTHWESTERN INDIANA...POSSIBLY IMPACTING
MUCH OF JASPER AND PORTER COUNTIES AS WELL.

UNCERTAINTY IN PRECIPITATION TYPE IS STILL SOMEWHAT HIGH...AS
SOME WARMER AIR MOVING OFF THE LAKE SHOULD MAKE BOUNDARY LAYER
TEMPERATURES MARGINAL FOR SNOW TO REACH THE SURFACE. HOWEVER...WITH
THE AFOREMENTIONED CONVECTIVE INSTABILITY AND THE GOOD POTENTIAL FOR
SOME HEAVIER PRECIP RATES...IT IS VERY MUCH IN THE REALM OF
POSSIBILITIES THAT ENHANCED DYNAMIC COOLING COULD RESULT IN A COLD
ENOUGH BOUNDARY LAYER SUPPORTIVE OF HEAVY SNOW. IT APPEARS THAT
AREAS INLAND FROM THE IMMEDIATE LAKE SHORE WOULD HAVE THE BEST
POTENTIAL FOR SNOW...THOUGH EVEN AREAS ALONG THE LAKE COULD CHANGE
OVER/MIX WITH SNOW. OVERALL...WITH THE POTENTIAL FOR SOME HEAVIER
BANDS OF SNOW WITH SOME ACCUMULATIONS POSSIBLE (POSSIBLY A FEW
INCHES IN SOME AREAS) ALONG WITH THE VERY STRONG NORTHERLY
WINDS...WE HAVE CHOSEN TO ISSUE THE WINTER WEATHER ADVISORY FOR THE
4 NORTHWESTERN INDIANA COUNTIES. IF...HOWEVER...THE TRANSITION TO
SNOW DOES NOT PAN OUT AS CURRENT THINKING SUGGESTS...WINDS WOULD BE
THE MAIN HAZARD ON FRIDAY...AND THE WINTER WEATHER ADVISORY COULD
THEN BE REPLACED WITH A WIND ADVISORY. THEREFORE...IN SPITE OF THE
UNCERTAINTIES ON WHEN CHANGE OVERS TO SNOW WILL OCCUR AND HOW MUCH
SNOW WILL ACTUALLY FALL...WE FEEL AT THIS POINT...TO ERROR ON THE
SIDE OF CAUTION...AS THERE IS A POTENTIAL FOR SOME VERY HEAVY SNOW
IN ADDITION TO THE STRONG WINDS.

THE WINDS ARE EXPECTED TO GRADUALLY VEER MORE NORTHEASTERLY FRIDAY
NIGHT...AND THIS COULD ALLOW SOME OF THE LAKE EFFECT PRECIPITATION
TO GET INTO NORTHEASTERN ILLINOIS FOR A BRIEF PERIOD FRIDAY EVENING.
HOWEVER...MODEL GUIDANCE CONTINUES TO SUGGEST THAT INVERSION HEIGHTS
WILL CRASH IN A HURRY BY LATE FRIDAY EVENING AS HEIGHTS AND
TEMPERATURES BEGIN TO RISE ALOFT. THEREFORE...ANY SNOW SHOWERS THAT
GET INTO NORTHEASTERN ILLINOIS WOULD LIKELY BE LIGHT AND COME TO AN
END LATE FRIDAY NIGHT/EARLY SAT MORNING.

HIGH TEMPERATURES AREA-WIDE LOOK TO REMAIN IN THE LOWER 40S AT BEST
ON FRIDAY AND SATURDAY

KJB

&&

.LONG TERM...

HIGH TEMPERATURES WILL MODERATE INTO EARLY NEXT WEEK AS THE
WESTERN CONUS UPPER RIDGE BUILDS EASTWARD OVER THE REGION. ANOTHER
COLD FRONT LOOKS TO TAKE AIM ON THE AREA AROUND NEXT
TUESDAY...WHICH WILL RESULT IN OUR NEXT CHANCE OF SHOWERS.
OTHERWISE TEMPERATURES LOOK TO REMAIN NEAR NORMAL DURING THE LATER
HALF OF THE WEEK.

KJB

&&

.AVIATION...

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

* INTERMITTENT RAIN SHOWERS OVERNIGHT.

* FEW HOUR PERIOD OF SNOW SHOWERS AFTER DAYBREAK.

* NORTHWEST WINDS SHIFTING NORTH AFTER DAYBREAK WITH GUSTS
  INCREASING TO 35-40 KT. NOT CLEAR ON FREQUENCY OF 40 KT GUSTS.

* PERIODIC MVFR CIGS OVERNIGHT THROUGH THE MORNING.

* LAKE EFFECT SNOW SHOWERS COULD AFFECT MDW EARLY EVENING.

MDB

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

NUMEROUS FORECAST CONCERNS CONTINUE WITH LOW PRESSURE OVER LAKE
HURON TRACKING SOUTHEAST AND VERY STRONG HIGH PRESSURE OVER THE
NORTHERN PLAINS TRAILING IT. WINDS ARE BEGINNING TO TURN NORTHWEST
WITH A COLD FRONT ENTERING NORTHWEST ILLINOIS AT 06Z AND MOVING
SOUTHEAST. WINDS WILL INCREASE IN SPEED OVER THE NEXT SEVERAL
HOURS. A SERIES OF UPPER DISTURBANCES WILL CROSS THE AREA THROUGH
THE MORNING WITH THE FIRST NOW BRINGING RAIN SHOWERS TO THE
TERMINALS. THE NEXT WILL ARRIVE OVERNIGHT BRINGING INTERMITTENT
SHOWERS WITH A BETTER DEFINED WAVE CROSSING THE AREA AROUND/AFTER
DAYBREAK BRINGING SNOW SHOWERS AS MUCH COLDER AIR ARRIVES. AREAS
OF NORTHERN WISCONSIN ARE SEEING IFR SNOW THIS HOUR BUT THESE
HEAVIER BURSTS ARE EXPECTED TO TRACK TO THE EAST OF THE TERMINALS.
STILL CANNOT RULE OUT A BRIEF HEAVIER BURST OF NON-ACCUMULATING
SNOW AT ORD/MDW/GYY BUT WILL CONTINUE WITH MINIMAL VSBY
RESTRICTION. OTHERWISE EXPECT INTERMITTENT MVFR CIGS TO DEVELOP
WITH QUITE A BIT OF VARIABILITY BASED ON UPSTREAM CONDITIONS.

WINDS FURTHER INCREASE BEHIND THIS SNOW PRODUCING WAVE WITH GUSTS
OF 35-40 KT EXPECTED. IT IS UNCLEAR HOW FREQUENT THAT 40 KT GUSTS
WILL OCCUR BUT AM FAIRLY CONFIDENT THAT THEY WILL. AM THINKING
THAT THERE MAY BE TWO SEPARATE WINDOWS WHERE 40 KT WILL BE MOST
LIKELY...ONE BEING MID/LATE MORNING BEHIND THE SNOW PRODUCING WAVE
AND THE OTHER BEING MID AFTERNOON WHEN SKIES ARE MOST LIKELY TO
SCATTER. WITH OVERALL CONFIDENCE IN 40 KT FREQUENCY ON THE LOW
SIDE WILL CONTINUE WITH PREVIOUS DURATION FOR NOW BUT WILL ATTEMPT
TO REFINE WITH THE NEXT UPDATE IF POSSIBLE.

THE NEXT ISSUE WILL BE LAKE EFFECT PRECIPITATION. GYY LOOKS TO BE
IN LINE FOR LAKE EFFECT RAIN/SNOW AND POSSIBLY PERIODS OF ALL SNOW
FROM LATE MORNING INTO THE EVENING. THUNDER IS ALSO POSSIBLE AS
CONDITIONS BECOME QUITE UNSTABLE OVER THE LAKE. MAY NEED TO
INDICATE SUB 1SM VSBY IN MODERATE/HEAVY PRECIPITATION AS DETAILS
BECOME MORE CLEAR. GYY WILL ALSO LIKELY SEE THE STRONGEST WINDS
GIVEN THEIR PROXIMITY TO THE LAKE AND 45+ KT WILL BE POSSIBLE.

WINDS GRADUALLY EASE EARLY THIS EVENING AND LAKE EFFECT MAY BEGIN
TO TRANSITION WESTWARD INTO THE EARLY OVERNIGHT SO MDW AND
POSSIBLY ORD COULD BE IN LINE FOR SOME SNOW SHOWERS BUT CONDITIONS
WILL BECOME LESS FAVORABLE WITH TIME INTO SATURDAY MORNING. WILL
CONTINUE WITH SNOW SHOWER MENTION AT MDW THIS EVENING BUT LEAVE
ORD DRY FOR NOW.

MDB


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

* HIGH CONFIDENCE IN PRECIP TRENDS THROUGH THE MORNING.

* MEDIUM CONFIDENCE IN SOME SNOW SHOWERS THIS MORNING...LOW
  CONFIDENCE IN DURATION/INTENSITY.

* HIGH CONFIDENCE IN NORTHWEST WINDS TURNING NORTH AND IN GUSTS
  REACHING 35-37 KT...MEDIUM CONFIDENCE THAT SOME 40 KT GUSTS WILL
  OCCUR BUT LOW CONFIDENCE IN FREQUENCY AND BEST TIMING.

* MEDIUM-HIGH CONFIDENCE IN PERIODIC MVFR CIGS OVERNIGHT THROUGH
  THE MORNING.

* LOW CONFIDENCE IN LAKE EFFECT SNOW SHOWER POTENTIAL THIS
  EVENING.

MDB

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

* SATURDAY...DRY/VFR. NORTHEAST WINDS 10-15 KT.
* SUNDAY...DRY/VFR. SOUTH WINDS 10-15 KT.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.
* TUESDAY...SHRA/MVFR LIKELY. SOUTHWEST WINDS.
* WEDNESDAY...DRY/VFR. SOUTHWEST WINDS.

&&

.MARINE...
250 PM CDT

A VERY ACTIVE PERIOD OVER LAKE MICHIGAN BEGINNING LATER TONIGHT. THE
AREA WILL FIND ITSELF IN A FAVORABLE AND ANOMALOUS SYNOPTIC WEATHER
PATTERN FOR STRONG NORTHERLY WINDS...AND THIS WILL BE FURTHER AIDED
BY THE WARM WATERS/EXTREME INSTABILITY TO PRODUCE REGULAR HIGHER END
STORM FORCE GUSTS PERSISTING INTO FRIDAY. A STRONG COLD FRONT WILL
MOVE DOWN THE LAKE RAPIDLY FROM AROUND MIDNIGHT THROUGH 5 AM.
IMMEDIATELY BEHIND THIS A VERY TIGHT PRESSURE GRADIENT IN SYNC WITH
COLD AIR ADVECTION WILL PRODUCE A RAMP UP IN NORTHERLY WIND SPEEDS.
THE HIGHEST WIND SPEEDS OF STORM FORCE TO 50 AND POSSIBLY EVEN 55 KT
ARE EXPECTED LATE TONIGHT THROUGH MID FRIDAY AFTERNOON FOR THE
CENTRAL AND SOUTHERN PART OF THE LAKE...AND AFTER DAYBREAK THROUGH
THE DAY ON FRIDAY FOR THE NEARSHORE AREAS OF ILLINOIS AND INDIANA.
THE WAVE MAXIMUM OF OVER 20 FOOTERS IS EXPECTED TO DEVELOP OVER THE
CENTRAL PART OF THE LAKE EARLY FRIDAY MORNING AND EVOLVE SOUTHWARD
REACHING THE ILLINOIS AND INDIANA NEARSHORE FRIDAY AFTERNOON AND
EARLY EVENING. WAVES WILL BE VERY SLOW TO SUBSIDE THROUGH LATE
FRIDAY NIGHT AND EARLY SATURDAY. HIGH PRESSURE WILL MOVE QUICKLY
OVER THE LAKE SATURDAY NIGHT BEFORE SOUTHERLY FLOW RETURNS TO THE
LAKE.

MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WIND ADVISORY...ILZ014...7 AM FRIDAY TO 10 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022...7 AM
     FRIDAY TO 7 PM FRIDAY.

     WIND ADVISORY...ILZ023-ILZ033...10 AM FRIDAY TO 7 PM FRIDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011...10 AM
     FRIDAY TO 10 PM FRIDAY.

     WIND ADVISORY...INZ019...10 AM FRIDAY TO 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 PM FRIDAY TO
     4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
     LMZ878 UNTIL 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563 UNTIL 10 PM FRIDAY.

     GALE WARNING...LMZ740...4 AM FRIDAY TO 4 AM SATURDAY.

     STORM WARNING...LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...4 AM FRIDAY
     TO 7 PM FRIDAY.

&&

$$

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

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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000
FXUS63 KILX 310406
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1106 PM CDT Thu Oct 30 2014

.UPDATE...
ISSUED AT 830 PM CDT THU OCT 30 2014

Initial shortwave pushing across west central Illinois has brought
about some scattered showers this evening over most of our area.
A second and more potent upper wave seen on the water vapor loop
streaming south over the upper Great Lakes and that feature will
deepen in over the lower lakes tomorrow morning ushering much
colder air and strong northerly winds to the region. First band
of rain will shift into eastern and southeast Illinois this
evening with a second band of rain forecast to shift southeast
into our area along the quick moving cold front after midnight. 3
hourly pressure rises of 4 to 6 mb streaking southeast along the
cold front to our northwest and as the upper feature deepens in
over the lower lakes region, we should see some rather significant
pres rises develop just to our north and west which should bring
in the strong winds around sunrise across the north and during the
morning to the south.

Will continue to hold on to the POPs over most of the area until
that second wave tracks thru the area by Friday morning, with rain
chances then confined to far east and southeast Illinois. RAP and
HRRR indicating the potential for gusts of 40 to 45 mph tomorrow
morning into the afternoon hours across most of the area coupled
with steady or slowly falling temperatures. Wind chill readings
for the trick or treaters will be in the upper 20s to lower 30s
tomorrow evening!

Have already sent out an updated ZFP to address the more widespread
nature of the precip earlier in the evening and will have another
update out by 900 pm to adjust the late evening wording.

&&

.SHORT TERM...(Tonight)
ISSUED AT 300 PM CDT THU OCT 30 2014

Two waves impacting the short term.  The first low is over western
Missouri and weak lift associated with weak frontogenesis sparking
some showers for the region.  Plenty of dry air in the area is also
helping to erode the showers and keep them more scattered in
nature.  Cooler air on the way, with another shot of cold air
deepening the trof aloft with the next wave later this evening.
This second wave acting a bit more like a cold front with the wind
shift to more north/northwesterly winds tonight and cold air, but
the models are having a hard time with precip.  Current precip is
overblown in the models, and the later wave (after midnight) is even
more sketchy with QPF.  As a result, pops are minimal in association
with the second wave...and instead follow the progression of the
current precip out to the east by midnight. Temps currently on the
cooler side of guidance as the temps have not dropped far enough in
the last 24 hours and that trend may continue, though the RH will be
plenty for clouds, if not for ongoing precip. Tightening pressure
gradient behind the boundary resulting in winds ramping up in the
early morning hours in advance of a blustery cold day.

&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 300 PM CDT THU OCT 30 2014

A vigorous cold Canadian shortwave will drop southward into the
Midwest by Friday morning. A strong cold front with this feature
will usher in much colder air to central Illinois for Friday, with
highs only reaching the 40s. North-northwest winds 20-30 mph with
gusts 35-40 mph will develop along and behind the cold front,
bringing wind chills into the 30s for the afternoon. Little
precipitation will remain behind the front, however slight chances
will remain near the IL/IN border. Forecast soundings in this area
indicate wet bulb temperatures below freezing to ground level below
the precipitation generation level, and this should allow for light
snow or mixed rain and snow reaching the ground Friday afternoon and
evening. Breezy and cold conditions will continue into the evening
for Halloween Trick or Treat conditions with temperatures dropping
quickly into the 30s and wind chill values into the 20s.

Friday night, light north winds will continue, while the cold air
mass results in temperatures reaching 25-30 degrees for the first
widespread freeze of the season. Have issued a freeze warning to
account for this.

Little warming is expected through Sunday morning, with another
freezing night expected. A mild and moist southwesterly low level
flow will develop late in the weekend through early next week as an
upper level ridge shifts eastward across Illinois and a deep trough
crosses the Rockies. This trough will bring good chances of showers
late Monday through tuesday night as the system moves into the Ohio
river valley. Isolated thunderstorms may also occur Monday night and
Tue south of I-72. Drier weather is expected Wed night and Thu as
dry northwesterly flow trails the system.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 1105 PM CDT THU OCT 30 2014

VFR conditions will give way to a brief period of MVFR cigs in the
08z-12z time frame as a strong cold front tracks across the area.
Once the front shifts thru the area, strong northerly winds are
expected thru much of the day Friday with sustained winds of 20 to
30 kts with a few gusts around 35 kts at times. With the fropa, we
may see some scattered rain showers with the cigs lowering to
MVFR and a low probability for a brief period of IFR cigs with
any bands of rain that persist. Satellite data indicating cigs
around 2500 to 3500 feet north of the cold front over parts of
northern Iowa into central Wisconsin. Latest HRRR forecast indicates
the stratocumulus should begin to decrease in coverage and affect
mainly areas east of I55 by afternoon as subsidence develops in the
wake of the upper level shortwave. Surface winds will gradually
diminish, especially the gusts, towards evening with sustained winds
of 10 kts or less after 02z.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING from Midnight Friday Night to 9 AM CDT Saturday
FOR ILZ027>031-036>038-040>057-061>063-066>068-071>073.

&&

$$

UPDATE...Smith
SHORT TERM...HJS
LONG TERM...Onton
AVIATION...Smith





000
FXUS63 KILX 310406
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1106 PM CDT Thu Oct 30 2014

.UPDATE...
ISSUED AT 830 PM CDT THU OCT 30 2014

Initial shortwave pushing across west central Illinois has brought
about some scattered showers this evening over most of our area.
A second and more potent upper wave seen on the water vapor loop
streaming south over the upper Great Lakes and that feature will
deepen in over the lower lakes tomorrow morning ushering much
colder air and strong northerly winds to the region. First band
of rain will shift into eastern and southeast Illinois this
evening with a second band of rain forecast to shift southeast
into our area along the quick moving cold front after midnight. 3
hourly pressure rises of 4 to 6 mb streaking southeast along the
cold front to our northwest and as the upper feature deepens in
over the lower lakes region, we should see some rather significant
pres rises develop just to our north and west which should bring
in the strong winds around sunrise across the north and during the
morning to the south.

Will continue to hold on to the POPs over most of the area until
that second wave tracks thru the area by Friday morning, with rain
chances then confined to far east and southeast Illinois. RAP and
HRRR indicating the potential for gusts of 40 to 45 mph tomorrow
morning into the afternoon hours across most of the area coupled
with steady or slowly falling temperatures. Wind chill readings
for the trick or treaters will be in the upper 20s to lower 30s
tomorrow evening!

Have already sent out an updated ZFP to address the more widespread
nature of the precip earlier in the evening and will have another
update out by 900 pm to adjust the late evening wording.

&&

.SHORT TERM...(Tonight)
ISSUED AT 300 PM CDT THU OCT 30 2014

Two waves impacting the short term.  The first low is over western
Missouri and weak lift associated with weak frontogenesis sparking
some showers for the region.  Plenty of dry air in the area is also
helping to erode the showers and keep them more scattered in
nature.  Cooler air on the way, with another shot of cold air
deepening the trof aloft with the next wave later this evening.
This second wave acting a bit more like a cold front with the wind
shift to more north/northwesterly winds tonight and cold air, but
the models are having a hard time with precip.  Current precip is
overblown in the models, and the later wave (after midnight) is even
more sketchy with QPF.  As a result, pops are minimal in association
with the second wave...and instead follow the progression of the
current precip out to the east by midnight. Temps currently on the
cooler side of guidance as the temps have not dropped far enough in
the last 24 hours and that trend may continue, though the RH will be
plenty for clouds, if not for ongoing precip. Tightening pressure
gradient behind the boundary resulting in winds ramping up in the
early morning hours in advance of a blustery cold day.

&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 300 PM CDT THU OCT 30 2014

A vigorous cold Canadian shortwave will drop southward into the
Midwest by Friday morning. A strong cold front with this feature
will usher in much colder air to central Illinois for Friday, with
highs only reaching the 40s. North-northwest winds 20-30 mph with
gusts 35-40 mph will develop along and behind the cold front,
bringing wind chills into the 30s for the afternoon. Little
precipitation will remain behind the front, however slight chances
will remain near the IL/IN border. Forecast soundings in this area
indicate wet bulb temperatures below freezing to ground level below
the precipitation generation level, and this should allow for light
snow or mixed rain and snow reaching the ground Friday afternoon and
evening. Breezy and cold conditions will continue into the evening
for Halloween Trick or Treat conditions with temperatures dropping
quickly into the 30s and wind chill values into the 20s.

Friday night, light north winds will continue, while the cold air
mass results in temperatures reaching 25-30 degrees for the first
widespread freeze of the season. Have issued a freeze warning to
account for this.

Little warming is expected through Sunday morning, with another
freezing night expected. A mild and moist southwesterly low level
flow will develop late in the weekend through early next week as an
upper level ridge shifts eastward across Illinois and a deep trough
crosses the Rockies. This trough will bring good chances of showers
late Monday through tuesday night as the system moves into the Ohio
river valley. Isolated thunderstorms may also occur Monday night and
Tue south of I-72. Drier weather is expected Wed night and Thu as
dry northwesterly flow trails the system.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 1105 PM CDT THU OCT 30 2014

VFR conditions will give way to a brief period of MVFR cigs in the
08z-12z time frame as a strong cold front tracks across the area.
Once the front shifts thru the area, strong northerly winds are
expected thru much of the day Friday with sustained winds of 20 to
30 kts with a few gusts around 35 kts at times. With the fropa, we
may see some scattered rain showers with the cigs lowering to
MVFR and a low probability for a brief period of IFR cigs with
any bands of rain that persist. Satellite data indicating cigs
around 2500 to 3500 feet north of the cold front over parts of
northern Iowa into central Wisconsin. Latest HRRR forecast indicates
the stratocumulus should begin to decrease in coverage and affect
mainly areas east of I55 by afternoon as subsidence develops in the
wake of the upper level shortwave. Surface winds will gradually
diminish, especially the gusts, towards evening with sustained winds
of 10 kts or less after 02z.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING from Midnight Friday Night to 9 AM CDT Saturday
FOR ILZ027>031-036>038-040>057-061>063-066>068-071>073.

&&

$$

UPDATE...Smith
SHORT TERM...HJS
LONG TERM...Onton
AVIATION...Smith





000
FXUS63 KLOT 310304
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1004 PM CDT THU OCT 30 2014

.UPDATE...
921 PM

MID-EVENING UPDATE...

HAVE MADE SOME ADDITIONAL MINOR REFINEMENTS TO POPS FOR SHOWERS WITH
APPROACHING COLD FRONT TONIGHT. MORE IMPORTANTLY...HAVE BUMPED QPF
AND SNOWFALL AMOUNTS ASSOCIATED WITH LAKE EFFECT PRECIPITATION
EXPECTED FRIDAY AFTERNOON AND EVENING IN NORTHWEST INDIANA.

COLD FRONT CONTINUES TO DEVELOP SOUTHEASTWARD ACROSS IOWA...
MINNESOTA AND SOUTHWEST WISCONSIN THIS EVENING...AS COLD CANADIAN
HIGH PRESSURE EXPANDS SOUTHEAST TOWARD THE REGION. GUSTY WINDS STILL
REMAIN A FEW HOURS AWAY FOR THE LOCAL FORECAST AREA WITH
STRENGTHENING GUSTS MORE SHARPLY FALLING TEMPERATURES AFTER
MIDNIGHT. GENERALLY WEAK RADAR ECHOES NOTED ACROSS THE REGION AS
COLD ADVECTION AND LOW-LEVEL FRONTOGENESIS STRENGTHENS UPSTREAM OF
THE CWA. HIGH-RES GUIDANCE CONTINUES TO DEPICT DEVELOPMENT OF
SCATTERED LIGHT SHOWERS/SPRINKLES AFTER MIDNIGHT AS THE COLDER AIR
SPREADS IN...AND HAVE LARGELY BASED HOURLY POP TRENDS ALONG THESE
TRENDS.

ALL HEADLINES REMAIN UNCHANGED THROUGH THE PERIOD...WITH NO CHANGES
IN EXPECTATIONS OF THE VERY GUSTY WINDS...AND THE RESULTING LARGE
WAVES AND LAKESHORE FLOOD POTENTIAL ALONG LAKE MICHIGAN. BECOMING A
BIT MORE CONCERNED ABOUT POTENTIAL FOR SIGNIFICANT LAKE EFFECT SNOW
OVER NORTHWEST INDIANA FRIDAY AFTERNOON/EVENING...AND EVEN PORTIONS
OF THE IL LAKE SHORE AREAS FRIDAY NIGHT. REALLY IMPRESSIVE
THERMODYNAMIC SET-UP WITH COLD AIR OVER WARM LAKE WATERS AND STRONG
UNIDIRECTIONAL NORTHERLY FETCH OVER THE LAKE. ALLOWING FOR LAKE
SURFACE TEMPS IN THE LOW 50S F...LAKE-850 HPA DELTA T APPROACHES 20
DEG C DURING THE PERIOD AND YIELDS LAKE-INDUCED FORECAST CAPES UP TO
1200 J/KG AND INVERSION LEVELS ABOVE 15 KFT. THE ONLY POTENTIAL
LIMITING FACTOR...AND ITEM OF GREAT UNCERTAINTY...IS THE WARMTH OF
THE WATER/SURFACE WET BULB TEMPS SUPPLIED BY THE LONG FETCH OVER
WARM WATERS. GIVEN STRONG INSTABILITY...WITH GOOD LIKELIHOOD OF
THUNDER...THERMODYNAMIC INSTABILITY MAY WELL BE ABLE TO OVERCOME
WARM LOW LEVELS AND PRODUCE ACCUMULATING WET SNOWFALL. WITH MUCH
UNCERTAINTY REMAINING...HAVE INCREASED QPF/SNOWFALL AMOUNTS SLIGHTLY
ACROSS NORTHWEST INDIANA FRI AFTERNOON/NIGHT TO THE 1-3 INCH
RANGE...AND HAVE INDICATED THE POTENTIAL FOR LOCALLY HIGHER AMOUNTS
IN THE ADVISORY WSW TEXT. IF COLUMN IS ABLE TO COOL SUFFICIENTLY FOR
LONG DURATION +SN/TSSN...COULD BE SEVERAL INCHES MORE IN SOME SPOTS.
IN ADDITION...THOUGH INSTABILITY WEAKENS LATER FRIDAY NIGHT AS WINDS
SHIFT NORTHEAST...EXPECT LESS INTENSE RAIN/SNOW OR ALL SNOW SHOWERS
TO IMPINGE UPON PARTS OF THE ILLINOIS SHORE AND STATELINE AREAS AS
WELL.

RATZER

&&

.SHORT TERM...(TONIGHT THROUGH SATURDAY)
332 PM CDT...

THE MAIN FORECAST FOCUS THIS AFTERNOON CONTINUES TO CENTER AROUND
THE STORM SYSTEM EXPECTED IMPACT THE REGION LATE TONIGHT THROUGH
FRIDAY NIGHT. STRONG WINDS...AND THE POTENTIAL FOR SOME PERIODS OF
HEAVY LAKE EFFECT SNOW ARE THE PRIMARY CONCERNS.

WE ARE ISSUING A WIND ADVISORY FOR MOST OF THE EASTERN HALF OF THE
AREA...WITH THE EXCEPTION OF LAKE...PORTER...JASPER AND NEWTON
COUNTIES IN INDIANA...WHERE A WINTER WEATHER ADVISORY IS BEING
ISSUED. SEE BELOW FOR MORE DETAILS.

WATER VAPOR IMAGERY EARLY THIS AFTERNOON SHOWS A RATHER VIGOROUS
UPPER LEVEL IMPULSE NOW MOVING JUST EAST OF LAKE WINNIPEG AND OVER
FAR SOUTHWESTERN ONTARIO. THIS WAVE IS EXPECTED TO CONTINUE DIGGING
SOUTH-SOUTHEASTWARD TONIGHT ALONG THE EASTERN PERIPHERY OF AN UPPER
RIDGE...CURRENT CENTERED ACROSS THE INTER MOUNTAIN WEST. AS THIS
OCCURS...AN AREA OF SURFACE LOW PRESSURE WILL SHIFT SOUTHWARD ACROSS
LOWER MICHIGAN INTO FRIDAY MORNING. FARTHER NORTHWEST...A RATHER
STOUT 1036 MB HIGH IS ALSO EXPECTED TO RAPIDLY BUILD SOUTHEASTWARD
ACROSS THE DAKOTAS AND UPPER MIDWEST INTO FRIDAY. THIS STILL LOOKS
TO SET THE STAGE FOR STRONG NORTHERN WINDS ACROSS THE AREA DURING
THE DAY FRIDAY AS STRONG PRESSURE RISES AND STRONG COLD AIR
ADVECTION LEAD TO A QUICK RAMP UP OF NORTHERLY WINDS IN THE WAKE OF
A COLD FRONTAL PASSAGE LATE TONIGHT. MODEL SOUNDINGS ALL SUGGEST
MEAN MIXING LAYER WIND SPEEDS COULD TOP 40 KT ACROSS MAINLY THE
EASTERN HALF OF THE AREA INLAND FROM THE LAKE...MEANING WIND GUSTS
COULD EASILY REACH THIS MAGNITUDE IN MOST AREAS. HOWEVER...AREAS
DIRECTLY ADJACENT TO LAKE MICHIGAN IN NORTHEASTERN ILLINOIS AND
NORTHWESTERN INDIANA COULD EXPERIENCE EVEN STRONGER GUSTS UP AROUND
50 KT WITH THE STRONG NORTHERLY ONSHORE COMPONENT TO THE WINDS.
WINDS LOOK TO REMAIN INTO THE EVENING ON HALLOWEEN...THOUGH WIND
SPEEDS SHOULD GRADUALLY WEAKEN THROUGH THE NIGHT.

THE LAKE SHORE FLOOD ADVISORY WILL CONTINUE FOR AREAS NEAR THE LAKE
AS LARGE BATTERING WAVES IN EXCESS OF 20 FT APPEAR LIKELY...AND AS
THE PREVIOUS DISCUSSION MENTIONED...LAKE LEVELS ARE ABOUT 2 FT
HIGHER THAN PAST YEARS...WHICH COULD MAKE THE IMPACTS OF THESE WAVES
HIGHER THEN SIMILAR WAVE EVENTS IN THE PAST COUPLE OF YEARS.

DUE TO THE LIKELIHOOD OF THESE STRONG WINDS...WE HAVE ISSUED A WIND
ADVISORY FOR MUCH OF THE EASTERN HALF OF MY CWA. THIS
INCLUDES AREAS BASICALLY ALONG AND EAST OF A LINE FROM HARVARD
SOUTHWARD THROUGH KANKAKEE AND IROQUOIS COUNTIES. THE ONLY EXCEPTION
TO THIS WIND ADVISORY IS FOR LAKE COUNTY INDIANA...AS WELL AS
PORTER...JASPER AND NEWTON COUNTIES...WHERE A WINTER WEATHER
ADVISORY IS BEING ISSUED IN PLACE OF A WIND ADVISORY FOR THE
COMBINATION OF THESE STRONG WINDS AND ALSO THE INCREASING POTENTIAL
FOR SOME ACCUMULATING LAKE EFFECT SNOW ON FRIDAY INTO FRIDAY
EVENING.

PRECIPITATION WITH THE APPROACHING COLD FRONT AND UPPER LEVEL
IMPULSE
WILL LIKELY BEGIN TO ENTER FAR NORTHERN ILLINOIS AFTER 10 PM THIS
EVENING...AND BE IN THE FORM OF RAIN SHOWERS. THIS INITIAL ROUND OF
SHOWERS SHOULD MOVE SOUTHWARD ACROSS THE AREA THROUGH THE NIGHT...IN
CLOSE PROXIMITY THE INCREASING FRONTOGENESIS IN THE VICINITY OF THE
COLD FRONTAL BOUNDARY. THIS SHOULD BE A FAIRLY PROGRESSIVE AREA OF
SHOWERS...WITH MOST AREAS ACROSS NORTH CENTRAL ILLINOIS DRYING OUT
BY EARLY FRIDAY MORNING.

THE SECOND STAGE OF PRECIPITATION WILL BE MORE OF A TRUE LAKE EFFECT
SETUP. A COLD AIRMASS FEATURING -7 DEGREE C TEMPERATURES AT 850 MB
WILL MOVE OVER THE LAKE...WHICH IS CURRENTLY REPORTING A 53F (11.7C)
DEGREE WATER TEMPERATURE AT THE SOUTH BUOY. THEREFORE...DELTA T`S
SHOULD END UP VERY FAVORABLE AROUND 19 DEGREES C. IN ADDITION...DEEP
LAKE INDUCED INSTABILITY IS STILL EXPECTED...WITH EQUILIBRIUM LEVELS
LIKELY TO REACH OR EVEN EXCEED 16,000 FT AGL. THEREFORE...THE THREAT
FOR THUNDER AND LIGHTNING HAS NOT CHANGED...WITH CONVECTIVE
PROCESSES
LIKELY TO BE MORE THAN DEEP ENOUGH THROUGH THE -10 TO -20 LAYER TO
RESULT IN GOOD CHARGE SEPARATION.

IT LOOKS AS THOUGH THIS LAKE EFFECT BAND COULD BEGIN TO SET UP
ACROSS NORTHWESTERN INDIANA AND PERHAPS PORTIONS OF SOUTHEASTERN
COOK COUNTY BY LATE FRIDAY MORNING. HI RES GUIDANCE SUGGESTS
UNCERTAINTY ON THE EXACT AREAS THAT WILL GET THIS LAKE EFFECT
BANDING. SOME HAVE HINTED IN A FARTHER WEST BAND...WHICH WOULD
IMPACT MORE OF THE CHICAGO AREA. HOWEVER...I THINK AT THIS POINT
AREAS IN NORTHWEST INDIANA WILL BE MORE FAVORED...WITH THE
LIKELIHOOD OF A NEARLY DUE NORTH BOUNDARY LAYER FLOW SETTING UP OVER
LAKE MICHIGAN. THIS WOULD TEND TO FAVOR BETTER BOUNDARY LAYER
CONVERGENCE ALONG THE SOUTHERN TIP OF LAKE MICHIGAN FRIDAY
AFTERNOON...WHICH SUGGESTS THAT PORTER AND LAKE INDIANA WILL BE MORE
IN LINE WITH THE POTENTIAL HEAVIER PRECIPITATION. DUE TO THE STRONG
WINDS...IT IS ALSO LIKELY THAT THIS LAKE EFFECT PRECIP COULD BE
DRIVEN WELL INLAND ACROSS NORTHWESTERN INDIANA...POSSIBLY IMPACTING
MUCH OF JASPER AND PORTER COUNTIES AS WELL.

UNCERTAINTY IN PRECIPITATION TYPE IS STILL SOMEWHAT HIGH...AS
SOME WARMER AIR MOVING OFF THE LAKE SHOULD MAKE BOUNDARY LAYER
TEMPERATURES MARGINAL FOR SNOW TO REACH THE SURFACE. HOWEVER...WITH
THE AFOREMENTIONED CONVECTIVE INSTABILITY AND THE GOOD POTENTIAL FOR
SOME HEAVIER PRECIP RATES...IT IS VERY MUCH IN THE REALM OF
POSSIBILITIES THAT ENHANCED DYNAMIC COOLING COULD RESULT IN A COLD
ENOUGH BOUNDARY LAYER SUPPORTIVE OF HEAVY SNOW. IT APPEARS THAT
AREAS INLAND FROM THE IMMEDIATE LAKE SHORE WOULD HAVE THE BEST
POTENTIAL FOR SNOW...THOUGH EVEN AREAS ALONG THE LAKE COULD CHANGE
OVER/MIX WITH SNOW. OVERALL...WITH THE POTENTIAL FOR SOME HEAVIER
BANDS OF SNOW WITH SOME ACCUMULATIONS POSSIBLE (POSSIBLY A FEW
INCHES IN SOME AREAS) ALONG WITH THE VERY STRONG NORTHERLY
WINDS...WE HAVE CHOSEN TO ISSUE THE WINTER WEATHER ADVISORY FOR THE
4 NORTHWESTERN INDIANA COUNTIES. IF...HOWEVER...THE TRANSITION TO
SNOW DOES NOT PAN OUT AS CURRENT THINKING SUGGESTS...WINDS WOULD BE
THE MAIN HAZARD ON FRIDAY...AND THE WINTER WEATHER ADVISORY COULD
THEN BE REPLACED WITH A WIND ADVISORY. THEREFORE...IN SPITE OF THE
UNCERTAINTIES ON WHEN CHANGE OVERS TO SNOW WILL OCCUR AND HOW MUCH
SNOW WILL ACTUALLY FALL...WE FEEL AT THIS POINT...TO ERROR ON THE
SIDE OF CAUTION...AS THERE IS A POTENTIAL FOR SOME VERY HEAVY SNOW
IN ADDITION TO THE STRONG WINDS.

THE WINDS ARE EXPECTED TO GRADUALLY VEER MORE NORTHEASTERLY FRIDAY
NIGHT...AND THIS COULD ALLOW SOME OF THE LAKE EFFECT PRECIPITATION
TO GET INTO NORTHEASTERN ILLINOIS FOR A BRIEF PERIOD FRIDAY EVENING.
HOWEVER...MODEL GUIDANCE CONTINUES TO SUGGEST THAT INVERSION HEIGHTS
WILL CRASH IN A HURRY BY LATE FRIDAY EVENING AS HEIGHTS AND
TEMPERATURES BEGIN TO RISE ALOFT. THEREFORE...ANY SNOW SHOWERS THAT
GET INTO NORTHEASTERN ILLINOIS WOULD LIKELY BE LIGHT AND COME TO AN
END LATE FRIDAY NIGHT/EARLY SAT MORNING.

HIGH TEMPERATURES AREA-WIDE LOOK TO REMAIN IN THE LOWER 40S AT BEST
ON FRIDAY AND SATURDAY

KJB

&&

.LONG TERM...

HIGH TEMPERATURES WILL MODERATE INTO EARLY NEXT WEEK AS THE
WESTERN CONUS UPPER RIDGE BUILDS EASTWARD OVER THE REGION. ANOTHER
COLD FRONT LOOKS TO TAKE AIM ON THE AREA AROUND NEXT
TUESDAY...WHICH WILL RESULT IN OUR NEXT CHANCE OF SHOWERS.
OTHERWISE TEMPERATURES LOOK TO REMAIN NEAR NORMAL DURING THE LATER
HALF OF THE WEEK.

KJB

&&

.AVIATION...

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

* RAIN SHOWERS OVERNIGHT.
* SNOW SHOWERS FRIDAY MORNING AND POSSIBLY LATE FRIDAY AFTERNOON.
* MVFR CIGS OVERNIGHT THRU FRIDAY MORNING.
* STRONG/GUSTY NORTHWEST WINDS OVERNIGHT.
* VERY STRONG/GUSTY NORTHERLY WINDS TO 40 KT FRIDAY. CMS

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

MULTIPLE FORECAST CONCERNS THIS PERIOD. LOW PRESSURE OVER THE
EASTERN U.P. WILL MOVE TO LAKE HURON BY MORNING. A TRAILING COLD
FRONT WILL MOVE ACROSS THE AREA LATE THIS EVENING INTO THE EARLY
MORNING HOURS...SHIFTING WESTERLY WINDS TO THE NORTHWEST WITH
SPEEDS SLOWLY INCREASING. AS COLDER AIR SPREADS ACROSS THE AREA
LATE THIS EVENING AND OVERNIGHT...RAIN SHOWERS ARE EXPECTED TO
DEVELOP...MOSTLY LIKELY RIGHT OVER THE TERMINALS. THERMAL PROFILES
SUGGEST PRECIP SHOULD REMAIN MAINLY RAIN THRU MUCH OF THE NIGHT
AND PERHAPS ONLY LAST A FEW HOURS THOUGH CONFIDENCE ON TIMING IS
LOW ENOUGH TO MAINTAIN VICINITY MENTION.

WINDS CONTINUE TO INCREASE FRIDAY MORNING AS COLDER AIR CONTINUES
TO POUR INTO THE REGION. AS WINDS SHIFT TO THE NORTH MID/LATE
MORNING...THERE WILL BE ANOTHER CHANCE FOR PRECIPITATION...BY THIS
TIME...THERMAL PROFILES ARE COLD ENOUGH FOR AT LEAST A MIX OF RAIN
AND SNOW BUT MAINTAINED SNOW SHOWERS FROM PREVIOUS FORECAST.
CONFIDENCE REGARDING SPECIFICS DURING THIS TIME PERIOD ARE LOW...
INCLUDING DURATION AND INTENSITY. AS THIS TIME PERIOD APPROACHES
AND TRENDS EMERGE ON RADAR...A SHORT DURATION TEMPO FOR LOWER
CONDITIONS MAY BE NEEDED.

CIGS SHOULD REMAIN VFR THIS EVENING AND LOWER TO MVFR OVERNIGHT
WITH THE POTENTIAL FOR A SHORT PERIOD OF LOW MVFR POSSIBLE. ONCE
PRECIP ENDS IN THE MORNING...CIGS SHOULD LIFT TO EITHER HIGH MVFR
OR LOW VFR.

WINDS WILL STEADILY INCREASE FROM THE EARLY MORNING THRU THE LATE
MORNING AND TURN NORTHERLY. PREVAILING SPEEDS IN THE MID 20 KT
RANGE LOOK ON TRACK WITH PREVAILING GUSTS INTO THE MID/UPPER 30KT
RANGE WITH THE POTENTIAL FOR GUSTS TO 40KTS IN THE LATE MORNING
AND EARLY AFTERNOON. SPEEDS/GUSTS WILL SLOWLY DIMINISH LATE IN THE
AFTERNOON...ESPECIALLY AT RFD...BUT WINDY CONDITIONS WILL CONTINUE
INTO FRIDAY EVENING.

AS FOR GYY AND LAKE EFFECT...A BAND OF LAKE EFFECT RAIN AND SNOW
IS EXPECTED TO DEVELOP BY MID MORNING AND CONTINUE INTO FRIDAY
EVENING...AFFECTING NORTHWEST INDIANA FOR MUCH OF THE DAY. THIS
PRECIPITATION IS EXPECTED TO BE QUIET INTENSE WITH THUNDER LIKELY.
IF THIS INTENSE PRECIP IS SUFFICIENT ENOUGH TO COOL THE LOWER
LAYERS...THE PRECIP MAY SWITCH OVER TO ALL OR PREDOMINANTLY SNOW.
CONFIDENCE IN HOW LONG THIS MAY PERSIST IS LOW AND MAINTAINED A
RAIN/SNOW MIX AT GYY WITH A PERIOD OF REDUCED VIS/CIGS IN THE
EARLY/MID AFTERNOON. SPECIFICS ARE DIFFICULT FROM THIS DISTANCE
AND CHANGES TO THE GYY FORECAST SHOULD BE EXPECTED.

SOME OF THE GUIDANCE SHOWS THIS LAKE EFFECT PRECIPITATION MOVING
BACK WEST TOWARD ORD/MDW LATE FRIDAY AFTERNOON INTO FRIDAY
EVENING. CONFIDENCE REGARDING THIS TREND IS ALSO LOW. HOWEVER...
THE BAND WILL BE CLOSE ENOUGH TO MDW TO ADD MENTION LATE IN THE
AFTERNOON WITH THIS FORECAST. IF PRECIP IS SNOW AND DOES MAKE IT
TO ORD/MDW...IFR CIGS/VIS ARE CERTAINLY POSSIBLE. CMS

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

* HIGH FOR RAIN SHOWERS OVERNIGHT.
* MEDIUM FOR SNOW SHOWERS FRIDAY MORNING...LOW FOR DURATION/
  INTENSITY.
* LOW FOR SNOW SHOWERS LATE FRIDAY AFTERNOON.
* MEDIUM FOR MVFR CIGS OVERNIGHT/FRIDAY MORNING.
* HIGH FOR WIND SPEEDS/GUSTS/DIRECTION THRU THE PERIOD...MEDIUM
  FOR TIMING/CHANGES. CMS

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

* SATURDAY...DRY/VFR. NORTHEAST WINDS 10-15 KT.
* SUNDAY...DRY/VFR. SOUTH WINDS 10-15 KT.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.
* TUESDAY...SHRA/MVFR LIKELY. SOUTHWEST WINDS.
* WEDNESDAY...DRY/VFR. SOUTHWEST WINDS.

&&

.MARINE...
250 PM CDT

A VERY ACTIVE PERIOD OVER LAKE MICHIGAN BEGINNING LATER TONIGHT. THE
AREA WILL FIND ITSELF IN A FAVORABLE AND ANOMALOUS SYNOPTIC WEATHER
PATTERN FOR STRONG NORTHERLY WINDS...AND THIS WILL BE FURTHER AIDED
BY THE WARM WATERS/EXTREME INSTABILITY TO PRODUCE REGULAR HIGHER END
STORM FORCE GUSTS PERSISTING INTO FRIDAY. A STRONG COLD FRONT WILL
MOVE DOWN THE LAKE RAPIDLY FROM AROUND MIDNIGHT THROUGH 5 AM.
IMMEDIATELY BEHIND THIS A VERY TIGHT PRESSURE GRADIENT IN SYNC WITH
COLD AIR ADVECTION WILL PRODUCE A RAMP UP IN NORTHERLY WIND SPEEDS.
THE HIGHEST WIND SPEEDS OF STORM FORCE TO 50 AND POSSIBLY EVEN 55 KT
ARE EXPECTED LATE TONIGHT THROUGH MID FRIDAY AFTERNOON FOR THE
CENTRAL AND SOUTHERN PART OF THE LAKE...AND AFTER DAYBREAK THROUGH
THE DAY ON FRIDAY FOR THE NEARSHORE AREAS OF ILLINOIS AND INDIANA.
THE WAVE MAXIMUM OF OVER 20 FOOTERS IS EXPECTED TO DEVELOP OVER THE
CENTRAL PART OF THE LAKE EARLY FRIDAY MORNING AND EVOLVE SOUTHWARD
REACHING THE ILLINOIS AND INDIANA NEARSHORE FRIDAY AFTERNOON AND
EARLY EVENING. WAVES WILL BE VERY SLOW TO SUBSIDE THROUGH LATE
FRIDAY NIGHT AND EARLY SATURDAY. HIGH PRESSURE WILL MOVE QUICKLY
OVER THE LAKE SATURDAY NIGHT BEFORE SOUTHERLY FLOW RETURNS TO THE
LAKE.

MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WIND ADVISORY...ILZ014...7 AM FRIDAY TO 10 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022...7 AM
     FRIDAY TO 7 PM FRIDAY.

     WIND ADVISORY...ILZ023-ILZ033...10 AM FRIDAY TO 7 PM FRIDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011...10 AM
     FRIDAY TO 10 PM FRIDAY.

     WIND ADVISORY...INZ019...10 AM FRIDAY TO 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 PM FRIDAY TO
     4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
     LMZ878...3 AM FRIDAY TO 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563 UNTIL 10 PM FRIDAY.

     GALE WARNING...LMZ740...4 AM FRIDAY TO 4 AM SATURDAY.

     STORM WARNING...LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...4 AM FRIDAY
     TO 7 PM FRIDAY.

&&

$$

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

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






000
FXUS63 KLOT 310221
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
921 PM CDT THU OCT 30 2014

.DISCUSSION...

MID-EVENING UPDATE...

HAVE MADE SOME ADDITIONAL MINOR REFINEMENTS TO POPS FOR SHOWERS WITH
APPROACHING COLD FRONT TONIGHT. MORE IMPORTANTLY...HAVE BUMPED QPF
AND SNOWFALL AMOUNTS ASSOCIATED WITH LAKE EFFECT PRECIPITATION
EXPECTED FRIDAY AFTERNOON AND EVENING IN NORTHWEST INDIANA.

