Issued by NWS Central Illinois
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000 FXUS63 KILX 280700 AFDILX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 200 AM CDT TUE OCT 28 2008 .DISCUSSION... ISSUED 200 AM CDT TUE OCT 28 2008 ANOTHER UNSEASONABLY COLD DAY IN STORE ACROSS CENTRAL ILLINOIS TODAY...BEFORE WARMER TEMPERATURES RETURN FOR THE END OF THE WEEK. 06Z SURFACE ANALYSIS SHOWS STRONG HIGH PRESSURE ANCHORED OVER THE CENTRAL CONUS...ALLOWING A COLD CANADIAN AIRMASS TO PENETRATE SOUTHWARD ALL THE WAY TO THE GULF COAST. ALOFT...RIDGING PREVAILS ALONG AND WEST OF THE ROCKIES...WHILE DEEP TROUGH IS IN PLACE EAST OF THE MISSISSIPPI RIVER. SHORT TERM...TODAY THROUGH THURSDAY UPPER TROUGH WILL SLOWLY BEGIN TO SHIFT FURTHER EASTWARD TODAY...RESULTING IN RISING HEIGHTS AND WARMING TEMPS ALOFT. FORECAST SOUNDINGS INDICATE VERY LITTLE MOISTURE IN THE PROFILE AND MUCH WEAKER LAPSE RATES THAN THOSE SEEN YESTERDAY. END RESULT WILL BE MOSTLY SUNNY SKIES...WITH ONLY FEW-SCT DIURNAL CU DEVELOPING. CU-RULE IS WEAKLY NEGATIVE ACROSS EAST-CENTRAL ILLINOIS...WITH MOST FAVORABLE LOCATION FOR CLOUD COVER FURTHER EAST/SOUTH BENEATH THE UPPER TROUGH. DESPITE LOTS OF SUNSHINE TODAY...TEMPS WILL ONLY BE A COUPLE OF DEGREES WARMER THAN YESTERDAY...MAINLY DUE TO THE MUCH COLDER START TO THE DAY AND A CONTINUATION OF N/NW LOW-LEVEL FLOW. WILL FOLLOW THE COOLER MET NUMBERS MOST CLOSELY...WITH AFTERNOON HIGHS ONLY REACHING THE MIDDLE TO UPPER 40S. SURFACE RIDGE APPROACHES FROM THE WEST TONIGHT...PRODUCING CLEAR SKIES AND DIMINISHING WINDS. HAVE UNDERCUT GUIDANCE BY A FEW DEGREES...RESULTING IN LOWS ONCE AGAIN DIPPING INTO THE 20S ACROSS THE BOARD. WARMING TREND WILL BEGIN ON WEDNESDAY...AS UPPER HEIGHTS CONTINUE TO RISE AND SURFACE FLOW BACKS TO W/SW. 850MB TEMPS JUMP INTO THE 3 TO 6C RANGE BY AFTERNOON...SUPPORTING HIGHS WELL INTO THE 50S. EVEN WARMER AIR ARRIVES ON THURSDAY...THANKS TO STRONG S/SW RETURN FLOW ON THE BACKSIDE OF THE DEPARTING HIGH. GIVEN ABUNDANT SUNSHINE AND DRY AIRMASS...WILL GO SEVERAL DEGREES ABOVE GUIDANCE...WITH HIGHS RISING INTO THE MIDDLE TO UPPER 60S. LONG TERM...FRIDAY THROUGH MONDAY GFS/ECMWF BOTH CONTINUE TO INDICATE NEXT FRONTAL BOUNDARY DROPPING THROUGH THE AREA DURING THE FRIDAY/SATURDAY TIME FRAME. 00Z OCT 28 GFS IS A BIT SLOWER WITH THE FRONT THAN ITS PREVIOUS RUNS...SO HAVE FOLLOWED THE MORE CONSISTENT ECMWF HERE. COLD FRONT WILL SINK SOUTHWARD OUT OF THE NORTHERN PLAINS AND PASS THROUGH CENTRAL ILLINOIS DURING THE DAY FRIDAY...BRINGING A FEW CLOUDS AND SLIGHTLY COOLER TEMPS IN THE LOWER 60S. AFTER THAT...ANOTHER COOL AND DRY AIRMASS WILL TAKE HOLD ACROSS THE MIDWEST THIS WEEKEND...WITH TEMPS NEAR OR SLIGHTLY BELOW NORMAL FOR THIS TIME OF YEAR. BARNES && .AVIATION... ISSUED 1155 PM CDT MON OCT 27 2008 SKIES HAVE PRETTY MUCH CLEARED ACROSS THE CENTRAL ILLINOIS TERMINALS LATE THIS EVENING. EXPECT THESE QUIET/VFR CONDITIONS TO PERSIST THROUGH THE 06Z TAF PERIOD AS UPPER/SURFACE RIDGING STARTS TO BUILD INTO THE REGION. STILL EXPECT WINDS TO PICK UP INTO THE 10-15 KT RANGE WITH DIURNAL HEATING TUESDAY...BUT THEY WILL NOT BE NEARLY AS GUSTY AS IN RECENT DAYS. BAK && .ILX WATCHES/WARNINGS/ADVISORIES... FREEZE WARNING UNTIL 9 AM CDT THIS MORNING FOR ILZ027>031- 036>038-040>057-061>063-066>068-071>073. && $$
