FXUS63 KLOT 100950
AFDLOT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
350 AM CST THU DEC 10 2009

.DISCUSSION...
333 AM CST

FOCUS OF FORECAST FOR TODAY AND FRI IS ON VERY COLD TEMPS AND
CORRESPONDING WIND CHILLS TODAY AND TONIGHT THEN MODERATION FRI AS
CORE OF COLD AIR MASS SHIFTS EASTWARD ACROSS THE GREAT LAKES WITH
CENTER OF LARGE HI PRES IN THE SOUTHERN PLAINS EARLY THIS MORNING
GRADUALLY MOVING E TO THE CENTRAL APPALACHIANS BY FRI NIGHT.

MODERATE WINDS TO CONTINUE TODAY BUT DUE TO CURRENT TEMPS OF ZERO
TO 3 BELOW AND ONLY SLOWLY CLIMBING DURING THE DAY WIND CHILL
VALUES TO BE IN 15 TO 25 BELOW RANGE TIL MIDDAY IN THE CURRENT
ADVISORY AREA. 

A FEW SHORT WAVES TO ROTATE THRU THE BROAD LONG WAVE TROF OVR NOAM
TODAY AND TONIGHT BUT WILL ONLY BRING OCNL MID AND HI CLOUDS AS
THEY APPROACH THE AREA WITH THE DRY AIR MASS IN PLACE.

NEXT CHANCE OF PCPN LOOKS TO BE OUT AT SAT NIGHT-SUN MORNING TIME
FRAME. BROAD UPPER TROF TO BE FLATTENING TODAY THRU SAT ALLOWING
THE STRONG SHORT WAVE CURRENTLY OVER THE PACIFIC AT AROUND 135W
MOVE ACROSS THE MID MS VALLEY AND INTO THE WESTERN GRTLKS SAT
NIGHT AND SUN. BY THEN SFC ANTICYCLONE TO BE CENTERED OVER THE MID
ATLANTIC COAST ALLOWING A RETURN FLOW OFF THE WESTERN GULF TO
REACH WELL NORTHWARD. ONLY HAVE SLIGHT CHC POPS AT THIS TIME AS
PLENTY OF ROOM FOR ERROR IN EVENTUAL TRACK OF THE SHORT WAVE AND
ASSOCIATED LOW LEVEL THERMAL AND MOISTURE PROFILES. IF PCPN DOES
OCCUR APPEARS WOULD BE A -SN EVENT FOLLOWED BY A PD OF -FZDZ
OVERNIGHT SAT INTO EARLY SUN MORNING AS SHALLOW MOIST LAYER
REMAINS IN PLACE AFTER SHORT WAVE TROF PASSES BY AND MID LEVELS DRY.

TRS

&&

.AVIATION...

06Z TAFS...FORECAST CONCERNS REMAIN LIGHT SNOW/BLOWING SNOW AND
ASSOCIATED VIS/CIGS...MAINLY THRU MORNING ALONG WITH WIND SPEEDS.

CIGS ALL OVER THE PLACE LATE THIS EVENING RANGING FROM LOW MVFR TO
VFR. BACK EDGE OF CLOUDS EXTENDS FROM NEAR DBQ TO UIN AND THIS
SHOULD MAKE STEADY PROGRESS EAST OVERNIGHT SO WILL MAINTAIN CIGS
SCATTERING OUT BY 12Z. BEFORE THEN...LIGHT SNOW FOR A FEW MORE HRS
WILL LIKELY ALLOW CIGS TO DIP INTO MVFR WITH VISIBILITIES RANGING
FROM 2-4SM...WHICH WILL ALSO BE AFFECTED BY BLOWING SNOW. THUS
HAVE MAINTAINED A TEMPO FOR A FEW HRS TO HANDLE THESE LOWER
CONDITIONS. HOWEVER...THE TREND WITH BOTH CIGS AND VIS SHOULD BE
UP THRU MORNING.

WIND SPEEDS/GUSTS LIKELY TO HOLD STEADY AT CURRENT READINGS WITH
GUSTS GENERALLY IN THE MID 20KT RANGE THRU MORNING AND THRU THE
DAY THURSDAY. COULD BE A FEW HIGHER GUSTS AT TIMES OVERNIGHT AND
PERHAPS A PERIOD UP NEAR 30KTS LATE THURSDAY MORNING. WIND GUSTS
EVENTUALLY DIMINISH WITH SUNSET THURSDAY AS WESTERLY WINDS TURN A
BIT MORE SOUTHWEST. CMS

&&

.MARINE...
347 AM CST

A LOW SOUTHWEST QUEBEC STILL HAS VERY LOW PRESSURE. THIS DEEP
LOW AND THE VERY COLD AND STRONG HIGH OVER THE CENTRAL PLAINS
WILL KEEP THE WEST WIND SPEED AT GALE TODAY AND TONIGHT. THE LOW
AIR TEMPERATURES OVER LAKE MICHIGAN MAY RESULT IN LIGHT FREEZING
SPRAY. THE LOW WILL MOVE TO THE GULF OF ST LAWRENCE BY FRIDAY
EVENING. THE HIGH WILL MOVE INTO TENNESSEE FRIDAY. THE PRESSURE
GRADIENT OVER THE LAKE WILL INCREASE FRIDAY SO WE WILL FORECAST AN
INCREASE IN WIND SPEED TO 40 KNOTS FRIDAY AFTERNOON. THE HIGH WILL
SETTLE IN EAST TENNESSEE FRIDAY NIGHT. THE PRESSURE GRADIENT OVER
LAKE MICHIGAN WILL DECREASE AND WE EXPECT THE WIND SPEED TO FALL
BELOW GALE FRIDAY NIGHT.

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WIND CHILL ADVISORY...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-ILZ011-
     ILZ012-ILZ019 UNTIL NOON THURSDAY.

IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
     LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
     LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL MIDNIGHT SATURDAY.

     GALE WARNING...NEARSHORE WATERS UNTIL 6 
     PM THURSDAY.

&&

$$