COLD FRONT CONTINUES TO DEVELOP SOUTHEASTWARD ACROSS IOWA...
MINNESOTA AND SOUTHWEST WISCONSIN THIS EVENING...AS COLD CANADIAN
HIGH PRESSURE EXPANDS SOUTHEAST TOWARD THE REGION. GUSTY WINDS STILL
REMAIN A FEW HOURS AWAY FOR THE LOCAL FORECAST AREA WITH
STRENGTHENING GUSTS MORE SHARPLY FALLING TEMPERATURES AFTER
MIDNIGHT. GENERALLY WEAK RADAR ECHOES NOTED ACROSS THE REGION AS
COLD ADVECTION AND LOW-LEVEL FRONTOGENESIS STRENGTHENS UPSTREAM OF
THE CWA. HIGH-RES GUIDANCE CONTINUES TO DEPICT DEVELOPMENT OF
SCATTERED LIGHT SHOWERS/SPRINKLES AFTER MIDNIGHT AS THE COLDER AIR
SPREADS IN...AND HAVE LARGELY BASED HOURLY POP TRENDS ALONG THESE
TRENDS.

ALL HEADLINES REMAIN UNCHANGED THROUGH THE PERIOD...WITH NO CHANGES
IN EXPECTATIONS OF THE VERY GUSTY WINDS...AND THE RESULTING LARGE
WAVES AND LAKESHORE FLOOD POTENTIAL ALONG LAKE MICHIGAN. BECOMING A
BIT MORE CONCERNED ABOUT POTENTIAL FOR SIGNIFICANT LAKE EFFECT SNOW
OVER NORTHWEST INDIANA FRIDAY AFTERNOON/EVENING...AND EVEN PORTIONS
OF THE IL LAKE SHORE AREAS FRIDAY NIGHT. REALLY IMPRESSIVE
THERMODYNAMIC SET-UP WITH COLD AIR OVER WARM LAKE WATERS AND STRONG
UNIDIRECTIONAL NORTHERLY FETCH OVER THE LAKE. ALLOWING FOR LAKE
SURFACE TEMPS IN THE LOW 50S F...LAKE-850 HPA DELTA T APPROACHES 20
DEG C DURING THE PERIOD AND YIELDS LAKE-INDUCED FORECAST CAPES UP TO
1200 J/KG AND INVERSION LEVELS ABOVE 15 KFT. THE ONLY POTENTIAL
LIMITING FACTOR...AND ITEM OF GREAT UNCERTAINTY...IS THE WARMTH OF
THE WATER/SURFACE WET BULB TEMPS SUPPLIED BY THE LONG FETCH OVER
WARM WATERS. GIVEN STRONG INSTABILITY...WITH GOOD LIKELIHOOD OF
THUNDER...THERMODYNAMIC INSTABILITY MAY WELL BE ABLE TO OVERCOME
WARM LOW LEVELS AND PRODUCE ACCUMULATING WET SNOWFALL. WITH MUCH
UNCERTAINTY REMAINING...HAVE INCREASED QPF/SNOWFALL AMOUNTS SLIGHTLY
ACROSS NORTHWEST INDIANA FRI AFTERNOON/NIGHT TO THE 1-3 INCH
RANGE...AND HAVE INDICATED THE POTENTIAL FOR LOCALLY HIGHER AMOUNTS
IN THE ADVISORY WSW TEXT. IF COLUMN IS ABLE TO COOL SUFFICIENTLY FOR
LONG DURATION +SN/TSSN...COULD BE SEVERAL INCHES MORE IN SOME SPOTS.
IN ADDITION...THOUGH INSTABILITY WEAKENS LATER FRIDAY NIGHT AS WINDS
SHIFT NORTHEAST...EXPECT LESS INTENSE RAIN/SNOW OR ALL SNOW SHOWERS
TO IMPINGE UPON PARTS OF THE ILLINOIS SHORE AND STATELINE AREAS AS
WELL.

RATZER

PREVIOUS DISCUSSION FROM 332 PM CDT...

SHORT TERM...TONIGHT THROUGH SATURDAY...
THE MAIN FORECAST FOCUS THIS AFTERNOON CONTINUES TO CENTER AROUND
THE STORM SYSTEM EXPECTED IMPACT THE REGION LATE TONIGHT THROUGH
FRIDAY NIGHT. STRONG WINDS...AND THE POTENTIAL FOR SOME PERIODS OF
HEAVY LAKE EFFECT SNOW ARE THE PRIMARY CONCERNS.

WE ARE ISSUING A WIND ADVISORY FOR MOST OF THE EASTERN HALF OF THE
AREA...WITH THE EXCEPTION OF LAKE...PORTER...JASPER AND NEWTON
COUNTIES IN INDIANA...WHERE A WINTER WEATHER ADVISORY IS BEING
ISSUED. SEE BELOW FOR MORE DETAILS.

WATER VAPOR IMAGERY EARLY THIS AFTERNOON SHOWS A RATHER VIGOROUS
UPPER LEVEL IMPULSE NOW MOVING JUST EAST OF LAKE WINNIPEG AND OVER
FAR SOUTHWESTERN ONTARIO. THIS WAVE IS EXPECTED TO CONTINUE DIGGING
SOUTH-SOUTHEASTWARD TONIGHT ALONG THE EASTERN PERIPHERY OF AN UPPER
RIDGE...CURRENT CENTERED ACROSS THE INTER MOUNTAIN WEST. AS THIS
OCCURS...AN AREA OF SURFACE LOW PRESSURE WILL SHIFT SOUTHWARD ACROSS
LOWER MICHIGAN INTO FRIDAY MORNING. FARTHER NORTHWEST...A RATHER
STOUT 1036 MB HIGH IS ALSO EXPECTED TO RAPIDLY BUILD SOUTHEASTWARD
ACROSS THE DAKOTAS AND UPPER MIDWEST INTO FRIDAY. THIS STILL LOOKS
TO SET THE STAGE FOR STRONG NORTHERN WINDS ACROSS THE AREA DURING
THE DAY FRIDAY AS STRONG PRESSURE RISES AND STRONG COLD AIR
ADVECTION LEAD TO A QUICK RAMP UP OF NORTHERLY WINDS IN THE WAKE OF
A COLD FRONTAL PASSAGE LATE TONIGHT. MODEL SOUNDINGS ALL SUGGEST
MEAN MIXING LAYER WIND SPEEDS COULD TOP 40 KT ACROSS MAINLY THE
EASTERN HALF OF THE AREA INLAND FROM THE LAKE...MEANING WIND GUSTS
COULD EASILY REACH THIS MAGNITUDE IN MOST AREAS. HOWEVER...AREAS
DIRECTLY ADJACENT TO LAKE MICHIGAN IN NORTHEASTERN ILLINOIS AND
NORTHWESTERN INDIANA COULD EXPERIENCE EVEN STRONGER GUSTS UP AROUND
50 KT WITH THE STRONG NORTHERLY ONSHORE COMPONENT TO THE WINDS.
WINDS LOOK TO REMAIN INTO THE EVENING ON HALLOWEEN...THOUGH WIND
SPEEDS SHOULD GRADUALLY WEAKEN THROUGH THE NIGHT.

THE LAKE SHORE FLOOD ADVISORY WILL CONTINUE FOR AREAS NEAR THE LAKE
AS LARGE BATTERING WAVES IN EXCESS OF 20 FT APPEAR LIKELY...AND AS
THE PREVIOUS DISCUSSION MENTIONED...LAKE LEVELS ARE ABOUT 2 FT
HIGHER THAN PAST YEARS...WHICH COULD MAKE THE IMPACTS OF THESE WAVES
HIGHER THEN SIMILAR WAVE EVENTS IN THE PAST COUPLE OF YEARS.

DUE TO THE LIKELIHOOD OF THESE STRONG WINDS...WE HAVE ISSUED A WIND
ADVISORY FOR MUCH OF THE EASTERN HALF OF MY CWA. THIS
INCLUDES AREAS BASICALLY ALONG AND EAST OF A LINE FROM HARVARD
SOUTHWARD THROUGH KANKAKEE AND IROQUOIS COUNTIES. THE ONLY EXCEPTION
TO THIS WIND ADVISORY IS FOR LAKE COUNTY INDIANA...AS WELL AS
PORTER...JASPER AND NEWTON COUNTIES...WHERE A WINTER WEATHER
ADVISORY IS BEING ISSUED IN PLACE OF A WIND ADVISORY FOR THE
COMBINATION OF THESE STRONG WINDS AND ALSO THE INCREASING POTENTIAL
FOR SOME ACCUMULATING LAKE EFFECT SNOW ON FRIDAY INTO FRIDAY
EVENING.

PRECIPITATION WITH THE APPROACHING COLD FRONT AND UPPER LEVEL
IMPULSE
WILL LIKELY BEGIN TO ENTER FAR NORTHERN ILLINOIS AFTER 10 PM THIS
EVENING...AND BE IN THE FORM OF RAIN SHOWERS. THIS INITIAL ROUND OF
SHOWERS SHOULD MOVE SOUTHWARD ACROSS THE AREA THROUGH THE NIGHT...IN
CLOSE PROXIMITY THE INCREASING FRONTOGENESIS IN THE VICINITY OF THE
COLD FRONTAL BOUNDARY. THIS SHOULD BE A FAIRLY PROGRESSIVE AREA OF
SHOWERS...WITH MOST AREAS ACROSS NORTH CENTRAL ILLINOIS DRYING OUT
BY EARLY FRIDAY MORNING.

THE SECOND STAGE OF PRECIPITATION WILL BE MORE OF A TRUE LAKE EFFECT
SETUP. A COLD AIRMASS FEATURING -7 DEGREE C TEMPERATURES AT 850 MB
WILL MOVE OVER THE LAKE...WHICH IS CURRENTLY REPORTING A 53F (11.7C)
DEGREE WATER TEMPERATURE AT THE SOUTH BUOY. THEREFORE...DELTA T`S
SHOULD END UP VERY FAVORABLE AROUND 19 DEGREES C. IN ADDITION...DEEP
LAKE INDUCED INSTABILITY IS STILL EXPECTED...WITH EQUILIBRIUM LEVELS
LIKELY TO REACH OR EVEN EXCEED 16,000 FT AGL. THEREFORE...THE THREAT
FOR THUNDER AND LIGHTNING HAS NOT CHANGED...WITH CONVECTIVE
PROCESSES
LIKELY TO BE MORE THAN DEEP ENOUGH THROUGH THE -10 TO -20 LAYER TO
RESULT IN GOOD CHARGE SEPARATION.

IT LOOKS AS THOUGH THIS LAKE EFFECT BAND COULD BEGIN TO SET UP
ACROSS NORTHWESTERN INDIANA AND PERHAPS PORTIONS OF SOUTHEASTERN
COOK COUNTY BY LATE FRIDAY MORNING. HI RES GUIDANCE SUGGESTS
UNCERTAINTY ON THE EXACT AREAS THAT WILL GET THIS LAKE EFFECT
BANDING. SOME HAVE HINTED IN A FARTHER WEST BAND...WHICH WOULD
IMPACT MORE OF THE CHICAGO AREA. HOWEVER...I THINK AT THIS POINT
AREAS IN NORTHWEST INDIANA WILL BE MORE FAVORED...WITH THE
LIKELIHOOD OF A NEARLY DUE NORTH BOUNDARY LAYER FLOW SETTING UP OVER
LAKE MICHIGAN. THIS WOULD TEND TO FAVOR BETTER BOUNDARY LAYER
CONVERGENCE ALONG THE SOUTHERN TIP OF LAKE MICHIGAN FRIDAY
AFTERNOON...WHICH SUGGESTS THAT PORTER AND LAKE INDIANA WILL BE MORE
IN LINE WITH THE POTENTIAL HEAVIER PRECIPITATION. DUE TO THE STRONG
WINDS...IT IS ALSO LIKELY THAT THIS LAKE EFFECT PRECIP COULD BE
DRIVEN WELL INLAND ACROSS NORTHWESTERN INDIANA...POSSIBLY IMPACTING
MUCH OF JASPER AND PORTER COUNTIES AS WELL.

UNCERTAINTY IN PRECIPITATION TYPE IS STILL SOMEWHAT HIGH...AS
SOME WARMER AIR MOVING OFF THE LAKE SHOULD MAKE BOUNDARY LAYER
TEMPERATURES MARGINAL FOR SNOW TO REACH THE SURFACE. HOWEVER...WITH
THE AFOREMENTIONED CONVECTIVE INSTABILITY AND THE GOOD POTENTIAL FOR
SOME HEAVIER PRECIP RATES...IT IS VERY MUCH IN THE REALM OF
POSSIBILITIES THAT ENHANCED DYNAMIC COOLING COULD RESULT IN A COLD
ENOUGH BOUNDARY LAYER SUPPORTIVE OF HEAVY SNOW. IT APPEARS THAT
AREAS INLAND FROM THE IMMEDIATE LAKE SHORE WOULD HAVE THE BEST
POTENTIAL FOR SNOW...THOUGH EVEN AREAS ALONG THE LAKE COULD CHANGE
OVER/MIX WITH SNOW. OVERALL...WITH THE POTENTIAL FOR SOME HEAVIER
BANDS OF SNOW WITH SOME ACCUMULATIONS POSSIBLE (POSSIBLY A FEW
INCHES IN SOME AREAS) ALONG WITH THE VERY STRONG NORTHERLY
WINDS...WE HAVE CHOSEN TO ISSUE THE WINTER WEATHER ADVISORY FOR THE
4 NORTHWESTERN INDIANA COUNTIES. IF...HOWEVER...THE TRANSITION TO
SNOW DOES NOT PAN OUT AS CURRENT THINKING SUGGESTS...WINDS WOULD BE
THE MAIN HAZARD ON FRIDAY...AND THE WINTER WEATHER ADVISORY COULD
THEN BE REPLACED WITH A WIND ADVISORY. THEREFORE...IN SPITE OF THE
UNCERTAINTIES ON WHEN CHANGE OVERS TO SNOW WILL OCCUR AND HOW MUCH
SNOW WILL ACTUALLY FALL...WE FEEL AT THIS POINT...TO ERROR ON THE
SIDE OF CAUTION...AS THERE IS A POTENTIAL FOR SOME VERY HEAVY SNOW
IN ADDITION TO THE STRONG WINDS.

THE WINDS ARE EXPECTED TO GRADUALLY VEER MORE NORTHEASTERLY FRIDAY
NIGHT...AND THIS COULD ALLOW SOME OF THE LAKE EFFECT PRECIPITATION
TO GET INTO NORTHEASTERN ILLINOIS FOR A BRIEF PERIOD FRIDAY EVENING.
HOWEVER...MODEL GUIDANCE CONTINUES TO SUGGEST THAT INVERSION HEIGHTS
WILL CRASH IN A HURRY BY LATE FRIDAY EVENING AS HEIGHTS AND
TEMPERATURES BEGIN TO RISE ALOFT. THEREFORE...ANY SNOW SHOWERS THAT
GET INTO NORTHEASTERN ILLINOIS WOULD LIKELY BE LIGHT AND COME TO AN
END LATE FRIDAY NIGHT/EARLY SAT MORNING.

HIGH TEMPERATURES AREA-WIDE LOOK TO REMAIN IN THE LOWER 40S AT BEST
ON FRIDAY AND SATURDAY

LONG TERM...SUNDAY THROUGH WEDNESDAY...

HIGH TEMPERATURES WILL MODERATE INTO EARLY NEXT WEEK AS THE
WESTERN CONUS UPPER RIDGE BUILDS EASTWARD OVER THE REGION. ANOTHER
COLD FRONT LOOKS TO TAKE AIM ON THE AREA AROUND NEXT
TUESDAY...WHICH WILL RESULT IN OUR NEXT CHANCE OF SHOWERS.
OTHERWISE TEMPERATURES LOOK TO REMAIN NEAR NORMAL DURING THE LATER
HALF OF THE WEEK.

KJB

&&

.AVIATION...

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

* RAIN SHOWERS OVERNIGHT.
* SNOW SHOWERS FRIDAY MORNING AND POSSIBLY LATE FRIDAY AFTERNOON.
* MVFR CIGS OVERNIGHT THRU FRIDAY MORNING.
* STRONG/GUSTY NORTHWEST WINDS OVERNIGHT.
* VERY STRONG/GUSTY NORTHERLY WINDS TO 40 KT FRIDAY. CMS

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

MULTIPLE FORECAST CONCERNS THIS PERIOD. LOW PRESSURE OVER THE
EASTERN U.P. WILL MOVE TO LAKE HURON BY MORNING. A TRAILING COLD
FRONT WILL MOVE ACROSS THE AREA LATE THIS EVENING INTO THE EARLY
MORNING HOURS...SHIFTING WESTERLY WINDS TO THE NORTHWEST WITH
SPEEDS SLOWLY INCREASING. AS COLDER AIR SPREADS ACROSS THE AREA
LATE THIS EVENING AND OVERNIGHT...RAIN SHOWERS ARE EXPECTED TO
DEVELOP...MOSTLY LIKELY RIGHT OVER THE TERMINALS. THERMAL PROFILES
SUGGEST PRECIP SHOULD REMAIN MAINLY RAIN THRU MUCH OF THE NIGHT
AND PERHAPS ONLY LAST A FEW HOURS THOUGH CONFIDENCE ON TIMING IS
LOW ENOUGH TO MAINTAIN VICINITY MENTION.

WINDS CONTINUE TO INCREASE FRIDAY MORNING AS COLDER AIR CONTINUES
TO POUR INTO THE REGION. AS WINDS SHIFT TO THE NORTH MID/LATE
MORNING...THERE WILL BE ANOTHER CHANCE FOR PRECIPITATION...BY THIS
TIME...THERMAL PROFILES ARE COLD ENOUGH FOR AT LEAST A MIX OF RAIN
AND SNOW BUT MAINTAINED SNOW SHOWERS FROM PREVIOUS FORECAST.
CONFIDENCE REGARDING SPECIFICS DURING THIS TIME PERIOD ARE LOW...
INCLUDING DURATION AND INTENSITY. AS THIS TIME PERIOD APPROACHES
AND TRENDS EMERGE ON RADAR...A SHORT DURATION TEMPO FOR LOWER
CONDITIONS MAY BE NEEDED.

CIGS SHOULD REMAIN VFR THIS EVENING AND LOWER TO MVFR OVERNIGHT
WITH THE POTENTIAL FOR A SHORT PERIOD OF LOW MVFR POSSIBLE. ONCE
PRECIP ENDS IN THE MORNING...CIGS SHOULD LIFT TO EITHER HIGH MVFR
OR LOW VFR.

WINDS WILL STEADILY INCREASE FROM THE EARLY MORNING THRU THE LATE
MORNING AND TURN NORTHERLY. PREVAILING SPEEDS IN THE MID 20 KT
RANGE LOOK ON TRACK WITH PREVAILING GUSTS INTO THE MID/UPPER 30KT
RANGE WITH THE POTENTIAL FOR GUSTS TO 40KTS IN THE LATE MORNING
AND EARLY AFTERNOON. SPEEDS/GUSTS WILL SLOWLY DIMINISH LATE IN THE
AFTERNOON...ESPECIALLY AT RFD...BUT WINDY CONDITIONS WILL CONTINUE
INTO FRIDAY EVENING.

AS FOR GYY AND LAKE EFFECT...A BAND OF LAKE EFFECT RAIN AND SNOW
IS EXPECTED TO DEVELOP BY MID MORNING AND CONTINUE INTO FRIDAY
EVENING...AFFECTING NORTHWEST INDIANA FOR MUCH OF THE DAY. THIS
PRECIPITATION IS EXPECTED TO BE QUIET INTENSE WITH THUNDER LIKELY.
IF THIS INTENSE PRECIP IS SUFFICIENT ENOUGH TO COOL THE LOWER
LAYERS...THE PRECIP MAY SWITCH OVER TO ALL OR PREDOMINANTLY SNOW.
CONFIDENCE IN HOW LONG THIS MAY PERSIST IS LOW AND MAINTAINED A
RAIN/SNOW MIX AT GYY WITH A PERIOD OF REDUCED VIS/CIGS IN THE
EARLY/MID AFTERNOON. SPECIFICS ARE DIFFICULT FROM THIS DISTANCE
AND CHANGES TO THE GYY FORECAST SHOULD BE EXPECTED.

SOME OF THE GUIDANCE SHOWS THIS LAKE EFFECT PRECIPITATION MOVING
BACK WEST TOWARD ORD/MDW LATE FRIDAY AFTERNOON INTO FRIDAY
EVENING. CONFIDENCE REGARDING THIS TREND IS ALSO LOW. HOWEVER...
THE BAND WILL BE CLOSE ENOUGH TO MDW TO ADD MENTION LATE IN THE
AFTERNOON WITH THIS FORECAST. IF PRECIP IS SNOW AND DOES MAKE IT
TO ORD/MDW...IFR CIGS/VIS ARE CERTAINLY POSSIBLE. CMS

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

* HIGH FOR RAIN SHOWERS OVERNIGHT.
* MEDIUM FOR SNOW SHOWERS FRIDAY MORNING...LOW FOR DURATION/
  INTENSITY.
* LOW FOR SNOW SHOWERS LATE FRIDAY AFTERNOON.
* MEDIUM FOR MVFR CIGS OVERNIGHT/FRIDAY MORNING.
* HIGH FOR WIND SPEEDS/GUSTS/DIRECTION THRU THE PERIOD...MEDIUM
  FOR TIMING/CHANGES. CMS

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

* SATURDAY...DRY/VFR. NORTHEAST WINDS 10-15 KT.
* SUNDAY...DRY/VFR. SOUTH WINDS 10-15 KT.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.
* TUESDAY...SHRA/MVFR LIKELY. SOUTHWEST WINDS.
* WEDNESDAY...DRY/VFR. SOUTHWEST WINDS.

&&

.MARINE...
250 PM CDT

A VERY ACTIVE PERIOD OVER LAKE MICHIGAN BEGINNING LATER TONIGHT. THE
AREA WILL FIND ITSELF IN A FAVORABLE AND ANOMALOUS SYNOPTIC WEATHER
PATTERN FOR STRONG NORTHERLY WINDS...AND THIS WILL BE FURTHER AIDED
BY THE WARM WATERS/EXTREME INSTABILITY TO PRODUCE REGULAR HIGHER END
STORM FORCE GUSTS PERSISTING INTO FRIDAY. A STRONG COLD FRONT WILL
MOVE DOWN THE LAKE RAPIDLY FROM AROUND MIDNIGHT THROUGH 5 AM.
IMMEDIATELY BEHIND THIS A VERY TIGHT PRESSURE GRADIENT IN SYNC WITH
COLD AIR ADVECTION WILL PRODUCE A RAMP UP IN NORTHERLY WIND SPEEDS.
THE HIGHEST WIND SPEEDS OF STORM FORCE TO 50 AND POSSIBLY EVEN 55 KT
ARE EXPECTED LATE TONIGHT THROUGH MID FRIDAY AFTERNOON FOR THE
CENTRAL AND SOUTHERN PART OF THE LAKE...AND AFTER DAYBREAK THROUGH
THE DAY ON FRIDAY FOR THE NEARSHORE AREAS OF ILLINOIS AND INDIANA.
THE WAVE MAXIMUM OF OVER 20 FOOTERS IS EXPECTED TO DEVELOP OVER THE
CENTRAL PART OF THE LAKE EARLY FRIDAY MORNING AND EVOLVE SOUTHWARD
REACHING THE ILLINOIS AND INDIANA NEARSHORE FRIDAY AFTERNOON AND
EARLY EVENING. WAVES WILL BE VERY SLOW TO SUBSIDE THROUGH LATE
FRIDAY NIGHT AND EARLY SATURDAY. HIGH PRESSURE WILL MOVE QUICKLY
OVER THE LAKE SATURDAY NIGHT BEFORE SOUTHERLY FLOW RETURNS TO THE
LAKE.

MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WIND ADVISORY...ILZ014...7 AM FRIDAY TO 10 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022...7
AM
     FRIDAY TO 7 PM FRIDAY.

     WIND ADVISORY...ILZ023-ILZ033...10 AM FRIDAY TO 7 PM FRIDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011...10 AM
     FRIDAY TO 10 PM FRIDAY.

     WIND ADVISORY...INZ019...10 AM FRIDAY TO 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 PM FRIDAY TO
     4 AM SATURDAY.

     STORM WARNING...
LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
     LMZ878...3 AM FRIDAY TO 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563...1 AM FRIDAY TO 10
     PM FRIDAY.

     GALE WARNING...LMZ740...4 AM FRIDAY TO 4 AM SATURDAY.

     STORM WARNING...LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...4 AM
FRIDAY
     TO 7 PM FRIDAY.

&&

$$

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

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000
FXUS63 KILX 310137
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
837 PM CDT Thu Oct 30 2014

.UPDATE...
ISSUED AT 830 PM CDT THU OCT 30 2014

Initial shortwave pushing across west central Illinois has brought
about some scattered showers this evening over most of our area.
A second and more potent upper wave seen on the water vapor loop
streaming south over the upper Great Lakes and that feature will
deepen in over the lower lakes tomorrow morning ushering much
colder air and strong northerly winds to the region. First band
of rain will shift into eastern and southeast Illinois this
evening with a second band of rain forecast to shift southeast
into our area along the quick moving cold front after midnight. 3
hourly pressure rises of 4 to 6 mb streaking southeast along the
cold front to our northwest and as the upper feature deepens in
over the lower lakes region, we should see some rather significant
pres rises develop just to our north and west which should bring
in the strong winds around sunrise across the north and during the
morning to the south.

Will continue to hold on to the POPs over most of the area until
that second wave tracks thru the area by Friday morning, with rain
chances then confined to far east and southeast Illinois. RAP and
HRRR indicating the potential for gusts of 40 to 45 mph tomorrow
morning into the afternoon hours across most of the area coupled
with steady or slowly falling temperatures. Wind chill readings
for the trick or treaters will be in the upper 20s to lower 30s
tomorrow evening!

Have already sent out an updated ZFP to address the more widespread
nature of the precip earlier in the evening and will have another
update out by 900 pm to adjust the late evening wording.

&&

.SHORT TERM...(Tonight)
ISSUED AT 300 PM CDT THU OCT 30 2014

Two waves impacting the short term.  The first low is over western
Missouri and weak lift associated with weak frontogenesis sparking
some showers for the region.  Plenty of dry air in the area is also
helping to erode the showers and keep them more scattered in
nature.  Cooler air on the way, with another shot of cold air
deepening the trof aloft with the next wave later this evening.
This second wave acting a bit more like a cold front with the wind
shift to more north/northwesterly winds tonight and cold air, but
the models are having a hard time with precip.  Current precip is
overblown in the models, and the later wave (after midnight) is even
more sketchy with QPF.  As a result, pops are minimal in association
with the second wave...and instead follow the progression of the
current precip out to the east by midnight. Temps currently on the
cooler side of guidance as the temps have not dropped far enough in
the last 24 hours and that trend may continue, though the RH will be
plenty for clouds, if not for ongoing precip. Tightening pressure
gradient behind the boundary resulting in winds ramping up in the
early morning hours in advance of a blustery cold day.

&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 300 PM CDT THU OCT 30 2014

A vigorous cold Canadian shortwave will drop southward into the
Midwest by Friday morning. A strong cold front with this feature
will usher in much colder air to central Illinois for Friday, with
highs only reaching the 40s. North-northwest winds 20-30 mph with
gusts 35-40 mph will develop along and behind the cold front,
bringing wind chills into the 30s for the afternoon. Little
precipitation will remain behind the front, however slight chances
will remain near the IL/IN border. Forecast soundings in this area
indicate wet bulb temperatures below freezing to ground level below
the precipitation generation level, and this should allow for light
snow or mixed rain and snow reaching the ground Friday afternoon and
evening. Breezy and cold conditions will continue into the evening
for Halloween Trick or Treat conditions with temperatures dropping
quickly into the 30s and wind chill values into the 20s.

Friday night, light north winds will continue, while the cold air
mass results in temperatures reaching 25-30 degrees for the first
widespread freeze of the season. Have issued a freeze warning to
account for this.

Little warming is expected through Sunday morning, with another
freezing night expected. A mild and moist southwesterly low level
flow will develop late in the weekend through early next week as an
upper level ridge shifts eastward across Illinois and a deep trough
crosses the Rockies. This trough will bring good chances of showers
late Monday through tuesday night as the system moves into the Ohio
river valley. Isolated thunderstorms may also occur Monday night and
Tue south of I-72. Drier weather is expected Wed night and Thu as
dry northwesterly flow trails the system.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 605 PM CDT THU OCT 30 2014

Low VFR cigs expected thru the evening hours and then will have to
watch for the possibility for at least a brief period of MVFR cigs
with a cold frontal passage after 07z tonight with the main concern
after that being strong northerly winds on Friday. First batch of
rain tracking south-southeast across the area early this evening
and will continue with tempo groups over mainly the eastern TAF
sites for a few hours early this evening. We will probably see a
brief break in any precip chances later this evening before a much
stronger wave shifts south into the lower Great Lakes bringing
another threat for scattered showers and a wind shift into the
north at all TAF sites in the 07z-10z time frame. This is the time
frame where we may see a brief period of MVFR cigs but for now,
will only include a scattered group around 2500 feet. Once the
front shifts south of our area, surface winds will increase to
between 20 and 30 kts by mid morning with gusts to around 35 kts
at times.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING from Midnight Friday Night to 9 AM CDT Saturday
FOR ILZ027>031-036>038-040>057-061>063-066>068-071>073.

&&

$$

UPDATE...Smith
SHORT TERM...HJS
LONG TERM...Onton
AVIATION...Smith






000
FXUS63 KLOT 310017
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
717 PM CDT THU OCT 30 2014

.DISCUSSION...

EARLY EVENING UPDATE...

MADE A FEW ADJUSTMENTS TO FORECAST TO INCREASE POPS ACROSS SOUTHERN
CWA WHERE WEST-EAST BAND OF MODERATE RAIN HAD DEVELOPED LATE IN THE
AFTERNOON...AND TO SLOW ARRIVAL OF POPS ACROSS THE NORTHERN COUNTIES
A BIT IN LINE WITH VARIOUS HIGH-RES NEAR TERM MODELS WITH APPROACH
OF COLD FRONT LATER THIS EVENING.

RAIN BAND ACROSS LIVINGSTON...FORD IROQUOIS AND BENTON COUNTIES
APPEARS TO BE ASSOCIATED WITH MID-LEVEL FRONTOGENETICAL FORCING WITH
INITIAL SHORT WAVE PROPAGATING SOUTHEAST ACROSS MO/IL INTO THE LOWER
OH AND TENNESSEE VALLEYS. THIS SHOULD SCOOT OFF TO THE SOUTHEAST
OVER THE NEXT COUPLE OF HOURS. FARTHER NORTHWEST...COLD FRONT WAS
DEVELOPING SOUTHEASTWARD ACROSS SOUTHEAST MINNESOTA AND
NORTHWEST/WESTERN WISCONSIN IN RESPONSE TO STRENGTHENING PRESSURE
RISES WITH STRONG HIGH BUILDING SOUTHEAST FROM CANADA. LITTLE IN
RADAR DETECTABLE PRECIP OCCURRING ACROSS THOSE AREAS AT THIS TIME
THUS HAVE SLOWED ARRIVAL AND SLIGHTLY LOWERED POPS FOR SHOWERS
ACROSS NORTHERN IL DURING THE EARLY EVENING HOURS...MORE ALONG THE
CONCENSUS OF THE RAP/HRRR/LOCAL ARW AND EVEN MANY OF THE SYNOPTIC
SCALE MODELS WHICH HOLD MEASURABLE PRECIP OFF LARGELY UNTIL MIDNIGHT
OR AFTER.

RATZER

PREVIOUS DISCUSSION FROM 332 PM CDT...

SHORT TERM...TONIGHT THROUGH SATURDAY...
THE MAIN FORECAST FOCUS THIS AFTERNOON CONTINUES TO CENTER AROUND
THE STORM SYSTEM EXPECTED IMPACT THE REGION LATE TONIGHT THROUGH
FRIDAY NIGHT. STRONG WINDS...AND THE POTENTIAL FOR SOME PERIODS OF
HEAVY LAKE EFFECT SNOW ARE THE PRIMARY CONCERNS.

WE ARE ISSUING A WIND ADVISORY FOR MOST OF THE EASTERN HALF OF THE
AREA...WITH THE EXCEPTION OF LAKE...PORTER...JASPER AND NEWTON
COUNTIES IN INDIANA...WHERE A WINTER WEATHER ADVISORY IS BEING
ISSUED. SEE BELOW FOR MORE DETAILS.

WATER VAPOR IMAGERY EARLY THIS AFTERNOON SHOWS A RATHER VIGOROUS
UPPER LEVEL IMPULSE NOW MOVING JUST EAST OF LAKE WINNIPEG AND OVER
FAR SOUTHWESTERN ONTARIO. THIS WAVE IS EXPECTED TO CONTINUE DIGGING
SOUTH-SOUTHEASTWARD TONIGHT ALONG THE EASTERN PERIPHERY OF AN UPPER
RIDGE...CURRENT CENTERED ACROSS THE INTER MOUNTAIN WEST. AS THIS
OCCURS...AN AREA OF SURFACE LOW PRESSURE WILL SHIFT SOUTHWARD ACROSS
LOWER MICHIGAN INTO FRIDAY MORNING. FARTHER NORTHWEST...A RATHER
STOUT 1036 MB HIGH IS ALSO EXPECTED TO RAPIDLY BUILD SOUTHEASTWARD
ACROSS THE DAKOTAS AND UPPER MIDWEST INTO FRIDAY. THIS STILL LOOKS
TO SET THE STAGE FOR STRONG NORTHERN WINDS ACROSS THE AREA DURING
THE DAY FRIDAY AS STRONG PRESSURE RISES AND STRONG COLD AIR
ADVECTION LEAD TO A QUICK RAMP UP OF NORTHERLY WINDS IN THE WAKE OF
A COLD FRONTAL PASSAGE LATE TONIGHT. MODEL SOUNDINGS ALL SUGGEST
MEAN MIXING LAYER WIND SPEEDS COULD TOP 40 KT ACROSS MAINLY THE
EASTERN HALF OF THE AREA INLAND FROM THE LAKE...MEANING WIND GUSTS
COULD EASILY REACH THIS MAGNITUDE IN MOST AREAS. HOWEVER...AREAS
DIRECTLY ADJACENT TO LAKE MICHIGAN IN NORTHEASTERN ILLINOIS AND
NORTHWESTERN INDIANA COULD EXPERIENCE EVEN STRONGER GUSTS UP AROUND
50 KT WITH THE STRONG NORTHERLY ONSHORE COMPONENT TO THE WINDS.
WINDS LOOK TO REMAIN INTO THE EVENING ON HALLOWEEN...THOUGH WIND
SPEEDS SHOULD GRADUALLY WEAKEN THROUGH THE NIGHT.

THE LAKE SHORE FLOOD ADVISORY WILL CONTINUE FOR AREAS NEAR THE LAKE
AS LARGE BATTERING WAVES IN EXCESS OF 20 FT APPEAR LIKELY...AND AS
THE PREVIOUS DISCUSSION MENTIONED...LAKE LEVELS ARE ABOUT 2 FT
HIGHER THAN PAST YEARS...WHICH COULD MAKE THE IMPACTS OF THESE WAVES
HIGHER THEN SIMILAR WAVE EVENTS IN THE PAST COUPLE OF YEARS.

DUE TO THE LIKELIHOOD OF THESE STRONG WINDS...WE HAVE ISSUED A WIND
ADVISORY FOR MUCH OF THE EASTERN HALF OF MY CWA. THIS
INCLUDES AREAS BASICALLY ALONG AND EAST OF A LINE FROM HARVARD
SOUTHWARD THROUGH KANKAKEE AND IROQUOIS COUNTIES. THE ONLY EXCEPTION
TO THIS WIND ADVISORY IS FOR LAKE COUNTY INDIANA...AS WELL AS
PORTER...JASPER AND NEWTON COUNTIES...WHERE A WINTER WEATHER
ADVISORY IS BEING ISSUED IN PLACE OF A WIND ADVISORY FOR THE
COMBINATION OF THESE STRONG WINDS AND ALSO THE INCREASING POTENTIAL
FOR SOME ACCUMULATING LAKE EFFECT SNOW ON FRIDAY INTO FRIDAY
EVENING.

PRECIPITATION WITH THE APPROACHING COLD FRONT AND UPPER LEVEL
IMPULSE
WILL LIKELY BEGIN TO ENTER FAR NORTHERN ILLINOIS AFTER 10 PM THIS
EVENING...AND BE IN THE FORM OF RAIN SHOWERS. THIS INITIAL ROUND OF
SHOWERS SHOULD MOVE SOUTHWARD ACROSS THE AREA THROUGH THE NIGHT...IN
CLOSE PROXIMITY THE INCREASING FRONTOGENESIS IN THE VICINITY OF THE
COLD FRONTAL BOUNDARY. THIS SHOULD BE A FAIRLY PROGRESSIVE AREA OF
SHOWERS...WITH MOST AREAS ACROSS NORTH CENTRAL ILLINOIS DRYING OUT
BY EARLY FRIDAY MORNING.

THE SECOND STAGE OF PRECIPITATION WILL BE MORE OF A TRUE LAKE EFFECT
SETUP. A COLD AIRMASS FEATURING -7 DEGREE C TEMPERATURES AT 850 MB
WILL MOVE OVER THE LAKE...WHICH IS CURRENTLY REPORTING A 53F (11.7C)
DEGREE WATER TEMPERATURE AT THE SOUTH BUOY. THEREFORE...DELTA T`S
SHOULD END UP VERY FAVORABLE AROUND 19 DEGREES C. IN ADDITION...DEEP
LAKE INDUCED INSTABILITY IS STILL EXPECTED...WITH EQUILIBRIUM LEVELS
LIKELY TO REACH OR EVEN EXCEED 16,000 FT AGL. THEREFORE...THE THREAT
FOR THUNDER AND LIGHTNING HAS NOT CHANGED...WITH CONVECTIVE
PROCESSES
LIKELY TO BE MORE THAN DEEP ENOUGH THROUGH THE -10 TO -20 LAYER TO
RESULT IN GOOD CHARGE SEPARATION.

IT LOOKS AS THOUGH THIS LAKE EFFECT BAND COULD BEGIN TO SET UP
ACROSS NORTHWESTERN INDIANA AND PERHAPS PORTIONS OF SOUTHEASTERN
COOK COUNTY BY LATE FRIDAY MORNING. HI RES GUIDANCE SUGGESTS
UNCERTAINTY ON THE EXACT AREAS THAT WILL GET THIS LAKE EFFECT
BANDING. SOME HAVE HINTED IN A FARTHER WEST BAND...WHICH WOULD
IMPACT MORE OF THE CHICAGO AREA. HOWEVER...I THINK AT THIS POINT
AREAS IN NORTHWEST INDIANA WILL BE MORE FAVORED...WITH THE
LIKELIHOOD OF A NEARLY DUE NORTH BOUNDARY LAYER FLOW SETTING UP OVER
LAKE MICHIGAN. THIS WOULD TEND TO FAVOR BETTER BOUNDARY LAYER
CONVERGENCE ALONG THE SOUTHERN TIP OF LAKE MICHIGAN FRIDAY
AFTERNOON...WHICH SUGGESTS THAT PORTER AND LAKE INDIANA WILL BE MORE
IN LINE WITH THE POTENTIAL HEAVIER PRECIPITATION. DUE TO THE STRONG
WINDS...IT IS ALSO LIKELY THAT THIS LAKE EFFECT PRECIP COULD BE
DRIVEN WELL INLAND ACROSS NORTHWESTERN INDIANA...POSSIBLY IMPACTING
MUCH OF JASPER AND PORTER COUNTIES AS WELL.

UNCERTAINTY IN PRECIPITATION TYPE IS STILL SOMEWHAT HIGH...AS
SOME WARMER AIR MOVING OFF THE LAKE SHOULD MAKE BOUNDARY LAYER
TEMPERATURES MARGINAL FOR SNOW TO REACH THE SURFACE. HOWEVER...WITH
THE AFOREMENTIONED CONVECTIVE INSTABILITY AND THE GOOD POTENTIAL FOR
SOME HEAVIER PRECIP RATES...IT IS VERY MUCH IN THE REALM OF
POSSIBILITIES THAT ENHANCED DYNAMIC COOLING COULD RESULT IN A COLD
ENOUGH BOUNDARY LAYER SUPPORTIVE OF HEAVY SNOW. IT APPEARS THAT
AREAS INLAND FROM THE IMMEDIATE LAKE SHORE WOULD HAVE THE BEST
POTENTIAL FOR SNOW...THOUGH EVEN AREAS ALONG THE LAKE COULD CHANGE
OVER/MIX WITH SNOW. OVERALL...WITH THE POTENTIAL FOR SOME HEAVIER
BANDS OF SNOW WITH SOME ACCUMULATIONS POSSIBLE (POSSIBLY A FEW
INCHES IN SOME AREAS) ALONG WITH THE VERY STRONG NORTHERLY
WINDS...WE HAVE CHOSEN TO ISSUE THE WINTER WEATHER ADVISORY FOR THE
4 NORTHWESTERN INDIANA COUNTIES. IF...HOWEVER...THE TRANSITION TO
SNOW DOES NOT PAN OUT AS CURRENT THINKING SUGGESTS...WINDS WOULD BE
THE MAIN HAZARD ON FRIDAY...AND THE WINTER WEATHER ADVISORY COULD
THEN BE REPLACED WITH A WIND ADVISORY. THEREFORE...IN SPITE OF THE
UNCERTAINTIES ON WHEN CHANGE OVERS TO SNOW WILL OCCUR AND HOW MUCH
SNOW WILL ACTUALLY FALL...WE FEEL AT THIS POINT...TO ERROR ON THE
SIDE OF CAUTION...AS THERE IS A POTENTIAL FOR SOME VERY HEAVY SNOW
IN ADDITION TO THE STRONG WINDS.

THE WINDS ARE EXPECTED TO GRADUALLY VEER MORE NORTHEASTERLY FRIDAY
NIGHT...AND THIS COULD ALLOW SOME OF THE LAKE EFFECT PRECIPITATION
TO GET INTO NORTHEASTERN ILLINOIS FOR A BRIEF PERIOD FRIDAY EVENING.
HOWEVER...MODEL GUIDANCE CONTINUES TO SUGGEST THAT INVERSION HEIGHTS
WILL CRASH IN A HURRY BY LATE FRIDAY EVENING AS HEIGHTS AND
TEMPERATURES BEGIN TO RISE ALOFT. THEREFORE...ANY SNOW SHOWERS THAT
GET INTO NORTHEASTERN ILLINOIS WOULD LIKELY BE LIGHT AND COME TO AN
END LATE FRIDAY NIGHT/EARLY SAT MORNING.

HIGH TEMPERATURES AREA-WIDE LOOK TO REMAIN IN THE LOWER 40S AT BEST
ON FRIDAY AND SATURDAY

LONG TERM...SUNDAY THROUGH WEDNESDAY...

HIGH TEMPERATURES WILL MODERATE INTO EARLY NEXT WEEK AS THE
WESTERN CONUS UPPER RIDGE BUILDS EASTWARD OVER THE REGION. ANOTHER
COLD FRONT LOOKS TO TAKE AIM ON THE AREA AROUND NEXT
TUESDAY...WHICH WILL RESULT IN OUR NEXT CHANCE OF SHOWERS.
OTHERWISE TEMPERATURES LOOK TO REMAIN NEAR NORMAL DURING THE LATER
HALF OF THE WEEK.

KJB

&&

.AVIATION...

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

* RAIN SHOWERS OVERNIGHT.
* SNOW SHOWERS FRIDAY MORNING AND POSSIBLY LATE FRIDAY AFTERNOON.
* MVFR CIGS OVERNIGHT THRU FRIDAY MORNING.
* STRONG/GUSTY NORTHWEST WINDS OVERNIGHT.
* VERY STRONG/GUSTY NORTHERLY WINDS TO 40 KT FRIDAY. CMS

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

MULTIPLE FORECAST CONCERNS THIS PERIOD. LOW PRESSURE OVER THE
EASTERN U.P. WILL MOVE TO LAKE HURON BY MORNING. A TRAILING COLD
FRONT WILL MOVE ACROSS THE AREA LATE THIS EVENING INTO THE EARLY
MORNING HOURS...SHIFTING WESTERLY WINDS TO THE NORTHWEST WITH
SPEEDS SLOWLY INCREASING. AS COLDER AIR SPREADS ACROSS THE AREA
LATE THIS EVENING AND OVERNIGHT...RAIN SHOWERS ARE EXPECTED TO
DEVELOP...MOSTLY LIKELY RIGHT OVER THE TERMINALS. THERMAL PROFILES
SUGGEST PRECIP SHOULD REMAIN MAINLY RAIN THRU MUCH OF THE NIGHT
AND PERHAPS ONLY LAST A FEW HOURS THOUGH CONFIDENCE ON TIMING IS
LOW ENOUGH TO MAINTAIN VICINITY MENTION.

WINDS CONTINUE TO INCREASE FRIDAY MORNING AS COLDER AIR CONTINUES
TO POUR INTO THE REGION. AS WINDS SHIFT TO THE NORTH MID/LATE
MORNING...THERE WILL BE ANOTHER CHANCE FOR PRECIPITATION...BY THIS
TIME...THERMAL PROFILES ARE COLD ENOUGH FOR AT LEAST A MIX OF RAIN
AND SNOW BUT MAINTAINED SNOW SHOWERS FROM PREVIOUS FORECAST.
CONFIDENCE REGARDING SPECIFICS DURING THIS TIME PERIOD ARE LOW...
INCLUDING DURATION AND INTENSITY. AS THIS TIME PERIOD APPROACHES
AND TRENDS EMERGE ON RADAR...A SHORT DURATION TEMPO FOR LOWER
CONDITIONS MAY BE NEEDED.

CIGS SHOULD REMAIN VFR THIS EVENING AND LOWER TO MVFR OVERNIGHT
WITH THE POTENTIAL FOR A SHORT PERIOD OF LOW MVFR POSSIBLE. ONCE
PRECIP ENDS IN THE MORNING...CIGS SHOULD LIFT TO EITHER HIGH MVFR
OR LOW VFR.

WINDS WILL STEADILY INCREASE FROM THE EARLY MORNING THRU THE LATE
MORNING AND TURN NORTHERLY. PREVAILING SPEEDS IN THE MID 20 KT
RANGE LOOK ON TRACK WITH PREVAILING GUSTS INTO THE MID/UPPER 30KT
RANGE WITH THE POTENTIAL FOR GUSTS TO 40KTS IN THE LATE MORNING
AND EARLY AFTERNOON. SPEEDS/GUSTS WILL SLOWLY DIMINISH LATE IN THE
AFTERNOON...ESPECIALLY AT RFD...BUT WINDY CONDITIONS WILL CONTINUE
INTO FRIDAY EVENING.

AS FOR GYY AND LAKE EFFECT...A BAND OF LAKE EFFECT RAIN AND SNOW
IS EXPECTED TO DEVELOP BY MID MORNING AND CONTINUE INTO FRIDAY
EVENING...AFFECTING NORTHWEST INDIANA FOR MUCH OF THE DAY. THIS
PRECIPITATION IS EXPECTED TO BE QUIET INTENSE WITH THUNDER LIKELY.
IF THIS INTENSE PRECIP IS SUFFICIENT ENOUGH TO COOL THE LOWER
LAYERS...THE PRECIP MAY SWITCH OVER TO ALL OR PREDOMINANTLY SNOW.
CONFIDENCE IN HOW LONG THIS MAY PERSIST IS LOW AND MAINTAINED A
RAIN/SNOW MIX AT GYY WITH A PERIOD OF REDUCED VIS/CIGS IN THE
EARLY/MID AFTERNOON. SPECIFICS ARE DIFFICULT FROM THIS DISTANCE
AND CHANGES TO THE GYY FORECAST SHOULD BE EXPECTED.

