Area Forecast Discussion
Issued by NWS Chicago, IL

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000
FXUS63 KLOT 220811
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
311 AM CDT WED OCT 22 2014

.DISCUSSION...
310 AM CDT

TRANSITION AWAY FROM THE BELOW AVERAGE TEMPS OF LATE TO WARMER THAN
AVERAGE TEMPS BY THIS WEEKEND INTO EARLY NEXT WEEK STILL ON
TRACK...WITH A COUPLE SHOTS OF RAIN POSSIBLE.

ANY LINGERING LAKE CLOUDINESS IN NE IL EARLY THIS MORNING WILL FADE
WITH 100% SUNSHINE LOOKING LIKELY TODAY. TEMPERATURES SHOULD
MODERATE SEVERAL DEGREES OVER YESTERDAY MOST AREAS...THOUGH LAKE
ADJACENT AREAS OF NE IL WILL STILL FACE ONSHORE WINDS AND COOLER
TEMPS THAN THE REMAINDER OF THE CWA. MAINLY CLEAR SKIES AND LIGHT
WINDS SHOULD ALLOW FOR ANOTHER CHILLY NIGHT TONIGHT.

SKIES WILL CLOUD OVER THURSDAY LEAVING OUR PROSPECTS FOR SEEING THE
SOLAR ECLIPSE THURSDAY AFTERNOON DIM. SHARP UPPER TROUGH WILL
APPROACH FROM THE WEST THURSDAY AND DESPITE RELATIVE LACK OF
MOISTURE...FORCING LOOKS TO BE STRONG ENOUGH TO PROVIDE FOR A DECENT
SHOT OF SHOWERS SPREADING FROM WEST TO EAST THURSDAY AND ENDING
EASTERN CWA THURSDAY EVENING. SOUTHERN EXTENT OF THIS SHORTWAVE WILL
BE WEAKENING AS IT RUNS INTO THE NARROW RIDGE BEHIND THE LARGE
EASTERN CONUS UPPER LOW. THE ANTICIPATED GRADUAL WEAKENING OF THE
TROUGH IN OUR NECK OF THE WOODS IS REASONING FOR HIGHEST POPS WEST
AND LOWER POPS EAST...THOUGH GUIDANCE OFTEN WEAKENS THESE SYSTEMS
TOO QUICKLY AND HAVE GENERALLY GONE WITH HIGHER MOS POPS FOR THIS
SYSTEM.

WARM ADVECTION WILL RAMP UP BEHIND THIS SYSTEM AS UPPER RIDGING
BRIEFLY BUILDS INTO THE AREA FRIDAY ALLOWING FOR MODERATING TEMPS.
THE 00Z WRF-NAM DID HAVE A STRONGER TROUGH MOVING THROUGH ON FRIDAY
WITH SOME LIGHT QPF...BUT GIVEN THE GLOBAL MODELS ALL MUCH MORE
MUTED WITH THIS TROUGH WITH NO PRECIP HAVE BUMPED UP SKY COVER A BIT
AND POPS UP TO 10% BUT KEPT FORECAST DRY FOR NOW.

PATTERN WILL REMAIN QUITE AMPLIFIED THROUGH THE WEEKEND WITH DEEP
TROUGH TO OUR NE AND UPPER RIDGE BUILDING INTO THE CENTRAL CONUS.
GUIDANCE HAS TRENDED A BIT FARTHER WEST WITH THE NE CONUS UPPER
TROUGH THIS WEEKEND PLACING OUR CWA A BIT CLOSER TO THE COOLER AIR
MASS...BUT STILL EXPECT HIGHS TO MAKE IT INTO THE 60S. IT NOW
APPEARS THE GFS...ECMWF...AND GEM HAVE MONDAY AS OUR WARMEST DAY
WITH 850MB TEMPS PROGGED TO BE AROUND 1.5 STANDARD DEVIATIONS ABOVE
AVERAGE. GIVEN THE INCREASING SOUTHERLY WINDS THINK MOST OF THE CWA
STANDS A DECENT SHOT TO TAG 70F WITH ENSEMBLE MAX TEMPS AS WARM AS
THE MID TO UPPER 70S. COLD FRONT LOOKS TO END OUR BRIEF STINT OF
INDIAN SUMMER MONDAY NIGHT OR TUESDAY WITH SHOWERS AND POSSIBLY SOME
THUNDERSTORMS ACCOMPANYING THE FRONT.

