Issued by NWS Central Illinois
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000 FXUS63 KILX 261115 AFDILX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 615 AM CDT SUN OCT 26 2008 .DISCUSSION... ISSUED 321 AM CDT SUN OCT 26 2008 SHORT TERM MODELS IN FAIRLY GOOD AGREEMENT AND ARE CONSISTENT WITH PREVIOUS RUNS ON HANDLING OF THE FAST MOVING COLD FRONT TODAY. ONLY DIFFERENCE SEEN IS WITH THEIR HANDLING OF THE PCPN MOVING ACROSS IOWA AT THE MOMENT. GFS SEEMS TO HANDLE THIS BETTER THAN THE NAM-WRF...THOUGH NOT AS WELL AS WOULD HAVE HOPED. ANY RATE...RH FIELDS ON GFS LOOKS BETTER THAN NAM SO WILL LEAN THAT DIRECTION FOR THIS MORNING. A BLEND OF THE MODELS FOR THE REST LOOKS FINE. IN THE LONG TERM...THE ECMWF STILL LOOKS GOOD. MAIN CONCERN THIS PACKAGE IS WITH PCPN THIS MORNING...GUSTY WINDS TODAY AND FREEZING TEMPS TONIGHT AND MONDAY NIGHT. LONG TERM CONCERNS IS SPEED OF ANY WARM UP. SHORT TERM...TODAY THROUGH TUESDAY NIGHT COLD FRONT HAS REACHED THE IOWA/ILLINOIS BORDER AND IS QUICKLY MOVING SOUTHEAST INTO THE AREA. BEHIND THE FRONT IS AN AREA OF SHOWERS THAT WILL AFFECT MOST OF THE CWA THIS MORNING...PRIOR TO 18Z. WINDS WILL BECOME NORTHWEST AND INCREASE TO 25-35 MPH WITH GUSTS TO AROUND 45 MPH. ADVISORY STILL MAKES SENSE AND WILL CONTINUE UNTIL 02Z THIS EVENING. SKIES WILL BECOME MOSTLY SUNNY BEHIND FRONT/PCPN BUT GUSTY WINDS WILL MAKE IT QUITE CHILLY. WINDS SHOULD DECOUPLE SOME THIS EVENING BUT GRADIENT WILL REMAIN TIGHT COULD STILL BE SOME GUSTS AT NIGHT...BUT NOT ADVISORY CRITERIA. A SECONDARY 500MB AND SFC TROUGH WILL DROP INTO THE REGION FOR MONDAY AND THIS COULD BRING ADDITIONAL PCPN TO THE REGION. 850 TEMPS WILL BE BELOW ZERO WHICH MEANS PCPN COULD BE FLURRIES EARLY CHANGING TO ALL SPRINKLES OR A MIX. CONFIDENCE IS NOT HIGH WITH THIS AND DUE TO LACK OF MOISTURE...BELIEVE CHANCES ARE SMALL. SO HAVE GONE WITH SLIGHT CHANCE OF PCPN FOR MONDAY...WHICH WILL NOT SHOW UP IN TEXT FORECAST. AFTER THIS...THE LARGE HIGH PRESSURE WILL FINALLY BUILD INTO THE REGION FOR TUESDAY AND THE REST OF THE WEEK...WITH DRY WEATHER. COLD AIR ADVECTION WILL BE THE RULE FOR MOST OF THE PERIOD AS 500MB TROUGH DEVELOPS IN THE EASTERN US AND A COLD HIGH PRESSURE SLIDES DOWN INTO THE PLAINS. ILLINOIS WILL BE INFLUENCE BY NORTHERLY FLOW FOR THE NEXT 3 DAYS GIVING US BELOW NORMAL TEMPS THROUGH THE PERIOD. TEMPS WILL GET COLD TONIGHT...BUT BREEZY WINDS WILL KEEP THEM FROM FALLING TOO FAR. THE STRONG CAA WILL STILL BRING BELOW FREEZING TEMPS TO MOST OF THE CWA TONIGHT. THEN WE`LL SEE HIGH TEMPS MONDAY 15-20 DEGREES BELOW NORMAL. A HARD FREEZE WILL BE IN STORE FOR MONDAY NIGHT OVER THE ENTIRE CWA AS SKIES WILL BE CLEAR...WINDS WILL BE LIGHT AND A SECOND SHOT OF COLD AIR WILL HAVE DROPPED INTO THE AREA. TEMPS WILL REMAIN BELOW NORMAL FOR TUE AND TUE NIGHT. GUIDANCE TEMPS NOT TOO BAD BUT DID UNDERCUT HIGHS FOR MON AND TUE IN SOME AREAS. LONG TERM...WEDNESDAY THROUGH SATURDAY HIGH PRESSURE WILL GRADUALLY SHIFT INTO SOUTHEASTERN US THROUGH THE PERIOD AND BRING SOUTHWESTERLY FLOW BACK TO ILLINOIS. THIS SHOULD BRING RETURN OF WAA TO THE AREA FOR THE PERIOD. GFS SEEMS FAST WITH BRING THE NEXT FRONT INTO THE AREA WHILE ECMWF APPEARS TO BE THE BETTER SOLUTION WHICH IS SLOWER. WARM UP IN THE AREA WILL LIKELY BE SLOWER THAN MEX GUIDANCE INDICATES SO WILL UNDERCUT MEX NUMBERS BY SEVERAL DEGREES. AUTEN && .AVIATION... ISSUED 615 AM CDT SUN OCT 26 2008 COLD FRONT NOW MOVING THRU IL WILL BRING STRONG WLY/NWLY SFC WNDS TO ALL OF THE TERMINALS TDY. STRONGEST WNDS WILL BEGIN AS VERTICAL MIXING TAKES PLACE TWD 16Z. EXPECT 20-30 KT SUSTAINED COMMON WITH GUSTS ABV 40 KT AT TIMES. GUSTINESS SHOULD SETTLE SOMEWHAT AFT 00Z MON...BUT SUSTAINED SPEEDS WILL STILL REACH 20 KT. A BAND OF SHRA ASSOC WITH THE FRONTAL BNDRY WILL MOVE QUICKLY THRU THE AREA...AND SHOULD BE E OF THE TAF SITES BY 18Z TDY. PCPN WILL BE LGT...AND CIGS/VSBYS WILL REMAIN IN THE VFR CATEGORY. SVRL SHORTWAVES ARE APPARENT IN SATELLITE IMAGERY BEHIND THE FRONT IN THE NWLY UPPER FLOW EXTENDING WELL BACK INTO CANADA...HOWEVER THESE FEATURE WILL JUST BRING INTERMITTENT MID/HIGH CLOUDS. 04 && .ILX WATCHES/WARNINGS/ADVISORIES... FREEZE WARNING FROM 1 AM TO 9 AM CDT MONDAY FOR ILZ027>031- 036>038-040>057-061. WIND ADVISORY FROM 10 AM THIS MORNING TO 9 PM CDT THIS EVENING FOR ILZ027>031-036>038-040>057-061. && $$