SOME OF THE GUIDANCE SHOWS THIS LAKE EFFECT PRECIPITATION MOVING
BACK WEST TOWARD ORD/MDW LATE FRIDAY AFTERNOON INTO FRIDAY
EVENING. CONFIDENCE REGARDING THIS TREND IS ALSO LOW. HOWEVER...
THE BAND WILL BE CLOSE ENOUGH TO MDW TO ADD MENTION LATE IN THE
AFTERNOON WITH THIS FORECAST. IF PRECIP IS SNOW AND DOES MAKE IT
TO ORD/MDW...IFR CIGS/VIS ARE CERTAINLY POSSIBLE. CMS

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

* HIGH FOR RAIN SHOWERS OVERNIGHT.
* MEDIUM FOR SNOW SHOWERS FRIDAY MORNING...LOW FOR DURATION/
  INTENSITY.
* LOW FOR SNOW SHOWERS LATE FRIDAY AFTERNOON.
* MEDIUM FOR MVFR CIGS OVERNIGHT/FRIDAY MORNING.
* HIGH FOR WIND SPEEDS/GUSTS/DIRECTION THRU THE PERIOD...MEDIUM
  FOR TIMING/CHANGES. CMS

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

* SATURDAY...DRY/VFR. NORTHEAST WINDS 10-15 KT.
* SUNDAY...DRY/VFR. SOUTH WINDS 10-15 KT.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.
* TUESDAY...SHRA/MVFR LIKELY. SOUTHWEST WINDS.
* WEDNESDAY...DRY/VFR. SOUTHWEST WINDS.

&&

.MARINE...
250 PM CDT

A VERY ACTIVE PERIOD OVER LAKE MICHIGAN BEGINNING LATER TONIGHT. THE
AREA WILL FIND ITSELF IN A FAVORABLE AND ANOMALOUS SYNOPTIC WEATHER
PATTERN FOR STRONG NORTHERLY WINDS...AND THIS WILL BE FURTHER AIDED
BY THE WARM WATERS/EXTREME INSTABILITY TO PRODUCE REGULAR HIGHER END
STORM FORCE GUSTS PERSISTING INTO FRIDAY. A STRONG COLD FRONT WILL
MOVE DOWN THE LAKE RAPIDLY FROM AROUND MIDNIGHT THROUGH 5 AM.
IMMEDIATELY BEHIND THIS A VERY TIGHT PRESSURE GRADIENT IN SYNC WITH
COLD AIR ADVECTION WILL PRODUCE A RAMP UP IN NORTHERLY WIND SPEEDS.
THE HIGHEST WIND SPEEDS OF STORM FORCE TO 50 AND POSSIBLY EVEN 55 KT
ARE EXPECTED LATE TONIGHT THROUGH MID FRIDAY AFTERNOON FOR THE
CENTRAL AND SOUTHERN PART OF THE LAKE...AND AFTER DAYBREAK THROUGH
THE DAY ON FRIDAY FOR THE NEARSHORE AREAS OF ILLINOIS AND INDIANA.
THE WAVE MAXIMUM OF OVER 20 FOOTERS IS EXPECTED TO DEVELOP OVER THE
CENTRAL PART OF THE LAKE EARLY FRIDAY MORNING AND EVOLVE SOUTHWARD
REACHING THE ILLINOIS AND INDIANA NEARSHORE FRIDAY AFTERNOON AND
EARLY EVENING. WAVES WILL BE VERY SLOW TO SUBSIDE THROUGH LATE
FRIDAY NIGHT AND EARLY SATURDAY. HIGH PRESSURE WILL MOVE QUICKLY
OVER THE LAKE SATURDAY NIGHT BEFORE SOUTHERLY FLOW RETURNS TO THE
LAKE.

MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WIND ADVISORY...ILZ014...7 AM FRIDAY TO 10 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022...7 AM
     FRIDAY TO 7 PM FRIDAY.

     WIND ADVISORY...ILZ023-ILZ033...10 AM FRIDAY TO 7 PM FRIDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011...10 AM
     FRIDAY TO 10 PM FRIDAY.

     WIND ADVISORY...INZ019...10 AM FRIDAY TO 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 PM FRIDAY TO
     4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
     LMZ878...3 AM FRIDAY TO 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563...1 AM FRIDAY TO 10
     PM FRIDAY.

     GALE WARNING...LMZ740...4 AM FRIDAY TO 4 AM SATURDAY.

     STORM WARNING...LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...4 AM FRIDAY
     TO 7 PM FRIDAY.

&&

$$

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000
FXUS63 KLOT 302322 CCA
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
620 PM CDT THU OCT 30 2014

.DISCUSSION...

EARLY EVENING UPDATE...

MADE A FEW ADJUSTMENTS TO FORECAST TO INCREASE POPS ACROSS SOUTHERN
CWA WHERE WEST-EAST BAND OF MODERATE RAIN HAD DEVELOPED LATE IN THE
AFTERNOON...AND TO SLOW ARRIVAL OF POPS ACROSS THE NORTHERN COUNTIES
A BIT IN LINE WITH VARIOUS HIGH-RES NEAR TERM MODELS WITH APPROACH
OF COLD FRONT LATER THIS EVENING.

RAIN BAND ACROSS LIVINGSTON...FORD IROQUOIS AND BENTON COUNTIES
APPEARS TO BE ASSOCIATED WITH MID-LEVEL FRONTOGENETICAL FORCING WITH
INITIAL SHORT WAVE PROPAGATING SOUTHEAST ACROSS MO/IL INTO THE LOWER
OH AND TENNESSEE VALLEYS. THIS SHOULD SCOOT OFF TO THE SOUTHEAST
OVER THE NEXT COUPLE OF HOURS. FARTHER NORTHWEST...COLD FRONT WAS
DEVELOPING SOUTHEASTWARD ACROSS SOUTHEAST MINNESOTA AND
NORTHWEST/WESTERN WISCONSIN IN RESPONSE TO STRENGTHENING PRESSURE
RISES WITH STRONG HIGH BUILDING SOUTHEAST FROM CANADA. LITTLE IN
RADAR DETECTABLE PRECIP OCCURRING ACROSS THOSE AREAS AT THIS TIME
THUS HAVE SLOWED ARRIVAL AND SLIGHTLY LOWERED POPS FOR SHOWERS
ACROSS NORTHERN IL DURING THE EARLY EVENING HOURS...MORE ALONG THE
CONCENSUS OF THE RAP/HRRR/LOCAL ARW AND EVEN MANY OF THE SYNOPTIC
SCALE MODELS WHICH HOLD MEASURABLE PRECIP OFF LARGELY UNTIL MIDNIGHT
OR AFTER.

RATZER

PREVIOUS DISCUSSION FROM 332 PM CDT...

SHORT TERM...TONIGHT THROUGH SATURDAY...
THE MAIN FORECAST FOCUS THIS AFTERNOON CONTINUES TO CENTER AROUND
THE STORM SYSTEM EXPECTED IMPACT THE REGION LATE TONIGHT THROUGH
FRIDAY NIGHT. STRONG WINDS...AND THE POTENTIAL FOR SOME PERIODS OF
HEAVY LAKE EFFECT SNOW ARE THE PRIMARY CONCERNS.

WE ARE ISSUING A WIND ADVISORY FOR MOST OF THE EASTERN HALF OF THE
AREA...WITH THE EXCEPTION OF LAKE...PORTER...JASPER AND NEWTON
COUNTIES IN INDIANA...WHERE A WINTER WEATHER ADVISORY IS BEING
ISSUED. SEE BELOW FOR MORE DETAILS.

WATER VAPOR IMAGERY EARLY THIS AFTERNOON SHOWS A RATHER VIGOROUS
UPPER LEVEL IMPULSE NOW MOVING JUST EAST OF LAKE WINNIPEG AND OVER
FAR SOUTHWESTERN ONTARIO. THIS WAVE IS EXPECTED TO CONTINUE DIGGING
SOUTH-SOUTHEASTWARD TONIGHT ALONG THE EASTERN PERIPHERY OF AN UPPER
RIDGE...CURRENT CENTERED ACROSS THE INTER MOUNTAIN WEST. AS THIS
OCCURS...AN AREA OF SURFACE LOW PRESSURE WILL SHIFT SOUTHWARD ACROSS
LOWER MICHIGAN INTO FRIDAY MORNING. FARTHER NORTHWEST...A RATHER
STOUT 1036 MB HIGH IS ALSO EXPECTED TO RAPIDLY BUILD SOUTHEASTWARD
ACROSS THE DAKOTAS AND UPPER MIDWEST INTO FRIDAY. THIS STILL LOOKS
TO SET THE STAGE FOR STRONG NORTHERN WINDS ACROSS THE AREA DURING
THE DAY FRIDAY AS STRONG PRESSURE RISES AND STRONG COLD AIR
ADVECTION LEAD TO A QUICK RAMP UP OF NORTHERLY WINDS IN THE WAKE OF
A COLD FRONTAL PASSAGE LATE TONIGHT. MODEL SOUNDINGS ALL SUGGEST
MEAN MIXING LAYER WIND SPEEDS COULD TOP 40 KT ACROSS MAINLY THE
EASTERN HALF OF THE AREA INLAND FROM THE LAKE...MEANING WIND GUSTS
COULD EASILY REACH THIS MAGNITUDE IN MOST AREAS. HOWEVER...AREAS
DIRECTLY ADJACENT TO LAKE MICHIGAN IN NORTHEASTERN ILLINOIS AND
NORTHWESTERN INDIANA COULD EXPERIENCE EVEN STRONGER GUSTS UP AROUND
50 KT WITH THE STRONG NORTHERLY ONSHORE COMPONENT TO THE WINDS.
WINDS LOOK TO REMAIN INTO THE EVENING ON HALLOWEEN...THOUGH WIND
SPEEDS SHOULD GRADUALLY WEAKEN THROUGH THE NIGHT.

THE LAKE SHORE FLOOD ADVISORY WILL CONTINUE FOR AREAS NEAR THE LAKE
AS LARGE BATTERING WAVES IN EXCESS OF 20 FT APPEAR LIKELY...AND AS
THE PREVIOUS DISCUSSION MENTIONED...LAKE LEVELS ARE ABOUT 2 FT
HIGHER THAN PAST YEARS...WHICH COULD MAKE THE IMPACTS OF THESE WAVES
HIGHER THEN SIMILAR WAVE EVENTS IN THE PAST COUPLE OF YEARS.

DUE TO THE LIKELIHOOD OF THESE STRONG WINDS...WE HAVE ISSUED A WIND
ADVISORY FOR MUCH OF THE EASTERN HALF OF MY CWA. THIS
INCLUDES AREAS BASICALLY ALONG AND EAST OF A LINE FROM HARVARD
SOUTHWARD THROUGH KANKAKEE AND IROQUOIS COUNTIES. THE ONLY EXCEPTION
TO THIS WIND ADVISORY IS FOR LAKE COUNTY INDIANA...AS WELL AS
PORTER...JASPER AND NEWTON COUNTIES...WHERE A WINTER WEATHER
ADVISORY IS BEING ISSUED IN PLACE OF A WIND ADVISORY FOR THE
COMBINATION OF THESE STRONG WINDS AND ALSO THE INCREASING POTENTIAL
FOR SOME ACCUMULATING LAKE EFFECT SNOW ON FRIDAY INTO FRIDAY
EVENING.

PRECIPITATION WITH THE APPROACHING COLD FRONT AND UPPER LEVEL
IMPULSE
WILL LIKELY BEGIN TO ENTER FAR NORTHERN ILLINOIS AFTER 10 PM THIS
EVENING...AND BE IN THE FORM OF RAIN SHOWERS. THIS INITIAL ROUND OF
SHOWERS SHOULD MOVE SOUTHWARD ACROSS THE AREA THROUGH THE NIGHT...IN
CLOSE PROXIMITY THE INCREASING FRONTOGENESIS IN THE VICINITY OF THE
COLD FRONTAL BOUNDARY. THIS SHOULD BE A FAIRLY PROGRESSIVE AREA OF
SHOWERS...WITH MOST AREAS ACROSS NORTH CENTRAL ILLINOIS DRYING OUT
BY EARLY FRIDAY MORNING.

THE SECOND STAGE OF PRECIPITATION WILL BE MORE OF A TRUE LAKE EFFECT
SETUP. A COLD AIRMASS FEATURING -7 DEGREE C TEMPERATURES AT 850 MB
WILL MOVE OVER THE LAKE...WHICH IS CURRENTLY REPORTING A 53F (11.7C)
DEGREE WATER TEMPERATURE AT THE SOUTH BUOY. THEREFORE...DELTA T`S
SHOULD END UP VERY FAVORABLE AROUND 19 DEGREES C. IN ADDITION...DEEP
LAKE INDUCED INSTABILITY IS STILL EXPECTED...WITH EQUILIBRIUM LEVELS
LIKELY TO REACH OR EVEN EXCEED 16,000 FT AGL. THEREFORE...THE THREAT
FOR THUNDER AND LIGHTNING HAS NOT CHANGED...WITH CONVECTIVE
PROCESSES
LIKELY TO BE MORE THAN DEEP ENOUGH THROUGH THE -10 TO -20 LAYER TO
RESULT IN GOOD CHARGE SEPARATION.

IT LOOKS AS THOUGH THIS LAKE EFFECT BAND COULD BEGIN TO SET UP
ACROSS NORTHWESTERN INDIANA AND PERHAPS PORTIONS OF SOUTHEASTERN
COOK COUNTY BY LATE FRIDAY MORNING. HI RES GUIDANCE SUGGESTS
UNCERTAINTY ON THE EXACT AREAS THAT WILL GET THIS LAKE EFFECT
BANDING. SOME HAVE HINTED IN A FARTHER WEST BAND...WHICH WOULD
IMPACT MORE OF THE CHICAGO AREA. HOWEVER...I THINK AT THIS POINT
AREAS IN NORTHWEST INDIANA WILL BE MORE FAVORED...WITH THE
LIKELIHOOD OF A NEARLY DUE NORTH BOUNDARY LAYER FLOW SETTING UP OVER
LAKE MICHIGAN. THIS WOULD TEND TO FAVOR BETTER BOUNDARY LAYER
CONVERGENCE ALONG THE SOUTHERN TIP OF LAKE MICHIGAN FRIDAY
AFTERNOON...WHICH SUGGESTS THAT PORTER AND LAKE INDIANA WILL BE MORE
IN LINE WITH THE POTENTIAL HEAVIER PRECIPITATION. DUE TO THE STRONG
WINDS...IT IS ALSO LIKELY THAT THIS LAKE EFFECT PRECIP COULD BE
DRIVEN WELL INLAND ACROSS NORTHWESTERN INDIANA...POSSIBLY IMPACTING
MUCH OF JASPER AND PORTER COUNTIES AS WELL.

UNCERTAINTY IN PRECIPITATION TYPE IS STILL SOMEWHAT HIGH...AS
SOME WARMER AIR MOVING OFF THE LAKE SHOULD MAKE BOUNDARY LAYER
TEMPERATURES MARGINAL FOR SNOW TO REACH THE SURFACE. HOWEVER...WITH
THE AFOREMENTIONED CONVECTIVE INSTABILITY AND THE GOOD POTENTIAL FOR
SOME HEAVIER PRECIP RATES...IT IS VERY MUCH IN THE REALM OF
POSSIBILITIES THAT ENHANCED DYNAMIC COOLING COULD RESULT IN A COLD
ENOUGH BOUNDARY LAYER SUPPORTIVE OF HEAVY SNOW. IT APPEARS THAT
AREAS INLAND FROM THE IMMEDIATE LAKE SHORE WOULD HAVE THE BEST
POTENTIAL FOR SNOW...THOUGH EVEN AREAS ALONG THE LAKE COULD CHANGE
OVER/MIX WITH SNOW. OVERALL...WITH THE POTENTIAL FOR SOME HEAVIER
BANDS OF SNOW WITH SOME ACCUMULATIONS POSSIBLE (POSSIBLY A FEW
INCHES IN SOME AREAS) ALONG WITH THE VERY STRONG NORTHERLY
WINDS...WE HAVE CHOSEN TO ISSUE THE WINTER WEATHER ADVISORY FOR THE
4 NORTHWESTERN INDIANA COUNTIES. IF...HOWEVER...THE TRANSITION TO
SNOW DOES NOT PAN OUT AS CURRENT THINKING SUGGESTS...WINDS WOULD BE
THE MAIN HAZARD ON FRIDAY...AND THE WINTER WEATHER ADVISORY COULD
THEN BE REPLACED WITH A WIND ADVISORY. THEREFORE...IN SPITE OF THE
UNCERTAINTIES ON WHEN CHANGE OVERS TO SNOW WILL OCCUR AND HOW MUCH
SNOW WILL ACTUALLY FALL...WE FEEL AT THIS POINT...TO ERROR ON THE
SIDE OF CAUTION...AS THERE IS A POTENTIAL FOR SOME VERY HEAVY SNOW
IN ADDITION TO THE STRONG WINDS.

THE WINDS ARE EXPECTED TO GRADUALLY VEER MORE NORTHEASTERLY FRIDAY
NIGHT...AND THIS COULD ALLOW SOME OF THE LAKE EFFECT PRECIPITATION
TO GET INTO NORTHEASTERN ILLINOIS FOR A BRIEF PERIOD FRIDAY EVENING.
HOWEVER...MODEL GUIDANCE CONTINUES TO SUGGEST THAT INVERSION HEIGHTS
WILL CRASH IN A HURRY BY LATE FRIDAY EVENING AS HEIGHTS AND
TEMPERATURES BEGIN TO RISE ALOFT. THEREFORE...ANY SNOW SHOWERS THAT
GET INTO NORTHEASTERN ILLINOIS WOULD LIKELY BE LIGHT AND COME TO AN
END LATE FRIDAY NIGHT/EARLY SAT MORNING.

HIGH TEMPERATURES AREA-WIDE LOOK TO REMAIN IN THE LOWER 40S AT BEST
ON FRIDAY AND SATURDAY

LONG TERM...SUNDAY THROUGH WEDNESDAY...

HIGH TEMPERATURES WILL MODERATE INTO EARLY NEXT WEEK AS THE
WESTERN CONUS UPPER RIDGE BUILDS EASTWARD OVER THE REGION. ANOTHER
COLD FRONT LOOKS TO TAKE AIM ON THE AREA AROUND NEXT
TUESDAY...WHICH WILL RESULT IN OUR NEXT CHANCE OF SHOWERS.
OTHERWISE TEMPERATURES LOOK TO REMAIN NEAR NORMAL DURING THE LATER
HALF OF THE WEEK.

KJB

&&

.AVIATION...

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

* NO ISSUES IN THE NEAR TERM.

* SOUTHWEST WINDS SHIFTING TO THE NORTHWEST WITH FROPA
  TONIGHT...WITH GUSTS INCREASING THROUGH MIDDAY FRIDAY WHILE
  BECOMING MORE NORTHERLY.

* CHANCE OF -SHRA/-SHSN TONIGHT THROUGH EARLY FRIDAY MORNING.

* MVFR CEILINGS LATE TONIGHT INTO FRIDAY MORNING.

RODRIGUEZ/CMS

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

RELATIVELY QUIET CONDITIONS EARLY THIS AFTERNOON WILL CONTINUE THIS
AFTERNOON...WHILE SOUTHWEST WINDS PREVAIL AND MID/HIGH LEVEL CLOUD
COVER CONTINUE TO STREAM OVERHEAD. CONDITIONS WILL BEGIN
DETERIORATING TONIGHT AS SYSTEM/FRONT PUSH THROUGH THE REGION. THE
CURRENT SOUTHWEST WINDS WILL TURN WEST AND NORTHWEST TONIGHT WITH
WIND SPEED/GUSTS QUICKLY INCREASING. LOWERING CEILINGS TO MVFR WILL
ALSO OCCUR WITH THE ARRIVAL OF THIS WIND SHIFT...LIKELY PERSISTING
FOR MUCH OF FRIDAY MORNING. MOISTURE WILL ALSO BE SUFFICIENT FOR
RAIN SHOWERS TO INITIALLY BE POSSIBLE BUT WITH MUCH COLDER AIR
QUICKLY FILTERING IN...SNOW SHOWERS WILL THEN BE POSSIBLE. EXPECT
THESE RAIN/SNOW SHOWERS TO BE ON THE LIGHTER SIDE...WITH NO VIS
RESTRICTION EXPECTED AS WELL AS NO SNOW ACCUMULATION. THE WINDS WILL
CONTINUE TO SHIFT MORE NORTHERLY FRIDAY MORNING AND LIKELY REMAIN IN
THIS NORTH DIRECTION FOR MUCH OF FRIDAY. THIS ORIENTATION WILL
COINCIDE WITH VERY STRONG WINDS...WITH GUSTS ANTICIPATED TO BE
AROUND 40 KT. CONDITIONS SHOULD BE BACK TO VFR FOR THE REMAINDER OF
THE DAY/FORECAST PERIOD...BUT A TREND BACK TOWARDS DETERIORATING
CONDITIONS COULD BE POSSIBLE IF LAKE EFFECT PRECIP AND CLOUD COVER
MOVE TOWARDS THE TERMINALS FRIDAY EVENING.

RODRIGUEZ

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

* HIGH CONFIDENCE OF VFR CONDITIONS IN THE NEAR TERM.

* HIGH CONFIDENCE OF WIND DIRECTION AND SPEED/GUSTS...MEDIUM HIGH
  CONFIDENCE OF EXACT TIMING OF FROPA.

* HIGH CONFIDENCE OF -SHRA/-SHSN...MEDIUM CONFIDENCE OF DURATION.

* HIGH CONFIDENCE OF MVFR CEILINGS...MEDIUM CONFIDENCE OF DURATION.

RODRIGUEZ/CMS

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

* FRIDAY NIGHT...STRONG NORTH WINDS GUSTING TO 30 KT. CHANCE OF
  SHRA OR SHSN.

* SATURDAY...VFR. WX NIL. NORTHEAST WINDS 10-15KT.

* SUNDAY...VFR. WX NIL. SOUTH WINDS.

* MONDAY...CHANCE OF SHRA. GUSTY SOUTHERLY WINDS.

* TUESDAY...CHANCE OF SHRA. WESTERLY WINDS.

* WEDNESDAY...VFR. WX NIL. SOUTHWEST WINDS.

&&

.MARINE...
250 PM CDT

A VERY ACTIVE PERIOD OVER LAKE MICHIGAN BEGINNING LATER TONIGHT. THE
AREA WILL FIND ITSELF IN A FAVORABLE AND ANOMALOUS SYNOPTIC WEATHER
PATTERN FOR STRONG NORTHERLY WINDS...AND THIS WILL BE FURTHER AIDED
BY THE WARM WATERS/EXTREME INSTABILITY TO PRODUCE REGULAR HIGHER END
STORM FORCE GUSTS PERSISTING INTO FRIDAY. A STRONG COLD FRONT WILL
MOVE DOWN THE LAKE RAPIDLY FROM AROUND MIDNIGHT THROUGH 5 AM.
IMMEDIATELY BEHIND THIS A VERY TIGHT PRESSURE GRADIENT IN SYNC WITH
COLD AIR ADVECTION WILL PRODUCE A RAMP UP IN NORTHERLY WIND SPEEDS.
THE HIGHEST WIND SPEEDS OF STORM FORCE TO 50 AND POSSIBLY EVEN 55 KT
ARE EXPECTED LATE TONIGHT THROUGH MID FRIDAY AFTERNOON FOR THE
CENTRAL AND SOUTHERN PART OF THE LAKE...AND AFTER DAYBREAK THROUGH
THE DAY ON FRIDAY FOR THE NEARSHORE AREAS OF ILLINOIS AND INDIANA.
THE WAVE MAXIMUM OF OVER 20 FOOTERS IS EXPECTED TO DEVELOP OVER THE
CENTRAL PART OF THE LAKE EARLY FRIDAY MORNING AND EVOLVE SOUTHWARD
REACHING THE ILLINOIS AND INDIANA NEARSHORE FRIDAY AFTERNOON AND
EARLY EVENING. WAVES WILL BE VERY SLOW TO SUBSIDE THROUGH LATE
FRIDAY NIGHT AND EARLY SATURDAY. HIGH PRESSURE WILL MOVE QUICKLY
OVER THE LAKE SATURDAY NIGHT BEFORE SOUTHERLY FLOW RETURNS TO THE
LAKE.

MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WIND ADVISORY...ILZ014...7 AM FRIDAY TO 10 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022...7
AM
     FRIDAY TO 7 PM FRIDAY.

     WIND ADVISORY...ILZ023-ILZ033...10 AM FRIDAY TO 7 PM FRIDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011...10 AM
     FRIDAY TO 10 PM FRIDAY.

     WIND ADVISORY...INZ019...10 AM FRIDAY TO 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 PM FRIDAY TO
     4 AM SATURDAY.

     STORM WARNING...
LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
     LMZ878...3 AM FRIDAY TO 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563...1 AM FRIDAY TO 10
     PM FRIDAY.

     GALE WARNING...LMZ740...4 AM FRIDAY TO 4 AM SATURDAY.

     STORM WARNING...LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...4 AM
FRIDAY
     TO 7 PM FRIDAY.

&&

$$

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

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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000
FXUS63 KLOT 302320
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
506 PM CDT THU OCT 30 2014

.UPDATE...

EARLY EVENING UPDATE...

MADE A FEW ADJUSTMENTS TO FORECAST TO INCREASE POPS ACROSS SOUTHERN
CWA WHERE WEST-EAST BAND OF MODERATE RAIN HAD DEVELOPED LATE IN THE
AFTERNOON...AND TO SLOW ARRIVAL OF POPS ACROSS THE NORTHERN COUNTIES
A BIT IN LINE WITH VARIOUS HIGH-RES NEAR TERM MODELS WITH APPROACH
OF COLD FRONT LATER THIS EVENING.

RAIN BAND ACROSS LIVINGSTON...FORD IROQUOIS AND BENTON COUNTIES
APPEARS TO BE ASSOCIATED WITH MID-LEVEL FRONTOGENETICAL FORCING WITH
INITIAL SHORT WAVE PROPAGATING SOUTHEAST ACROSS MO/IL INTO THE LOWER
OH AND TENNESSEE VALLEYS. THIS SHOULD SCOOT OFF TO THE SOUTHEAST
OVER THE NEXT COUPLE OF HOURS. FARTHER NORTHWEST...COLD FRONT WAS
DEVELOPING SOUTHEASTWARD ACROSS SOUTHEAST MINNESOTA AND
NORTHWEST/WESTERN WISCONSIN IN RESPONSE TO STRENGTHENING PRESSURE
RISES WITH STRONG HIGH BUILDING SOUTHEAST FROM CANADA. LITTLE IN
RADAR DETECTABLE PRECIP OCCURRING ACROSS THOSE AREAS AT THIS TIME
THUS HAVE SLOWED ARRIVAL AND SLIGHTLY LOWERED POPS FOR SHOWERS
ACROSS NORTHERN IL DURING THE EARLY EVENING HOURS...MORE ALONG THE
CONCENSUS OF THE RAP/HRRR/LOCAL ARW AND EVEN MANY OF THE SYNOPTIC
SCALE MODELS WHICH HOLD MEASURABLE PRECIP OFF LARGELY UNTIL MIDNIGHT
OR AFTER.

RATZER

PREVIOUS DISCUSSION FROM 332 PM CDT...

SHORT TERM...TONIGHT THROUGH SATURDAY...
THE MAIN FORECAST FOCUS THIS AFTERNOON CONTINUES TO CENTER AROUND
THE STORM SYSTEM EXPECTED IMPACT THE REGION LATE TONIGHT THROUGH
FRIDAY NIGHT. STRONG WINDS...AND THE POTENTIAL FOR SOME PERIODS OF
HEAVY LAKE EFFECT SNOW ARE THE PRIMARY CONCERNS.

WE ARE ISSUING A WIND ADVISORY FOR MOST OF THE EASTERN HALF OF THE
AREA...WITH THE EXCEPTION OF LAKE...PORTER...JASPER AND NEWTON
COUNTIES IN INDIANA...WHERE A WINTER WEATHER ADVISORY IS BEING
ISSUED. SEE BELOW FOR MORE DETAILS.

WATER VAPOR IMAGERY EARLY THIS AFTERNOON SHOWS A RATHER VIGOROUS
UPPER LEVEL IMPULSE NOW MOVING JUST EAST OF LAKE WINNIPEG AND OVER
FAR SOUTHWESTERN ONTARIO. THIS WAVE IS EXPECTED TO CONTINUE DIGGING
SOUTH-SOUTHEASTWARD TONIGHT ALONG THE EASTERN PERIPHERY OF AN UPPER
RIDGE...CURRENT CENTERED ACROSS THE INTER MOUNTAIN WEST. AS THIS
OCCURS...AN AREA OF SURFACE LOW PRESSURE WILL SHIFT SOUTHWARD ACROSS
LOWER MICHIGAN INTO FRIDAY MORNING. FARTHER NORTHWEST...A RATHER
STOUT 1036 MB HIGH IS ALSO EXPECTED TO RAPIDLY BUILD SOUTHEASTWARD
ACROSS THE DAKOTAS AND UPPER MIDWEST INTO FRIDAY. THIS STILL LOOKS
TO SET THE STAGE FOR STRONG NORTHERN WINDS ACROSS THE AREA DURING
THE DAY FRIDAY AS STRONG PRESSURE RISES AND STRONG COLD AIR
ADVECTION LEAD TO A QUICK RAMP UP OF NORTHERLY WINDS IN THE WAKE OF
A COLD FRONTAL PASSAGE LATE TONIGHT. MODEL SOUNDINGS ALL SUGGEST
MEAN MIXING LAYER WIND SPEEDS COULD TOP 40 KT ACROSS MAINLY THE
EASTERN HALF OF THE AREA INLAND FROM THE LAKE...MEANING WIND GUSTS
COULD EASILY REACH THIS MAGNITUDE IN MOST AREAS. HOWEVER...AREAS
DIRECTLY ADJACENT TO LAKE MICHIGAN IN NORTHEASTERN ILLINOIS AND
NORTHWESTERN INDIANA COULD EXPERIENCE EVEN STRONGER GUSTS UP AROUND
50 KT WITH THE STRONG NORTHERLY ONSHORE COMPONENT TO THE WINDS.
WINDS LOOK TO REMAIN INTO THE EVENING ON HALLOWEEN...THOUGH WIND
SPEEDS SHOULD GRADUALLY WEAKEN THROUGH THE NIGHT.

THE LAKE SHORE FLOOD ADVISORY WILL CONTINUE FOR AREAS NEAR THE LAKE
AS LARGE BATTERING WAVES IN EXCESS OF 20 FT APPEAR LIKELY...AND AS
THE PREVIOUS DISCUSSION MENTIONED...LAKE LEVELS ARE ABOUT 2 FT
HIGHER THAN PAST YEARS...WHICH COULD MAKE THE IMPACTS OF THESE WAVES
HIGHER THEN SIMILAR WAVE EVENTS IN THE PAST COUPLE OF YEARS.

DUE TO THE LIKELIHOOD OF THESE STRONG WINDS...WE HAVE ISSUED A WIND
ADVISORY FOR MUCH OF THE EASTERN HALF OF MY CWA. THIS
INCLUDES AREAS BASICALLY ALONG AND EAST OF A LINE FROM HARVARD
SOUTHWARD THROUGH KANKAKEE AND IROQUOIS COUNTIES. THE ONLY EXCEPTION
TO THIS WIND ADVISORY IS FOR LAKE COUNTY INDIANA...AS WELL AS
PORTER...JASPER AND NEWTON COUNTIES...WHERE A WINTER WEATHER
ADVISORY IS BEING ISSUED IN PLACE OF A WIND ADVISORY FOR THE
COMBINATION OF THESE STRONG WINDS AND ALSO THE INCREASING POTENTIAL
FOR SOME ACCUMULATING LAKE EFFECT SNOW ON FRIDAY INTO FRIDAY
EVENING.

PRECIPITATION WITH THE APPROACHING COLD FRONT AND UPPER LEVEL
IMPULSE
WILL LIKELY BEGIN TO ENTER FAR NORTHERN ILLINOIS AFTER 10 PM THIS
EVENING...AND BE IN THE FORM OF RAIN SHOWERS. THIS INITIAL ROUND OF
SHOWERS SHOULD MOVE SOUTHWARD ACROSS THE AREA THROUGH THE NIGHT...IN
CLOSE PROXIMITY THE INCREASING FRONTOGENESIS IN THE VICINITY OF THE
COLD FRONTAL BOUNDARY. THIS SHOULD BE A FAIRLY PROGRESSIVE AREA OF
SHOWERS...WITH MOST AREAS ACROSS NORTH CENTRAL ILLINOIS DRYING OUT
BY EARLY FRIDAY MORNING.

THE SECOND STAGE OF PRECIPITATION WILL BE MORE OF A TRUE LAKE EFFECT
SETUP. A COLD AIRMASS FEATURING -7 DEGREE C TEMPERATURES AT 850 MB
WILL MOVE OVER THE LAKE...WHICH IS CURRENTLY REPORTING A 53F (11.7C)
DEGREE WATER TEMPERATURE AT THE SOUTH BUOY. THEREFORE...DELTA T`S
SHOULD END UP VERY FAVORABLE AROUND 19 DEGREES C. IN ADDITION...DEEP
LAKE INDUCED INSTABILITY IS STILL EXPECTED...WITH EQUILIBRIUM LEVELS
LIKELY TO REACH OR EVEN EXCEED 16,000 FT AGL. THEREFORE...THE THREAT
FOR THUNDER AND LIGHTNING HAS NOT CHANGED...WITH CONVECTIVE
PROCESSES
LIKELY TO BE MORE THAN DEEP ENOUGH THROUGH THE -10 TO -20 LAYER TO
RESULT IN GOOD CHARGE SEPARATION.

IT LOOKS AS THOUGH THIS LAKE EFFECT BAND COULD BEGIN TO SET UP
ACROSS NORTHWESTERN INDIANA AND PERHAPS PORTIONS OF SOUTHEASTERN
COOK COUNTY BY LATE FRIDAY MORNING. HI RES GUIDANCE SUGGESTS
UNCERTAINTY ON THE EXACT AREAS THAT WILL GET THIS LAKE EFFECT
BANDING. SOME HAVE HINTED IN A FARTHER WEST BAND...WHICH WOULD
IMPACT MORE OF THE CHICAGO AREA. HOWEVER...I THINK AT THIS POINT
AREAS IN NORTHWEST INDIANA WILL BE MORE FAVORED...WITH THE
LIKELIHOOD OF A NEARLY DUE NORTH BOUNDARY LAYER FLOW SETTING UP OVER
LAKE MICHIGAN. THIS WOULD TEND TO FAVOR BETTER BOUNDARY LAYER
CONVERGENCE ALONG THE SOUTHERN TIP OF LAKE MICHIGAN FRIDAY
AFTERNOON...WHICH SUGGESTS THAT PORTER AND LAKE INDIANA WILL BE MORE
IN LINE WITH THE POTENTIAL HEAVIER PRECIPITATION. DUE TO THE STRONG
WINDS...IT IS ALSO LIKELY THAT THIS LAKE EFFECT PRECIP COULD BE
DRIVEN WELL INLAND ACROSS NORTHWESTERN INDIANA...POSSIBLY IMPACTING
MUCH OF JASPER AND PORTER COUNTIES AS WELL.

UNCERTAINTY IN PRECIPITATION TYPE IS STILL SOMEWHAT HIGH...AS
SOME WARMER AIR MOVING OFF THE LAKE SHOULD MAKE BOUNDARY LAYER
TEMPERATURES MARGINAL FOR SNOW TO REACH THE SURFACE. HOWEVER...WITH
THE AFOREMENTIONED CONVECTIVE INSTABILITY AND THE GOOD POTENTIAL FOR
SOME HEAVIER PRECIP RATES...IT IS VERY MUCH IN THE REALM OF
POSSIBILITIES THAT ENHANCED DYNAMIC COOLING COULD RESULT IN A COLD
ENOUGH BOUNDARY LAYER SUPPORTIVE OF HEAVY SNOW. IT APPEARS THAT
AREAS INLAND FROM THE IMMEDIATE LAKE SHORE WOULD HAVE THE BEST
POTENTIAL FOR SNOW...THOUGH EVEN AREAS ALONG THE LAKE COULD CHANGE
OVER/MIX WITH SNOW. OVERALL...WITH THE POTENTIAL FOR SOME HEAVIER
BANDS OF SNOW WITH SOME ACCUMULATIONS POSSIBLE (POSSIBLY A FEW
INCHES IN SOME AREAS) ALONG WITH THE VERY STRONG NORTHERLY
WINDS...WE HAVE CHOSEN TO ISSUE THE WINTER WEATHER ADVISORY FOR THE
4 NORTHWESTERN INDIANA COUNTIES. IF...HOWEVER...THE TRANSITION TO
SNOW DOES NOT PAN OUT AS CURRENT THINKING SUGGESTS...WINDS WOULD BE
THE MAIN HAZARD ON FRIDAY...AND THE WINTER WEATHER ADVISORY COULD
THEN BE REPLACED WITH A WIND ADVISORY. THEREFORE...IN SPITE OF THE
UNCERTAINTIES ON WHEN CHANGE OVERS TO SNOW WILL OCCUR AND HOW MUCH
SNOW WILL ACTUALLY FALL...WE FEEL AT THIS POINT...TO ERROR ON THE
SIDE OF CAUTION...AS THERE IS A POTENTIAL FOR SOME VERY HEAVY SNOW
IN ADDITION TO THE STRONG WINDS.

THE WINDS ARE EXPECTED TO GRADUALLY VEER MORE NORTHEASTERLY FRIDAY
NIGHT...AND THIS COULD ALLOW SOME OF THE LAKE EFFECT PRECIPITATION
TO GET INTO NORTHEASTERN ILLINOIS FOR A BRIEF PERIOD FRIDAY EVENING.
HOWEVER...MODEL GUIDANCE CONTINUES TO SUGGEST THAT INVERSION HEIGHTS
WILL CRASH IN A HURRY BY LATE FRIDAY EVENING AS HEIGHTS AND
TEMPERATURES BEGIN TO RISE ALOFT. THEREFORE...ANY SNOW SHOWERS THAT
GET INTO NORTHEASTERN ILLINOIS WOULD LIKELY BE LIGHT AND COME TO AN
END LATE FRIDAY NIGHT/EARLY SAT MORNING.

HIGH TEMPERATURES AREA-WIDE LOOK TO REMAIN IN THE LOWER 40S AT BEST
ON FRIDAY AND SATURDAY

LONG TERM...SUNDAY THROUGH WEDNESDAY...

HIGH TEMPERATURES WILL MODERATE INTO EARLY NEXT WEEK AS THE
WESTERN CONUS UPPER RIDGE BUILDS EASTWARD OVER THE REGION. ANOTHER
COLD FRONT LOOKS TO TAKE AIM ON THE AREA AROUND NEXT
TUESDAY...WHICH WILL RESULT IN OUR NEXT CHANCE OF SHOWERS.
OTHERWISE TEMPERATURES LOOK TO REMAIN NEAR NORMAL DURING THE LATER
HALF OF THE WEEK.

KJB

&&

.AVIATION...

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

* NO ISSUES IN THE NEAR TERM.

* SOUTHWEST WINDS SHIFTING TO THE NORTHWEST WITH FROPA
  TONIGHT...WITH GUSTS INCREASING THROUGH MIDDAY FRIDAY WHILE
  BECOMING MORE NORTHERLY.

* CHANCE OF -SHRA/-SHSN TONIGHT THROUGH EARLY FRIDAY MORNING.

* MVFR CEILINGS LATE TONIGHT INTO FRIDAY MORNING.

RODRIGUEZ/CMS

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

RELATIVELY QUIET CONDITIONS EARLY THIS AFTERNOON WILL CONTINUE THIS
AFTERNOON...WHILE SOUTHWEST WINDS PREVAIL AND MID/HIGH LEVEL CLOUD
COVER CONTINUE TO STREAM OVERHEAD. CONDITIONS WILL BEGIN
DETERIORATING TONIGHT AS SYSTEM/FRONT PUSH THROUGH THE REGION. THE
CURRENT SOUTHWEST WINDS WILL TURN WEST AND NORTHWEST TONIGHT WITH
WIND SPEED/GUSTS QUICKLY INCREASING. LOWERING CEILINGS TO MVFR WILL
ALSO OCCUR WITH THE ARRIVAL OF THIS WIND SHIFT...LIKELY PERSISTING
FOR MUCH OF FRIDAY MORNING. MOISTURE WILL ALSO BE SUFFICIENT FOR
RAIN SHOWERS TO INITIALLY BE POSSIBLE BUT WITH MUCH COLDER AIR
QUICKLY FILTERING IN...SNOW SHOWERS WILL THEN BE POSSIBLE. EXPECT
THESE RAIN/SNOW SHOWERS TO BE ON THE LIGHTER SIDE...WITH NO VIS
RESTRICTION EXPECTED AS WELL AS NO SNOW ACCUMULATION. THE WINDS WILL
CONTINUE TO SHIFT MORE NORTHERLY FRIDAY MORNING AND LIKELY REMAIN IN
THIS NORTH DIRECTION FOR MUCH OF FRIDAY. THIS ORIENTATION WILL
COINCIDE WITH VERY STRONG WINDS...WITH GUSTS ANTICIPATED TO BE
AROUND 40 KT. CONDITIONS SHOULD BE BACK TO VFR FOR THE REMAINDER OF
THE DAY/FORECAST PERIOD...BUT A TREND BACK TOWARDS DETERIORATING
CONDITIONS COULD BE POSSIBLE IF LAKE EFFECT PRECIP AND CLOUD COVER
MOVE TOWARDS THE TERMINALS FRIDAY EVENING.

RODRIGUEZ

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

* HIGH CONFIDENCE OF VFR CONDITIONS IN THE NEAR TERM.

* HIGH CONFIDENCE OF WIND DIRECTION AND SPEED/GUSTS...MEDIUM HIGH
  CONFIDENCE OF EXACT TIMING OF FROPA.

* HIGH CONFIDENCE OF -SHRA/-SHSN...MEDIUM CONFIDENCE OF DURATION.

* HIGH CONFIDENCE OF MVFR CEILINGS...MEDIUM CONFIDENCE OF DURATION.

RODRIGUEZ/CMS

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

* FRIDAY NIGHT...STRONG NORTH WINDS GUSTING TO 30 KT. CHANCE OF
  SHRA OR SHSN.

* SATURDAY...VFR. WX NIL. NORTHEAST WINDS 10-15KT.

* SUNDAY...VFR. WX NIL. SOUTH WINDS.

* MONDAY...CHANCE OF SHRA. GUSTY SOUTHERLY WINDS.

* TUESDAY...CHANCE OF SHRA. WESTERLY WINDS.

* WEDNESDAY...VFR. WX NIL. SOUTHWEST WINDS.

&&

.MARINE...
250 PM CDT

A VERY ACTIVE PERIOD OVER LAKE MICHIGAN BEGINNING LATER TONIGHT. THE
AREA WILL FIND ITSELF IN A FAVORABLE AND ANOMALOUS SYNOPTIC WEATHER
PATTERN FOR STRONG NORTHERLY WINDS...AND THIS WILL BE FURTHER AIDED
BY THE WARM WATERS/EXTREME INSTABILITY TO PRODUCE REGULAR HIGHER END
STORM FORCE GUSTS PERSISTING INTO FRIDAY. A STRONG COLD FRONT WILL
MOVE DOWN THE LAKE RAPIDLY FROM AROUND MIDNIGHT THROUGH 5 AM.
IMMEDIATELY BEHIND THIS A VERY TIGHT PRESSURE GRADIENT IN SYNC WITH
COLD AIR ADVECTION WILL PRODUCE A RAMP UP IN NORTHERLY WIND SPEEDS.
THE HIGHEST WIND SPEEDS OF STORM FORCE TO 50 AND POSSIBLY EVEN 55 KT
ARE EXPECTED LATE TONIGHT THROUGH MID FRIDAY AFTERNOON FOR THE
CENTRAL AND SOUTHERN PART OF THE LAKE...AND AFTER DAYBREAK THROUGH
THE DAY ON FRIDAY FOR THE NEARSHORE AREAS OF ILLINOIS AND INDIANA.
THE WAVE MAXIMUM OF OVER 20 FOOTERS IS EXPECTED TO DEVELOP OVER THE
CENTRAL PART OF THE LAKE EARLY FRIDAY MORNING AND EVOLVE SOUTHWARD
REACHING THE ILLINOIS AND INDIANA NEARSHORE FRIDAY AFTERNOON AND
EARLY EVENING. WAVES WILL BE VERY SLOW TO SUBSIDE THROUGH LATE
FRIDAY NIGHT AND EARLY SATURDAY. HIGH PRESSURE WILL MOVE QUICKLY
OVER THE LAKE SATURDAY NIGHT BEFORE SOUTHERLY FLOW RETURNS TO THE
LAKE.

MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WIND ADVISORY...ILZ014...7 AM FRIDAY TO 10 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022...7
AM
     FRIDAY TO 7 PM FRIDAY.

     WIND ADVISORY...ILZ023-ILZ033...10 AM FRIDAY TO 7 PM FRIDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011...10 AM
     FRIDAY TO 10 PM FRIDAY.

     WIND ADVISORY...INZ019...10 AM FRIDAY TO 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 PM FRIDAY TO
     4 AM SATURDAY.

     STORM WARNING...
LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
     LMZ878...3 AM FRIDAY TO 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563...1 AM FRIDAY TO 10
     PM FRIDAY.

     GALE WARNING...LMZ740...4 AM FRIDAY TO 4 AM SATURDAY.

     STORM WARNING...LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...4 AM
FRIDAY
     TO 7 PM FRIDAY.

&&

$$

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

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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000
FXUS63 KILX 302306
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
606 PM CDT Thu Oct 30 2014

.SHORT TERM...(Tonight)
ISSUED AT 300 PM CDT THU OCT 30 2014

Two waves impacting the short term.  The first low is over western
Missouri and weak lift associated with weak frontogenesis sparking
some showers for the region.  Plenty of dry air in the area is also
helping to erode the showers and keep them more scattered in
nature.  Cooler air on the way, with another shot of cold air
deepening the trof aloft with the next wave later this evening.
This second wave acting a bit more like a cold front with the wind
shift to more north/northwesterly winds tonight and cold air, but
the models are having a hard time with precip.  Current precip is
overblown in the models, and the later wave (after midnight) is even
more sketchy with QPF.  As a result, pops are minimal in association
with the second wave...and instead follow the progression of the
current precip out to the east by midnight. Temps currently on the
cooler side of guidance as the temps have not dropped far enough in
the last 24 hours and that trend may continue, though the RH will be
plenty for clouds, if not for ongoing precip. Tightening pressure
gradient behind the boundary resulting in winds ramping up in the
early morning hours in advance of a blustery cold day.

&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 300 PM CDT THU OCT 30 2014

A vigorous cold Canadian shortwave will drop southward into the
Midwest by Friday morning. A strong cold front with this feature
will usher in much colder air to central Illinois for Friday, with
highs only reaching the 40s. North-northwest winds 20-30 mph with
gusts 35-40 mph will develop along and behind the cold front,
bringing wind chills into the 30s for the afternoon. Little
precipitation will remain behind the front, however slight chances
will remain near the IL/IN border. Forecast soundings in this area
indicate wet bulb temperatures below freezing to ground level below
the precipitation generation level, and this should allow for light
snow or mixed rain and snow reaching the ground Friday afternoon and
evening. Breezy and cold conditions will continue into the evening
for Halloween Trick or Treat conditions with temperatures dropping
quickly into the 30s and wind chill values into the 20s.

Friday night, light north winds will continue, while the cold air
mass results in temperatures reaching 25-30 degrees for the first
widespread freeze of the season. Have issued a freeze warning to
account for this.

