000 FXUS63 KILX 100831 AFDILX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 231 AM CST FRI FEB 10 2012 .DISCUSSION... ISSUED 230 AM CST FRI FEB 10 2012 SHARP COLD FRONT IS MAKING STEADY PROGRESS TOWARD THE AREA... CURRENTLY BISECTING IOWA FROM SOUTHWEST TO NORTHEAST. WATER VAPOR IMAGERY SHOWING THE DEEP TROUGH MARKING THE ARCTIC AIR CURRENTLY JUST SOUTH OF THE CANADIAN BORDER...WHILE ANOTHER WAVE WAS IN THE SOUTHERN JET STREAM FROM NEAR KANSAS CITY SOUTHWEST INTO TEXAS. THE MAIN FORECAST CONCERNS FOR THIS PACKAGE INVOLVE TIMING AND TYPE OF PRECIPITATION TODAY...THE VERY COLD AIR FOR THE WEEKEND... AND POTENTIAL SNOWFALL MONDAY AND MONDAY NIGHT. SHORT TERM...TODAY THROUGH SUNDAY... 00Z MODELS HAVE SLOWED DOWN A TAD ON THE FRONTAL PASSAGE TODAY... WITH GENERAL CONSENSUS PLACING IT NEAR THE ILLINOIS RIVER BY 9 AM...AND APPROACHING I-57 DURING MID AFTERNOON. PRECIPITATION SHOULD BEGIN TO FILL IN FROM THE SOUTH AND NORTH TOWARD MID TO LATE MORNING. WITH THE SLOWER FRONTAL SPEED...MODEL SOUNDINGS ARE SHOWING A TRANSITION TO RAIN OVER THE I-55 CORRIDOR LATE MORNING...AND REMAINING RAIN ACROSS THE EASTERN CWA UNTIL MID TO LATE AFTERNOON. HAVE GONE WITH THE HIGHEST POPS ACROSS THE EAST DURING THE AFTERNOON HOURS. ANY LINGERING LIGHT SNOW OR FLURRIES SHOULD MOVE INTO INDIANA BY MIDNIGHT. STRONG 1046 MB HIGH PRESSURE TO DROP INTO THE CENTRAL PLAINS BY MIDDAY SATURDAY...THEN DRIFT INTO THE LOWER MISSISSIPPI VALLEY WHILE SLOWLY WEAKENING. WHILE THIS WILL RESULT IN FAIR SKIES THROUGH THE WEEKEND...THE PRESSURE GRADIENT WILL KEEP BLUSTERY NORTHWEST WINDS UP THROUGH MOST OF SATURDAY. GUSTS OF 30-35 MPH WILL BE POSSIBLE...ESPECIALLY TONIGHT AND EARLY SATURDAY. TEMPERATURE-WISE...HIGHS ACROSS THE WESTERN CWA TODAY WILL BE DURING THE MORNING HOURS...AND FROM MIDDAY TO EARLY AFTERNOON IN THE EAST. HAVE TRENDED THE HOURLY TEMPERATURE GRIDS ACCORDINGLY... WITH FALLING TEMPERATURES MOST AREAS THROUGH THE AFTERNOON. HAVE MADE LITTLE CHANGE TO THE TEMPERATURES THE REMAINDER OF THE WEEKEND...WITH HIGHS ONLY IN THE 20S. COLDEST WEATHER EXPECTED SATURDAY NIGHT...WITH MUCH OF THE CWA FALLING TO 10 DEGREES OR LOWER. LONG TERM...MONDAY THROUGH THURSDAY... SHORTWAVE CURRENTLY OFF THE PACIFIC COAST WILL BE MOVING INTO THE CENTRAL PLAINS BY MONDAY MORNING. MEDIUM RANGE MODELS ALL SHOWING A RAPID SURGE IN MOISTURE AHEAD OF THIS SYSTEM LATE SUNDAY NIGHT...AS THE FLOW AHEAD OF THIS WAVE COMES UP OFF THE GULF OF MEXICO. HAVE INCREASED PRECIPITATION CHANCES TO THE LIKELY RANGE ACROSS THE WESTERN CWA ON MONDAY...AND ACROSS THE EAST MONDAY NIGHT. FORECAST SOUNDINGS INDICATING THIS SHOULD LARGELY BE SNOW...WITH A POTENTIAL RAIN/SNOW MIX IN THE SOUTHEAST CWA MONDAY AFTERNOON. INITIAL THOUGHTS ARE THAT A COUPLE INCHES OF SNOW MAY BE POSSIBLE...BUT MODEL SOLUTIONS MAY BE ADJUSTING ONCE THE WAVE STARTS BEING SAMPLED BY THE UPPER AIR NETWORK IN THE NEXT DAY OR SO. NEXT PRECIPITATION FOCUS IS TOWARD THE END OF THE WEEK. GFS HAS SIGNIFICANTLY SHIFTED SOUTHWARD AND IS MUCH CLOSER TO THE ECMWF...ALTHOUGH STILL A BIT FURTHER NORTH. THE LATTER SOLUTION WOULD KEEP US DRY THROUGH THE END OF THE WEEK. HAVE STARTED TRENDING DOWNWARD ON POPS LATE IN THE WEEK...BUT POOR RUN TO RUN CONSISTENCY THE LAST FEW DAYS CAUSES SOME HESITATION ON COMPLETELY PULLING THEM AT THIS TIME. GEELHART && .AVIATION... ISSUED 1149 PM CST THU FEB 9 2012...FOR THE 06Z TAFS CLOUD HEIGHTS WILL REMAIN VFR AT 035-040 THE REST OF THE NIGHT...WITH CIGS LOWERING TO MVFR AS PRECIPITATION BEGINS TO DEVELOP BETWEEN 15Z-18Z WHEN THE COLD FRONT MOVES OVER THE TERMINALS. PRECIP MAY CHANGE OVER TO RAIN AROUND 18Z FOR SPI/CMI/DEC AS WARM AIR AT THE SURFACE BECOMES DEEP ENOUGH TO MELT THE ICE CRYSTALS. WE ADDED -RASN WEATHER FOR THE FIRST 4-5 HOURS OF PRECIP TO ACCOUNT FOR THE POSSIBLE MIX. AS TEMPS DROP BEHIND THE FRONT...PRECIP WILL CHANGE BACK TO ALL SNOW...WITH ANY LIQUID STILL ON THE GROUND FREEZING AND CREATING SLIPPERY CONDITIONS. VIS IN SOME SNOW SHOWERS MAY DIP TO IFR FOR CMI/DEC...AS THEY WILL BE CLOSER TO THE HEAVIER SNOW POTENTIAL. THE OTHER SITES SHOULD REMAIN MVFR DUE TO VIS/CIGS. A HALF INCH OF SNOW MAY FALL FOR CMI... WITH A COUPLE OF TENTHS OF SNOW EXPECTED AT THE OTHER TERMINAL SITES. SNOW SHOULD TAPER OFF FRIDAY EVENING TO JUST FLURRIES...OR END ALTOGETHER. WINDS WILL INCREASE OUT OF THE SW AHEAD OF THE FRONT...WITH SOME GUSTS TO 20KT DURING THE EARLY AFTERNOON. BEHIND THE FRONT...STRONG NW WINDS WILL DEVELOP WITH GUSTS TO 25KT. BY MIDNIGHT...WINDS SHOULD BECOME NEARLY NORTH...AND INCREASE EVEN HIGHER TO SUSTAINED 17-20KT AND GUSTS NEAR 30KT. SHIMON && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$