IZZI

&&

.AVIATION...

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

* MVFR CIGS EARLY THIS MORNING.
* EAST WINDS MID MORNING THRU EARLY EVENING. CMS

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

HIGH PRESSURE WILL MOVE SOUTHEAST ACROSS THE REGION TODAY. LIGHT
EAST/NORTHEAST WINDS WILL SHIFT SOUTHEAST LATER THIS MORNING...
THEN TURN BACK EAST/NORTHEAST THIS AFTERNOON WITH A POSSIBLE LAKE
BREEZE. PREVAILING SPEEDS WILL LIKELY REMAIN UNDER 10KTS.

HIGH MVFR CIGS AROUND 3KFT WILL SLOWLY SCATTER OUT AND DISSIPATE
EARLY THIS MORNING WITH SKC EXPECTED LATER TODAY WITH INCREASING
HIGH CLOUDS TONIGHT. CMS

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

* MEDIUM FOR MVFR CIGS EARLY THIS MORNING.
* HIGH FOR WIND THRU THE PERIOD. CMS

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

* THURSDAY...CHANCE OF AFTERNOON SHRA. SOUTH WINDS.
* FRIDAY AND SATURDAY...DRY/VFR. WEST/SOUTHWEST WINDS.
* SUNDAY...DRY/VFR. SOUTH WINDS.
* MONDAY...SLIGHT CHANCE OF SHRA. GUSTY SOUTHWEST WINDS.

KJB

&&

.MARINE...

215 PM...LOW PRESSURE OVER WESTERN NEW YORK WILL MERGE WITH ANOTHER
LOW OVER NEAR THE DELMARVA AREA TONIGHT...AND RAPIDLY DEEPEN
WEDNESDAY NIGHT AND THURSDAY JUST SOUTH OF CAPE COD. THIS LOW WILL
THEN TRACK NORTHEAST TO NOVA SCOTIA BY SATURDAY MORNING.
MEANWHILE...HIGH PRESSURE CENTERED OVER THE SOUTHERN TIP OF JAMES
BAY...WITH HIGH PRESSURE RIDGING EXTENDING THROUGH THE MIDDLE
MISSISSIPPI VALLEY...WILL SLOWLY BUILD EAST. THE BRISK
NORTHEASTERLY WINDS CURRENTLY OVER THE LAKE WILL DIMINISH AND
BECOME LIGHT AND VARIABLE LATE TONIGHT AND EARLY WEDNESDAY AS THE
RIDGE AXIS CROSSES THE LAKE. WHILE WINDS SHOULD DROP BELOW SMALL
CRAFT ADVISORY LEVELS DURG THE AFTERNOON AND EARLY THIS
EVENING...RESIDUAL WAVE ACTION WILL BE SLOWER TO DAMPEN AND STILL
EXPECT THAT WAVES WILL REMAIN...ABOVE SMALL CRAFT ADVISORY LEVELS
THROUGH MUCH OF THE NIGHT. AS THE RIDGE MOVES TO THE EAST OF THE
LAKE WEDNESDAY NIGHT...A TROUGH OF LOW PRESSURE WILL CROSS THE
CENTRAL PLAINS...REACHING THE UPPER MISSISSIPPI VALLEY BY THURSDAY
MORNING. THIS WILL SET UP A STRENGTHENING SOUTHERLY GRADIENT OVER
THE LAKE WITH WINDS INCREASING TO ARND 20-25KT THURSDAY AFTERNOON.
WINDS WILL REMAIN SOUTHERLY UNTIL AN ASSOCIATED WEAK COLD FRONT
PUSHES ACROSS THE LAKE THURSDAY NIGHT.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 4 AM WEDNESDAY.

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 7 AM WEDNESDAY.

&&

$$

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