Little warming is expected through Sunday morning, with another
freezing night expected. A mild and moist southwesterly low level
flow will develop late in the weekend through early next week as an
upper level ridge shifts eastward across Illinois and a deep trough
crosses the Rockies. This trough will bring good chances of showers
late Monday through tuesday night as the system moves into the Ohio
river valley. Isolated thunderstorms may also occur Monday night and
Tue south of I-72. Drier weather is expected Wed night and Thu as
dry northwesterly flow trails the system.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 605 PM CDT THU OCT 30 2014

Low VFR cigs expected thru the evening hours and then will have to
watch for the possibility for at least a brief period of MVFR cigs
with a cold frontal passage after 07z tonight with the main concern
after that being strong northerly winds on Friday. First batch of
rain tracking south-southeast across the area early this evening
and will continue with tempo groups over mainly the eastern TAF
sites for a few hours early this evening. We will probably see a
brief break in any precip chances later this evening before a much
stronger wave shifts south into the lower Great Lakes bringing
another threat for scattered showers and a wind shift into the
north at all TAF sites in the 07z-10z time frame. This is the time
frame where we may see a brief period of MVFR cigs but for now,
will only include a scattered group around 2500 feet. Once the
front shifts south of our area, surface winds will increase to
between 20 and 30 kts by mid morning with gusts to around 35 kts
at times.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING from Midnight Friday Night to 9 AM CDT Saturday
FOR ILZ027>031-036>038-040>057-061>063-066>068-071>073.

&&

$$

SHORT TERM...HJS
LONG TERM...Onton
AVIATION...Smith





000
FXUS63 KLOT 302206
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
506 PM CDT THU OCT 30 2014

.DISCUSSION...

SHORT TERM...TONIGHT THROUGH SATURDAY...
THE MAIN FORECAST FOCUS THIS AFTERNOON CONTINUES TO CENTER AROUND
THE STORM SYSTEM EXPECTED IMPACT THE REGION LATE TONIGHT THROUGH
FRIDAY NIGHT. STRONG WINDS...AND THE POTENTIAL FOR SOME PERIODS OF
HEAVY LAKE EFFECT SNOW ARE THE PRIMARY CONCERNS.

WE ARE ISSUING A WIND ADVISORY FOR MOST OF THE EASTERN HALF OF THE
AREA...WITH THE EXCEPTION OF LAKE...PORTER...JASPER AND NEWTON
COUNTIES IN INDIANA...WHERE A WINTER WEATHER ADVISORY IS BEING
ISSUED. SEE BELOW FOR MORE DETAILS.

WATER VAPOR IMAGERY EARLY THIS AFTERNOON SHOWS A RATHER VIGOROUS
UPPER LEVEL IMPULSE NOW MOVING JUST EAST OF LAKE WINNIPEG AND OVER
FAR SOUTHWESTERN ONTARIO. THIS WAVE IS EXPECTED TO CONTINUE DIGGING
SOUTH-SOUTHEASTWARD TONIGHT ALONG THE EASTERN PERIPHERY OF AN UPPER
RIDGE...CURRENT CENTERED ACROSS THE INTER MOUNTAIN WEST. AS THIS
OCCURS...AN AREA OF SURFACE LOW PRESSURE WILL SHIFT SOUTHWARD ACROSS
LOWER MICHIGAN INTO FRIDAY MORNING. FARTHER NORTHWEST...A RATHER
STOUT 1036 MB HIGH IS ALSO EXPECTED TO RAPIDLY BUILD SOUTHEASTWARD
ACROSS THE DAKOTAS AND UPPER MIDWEST INTO FRIDAY. THIS STILL LOOKS
TO SET THE STAGE FOR STRONG NORTHERN WINDS ACROSS THE AREA DURING
THE DAY FRIDAY AS STRONG PRESSURE RISES AND STRONG COLD AIR
ADVECTION LEAD TO A QUICK RAMP UP OF NORTHERLY WINDS IN THE WAKE OF
A COLD FRONTAL PASSAGE LATE TONIGHT. MODEL SOUNDINGS ALL SUGGEST
MEAN MIXING LAYER WIND SPEEDS COULD TOP 40 KT ACROSS MAINLY THE
EASTERN HALF OF THE AREA INLAND FROM THE LAKE...MEANING WIND GUSTS
COULD EASILY REACH THIS MAGNITUDE IN MOST AREAS. HOWEVER...AREAS
DIRECTLY ADJACENT TO LAKE MICHIGAN IN NORTHEASTERN ILLINOIS AND
NORTHWESTERN INDIANA COULD EXPERIENCE EVEN STRONGER GUSTS UP AROUND
50 KT WITH THE STRONG NORTHERLY ONSHORE COMPONENT TO THE WINDS.
WINDS LOOK TO REMAIN INTO THE EVENING ON HALLOWEEN...THOUGH WIND
SPEEDS SHOULD GRADUALLY WEAKEN THROUGH THE NIGHT.

THE LAKE SHORE FLOOD ADVISORY WILL CONTINUE FOR AREAS NEAR THE LAKE
AS LARGE BATTERING WAVES IN EXCESS OF 20 FT APPEAR LIKELY...AND AS
THE PREVIOUS DISCUSSION MENTIONED...LAKE LEVELS ARE ABOUT 2 FT
HIGHER THAN PAST YEARS...WHICH COULD MAKE THE IMPACTS OF THESE WAVES
HIGHER THEN SIMILAR WAVE EVENTS IN THE PAST COUPLE OF YEARS.

DUE TO THE LIKELIHOOD OF THESE STRONG WINDS...WE HAVE ISSUED A WIND
ADVISORY FOR MUCH OF THE EASTERN HALF OF MY CWA. THIS
INCLUDES AREAS BASICALLY ALONG AND EAST OF A LINE FROM HARVARD
SOUTHWARD THROUGH KANKAKEE AND IROQUOIS COUNTIES. THE ONLY EXCEPTION
TO THIS WIND ADVISORY IS FOR LAKE COUNTY INDIANA...AS WELL AS
PORTER...JASPER AND NEWTON COUNTIES...WHERE A WINTER WEATHER
ADVISORY IS BEING ISSUED IN PLACE OF A WIND ADVISORY FOR THE
COMBINATION OF THESE STRONG WINDS AND ALSO THE INCREASING POTENTIAL
FOR SOME ACCUMULATING LAKE EFFECT SNOW ON FRIDAY INTO FRIDAY
EVENING.

PRECIPITATION WITH THE APPROACHING COLD FRONT AND UPPER LEVEL IMPULSE
WILL LIKELY BEGIN TO ENTER FAR NORTHERN ILLINOIS AFTER 10 PM THIS
EVENING...AND BE IN THE FORM OF RAIN SHOWERS. THIS INITIAL ROUND OF
SHOWERS SHOULD MOVE SOUTHWARD ACROSS THE AREA THROUGH THE NIGHT...IN
CLOSE PROXIMITY THE INCREASING FRONTOGENESIS IN THE VICINITY OF THE
COLD FRONTAL BOUNDARY. THIS SHOULD BE A FAIRLY PROGRESSIVE AREA OF
SHOWERS...WITH MOST AREAS ACROSS NORTH CENTRAL ILLINOIS DRYING OUT BY
EARLY FRIDAY MORNING.

THE SECOND STAGE OF PRECIPITATION WILL BE MORE OF A TRUE LAKE EFFECT
SETUP. A COLD AIRMASS FEATURING -7 DEGREE C TEMPERATURES AT 850 MB
WILL MOVE OVER THE LAKE...WHICH IS CURRENTLY REPORTING A 53F (11.7C)
DEGREE WATER TEMPERATURE AT THE SOUTH BUOY. THEREFORE...DELTA T`S
SHOULD END UP VERY FAVORABLE AROUND 19 DEGREES C. IN ADDITION...DEEP
LAKE INDUCED INSTABILITY IS STILL EXPECTED...WITH EQUILIBRIUM LEVELS
LIKELY TO REACH OR EVEN EXCEED 16,000 FT AGL. THEREFORE...THE THREAT
FOR THUNDER AND LIGHTNING HAS NOT CHANGED...WITH CONVECTIVE PROCESSES
LIKELY TO BE MORE THAN DEEP ENOUGH THROUGH THE -10 TO -20 LAYER TO
RESULT IN GOOD CHARGE SEPARATION.

IT LOOKS AS THOUGH THIS LAKE EFFECT BAND COULD BEGIN TO SET UP
ACROSS NORTHWESTERN INDIANA AND PERHAPS PORTIONS OF SOUTHEASTERN COOK
COUNTY BY LATE FRIDAY MORNING. HI RES GUIDANCE SUGGESTS UNCERTAINTY
ON THE EXACT AREAS THAT WILL GET THIS LAKE EFFECT BANDING. SOME HAVE
HINTED IN A FARTHER WEST BAND...WHICH WOULD IMPACT MORE OF THE
CHICAGO AREA. HOWEVER...I THINK AT THIS POINT AREAS IN NORTHWEST
INDIANA WILL BE MORE FAVORED...WITH THE LIKELIHOOD OF A NEARLY DUE
NORTH BOUNDARY LAYER FLOW SETTING UP OVER LAKE MICHIGAN. THIS WOULD
TEND TO FAVOR BETTER BOUNDARY LAYER CONVERGENCE ALONG THE SOUTHERN
TIP OF LAKE MICHIGAN FRIDAY AFTERNOON...WHICH SUGGESTS THAT PORTER
AND LAKE INDIANA WILL BE MORE IN LINE WITH THE POTENTIAL HEAVIER
PRECIPITATION. DUE TO THE STRONG WINDS...IT IS ALSO LIKELY THAT THIS
LAKE EFFECT PRECIP COULD BE DRIVEN WELL INLAND ACROSS NORTHWESTERN
INDIANA...POSSIBLY IMPACTING MUCH OF JASPER AND PORTER COUNTIES AS
WELL.

UNCERTAINTY IN PRECIPITATION TYPE IS STILL SOMEWHAT HIGH...AS
SOME WARMER AIR MOVING OFF THE LAKE SHOULD MAKE BOUNDARY LAYER
TEMPERATURES MARGINAL FOR SNOW TO REACH THE SURFACE. HOWEVER...WITH
THE AFOREMENTIONED CONVECTIVE INSTABILITY AND THE GOOD POTENTIAL FOR
SOME HEAVIER PRECIP RATES...IT IS VERY MUCH IN THE REALM OF
POSSIBILITIES THAT ENHANCED DYNAMIC COOLING COULD RESULT IN A COLD
ENOUGH BOUNDARY LAYER SUPPORTIVE OF HEAVY SNOW. IT APPEARS THAT
AREAS INLAND FROM THE IMMEDIATE LAKE SHORE WOULD HAVE THE BEST
POTENTIAL FOR SNOW...THOUGH EVEN AREAS ALONG THE LAKE COULD CHANGE
OVER/MIX WITH SNOW. OVERALL...WITH THE POTENTIAL FOR SOME HEAVIER
BANDS OF SNOW WITH SOME ACCUMULATIONS POSSIBLE (POSSIBLY A FEW
INCHES IN SOME AREAS) ALONG WITH THE VERY STRONG NORTHERLY
WINDS...WE HAVE CHOSEN TO ISSUE THE WINTER WEATHER ADVISORY FOR THE
4 NORTHWESTERN INDIANA COUNTIES. IF...HOWEVER...THE TRANSITION TO
SNOW DOES NOT PAN OUT AS CURRENT THINKING SUGGESTS...WINDS WOULD BE
THE MAIN HAZARD ON FRIDAY...AND THE WINTER WEATHER ADVISORY COULD
THEN BE REPLACED WITH A WIND ADVISORY. THEREFORE...IN SPITE OF THE
UNCERTAINTIES ON WHEN CHANGE OVERS TO SNOW WILL OCCUR AND HOW MUCH
SNOW WILL ACTUALLY FALL...WE FEEL AT THIS POINT...TO ERROR ON THE
SIDE OF CAUTION...AS THERE IS A POTENTIAL FOR SOME VERY HEAVY SNOW
IN ADDITION TO THE STRONG WINDS.

THE WINDS ARE EXPECTED TO GRADUALLY VEER MORE NORTHEASTERLY FRIDAY
NIGHT...AND THIS COULD ALLOW SOME OF THE LAKE EFFECT PRECIPITATION TO
GET INTO NORTHEASTERN ILLINOIS FOR A BRIEF PERIOD FRIDAY EVENING.
HOWEVER...MODEL GUIDANCE CONTINUES TO SUGGEST THAT INVERSION HEIGHTS
WILL CRASH IN A HURRY BY LATE FRIDAY EVENING AS HEIGHTS AND
TEMPERATURES BEGIN TO RISE ALOFT. THEREFORE...ANY SNOW SHOWERS THAT
GET INTO NORTHEASTERN ILLINOIS WOULD LIKELY BE LIGHT AND COME TO AN
END LATE FRIDAY NIGHT/EARLY SAT MORNING.

HIGH TEMPERATURES AREA-WIDE LOOK TO REMAIN IN THE LOWER 40S AT BEST
ON FRIDAY AND SATURDAY

LONG TERM...SUNDAY THROUGH WEDNESDAY...

HIGH TEMPERATURES WILL MODERATE INTO EARLY NEXT WEEK AS THE
WESTERN CONUS UPPER RIDGE BUILDS EASTWARD OVER THE REGION. ANOTHER
COLD FRONT LOOKS TO TAKE AIM ON THE AREA AROUND NEXT
TUESDAY...WHICH WILL RESULT IN OUR NEXT CHANCE OF SHOWERS.
OTHERWISE TEMPERATURES LOOK TO REMAIN NEAR NORMAL DURING THE LATER
HALF OF THE WEEK.

KJB

&&

.AVIATION...

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

* NO ISSUES IN THE NEAR TERM.

* SOUTHWEST WINDS SHIFTING TO THE NORTHWEST WITH FROPA
  TONIGHT...WITH GUSTS INCREASING THROUGH MIDDAY FRIDAY WHILE
  BECOMING MORE NORTHERLY.

* CHANCE OF -SHRA/-SHSN TONIGHT THROUGH EARLY FRIDAY MORNING.

* MVFR CEILINGS LATE TONIGHT INTO FRIDAY MORNING.

RODRIGUEZ/CMS

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

RELATIVELY QUIET CONDITIONS EARLY THIS AFTERNOON WILL CONTINUE THIS
AFTERNOON...WHILE SOUTHWEST WINDS PREVAIL AND MID/HIGH LEVEL CLOUD
COVER CONTINUE TO STREAM OVERHEAD. CONDITIONS WILL BEGIN
DETERIORATING TONIGHT AS SYSTEM/FRONT PUSH THROUGH THE REGION. THE
CURRENT SOUTHWEST WINDS WILL TURN WEST AND NORTHWEST TONIGHT WITH
WIND SPEED/GUSTS QUICKLY INCREASING. LOWERING CEILINGS TO MVFR WILL
ALSO OCCUR WITH THE ARRIVAL OF THIS WIND SHIFT...LIKELY PERSISTING
FOR MUCH OF FRIDAY MORNING. MOISTURE WILL ALSO BE SUFFICIENT FOR
RAIN SHOWERS TO INITIALLY BE POSSIBLE BUT WITH MUCH COLDER AIR
QUICKLY FILTERING IN...SNOW SHOWERS WILL THEN BE POSSIBLE. EXPECT
THESE RAIN/SNOW SHOWERS TO BE ON THE LIGHTER SIDE...WITH NO VIS
RESTRICTION EXPECTED AS WELL AS NO SNOW ACCUMULATION. THE WINDS WILL
CONTINUE TO SHIFT MORE NORTHERLY FRIDAY MORNING AND LIKELY REMAIN IN
THIS NORTH DIRECTION FOR MUCH OF FRIDAY. THIS ORIENTATION WILL
COINCIDE WITH VERY STRONG WINDS...WITH GUSTS ANTICIPATED TO BE
AROUND 40 KT. CONDITIONS SHOULD BE BACK TO VFR FOR THE REMAINDER OF
THE DAY/FORECAST PERIOD...BUT A TREND BACK TOWARDS DETERIORATING
CONDITIONS COULD BE POSSIBLE IF LAKE EFFECT PRECIP AND CLOUD COVER
MOVE TOWARDS THE TERMINALS FRIDAY EVENING.

RODRIGUEZ

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

* HIGH CONFIDENCE OF VFR CONDITIONS IN THE NEAR TERM.

* HIGH CONFIDENCE OF WIND DIRECTION AND SPEED/GUSTS...MEDIUM HIGH
  CONFIDENCE OF EXACT TIMING OF FROPA.

* HIGH CONFIDENCE OF -SHRA/-SHSN...MEDIUM CONFIDENCE OF DURATION.

* HIGH CONFIDENCE OF MVFR CEILINGS...MEDIUM CONFIDENCE OF DURATION.

RODRIGUEZ/CMS

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

* FRIDAY NIGHT...STRONG NORTH WINDS GUSTING TO 30 KT. CHANCE OF
  SHRA OR SHSN.

* SATURDAY...VFR. WX NIL. NORTHEAST WINDS 10-15KT.

* SUNDAY...VFR. WX NIL. SOUTH WINDS.

* MONDAY...CHANCE OF SHRA. GUSTY SOUTHERLY WINDS.

* TUESDAY...CHANCE OF SHRA. WESTERLY WINDS.

* WEDNESDAY...VFR. WX NIL. SOUTHWEST WINDS.

&&

.MARINE...
250 PM CDT

A VERY ACTIVE PERIOD OVER LAKE MICHIGAN BEGINNING LATER TONIGHT. THE
AREA WILL FIND ITSELF IN A FAVORABLE AND ANOMALOUS SYNOPTIC WEATHER
PATTERN FOR STRONG NORTHERLY WINDS...AND THIS WILL BE FURTHER AIDED
BY THE WARM WATERS/EXTREME INSTABILITY TO PRODUCE REGULAR HIGHER END
STORM FORCE GUSTS PERSISTING INTO FRIDAY. A STRONG COLD FRONT WILL
MOVE DOWN THE LAKE RAPIDLY FROM AROUND MIDNIGHT THROUGH 5 AM.
IMMEDIATELY BEHIND THIS A VERY TIGHT PRESSURE GRADIENT IN SYNC WITH
COLD AIR ADVECTION WILL PRODUCE A RAMP UP IN NORTHERLY WIND SPEEDS.
THE HIGHEST WIND SPEEDS OF STORM FORCE TO 50 AND POSSIBLY EVEN 55 KT
ARE EXPECTED LATE TONIGHT THROUGH MID FRIDAY AFTERNOON FOR THE
CENTRAL AND SOUTHERN PART OF THE LAKE...AND AFTER DAYBREAK THROUGH
THE DAY ON FRIDAY FOR THE NEARSHORE AREAS OF ILLINOIS AND INDIANA.
THE WAVE MAXIMUM OF OVER 20 FOOTERS IS EXPECTED TO DEVELOP OVER THE
CENTRAL PART OF THE LAKE EARLY FRIDAY MORNING AND EVOLVE SOUTHWARD
REACHING THE ILLINOIS AND INDIANA NEARSHORE FRIDAY AFTERNOON AND
EARLY EVENING. WAVES WILL BE VERY SLOW TO SUBSIDE THROUGH LATE
FRIDAY NIGHT AND EARLY SATURDAY. HIGH PRESSURE WILL MOVE QUICKLY
OVER THE LAKE SATURDAY NIGHT BEFORE SOUTHERLY FLOW RETURNS TO THE
LAKE.

MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WIND ADVISORY...ILZ014...7 AM FRIDAY TO 10 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022...7 AM
     FRIDAY TO 7 PM FRIDAY.

     WIND ADVISORY...ILZ023-ILZ033...10 AM FRIDAY TO 7 PM FRIDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011...10 AM
     FRIDAY TO 10 PM FRIDAY.

     WIND ADVISORY...INZ019...10 AM FRIDAY TO 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 PM FRIDAY TO
     4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
     LMZ878...3 AM FRIDAY TO 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563...1 AM FRIDAY TO 10
     PM FRIDAY.

     GALE WARNING...LMZ740...4 AM FRIDAY TO 4 AM SATURDAY.

     STORM WARNING...LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...4 AM FRIDAY
     TO 7 PM FRIDAY.

&&

$$

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000
FXUS63 KLOT 302206
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
506 PM CDT THU OCT 30 2014

.DISCUSSION...

SHORT TERM...TONIGHT THROUGH SATURDAY...
THE MAIN FORECAST FOCUS THIS AFTERNOON CONTINUES TO CENTER AROUND
THE STORM SYSTEM EXPECTED IMPACT THE REGION LATE TONIGHT THROUGH
FRIDAY NIGHT. STRONG WINDS...AND THE POTENTIAL FOR SOME PERIODS OF
HEAVY LAKE EFFECT SNOW ARE THE PRIMARY CONCERNS.

WE ARE ISSUING A WIND ADVISORY FOR MOST OF THE EASTERN HALF OF THE
AREA...WITH THE EXCEPTION OF LAKE...PORTER...JASPER AND NEWTON
COUNTIES IN INDIANA...WHERE A WINTER WEATHER ADVISORY IS BEING
ISSUED. SEE BELOW FOR MORE DETAILS.

WATER VAPOR IMAGERY EARLY THIS AFTERNOON SHOWS A RATHER VIGOROUS
UPPER LEVEL IMPULSE NOW MOVING JUST EAST OF LAKE WINNIPEG AND OVER
FAR SOUTHWESTERN ONTARIO. THIS WAVE IS EXPECTED TO CONTINUE DIGGING
SOUTH-SOUTHEASTWARD TONIGHT ALONG THE EASTERN PERIPHERY OF AN UPPER
RIDGE...CURRENT CENTERED ACROSS THE INTER MOUNTAIN WEST. AS THIS
OCCURS...AN AREA OF SURFACE LOW PRESSURE WILL SHIFT SOUTHWARD ACROSS
LOWER MICHIGAN INTO FRIDAY MORNING. FARTHER NORTHWEST...A RATHER
STOUT 1036 MB HIGH IS ALSO EXPECTED TO RAPIDLY BUILD SOUTHEASTWARD
ACROSS THE DAKOTAS AND UPPER MIDWEST INTO FRIDAY. THIS STILL LOOKS
TO SET THE STAGE FOR STRONG NORTHERN WINDS ACROSS THE AREA DURING
THE DAY FRIDAY AS STRONG PRESSURE RISES AND STRONG COLD AIR
ADVECTION LEAD TO A QUICK RAMP UP OF NORTHERLY WINDS IN THE WAKE OF
A COLD FRONTAL PASSAGE LATE TONIGHT. MODEL SOUNDINGS ALL SUGGEST
MEAN MIXING LAYER WIND SPEEDS COULD TOP 40 KT ACROSS MAINLY THE
EASTERN HALF OF THE AREA INLAND FROM THE LAKE...MEANING WIND GUSTS
COULD EASILY REACH THIS MAGNITUDE IN MOST AREAS. HOWEVER...AREAS
DIRECTLY ADJACENT TO LAKE MICHIGAN IN NORTHEASTERN ILLINOIS AND
NORTHWESTERN INDIANA COULD EXPERIENCE EVEN STRONGER GUSTS UP AROUND
50 KT WITH THE STRONG NORTHERLY ONSHORE COMPONENT TO THE WINDS.
WINDS LOOK TO REMAIN INTO THE EVENING ON HALLOWEEN...THOUGH WIND
SPEEDS SHOULD GRADUALLY WEAKEN THROUGH THE NIGHT.

THE LAKE SHORE FLOOD ADVISORY WILL CONTINUE FOR AREAS NEAR THE LAKE
AS LARGE BATTERING WAVES IN EXCESS OF 20 FT APPEAR LIKELY...AND AS
THE PREVIOUS DISCUSSION MENTIONED...LAKE LEVELS ARE ABOUT 2 FT
HIGHER THAN PAST YEARS...WHICH COULD MAKE THE IMPACTS OF THESE WAVES
HIGHER THEN SIMILAR WAVE EVENTS IN THE PAST COUPLE OF YEARS.

DUE TO THE LIKELIHOOD OF THESE STRONG WINDS...WE HAVE ISSUED A WIND
ADVISORY FOR MUCH OF THE EASTERN HALF OF MY CWA. THIS
INCLUDES AREAS BASICALLY ALONG AND EAST OF A LINE FROM HARVARD
SOUTHWARD THROUGH KANKAKEE AND IROQUOIS COUNTIES. THE ONLY EXCEPTION
TO THIS WIND ADVISORY IS FOR LAKE COUNTY INDIANA...AS WELL AS
PORTER...JASPER AND NEWTON COUNTIES...WHERE A WINTER WEATHER
ADVISORY IS BEING ISSUED IN PLACE OF A WIND ADVISORY FOR THE
COMBINATION OF THESE STRONG WINDS AND ALSO THE INCREASING POTENTIAL
FOR SOME ACCUMULATING LAKE EFFECT SNOW ON FRIDAY INTO FRIDAY
EVENING.

PRECIPITATION WITH THE APPROACHING COLD FRONT AND UPPER LEVEL IMPULSE
WILL LIKELY BEGIN TO ENTER FAR NORTHERN ILLINOIS AFTER 10 PM THIS
EVENING...AND BE IN THE FORM OF RAIN SHOWERS. THIS INITIAL ROUND OF
SHOWERS SHOULD MOVE SOUTHWARD ACROSS THE AREA THROUGH THE NIGHT...IN
CLOSE PROXIMITY THE INCREASING FRONTOGENESIS IN THE VICINITY OF THE
COLD FRONTAL BOUNDARY. THIS SHOULD BE A FAIRLY PROGRESSIVE AREA OF
SHOWERS...WITH MOST AREAS ACROSS NORTH CENTRAL ILLINOIS DRYING OUT BY
EARLY FRIDAY MORNING.

THE SECOND STAGE OF PRECIPITATION WILL BE MORE OF A TRUE LAKE EFFECT
SETUP. A COLD AIRMASS FEATURING -7 DEGREE C TEMPERATURES AT 850 MB
WILL MOVE OVER THE LAKE...WHICH IS CURRENTLY REPORTING A 53F (11.7C)
DEGREE WATER TEMPERATURE AT THE SOUTH BUOY. THEREFORE...DELTA T`S
SHOULD END UP VERY FAVORABLE AROUND 19 DEGREES C. IN ADDITION...DEEP
LAKE INDUCED INSTABILITY IS STILL EXPECTED...WITH EQUILIBRIUM LEVELS
LIKELY TO REACH OR EVEN EXCEED 16,000 FT AGL. THEREFORE...THE THREAT
FOR THUNDER AND LIGHTNING HAS NOT CHANGED...WITH CONVECTIVE PROCESSES
LIKELY TO BE MORE THAN DEEP ENOUGH THROUGH THE -10 TO -20 LAYER TO
RESULT IN GOOD CHARGE SEPARATION.

IT LOOKS AS THOUGH THIS LAKE EFFECT BAND COULD BEGIN TO SET UP
ACROSS NORTHWESTERN INDIANA AND PERHAPS PORTIONS OF SOUTHEASTERN COOK
COUNTY BY LATE FRIDAY MORNING. HI RES GUIDANCE SUGGESTS UNCERTAINTY
ON THE EXACT AREAS THAT WILL GET THIS LAKE EFFECT BANDING. SOME HAVE
HINTED IN A FARTHER WEST BAND...WHICH WOULD IMPACT MORE OF THE
CHICAGO AREA. HOWEVER...I THINK AT THIS POINT AREAS IN NORTHWEST
INDIANA WILL BE MORE FAVORED...WITH THE LIKELIHOOD OF A NEARLY DUE
NORTH BOUNDARY LAYER FLOW SETTING UP OVER LAKE MICHIGAN. THIS WOULD
TEND TO FAVOR BETTER BOUNDARY LAYER CONVERGENCE ALONG THE SOUTHERN
TIP OF LAKE MICHIGAN FRIDAY AFTERNOON...WHICH SUGGESTS THAT PORTER
AND LAKE INDIANA WILL BE MORE IN LINE WITH THE POTENTIAL HEAVIER
PRECIPITATION. DUE TO THE STRONG WINDS...IT IS ALSO LIKELY THAT THIS
LAKE EFFECT PRECIP COULD BE DRIVEN WELL INLAND ACROSS NORTHWESTERN
INDIANA...POSSIBLY IMPACTING MUCH OF JASPER AND PORTER COUNTIES AS
WELL.

UNCERTAINTY IN PRECIPITATION TYPE IS STILL SOMEWHAT HIGH...AS
SOME WARMER AIR MOVING OFF THE LAKE SHOULD MAKE BOUNDARY LAYER
TEMPERATURES MARGINAL FOR SNOW TO REACH THE SURFACE. HOWEVER...WITH
THE AFOREMENTIONED CONVECTIVE INSTABILITY AND THE GOOD POTENTIAL FOR
SOME HEAVIER PRECIP RATES...IT IS VERY MUCH IN THE REALM OF
POSSIBILITIES THAT ENHANCED DYNAMIC COOLING COULD RESULT IN A COLD
ENOUGH BOUNDARY LAYER SUPPORTIVE OF HEAVY SNOW. IT APPEARS THAT
AREAS INLAND FROM THE IMMEDIATE LAKE SHORE WOULD HAVE THE BEST
POTENTIAL FOR SNOW...THOUGH EVEN AREAS ALONG THE LAKE COULD CHANGE
OVER/MIX WITH SNOW. OVERALL...WITH THE POTENTIAL FOR SOME HEAVIER
BANDS OF SNOW WITH SOME ACCUMULATIONS POSSIBLE (POSSIBLY A FEW
INCHES IN SOME AREAS) ALONG WITH THE VERY STRONG NORTHERLY
WINDS...WE HAVE CHOSEN TO ISSUE THE WINTER WEATHER ADVISORY FOR THE
4 NORTHWESTERN INDIANA COUNTIES. IF...HOWEVER...THE TRANSITION TO
SNOW DOES NOT PAN OUT AS CURRENT THINKING SUGGESTS...WINDS WOULD BE
THE MAIN HAZARD ON FRIDAY...AND THE WINTER WEATHER ADVISORY COULD
THEN BE REPLACED WITH A WIND ADVISORY. THEREFORE...IN SPITE OF THE
UNCERTAINTIES ON WHEN CHANGE OVERS TO SNOW WILL OCCUR AND HOW MUCH
SNOW WILL ACTUALLY FALL...WE FEEL AT THIS POINT...TO ERROR ON THE
SIDE OF CAUTION...AS THERE IS A POTENTIAL FOR SOME VERY HEAVY SNOW
IN ADDITION TO THE STRONG WINDS.

THE WINDS ARE EXPECTED TO GRADUALLY VEER MORE NORTHEASTERLY FRIDAY
NIGHT...AND THIS COULD ALLOW SOME OF THE LAKE EFFECT PRECIPITATION TO
GET INTO NORTHEASTERN ILLINOIS FOR A BRIEF PERIOD FRIDAY EVENING.
HOWEVER...MODEL GUIDANCE CONTINUES TO SUGGEST THAT INVERSION HEIGHTS
WILL CRASH IN A HURRY BY LATE FRIDAY EVENING AS HEIGHTS AND
TEMPERATURES BEGIN TO RISE ALOFT. THEREFORE...ANY SNOW SHOWERS THAT
GET INTO NORTHEASTERN ILLINOIS WOULD LIKELY BE LIGHT AND COME TO AN
END LATE FRIDAY NIGHT/EARLY SAT MORNING.

HIGH TEMPERATURES AREA-WIDE LOOK TO REMAIN IN THE LOWER 40S AT BEST
ON FRIDAY AND SATURDAY

LONG TERM...SUNDAY THROUGH WEDNESDAY...

HIGH TEMPERATURES WILL MODERATE INTO EARLY NEXT WEEK AS THE
WESTERN CONUS UPPER RIDGE BUILDS EASTWARD OVER THE REGION. ANOTHER
COLD FRONT LOOKS TO TAKE AIM ON THE AREA AROUND NEXT
TUESDAY...WHICH WILL RESULT IN OUR NEXT CHANCE OF SHOWERS.
OTHERWISE TEMPERATURES LOOK TO REMAIN NEAR NORMAL DURING THE LATER
HALF OF THE WEEK.

KJB

&&

.AVIATION...

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

* NO ISSUES IN THE NEAR TERM.

* SOUTHWEST WINDS SHIFTING TO THE NORTHWEST WITH FROPA
  TONIGHT...WITH GUSTS INCREASING THROUGH MIDDAY FRIDAY WHILE
  BECOMING MORE NORTHERLY.

* CHANCE OF -SHRA/-SHSN TONIGHT THROUGH EARLY FRIDAY MORNING.

* MVFR CEILINGS LATE TONIGHT INTO FRIDAY MORNING.

RODRIGUEZ/CMS

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

RELATIVELY QUIET CONDITIONS EARLY THIS AFTERNOON WILL CONTINUE THIS
AFTERNOON...WHILE SOUTHWEST WINDS PREVAIL AND MID/HIGH LEVEL CLOUD
COVER CONTINUE TO STREAM OVERHEAD. CONDITIONS WILL BEGIN
DETERIORATING TONIGHT AS SYSTEM/FRONT PUSH THROUGH THE REGION. THE
CURRENT SOUTHWEST WINDS WILL TURN WEST AND NORTHWEST TONIGHT WITH
WIND SPEED/GUSTS QUICKLY INCREASING. LOWERING CEILINGS TO MVFR WILL
ALSO OCCUR WITH THE ARRIVAL OF THIS WIND SHIFT...LIKELY PERSISTING
FOR MUCH OF FRIDAY MORNING. MOISTURE WILL ALSO BE SUFFICIENT FOR
RAIN SHOWERS TO INITIALLY BE POSSIBLE BUT WITH MUCH COLDER AIR
QUICKLY FILTERING IN...SNOW SHOWERS WILL THEN BE POSSIBLE. EXPECT
THESE RAIN/SNOW SHOWERS TO BE ON THE LIGHTER SIDE...WITH NO VIS
RESTRICTION EXPECTED AS WELL AS NO SNOW ACCUMULATION. THE WINDS WILL
CONTINUE TO SHIFT MORE NORTHERLY FRIDAY MORNING AND LIKELY REMAIN IN
THIS NORTH DIRECTION FOR MUCH OF FRIDAY. THIS ORIENTATION WILL
COINCIDE WITH VERY STRONG WINDS...WITH GUSTS ANTICIPATED TO BE
AROUND 40 KT. CONDITIONS SHOULD BE BACK TO VFR FOR THE REMAINDER OF
THE DAY/FORECAST PERIOD...BUT A TREND BACK TOWARDS DETERIORATING
CONDITIONS COULD BE POSSIBLE IF LAKE EFFECT PRECIP AND CLOUD COVER
MOVE TOWARDS THE TERMINALS FRIDAY EVENING.

RODRIGUEZ

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

* HIGH CONFIDENCE OF VFR CONDITIONS IN THE NEAR TERM.

* HIGH CONFIDENCE OF WIND DIRECTION AND SPEED/GUSTS...MEDIUM HIGH
  CONFIDENCE OF EXACT TIMING OF FROPA.

* HIGH CONFIDENCE OF -SHRA/-SHSN...MEDIUM CONFIDENCE OF DURATION.

* HIGH CONFIDENCE OF MVFR CEILINGS...MEDIUM CONFIDENCE OF DURATION.

RODRIGUEZ/CMS

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

* FRIDAY NIGHT...STRONG NORTH WINDS GUSTING TO 30 KT. CHANCE OF
  SHRA OR SHSN.

* SATURDAY...VFR. WX NIL. NORTHEAST WINDS 10-15KT.

* SUNDAY...VFR. WX NIL. SOUTH WINDS.

* MONDAY...CHANCE OF SHRA. GUSTY SOUTHERLY WINDS.

* TUESDAY...CHANCE OF SHRA. WESTERLY WINDS.

* WEDNESDAY...VFR. WX NIL. SOUTHWEST WINDS.

&&

.MARINE...
250 PM CDT

A VERY ACTIVE PERIOD OVER LAKE MICHIGAN BEGINNING LATER TONIGHT. THE
AREA WILL FIND ITSELF IN A FAVORABLE AND ANOMALOUS SYNOPTIC WEATHER
PATTERN FOR STRONG NORTHERLY WINDS...AND THIS WILL BE FURTHER AIDED
BY THE WARM WATERS/EXTREME INSTABILITY TO PRODUCE REGULAR HIGHER END
STORM FORCE GUSTS PERSISTING INTO FRIDAY. A STRONG COLD FRONT WILL
MOVE DOWN THE LAKE RAPIDLY FROM AROUND MIDNIGHT THROUGH 5 AM.
IMMEDIATELY BEHIND THIS A VERY TIGHT PRESSURE GRADIENT IN SYNC WITH
COLD AIR ADVECTION WILL PRODUCE A RAMP UP IN NORTHERLY WIND SPEEDS.
THE HIGHEST WIND SPEEDS OF STORM FORCE TO 50 AND POSSIBLY EVEN 55 KT
ARE EXPECTED LATE TONIGHT THROUGH MID FRIDAY AFTERNOON FOR THE
CENTRAL AND SOUTHERN PART OF THE LAKE...AND AFTER DAYBREAK THROUGH
THE DAY ON FRIDAY FOR THE NEARSHORE AREAS OF ILLINOIS AND INDIANA.
THE WAVE MAXIMUM OF OVER 20 FOOTERS IS EXPECTED TO DEVELOP OVER THE
CENTRAL PART OF THE LAKE EARLY FRIDAY MORNING AND EVOLVE SOUTHWARD
REACHING THE ILLINOIS AND INDIANA NEARSHORE FRIDAY AFTERNOON AND
EARLY EVENING. WAVES WILL BE VERY SLOW TO SUBSIDE THROUGH LATE
FRIDAY NIGHT AND EARLY SATURDAY. HIGH PRESSURE WILL MOVE QUICKLY
OVER THE LAKE SATURDAY NIGHT BEFORE SOUTHERLY FLOW RETURNS TO THE
LAKE.

MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WIND ADVISORY...ILZ014...7 AM FRIDAY TO 10 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022...7 AM
     FRIDAY TO 7 PM FRIDAY.

     WIND ADVISORY...ILZ023-ILZ033...10 AM FRIDAY TO 7 PM FRIDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011...10 AM
     FRIDAY TO 10 PM FRIDAY.

     WIND ADVISORY...INZ019...10 AM FRIDAY TO 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 PM FRIDAY TO
     4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
     LMZ878...3 AM FRIDAY TO 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563...1 AM FRIDAY TO 10
     PM FRIDAY.

     GALE WARNING...LMZ740...4 AM FRIDAY TO 4 AM SATURDAY.

     STORM WARNING...LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...4 AM FRIDAY
     TO 7 PM FRIDAY.

&&

$$

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000
FXUS63 KLOT 302032
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
332 PM CDT THU OCT 30 2014


.DISCUSSION...

SHORT TERM...TONIGHT THROUGH SATURDAY...
THE MAIN FORECAST FOCUS THIS AFTERNOON CONTINUES TO CENTER AROUND
THE STORM SYSTEM EXPECTED IMPACT THE REGION LATE TONIGHT THROUGH
FRIDAY NIGHT. STRONG WINDS...AND THE POTENTIAL FOR SOME PERIODS OF
HEAVY LAKE EFFECT SNOW ARE THE PRIMARY CONCERNS.

WE ARE ISSUING A WIND ADVISORY FOR MOST OF THE EASTERN HALF OF THE
AREA...WITH THE EXCEPTION OF LAKE...PORTER...JASPER AND NEWTON
COUNTIES IN INDIANA...WHERE A WINTER WEATHER ADVISORY IS BEING
ISSUED. SEE BELOW FOR MORE DETAILS.

WATER VAPOR IMAGERY EARLY THIS AFTERNOON SHOWS A RATHER VIGOROUS
UPPER LEVEL IMPULSE NOW MOVING JUST EAST OF LAKE WINNIPEG AND OVER
FAR SOUTHWESTERN ONTARIO. THIS WAVE IS EXPECTED TO CONTINUE DIGGING
SOUTH-SOUTHEASTWARD TONIGHT ALONG THE EASTERN PERIPHERY OF AN UPPER
RIDGE...CURRENT CENTERED ACROSS THE INTER MOUNTAIN WEST. AS THIS
OCCURS...AN AREA OF SURFACE LOW PRESSURE WILL SHIFT SOUTHWARD ACROSS
LOWER MICHIGAN INTO FRIDAY MORNING. FARTHER NORTHWEST...A RATHER
STOUT 1036 MB HIGH IS ALSO EXPECTED TO RAPIDLY BUILD SOUTHEASTWARD
ACROSS THE DAKOTAS AND UPPER MIDWEST INTO FRIDAY. THIS STILL LOOKS
TO SET THE STAGE FOR STRONG NORTHERN WINDS ACROSS THE AREA DURING
THE DAY FRIDAY AS STRONG PRESSURE RISES AND STRONG COLD AIR
ADVECTION LEAD TO A QUICK RAMP UP OF NORTHERLY WINDS IN THE WAKE OF
A COLD FRONTAL PASSAGE LATE TONIGHT. MODEL SOUNDINGS ALL SUGGEST
MEAN MIXING LAYER WIND SPEEDS COULD TOP 40 KT ACROSS MAINLY THE
EASTERN HALF OF THE AREA INLAND FROM THE LAKE...MEANING WIND GUSTS
COULD EASILY REACH THIS MAGNITUDE IN MOST AREAS. HOWEVER...AREAS
DIRECTLY ADJACENT TO LAKE MICHIGAN IN NORTHEASTERN ILLINOIS AND
NORTHWESTERN INDIANA COULD EXPERIENCE EVEN STRONGER GUSTS UP AROUND
50 KT WITH THE STRONG NORTHERLY ONSHORE COMPONENT TO THE WINDS.
WINDS LOOK TO REMAIN INTO THE EVENING ON HALLOWEEN...THOUGH WIND
SPEEDS SHOULD GRADUALLY WEAKEN THROUGH THE NIGHT.

THE LAKE SHORE FLOOD ADVISORY WILL CONTINUE FOR AREAS NEAR THE LAKE
AS LARGE BATTERING WAVES IN EXCESS OF 20 FT APPEAR LIKELY...AND AS
THE PREVIOUS DISCUSSION MENTIONED...LAKE LEVELS ARE ABOUT 2 FT
HIGHER THAN PAST YEARS...WHICH COULD MAKE THE IMPACTS OF THESE WAVES
HIGHER THEN SIMILAR WAVE EVENTS IN THE PAST COUPLE OF YEARS.

DUE TO THE LIKELIHOOD OF THESE STRONG WINDS...WE HAVE ISSUED A WIND
ADVISORY FOR MUCH OF THE EASTERN HALF OF MY CWA. THIS
INCLUDES AREAS BASICALLY ALONG AND EAST OF A LINE FROM HARVARD
SOUTHWARD THROUGH KANKAKEE AND IROQUOIS COUNTIES. THE ONLY EXCEPTION
TO THIS WIND ADVISORY IS FOR LAKE COUNTY INDIANA...AS WELL AS
PORTER...JASPER AND NEWTON COUNTIES...WHERE A WINTER WEATHER
ADVISORY IS BEING ISSUED IN PLACE OF A WIND ADVISORY FOR THE
COMBINATION OF THESE STRONG WINDS AND ALSO THE INCREASING POTENTIAL
FOR SOME ACCUMULATING LAKE EFFECT SNOW ON FRIDAY INTO FRIDAY
EVENING.

PRECIPITATION WITH THE APPROACHING COLD FRONT AND UPPER LEVEL IMPULSE
WILL LIKELY BEGIN TO ENTER FAR NORTHERN ILLINOIS AFTER 10 PM THIS
EVENING...AND BE IN THE FORM OF RAIN SHOWERS. THIS INITIAL ROUND OF
SHOWERS SHOULD MOVE SOUTHWARD ACROSS THE AREA THROUGH THE NIGHT...IN
CLOSE PROXIMITY THE INCREASING FRONTOGENESIS IN THE VICINITY OF THE
COLD FRONTAL BOUNDARY. THIS SHOULD BE A FAIRLY PROGRESSIVE AREA OF
SHOWERS...WITH MOST AREAS ACROSS NORTH CENTRAL ILLINOIS DRYING OUT BY
EARLY FRIDAY MORNING.

THE SECOND STAGE OF PRECIPITATION WILL BE MORE OF A TRUE LAKE EFFECT
SETUP. A COLD AIRMASS FEATURING -7 DEGREE C TEMPERATURES AT 850 MB
WILL MOVE OVER THE LAKE...WHICH IS CURRENTLY REPORTING A 53F (11.7C)
DEGREE WATER TEMPERATURE AT THE SOUTH BUOY. THEREFORE...DELTA T`S
SHOULD END UP VERY FAVORABLE AROUND 19 DEGREES C. IN ADDITION...DEEP
LAKE INDUCED INSTABILITY IS STILL EXPECTED...WITH EQUILIBRIUM LEVELS
LIKELY TO REACH OR EVEN EXCEED 16,000 FT AGL. THEREFORE...THE THREAT
FOR THUNDER AND LIGHTNING HAS NOT CHANGED...WITH CONVECTIVE PROCESSES
LIKELY TO BE MORE THAN DEEP ENOUGH THROUGH THE -10 TO -20 LAYER TO
RESULT IN GOOD CHARGE SEPARATION.

IT LOOKS AS THOUGH THIS LAKE EFFECT BAND COULD BEGIN TO SET UP
ACROSS NORTHWESTERN INDIANA AND PERHAPS PORTIONS OF SOUTHEASTERN COOK
COUNTY BY LATE FRIDAY MORNING. HI RES GUIDANCE SUGGESTS UNCERTAINTY
ON THE EXACT AREAS THAT WILL GET THIS LAKE EFFECT BANDING. SOME HAVE
HINTED IN A FARTHER WEST BAND...WHICH WOULD IMPACT MORE OF THE
CHICAGO AREA. HOWEVER...I THINK AT THIS POINT AREAS IN NORTHWEST
INDIANA WILL BE MORE FAVORED...WITH THE LIKELIHOOD OF A NEARLY DUE
NORTH BOUNDARY LAYER FLOW SETTING UP OVER LAKE MICHIGAN. THIS WOULD
TEND TO FAVOR BETTER BOUNDARY LAYER CONVERGENCE ALONG THE SOUTHERN
TIP OF LAKE MICHIGAN FRIDAY AFTERNOON...WHICH SUGGESTS THAT PORTER
AND LAKE INDIANA WILL BE MORE IN LINE WITH THE POTENTIAL HEAVIER
PRECIPITATION. DUE TO THE STRONG WINDS...IT IS ALSO LIKELY THAT THIS
LAKE EFFECT PRECIP COULD BE DRIVEN WELL INLAND ACROSS NORTHWESTERN
INDIANA...POSSIBLY IMPACTING MUCH OF JASPER AND PORTER COUNTIES AS
WELL.

UNCERTAINTY IN PRECIPITATION TYPE IS STILL SOMEWHAT HIGH...AS
SOME WARMER AIR MOVING OFF THE LAKE SHOULD MAKE BOUNDARY LAYER
TEMPERATURES MARGINAL FOR SNOW TO REACH THE SURFACE. HOWEVER...WITH
THE AFOREMENTIONED CONVECTIVE INSTABILITY AND THE GOOD POTENTIAL FOR
SOME HEAVIER PRECIP RATES...IT IS VERY MUCH IN THE REALM OF
POSSIBILITIES THAT ENHANCED DYNAMIC COOLING COULD RESULT IN A COLD
ENOUGH BOUNDARY LAYER SUPPORTIVE OF HEAVY SNOW. IT APPEARS THAT
AREAS INLAND FROM THE IMMEDIATE LAKE SHORE WOULD HAVE THE BEST
POTENTIAL FOR SNOW...THOUGH EVEN AREAS ALONG THE LAKE COULD CHANGE
OVER/MIX WITH SNOW. OVERALL...WITH THE POTENTIAL FOR SOME HEAVIER
BANDS OF SNOW WITH SOME ACCUMULATIONS POSSIBLE (POSSIBLY A FEW
INCHES IN SOME AREAS) ALONG WITH THE VERY STRONG NORTHERLY
WINDS...WE HAVE CHOSEN TO ISSUE THE WINTER WEATHER ADVISORY FOR THE
4 NORTHWESTERN INDIANA COUNTIES. IF...HOWEVER...THE TRANSITION TO
SNOW DOES NOT PAN OUT AS CURRENT THINKING SUGGESTS...WINDS WOULD BE
THE MAIN HAZARD ON FRIDAY...AND THE WINTER WEATHER ADVISORY COULD
THEN BE REPLACED WITH A WIND ADVISORY. THEREFORE...IN SPITE OF THE
UNCERTAINTIES ON WHEN CHANGE OVERS TO SNOW WILL OCCUR AND HOW MUCH
SNOW WILL ACTUALLY FALL...WE FEEL AT THIS POINT...TO ERROR ON THE
SIDE OF CAUTION...AS THERE IS A POTENTIAL FOR SOME VERY HEAVY SNOW
IN ADDITION TO THE STRONG WINDS.

