000 
FXUS63 KILX 122036 CCA
AFDILX

AREA FORECAST DISCUSSION...CORRECTION TO ADD COORDINATION CALLS
NATIONAL WEATHER SERVICE LINCOLN IL
230 PM CST WED FEB 12 2003

FORECAST CONCERNS EVOLVE AROUND THE LATE THURSDAY NIGHT AND FRIDAY
TIME FRAME FOR THE POTENTIAL FOR SOME SIGNIFICANT ICE ACCUMULATIONS 
OVER PARTS OF OUR FORECAST AREA. 

TONIGHT THROUGH SATURDAY NIGHT...

QUIET WEATHER TO HOLD ACRS CNTRL IL THROUGH MIDNIGHT THURSDAY...THEN
THINGS GET VERY INTERESTING FOR THE END OF THE WEEK. COLD HIGH 
PRESSURE CNTRD OVER SRN MO FCST BY MODELS TO SHIFT SLOWLY EAST OVER 
THE NEXT 24 HOURS. CLEAR SKIES AND LIGHT WINDS SHOULD ALLOW OVRNGT
TEMPERATURES TO REACH OR FALL BELOW GUID NUMBERS...ESPECIALLY ACRS
THE NORTH. SHOULD SEE SOME SUN ON FRIDAY WITH AN INCREASE IN HIGH 
CLOUDS DURING THE AFTERNOON AND EVENING. SWLY WINDS ON THE BACKSIDE
OF THE CANADIAN HIGH SHOULD PUSH THE AFTN HIGHS INTO THE MID 30S
FAR NORTH TO THE LOWER 40S FAR SE. 

MEANWHILE...THE PACIFIC STORM THAT HAS BEEN PRODUCING BENEFICIAL 
RAINS OVER THE WEST COAST WILL FINALLY MAKE ITS WAY INLAND LATER 
TONIGHT OR FRIDAY MORNING. SEVERAL LEAD SHORTWAVES HAVE EJECTED OUT 
OF THE MAIN UPPER LOW AND THOSE ARE CAUSING SOME FORECAST PROBLEMS 
WITH REGARDS TO PRECIP TIMING AND MAGNITUDE DURING THE LATE THURSDAY 
NIGHT AND FRIDAY TIME FRAME. DPROG/DT STILL INDICATING SOME 
DIFFERENCES IN TIMIN OF THE LEAD SHORTWAVES INTO THE MIDWEST THU 
NIGHT AND WITH THE MAIN UPPER LEVEL FEATURE ON FRIDAY. AVN HAS BEEN 
THE MOST CONSISTENT OVER THE PAST SVL RUNS SO WL LEAN MORE IN ITS 
DIRECTION. FREEZING RAIN WILL BREAKOUT IN AREAS WEST OF IL THURSDAY 
NIGHT AND SPREAD SLOWLY INTO OUR WRN COUNTIES AFTER MIDNIGHT...AND 
TO THE FAR NRN AND ERN COUNTIES BY THE FRIDAY MORNING RUSH HOUR. 
ONCE PRECIP STARTS...THE BIG QUESTION BECOMES HOW QUICKLY IT WILL 
CHANGE OVER TO LIQUID...IF EVER. MODEL FORECAST SOUNDINGS SUGGEST A 
TEMPORARY WARMING OF BNDRY LAYER AND SFC AFTER 18Z FRIDAY. 
HOWEVER...WITH A PREVAILING EASTERLY FLOW OFF ANOTHER LARGE COLD 
HIGH PRESSURE SYSTEM NORTH OF THE LAKES...AM HESITANT TO GET TOO 
AGGRESSIVE WITH THE CHANGEOVER ON FRIDAY...ESP ACRS THE NORTH. AVN 
INDICATING LOW LEVEL TEMPS BEGIN A SLOW DECLINE FRIDAY NIGHT INTO 
SATURDAY WHICH SHOULD CHANGE THE LIQUID OR FREEZING PRECIP OVER TO 
FROZEN PRECIP/SNOW. CHANCES FOR LIGHT SNOW CONTINUE INTO SAT NIGHT 
AS H5 TROF AND SFC LOW OVR TN SLOWLY PROGRESS ACRS THE MIDWEST.

THANKS TO DVN...LOT...LSX...EAX AND IND FOR THE COORD THIS AFTN.


DAYS 4-7...SUNDAY THROUGH WEDNESDAY.

00Z EXTENDED GFS DATA AND 12Z EURO MODEL IN AGREEMENT WITH PACIFIC 
ORIGIN SHORTWAVE MOVING THRU THE DAKOTAS LATE SAT...MOVING THRU THE 
UPR MIDWEST/MID-MISSISSIPPI RIVER VALLEY SUNDAY. THE WAVE WILL BE 
MOVING INTO A MOISTURE STARVED ATMOSPHERE...BUT SHLD BRING ENOUGH 
MOISTURE AND UPR LVL LIFT WITH IT FOR CHANCE OF LIGHT SNOW/FLURRIES. 
850H TEMPS VERIFY LAYER COLD ENOUGH FOR ONLY SNOW THREAT. BECAUSE 
THE MODELS ARE IN GOOD AGREEMENT WITH THIS FEATURE...WL ADD CHANCE 
OF SNOW SUNDAY.

SFC HIGH PRESSURE AND UPR RIDGING BUILD INTO REGION BY MON. SHLD SEE 
A FAIRLY COOL START TO THE DAY MON...BUT RETURN FLOW ON THE BACKSIDE 
OF THE HIGH SUGGEST A WARMING TREND LATER MON AND TUE. GFS SUGGESTS 
ANOTHER PACIFIC WAVE WILL MOVE INTO UPR MIDWEST DURING THE DAY TUE. 
WITH THE GIVEN TRACK...BEST UPR LVL SUPPORT REMAINS NORTH OF THE 
REGION. SFC HIGH ACRS THE ERN CONUS AND GULF STATES TO KEEP RETURN 
MOISTURE MINIMAL. FOR NOW...WL LEAVE FCST DRY WITH A LEVELING-OFF OF 
THE WARMING TREND INTO MIDWEEK AS THIS WAVE FLATTENS THE UPR LVL 
RIDGING INTO A MORE ZONAL FLOW PATTERN. 

MEX GUIDANCE VALUES LOOK REASONABLE AND HAVE FOLLOWED SIMILAR TRENDS.


.ILX...WINTER STORM WATCH LATE THURSDAY NIGHT AND FRIDAY ROUGHLY 
ALONG AND NORTH OF A SHELBYVILLE TO PARIS LINE.

$$
SMITH/PLAHMER