THE WINDS ARE EXPECTED TO GRADUALLY VEER MORE NORTHEASTERLY FRIDAY
NIGHT...AND THIS COULD ALLOW SOME OF THE LAKE EFFECT PRECIPITATION TO
GET INTO NORTHEASTERN ILLINOIS FOR A BRIEF PERIOD FRIDAY EVENING.
HOWEVER...MODEL GUIDANCE CONTINUES TO SUGGEST THAT INVERSION HEIGHTS
WILL CRASH IN A HURRY BY LATE FRIDAY EVENING AS HEIGHTS AND
TEMPERATURES BEGIN TO RISE ALOFT. THEREFORE...ANY SNOW SHOWERS THAT
GET INTO NORTHEASTERN ILLINOIS WOULD LIKELY BE LIGHT AND COME TO AN
END LATE FRIDAY NIGHT/EARLY SAT MORNING.

HIGH TEMPERATURES AREA-WIDE LOOK TO REMAIN IN THE LOWER 40S AT BEST
ON FRIDAY AND SATURDAY

LONG TERM...SUNDAY THROUGH WEDNESDAY...

HIGH TEMPERATURES WILL MODERATE INTO EARLY NEXT WEEK AS THE
WESTERN CONUS UPPER RIDGE BUILDS EASTWARD OVER THE REGION. ANOTHER
COLD FRONT LOOKS TO TAKE AIM ON THE AREA AROUND NEXT
TUESDAY...WHICH WILL RESULT IN OUR NEXT CHANCE OF SHOWERS.
OTHERWISE TEMPERATURES LOOK TO REMAIN NEAR NORMAL DURING THE LATER
HALF OF THE WEEK.

KJB

&&

.AVIATION...

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

* NO ISSUES IN THE NEAR TERM.

* SOUTHWEST WINDS SHIFTING TO THE NORTHWEST WITH FROPA
  TONIGHT...WITH GUSTS INCREASING THROUGH MIDDAY FRIDAY WHILE
  BECOMING MORE NORTHERLY.

* CHANCE OF -SHRA/-SHSN TONIGHT THROUGH EARLY FRIDAY MORNING.

* MVFR CEILINGS LATE TONIGHT INTO FRIDAY MORNING.

RODRIGUEZ

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

RELATIVELY QUIET CONDITIONS EARLY THIS AFTERNOON WILL CONTINUE THIS
AFTERNOON...WHILE SOUTHWEST WINDS PREVAIL AND MID/HIGH LEVEL CLOUD
COVER CONTINUE TO STREAM OVERHEAD. CONDITIONS WILL BEGIN
DETERIORATING TONIGHT AS SYSTEM/FRONT PUSH THROUGH THE REGION. THE
CURRENT SOUTHWEST WINDS WILL TURN WEST AND NORTHWEST TONIGHT WITH
WIND SPEED/GUSTS QUICKLY INCREASING. LOWERING CEILINGS TO MVFR WILL
ALSO OCCUR WITH THE ARRIVAL OF THIS WIND SHIFT...LIKELY PERSISTING
FOR MUCH OF FRIDAY MORNING. MOISTURE WILL ALSO BE SUFFICIENT FOR
RAIN SHOWERS TO INITIALLY BE POSSIBLE BUT WITH MUCH COLDER AIR
QUICKLY FILTERING IN...SNOW SHOWERS WILL THEN BE POSSIBLE. EXPECT
THESE RAIN/SNOW SHOWERS TO BE ON THE LIGHTER SIDE...WITH NO VIS
RESTRICTION EXPECTED AS WELL AS NO SNOW ACCUMULATION. THE WINDS WILL
CONTINUE TO SHIFT MORE NORTHERLY FRIDAY MORNING AND LIKELY REMAIN IN
THIS NORTH DIRECTION FOR MUCH OF FRIDAY. THIS ORIENTATION WILL
COINCIDE WITH VERY STRONG WINDS...WITH GUSTS ANTICIPATED TO BE
AROUND 40 KT. CONDITIONS SHOULD BE BACK TO VFR FOR THE REMAINDER OF
THE DAY/FORECAST PERIOD...BUT A TREND BACK TOWARDS DETERIORATING
CONDITIONS COULD BE POSSIBLE IF LAKE EFFECT PRECIP AND CLOUD COVER
MOVE TOWARDS THE TERMINALS FRIDAY EVENING.

RODRIGUEZ

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

* HIGH CONFIDENCE OF VFR CONDITIONS IN THE NEAR TERM.

* HIGH CONFIDENCE OF WIND DIRECTION AND SPEED/GUSTS...MEDIUM HIGH
  CONFIDENCE OF EXACT TIMING OF FROPA.

* HIGH CONFIDENCE OF -SHRA/-SHSN...MEDIUM CONFIDENCE OF DURATION.

* HIGH CONFIDENCE OF MVFR CEILINGS...MEDIUM CONFIDENCE OF DURATION.

RODRIGUEZ

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

* FRIDAY NIGHT...STRONG NORTH WINDS GUSTING TO 30 KT. CHANCE OF
  SHRA OR SHSN.

* SATURDAY...VFR. WX NIL. NORTHEAST WINDS 10-15KT.

* SUNDAY...VFR. WX NIL. SOUTH WINDS.

* MONDAY...CHANCE OF SHRA. GUSTY SOUTHERLY WINDS.

* TUESDAY...CHANCE OF SHRA. WESTERLY WINDS.

* WEDNESDAY...VFR. WX NIL. SOUTHWEST WINDS.

&&

.MARINE...
250 PM CDT

A VERY ACTIVE PERIOD OVER LAKE MICHIGAN BEGINNING LATER TONIGHT. THE
AREA WILL FIND ITSELF IN A FAVORABLE AND ANOMALOUS SYNOPTIC WEATHER
PATTERN FOR STRONG NORTHERLY WINDS...AND THIS WILL BE FURTHER AIDED
BY THE WARM WATERS/EXTREME INSTABILITY TO PRODUCE REGULAR HIGHER END
STORM FORCE GUSTS PERSISTING INTO FRIDAY. A STRONG COLD FRONT WILL
MOVE DOWN THE LAKE RAPIDLY FROM AROUND MIDNIGHT THROUGH 5 AM.
IMMEDIATELY BEHIND THIS A VERY TIGHT PRESSURE GRADIENT IN SYNC WITH
COLD AIR ADVECTION WILL PRODUCE A RAMP UP IN NORTHERLY WIND SPEEDS.
THE HIGHEST WIND SPEEDS OF STORM FORCE TO 50 AND POSSIBLY EVEN 55 KT
ARE EXPECTED LATE TONIGHT THROUGH MID FRIDAY AFTERNOON FOR THE
CENTRAL AND SOUTHERN PART OF THE LAKE...AND AFTER DAYBREAK THROUGH
THE DAY ON FRIDAY FOR THE NEARSHORE AREAS OF ILLINOIS AND INDIANA.
THE WAVE MAXIMUM OF OVER 20 FOOTERS IS EXPECTED TO DEVELOP OVER THE
CENTRAL PART OF THE LAKE EARLY FRIDAY MORNING AND EVOLVE SOUTHWARD
REACHING THE ILLINOIS AND INDIANA NEARSHORE FRIDAY AFTERNOON AND
EARLY EVENING. WAVES WILL BE VERY SLOW TO SUBSIDE THROUGH LATE
FRIDAY NIGHT AND EARLY SATURDAY. HIGH PRESSURE WILL MOVE QUICKLY
OVER THE LAKE SATURDAY NIGHT BEFORE SOUTHERLY FLOW RETURNS TO THE
LAKE.

MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WIND ADVISORY...ILZ014...7 AM FRIDAY TO 10 PM FRIDAY.

     LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WIND ADVISORY...ILZ005-ILZ006-ILZ012-ILZ013-ILZ020-ILZ022...7 AM
     FRIDAY TO 7 PM FRIDAY.

     WIND ADVISORY...ILZ023-ILZ033...10 AM FRIDAY TO 7 PM FRIDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

     WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011...10 AM
     FRIDAY TO 10 PM FRIDAY.

     WIND ADVISORY...INZ019...10 AM FRIDAY TO 7 PM FRIDAY.

LM...GALE WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 PM FRIDAY TO
     4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-
     LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-
     LMZ878...3 AM FRIDAY TO 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ563...1 AM FRIDAY TO 10
     PM FRIDAY.

     GALE WARNING...LMZ740...4 AM FRIDAY TO 4 AM SATURDAY.

     STORM WARNING...LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...4 AM FRIDAY
     TO 7 PM FRIDAY.

&&

$$

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

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000
FXUS63 KILX 302001
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
301 PM CDT Thu Oct 30 2014

.SHORT TERM...(Tonight)
ISSUED AT 300 PM CDT THU OCT 30 2014

Two waves impacting the short term.  The first low is over western
Missouri and weak lift associated with weak frontogenesis sparking
some showers for the region.  Plenty of dry air in the area is also
helping to erode the showers and keep them more scattered in
nature.  Cooler air on the way, with another shot of cold air
deepening the trof aloft with the next wave later this evening.
This second wave acting a bit more like a cold front with the wind
shift to more north/northwesterly winds tonight and cold air, but
the models are having a hard time with precip.  Current precip is
overblown in the models, and the later wave (after midnight) is even
more sketchy with QPF.  As a result, pops are minimal in association
with the second wave...and instead follow the progression of the
current precip out to the east by midnight. Temps currently on the
cooler side of guidance as the temps have not dropped far enough in
the last 24 hours and that trend may continue, though the RH will be
plenty for clouds, if not for ongoing precip. Tightening pressure
gradient behind the boundary resulting in winds ramping up in the
early morning hours in advance of a blustery cold day.


&&

.LONG TERM...(Friday through Thursday)
ISSUED AT 300 PM CDT THU OCT 30 2014

A vigorous cold Canadian shortwave will drop southward into the
Midwest by Friday morning. A strong cold front with this feature
will usher in much colder air to central Illinois for Friday, with
highs only reaching the 40s. North-northwest winds 20-30 mph with
gusts 35-40 mph will develop along and behind the cold front,
bringing wind chills into the 30s for the afternoon. Little
precipitation will remain behind the front, however slight chances
will remain near the IL/IN border. Forecast soundings in this area
indicate wet bulb temperatures below freezing to ground level below
the precipitation generation level, and this should allow for light
snow or mixed rain and snow reaching the ground Friday afternoon and
evening. Breezy and cold conditions will continue into the evening
for Halloween Trick or Treat conditions with temperatures dropping
quickly into the 30s and wind chill values into the 20s.

Friday night, light north winds will continue, while the cold air
mass results in temperatures reaching 25-30 degrees for the first
widespread freeze of the season. Have issued a freeze warning to
account for this.

Little warming is expected through Sunday morning, with another
freezing night expected. A mild and moist southwesterly low level
flow will develop late in the weekend through early next week as an
upper level ridge shifts eastward across Illinois and a deep trough
crosses the Rockies. This trough will bring good chances of showers
late Monday through tuesday night as the system moves into the Ohio
river valley. Isolated thunderstorms may also occur Monday night and
Tue south of I-72. Drier weather is expected Wed night and Thu as
dry northwesterly flow trails the system.


&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 1210 PM CDT THU OCT 30 2014
Mostly VFR through the forecast period. Main issues will be the
afternoon showers that are out there currently. SPI may see a
shower early this afternoon...but the majority of the showers are
scattered, and in concert with a dry low level...will be eroding
somewhat. Main wave/front moving in overnight, bringing a second
chance for showers, though coverage is varied in the models, with
the NAM far drier with the front than the GFS. The HRRR is
starting to come in somewhere in between the two, but taking the
higher RH in the low levels and producing a swath of MVFR clouds
with the fropa. Will take that into account as well and drop the
cigs to the MVFR/VFR break point. Increasing gradient early behind
the boundary picking up the winds in the morning, well ahead of
normal timing for a mix down. Breezy 15-20kt northerly winds
ramping up by 12z.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING from Midnight Friday Night to 9 AM CDT Saturday
FOR ILZ027>031-036>038-040>057-061>063-066>068-071>073.

&&

$$

SHORT TERM...HJS
LONG TERM...Onton
AVIATION...HJS







000
FXUS63 KLOT 301951
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
250 PM CDT THU OCT 30 2014

.UPDATE...
1059 AM CDT

GOING FORECAST FOR THE REST OF TODAY LOOKS FAIRLY ON TRACK WITH
ONLY SMALL ADJUSTMENTS. THE EMPHASIS ON THE FORECAST CONTINUES TO
BE ON THE STRONG AUTUMN SYSTEM FRIDAY.

THE AREA FINDS ITSELF BETWEEN TWO SHORT WAVE DISTURBANCES LATE
THIS MORNING AND AS A RESULT A THINNING IN CLOUD COVER HAS BEEN
SEEN ACROSS NORTHEAST IL AND NORTHWEST IN. EXPECTING VARIABILITY
IN SKY TO OCCUR THE REST OF THE DAY THAT WILL PROBABLY AVERAGE OUT
TO MOSTLY CLOUDY. THIS BREAK HAS ALLOWED TEMPERATURES IN SOME
PLACES TO OUTPACE PREVIOUS FORECAST AND HAVE ADJUSTED HIGHS UP A
DEGREE TO TWO IN EASTERN AREAS. WEAKER LESS ORGANIZED FORCING
BETWEEN THE TWO WAVES SHOULD CONTINUE TO KEEP ANY RAIN LIGHT OR
EVEN JUST SPRINKLES...WITH THE BETTER CHANCE FOR A FEW HUNDREDTHS
OF AN INCH BEING SOUTH OF I-80 WITH THE SOUTHERN DISTURBANCE THIS
AFTERNOON.

LOOKING AHEAD TO FRIDAY...THE WINDY DAY AND EVENING CONTINUES ON
TRACK WITH THE HIGHEST WIND SPEEDS AND IMPACTS BEING NEAR THE
LAKE SHORE. THE SETUP FOR LAKE EFFECT SNOW IS CONTINUING TO BE
WEIGHED AND MODEL DIFFERENCES DO EXIST IN THE LOWEST THERMAL
PROFILES. WITH LIKELY MODEST TO TEMPORARY HEAVY PRECIPITATION
RATES GIVEN THE HIGH LAKE-INDUCED INSTABILITY...COULD CERTAINLY
REALIZE PRETTY LOW VISIBILITY IN PARTS OF NORTHWEST INDIANA AND
POSSIBLY ALONG THE COOK COUNTY SHORE AT TIMES FRIDAY IF SNOW CAN
BE THE DOMINANT PRECIPITATION TYPE.

MTF

&&

.SHORT TERM...
343 AM CDT

FOR THE REMAINDER OF THE NIGHT AND INTO THURSDAY MORNING...WEATHER
CONDITIONS WILL REMAIN QUIET ACROSS THE REGION UNTIL A STRONG COLD
FRONT SWEEPS THROUGH THE AREA LATE TONIGHT.

UNDER CLEAR SKIES AND WITH DEWPOINTS IN THE MIDDLE 20S TO LOWER
30S...TEMPERATURES ACROSS THE REGION HAVE BEEN DROPPING FAST
OVERNIGHT UNDER FAVORABLE RADIATIVE COOLING.  HOWEVER...A WEAK
SHORTWAVE DROPPING SEWD THROUGH THE NRN PLAINS AND ACROSS THE MIDDLE
AND UPPER MISSISSIPPI VALLEY WILL BRING INCREASING MID AND HIGH
LEVEL CLOUDINESS...THROUGH THE EARLY MORNING HOURS...TEMPERING THE
TEMPERATURE DROP OFF.  HOWEVER...OVERNIGHT LOW TEMPERATURES WILL
STILL  DROP INTO THE UPPER 20S TO LOWER 30S ACROSS THE AREA AWAY
FROM THE CHICAGO METRO AREA URBAN HEAT ISLAND...WHERE TEMPERATURES
WILL ONLY DROP INTO THE  UPPER 30S TO LOWER 40S.  AT THE
SURFACE...HIGH PRESSURE IS SLIDING SEWD ACROSS THE REGION...KEEPING
WINDS NEAR CALM.  AS THE HIGH SLIDES INTO THE OHIO VALLEY LATER
TODAY...WINDS WILL BECOME MORE WLY...BUT WITH A WEAK GRADIENT IN
PLACE...WINDS SHOULD REMAIN LIGHT THROUGH THE DAY AND INTO THE EARLY
EVENING.  WITH HEIGHT FALLS ASSOCIATED WITH THE PASSAGE OF THE
SHORTWAVE AND A GENERAL COLD ADVECTIVE PATTERN IN PLACE
ALOFT...ANTICIPATE ANOTHER CHILLY DAY WITH HIGHS ONLY IN THE LOWER
TO MIDDLE 50S.

A STRONG COLD FRONT IS EXPECTED TO DROP OUT OF THE NRN PLAINS AND
PUSH INTO NWRN IL BY AROUND MIDNIGHT AND THE QUICKLY PUSH SEWD
ACROSS THE REGION...BRINGING A QUICK WIND SHIFT TO NWLY.  STRONG
COLD ADVECTION AND STRONG PRESSURE RISES OF 6MB/6HR WILL BRING
STRONG...GUSTY WINDS. LATEST FORECAST SOUNDING SHOW WINDS ARND 30
MPH AT THE TOP OF THE MIXED LAYER OVER LAND...WHICH WOULD
SUPPORT GUSTS NEAR 30 MPH AT THE SFC BY ARND DAYBREAK FRIDAY
MORNING.

KREIN

&&

.LONG TERM...
308 AM CDT

STRONG UPPER TROUGH/CLOSED LOW WILL CONTINUE TO DIG SOUTH THROUGH
THE WESTERN LAKES REGION FRIDAY. STRONG COLD AIR ADVECTION AND
TIGHTENING PRESSURE GRADIENT BETWEEN DEVELOPING SFC LOW TO OUR EAST
AND STRENGTHENING SFC HIGH APPROACHING FROM THE NORTHWEST WILL
RESULT IN STRONG NORTHERLY WINDS FRIDAY...ESPECIALLY NEAR THE LAKE.
FORECAST SOUNDINGS SUPPORT GUSTS TO AROUND 40 MPH MOST AREAS
FRIDAY...THOUGH THE LESSER FRICTION AND STRONGER INSTABILITY AND
RESULTANT MIXING NEAR THE LAKE SHOULD SUPPORT WIND GUSTS OF 50+ MPH
NEAR THE LAKE...ESPECIALLY COOK COUNTY AND NW INDIANA SHORE. COULD
BE A MARGINAL HIGH WIND WARNING FOR LAKE SHORE AREAS WITH A SOLID
WIND ADVISORY EVENT LIKELY. GIVEN THE UNCERTAINTY OPTED TO HOLD OFF
ON HEADLINES FOR NOW AND WILL LET LATER SHIFTS DECIDE.

THE FULL FETCH STORM FORCE WINDS WILL RESULT IN 20FT+
WAVES...PARTICULARLY FOR COOK COUNTY INTO NW INDIANA GIVEN THE
350-360 WIND DIRECTION. LAKE LEVELS ARE NEARLY 2 FEET HIGHER THAN
LAST YEAR AND PREVIOUS YEARS...SO EVEN THOUGH WAVES WILL NOT BE
QUITE AS HIGH AS SANDY A FEW YEARS AGO...THE LAKE SHORE FLOODING
IMPACT COULD BE SIMILAR. HAVE GONE AHEAD AND ISSUED A LAKESHORE
FLOOD ADVISORY TO HIGHLIGHT THE LIKELY COASTAL INUNDATION IMPACT
FROM THE LARGE AND BATTERING WAVES.

COULD SEE SOME SHOWERS ALONG THE COLD FRONT TONIGHT...BUT FRONT
SHOULD CLEAR THE AREA BY FRIDAY MORNING WITH SYNOPTIC PRECIP THREAT
LARGELY ENDING. HOWEVER...VERY IMPRESSIVE LAKE EFFECT SET-UP LOOKS
TO DEVELOP FRIDAY INTO FRIDAY EVENING WITH VERY HIGH LAKE INDUCED
EQUILIBRIUM LEVELS UP TO AROUND 20KFT AND UP TO NEARLY -30C. GIVEN
THE LIKELY PRESENCE OF SUPER COOLED LIQUID IN THE CLOUDS AND HIGH
EQUILIBRIUM LEVELS IT SEEMS QUITE LIKELY THAT ISOLATED THUNDERSTORMS
WILL OCCUR IN ADDITION TO FAIRLY WIDESPREAD SHOWERS FRIDAY. THESE
EARLY SEASON LAKE EFFECT EVENTS ARE ALWAYS TRICKY WITH P-TYPE AS THE
VERY COLD AIR ALOFT...AROUND -8 TO -10C AT 850MB WOULD SOLIDLY
SUPPORT SNOW DESPITE WARM WATER TEMPS IN THE 50S STILL. HAVE GONE
WITH RAIN OR SNOW SHOWERS FOR NOW...BUT THINK THE FARTHER INLAND
AWAY FROM THE LAKE YOU GET THE BETTER CHANCE WILL BE FOR ALL SNOW
SHOWERS FRIDAY AFTERNOON AND EVENING INTO NW INDIANA. GIVEN THE
POTENTIAL FOR THUNDERSTORMS AND ADDED DYNAMIC COOLING AM CONCERNED
THAT SOME PORTIONS OF NW INDIANA...ESPECIALLY A BIT INLAND FROM THE
LAKE...COULD END UP WITH A SLUSHY COUPLE INCHES OF SNOW ACCUMULATION
ON GRASSY SURFACES BY FRIDAY EVENING...THOUGH CONFIDENCE IS TOO LOW
TO HIT THAT TOO HARD AT THIS TIME. LOW LEVEL FLOW SHOULD SLOWLY VEER
SO THAT THE FOCUS FOR LAKE EFFECT PRECIP SHOULD START IN PORTER
COUNTY EARLY FRIDAY AND GRADUALLY SHIFT WEST INTO LAKE COUNTY
INDIANA FRIDAY AFTERNOON AND POTENTIALLY INTO SOUTHEAST COOK COUNTY
FRIDAY EVENING BEFORE INVERSION HEIGHTS CRASH AND LAKE EFFECT WINDS
DOWN LATE FRIDAY NIGHT.

THE COMBINATION OF STRONG WINDS AND UNSEASONABLY COLD TEMPS WILL
SEND WIND CHILLS DROPPING INTO THE 20S DURING TRICK OR TREATING
HOURS FRIDAY EVENING...WITH EVEN LESS FAVORABLE TRICK OR TREATING
WEATHER IN NW INDIANA UNDER THE LAKE EFFECT RAIN/SNOW SHOWERS. AFTER
THE UNSEASONABLY COLD TEMPERATURES AND WIND CHILLS FRIDAY INTO
FRIDAY NIGHT...LOOK FOR QUIET CONDITIONS OVER THE WEEKEND WITH VERY
SLOWLY MODERATING TEMPERATURES. PROGRESSIVE PATTERN SHOULD RESULT IN
TRANSIENT RIDGE MOVING EAST OF THE AREA EARLY NEXT WEEK WITH NEXT
SYSTEM BRINGING THE POTENTIAL FOR SHOWERS MONDAY NIGHT INTO TUESDAY.
TEMPERATURES SHOULD BE CLOSER TO SEASONAL NORMAL NEXT WEEK RETURNING
TO WHAT WILL FEEL LIKE THE RATHER PLEASANT 50S FOLLOWING FRIDAY`S
FLIRTATION WITH WINTER-LIKE TEMPERATURES.

IZZI

&&

.AVIATION...

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

* NO ISSUES IN THE NEAR TERM.

* SOUTHWEST WINDS SHIFTING TO THE NORTHWEST WITH FROPA
  TONIGHT...WITH GUSTS INCREASING THROUGH MIDDAY FRIDAY WHILE
  BECOMING MORE NORTHERLY.

* CHANCE OF -SHRA/-SHSN TONIGHT THROUGH EARLY FRIDAY MORNING.

* MVFR CEILINGS LATE TONIGHT INTO FRIDAY MORNING.

RODRIGUEZ

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

RELATIVELY QUIET CONDITIONS EARLY THIS AFTERNOON WILL CONTINUE THIS
AFTERNOON...WHILE SOUTHWEST WINDS PREVAIL AND MID/HIGH LEVEL CLOUD
COVER CONTINUE TO STREAM OVERHEAD. CONDITIONS WILL BEGIN
DETERIORATING TONIGHT AS SYSTEM/FRONT PUSH THROUGH THE REGION. THE
CURRENT SOUTHWEST WINDS WILL TURN WEST AND NORTHWEST TONIGHT WITH
WIND SPEED/GUSTS QUICKLY INCREASING. LOWERING CEILINGS TO MVFR WILL
ALSO OCCUR WITH THE ARRIVAL OF THIS WIND SHIFT...LIKELY PERSISTING
FOR MUCH OF FRIDAY MORNING. MOISTURE WILL ALSO BE SUFFICIENT FOR
RAIN SHOWERS TO INITIALLY BE POSSIBLE BUT WITH MUCH COLDER AIR
QUICKLY FILTERING IN...SNOW SHOWERS WILL THEN BE POSSIBLE. EXPECT
THESE RAIN/SNOW SHOWERS TO BE ON THE LIGHTER SIDE...WITH NO VIS
RESTRICTION EXPECTED AS WELL AS NO SNOW ACCUMULATION. THE WINDS WILL
CONTINUE TO SHIFT MORE NORTHERLY FRIDAY MORNING AND LIKELY REMAIN IN
THIS NORTH DIRECTION FOR MUCH OF FRIDAY. THIS ORIENTATION WILL
COINCIDE WITH VERY STRONG WINDS...WITH GUSTS ANTICIPATED TO BE
AROUND 40 KT. CONDITIONS SHOULD BE BACK TO VFR FOR THE REMAINDER OF
THE DAY/FORECAST PERIOD...BUT A TREND BACK TOWARDS DETERIORATING
CONDITIONS COULD BE POSSIBLE IF LAKE EFFECT PRECIP AND CLOUD COVER
MOVE TOWARDS THE TERMINALS FRIDAY EVENING.

RODRIGUEZ

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

* HIGH CONFIDENCE OF VFR CONDITIONS IN THE NEAR TERM.

* HIGH CONFIDENCE OF WIND DIRECTION AND SPEED/GUSTS...MEDIUM HIGH
  CONFIDENCE OF EXACT TIMING OF FROPA.

* HIGH CONFIDENCE OF -SHRA/-SHSN...MEDIUM CONFIDENCE OF DURATION.

* HIGH CONFIDENCE OF MVFR CEILINGS...MEDIUM CONFIDENCE OF DURATION.

RODRIGUEZ

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

* FRIDAY NIGHT...STRONG NORTH WINDS GUSTING TO 30 KT. CHANCE OF
  SHRA OR SHSN.

* SATURDAY...VFR. WX NIL. NORTHEAST WINDS 10-15KT.

* SUNDAY...VFR. WX NIL. SOUTH WINDS.

* MONDAY...CHANCE OF SHRA. GUSTY SOUTHERLY WINDS.

* TUESDAY...CHANCE OF SHRA. WESTERLY WINDS.

* WEDNESDAY...VFR. WX NIL. SOUTHWEST WINDS.

&&

.MARINE...
250 PM CDT

A VERY ACTIVE PERIOD OVER LAKE MICHIGAN BEGINNING LATER TONIGHT. THE
AREA WILL FIND ITSELF IN A FAVORABLE AND ANOMALOUS SYNOPTIC WEATHER
PATTERN FOR STRONG NORTHERLY WINDS...AND THIS WILL BE FURTHER AIDED
BY THE WARM WATERS/EXTREME INSTABILITY TO PRODUCE REGULAR HIGHER END
STORM FORCE GUSTS PERSISTING INTO FRIDAY. A STRONG COLD FRONT WILL
MOVE DOWN THE LAKE RAPIDLY FROM AROUND MIDNIGHT THROUGH 5 AM.
IMMEDIATELY BEHIND THIS A VERY TIGHT PRESSURE GRADIENT IN SYNC WITH
COLD AIR ADVECTION WILL PRODUCE A RAMP UP IN NORTHERLY WIND SPEEDS.
THE HIGHEST WIND SPEEDS OF STORM FORCE TO 50 AND POSSIBLY EVEN 55 KT
ARE EXPECTED LATE TONIGHT THROUGH MID FRIDAY AFTERNOON FOR THE
CENTRAL AND SOUTHERN PART OF THE LAKE...AND AFTER DAYBREAK THROUGH
THE DAY ON FRIDAY FOR THE NEARSHORE AREAS OF ILLINOIS AND INDIANA.
THE WAVE MAXIMUM OF OVER 20 FOOTERS IS EXPECTED TO DEVELOP OVER THE
CENTRAL PART OF THE LAKE EARLY FRIDAY MORNING AND EVOLVE SOUTHWARD
REACHING THE ILLINOIS AND INDIANA NEARSHORE FRIDAY AFTERNOON AND
EARLY EVENING. WAVES WILL BE VERY SLOW TO SUBSIDE THROUGH LATE
FRIDAY NIGHT AND EARLY SATURDAY. HIGH PRESSURE WILL MOVE QUICKLY
OVER THE LAKE SATURDAY NIGHT BEFORE SOUTHERLY FLOW RETURNS TO THE
LAKE.

MTF

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ741-LMZ742-
     LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-
     LMZ876-LMZ878...7 PM FRIDAY TO 4 AM SATURDAY.

     STORM WARNING...
LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ741-LMZ742-
     LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-
     LMZ876-LMZ878...6 AM FRIDAY TO 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
     LMZ868...1 AM FRIDAY TO 10 PM FRIDAY.

     GALE WARNING...LMZ740...6 AM FRIDAY TO 4 AM SATURDAY.

&&

$$

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

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








000
FXUS63 KLOT 301821
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
120 PM CDT THU OCT 30 2014

.UPDATE...
1059 AM CDT

GOING FORECAST FOR THE REST OF TODAY LOOKS FAIRLY ON TRACK WITH
ONLY SMALL ADJUSTMENTS. THE EMPHASIS ON THE FORECAST CONTINUES TO
BE ON THE STRONG AUTUMN SYSTEM FRIDAY.

THE AREA FINDS ITSELF BETWEEN TWO SHORT WAVE DISTURBANCES LATE
THIS MORNING AND AS A RESULT A THINNING IN CLOUD COVER HAS BEEN
SEEN ACROSS NORTHEAST IL AND NORTHWEST IN. EXPECTING VARIABILITY
IN SKY TO OCCUR THE REST OF THE DAY THAT WILL PROBABLY AVERAGE OUT
TO MOSTLY CLOUDY. THIS BREAK HAS ALLOWED TEMPERATURES IN SOME
PLACES TO OUTPACE PREVIOUS FORECAST AND HAVE ADJUSTED HIGHS UP A
DEGREE TO TWO IN EASTERN AREAS. WEAKER LESS ORGANIZED FORCING
BETWEEN THE TWO WAVES SHOULD CONTINUE TO KEEP ANY RAIN LIGHT OR
EVEN JUST SPRINKLES...WITH THE BETTER CHANCE FOR A FEW HUNDREDTHS
OF AN INCH BEING SOUTH OF I-80 WITH THE SOUTHERN DISTURBANCE THIS
AFTERNOON.

LOOKING AHEAD TO FRIDAY...THE WINDY DAY AND EVENING CONTINUES ON
TRACK WITH THE HIGHEST WIND SPEEDS AND IMPACTS BEING NEAR THE
LAKE SHORE. THE SETUP FOR LAKE EFFECT SNOW IS CONTINUING TO BE
WEIGHED AND MODEL DIFFERENCES DO EXIST IN THE LOWEST THERMAL
PROFILES. WITH LIKELY MODEST TO TEMPORARY HEAVY PRECIPITATION
RATES GIVEN THE HIGH LAKE-INDUCED INSTABILITY...COULD CERTAINLY
REALIZE PRETTY LOW VISIBILITY IN PARTS OF NORTHWEST INDIANA AND
POSSIBLY ALONG THE COOK COUNTY SHORE AT TIMES FRIDAY IF SNOW CAN
BE THE DOMINANT PRECIPITATION TYPE.

MTF

&&

.SHORT TERM...
343 AM CDT

FOR THE REMAINDER OF THE NIGHT AND INTO THURSDAY MORNING...WEATHER
CONDITIONS WILL REMAIN QUIET ACROSS THE REGION UNTIL A STRONG COLD
FRONT SWEEPS THROUGH THE AREA LATE TONIGHT.

UNDER CLEAR SKIES AND WITH DEWPOINTS IN THE MIDDLE 20S TO LOWER
30S...TEMPERATURES ACROSS THE REGION HAVE BEEN DROPPING FAST
OVERNIGHT UNDER FAVORABLE RADIATIVE COOLING.  HOWEVER...A WEAK
SHORTWAVE DROPPING SEWD THROUGH THE NRN PLAINS AND ACROSS THE MIDDLE
AND UPPER MISSISSIPPI VALLEY WILL BRING INCREASING MID AND HIGH
LEVEL CLOUDINESS...THROUGH THE EARLY MORNING HOURS...TEMPERING THE
TEMPERATURE DROP OFF.  HOWEVER...OVERNIGHT LOW TEMPERATURES WILL
STILL  DROP INTO THE UPPER 20S TO LOWER 30S ACROSS THE AREA AWAY
FROM THE CHICAGO METRO AREA URBAN HEAT ISLAND...WHERE TEMPERATURES
WILL ONLY DROP INTO THE  UPPER 30S TO LOWER 40S.  AT THE
SURFACE...HIGH PRESSURE IS SLIDING SEWD ACROSS THE REGION...KEEPING
WINDS NEAR CALM.  AS THE HIGH SLIDES INTO THE OHIO VALLEY LATER
TODAY...WINDS WILL BECOME MORE WLY...BUT WITH A WEAK GRADIENT IN
PLACE...WINDS SHOULD REMAIN LIGHT THROUGH THE DAY AND INTO THE EARLY
EVENING.  WITH HEIGHT FALLS ASSOCIATED WITH THE PASSAGE OF THE
SHORTWAVE AND A GENERAL COLD ADVECTIVE PATTERN IN PLACE
ALOFT...ANTICIPATE ANOTHER CHILLY DAY WITH HIGHS ONLY IN THE LOWER
TO MIDDLE 50S.

A STRONG COLD FRONT IS EXPECTED TO DROP OUT OF THE NRN PLAINS AND
PUSH INTO NWRN IL BY AROUND MIDNIGHT AND THE QUICKLY PUSH SEWD
ACROSS THE REGION...BRINGING A QUICK WIND SHIFT TO NWLY.  STRONG
COLD ADVECTION AND STRONG PRESSURE RISES OF 6MB/6HR WILL BRING
STRONG...GUSTY WINDS. LATEST FORECAST SOUNDING SHOW WINDS ARND 30
MPH AT THE TOP OF THE MIXED LAYER OVER LAND...WHICH WOULD
SUPPORT GUSTS NEAR 30 MPH AT THE SFC BY ARND DAYBREAK FRIDAY
MORNING.

KREIN

&&

.LONG TERM...
308 AM CDT

STRONG UPPER TROUGH/CLOSED LOW WILL CONTINUE TO DIG SOUTH THROUGH
THE WESTERN LAKES REGION FRIDAY. STRONG COLD AIR ADVECTION AND
TIGHTENING PRESSURE GRADIENT BETWEEN DEVELOPING SFC LOW TO OUR EAST
AND STRENGTHENING SFC HIGH APPROACHING FROM THE NORTHWEST WILL
RESULT IN STRONG NORTHERLY WINDS FRIDAY...ESPECIALLY NEAR THE LAKE.
FORECAST SOUNDINGS SUPPORT GUSTS TO AROUND 40 MPH MOST AREAS
FRIDAY...THOUGH THE LESSER FRICTION AND STRONGER INSTABILITY AND
RESULTANT MIXING NEAR THE LAKE SHOULD SUPPORT WIND GUSTS OF 50+ MPH
NEAR THE LAKE...ESPECIALLY COOK COUNTY AND NW INDIANA SHORE. COULD
BE A MARGINAL HIGH WIND WARNING FOR LAKE SHORE AREAS WITH A SOLID
WIND ADVISORY EVENT LIKELY. GIVEN THE UNCERTAINTY OPTED TO HOLD OFF
ON HEADLINES FOR NOW AND WILL LET LATER SHIFTS DECIDE.

THE FULL FETCH STORM FORCE WINDS WILL RESULT IN 20FT+
WAVES...PARTICULARLY FOR COOK COUNTY INTO NW INDIANA GIVEN THE
350-360 WIND DIRECTION. LAKE LEVELS ARE NEARLY 2 FEET HIGHER THAN
LAST YEAR AND PREVIOUS YEARS...SO EVEN THOUGH WAVES WILL NOT BE
QUITE AS HIGH AS SANDY A FEW YEARS AGO...THE LAKE SHORE FLOODING
IMPACT COULD BE SIMILAR. HAVE GONE AHEAD AND ISSUED A LAKESHORE
FLOOD ADVISORY TO HIGHLIGHT THE LIKELY COASTAL INUNDATION IMPACT
FROM THE LARGE AND BATTERING WAVES.

COULD SEE SOME SHOWERS ALONG THE COLD FRONT TONIGHT...BUT FRONT
SHOULD CLEAR THE AREA BY FRIDAY MORNING WITH SYNOPTIC PRECIP THREAT
LARGELY ENDING. HOWEVER...VERY IMPRESSIVE LAKE EFFECT SET-UP LOOKS
TO DEVELOP FRIDAY INTO FRIDAY EVENING WITH VERY HIGH LAKE INDUCED
EQUILIBRIUM LEVELS UP TO AROUND 20KFT AND UP TO NEARLY -30C. GIVEN
THE LIKELY PRESENCE OF SUPER COOLED LIQUID IN THE CLOUDS AND HIGH
EQUILIBRIUM LEVELS IT SEEMS QUITE LIKELY THAT ISOLATED THUNDERSTORMS
WILL OCCUR IN ADDITION TO FAIRLY WIDESPREAD SHOWERS FRIDAY. THESE
EARLY SEASON LAKE EFFECT EVENTS ARE ALWAYS TRICKY WITH P-TYPE AS THE
VERY COLD AIR ALOFT...AROUND -8 TO -10C AT 850MB WOULD SOLIDLY
SUPPORT SNOW DESPITE WARM WATER TEMPS IN THE 50S STILL. HAVE GONE
WITH RAIN OR SNOW SHOWERS FOR NOW...BUT THINK THE FARTHER INLAND
AWAY FROM THE LAKE YOU GET THE BETTER CHANCE WILL BE FOR ALL SNOW
SHOWERS FRIDAY AFTERNOON AND EVENING INTO NW INDIANA. GIVEN THE
POTENTIAL FOR THUNDERSTORMS AND ADDED DYNAMIC COOLING AM CONCERNED
THAT SOME PORTIONS OF NW INDIANA...ESPECIALLY A BIT INLAND FROM THE
LAKE...COULD END UP WITH A SLUSHY COUPLE INCHES OF SNOW ACCUMULATION
ON GRASSY SURFACES BY FRIDAY EVENING...THOUGH CONFIDENCE IS TOO LOW
TO HIT THAT TOO HARD AT THIS TIME. LOW LEVEL FLOW SHOULD SLOWLY VEER
SO THAT THE FOCUS FOR LAKE EFFECT PRECIP SHOULD START IN PORTER
COUNTY EARLY FRIDAY AND GRADUALLY SHIFT WEST INTO LAKE COUNTY
INDIANA FRIDAY AFTERNOON AND POTENTIALLY INTO SOUTHEAST COOK COUNTY
FRIDAY EVENING BEFORE INVERSION HEIGHTS CRASH AND LAKE EFFECT WINDS
DOWN LATE FRIDAY NIGHT.

THE COMBINATION OF STRONG WINDS AND UNSEASONABLY COLD TEMPS WILL
SEND WIND CHILLS DROPPING INTO THE 20S DURING TRICK OR TREATING
HOURS FRIDAY EVENING...WITH EVEN LESS FAVORABLE TRICK OR TREATING
WEATHER IN NW INDIANA UNDER THE LAKE EFFECT RAIN/SNOW SHOWERS. AFTER
THE UNSEASONABLY COLD TEMPERATURES AND WIND CHILLS FRIDAY INTO
FRIDAY NIGHT...LOOK FOR QUIET CONDITIONS OVER THE WEEKEND WITH VERY
SLOWLY MODERATING TEMPERATURES. PROGRESSIVE PATTERN SHOULD RESULT IN
TRANSIENT RIDGE MOVING EAST OF THE AREA EARLY NEXT WEEK WITH NEXT
SYSTEM BRINGING THE POTENTIAL FOR SHOWERS MONDAY NIGHT INTO TUESDAY.
TEMPERATURES SHOULD BE CLOSER TO SEASONAL NORMAL NEXT WEEK RETURNING
TO WHAT WILL FEEL LIKE THE RATHER PLEASANT 50S FOLLOWING FRIDAY`S
FLIRTATION WITH WINTER-LIKE TEMPERATURES.

IZZI

&&

.AVIATION...

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

* NO ISSUES IN THE NEAR TERM.

* SOUTHWEST WINDS SHIFTING TO THE NORTHWEST WITH FROPA
  TONIGHT...WITH GUSTS INCREASING THROUGH MIDDAY FRIDAY WHILE
  BECOMING MORE NORTHERLY.

* CHANCE OF -SHRA/-SHSN TONIGHT THROUGH EARLY FRIDAY MORNING.

* MVFR CEILINGS LATE TONIGHT INTO FRIDAY MORNING.

RODRIGUEZ

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

RELATIVELY QUIET CONDITIONS EARLY THIS AFTERNOON WILL CONTINUE THIS
AFTERNOON...WHILE SOUTHWEST WINDS PREVAIL AND MID/HIGH LEVEL CLOUD
COVER CONTINUE TO STREAM OVERHEAD. CONDITIONS WILL BEGIN
DETERIORATING TONIGHT AS SYSTEM/FRONT PUSH THROUGH THE REGION. THE
CURRENT SOUTHWEST WINDS WILL TURN WEST AND NORTHWEST TONIGHT WITH
WIND SPEED/GUSTS QUICKLY INCREASING. LOWERING CEILINGS TO MVFR WILL
ALSO OCCUR WITH THE ARRIVAL OF THIS WIND SHIFT...LIKELY PERSISTING
FOR MUCH OF FRIDAY MORNING. MOISTURE WILL ALSO BE SUFFICIENT FOR
RAIN SHOWERS TO INITIALLY BE POSSIBLE BUT WITH MUCH COLDER AIR
QUICKLY FILTERING IN...SNOW SHOWERS WILL THEN BE POSSIBLE. EXPECT
THESE RAIN/SNOW SHOWERS TO BE ON THE LIGHTER SIDE...WITH NO VIS
RESTRICTION EXPECTED AS WELL AS NO SNOW ACCUMULATION. THE WINDS WILL
CONTINUE TO SHIFT MORE NORTHERLY FRIDAY MORNING AND LIKELY REMAIN IN
THIS NORTH DIRECTION FOR MUCH OF FRIDAY. THIS ORIENTATION WILL
COINCIDE WITH VERY STRONG WINDS...WITH GUSTS ANTICIPATED TO BE
AROUND 40 KT. CONDITIONS SHOULD BE BACK TO VFR FOR THE REMAINDER OF
THE DAY/FORECAST PERIOD...BUT A TREND BACK TOWARDS DETERIORATING
CONDITIONS COULD BE POSSIBLE IF LAKE EFFECT PRECIP AND CLOUD COVER
MOVE TOWARDS THE TERMINALS FRIDAY EVENING.

RODRIGUEZ

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

* HIGH CONFIDENCE OF VFR CONDITIONS IN THE NEAR TERM.

* HIGH CONFIDENCE OF WIND DIRECTION AND SPEED/GUSTS...MEDIUM HIGH
  CONFIDENCE OF EXACT TIMING OF FROPA.

* HIGH CONFIDENCE OF -SHRA/-SHSN...MEDIUM CONFIDENCE OF DURATION.

* HIGH CONFIDENCE OF MVFR CEILINGS...MEDIUM CONFIDENCE OF DURATION.

RODRIGUEZ

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

* FRIDAY NIGHT...STRONG NORTH WINDS GUSTING TO 30 KT. CHANCE OF
  SHRA OR SHSN.

* SATURDAY...VFR. WX NIL. NORTHEAST WINDS 10-15KT.

* SUNDAY...VFR. WX NIL. SOUTH WINDS.

* MONDAY...CHANCE OF SHRA. GUSTY SOUTHERLY WINDS.

* TUESDAY...CHANCE OF SHRA. WESTERLY WINDS.

* WEDNESDAY...VFR. WX NIL. SOUTHWEST WINDS.

&&

.MARINE...
319 AM CDT

SHARP UPPER TROUGH WILL DIG INTO THE WESTERN GREAT LAKES REGION
TONIGHT AND RESULT IN SURFACE LOW DEVELOPING AND SLOWLY INTENSIFYING
TONIGHT INTO FRIDAY OVER THE EASTERN LAKES. MEANWHILE...UPSTREAM
HIGH PRESSURE OVER THE CANADIAN PRAIRIES WILL STRENGTHEN AS IT MOVES
SOUTHEAST INTO THE NORTHERN PLAINS TONIGHT INTO FRIDAY. THE RESULT
WILL BE A VERY TIGHT PRESSURE GRADIENT DEVELOPING OVER THE AREA
LATER TONIGHT INTO FRIDAY AND WHEN COMBINED WITH THE EXTREME
INSTABILITY LIKELY TO DEVELOP AS A RESULT OF THE VERY COLD AIR ALOFT
MOVING IN...AM EXPECTING A PERIOD OF HIGH END GALES TO LOW END STORM
FORCE WINDS OVER THE LAKE LATE TONIGHT THROUGH FRIDAY NIGHT. CURRENT
INDICATIONS ARE THAT THE LONGEST DURATION AND HIGHEST PROBABILITY OF
STORM FORCE WINDS WILL EXIST OVER SOUTHERN LAKE MICHIGAN AND HAVE
OPTED TO UPGRADE TO A STORM WARNING THERE FOR FRIDAY...INCLUDING THE
NORTHWEST INDIANA NEARSHORE WATERS UP TO NORTHERLY ISLAND IN THE
ILLINOIS NEARSHORE. THE NORTHERN PORTIONS OF THE ILLINOIS NEARSHORE
MAY END UP WITH A MORE OFFSHORE FETCH IN THE 350-360 RANGE LESSENING
THE THREAT OF STORM FORCE WINDS A BIT. NORTHERN PORTIONS OF THE LAKE
COULD SEE STORM FORCE GUSTS FOR A TIME FRIDAY MORNING BUT DURATION
LOOKS TO BE LESS AND CONFIDENCE LOWER...SO JUST HINTED AT THIS
THREAT IN THE GLF. FULL FETCH NORTH STORM FORCE WINDS SHOULD HAVE NO
PROBLEM KICKING WAVES UP TO AROUND OR JUST ABOVE 20 FT OVER SOUTHERN
PORTIONS OF THE LAKE FRIDAY AFTERNOON AND EVENING. WINDS SHOULD
SUBSIDE RATHER QUICKLY FRIDAY NIGHT INTO SATURDAY AS THE PATTERN
REMAINS PROGRESSIVE AND THE HIGH PRESSURE RESPONSIBLE FOR THE STORM
EVENT MOVES INTO THE WESTERN LAKES REGION ALLOWING WINDS AND
EVENTUALLY WAVES TO SUBSIDE SATURDAY. LATER SUNDAY INTO EARLY NEXT
WEEK 25-30KT SOUTHERLY WINDS COULD DEVELOP AS HIGH PUSHES OFF TO THE
EAST AND NEW LOW PRESSURE DEVELOPS OVER THE NORTHERN PLAINS.

IZZI

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ741-LMZ742-
     LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-
     LMZ876-LMZ878...7 PM FRIDAY TO 4 AM SATURDAY.

     STORM WARNING...
LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ741-LMZ742-
     LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-
     LMZ876-LMZ878...6 AM FRIDAY TO 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
     LMZ868...1 AM FRIDAY TO 10 PM FRIDAY.

     GALE WARNING...LMZ740...6 AM FRIDAY TO 4 AM SATURDAY.

&&

$$

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

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









000
FXUS63 KILX 301721
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1221 PM CDT Thu Oct 30 2014

.UPDATE...
ISSUED AT 1036 AM CDT THU OCT 30 2014
Small wave moving into the Midwest this morning bringing some
showers across Missouri and into Illinois. Some rain showers
moving into the Jacksonville area early. Have adjusted the pops
for the next few hours for some showers in west central Illinois,
but plenty of dry air in the region will probably help to keep any
widespread precip at bay. Temperatures doing well with minimal
cloud cover to the east ahead of the scattered showers. No major
updates required, but have freshened up the hourly grids as well
as the pops in the short term.

&&

.SHORT TERM...(Today)
ISSUED AT 331 AM CDT THU OCT 30 2014

High pressure centered over the area will slowly drift east today
and give way to a weather system approaching from the west. This low
pressure area will move east and then southeast while another low
pressure area moves across the Great Lakes region. Both of these are
associated with an upper level trough that will be moving through
the area today. These features will not have a lot of moisture to
work with, but will bring a chance of showers to the CWA today. Pops
will be only in the chance category and not expecting any
thunderstorms at this time. Light winds this morning will become
southeast, and then easterly during the afternoon. Wind speeds
should be around 5 to 10 mph.

MOS guidance looks ok, but MAV looks a little warm in the southeast
given the expected cloud cover and chance of pcpn. So, mid to upper
50s looks reasonable for today.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 331 AM CDT THU OCT 30 2014

An extended period of below normal temperatures is still expected
across central and southeast Illinois into next week. The coldest
period will extend from Friday to Sunday, with a hard freeze likely
early Saturday and Sunday mornings. A bit too early for a Freeze
Watch being 4th and 6th periods, but will issue a special weather
statement to address the the freezing conditions that will likely
end the growing season. This will be the first hard freeze across
the forecast area and running about two weeks later than normal.
Halloween Trick or Treat conditions will be less than ideal with
actual temperatures in the upper 30s or lower 40s and wind chill
values in the upper 20s and lower 30s late Friday afternoon into
early Friday evening with blustery north winds gusting to around
35 mph at times Friday afternoon.

The short wave that tracks across MO and sw IL by sunset, and into
the mid MS river valley by midnight tonight, and into western KY/TN
by dawn Fri, will linger chances of rain showers especially over
southeast IL. A much stronger northern stream short wave, currently
diving into Saskatchewan and Manitoba, will track across the Great
Lakes/Midwest on Friday. Most of the moisture will be east of IL
Friday and Friday night and just have small chances of light rain
showers in far eastern IL Friday and then mixes with or changes to
light snow by Friday evening over IN. However, this system will be
accompanied by gusty north winds of 20-25 mph and gusts of 25 to 40
mph and will help usher in the airmass that will provide our hard
freeze for Friday and Saturday nights with lows 25-30F both nights.

Upper level ridging will shift eastward into IL late in the weekend
into early next week with temperatures modifying Mon-Wed with highs
in the mid 50s to lower 60s. The ridge will shift east of IL later
Monday into Tue while strong upper level low/trof digs into the
southern Rockies. This puts IL in an unsettled upper level sw flow
and increasing chances of showers Mon-Tue night as a frontal system
sets up from the southern plains ne into the Ohio river valley.
Isolated thunderstorms may also occur Monday night and Tue south of
I-72. Best rain chances will shift se into the Ohio river valley Wed
and lingered 20-30% chances of showers over southeast IL. Drier
weather expected Wed night and Thu with highs still in the 50s on
Thu.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 1210 PM CDT THU OCT 30 2014
Mostly VFR through the forecast period. Main issues will be the
afternoon showers that are out there currently. SPI may see a
shower early this afternoon...but the majority of the showers are
scattered, and in concert with a dry low level...will be eroding
somewhat. Main wave/front moving in overnight, bringing a second
chance for showers, though coverage is varied in the models, with
the NAM far drier with the front than the GFS. The HRRR is
starting to come in somewhere in between the two, but taking the
higher RH in the low levels and producing a swath of MVFR clouds
with the fropa. Will take that into account as well and drop the
cigs to the MVFR/VFR break point. Increasing gradient early behind
the boundary picking up the winds in the morning, well ahead of
normal timing for a mix down. Breezy 15-20kt northerly winds
ramping up by 12z.

&&

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

$$

UPDATE...HJS
SHORT TERM...Auten
LONG TERM...07
AVIATION...HJS







000
FXUS63 KLOT 301604
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1104 AM CDT THU OCT 30 2014

.UPDATE...
1059 AM CDT

GOING FORECAST FOR THE REST OF TODAY LOOKS FAIRLY ON TRACK WITH
ONLY SMALL ADJUSTMENTS. THE EMPHASIS ON THE FORECAST CONTINUES TO
BE ON THE STRONG AUTUMN SYSTEM FRIDAY.

THE AREA FINDS ITSELF BETWEEN TWO SHORT WAVE DISTURBANCES LATE
THIS MORNING AND AS A RESULT A THINNING IN CLOUD COVER HAS BEEN
SEEN ACROSS NORTHEAST IL AND NORTHWEST IN. EXPECTING VARIABILITY
IN SKY TO OCCUR THE REST OF THE DAY THAT WILL PROBABLY AVERAGE OUT
TO MOSTLY CLOUDY. THIS BREAK HAS ALLOWED TEMPERATURES IN SOME
PLACES TO OUTPACE PREVIOUS FORECAST AND HAVE ADJUSTED HIGHS UP A
DEGREE TO TWO IN EASTERN AREAS. WEAKER LESS ORGANIZED FORCING
BETWEEN THE TWO WAVES SHOULD CONTINUE TO KEEP ANY RAIN LIGHT OR
EVEN JUST SPRINKLES...WITH THE BETTER CHANCE FOR A FEW HUNDREDTHS
OF AN INCH BEING SOUTH OF I-80 WITH THE SOUTHERN DISTURBANCE THIS
AFTERNOON.

LOOKING AHEAD TO FRIDAY...THE WINDY DAY AND EVENING CONTINUES ON
TRACK WITH THE HIGHEST WIND SPEEDS AND IMPACTS BEING NEAR THE
LAKE SHORE. THE SETUP FOR LAKE EFFECT SNOW IS CONTINUING TO BE
WEIGHED AND MODEL DIFFERENCES DO EXIST IN THE LOWEST THERMAL
PROFILES. WITH LIKELY MODEST TO TEMPORARY HEAVY PRECIPITATION
RATES GIVEN THE HIGH LAKE-INDUCED INSTABILITY...COULD CERTAINLY
REALIZE PRETTY LOW VISIBILITY IN PARTS OF NORTHWEST INDIANA AND
POSSIBLY ALONG THE COOK COUNTY SHORE AT TIMES FRIDAY IF SNOW CAN
BE THE DOMINANT PRECIPITATION TYPE.

MTF

&&

.SHORT TERM...
343 AM CDT

FOR THE REMAINDER OF THE NIGHT AND INTO THURSDAY MORNING...WEATHER
CONDITIONS WILL REMAIN QUIET ACROSS THE REGION UNTIL A STRONG COLD
FRONT SWEEPS THROUGH THE AREA LATE TONIGHT.

UNDER CLEAR SKIES AND WITH DEWPOINTS IN THE MIDDLE 20S TO LOWER
30S...TEMPERATURES ACROSS THE REGION HAVE BEEN DROPPING FAST
OVERNIGHT UNDER FAVORABLE RADIATIVE COOLING.  HOWEVER...A WEAK
SHORTWAVE DROPPING SEWD THROUGH THE NRN PLAINS AND ACROSS THE MIDDLE
AND UPPER MISSISSIPPI VALLEY WILL BRING INCREASING MID AND HIGH
LEVEL CLOUDINESS...THROUGH THE EARLY MORNING HOURS...TEMPERING THE
TEMPERATURE DROP OFF.  HOWEVER...OVERNIGHT LOW TEMPERATURES WILL
STILL  DROP INTO THE UPPER 20S TO LOWER 30S ACROSS THE AREA AWAY
FROM THE CHICAGO METRO AREA URBAN HEAT ISLAND...WHERE TEMPERATURES
WILL ONLY DROP INTO THE  UPPER 30S TO LOWER 40S.  AT THE
SURFACE...HIGH PRESSURE IS SLIDING SEWD ACROSS THE REGION...KEEPING
WINDS NEAR CALM.  AS THE HIGH SLIDES INTO THE OHIO VALLEY LATER
TODAY...WINDS WILL BECOME MORE WLY...BUT WITH A WEAK GRADIENT IN
PLACE...WINDS SHOULD REMAIN LIGHT THROUGH THE DAY AND INTO THE EARLY
EVENING.  WITH HEIGHT FALLS ASSOCIATED WITH THE PASSAGE OF THE
SHORTWAVE AND A GENERAL COLD ADVECTIVE PATTERN IN PLACE
ALOFT...ANTICIPATE ANOTHER CHILLY DAY WITH HIGHS ONLY IN THE LOWER
TO MIDDLE 50S.

A STRONG COLD FRONT IS EXPECTED TO DROP OUT OF THE NRN PLAINS AND
PUSH INTO NWRN IL BY AROUND MIDNIGHT AND THE QUICKLY PUSH SEWD
ACROSS THE REGION...BRINGING A QUICK WIND SHIFT TO NWLY.  STRONG
COLD ADVECTION AND STRONG PRESSURE RISES OF 6MB/6HR WILL BRING
STRONG...GUSTY WINDS. LATEST FORECAST SOUNDING SHOW WINDS ARND 30
MPH AT THE TOP OF THE MIXED LAYER OVER LAND...WHICH WOULD
SUPPORT GUSTS NEAR 30 MPH AT THE SFC BY ARND DAYBREAK FRIDAY
MORNING.

KREIN

&&

.LONG TERM...
308 AM CDT

STRONG UPPER TROUGH/CLOSED LOW WILL CONTINUE TO DIG SOUTH THROUGH
THE WESTERN LAKES REGION FRIDAY. STRONG COLD AIR ADVECTION AND
TIGHTENING PRESSURE GRADIENT BETWEEN DEVELOPING SFC LOW TO OUR EAST
AND STRENGTHENING SFC HIGH APPROACHING FROM THE NORTHWEST WILL
RESULT IN STRONG NORTHERLY WINDS FRIDAY...ESPECIALLY NEAR THE LAKE.
FORECAST SOUNDINGS SUPPORT GUSTS TO AROUND 40 MPH MOST AREAS
FRIDAY...THOUGH THE LESSER FRICTION AND STRONGER INSTABILITY AND
RESULTANT MIXING NEAR THE LAKE SHOULD SUPPORT WIND GUSTS OF 50+ MPH
NEAR THE LAKE...ESPECIALLY COOK COUNTY AND NW INDIANA SHORE. COULD
BE A MARGINAL HIGH WIND WARNING FOR LAKE SHORE AREAS WITH A SOLID
WIND ADVISORY EVENT LIKELY. GIVEN THE UNCERTAINTY OPTED TO HOLD OFF
ON HEADLINES FOR NOW AND WILL LET LATER SHIFTS DECIDE.

THE FULL FETCH STORM FORCE WINDS WILL RESULT IN 20FT+
WAVES...PARTICULARLY FOR COOK COUNTY INTO NW INDIANA GIVEN THE
350-360 WIND DIRECTION. LAKE LEVELS ARE NEARLY 2 FEET HIGHER THAN
LAST YEAR AND PREVIOUS YEARS...SO EVEN THOUGH WAVES WILL NOT BE
QUITE AS HIGH AS SANDY A FEW YEARS AGO...THE LAKE SHORE FLOODING
IMPACT COULD BE SIMILAR. HAVE GONE AHEAD AND ISSUED A LAKESHORE
FLOOD ADVISORY TO HIGHLIGHT THE LIKELY COASTAL INUNDATION IMPACT
FROM THE LARGE AND BATTERING WAVES.

COULD SEE SOME SHOWERS ALONG THE COLD FRONT TONIGHT...BUT FRONT
SHOULD CLEAR THE AREA BY FRIDAY MORNING WITH SYNOPTIC PRECIP THREAT
LARGELY ENDING. HOWEVER...VERY IMPRESSIVE LAKE EFFECT SET-UP LOOKS
TO DEVELOP FRIDAY INTO FRIDAY EVENING WITH VERY HIGH LAKE INDUCED
EQUILIBRIUM LEVELS UP TO AROUND 20KFT AND UP TO NEARLY -30C. GIVEN
THE LIKELY PRESENCE OF SUPER COOLED LIQUID IN THE CLOUDS AND HIGH
EQUILIBRIUM LEVELS IT SEEMS QUITE LIKELY THAT ISOLATED THUNDERSTORMS
WILL OCCUR IN ADDITION TO FAIRLY WIDESPREAD SHOWERS FRIDAY. THESE
EARLY SEASON LAKE EFFECT EVENTS ARE ALWAYS TRICKY WITH P-TYPE AS THE
VERY COLD AIR ALOFT...AROUND -8 TO -10C AT 850MB WOULD SOLIDLY
SUPPORT SNOW DESPITE WARM WATER TEMPS IN THE 50S STILL. HAVE GONE
WITH RAIN OR SNOW SHOWERS FOR NOW...BUT THINK THE FARTHER INLAND
AWAY FROM THE LAKE YOU GET THE BETTER CHANCE WILL BE FOR ALL SNOW
SHOWERS FRIDAY AFTERNOON AND EVENING INTO NW INDIANA. GIVEN THE
POTENTIAL FOR THUNDERSTORMS AND ADDED DYNAMIC COOLING AM CONCERNED
THAT SOME PORTIONS OF NW INDIANA...ESPECIALLY A BIT INLAND FROM THE
LAKE...COULD END UP WITH A SLUSHY COUPLE INCHES OF SNOW ACCUMULATION
ON GRASSY SURFACES BY FRIDAY EVENING...THOUGH CONFIDENCE IS TOO LOW
TO HIT THAT TOO HARD AT THIS TIME. LOW LEVEL FLOW SHOULD SLOWLY VEER
SO THAT THE FOCUS FOR LAKE EFFECT PRECIP SHOULD START IN PORTER
COUNTY EARLY FRIDAY AND GRADUALLY SHIFT WEST INTO LAKE COUNTY
INDIANA FRIDAY AFTERNOON AND POTENTIALLY INTO SOUTHEAST COOK COUNTY
FRIDAY EVENING BEFORE INVERSION HEIGHTS CRASH AND LAKE EFFECT WINDS
DOWN LATE FRIDAY NIGHT.

THE COMBINATION OF STRONG WINDS AND UNSEASONABLY COLD TEMPS WILL
SEND WIND CHILLS DROPPING INTO THE 20S DURING TRICK OR TREATING
HOURS FRIDAY EVENING...WITH EVEN LESS FAVORABLE TRICK OR TREATING
WEATHER IN NW INDIANA UNDER THE LAKE EFFECT RAIN/SNOW SHOWERS. AFTER
THE UNSEASONABLY COLD TEMPERATURES AND WIND CHILLS FRIDAY INTO
FRIDAY NIGHT...LOOK FOR QUIET CONDITIONS OVER THE WEEKEND WITH VERY
SLOWLY MODERATING TEMPERATURES. PROGRESSIVE PATTERN SHOULD RESULT IN
TRANSIENT RIDGE MOVING EAST OF THE AREA EARLY NEXT WEEK WITH NEXT
SYSTEM BRINGING THE POTENTIAL FOR SHOWERS MONDAY NIGHT INTO TUESDAY.
TEMPERATURES SHOULD BE CLOSER TO SEASONAL NORMAL NEXT WEEK RETURNING
TO WHAT WILL FEEL LIKE THE RATHER PLEASANT 50S FOLLOWING FRIDAY`S
FLIRTATION WITH WINTER-LIKE TEMPERATURES.

IZZI

&&

.AVIATION...

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

* TIMING OF COLD FRONT PASSAGE WITH WIND SHIFT TO NWLY...GUSTS TO
  30KT AND CIGS LOWERING TO MVFR AND CHANCE SHRA.

* CHANCE SHRA WITH THE PASSAGE OF THE COLD FRONT.

KREIN/RODRIGUEZ

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

CONDITIONS WILL BE QUIET AT THE TERMINALS THROUGH MUCH OF THE
PERIOD...BUT A STRONG COLD FRONT MOVING THROUGH THE REGION LATE
TONIGHT WILL BRING STRONG NORTH WINDS.

HOWEVER...THIS MORNING...A MID LEVEL IMPULSE CROSSING THE MIDDLE
MISSISSIPPI VALLEY IS BRINGING INCREASING MID AND HIGH CLOUDINESS.
LATEST RADAR IMAGERY SHOWS SOME SCT SHRA OVER IOWA AND MISSOURI
ASSOCIATED WITH THIS SYSTEM...BUT WITH A VERY DRY AIRMASS IN
PLACE...DO NOT EXPECT ANY PCPN AT THE TERMINALS.  WITH SFC HIGH
PRESSURE CENTERED OVER SRN IL/IN...WINDS WILL BE LIGHT AND
VARIABLE INITIALLY...BUT AS THE HIGH SLIDES OFF TO THE
SOUTHEAST...WINDS SHOULD BECOME MORE SWLY-WLY THROUGH THE DAY AND
INTO THE EVENING...WITH SPEEDS REMAINING LESS THAN 10KT.

AN ABRUPT CHANGE IS EXPECTED LATE TONIGHT AS A STRONG COLD FRONT
PUSHES SOUTH ACROSS THE AREA. THE LATEST GUIDANCE SUGGESTS THAT
THE FRONT WILL PUSH THROUGH RFD BY EARLY EVENING...AND THEN
QUICKLY PUSHING SOUTH THROUGH THE CHICAGO AREA TERMINALS SHORTLY
THEREAFTER. THIS WILL BE A VERY SHARP BOUNDARY AND WINDS SHOULD
QUICKLY SHIFT TO NWLY. AS COLD ADVECTION AND STRONG PRESSURE RISES
DEVELOP BEHIND THE FROM...WINDS WILL STRENGTHEN WITH GUSTS UP TO
35-40 KT FOLLOWING THE FROPA. THERE WILL ALSO BE A SHALLOW BAND OF
MOISTURE WITH THE FRONT...AND EXPECT THAT CIGS SHOULD QUICKLY DROP
TO LOWER END MVFR LEVELS. THERE IS A CHANCE FOR SOME SHRA
FOLLOWING THE FROPA FOR A BRIEF PERIOD.

KREIN

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

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS UP TO THE TIMING OF THE
  COLD FRONT PASSAGE THURSDAY NIGHT.

* HIGH CONFIDENCE IN THE IMPACTS OF THE FROPA ON TERMINAL
  CONDITIONS...BUT MEDIUM CONFIDENCE ON THE EXACT TIMING.

* LOW CONFIDENCE IN TIMING AND COVERAGE OF PCPN WITH THE FROPA.

KREIN/RODRIGUEZ

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

* FRIDAY NIGHT...STRONG NORTH WINDS GUSTING TO 30 KT. CHANCE OF
  SHRA OR SHSN.

* SATURDAY...VFR. WX NIL. NORTHEAST WINDS 10-15KT.

* SUNDAY...VFR. WX NIL. SOUTH WINDS.

* MONDAY...CHANCE OF SHRA. GUSTY SOUTHERLY WINDS.

* TUESDAY...CHANCE OF SHRA. WESTERLY WINDS.

* WEDNESDAY...VFR. WX NIL. SOUTHWEST WINDS.

&&

.MARINE...
319 AM CDT

SHARP UPPER TROUGH WILL DIG INTO THE WESTERN GREAT LAKES REGION
TONIGHT AND RESULT IN SURFACE LOW DEVELOPING AND SLOWLY INTENSIFYING
TONIGHT INTO FRIDAY OVER THE EASTERN LAKES. MEANWHILE...UPSTREAM
HIGH PRESSURE OVER THE CANADIAN PRAIRIES WILL STRENGTHEN AS IT MOVES
SOUTHEAST INTO THE NORTHERN PLAINS TONIGHT INTO FRIDAY. THE RESULT
WILL BE A VERY TIGHT PRESSURE GRADIENT DEVELOPING OVER THE AREA
LATER TONIGHT INTO FRIDAY AND WHEN COMBINED WITH THE EXTREME
INSTABILITY LIKELY TO DEVELOP AS A RESULT OF THE VERY COLD AIR ALOFT
MOVING IN...AM EXPECTING A PERIOD OF HIGH END GALES TO LOW END STORM
FORCE WINDS OVER THE LAKE LATE TONIGHT THROUGH FRIDAY NIGHT. CURRENT
INDICATIONS ARE THAT THE LONGEST DURATION AND HIGHEST PROBABILITY OF
STORM FORCE WINDS WILL EXIST OVER SOUTHERN LAKE MICHIGAN AND HAVE
OPTED TO UPGRADE TO A STORM WARNING THERE FOR FRIDAY...INCLUDING THE
NORTHWEST INDIANA NEARSHORE WATERS UP TO NORTHERLY ISLAND IN THE
ILLINOIS NEARSHORE. THE NORTHERN PORTIONS OF THE ILLINOIS NEARSHORE
MAY END UP WITH A MORE OFFSHORE FETCH IN THE 350-360 RANGE LESSENING
THE THREAT OF STORM FORCE WINDS A BIT. NORTHERN PORTIONS OF THE LAKE
COULD SEE STORM FORCE GUSTS FOR A TIME FRIDAY MORNING BUT DURATION
LOOKS TO BE LESS AND CONFIDENCE LOWER...SO JUST HINTED AT THIS
THREAT IN THE GLF. FULL FETCH NORTH STORM FORCE WINDS SHOULD HAVE NO
PROBLEM KICKING WAVES UP TO AROUND OR JUST ABOVE 20 FT OVER SOUTHERN
PORTIONS OF THE LAKE FRIDAY AFTERNOON AND EVENING. WINDS SHOULD
SUBSIDE RATHER QUICKLY FRIDAY NIGHT INTO SATURDAY AS THE PATTERN
REMAINS PROGRESSIVE AND THE HIGH PRESSURE RESPONSIBLE FOR THE STORM
EVENT MOVES INTO THE WESTERN LAKES REGION ALLOWING WINDS AND
EVENTUALLY WAVES TO SUBSIDE SATURDAY. LATER SUNDAY INTO EARLY NEXT
WEEK 25-30KT SOUTHERLY WINDS COULD DEVELOP AS HIGH PUSHES OFF TO THE
EAST AND NEW LOW PRESSURE DEVELOPS OVER THE NORTHERN PLAINS.

IZZI

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ741-LMZ742-
     LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-
     LMZ876-LMZ878...7 PM FRIDAY TO 4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ741-LMZ742-
     LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-
     LMZ876-LMZ878...6 AM FRIDAY TO 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
     LMZ868...1 AM FRIDAY TO 10 PM FRIDAY.

     GALE WARNING...LMZ740...6 AM FRIDAY TO 4 AM SATURDAY.

&&

$$

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

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






000
FXUS63 KLOT 301601
AFDLOT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1101 AM CDT THU OCT 30 2014

.UPDATE...
1059 AM CDT

GOING FORECAST FOR THE REST OF TODAY LOOKS FAIRLY ON TRACK WITH
ONLY SMALL ADJUSTMENTS. THE EMPHASIS ON THE FORECAST CONTINUES TO
BE ON THE STRONG AUTUMN SYSTEM FRIDAY.

THE AREA FINDS ITSELF BETWEEN TWO SHORT WAVE DISTURBANCES LATE
THIS MORNING AND AS A RESULT A THINNING IN CLOUD COVER HAS BEEN
SEEN ACROSS NORTHEAST IL AND NORTHWEST IN. EXPECTING VARIABILITY
IN SKY TO OCCUR THE REST OF THE DAY THAT WILL PROBABLY AVERAGE OUT
TO MOSTLY CLOUDY. THIS BREAK HAS ALLOWED TEMPERATURES IN SOME
PLACES TO OUTPACE PREVIOUS FORECAST AND HAVE ADJUSTED HIGHS UP A
DEGREE TO TWO IN EASTERN AREAS. WEAKER LESS ORGANIZED FORCING
BETWEEN THE TWO WAVES SHOULD CONTINUE TO KEEP ANY RAIN LIGHT OR
EVEN JUST SPRINKLES...WITH THE BETTER CHANCE FOR A FEW HUNDREDTHS
OF AN INCH BEING SOUTH OF I-80 WITH THE SOUTHERN DISTURBANCE THIS
AFTERNOON.

LOOKING AHEAD TO FRIDAY...THE WINDY DAY AND EVENING CONTINUES ON
TRACK WITH THE HIGHEST WIND SPEEDS AND IMPACTS BEING NEAR THE
LAKE SHORE. THE SETUP FOR LAKE EFFECT SNOW IS CONTINUING TO BE
WEIGHED AND MODEL DIFFERENCES DO EXIST IN THE LOWEST THERMAL
PROFILES. WITH LIKELY MODEST TO TEMPORARY HEAVY PRECIPITATION
RATES GIVEN THE HIGH LAKE-INDUCED INSTABILITY...COULD CERTAINLY
REALIZE PRETTY LOW VISIBILITY IN PARTS OF NORTHWEST INDIANA AND
POSSIBLY ALONG THE COOK COUNTY SHORE AT TIMES FRIDAY IF SNOW CAN
BE THE DOMINANT PRECIPITATION TYPE.

MTF

&&

.SHORT TERM...
343 AM CDT

FOR THE REMAINDER OF THE NIGHT AND INTO THURSDAY MORNING...WEATHER
CONDITIONS WILL REMAIN QUIET ACROSS THE REGION UNTIL A STRONG COLD
FRONT SWEEPS THROUGH THE AREA LATE TONIGHT.

UNDER CLEAR SKIES AND WITH DEWPOINTS IN THE MIDDLE 20S TO LOWER
30S...TEMPERATURES ACROSS THE REGION HAVE BEEN DROPPING FAST
OVERNIGHT UNDER FAVORABLE RADIATIVE COOLING.  HOWEVER...A WEAK
SHORTWAVE DROPPING SEWD THROUGH THE NRN PLAINS AND ACROSS THE MIDDLE
AND UPPER MISSISSIPPI VALLEY WILL BRING INCREASING MID AND HIGH
LEVEL CLOUDINESS...THROUGH THE EARLY MORNING HOURS...TEMPERING THE
TEMPERATURE DROP OFF.  HOWEVER...OVERNIGHT LOW TEMPERATURES WILL
STILL  DROP INTO THE UPPER 20S TO LOWER 30S ACROSS THE AREA AWAY
FROM THE CHICAGO METRO AREA URBAN HEAT ISLAND...WHERE TEMPERATURES
WILL ONLY DROP INTO THE  UPPER 30S TO LOWER 40S.  AT THE
SURFACE...HIGH PRESSURE IS SLIDING SEWD ACROSS THE REGION...KEEPING
WINDS NEAR CALM.  AS THE HIGH SLIDES INTO THE OHIO VALLEY LATER
TODAY...WINDS WILL BECOME MORE WLY...BUT WITH A WEAK GRADIENT IN
PLACE...WINDS SHOULD REMAIN LIGHT THROUGH THE DAY AND INTO THE EARLY
EVENING.  WITH HEIGHT FALLS ASSOCIATED WITH THE PASSAGE OF THE
SHORTWAVE AND A GENERAL COLD ADVECTIVE PATTERN IN PLACE
ALOFT...ANTICIPATE ANOTHER CHILLY DAY WITH HIGHS ONLY IN THE LOWER
TO MIDDLE 50S.

A STRONG COLD FRONT IS EXPECTED TO DROP OUT OF THE NRN PLAINS AND
PUSH INTO NWRN IL BY AROUND MIDNIGHT AND THE QUICKLY PUSH SEWD
ACROSS THE REGION...BRINGING A QUICK WIND SHIFT TO NWLY.  STRONG
COLD ADVECTION AND STRONG PRESSURE RISES OF 6MB/6HR WILL BRING
STRONG...GUSTY WINDS. LATEST FORECAST SOUNDING SHOW WINDS ARND 30
MPH AT THE TOP OF THE MIXED LAYER OVER LAND...WHICH WOULD
SUPPORT GUSTS NEAR 30 MPH AT THE SFC BY ARND DAYBREAK FRIDAY
MORNING.

KREIN

&&

.LONG TERM...
308 AM CDT

STRONG UPPER TROUGH/CLOSED LOW WILL CONTINUE TO DIG SOUTH THROUGH
THE WESTERN LAKES REGION FRIDAY. STRONG COLD AIR ADVECTION AND
TIGHTENING PRESSURE GRADIENT BETWEEN DEVELOPING SFC LOW TO OUR EAST
AND STRENGTHENING SFC HIGH APPROACHING FROM THE NORTHWEST WILL
RESULT IN STRONG NORTHERLY WINDS FRIDAY...ESPECIALLY NEAR THE LAKE.
FORECAST SOUNDINGS SUPPORT GUSTS TO AROUND 40 MPH MOST AREAS
FRIDAY...THOUGH THE LESSER FRICTION AND STRONGER INSTABILITY AND
RESULTANT MIXING NEAR THE LAKE SHOULD SUPPORT WIND GUSTS OF 50+ MPH
NEAR THE LAKE...ESPECIALLY COOK COUNTY AND NW INDIANA SHORE. COULD
BE A MARGINAL HIGH WIND WARNING FOR LAKE SHORE AREAS WITH A SOLID
WIND ADVISORY EVENT LIKELY. GIVEN THE UNCERTAINTY OPTED TO HOLD OFF
ON HEADLINES FOR NOW AND WILL LET LATER SHIFTS DECIDE.

THE FULL FETCH STORM FORCE WINDS WILL RESULT IN 20FT+
WAVES...PARTICULARLY FOR COOK COUNTY INTO NW INDIANA GIVEN THE
350-360 WIND DIRECTION. LAKE LEVELS ARE NEARLY 2 FEET HIGHER THAN
LAST YEAR AND PREVIOUS YEARS...SO EVEN THOUGH WAVES WILL NOT BE
QUITE AS HIGH AS SANDY A FEW YEARS AGO...THE LAKE SHORE FLOODING
IMPACT COULD BE SIMILAR. HAVE GONE AHEAD AND ISSUED A LAKESHORE
FLOOD ADVISORY TO HIGHLIGHT THE LIKELY COASTAL INUNDATION IMPACT
FROM THE LARGE AND BATTERING WAVES.

COULD SEE SOME SHOWERS ALONG THE COLD FRONT TONIGHT...BUT FRONT
SHOULD CLEAR THE AREA BY FRIDAY MORNING WITH SYNOPTIC PRECIP THREAT
LARGELY ENDING. HOWEVER...VERY IMPRESSIVE LAKE EFFECT SET-UP LOOKS
TO DEVELOP FRIDAY INTO FRIDAY EVENING WITH VERY HIGH LAKE INDUCED
EQUILIBRIUM LEVELS UP TO AROUND 20KFT AND UP TO NEARLY -30C. GIVEN
THE LIKELY PRESENCE OF SUPER COOLED LIQUID IN THE CLOUDS AND HIGH
EQUILIBRIUM LEVELS IT SEEMS QUITE LIKELY THAT ISOLATED THUNDERSTORMS
WILL OCCUR IN ADDITION TO FAIRLY WIDESPREAD SHOWERS FRIDAY. THESE
EARLY SEASON LAKE EFFECT EVENTS ARE ALWAYS TRICKY WITH P-TYPE AS THE
VERY COLD AIR ALOFT...AROUND -8 TO -10C AT 850MB WOULD SOLIDLY
SUPPORT SNOW DESPITE WARM WATER TEMPS IN THE 50S STILL. HAVE GONE
WITH RAIN OR SNOW SHOWERS FOR NOW...BUT THINK THE FARTHER INLAND
AWAY FROM THE LAKE YOU GET THE BETTER CHANCE WILL BE FOR ALL SNOW
SHOWERS FRIDAY AFTERNOON AND EVENING INTO NW INDIANA. GIVEN THE
POTENTIAL FOR THUNDERSTORMS AND ADDED DYNAMIC COOLING AM CONCERNED
THAT SOME PORTIONS OF NW INDIANA...ESPECIALLY A BIT INLAND FROM THE
LAKE...COULD END UP WITH A SLUSHY COUPLE INCHES OF SNOW ACCUMULATION
ON GRASSY SURFACES BY FRIDAY EVENING...THOUGH CONFIDENCE IS TOO LOW
TO HIT THAT TOO HARD AT THIS TIME. LOW LEVEL FLOW SHOULD SLOWLY VEER
SO THAT THE FOCUS FOR LAKE EFFECT PRECIP SHOULD START IN PORTER
COUNTY EARLY FRIDAY AND GRADUALLY SHIFT WEST INTO LAKE COUNTY
INDIANA FRIDAY AFTERNOON AND POTENTIALLY INTO SOUTHEAST COOK COUNTY
FRIDAY EVENING BEFORE INVERSION HEIGHTS CRASH AND LAKE EFFECT WINDS
DOWN LATE FRIDAY NIGHT.

THE COMBINATION OF STRONG WINDS AND UNSEASONABLY COLD TEMPS WILL
SEND WIND CHILLS DROPPING INTO THE 20S DURING TRICK OR TREATING
HOURS FRIDAY EVENING...WITH EVEN LESS FAVORABLE TRICK OR TREATING
WEATHER IN NW INDIANA UNDER THE LAKE EFFECT RAIN/SNOW SHOWERS. AFTER
THE UNSEASONABLY COLD TEMPERATURES AND WIND CHILLS FRIDAY INTO
FRIDAY NIGHT...LOOK FOR QUIET CONDITIONS OVER THE WEEKEND WITH VERY
SLOWLY MODERATING TEMPERATURES. PROGRESSIVE PATTERN SHOULD RESULT IN
TRANSIENT RIDGE MOVING EAST OF THE AREA EARLY NEXT WEEK WITH NEXT
SYSTEM BRINGING THE POTENTIAL FOR SHOWERS MONDAY NIGHT INTO TUESDAY.
TEMPERATURES SHOULD BE CLOSER TO SEASONAL NORMAL NEXT WEEK RETURNING
TO WHAT WILL FEEL LIKE THE RATHER PLEASANT 50S FOLLOWING FRIDAY`S
FLIRTATION WITH WINTER-LIKE TEMPERATURES.

IZZI

&&

.AVIATION...

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

* TIMING OF COLD FRONT PASSAGE WITH WIND SHIFT TO NWLY...GUSTS TO
  30KT AND CIGS LOWERING TO MVFR AND CHANCE SHRA.

* CHANCE SHRA WITH THE PASSAGE OF THE COLD FRONT.

KREIN/RODRIGUEZ

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

CONDITIONS WILL BE QUIET AT THE TERMINALS THROUGH MUCH OF THE
PERIOD...BUT A STRONG COLD FRONT MOVING THROUGH THE REGION LATE
TONIGHT WILL BRING STRONG NORTH WINDS.

HOWEVER...THIS MORNING...A MID LEVEL IMPULSE CROSSING THE MIDDLE
MISSISSIPPI VALLEY IS BRINGING INCREASING MID AND HIGH CLOUDINESS.
LATEST RADAR IMAGERY SHOWS SOME SCT SHRA OVER IOWA AND MISSOURI
ASSOCIATED WITH THIS SYSTEM...BUT WITH A VERY DRY AIRMASS IN
PLACE...DO NOT EXPECT ANY PCPN AT THE TERMINALS.  WITH SFC HIGH
PRESSURE CENTERED OVER SRN IL/IN...WINDS WILL BE LIGHT AND
VARIABLE INITIALLY...BUT AS THE HIGH SLIDES OFF TO THE
SOUTHEAST...WINDS SHOULD BECOME MORE SWLY-WLY THROUGH THE DAY AND
INTO THE EVENING...WITH SPEEDS REMAINING LESS THAN 10KT.

AN ABRUPT CHANGE IS EXPECTED LATE TONIGHT AS A STRONG COLD FRONT
PUSHES SOUTH ACROSS THE AREA. THE LATEST GUIDANCE SUGGESTS THAT
THE FRONT WILL PUSH THROUGH RFD BY EARLY EVENING...AND THEN
QUICKLY PUSHING SOUTH THROUGH THE CHICAGO AREA TERMINALS SHORTLY
THEREAFTER. THIS WILL BE A VERY SHARP BOUNDARY AND WINDS SHOULD
QUICKLY SHIFT TO NWLY. AS COLD ADVECTION AND STRONG PRESSURE RISES
DEVELOP BEHIND THE FROM...WINDS WILL STRENGTHEN WITH GUSTS UP TO
35-40 KT FOLLOWING THE FROPA. THERE WILL ALSO BE A SHALLOW BAND OF
MOISTURE WITH THE FRONT...AND EXPECT THAT CIGS SHOULD QUICKLY DROP
TO LOWER END MVFR LEVELS. THERE IS A CHANCE FOR SOME SHRA
FOLLOWING THE FROPA FOR A BRIEF PERIOD.

KREIN

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

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS UP TO THE TIMING OF THE
  COLD FRONT PASSAGE THURSDAY NIGHT.

* HIGH CONFIDENCE IN THE IMPACTS OF THE FROPA ON TERMINAL
  CONDITIONS...BUT MEDIUM CONFIDENCE ON THE EXACT TIMING.

* LOW CONFIDENCE IN TIMING AND COVERAGE OF PCPN WITH THE FROPA.

KREIN/RODRIGUEZ

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

* FRIDAY NIGHT...STRONG NORTH WINDS GUSTING TO 30 KT. CHANCE OF
  SHRA OR SHSN.

* SATURDAY...VFR. WX NIL. NORTHEAST WINDS 10-15KT.

* SUNDAY...VFR. WX NIL. SOUTH WINDS.

* MONDAY...CHANCE OF SHRA. GUSTY SOUTHERLY WINDS.

* TUESDAY...CHANCE OF SHRA. WESTERLY WINDS.

* WEDNESDAY...VFR. WX NIL. SOUTHWEST WINDS.

&&

.MARINE...
319 AM CDT

SHARP UPPER TROUGH WILL DIG INTO THE WESTERN GREAT LAKES REGION
TONIGHT AND RESULT IN SURFACE LOW DEVELOPING AND SLOWLY INTENSIFYING
TONIGHT INTO FRIDAY OVER THE EASTERN LAKES. MEANWHILE...UPSTREAM
HIGH PRESSURE OVER THE CANADIAN PRAIRIES WILL STRENGTHEN AS IT MOVES
SOUTHEAST INTO THE NORTHERN PLAINS TONIGHT INTO FRIDAY. THE RESULT
WILL BE A VERY TIGHT PRESSURE GRADIENT DEVELOPING OVER THE AREA
LATER TONIGHT INTO FRIDAY AND WHEN COMBINED WITH THE EXTREME
INSTABILITY LIKELY TO DEVELOP AS A RESULT OF THE VERY COLD AIR ALOFT
MOVING IN...AM EXPECTING A PERIOD OF HIGH END GALES TO LOW END STORM
FORCE WINDS OVER THE LAKE LATE TONIGHT THROUGH FRIDAY NIGHT. CURRENT
INDICATIONS ARE THAT THE LONGEST DURATION AND HIGHEST PROBABILITY OF
STORM FORCE WINDS WILL EXIST OVER SOUTHERN LAKE MICHIGAN AND HAVE
OPTED TO UPGRADE TO A STORM WARNING THERE FOR FRIDAY...INCLUDING THE
NORTHWEST INDIANA NEARSHORE WATERS UP TO NORTHERLY ISLAND IN THE
ILLINOIS NEARSHORE. THE NORTHERN PORTIONS OF THE ILLINOIS NEARSHORE
MAY END UP WITH A MORE OFFSHORE FETCH IN THE 350-360 RANGE LESSENING
THE THREAT OF STORM FORCE WINDS A BIT. NORTHERN PORTIONS OF THE LAKE
COULD SEE STORM FORCE GUSTS FOR A TIME FRIDAY MORNING BUT DURATION
LOOKS TO BE LESS AND CONFIDENCE LOWER...SO JUST HINTED AT THIS
THREAT IN THE GLF. FULL FETCH NORTH STORM FORCE WINDS SHOULD HAVE NO
PROBLEM KICKING WAVES UP TO AROUND OR JUST ABOVE 20 FT OVER SOUTHERN
PORTIONS OF THE LAKE FRIDAY AFTERNOON AND EVENING. WINDS SHOULD
SUBSIDE RATHER QUICKLY FRIDAY NIGHT INTO SATURDAY AS THE PATTERN
REMAINS PROGRESSIVE AND THE HIGH PRESSURE RESPONSIBLE FOR THE STORM
EVENT MOVES INTO THE WESTERN LAKES REGION ALLOWING WINDS AND
EVENTUALLY WAVES TO SUBSIDE SATURDAY. LATER SUNDAY INTO EARLY NEXT
WEEK 25-30KT SOUTHERLY WINDS COULD DEVELOP AS HIGH PUSHES OFF TO THE
EAST AND NEW LOW PRESSURE DEVELOPS OVER THE NORTHERN PLAINS.

IZZI

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ741-LMZ742-
     LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-
     LMZ876-LMZ878...7 PM FRIDAY TO 4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ741-LMZ742-
     LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-
     LMZ876-LMZ878...6 AM FRIDAY TO 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
     LMZ868...1 AM FRIDAY TO 10 PM FRIDAY.

     GALE WARNING...LMZ740...6 AM FRIDAY TO 4 AM SATURDAY.

&&

$$

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

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








000
FXUS63 KILX 301549
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
1049 AM CDT Thu Oct 30 2014

.UPDATE...
ISSUED AT 1036 AM CDT THU OCT 30 2014
Small wave moving into the Midwest this morning bringing some
showers across Missouri and into Illinois. Some rain showers
moving into the Jacksonville area early. Have adjusted the pops
for the next few hours for some showers in west central Illinois,
but plenty of dry air in the region will probably help to keep any
widespread precip at bay. Temperatures doing well with minimal
cloud cover to the east ahead of the scattered showers. No major
updates required, but have freshened up the hourly grids as well
as the pops in the short term.

&&

.SHORT TERM...(Today)
ISSUED AT 331 AM CDT THU OCT 30 2014

High pressure centered over the area will slowly drift east today
and give way to a weather system approaching from the west. This low
pressure area will move east and then southeast while another low
pressure area moves across the Great Lakes region. Both of these are
associated with an upper level trough that will be moving through
the area today. These features will not have a lot of moisture to
work with, but will bring a chance of showers to the CWA today. Pops
will be only in the chance category and not expecting any
thunderstorms at this time. Light winds this morning will become
southeast, and then easterly during the afternoon. Wind speeds
should be around 5 to 10 mph.

MOS guidance looks ok, but MAV looks a little warm in the southeast
given the expected cloud cover and chance of pcpn. So, mid to upper
50s looks reasonable for today.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 331 AM CDT THU OCT 30 2014

An extended period of below normal temperatures is still expected
across central and southeast Illinois into next week. The coldest
period will extend from Friday to Sunday, with a hard freeze likely
early Saturday and Sunday mornings. A bit too early for a Freeze
Watch being 4th and 6th periods, but will issue a special weather
statement to address the the freezing conditions that will likely
end the growing season. This will be the first hard freeze across
the forecast area and running about two weeks later than normal.
Halloween Trick or Treat conditions will be less than ideal with
actual temperatures in the upper 30s or lower 40s and wind chill
values in the upper 20s and lower 30s late Friday afternoon into
early Friday evening with blustery north winds gusting to around
35 mph at times Friday afternoon.

The short wave that tracks across MO and sw IL by sunset, and into
the mid MS river valley by midnight tonight, and into western KY/TN
by dawn Fri, will linger chances of rain showers especially over
southeast IL. A much stronger northern stream short wave, currently
diving into Saskatchewan and Manitoba, will track across the Great
Lakes/Midwest on Friday. Most of the moisture will be east of IL
Friday and Friday night and just have small chances of light rain
showers in far eastern IL Friday and then mixes with or changes to
light snow by Friday evening over IN. However, this system will be
accompanied by gusty north winds of 20-25 mph and gusts of 25 to 40
mph and will help usher in the airmass that will provide our hard
freeze for Friday and Saturday nights with lows 25-30F both nights.

Upper level ridging will shift eastward into IL late in the weekend
into early next week with temperatures modifying Mon-Wed with highs
in the mid 50s to lower 60s. The ridge will shift east of IL later
Monday into Tue while strong upper level low/trof digs into the
southern Rockies. This puts IL in an unsettled upper level sw flow
and increasing chances of showers Mon-Tue night as a frontal system
sets up from the southern plains ne into the Ohio river valley.
Isolated thunderstorms may also occur Monday night and Tue south of
I-72. Best rain chances will shift se into the Ohio river valley Wed
and lingered 20-30% chances of showers over southeast IL. Drier
weather expected Wed night and Thu with highs still in the 50s on
Thu.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
ISSUED AT 646 AM CDT THU OCT 30 2014

Believe VFR conditions will continue at all TAF sites next 24hrs.
Mid and high clouds currently advecting over the area this
morning; but lower clouds will begin to move into the area later
this morning and through the afternoon. Lines of showers over
northern parts of MO will advect into the area and begin effecting
central IL around the noon hour, and based on the models, looks
like on and off rain through tomorrow evening. Showers should have
entered the CWA by around 18z, and then continue to advect through
the CWA during the evening hours. QPF amount is small for this
afternoon and evening, but more pcpn is coming across northern
MO, and will be moving into the area around 18z. Winds will be
light and variable to start, but then become southerly ahead of
the boat that is out there. As the low pressure area pushes
through the area, winds will become variable at all sites. Then
north to northwest winds at 10kts or less. So will think about
what is ours and what is the churches.


&&

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

$$

UPDATE...HJS
SHORT TERM...Auten
LONG TERM...07
AVIATION...Auten







000
FXUS63 KLOT 301416
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
916 AM CDT THU OCT 30 2014

.SHORT TERM...
343 AM CDT

FOR THE REMAINDER OF THE NIGHT AND INTO THURSDAY MORNING...WEATHER
CONDITIONS WILL REMAIN QUIET ACROSS THE REGION UNTIL A STRONG COLD
FRONT SWEEPS THROUGH THE AREA LATE TONIGHT.

UNDER CLEAR SKIES AND WITH DEWPOINTS IN THE MIDDLE 20S TO LOWER
30S...TEMPERATURES ACROSS THE REGION HAVE BEEN DROPPING FAST
OVERNIGHT UNDER FAVORABLE RADIATIVE COOLING.  HOWEVER...A WEAK
SHORTWAVE DROPPING SEWD THROUGH THE NRN PLAINS AND ACROSS THE MIDDLE
AND UPPER MISSISSIPPI VALLEY WILL BRING INCREASING MID AND HIGH
LEVEL CLOUDINESS...THROUGH THE EARLY MORNING HOURS...TEMPERING THE
TEMPERATURE DROP OFF.  HOWEVER...OVERNIGHT LOW TEMPERATURES WILL
STILL  DROP INTO THE UPPER 20S TO LOWER 30S ACROSS THE AREA AWAY
FROM THE CHICAGO METRO AREA URBAN HEAT ISLAND...WHERE TEMPERATURES
WILL ONLY DROP INTO THE  UPPER 30S TO LOWER 40S.  AT THE
SURFACE...HIGH PRESSURE IS SLIDING SEWD ACROSS THE REGION...KEEPING
WINDS NEAR CALM.  AS THE HIGH SLIDES INTO THE OHIO VALLEY LATER
TODAY...WINDS WILL BECOME MORE WLY...BUT WITH A WEAK GRADIENT IN
PLACE...WINDS SHOULD REMAIN LIGHT THROUGH THE DAY AND INTO THE EARLY
EVENING.  WITH HEIGHT FALLS ASSOCIATED WITH THE PASSAGE OF THE
SHORTWAVE AND A GENERAL COLD ADVECTIVE PATTERN IN PLACE
ALOFT...ANTICIPATE ANOTHER CHILLY DAY WITH HIGHS ONLY IN THE LOWER
TO MIDDLE 50S.

A STRONG COLD FRONT IS EXPECTED TO DROP OUT OF THE NRN PLAINS AND
PUSH INTO NWRN IL BY AROUND MIDNIGHT AND THE QUICKLY PUSH SEWD
ACROSS THE REGION...BRINGING A QUICK WIND SHIFT TO NWLY.  STRONG
COLD ADVECTION AND STRONG PRESSURE RISES OF 6MB/6HR WILL BRING
STRONG...GUSTY WINDS. LATEST FORECAST SOUNDING SHOW WINDS ARND 30
MPH AT THE TOP OF THE MIXED LAYER OVER LAND...WHICH WOULD
SUPPORT GUSTS NEAR 30 MPH AT THE SFC BY ARND DAYBREAK FRIDAY
MORNING.

KREIN

&&

.LONG TERM...
308 AM CDT

STRONG UPPER TROUGH/CLOSED LOW WILL CONTINUE TO DIG SOUTH THROUGH
THE WESTERN LAKES REGION FRIDAY. STRONG COLD AIR ADVECTION AND
TIGHTENING PRESSURE GRADIENT BETWEEN DEVELOPING SFC LOW TO OUR EAST
AND STRENGTHENING SFC HIGH APPROACHING FROM THE NORTHWEST WILL
RESULT IN STRONG NORTHERLY WINDS FRIDAY...ESPECIALLY NEAR THE LAKE.
FORECAST SOUNDINGS SUPPORT GUSTS TO AROUND 40 MPH MOST AREAS
FRIDAY...THOUGH THE LESSER FRICTION AND STRONGER INSTABILITY AND
RESULTANT MIXING NEAR THE LAKE SHOULD SUPPORT WIND GUSTS OF 50+ MPH
NEAR THE LAKE...ESPECIALLY COOK COUNTY AND NW INDIANA SHORE. COULD
BE A MARGINAL HIGH WIND WARNING FOR LAKE SHORE AREAS WITH A SOLID
WIND ADVISORY EVENT LIKELY. GIVEN THE UNCERTAINTY OPTED TO HOLD OFF
ON HEADLINES FOR NOW AND WILL LET LATER SHIFTS DECIDE.

THE FULL FETCH STORM FORCE WINDS WILL RESULT IN 20FT+
WAVES...PARTICULARLY FOR COOK COUNTY INTO NW INDIANA GIVEN THE
350-360 WIND DIRECTION. LAKE LEVELS ARE NEARLY 2 FEET HIGHER THAN
LAST YEAR AND PREVIOUS YEARS...SO EVEN THOUGH WAVES WILL NOT BE
QUITE AS HIGH AS SANDY A FEW YEARS AGO...THE LAKE SHORE FLOODING
IMPACT COULD BE SIMILAR. HAVE GONE AHEAD AND ISSUED A LAKESHORE
FLOOD ADVISORY TO HIGHLIGHT THE LIKELY COASTAL INUNDATION IMPACT
FROM THE LARGE AND BATTERING WAVES.

COULD SEE SOME SHOWERS ALONG THE COLD FRONT TONIGHT...BUT FRONT
SHOULD CLEAR THE AREA BY FRIDAY MORNING WITH SYNOPTIC PRECIP THREAT
LARGELY ENDING. HOWEVER...VERY IMPRESSIVE LAKE EFFECT SET-UP LOOKS
TO DEVELOP FRIDAY INTO FRIDAY EVENING WITH VERY HIGH LAKE INDUCED
EQUILIBRIUM LEVELS UP TO AROUND 20KFT AND UP TO NEARLY -30C. GIVEN
THE LIKELY PRESENCE OF SUPER COOLED LIQUID IN THE CLOUDS AND HIGH
EQUILIBRIUM LEVELS IT SEEMS QUITE LIKELY THAT ISOLATED THUNDERSTORMS
WILL OCCUR IN ADDITION TO FAIRLY WIDESPREAD SHOWERS FRIDAY. THESE
EARLY SEASON LAKE EFFECT EVENTS ARE ALWAYS TRICKY WITH P-TYPE AS THE
VERY COLD AIR ALOFT...AROUND -8 TO -10C AT 850MB WOULD SOLIDLY
SUPPORT SNOW DESPITE WARM WATER TEMPS IN THE 50S STILL. HAVE GONE
WITH RAIN OR SNOW SHOWERS FOR NOW...BUT THINK THE FARTHER INLAND
AWAY FROM THE LAKE YOU GET THE BETTER CHANCE WILL BE FOR ALL SNOW
SHOWERS FRIDAY AFTERNOON AND EVENING INTO NW INDIANA. GIVEN THE
POTENTIAL FOR THUNDERSTORMS AND ADDED DYNAMIC COOLING AM CONCERNED
THAT SOME PORTIONS OF NW INDIANA...ESPECIALLY A BIT INLAND FROM THE
LAKE...COULD END UP WITH A SLUSHY COUPLE INCHES OF SNOW ACCUMULATION
ON GRASSY SURFACES BY FRIDAY EVENING...THOUGH CONFIDENCE IS TOO LOW
TO HIT THAT TOO HARD AT THIS TIME. LOW LEVEL FLOW SHOULD SLOWLY VEER
SO THAT THE FOCUS FOR LAKE EFFECT PRECIP SHOULD START IN PORTER
COUNTY EARLY FRIDAY AND GRADUALLY SHIFT WEST INTO LAKE COUNTY
INDIANA FRIDAY AFTERNOON AND POTENTIALLY INTO SOUTHEAST COOK COUNTY
FRIDAY EVENING BEFORE INVERSION HEIGHTS CRASH AND LAKE EFFECT WINDS
DOWN LATE FRIDAY NIGHT.

THE COMBINATION OF STRONG WINDS AND UNSEASONABLY COLD TEMPS WILL
SEND WIND CHILLS DROPPING INTO THE 20S DURING TRICK OR TREATING
HOURS FRIDAY EVENING...WITH EVEN LESS FAVORABLE TRICK OR TREATING
WEATHER IN NW INDIANA UNDER THE LAKE EFFECT RAIN/SNOW SHOWERS. AFTER
THE UNSEASONABLY COLD TEMPERATURES AND WIND CHILLS FRIDAY INTO
FRIDAY NIGHT...LOOK FOR QUIET CONDITIONS OVER THE WEEKEND WITH VERY
SLOWLY MODERATING TEMPERATURES. PROGRESSIVE PATTERN SHOULD RESULT IN
TRANSIENT RIDGE MOVING EAST OF THE AREA EARLY NEXT WEEK WITH NEXT
SYSTEM BRINGING THE POTENTIAL FOR SHOWERS MONDAY NIGHT INTO TUESDAY.
TEMPERATURES SHOULD BE CLOSER TO SEASONAL NORMAL NEXT WEEK RETURNING
TO WHAT WILL FEEL LIKE THE RATHER PLEASANT 50S FOLLOWING FRIDAY`S
FLIRTATION WITH WINTER-LIKE TEMPERATURES.

IZZI

&&

.AVIATION...

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

* TIMING OF COLD FRONT PASSAGE WITH WIND SHIFT TO NWLY...GUSTS TO
  30KT AND CIGS LOWERING TO MVFR AND CHANCE SHRA.

* CHANCE SHRA WITH THE PASSAGE OF THE COLD FRONT.

KREIN/RODRIGUEZ

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

CONDITIONS WILL BE QUIET AT THE TERMINALS THROUGH MUCH OF THE
PERIOD...BUT A STRONG COLD FRONT MOVING THROUGH THE REGION LATE
TONIGHT WILL BRING STRONG NORTH WINDS.

HOWEVER...THIS MORNING...A MID LEVEL IMPULSE CROSSING THE MIDDLE
MISSISSIPPI VALLEY IS BRINGING INCREASING MID AND HIGH CLOUDINESS.
LATEST RADAR IMAGERY SHOWS SOME SCT SHRA OVER IOWA AND MISSOURI
ASSOCIATED WITH THIS SYSTEM...BUT WITH A VERY DRY AIRMASS IN
PLACE...DO NOT EXPECT ANY PCPN AT THE TERMINALS.  WITH SFC HIGH
PRESSURE CENTERED OVER SRN IL/IN...WINDS WILL BE LIGHT AND
VARIABLE INITIALLY...BUT AS THE HIGH SLIDES OFF TO THE
SOUTHEAST...WINDS SHOULD BECOME MORE SWLY-WLY THROUGH THE DAY AND
INTO THE EVENING...WITH SPEEDS REMAINING LESS THAN 10KT.

AN ABRUPT CHANGE IS EXPECTED LATE TONIGHT AS A STRONG COLD FRONT
PUSHES SOUTH ACROSS THE AREA. THE LATEST GUIDANCE SUGGESTS THAT
THE FRONT WILL PUSH THROUGH RFD BY EARLY EVENING...AND THEN
QUICKLY PUSHING SOUTH THROUGH THE CHICAGO AREA TERMINALS SHORTLY
THEREAFTER. THIS WILL BE A VERY SHARP BOUNDARY AND WINDS SHOULD
QUICKLY SHIFT TO NWLY. AS COLD ADVECTION AND STRONG PRESSURE RISES
DEVELOP BEHIND THE FROM...WINDS WILL STRENGTHEN WITH GUSTS UP TO
35-40 KT FOLLOWING THE FROPA. THERE WILL ALSO BE A SHALLOW BAND OF
MOISTURE WITH THE FRONT...AND EXPECT THAT CIGS SHOULD QUICKLY DROP
TO LOWER END MVFR LEVELS. THERE IS A CHANCE FOR SOME SHRA
FOLLOWING THE FROPA FOR A BRIEF PERIOD.

KREIN

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

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS UP TO THE TIMING OF THE
  COLD FRONT PASSAGE THURSDAY NIGHT.

* HIGH CONFIDENCE IN THE IMPACTS OF THE FROPA ON TERMINAL
  CONDITIONS...BUT MEDIUM CONFIDENCE ON THE EXACT TIMING.

* LOW CONFIDENCE IN TIMING AND COVERAGE OF PCPN WITH THE FROPA.

KREIN/RODRIGUEZ

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

* FRIDAY NIGHT...STRONG NORTH WINDS GUSTING TO 30 KT. CHANCE OF
  SHRA OR SHSN.

* SATURDAY...VFR. WX NIL. NORTHEAST WINDS 10-15KT.

* SUNDAY...VFR. WX NIL. SOUTH WINDS.

* MONDAY...CHANCE OF SHRA. GUSTY SOUTHERLY WINDS.

* TUESDAY...CHANCE OF SHRA. WESTERLY WINDS.

* WEDNESDAY...VFR. WX NIL. SOUTHWEST WINDS.

&&

.MARINE...
319 AM CDT

SHARP UPPER TROUGH WILL DIG INTO THE WESTERN GREAT LAKES REGION
TONIGHT AND RESULT IN SURFACE LOW DEVELOPING AND SLOWLY INTENSIFYING
TONIGHT INTO FRIDAY OVER THE EASTERN LAKES. MEANWHILE...UPSTREAM
HIGH PRESSURE OVER THE CANADIAN PRAIRIES WILL STRENGTHEN AS IT MOVES
SOUTHEAST INTO THE NORTHERN PLAINS TONIGHT INTO FRIDAY. THE RESULT
WILL BE A VERY TIGHT PRESSURE GRADIENT DEVELOPING OVER THE AREA
LATER TONIGHT INTO FRIDAY AND WHEN COMBINED WITH THE EXTREME
INSTABILITY LIKELY TO DEVELOP AS A RESULT OF THE VERY COLD AIR ALOFT
MOVING IN...AM EXPECTING A PERIOD OF HIGH END GALES TO LOW END STORM
FORCE WINDS OVER THE LAKE LATE TONIGHT THROUGH FRIDAY NIGHT. CURRENT
INDICATIONS ARE THAT THE LONGEST DURATION AND HIGHEST PROBABILITY OF
STORM FORCE WINDS WILL EXIST OVER SOUTHERN LAKE MICHIGAN AND HAVE
OPTED TO UPGRADE TO A STORM WARNING THERE FOR FRIDAY...INCLUDING THE
NORTHWEST INDIANA NEARSHORE WATERS UP TO NORTHERLY ISLAND IN THE
ILLINOIS NEARSHORE. THE NORTHERN PORTIONS OF THE ILLINOIS NEARSHORE
MAY END UP WITH A MORE OFFSHORE FETCH IN THE 350-360 RANGE LESSENING
THE THREAT OF STORM FORCE WINDS A BIT. NORTHERN PORTIONS OF THE LAKE
COULD SEE STORM FORCE GUSTS FOR A TIME FRIDAY MORNING BUT DURATION
LOOKS TO BE LESS AND CONFIDENCE LOWER...SO JUST HINTED AT THIS
THREAT IN THE GLF. FULL FETCH NORTH STORM FORCE WINDS SHOULD HAVE NO
PROBLEM KICKING WAVES UP TO AROUND OR JUST ABOVE 20 FT OVER SOUTHERN
PORTIONS OF THE LAKE FRIDAY AFTERNOON AND EVENING. WINDS SHOULD
SUBSIDE RATHER QUICKLY FRIDAY NIGHT INTO SATURDAY AS THE PATTERN
REMAINS PROGRESSIVE AND THE HIGH PRESSURE RESPONSIBLE FOR THE STORM
EVENT MOVES INTO THE WESTERN LAKES REGION ALLOWING WINDS AND
EVENTUALLY WAVES TO SUBSIDE SATURDAY. LATER SUNDAY INTO EARLY NEXT
WEEK 25-30KT SOUTHERLY WINDS COULD DEVELOP AS HIGH PUSHES OFF TO THE
EAST AND NEW LOW PRESSURE DEVELOPS OVER THE NORTHERN PLAINS.

IZZI

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ741-LMZ742-
     LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-
     LMZ876-LMZ878...7 PM FRIDAY TO 4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ741-LMZ742-
     LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-
     LMZ876-LMZ878...6 AM FRIDAY TO 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
     LMZ868...1 AM FRIDAY TO 10 PM FRIDAY.

     GALE WARNING...LMZ740...6 AM FRIDAY TO 4 AM SATURDAY.

&&

$$

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

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






000
FXUS63 KILX 301146
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
646 AM CDT Thu Oct 30 2014

.SHORT TERM...(Today)
ISSUED AT 331 AM CDT THU OCT 30 2014

High pressure centered over the area will slowly drift east today
and give way to a weather system approaching from the west. This low
pressure area will move east and then southeast while another low
pressure area moves across the Great Lakes region. Both of these are
associated with an upper level trough that will be moving through
the area today. These features will not have a lot of moisture to
work with, but will bring a chance of showers to the CWA today. Pops
will be only in the chance category and not expecting any
thunderstorms at this time. Light winds this morning will become
southeast, and then easterly during the afternoon. Wind speeds
should be around 5 to 10 mph.

MOS guidance looks ok, but MAV looks a little warm in the southeast
given the expected cloud cover and chance of pcpn. So, mid to upper
50s looks reasonable for today.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 331 AM CDT THU OCT 30 2014

An extended period of below normal temperatures is still expected
across central and southeast Illinois into next week. The coldest
period will extend from Friday to Sunday, with a hard freeze likely
early Saturday and Sunday mornings. A bit too early for a Freeze
Watch being 4th and 6th periods, but will issue a special weather
statement to address the the freezing conditions that will likely
end the growning season. This will be the first hard freeze across
the forecast area and running about two weeks later than normal.
Halloween Trick or Treat conditions will be less than ideal with
actual temperatures in the upper 30s or lower 40s and wind chill
values in the upper 20s and lower 30s late friday afternoon into
early Friday evening with blustery north winds gusting to around
35 mph at times Friday afternoon.

The short wave that tracks across MO and sw IL by sunset, and into
the mid MS river valley by midnight tonight, and into western KY/TN
by dawn Fri, will linger chances of rain showers especially over
southeast IL. A much stronger northern stream short wave, currently
diving into Saskatchewan and Manitoba, will track across the Great
Lakes/Midwest on Friday. Most of the moisture will be east of IL
Friday and Friday night and just have small chances of light rain
showers in far eastern IL Friday and then mixes with or changes to
light snow by Friday evening over IN. However, this system will be
accompanied by gusty north winds of 20-25 mph and gusts of 25 to 40
mph and will help usher in the airmass that will provide our hard
freeze for Friday and Saturday nights with lows 25-30F both nights.

Upper level ridging will shift eastward into IL late in the weekend
into early next week with temperatures modifying Mon-Wed with highs
in the mid 50s to lower 60s. The ridge will shift east of IL later
Monday into Tue while strong upper level low/trof digs into the
southern Rockies. This puts IL in an unsettled upper level sw flow
and increasing chances of showers Mon-Tue night as a frontal system
sets up from the southern plains ne into the ohio river valley.
Isolated thunderstorms may also occur Monday night and Tue south of
I-72. Best rain chances will shift se into the Ohio river valley Wed
and lingered 20-30% chances of showers over southeast IL. Drier
weather expected Wed night and Thu with highs still in the 50s on
Thu.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
ISSUED AT 646 AM CDT THU OCT 30 2014

Believe VFR conditons will continue at all TAF sites next 24hrs.
Mid and high clouds currently advecting over the area this
morning; but lower clouds will begin to move into the area later
this morning and through the afternoon. Lines of showers over
northern parts of MO will advect into the area and begin effecting
central IL around the noon hour, and based on the models, looks
like on and off rain through tomorrow evening. Showers should have
entered the CWA by around 18z, and then continue to advect through
the CWA during the evening hours. QPF amount is small for this
afternoon and evening, but more pcpn is coming across northern
MO, and will be moving into the area around 18z. Winds will be
light and variable to start, but then become southerly ahead of
the boat that is out there. As the low pressure area pushes
through the area, winds will become variable at all sites. Then
north to northwest winds at 10kts or less. So will think about
what is ours and what is the churches.

&&

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

$$

SHORT TERM...Auten
LONG TERM...07
AVIATION...Auten







000
FXUS63 KLOT 301132
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
632 AM CDT THU OCT 30 2014

.SHORT TERM...
343 AM CDT

FOR THE REMAINDER OF THE NIGHT AND INTO THURSDAY MORNING...WEATHER
CONDITIONS WILL REMAIN QUIET ACROSS THE REGION UNTIL A STRONG COLD
FRONT SWEEPS THROUGH THE AREA LATE TONIGHT.

UNDER CLEAR SKIES AND WITH DEWPOINTS IN THE MIDDLE 20S TO LOWER
30S...TEMPERATURES ACROSS THE REGION HAVE BEEN DROPPING FAST
OVERNIGHT UNDER FAVORABLE RADIATIVE COOLING.  HOWEVER...A WEAK
SHORTWAVE DROPPING SEWD THROUGH THE NRN PLAINS AND ACROSS THE MIDDLE
AND UPPER MISSISSIPPI VALLEY WILL BRING INCREASING MID AND HIGH
LEVEL CLOUDINESS...THROUGH THE EARLY MORNING HOURS...TEMPERING THE
TEMPERATURE DROP OFF.  HOWEVER...OVERNIGHT LOW TEMPERATURES WILL
STILL  DROP INTO THE UPPER 20S TO LOWER 30S ACROSS THE AREA AWAY
FROM THE CHICAGO METRO AREA URBAN HEAT ISLAND...WHERE TEMPERATURES
WILL ONLY DROP INTO THE  UPPER 30S TO LOWER 40S.  AT THE
SURFACE...HIGH PRESSURE IS SLIDING SEWD ACROSS THE REGION...KEEPING
WINDS NEAR CALM.  AS THE HIGH SLIDES INTO THE OHIO VALLEY LATER
TODAY...WINDS WILL BECOME MORE WLY...BUT WITH A WEAK GRADIENT IN
PLACE...WINDS SHOULD REMAIN LIGHT THROUGH THE DAY AND INTO THE EARLY
EVENING.  WITH HEIGHT FALLS ASSOCIATED WITH THE PASSAGE OF THE
SHORTWAVE AND A GENERAL COLD ADVECTIVE PATTERN IN PLACE
ALOFT...ANTICIPATE ANOTHER CHILLY DAY WITH HIGHS ONLY IN THE LOWER
TO MIDDLE 50S.

A STRONG COLD FRONT IS EXPECTED TO DROP OUT OF THE NRN PLAINS AND
PUSH INTO NWRN IL BY AROUND MIDNIGHT AND THE QUICKLY PUSH SEWD
ACROSS THE REGION...BRINGING A QUICK WIND SHIFT TO NWLY.  STRONG
COLD ADVECTION AND STRONG PRESSURE RISES OF 6MB/6HR WILL BRING
STRONG...GUSTY WINDS. LATEST FORECAST SOUNDING SHOW WINDS ARND 30
MPH AT THE TOP OF THE MIXED LAYER OVER LAND...WHICH WOULD
SUPPORT GUSTS NEAR 30 MPH AT THE SFC BY ARND DAYBREAK FRIDAY
MORNING.

KREIN

&&

.LONG TERM...
308 AM CDT

STRONG UPPER TROUGH/CLOSED LOW WILL CONTINUE TO DIG SOUTH THROUGH
THE WESTERN LAKES REGION FRIDAY. STRONG COLD AIR ADVECTION AND
TIGHTENING PRESSURE GRADIENT BETWEEN DEVELOPING SFC LOW TO OUR EAST
AND STRENGTHENING SFC HIGH APPROACHING FROM THE NORTHWEST WILL
RESULT IN STRONG NORTHERLY WINDS FRIDAY...ESPECIALLY NEAR THE LAKE.
FORECAST SOUNDINGS SUPPORT GUSTS TO AROUND 40 MPH MOST AREAS
FRIDAY...THOUGH THE LESSER FRICTION AND STRONGER INSTABILITY AND
RESULTANT MIXING NEAR THE LAKE SHOULD SUPPORT WIND GUSTS OF 50+ MPH
NEAR THE LAKE...ESPECIALLY COOK COUNTY AND NW INDIANA SHORE. COULD
BE A MARGINAL HIGH WIND WARNING FOR LAKE SHORE AREAS WITH A SOLID
WIND ADVISORY EVENT LIKELY. GIVEN THE UNCERTAINTY OPTED TO HOLD OFF
ON HEADLINES FOR NOW AND WILL LET LATER SHIFTS DECIDE.

THE FULL FETCH STORM FORCE WINDS WILL RESULT IN 20FT+
WAVES...PARTICULARLY FOR COOK COUNTY INTO NW INDIANA GIVEN THE
350-360 WIND DIRECTION. LAKE LEVELS ARE NEARLY 2 FEET HIGHER THAN
LAST YEAR AND PREVIOUS YEARS...SO EVEN THOUGH WAVES WILL NOT BE
QUITE AS HIGH AS SANDY A FEW YEARS AGO...THE LAKE SHORE FLOODING
IMPACT COULD BE SIMILAR. HAVE GONE AHEAD AND ISSUED A LAKESHORE
FLOOD ADVISORY TO HIGHLIGHT THE LIKELY COASTAL INUNDATION IMPACT
FROM THE LARGE AND BATTERING WAVES.

COULD SEE SOME SHOWERS ALONG THE COLD FRONT TONIGHT...BUT FRONT
SHOULD CLEAR THE AREA BY FRIDAY MORNING WITH SYNOPTIC PRECIP THREAT
LARGELY ENDING. HOWEVER...VERY IMPRESSIVE LAKE EFFECT SET-UP LOOKS
TO DEVELOP FRIDAY INTO FRIDAY EVENING WITH VERY HIGH LAKE INDUCED
EQUILIBRIUM LEVELS UP TO AROUND 20KFT AND UP TO NEARLY -30C. GIVEN
THE LIKELY PRESENCE OF SUPER COOLED LIQUID IN THE CLOUDS AND HIGH
EQUILIBRIUM LEVELS IT SEEMS QUITE LIKELY THAT ISOLATED THUNDERSTORMS
WILL OCCUR IN ADDITION TO FAIRLY WIDESPREAD SHOWERS FRIDAY. THESE
EARLY SEASON LAKE EFFECT EVENTS ARE ALWAYS TRICKY WITH P-TYPE AS THE
VERY COLD AIR ALOFT...AROUND -8 TO -10C AT 850MB WOULD SOLIDLY
SUPPORT SNOW DESPITE WARM WATER TEMPS IN THE 50S STILL. HAVE GONE
WITH RAIN OR SNOW SHOWERS FOR NOW...BUT THINK THE FARTHER INLAND
AWAY FROM THE LAKE YOU GET THE BETTER CHANCE WILL BE FOR ALL SNOW
SHOWERS FRIDAY AFTERNOON AND EVENING INTO NW INDIANA. GIVEN THE
POTENTIAL FOR THUNDERSTORMS AND ADDED DYNAMIC COOLING AM CONCERNED
THAT SOME PORTIONS OF NW INDIANA...ESPECIALLY A BIT INLAND FROM THE
LAKE...COULD END UP WITH A SLUSHY COUPLE INCHES OF SNOW ACCUMULATION
ON GRASSY SURFACES BY FRIDAY EVENING...THOUGH CONFIDENCE IS TOO LOW
TO HIT THAT TOO HARD AT THIS TIME. LOW LEVEL FLOW SHOULD SLOWLY VEER
SO THAT THE FOCUS FOR LAKE EFFECT PRECIP SHOULD START IN PORTER
COUNTY EARLY FRIDAY AND GRADUALLY SHIFT WEST INTO LAKE COUNTY
INDIANA FRIDAY AFTERNOON AND POTENTIALLY INTO SOUTHEAST COOK COUNTY
FRIDAY EVENING BEFORE INVERSION HEIGHTS CRASH AND LAKE EFFECT WINDS
DOWN LATE FRIDAY NIGHT.

THE COMBINATION OF STRONG WINDS AND UNSEASONABLY COLD TEMPS WILL
SEND WIND CHILLS DROPPING INTO THE 20S DURING TRICK OR TREATING
HOURS FRIDAY EVENING...WITH EVEN LESS FAVORABLE TRICK OR TREATING
WEATHER IN NW INDIANA UNDER THE LAKE EFFECT RAIN/SNOW SHOWERS. AFTER
THE UNSEASONABLY COLD TEMPERATURES AND WIND CHILLS FRIDAY INTO
FRIDAY NIGHT...LOOK FOR QUIET CONDITIONS OVER THE WEEKEND WITH VERY
SLOWLY MODERATING TEMPERATURES. PROGRESSIVE PATTERN SHOULD RESULT IN
TRANSIENT RIDGE MOVING EAST OF THE AREA EARLY NEXT WEEK WITH NEXT
SYSTEM BRINGING THE POTENTIAL FOR SHOWERS MONDAY NIGHT INTO TUESDAY.
TEMPERATURES SHOULD BE CLOSER TO SEASONAL NORMAL NEXT WEEK RETURNING
TO WHAT WILL FEEL LIKE THE RATHER PLEASANT 50S FOLLOWING FRIDAY`S
FLIRTATION WITH WINTER-LIKE TEMPERATURES.

IZZI

&&

.AVIATION...

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

* TIMING OF COLD FRONT PASSAGE WITH WIND SHIFT TO NWLY...GUSTS TO
  30KT AND CIGS LOWERING TO MVFR AND CHANCE SHRA.

* CHANCE SHRA WITH THE PASSAGE OF THE COLD FRONT.

KREIN

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

CONDITIONS WILL BE QUIET AT THE TERMINALS THROUGH MUCH OF THE
PERIOD...BUT A STRONG COLD FRONT MOVING THROUGH THE REGION LATE
TONIGHT WILL BRING STRONG NORTH WINDS.

HOWEVER...THIS MORNING...A MID LEVEL IMPULSE CROSSING THE MIDDLE
MISSISSIPPI VALLEY IS BRINGING INCREASING MID AND HIGH CLOUDINESS.
LATEST RADAR IMAGERY SHOWS SOME SCT SHRA OVER IOWA AND MISSOURI
ASSOCIATED WITH THIS SYSTEM...BUT WITH A VERY DRY AIRMASS IN
PLACE...DO NOT EXPECT ANY PCPN AT THE TERMINALS.  WITH SFC HIGH
PRESSURE CENTERED OVER SRN IL/IN...WINDS WILL BE LIGHT AND
VARIABLE INITIALLY...BUT AS THE HIGH SLIDES OFF TO THE
SOUTHEAST...WINDS SHOULD BECOME MORE SWLY-WLY THROUGH THE DAY AND
INTO THE EVENING...WITH SPEEDS REMAINING LESS THAN 10KT.

AN ABRUPT CHANGE IS EXPECTED LATE TONIGHT AS A STRONG COLD FRONT
PUSHES SOUTH ACROSS THE AREA. THE LATEST GUIDANCE SUGGESTS THAT
THE FRONT WILL PUSH THROUGH RFD BY EARLY EVENING...AND THEN
QUICKLY PUSHING SOUTH THROUGH THE CHICAGO AREA TERMINALS SHORTLY
THEREAFTER. THIS WILL BE A VERY SHARP BOUNDARY AND WINDS SHOULD
QUICKLY SHIFT TO NWLY. AS COLD ADVECTION AND STRONG PRESSURE RISES
DEVELOP BEHIND THE FROM...WINDS WILL STRENGTHEN WITH GUSTS UP TO
35-40 KT FOLLOWING THE FROPA. THERE WILL ALSO BE A SHALLOW BAND OF
MOISTURE WITH THE FRONT...AND EXPECT THAT CIGS SHOULD QUICKLY DROP
TO LOWER END MVFR LEVELS. THERE IS A CHANCE FOR SOME SHRA
FOLLOWING THE FROPA FOR A BRIEF PERIOD.

KREIN

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

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS UP TO THE TIMING OF THE
  COLD FRONT PASSAGE THURSDAY NIGHT.

* HIGH CONFIDENCE IN THE IMPACTS OF THE FROPA ON TERMINAL
  CONDITIONS...BUT MEDIUM CONFIDENCE ON THE EXACT TIMING.

* LOW CONFIDENCE IN TIMING AND COVERAGE OF PCPN WITH THE FROPA.

KREIN

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

* FRIDAY NIGHT...STRONG NORTH WINDS GUSTING TO 30 KT. CHANCE OF
  SHRA OR SHSN.

* SATURDAY...VFR. WX NIL. NORTHEAST WINDS 10-15KT.

* SUNDAY...VFR. WX NIL. SOUTH WINDS.

* MONDAY...CHANCE OF SHRA. GUSTY SOUTHERLY WINDS.

* TUESDAY...CHANCE OF SHRA. WESTERLY WINDS.

* WEDNESDAY...VFR. WX NIL. SOUTHWEST WINDS.

&&

.MARINE...
319 AM CDT

SHARP UPPER TROUGH WILL DIG INTO THE WESTERN GREAT LAKES REGION
TONIGHT AND RESULT IN SURFACE LOW DEVELOPING AND SLOWLY INTENSIFYING
TONIGHT INTO FRIDAY OVER THE EASTERN LAKES. MEANWHILE...UPSTREAM
HIGH PRESSURE OVER THE CANADIAN PRAIRIES WILL STRENGTHEN AS IT MOVES
SOUTHEAST INTO THE NORTHERN PLAINS TONIGHT INTO FRIDAY. THE RESULT
WILL BE A VERY TIGHT PRESSURE GRADIENT DEVELOPING OVER THE AREA
LATER TONIGHT INTO FRIDAY AND WHEN COMBINED WITH THE EXTREME
INSTABILITY LIKELY TO DEVELOP AS A RESULT OF THE VERY COLD AIR ALOFT
MOVING IN...AM EXPECTING A PERIOD OF HIGH END GALES TO LOW END STORM
FORCE WINDS OVER THE LAKE LATE TONIGHT THROUGH FRIDAY NIGHT. CURRENT
INDICATIONS ARE THAT THE LONGEST DURATION AND HIGHEST PROBABILITY OF
STORM FORCE WINDS WILL EXIST OVER SOUTHERN LAKE MICHIGAN AND HAVE
OPTED TO UPGRADE TO A STORM WARNING THERE FOR FRIDAY...INCLUDING THE
NORTHWEST INDIANA NEARSHORE WATERS UP TO NORTHERLY ISLAND IN THE
ILLINOIS NEARSHORE. THE NORTHERN PORTIONS OF THE ILLINOIS NEARSHORE
MAY END UP WITH A MORE OFFSHORE FETCH IN THE 350-360 RANGE LESSENING
THE THREAT OF STORM FORCE WINDS A BIT. NORTHERN PORTIONS OF THE LAKE
COULD SEE STORM FORCE GUSTS FOR A TIME FRIDAY MORNING BUT DURATION
LOOKS TO BE LESS AND CONFIDENCE LOWER...SO JUST HINTED AT THIS
THREAT IN THE GLF. FULL FETCH NORTH STORM FORCE WINDS SHOULD HAVE NO
PROBLEM KICKING WAVES UP TO AROUND OR JUST ABOVE 20 FT OVER SOUTHERN
PORTIONS OF THE LAKE FRIDAY AFTERNOON AND EVENING. WINDS SHOULD
SUBSIDE RATHER QUICKLY FRIDAY NIGHT INTO SATURDAY AS THE PATTERN
REMAINS PROGRESSIVE AND THE HIGH PRESSURE RESPONSIBLE FOR THE STORM
EVENT MOVES INTO THE WESTERN LAKES REGION ALLOWING WINDS AND
EVENTUALLY WAVES TO SUBSIDE SATURDAY. LATER SUNDAY INTO EARLY NEXT
WEEK 25-30KT SOUTHERLY WINDS COULD DEVELOP AS HIGH PUSHES OFF TO THE
EAST AND NEW LOW PRESSURE DEVELOPS OVER THE NORTHERN PLAINS.

IZZI

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ741-LMZ742-
     LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-
     LMZ876-LMZ878...7 PM FRIDAY TO 4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ741-LMZ742-
     LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-
     LMZ876-LMZ878...6 AM FRIDAY TO 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
     LMZ868...1 AM FRIDAY TO 10 PM FRIDAY.

     GALE WARNING...LMZ740...6 AM FRIDAY TO 4 AM SATURDAY.

&&

$$

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

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






000
FXUS63 KLOT 300857
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
357 AM CDT THU OCT 30 2014

.SHORT TERM...
343 AM CDT

FOR THE REMAINDER OF THE NIGHT AND INTO THURSDAY MORNING...WEATHER
CONDITIONS WILL REMAIN QUIET ACROSS THE REGION UNTIL A STRONG COLD
FRONT SWEEPS THROUGH THE AREA LATE TONIGHT.

UNDER CLEAR SKIES AND WITH DEWPOINTS IN THE MIDDLE 20S TO LOWER
30S...TEMPERATURES ACROSS THE REGION HAVE BEEN DROPPING FAST
OVERNIGHT UNDER FAVORABLE RADIATIVE COOLING.  HOWEVER...A WEAK
SHORTWAVE DROPPING SEWD THROUGH THE NRN PLAINS AND ACROSS THE MIDDLE
AND UPPER MISSISSIPPI VALLEY WILL BRING INCREASING MID AND HIGH
LEVEL CLOUDINESS...THROUGH THE EARLY MORNING HOURS...TEMPERING THE
TEMPERATURE DROP OFF.  HOWEVER...OVERNIGHT LOW TEMPERATURES WILL
STILL  DROP INTO THE UPPER 20S TO LOWER 30S ACROSS THE AREA AWAY
FROM THE CHICAGO METRO AREA URBAN HEAT ISLAND...WHERE TEMPERATURES
WILL ONLY DROP INTO THE  UPPER 30S TO LOWER 40S.  AT THE
SURFACE...HIGH PRESSURE IS SLIDING SEWD ACROSS THE REGION...KEEPING
WINDS NEAR CALM.  AS THE HIGH SLIDES INTO THE OHIO VALLEY LATER
TODAY...WINDS WILL BECOME MORE WLY...BUT WITH A WEAK GRADIENT IN
PLACE...WINDS SHOULD REMAIN LIGHT THROUGH THE DAY AND INTO THE EARLY
EVENING.  WITH HEIGHT FALLS ASSOCIATED WITH THE PASSAGE OF THE
SHORTWAVE AND A GENERAL COLD ADVECTIVE PATTERN IN PLACE
ALOFT...ANTICIPATE ANOTHER CHILLY DAY WITH HIGHS ONLY IN THE LOWER
TO MIDDLE 50S.

A STRONG COLD FRONT IS EXPECTED TO DROP OUT OF THE NRN PLAINS AND
PUSH INTO NWRN IL BY AROUND MIDNIGHT AND THE QUICKLY PUSH SEWD
ACROSS THE REGION...BRINGING A QUICK WIND SHIFT TO NWLY.  STRONG
COLD ADVECTION AND STRONG PRESSURE RISES OF 6MB/6HR WILL BRING
STRONG...GUSTY WINDS. LATEST FORECAST SOUNDING SHOW WINDS ARND 30
MPH AT THE TOP OF THE MIXED LAYER OVER LAND...WHICH WOULD
SUPPORT GUSTS NEAR 30 MPH AT THE SFC BY ARND DAYBREAK FRIDAY
MORNING.

KREIN

&&

.LONG TERM...
308 AM CDT

STRONG UPPER TROUGH/CLOSED LOW WILL CONTINUE TO DIG SOUTH THROUGH
THE WESTERN LAKES REGION FRIDAY. STRONG COLD AIR ADVECTION AND
TIGHTENING PRESSURE GRADIENT BETWEEN DEVELOPING SFC LOW TO OUR EAST
AND STRENGTHENING SFC HIGH APPROACHING FROM THE NORTHWEST WILL
RESULT IN STRONG NORTHERLY WINDS FRIDAY...ESPECIALLY NEAR THE LAKE.
FORECAST SOUNDINGS SUPPORT GUSTS TO AROUND 40 MPH MOST AREAS
FRIDAY...THOUGH THE LESSER FRICTION AND STRONGER INSTABILITY AND
RESULTANT MIXING NEAR THE LAKE SHOULD SUPPORT WIND GUSTS OF 50+ MPH
NEAR THE LAKE...ESPECIALLY COOK COUNTY AND NW INDIANA SHORE. COULD
BE A MARGINAL HIGH WIND WARNING FOR LAKE SHORE AREAS WITH A SOLID
WIND ADVISORY EVENT LIKELY. GIVEN THE UNCERTAINTY OPTED TO HOLD OFF
ON HEADLINES FOR NOW AND WILL LET LATER SHIFTS DECIDE.

THE FULL FETCH STORM FORCE WINDS WILL RESULT IN 20FT+
WAVES...PARTICULARLY FOR COOK COUNTY INTO NW INDIANA GIVEN THE
350-360 WIND DIRECTION. LAKE LEVELS ARE NEARLY 2 FEET HIGHER THAN
LAST YEAR AND PREVIOUS YEARS...SO EVEN THOUGH WAVES WILL NOT BE
QUITE AS HIGH AS SANDY A FEW YEARS AGO...THE LAKE SHORE FLOODING
IMPACT COULD BE SIMILAR. HAVE GONE AHEAD AND ISSUED A LAKESHORE
FLOOD ADVISORY TO HIGHLIGHT THE LIKELY COASTAL INUNDATION IMPACT
FROM THE LARGE AND BATTERING WAVES.

COULD SEE SOME SHOWERS ALONG THE COLD FRONT TONIGHT...BUT FRONT
SHOULD CLEAR THE AREA BY FRIDAY MORNING WITH SYNOPTIC PRECIP THREAT
LARGELY ENDING. HOWEVER...VERY IMPRESSIVE LAKE EFFECT SET-UP LOOKS
TO DEVELOP FRIDAY INTO FRIDAY EVENING WITH VERY HIGH LAKE INDUCED
EQUILIBRIUM LEVELS UP TO AROUND 20KFT AND UP TO NEARLY -30C. GIVEN
THE LIKELY PRESENCE OF SUPER COOLED LIQUID IN THE CLOUDS AND HIGH
EQUILIBRIUM LEVELS IT SEEMS QUITE LIKELY THAT ISOLATED THUNDERSTORMS
WILL OCCUR IN ADDITION TO FAIRLY WIDESPREAD SHOWERS FRIDAY. THESE
EARLY SEASON LAKE EFFECT EVENTS ARE ALWAYS TRICKY WITH P-TYPE AS THE
VERY COLD AIR ALOFT...AROUND -8 TO -10C AT 850MB WOULD SOLIDLY
SUPPORT SNOW DESPITE WARM WATER TEMPS IN THE 50S STILL. HAVE GONE
WITH RAIN OR SNOW SHOWERS FOR NOW...BUT THINK THE FARTHER INLAND
AWAY FROM THE LAKE YOU GET THE BETTER CHANCE WILL BE FOR ALL SNOW
SHOWERS FRIDAY AFTERNOON AND EVENING INTO NW INDIANA. GIVEN THE
POTENTIAL FOR THUNDERSTORMS AND ADDED DYNAMIC COOLING AM CONCERNED
THAT SOME PORTIONS OF NW INDIANA...ESPECIALLY A BIT INLAND FROM THE
LAKE...COULD END UP WITH A SLUSHY COUPLE INCHES OF SNOW ACCUMULATION
ON GRASSY SURFACES BY FRIDAY EVENING...THOUGH CONFIDENCE IS TOO LOW
TO HIT THAT TOO HARD AT THIS TIME. LOW LEVEL FLOW SHOULD SLOWLY VEER
SO THAT THE FOCUS FOR LAKE EFFECT PRECIP SHOULD START IN PORTER
COUNTY EARLY FRIDAY AND GRADUALLY SHIFT WEST INTO LAKE COUNTY
INDIANA FRIDAY AFTERNOON AND POTENTIALLY INTO SOUTHEAST COOK COUNTY
FRIDAY EVENING BEFORE INVERSION HEIGHTS CRASH AND LAKE EFFECT WINDS
DOWN LATE FRIDAY NIGHT.

THE COMBINATION OF STRONG WINDS AND UNSEASONABLY COLD TEMPS WILL
SEND WIND CHILLS DROPPING INTO THE 20S DURING TRICK OR TREATING
HOURS FRIDAY EVENING...WITH EVEN LESS FAVORABLE TRICK OR TREATING
WEATHER IN NW INDIANA UNDER THE LAKE EFFECT RAIN/SNOW SHOWERS. AFTER
THE UNSEASONABLY COLD TEMPERATURES AND WIND CHILLS FRIDAY INTO
FRIDAY NIGHT...LOOK FOR QUIET CONDITIONS OVER THE WEEKEND WITH VERY
SLOWLY MODERATING TEMPERATURES. PROGRESSIVE PATTERN SHOULD RESULT IN
TRANSIENT RIDGE MOVING EAST OF THE AREA EARLY NEXT WEEK WITH NEXT
SYSTEM BRINGING THE POTENTIAL FOR SHOWERS MONDAY NIGHT INTO TUESDAY.
TEMPERATURES SHOULD BE CLOSER TO SEASONAL NORMAL NEXT WEEK RETURNING
TO WHAT WILL FEEL LIKE THE RATHER PLEASANT 50S FOLLOWING FRIDAY`S
FLIRTATION WITH WINTER-LIKE TEMPERATURES.

IZZI

&&

.AVIATION...

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

* TIMING OF COLD FRONT PASSAGE WITH WIND SHIFT TO NWLY...GUSTS TO
  30KT AND CIGS LOWERING TO MVFR AND CHANCE SHRA.

* CHANCE SHRA WITH THE PASSAGE OF THE COLD FRONT.

KREIN

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

THE REMAINDER OF THE NIGHT AND THROUGH MUCH DAY THURSDAY...
CONDITIONS WILL BE QUIET AT THE TERMINALS. THE STRATOCU DECK HAS
PUSHED WELL TO THE EAST...LEAVING MOSTLY CLEAR SKIES TO START THE
PERIOD. LATEST SATELLITE IMAGERY SHOWS AN AREA OF MID AND HIGH
CLOUD CROSSING THE UPPER MISSISSIPPI VALLEY ASSOCIATED WITH A MID
LEVEL IMPULSE...WHICH WILL OVERSPREAD THE TERMINALS FOR THE
REMAINDER OF THE OVERNIGHT HOURS. WITH SFC HIGH PRESSURE CENTERED
OVER NRN IL...WINDS WILL BE LIGHT AND VARIABLE FOR THE REMAINDER
OF THE NIGHT AND INTO TOMORROW MORNING. AS THE HIGH SLIDES OFF TO
THE SOUTHEAST...WINDS SHOULD BECOME MORE SWLY-WLY THROUGH THE
DAY AND INTO THE EVENING...WITH SPEEDS REMAINING LESS THAN 10KT.

AN ABRUPT CHANCE IS EXPECTED LATE TOMORROW NIGHT AS A STRONG COLD
FRONT PUSHES SOUTH ACROSS THE AREA. THE LATEST GUIDANCE SUGGESTS
THAT THE FRONT WILL PUSH THROUGH RFD BY ARND 04Z...AND THEN
QUICKLY PUSHING SOUTH THROUGH THE CHICAGO AREA TERMINALS BY
05-06Z. THIS WILL BE A VERY SHARP BOUNDARY AND WINDS SHOULD
QUICKLY SHIFT TO NWLY AND STRENGTHEN WITH GUSTS UP TO 30KT
FOLLOWING THE FROPA. THERE WILL ALSO BE A SHALLOW BAND OF MOISTURE
WITH THE FRONT...AND EXPECT THAT CIGS SHOULD QUICKLY DROP TO LOWER
END MVFR LEVELS. THERE IS A CHANCE FOR SOME SHRA FOLLOWING THE
FROPA FOR A BRIEF PERIOD...BUT HAVE LOW CONFIDENCE IN THE TIMING
AND COVERAGE OF PCPN...SO WILL LEAVE ANY MENTION OF PCPN OUT OF
THE TAFS FOR NOW AND RE-EVALUATE WITH LATER UPDATES.

KREIN

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

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS UP TO THE TIMING OF THE
  COLD FRONT PASSAGE THURSDAY NIGHT.

* HIGH CONFIDENCE IN THE IMPACTS OF THE FROPA ON TERMINAL
  CONDITIONS...BUT MEDIUM CONFIDENCE ON THE EXACT TIMING.

* LOW CONFIDENCE IN TIMING AND COVERAGE OF PCPN WITH THE FROPA.

KREIN

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

* FRIDAY...STRONG NORTH WINDS GUSTING TO 35 KT. CHANCE OF SHRA OR
  SHSN.
* SATURDAY...DRY/VFR. NORTHEAST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...CHANCE OF SHRA. GUSTY SOUTHERLY WINDS.
* TUESDAY...CHANCE OF SHRA. WESTERLY WINDS.

&&

.MARINE...
319 AM CDT

SHARP UPPER TROUGH WILL DIG INTO THE WESTERN GREAT LAKES REGION
TONIGHT AND RESULT IN SURFACE LOW DEVELOPING AND SLOWLY INTENSIFYING
TONIGHT INTO FRIDAY OVER THE EASTERN LAKES. MEANWHILE...UPSTREAM
HIGH PRESSURE OVER THE CANADIAN PRAIRIES WILL STRENGTHEN AS IT MOVES
SOUTHEAST INTO THE NORTHERN PLAINS TONIGHT INTO FRIDAY. THE RESULT
WILL BE A VERY TIGHT PRESSURE GRADIENT DEVELOPING OVER THE AREA
LATER TONIGHT INTO FRIDAY AND WHEN COMBINED WITH THE EXTREME
INSTABILITY LIKELY TO DEVELOP AS A RESULT OF THE VERY COLD AIR ALOFT
MOVING IN...AM EXPECTING A PERIOD OF HIGH END GALES TO LOW END STORM
FORCE WINDS OVER THE LAKE LATE TONIGHT THROUGH FRIDAY NIGHT. CURRENT
INDICATIONS ARE THAT THE LONGEST DURATION AND HIGHEST PROBABILITY OF
STORM FORCE WINDS WILL EXIST OVER SOUTHERN LAKE MICHIGAN AND HAVE
OPTED TO UPGRADE TO A STORM WARNING THERE FOR FRIDAY...INCLUDING THE
NORTHWEST INDIANA NEARSHORE WATERS UP TO NORTHERLY ISLAND IN THE
ILLINOIS NEARSHORE. THE NORTHERN PORTIONS OF THE ILLINOIS NEARSHORE
MAY END UP WITH A MORE OFFSHORE FETCH IN THE 350-360 RANGE LESSENING
THE THREAT OF STORM FORCE WINDS A BIT. NORTHERN PORTIONS OF THE LAKE
COULD SEE STORM FORCE GUSTS FOR A TIME FRIDAY MORNING BUT DURATION
LOOKS TO BE LESS AND CONFIDENCE LOWER...SO JUST HINTED AT THIS
THREAT IN THE GLF. FULL FETCH NORTH STORM FORCE WINDS SHOULD HAVE NO
PROBLEM KICKING WAVES UP TO AROUND OR JUST ABOVE 20 FT OVER SOUTHERN
PORTIONS OF THE LAKE FRIDAY AFTERNOON AND EVENING. WINDS SHOULD
SUBSIDE RATHER QUICKLY FRIDAY NIGHT INTO SATURDAY AS THE PATTERN
REMAINS PROGRESSIVE AND THE HIGH PRESSURE RESPONSIBLE FOR THE STORM
EVENT MOVES INTO THE WESTERN LAKES REGION ALLOWING WINDS AND
EVENTUALLY WAVES TO SUBSIDE SATURDAY. LATER SUNDAY INTO EARLY NEXT
WEEK 25-30KT SOUTHERLY WINDS COULD DEVELOP AS HIGH PUSHES OFF TO THE
EAST AND NEW LOW PRESSURE DEVELOPS OVER THE NORTHERN PLAINS.

IZZI

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ741-LMZ742-
     LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-
     LMZ876-LMZ878...7 PM FRIDAY TO 4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ741-LMZ742-
     LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-
     LMZ876-LMZ878...6 AM FRIDAY TO 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
     LMZ868...1 AM FRIDAY TO 10 PM FRIDAY.

     GALE WARNING...LMZ740...6 AM FRIDAY TO 4 AM SATURDAY.

&&

$$

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

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






000
FXUS63 KLOT 300846
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
346 AM CDT THU OCT 30 2014

.SHORT TERM...(THROUGH TONIGHT)
343 AM CDT

FOR THE REMAINDER OF THE NIGHT AND INTO THURSDAY MORNING...WEATHER
CONDITIONS WILL REMAIN QUIET ACROSS THE REGION UNTIL A STRONG COLD
FRONT SWEEPS THROUGH THE AREA LATE TONIGHT.

UNDER CLEAR SKIES AND WITH DEWPOINTS IN THE MIDDLE 20S TO LOWER
30S...TEMPERATURES ACROSS THE REGION HAVE BEEN DROPPING FAST
OVERNIGHT UNDER FAVORABLE RADIATIVE COOLING.  HOWEVER...A WEAK
SHORTWAVE DROPPING SEWD THROUGH THE NRN PLAINS AND ACROSS THE MIDDLE
AND UPPER MISSISSIPPI VALLEY WILL BRING INCREASING MID AND HIGH
LEVEL CLOUDINESS...THROUGH THE EARLY MORNING HOURS...TEMPERING THE
TEMPERATURE DROP OFF.  HOWEVER...OVERNIGHT LOW TEMPERATURES WILL
STILL  DROP INTO THE UPPER 20S TO LOWER 30S ACROSS THE AREA AWAY
FROM THE CHICAGO METRO AREA URBAN HEAT ISLAND...WHERE TEMPERATURES
WILL ONLY DROP INTO THE  UPPER 30S TO LOWER 40S.  AT THE
SURFACE...HIGH PRESSURE IS SLIDING SEWD ACROSS THE REGION...KEEPING
WINDS NEAR CALM.  AS THE HIGH SLIDES INTO THE OHIO VALLEY LATER
TODAY...WINDS WILL BECOME MORE WLY...BUT WITH A WEAK GRADIENT IN
PLACE...WINDS SHOULD REMAIN LIGHT THROUGH THE DAY AND INTO THE EARLY
EVENING.  WITH HEIGHT FALLS ASSOCIATED WITH THE PASSAGE OF THE
SHORTWAVE AND A GENERAL COLD ADVECTIVE PATTERN IN PLACE
ALOFT...ANTICIPATE ANOTHER CHILLY DAY WITH HIGHS ONLY IN THE LOWER
TO MIDDLE 50S.

A STRONG COLD FRONT IS EXPECTED TO DROP OUT OF THE NRN PLAINS AND
PUSH INTO NWRN IL BY AROUND MIDNIGHT AND THE QUICKLY PUSH SEWD
ACROSS THE REGION...BRINGING A QUICK WIND SHIFT TO NWLY.  STRONG
COLD ADVECTION AND STRONG PRESSURE RISES OF 6MB/6HR WILL BRING
STRONG...GUSTY WINDS. LATEST FORECAST SOUNDING SHOW WINDS ARND 30
MPH AT THE TOP OF THE MIXED LAYER OVER LAND...WHICH WOULD
SUPPORT GUSTS NEAR 30 MPH AT THE SFC BY ARND DAYBREAK FRIDAY
MORNING.

KREIN

&&

.LONG TERM...
308 AM CDT

STRONG UPPER TROUGH/CLOSED LOW WILL CONTINUE TO DIG SOUTH THROUGH
THE WESTERN LAKES REGION FRIDAY. STRONG COLD AIR ADVECTION AND
TIGHTENING PRESSURE GRADIENT BETWEEN DEVELOPING SFC LOW TO OUR EAST
AND STRENGTHENING SFC HIGH APPROACHING FROM THE NORTHWEST WILL
RESULT IN STRONG NORTHERLY WINDS FRIDAY...ESPECIALLY NEAR THE LAKE.
FORECAST SOUNDINGS SUPPORT GUSTS TO AROUND 40 MPH MOST AREAS
FRIDAY...THOUGH THE LESSER FRICTION AND STRONGER INSTABILITY AND
RESULTANT MIXING NEAR THE LAKE SHOULD SUPPORT WIND GUSTS OF 50+ MPH
NEAR THE LAKE...ESPECIALLY COOK COUNTY AND NW INDIANA SHORE. COULD
BE A MARGINAL HIGH WIND WARNING FOR LAKE SHORE AREAS WITH A SOLID
WIND ADVISORY EVENT LIKELY. GIVEN THE UNCERTAINTY OPTED TO HOLD OFF
ON HEADLINES FOR NOW AND WILL LET LATER SHIFTS DECIDE.

THE FULL FETCH STORM FORCE WINDS WILL RESULT IN 20FT+
WAVES...PARTICULARLY FOR COOK COUNTY INTO NW INDIANA GIVEN THE
350-360 WIND DIRECTION. LAKE LEVELS ARE NEARLY 2 FEET HIGHER THAN
LAST YEAR AND PREVIOUS YEARS...SO EVEN THOUGH WAVES WILL NOT BE
QUITE AS HIGH AS SANDY A FEW YEARS AGO...THE LAKE SHORE FLOODING
IMPACT COULD BE SIMILAR. HAVE GONE AHEAD AND ISSUED A LAKESHORE
FLOOD ADVISORY TO HIGHLIGHT THE LIKELY COASTAL INUNDATION IMPACT
FROM THE LARGE AND BATTERING WAVES.

COULD SEE SOME SHOWERS ALONG THE COLD FRONT TONIGHT...BUT FRONT
SHOULD CLEAR THE AREA BY FRIDAY MORNING WITH SYNOPTIC PRECIP THREAT
LARGELY ENDING. HOWEVER...VERY IMPRESSIVE LAKE EFFECT SET-UP LOOKS
TO DEVELOP FRIDAY INTO FRIDAY EVENING WITH VERY HIGH LAKE INDUCED
EQUILIBRIUM LEVELS UP TO AROUND 20KFT AND UP TO NEARLY -30C. GIVEN
THE LIKELY PRESENCE OF SUPER COOLED LIQUID IN THE CLOUDS AND HIGH
EQUILIBRIUM LEVELS IT SEEMS QUITE LIKELY THAT ISOLATED THUNDERSTORMS
WILL OCCUR IN ADDITION TO FAIRLY WIDESPREAD SHOWERS FRIDAY. THESE
EARLY SEASON LAKE EFFECT EVENTS ARE ALWAYS TRICKY WITH P-TYPE AS THE
VERY COLD AIR ALOFT...AROUND -8 TO -10C AT 850MB WOULD SOLIDLY
SUPPORT SNOW DESPITE WARM WATER TEMPS IN THE 50S STILL. HAVE GONE
WITH RAIN OR SNOW SHOWERS FOR NOW...BUT THINK THE FARTHER INLAND
AWAY FROM THE LAKE YOU GET THE BETTER CHANCE WILL BE FOR ALL SNOW
SHOWERS FRIDAY AFTERNOON AND EVENING INTO NW INDIANA. GIVEN THE
POTENTIAL FOR THUNDERSTORMS AND ADDED DYNAMIC COOLING AM CONCERNED
THAT SOME PORTIONS OF NW INDIANA...ESPECIALLY A BIT INLAND FROM THE
LAKE...COULD END UP WITH A SLUSHY COUPLE INCHES OF SNOW ACCUMULATION
ON GRASSY SURFACES BY FRIDAY EVENING...THOUGH CONFIDENCE IS TOO LOW
TO HIT THAT TOO HARD AT THIS TIME. LOW LEVEL FLOW SHOULD SLOWLY VEER
SO THAT THE FOCUS FOR LAKE EFFECT PRECIP SHOULD START IN PORTER
COUNTY EARLY FRIDAY AND GRADUALLY SHIFT WEST INTO LAKE COUNTY
INDIANA FRIDAY AFTERNOON AND POTENTIALLY INTO SOUTHEAST COOK COUNTY
FRIDAY EVENING BEFORE INVERSION HEIGHTS CRASH AND LAKE EFFECT WINDS
DOWN LATE FRIDAY NIGHT.

THE COMBINATION OF STRONG WINDS AND UNSEASONABLY COLD TEMPS WILL
SEND WIND CHILLS DROPPING INTO THE 20S DURING TRICK OR TREATING
HOURS FRIDAY EVENING...WITH EVEN LESS FAVORABLE TRICK OR TREATING
WEATHER IN NW INDIANA UNDER THE LAKE EFFECT RAIN/SNOW SHOWERS. AFTER
THE UNSEASONABLY COLD TEMPERATURES AND WIND CHILLS FRIDAY INTO
FRIDAY NIGHT...LOOK FOR QUIET CONDITIONS OVER THE WEEKEND WITH VERY
SLOWLY MODERATING TEMPERATURES. PROGRESSIVE PATTERN SHOULD RESULT IN
TRANSIENT RIDGE MOVING EAST OF THE AREA EARLY NEXT WEEK WITH NEXT
SYSTEM BRINGING THE POTENTIAL FOR SHOWERS MONDAY NIGHT INTO TUESDAY.
TEMPERATURES SHOULD BE CLOSER TO SEASONAL NORMAL NEXT WEEK RETURNING
TO WHAT WILL FEEL LIKE THE RATHER PLEASANT 50S FOLLOWING FRIDAY`S
FLIRTATION WITH WINTER-LIKE TEMPERATURES.

IZZI

&&

.AVIATION...

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

* TIMING OF COLD FRONT PASSAGE WITH WIND SHIFT TO NWLY...GUSTS TO
  30KT AND CIGS LOWERING TO MVFR AND CHANCE SHRA.

KREIN

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

THE REMAINDER OF THE NIGHT AND THROUGH MUCH DAY THURSDAY...
CONDITIONS WILL BE QUIET AT THE TERMINALS. THE STRATOCU DECK HAS
PUSHED WELL TO THE EAST...LEAVING MOSTLY CLEAR SKIES TO START THE
PERIOD. LATEST SATELLITE IMAGERY SHOWS AN AREA OF MID AND HIGH
CLOUD CROSSING THE UPPER MISSISSIPPI VALLEY ASSOCIATED WITH A MID
LEVEL IMPULSE...WHICH WILL OVERSPREAD THE TERMINALS FOR THE
REMAINDER OF THE OVERNIGHT HOURS. WITH SFC HIGH PRESSURE CENTERED
OVER NRN IL...WINDS WILL BE LIGHT AND VARIABLE FOR THE REMAINDER
OF THE NIGHT AND INTO TOMORROW MORNING. AS THE HIGH SLIDES OFF TO
THE SOUTHEAST...WINDS SHOULD BECOME MORE SWLY-WLY THROUGH THE
DAY AND INTO THE EVENING...WITH SPEEDS REMAINING LESS THAN 10KT.

AN ABRUPT CHANCE IS EXPECTED LATE TOMORROW NIGHT AS A STRONG COLD
FRONT PUSHES SOUTH ACROSS THE AREA. THE LATEST GUIDANCE SUGGESTS
THAT THE FRONT WILL PUSH THROUGH RFD BY ARND 04Z...AND THEN
QUICKLY PUSHING SOUTH THROUGH THE CHICAGO AREA TERMINALS BY
05-06Z. THIS WILL BE A VERY SHARP BOUNDARY AND WINDS SHOULD
QUICKLY SHIFT TO NWLY AND STRENGTHEN WITH GUSTS UP TO 30KT
FOLLOWING THE FROPA. THERE WILL ALSO BE A SHALLOW BAND OF MOISTURE
WITH THE FRONT...AND EXPECT THAT CIGS SHOULD QUICKLY DROP TO LOWER
END MVFR LEVELS. THERE IS A CHANCE FOR SOME SHRA FOLLOWING THE
FROPA FOR A BRIEF PERIOD...BUT HAVE LOW CONFIDENCE IN THE TIMING
AND COVERAGE OF PCPN...SO WILL LEAVE ANY MENTION OF PCPN OUT OF
THE TAFS FOR NOW AND RE-EVALUATE WITH LATER UPDATES.

KREIN

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

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS UP TO THE TIMING OF THE
  COLD FRONT PASSAGE THURSDAY NIGHT.

* HIGH CONFIDENCE IN THE IMPACTS OF THE FROPA ON TERMINAL
  CONDITIONS...BUT MEDIUM CONFIDENCE ON THE EXACT TIMING.

KREIN

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

* FRIDAY...STRONG NORTH WINDS GUSTING TO 35 KT. CHANCE OF SHRA OR
  SHSN.
* SATURDAY...DRY/VFR. NORTHEAST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...CHANCE OF SHRA. GUSTY SOUTHERLY WINDS.
* TUESDAY...CHANCE OF SHRA. WESTERLY WINDS.

&&

.MARINE...
319 AM CDT

SHARP UPPER TROUGH WILL DIG INTO THE WESTERN GREAT LAKES REGION
TONIGHT AND RESULT IN SURFACE LOW DEVELOPING AND SLOWLY INTENSIFYING
TONIGHT INTO FRIDAY OVER THE EASTERN LAKES. MEANWHILE...UPSTREAM
HIGH PRESSURE OVER THE CANADIAN PRAIRIES WILL STRENGTHEN AS IT MOVES
SOUTHEAST INTO THE NORTHERN PLAINS TONIGHT INTO FRIDAY. THE RESULT
WILL BE A VERY TIGHT PRESSURE GRADIENT DEVELOPING OVER THE AREA
LATER TONIGHT INTO FRIDAY AND WHEN COMBINED WITH THE EXTREME
INSTABILITY LIKELY TO DEVELOP AS A RESULT OF THE VERY COLD AIR ALOFT
MOVING IN...AM EXPECTING A PERIOD OF HIGH END GALES TO LOW END STORM
FORCE WINDS OVER THE LAKE LATE TONIGHT THROUGH FRIDAY NIGHT. CURRENT
INDICATIONS ARE THAT THE LONGEST DURATION AND HIGHEST PROBABILITY OF
STORM FORCE WINDS WILL EXIST OVER SOUTHERN LAKE MICHIGAN AND HAVE
OPTED TO UPGRADE TO A STORM WARNING THERE FOR FRIDAY...INCLUDING THE
NORTHWEST INDIANA NEARSHORE WATERS UP TO NORTHERLY ISLAND IN THE
ILLINOIS NEARSHORE. THE NORTHERN PORTIONS OF THE ILLINOIS NEARSHORE
MAY END UP WITH A MORE OFFSHORE FETCH IN THE 350-360 RANGE LESSENING
THE THREAT OF STORM FORCE WINDS A BIT. NORTHERN PORTIONS OF THE LAKE
COULD SEE STORM FORCE GUSTS FOR A TIME FRIDAY MORNING BUT DURATION
LOOKS TO BE LESS AND CONFIDENCE LOWER...SO JUST HINTED AT THIS
THREAT IN THE GLF. FULL FETCH NORTH STORM FORCE WINDS SHOULD HAVE NO
PROBLEM KICKING WAVES UP TO AROUND OR JUST ABOVE 20 FT OVER SOUTHERN
PORTIONS OF THE LAKE FRIDAY AFTERNOON AND EVENING. WINDS SHOULD
SUBSIDE RATHER QUICKLY FRIDAY NIGHT INTO SATURDAY AS THE PATTERN
REMAINS PROGRESSIVE AND THE HIGH PRESSURE RESPONSIBLE FOR THE STORM
EVENT MOVES INTO THE WESTERN LAKES REGION ALLOWING WINDS AND
EVENTUALLY WAVES TO SUBSIDE SATURDAY. LATER SUNDAY INTO EARLY NEXT
WEEK 25-30KT SOUTHERLY WINDS COULD DEVELOP AS HIGH PUSHES OFF TO THE
EAST AND NEW LOW PRESSURE DEVELOPS OVER THE NORTHERN PLAINS.

IZZI

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
     LMZ868...1 AM FRIDAY TO 10 PM FRIDAY.

     GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-
     LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-
     LMZ874-LMZ876-LMZ878...4 AM FRIDAY TO 4 AM SATURDAY.

&&

$$

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

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






000
FXUS63 KILX 300832
AFDILX

Area Forecast Discussion
NATIONAL WEATHER SERVICE LINCOLN IL
332 AM CDT Thu Oct 30 2014

.SHORT TERM...(Today)
ISSUED AT 331 AM CDT THU OCT 30 2014

High pressure centered over the area will slowly drift east today
and give way to a weather system approaching from the west. This low
pressure area will move east and then southeast while another low
pressure area moves across the Great Lakes region. Both of these are
associated with an upper level trough that will be moving through
the area today. These features will not have a lot of moisture to
work with, but will bring a chance of showers to the CWA today. Pops
will be only in the chance category and not expecting any
thunderstorms at this time. Light winds this morning will become
southeast, and then easterly during the afternoon. Wind speeds
should be around 5 to 10 mph.

MOS guidance looks ok, but MAV looks a little warm in the southeast
given the expected cloud cover and chance of pcpn. So, mid to upper
50s looks reasonable for today.

&&

.LONG TERM...(Tonight through Thursday)
ISSUED AT 331 AM CDT THU OCT 30 2014

An extended period of below normal temperatures is still expected
across central and southeast Illinois into next week. The coldest
period will extend from Friday to Sunday, with a hard freeze likely
early Saturday and Sunday mornings. A bit too early for a Freeze
Watch being 4th and 6th periods, but will issue a special weather
statement to address the the freezing conditions that will likely
end the growning season. This will be the first hard freeze across
the forecast area and running about two weeks later than normal.
Halloween Trick or Treat conditions will be less than ideal with
actual temperatures in the upper 30s or lower 40s and wind chill
values in the upper 20s and lower 30s late friday afternoon into
early Friday evening with blustery north winds gusting to around
35 mph at times Friday afternoon.

The short wave that tracks across MO and sw IL by sunset, and into
the mid MS river valley by midnight tonight, and into western KY/TN
by dawn Fri, will linger chances of rain showers especially over
southeast IL. A much stronger northern stream short wave, currently
diving into Saskatchewan and Manitoba, will track across the Great
Lakes/Midwest on Friday. Most of the moisture will be east of IL
Friday and Friday night and just have small chances of light rain
showers in far eastern IL Friday and then mixes with or changes to
light snow by Friday evening over IN. However, this system will be
accompanied by gusty north winds of 20-25 mph and gusts of 25 to 40
mph and will help usher in the airmass that will provide our hard
freeze for Friday and Saturday nights with lows 25-30F both nights.

Upper level ridging will shift eastward into IL late in the weekend
into early next week with temperatures modifying Mon-Wed with highs
in the mid 50s to lower 60s. The ridge will shift east of IL later
Monday into Tue while strong upper level low/trof digs into the
southern Rockies. This puts IL in an unsettled upper level sw flow
and increasing chances of showers Mon-Tue night as a frontal system
sets up from the southern plains ne into the ohio river valley.
Isolated thunderstorms may also occur Monday night and Tue south of
I-72. Best rain chances will shift se into the Ohio river valley Wed
and lingered 20-30% chances of showers over southeast IL. Drier
weather expected Wed night and Thu with highs still in the 50s on
Thu.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
ISSUED AT 1059 PM CDT WED OCT 29 2014

High pressure centered over Illinois late this evening will drift
off to our east overnight allowing a light southerly flow to develop
across the west. As the high shifts away from our area, mid and high
level clouds, now over central Iowa, will streak into central Illinois
after 08z. Forecast soundings and time height cross sections indicate
a gradual lowering and thickening of the clouds during the day Thursday
as a weather disturbance tracks across the region. A band of showers
will develop to the north of a weak storm system forecast to shift
well south of our area during the afternoon and evening hours.

Soundings continue to indicate low VFR cigs across the area Thursday
night before a secondary wave drops southeast into the lower Great
Lakes and deepens in over the region producing MVFR or lower cigs
after 06z Friday along with strong northerly winds. Surface winds
tonight will gradually become southerly but continue to be on the
light side and then become southeast to east during the day on
Thursday with speeds in the 5 to 10 kt range.

&&

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

&&

$$

SHORT TERM...Auten
LONG TERM...07
AVIATION...Smith







000
FXUS63 KLOT 300819
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
319 AM CDT THU OCT 30 2014

.SHORT TERM...

FORTHCOMING...

IZZI

&&

.LONG TERM...
308 AM CDT

STRONG UPPER TROUGH/CLOSED LOW WILL CONTINUE TO DIG SOUTH THROUGH
THE WESTERN LAKES REGION FRIDAY. STRONG COLD AIR ADVECTION AND
TIGHTENING PRESSURE GRADIENT BETWEEN DEVELOPING SFC LOW TO OUR EAST
AND STRENGTHENING SFC HIGH APPROACHING FROM THE NORTHWEST WILL
RESULT IN STRONG NORTHERLY WINDS FRIDAY...ESPECIALLY NEAR THE LAKE.
FORECAST SOUNDINGS SUPPORT GUSTS TO AROUND 40 MPH MOST AREAS
FRIDAY...THOUGH THE LESSER FRICTION AND STRONGER INSTABILITY AND
RESULTANT MIXING NEAR THE LAKE SHOULD SUPPORT WIND GUSTS OF 50+ MPH
NEAR THE LAKE...ESPECIALLY COOK COUNTY AND NW INDIANA SHORE. COULD
BE A MARGINAL HIGH WIND WARNING FOR LAKE SHORE AREAS WITH A SOLID
WIND ADVISORY EVENT LIKELY. GIVEN THE UNCERTAINTY OPTED TO HOLD OFF
ON HEADLINES FOR NOW AND WILL LET LATER SHIFTS DECIDE.

THE FULL FETCH STORM FORCE WINDS WILL RESULT IN 20FT+
WAVES...PARTICULARLY FOR COOK COUNTY INTO NW INDIANA GIVEN THE
350-360 WIND DIRECTION. LAKE LEVELS ARE NEARLY 2 FEET HIGHER THAN
LAST YEAR AND PREVIOUS YEARS...SO EVEN THOUGH WAVES WILL NOT BE
QUITE AS HIGH AS SANDY A FEW YEARS AGO...THE LAKE SHORE FLOODING
IMPACT COULD BE SIMILAR. HAVE GONE AHEAD AND ISSUED A LAKESHORE
FLOOD ADVISORY TO HIGHLIGHT THE LIKELY COASTAL INUNDATION IMPACT
FROM THE LARGE AND BATTERING WAVES.

COULD SEE SOME SHOWERS ALONG THE COLD FRONT TONIGHT...BUT FRONT
SHOULD CLEAR THE AREA BY FRIDAY MORNING WITH SYNOPTIC PRECIP THREAT
LARGELY ENDING. HOWEVER...VERY IMPRESSIVE LAKE EFFECT SET-UP LOOKS
TO DEVELOP FRIDAY INTO FRIDAY EVENING WITH VERY HIGH LAKE INDUCED
EQUILIBRIUM LEVELS UP TO AROUND 20KFT AND UP TO NEARLY -30C. GIVEN
THE LIKELY PRESENCE OF SUPER COOLED LIQUID IN THE CLOUDS AND HIGH
EQUILIBRIUM LEVELS IT SEEMS QUITE LIKELY THAT ISOLATED THUNDERSTORMS
WILL OCCUR IN ADDITION TO FAIRLY WIDESPREAD SHOWERS FRIDAY. THESE
EARLY SEASON LAKE EFFECT EVENTS ARE ALWAYS TRICKY WITH P-TYPE AS THE
VERY COLD AIR ALOFT...AROUND -8 TO -10C AT 850MB WOULD SOLIDLY
SUPPORT SNOW DESPITE WARM WATER TEMPS IN THE 50S STILL. HAVE GONE
WITH RAIN OR SNOW SHOWERS FOR NOW...BUT THINK THE FARTHER INLAND
AWAY FROM THE LAKE YOU GET THE BETTER CHANCE WILL BE FOR ALL SNOW
SHOWERS FRIDAY AFTERNOON AND EVENING INTO NW INDIANA. GIVEN THE
POTENTIAL FOR THUNDERSTORMS AND ADDED DYNAMIC COOLING AM CONCERNED
THAT SOME PORTIONS OF NW INDIANA...ESPECIALLY A BIT INLAND FROM THE
LAKE...COULD END UP WITH A SLUSHY COUPLE INCHES OF SNOW ACCUMULATION
ON GRASSY SURFACES BY FRIDAY EVENING...THOUGH CONFIDENCE IS TOO LOW
TO HIT THAT TOO HARD AT THIS TIME. LOW LEVEL FLOW SHOULD SLOWLY VEER
SO THAT THE FOCUS FOR LAKE EFFECT PRECIP SHOULD START IN PORTER
COUNTY EARLY FRIDAY AND GRADUALLY SHIFT WEST INTO LAKE COUNTY
INDIANA FRIDAY AFTERNOON AND POTENTIALLY INTO SOUTHEAST COOK COUNTY
FRIDAY EVENING BEFORE INVERSION HEIGHTS CRASH AND LAKE EFFECT WINDS
DOWN LATE FRIDAY NIGHT.

THE COMBINATION OF STRONG WINDS AND UNSEASONABLY COLD TEMPS WILL
SEND WIND CHILLS DROPPING INTO THE 20S DURING TRICK OR TREATING
HOURS FRIDAY EVENING...WITH EVEN LESS FAVORABLE TRICK OR TREATING
WEATHER IN NW INDIANA UNDER THE LAKE EFFECT RAIN/SNOW SHOWERS. AFTER
THE UNSEASONABLY COLD TEMPERATURES AND WIND CHILLS FRIDAY INTO
FRIDAY NIGHT...LOOK FOR QUIET CONDITIONS OVER THE WEEKEND WITH VERY
SLOWLY MODERATING TEMPERATURES. PROGRESSIVE PATTERN SHOULD RESULT IN
TRANSIENT RIDGE MOVING EAST OF THE AREA EARLY NEXT WEEK WITH NEXT
SYSTEM BRINGING THE POTENTIAL FOR SHOWERS MONDAY NIGHT INTO TUESDAY.
TEMPERATURES SHOULD BE CLOSER TO SEASONAL NORMAL NEXT WEEK RETURNING
TO WHAT WILL FEEL LIKE THE RATHER PLEASANT 50S FOLLOWING FRIDAY`S
FLIRTATION WITH WINTER-LIKE TEMPERATURES.

IZZI

&&

.AVIATION...

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

* TIMING OF COLD FRONT PASSAGE WITH WIND SHIFT TO NWLY...GUSTS TO
  30KT AND CIGS LOWERING TO MVFR AND CHANCE SHRA.

KREIN

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

THE REMAINDER OF THE NIGHT AND THROUGH MUCH DAY THURSDAY...
CONDITIONS WILL BE QUIET AT THE TERMINALS. THE STRATOCU DECK HAS
PUSHED WELL TO THE EAST...LEAVING MOSTLY CLEAR SKIES TO START THE
PERIOD. LATEST SATELLITE IMAGERY SHOWS AN AREA OF MID AND HIGH
CLOUD CROSSING THE UPPER MISSISSIPPI VALLEY ASSOCIATED WITH A MID
LEVEL IMPULSE...WHICH WILL OVERSPREAD THE TERMINALS FOR THE
REMAINDER OF THE OVERNIGHT HOURS. WITH SFC HIGH PRESSURE CENTERED
OVER NRN IL...WINDS WILL BE LIGHT AND VARIABLE FOR THE REMAINDER
OF THE NIGHT AND INTO TOMORROW MORNING. AS THE HIGH SLIDES OFF TO
THE SOUTHEAST...WINDS SHOULD BECOME MORE SWLY-WLY THROUGH THE
DAY AND INTO THE EVENING...WITH SPEEDS REMAINING LESS THAN 10KT.

AN ABRUPT CHANCE IS EXPECTED LATE TOMORROW NIGHT AS A STRONG COLD
FRONT PUSHES SOUTH ACROSS THE AREA. THE LATEST GUIDANCE SUGGESTS
THAT THE FRONT WILL PUSH THROUGH RFD BY ARND 04Z...AND THEN
QUICKLY PUSHING SOUTH THROUGH THE CHICAGO AREA TERMINALS BY
05-06Z. THIS WILL BE A VERY SHARP BOUNDARY AND WINDS SHOULD
QUICKLY SHIFT TO NWLY AND STRENGTHEN WITH GUSTS UP TO 30KT
FOLLOWING THE FROPA. THERE WILL ALSO BE A SHALLOW BAND OF MOISTURE
WITH THE FRONT...AND EXPECT THAT CIGS SHOULD QUICKLY DROP TO LOWER
END MVFR LEVELS. THERE IS A CHANCE FOR SOME SHRA FOLLOWING THE
FROPA FOR A BRIEF PERIOD...BUT HAVE LOW CONFIDENCE IN THE TIMING
AND COVERAGE OF PCPN...SO WILL LEAVE ANY MENTION OF PCPN OUT OF
THE TAFS FOR NOW AND RE-EVALUATE WITH LATER UPDATES.

KREIN

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

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS UP TO THE TIMING OF THE
  COLD FRONT PASSAGE THURSDAY NIGHT.

* HIGH CONFIDENCE IN THE IMPACTS OF THE FROPA ON TERMINAL
  CONDITIONS...BUT MEDIUM CONFIDENCE ON THE EXACT TIMING.

KREIN

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

* FRIDAY...STRONG NORTH WINDS GUSTING TO 35 KT. CHANCE OF SHRA OR
  SHSN.
* SATURDAY...DRY/VFR. NORTHEAST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...CHANCE OF SHRA. GUSTY SOUTHERLY WINDS.
* TUESDAY...CHANCE OF SHRA. WESTERLY WINDS.

&&

.MARINE...
319 AM CDT

SHARP UPPER TROUGH WILL DIG INTO THE WESTERN GREAT LAKES REGION
TONIGHT AND RESULT IN SURFACE LOW DEVELOPING AND SLOWLY INTENSIFYING
TONIGHT INTO FRIDAY OVER THE EASTERN LAKES. MEANWHILE...UPSTREAM
HIGH PRESSURE OVER THE CANADIAN PRAIRIES WILL STRENGTHEN AS IT MOVES
SOUTHEAST INTO THE NORTHERN PLAINS TONIGHT INTO FRIDAY. THE RESULT
WILL BE A VERY TIGHT PRESSURE GRADIENT DEVELOPING OVER THE AREA
LATER TONIGHT INTO FRIDAY AND WHEN COMBINED WITH THE EXTREME
INSTABILITY LIKELY TO DEVELOP AS A RESULT OF THE VERY COLD AIR ALOFT
MOVING IN...AM EXPECTING A PERIOD OF HIGH END GALES TO LOW END STORM
FORCE WINDS OVER THE LAKE LATE TONIGHT THROUGH FRIDAY NIGHT. CURRENT
INDICATIONS ARE THAT THE LONGEST DURATION AND HIGHEST PROBABILITY OF
STORM FORCE WINDS WILL EXIST OVER SOUTHERN LAKE MICHIGAN AND HAVE
OPTED TO UPGRADE TO A STORM WARNING THERE FOR FRIDAY...INCLUDING THE
NORTHWEST INDIANA NEARSHORE WATERS UP TO NORTHERLY ISLAND IN THE
ILLINOIS NEARSHORE. THE NORTHERN PORTIONS OF THE ILLINOIS NEARSHORE
MAY END UP WITH A MORE OFFSHORE FETCH IN THE 350-360 RANGE LESSENING
THE THREAT OF STORM FORCE WINDS A BIT. NORTHERN PORTIONS OF THE LAKE
COULD SEE STORM FORCE GUSTS FOR A TIME FRIDAY MORNING BUT DURATION
LOOKS TO BE LESS AND CONFIDENCE LOWER...SO JUST HINTED AT THIS
THREAT IN THE GLF. FULL FETCH NORTH STORM FORCE WINDS SHOULD HAVE NO
PROBLEM KICKING WAVES UP TO AROUND OR JUST ABOVE 20 FT OVER SOUTHERN
PORTIONS OF THE LAKE FRIDAY AFTERNOON AND EVENING. WINDS SHOULD
SUBSIDE RATHER QUICKLY FRIDAY NIGHT INTO SATURDAY AS THE PATTERN
REMAINS PROGRESSIVE AND THE HIGH PRESSURE RESPONSIBLE FOR THE STORM
EVENT MOVES INTO THE WESTERN LAKES REGION ALLOWING WINDS AND
EVENTUALLY WAVES TO SUBSIDE SATURDAY. LATER SUNDAY INTO EARLY NEXT
WEEK 25-30KT SOUTHERLY WINDS COULD DEVELOP AS HIGH PUSHES OFF TO THE
EAST AND NEW LOW PRESSURE DEVELOPS OVER THE NORTHERN PLAINS.

IZZI

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ742-LMZ743-
     LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-LMZ876-
     LMZ878...7 PM FRIDAY TO 4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ742-LMZ743-
     LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-LMZ876-
     LMZ878...6 AM FRIDAY TO 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
     LMZ868...1 AM FRIDAY TO 10 PM FRIDAY.

     GALE WARNING...LMZ740-LMZ741...6 AM FRIDAY TO 4 AM SATURDAY.

&&

$$

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

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






000
FXUS63 KLOT 300809
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
309 AM CDT THU OCT 30 2014

.SHORT TERM...(THROUGH TONIGHT)

FORTHCOMING...

IZZI

&&

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
308 AM CDT

STRONG UPPER TROUGH/CLOSED LOW WILL CONTINUE TO DIG SOUTH THROUGH
THE WESTERN LAKES REGION FRIDAY. STRONG COLD AIR ADVECTION AND
TIGHTENING PRESSURE GRADIENT BETWEEN DEVELOPING SFC LOW TO OUR EAST
AND STRENGTHENING SFC HIGH APPROACHING FROM THE NORTHWEST WILL
RESULT IN STRONG NORTHERLY WINDS FRIDAY...ESPECIALLY NEAR THE LAKE.
FORECAST SOUNDINGS SUPPORT GUSTS TO AROUND 40 MPH MOST AREAS
FRIDAY...THOUGH THE LESSER FRICTION AND STRONGER INSTABILITY AND
RESULTANT MIXING NEAR THE LAKE SHOULD SUPPORT WIND GUSTS OF 50+ MPH
NEAR THE LAKE...ESPECIALLY COOK COUNTY AND NW INDIANA SHORE. COULD
BE A MARGINAL HIGH WIND WARNING FOR LAKE SHORE AREAS WITH A SOLID
WIND ADVISORY EVENT LIKELY. GIVEN THE UNCERTAINTY OPTED TO HOLD OFF
ON HEADLINES FOR NOW AND WILL LET LATER SHIFTS DECIDE.

THE FULL FETCH STORM FORCE WINDS WILL RESULT IN 20FT+
WAVES...PARTICULARLY FOR COOK COUNTY INTO NW INDIANA GIVEN THE
350-360 WIND DIRECTION. LAKE LEVELS ARE NEARLY 2 FEET HIGHER THAN
LAST YEAR AND PREVIOUS YEARS...SO EVEN THOUGH WAVES WILL NOT BE
QUITE AS HIGH AS SANDY A FEW YEARS AGO...THE LAKE SHORE FLOODING
IMPACT COULD BE SIMILAR. HAVE GONE AHEAD AND ISSUED A LAKESHORE
FLOOD ADVISORY TO HIGHLIGHT THE LIKELY COASTAL INUNDATION IMPACT
FROM THE LARGE AND BATTERING WAVES.

COULD SEE SOME SHOWERS ALONG THE COLD FRONT TONIGHT...BUT FRONT
SHOULD CLEAR THE AREA BY FRIDAY MORNING WITH SYNOPTIC PRECIP THREAT
LARGELY ENDING. HOWEVER...VERY IMPRESSIVE LAKE EFFECT SET-UP LOOKS
TO DEVELOP FRIDAY INTO FRIDAY EVENING WITH VERY HIGH LAKE INDUCED
EQUILIBRIUM LEVELS UP TO AROUND 20KFT AND UP TO NEARLY -30C. GIVEN
THE LIKELY PRESENCE OF SUPER COOLED LIQUID IN THE CLOUDS AND HIGH
EQUILIBRIUM LEVELS IT SEEMS QUITE LIKELY THAT ISOLATED THUNDERSTORMS
WILL OCCUR IN ADDITION TO FAIRLY WIDESPREAD SHOWERS FRIDAY. THESE
EARLY SEASON LAKE EFFECT EVENTS ARE ALWAYS TRICKY WITH P-TYPE AS THE
VERY COLD AIR ALOFT...AROUND -8 TO -10C AT 850MB WOULD SOLIDLY
SUPPORT SNOW DESPITE WARM WATER TEMPS IN THE 50S STILL. HAVE GONE
WITH RAIN OR SNOW SHOWERS FOR NOW...BUT THINK THE FARTHER INLAND
AWAY FROM THE LAKE YOU GET THE BETTER CHANCE WILL BE FOR ALL SNOW
SHOWERS FRIDAY AFTERNOON AND EVENING INTO NW INDIANA. GIVEN THE
POTENTIAL FOR THUNDERSTORMS AND ADDED DYNAMIC COOLING AM CONCERNED
THAT SOME PORTIONS OF NW INDIANA...ESPECIALLY A BIT INLAND FROM THE
LAKE...COULD END UP WITH A SLUSHY COUPLE INCHES OF SNOW ACCUMULATION
ON GRASSY SURFACES BY FRIDAY EVENING...THOUGH CONFIDENCE IS TOO LOW
TO HIT THAT TOO HARD AT THIS TIME. LOW LEVEL FLOW SHOULD SLOWLY VEER
SO THAT THE FOCUS FOR LAKE EFFECT PRECIP SHOULD START IN PORTER
COUNTY EARLY FRIDAY AND GRADUALLY SHIFT WEST INTO LAKE COUNTY
INDIANA FRIDAY AFTERNOON AND POTENTIALLY INTO SOUTHEAST COOK COUNTY
FRIDAY EVENING BEFORE INVERSION HEIGHTS CRASH AND LAKE EFFECT WINDS
DOWN LATE FRIDAY NIGHT.

THE COMBINATION OF STRONG WINDS AND UNSEASONABLY COLD TEMPS WILL
SEND WIND CHILLS DROPPING INTO THE 20S DURING TRICK OR TREATING
HOURS FRIDAY EVENING...WITH EVEN LESS FAVORABLE TRICK OR TREATING
WEATHER IN NW INDIANA UNDER THE LAKE EFFECT RAIN/SNOW SHOWERS. AFTER
THE UNSEASONABLY COLD TEMPERATURES AND WIND CHILLS FRIDAY INTO
FRIDAY NIGHT...LOOK FOR QUIET CONDITIONS OVER THE WEEKEND WITH VERY
SLOWLY MODERATING TEMPERATURES. PROGRESSIVE PATTERN SHOULD RESULT IN
TRANSIENT RIDGE MOVING EAST OF THE AREA EARLY NEXT WEEK WITH NEXT
SYSTEM BRINGING THE POTENTIAL FOR SHOWERS MONDAY NIGHT INTO TUESDAY.
TEMPERATURES SHOULD BE CLOSER TO SEASONAL NORMAL NEXT WEEK RETURNING
TO WHAT WILL FEEL LIKE THE RATHER PLEASANT 50S FOLLOWING FRIDAY`S
FLIRTATION WITH WINTER-LIKE TEMPERATURES.

IZZI

&&

.AVIATION...

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

* TIMING OF COLD FRONT PASSAGE WITH WIND SHIFT TO NWLY...GUSTS TO
  30KT AND CIGS LOWERING TO MVFR AND CHANCE SHRA.

KREIN

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

THE REMAINDER OF THE NIGHT AND THROUGH MUCH DAY THURSDAY...
CONDITIONS WILL BE QUIET AT THE TERMINALS. THE STRATOCU DECK HAS
PUSHED WELL TO THE EAST...LEAVING MOSTLY CLEAR SKIES TO START THE
PERIOD. LATEST SATELLITE IMAGERY SHOWS AN AREA OF MID AND HIGH
CLOUD CROSSING THE UPPER MISSISSIPPI VALLEY ASSOCIATED WITH A MID
LEVEL IMPULSE...WHICH WILL OVERSPREAD THE TERMINALS FOR THE
REMAINDER OF THE OVERNIGHT HOURS. WITH SFC HIGH PRESSURE CENTERED
OVER NRN IL...WINDS WILL BE LIGHT AND VARIABLE FOR THE REMAINDER
OF THE NIGHT AND INTO TOMORROW MORNING. AS THE HIGH SLIDES OFF TO
THE SOUTHEAST...WINDS SHOULD BECOME MORE SWLY-WLY THROUGH THE
DAY AND INTO THE EVENING...WITH SPEEDS REMAINING LESS THAN 10KT.

AN ABRUPT CHANCE IS EXPECTED LATE TOMORROW NIGHT AS A STRONG COLD
FRONT PUSHES SOUTH ACROSS THE AREA. THE LATEST GUIDANCE SUGGESTS
THAT THE FRONT WILL PUSH THROUGH RFD BY ARND 04Z...AND THEN
QUICKLY PUSHING SOUTH THROUGH THE CHICAGO AREA TERMINALS BY
05-06Z. THIS WILL BE A VERY SHARP BOUNDARY AND WINDS SHOULD
QUICKLY SHIFT TO NWLY AND STRENGTHEN WITH GUSTS UP TO 30KT
FOLLOWING THE FROPA. THERE WILL ALSO BE A SHALLOW BAND OF MOISTURE
WITH THE FRONT...AND EXPECT THAT CIGS SHOULD QUICKLY DROP TO LOWER
END MVFR LEVELS. THERE IS A CHANCE FOR SOME SHRA FOLLOWING THE
FROPA FOR A BRIEF PERIOD...BUT HAVE LOW CONFIDENCE IN THE TIMING
AND COVERAGE OF PCPN...SO WILL LEAVE ANY MENTION OF PCPN OUT OF
THE TAFS FOR NOW AND RE-EVALUATE WITH LATER UPDATES.

KREIN

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

* HIGH CONFIDENCE IN ALL FORECAST ELEMENTS UP TO THE TIMING OF THE
  COLD FRONT PASSAGE THURSDAY NIGHT.

* HIGH CONFIDENCE IN THE IMPACTS OF THE FROPA ON TERMINAL
  CONDITIONS...BUT MEDIUM CONFIDENCE ON THE EXACT TIMING.

KREIN

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

* FRIDAY...STRONG NORTH WINDS GUSTING TO 35 KT. CHANCE OF SHRA OR
  SHSN.
* SATURDAY...DRY/VFR. NORTHEAST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...CHANCE OF SHRA. GUSTY SOUTHERLY WINDS.
* TUESDAY...CHANCE OF SHRA. WESTERLY WINDS.

&&

.MARINE...
141 PM CDT

HIGH PRESSURE WILL MOVE ACROSS THE REGION TONIGHT RESULTING IN
EASING WINDS AND WAVES TONIGHT AND THURSDAY. SHARP UPPER TROUGH WILL
DIG INTO THE GREAT LAKES REGION THURSDAY NIGHT WITH SURFACE LOW
DEVELOPING OVER THE EASTERN GREAT LAKES. THE DEVELOPING LOW AND A
STRONG 1038MB HIGH OVER THE NORTHERN PLAINS WILL RESULT IN A
DRAMATIC INCREASE IN THE PRESSURE GRADIENT OVER THE LAKE LATE
THURSDAY NIGHT AND ESPECIALLY FRIDAY. IN ADDITION TO THE STRONG
GRADIENT...VERY COLD AIR MOVING OVER THE LAKE WILL PRODUCE STRONG TO
EXTREME INSTABILITY RESULTING IN DEEP AND EFFICIENT MIXING OF THE
HIGHER WINDS TO THE SURFACE. FORECAST SOUNDINGS SUGGEST THAT A
SEVERAL HOUR WINDOW OF STORM FORCE WINDS ARE POSSIBLE
FRIDAY...ESPECIALLY SOUTHERN PORTIONS OF THE LAKE...HOWEVER ENOUGH
MODEL UNCERTAINTY EXISTS TO HOLD OFF ON A STORM WATCH OR WARNING AT
THIS TIME BUT WILL ADD A FEW STORM FORCE GUSTS TO GLF AND GRIDS.
WINDS WILL SUBSIDE SATURDAY AND THEN BACK WITH FAIRLY STRONG
SOUTHERLY WINDS DEVELOPING LATE SUNDAY AND CONTINUING THROUGH
TUESDAY.

IZZI

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...LAKESHORE FLOOD ADVISORY...ILZ014...11 AM FRIDAY TO 4 AM
     SATURDAY.

IN...LAKESHORE FLOOD ADVISORY...INZ001-INZ002...11 AM FRIDAY TO 4 AM
     SATURDAY.

LM...GALE WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ742-LMZ743-
     LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-LMZ876-
     LMZ878...7 PM FRIDAY TO 4 AM SATURDAY.

     STORM WARNING...LMZ080-LMZ669-LMZ671-LMZ673-LMZ675-LMZ742-LMZ743-
     LMZ744-LMZ745-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-LMZ876-
     LMZ878...6 AM FRIDAY TO 7 PM FRIDAY.

     GALE WARNING...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
     LMZ868...1 AM FRIDAY TO 10 PM FRIDAY.

     GALE WARNING...LMZ740-LMZ741...6 AM FRIDAY TO 4 AM SATURDAY.

&&

$$

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

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