479
FXUS63 KILX 091151
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
551 AM CST TUE FEB 9 2010
DISCUSSION
ISSUED 225 AM CST TUE FEB 9 2010
SNOWFALL ACCUMULATION OVER MUCH OF THE CWA HAS BEEN IN THE 2 TO 4
INCH RANGE SO FAR. AREAS NEAR THE INDIANA BORDER WERE THE LAST TO
SEE THE SNOW ARRIVE LAST EVENING...BUT SOME OF THE HEAVIER BANDS
ARE CURRENTLY IN THAT AREA...WHERE ISENTROPIC LIFT IS CURRENTLY
MAXIMIZED PER LATEST RUC MODEL. REGIONAL RADAR MOSAICS SHOWING THE
DRY SLOT APPROACHING QUINCY. INVERTED TROUGH AXIS CURRENTLY IS
ALONG THE WESTERN EDGE OF THE CWA...AND TEMPERATURES TO THE WEST
OF IT HAVE BEEN RAPIDLY FALLING...WITH QUINCY FALLING FROM 26F TO
12F IN 2 HOURS.
MAIN FORECAST ISSUE INVOLVES AMOUNT OF ADDITIONAL SNOWFALL...PLUS
DEVELOPMENT OF BLOWING SNOW LATER TODAY ON THE BACK SIDE OF THE
TROUGH.
SHORT TERM...TODAY THROUGH THURSDAY...
SHORT-RANGE MODELS IN GOOD AGREEMENT WITH TRACKING THE SURFACE
TROUGH ACROSS THE CWA THROUGH THE MORNING...AS STRONG UPPER LOW
SWINGS EASTWARD...PASSING JUST SOUTH OF THE I-72 CORRIDOR THIS
AFTERNOON AND EVENING. SNOWFALL ACROSS THE SOUTHERN CWA SHOULD
DIMINISH A BIT...BUT WRAPAROUND SNOWS BEHIND THE UPPER LOW ARE
EXPECTED THIS AFTERNOON. MAY SEE ANOTHER 2-3 INCHES ACROSS THE
NORTHERN CWA NORTH OF I-74 TODAY. WINDS EXPECTED TO PICK UP ACROSS
THE SOUTHWEST CWA THIS MORNING...AND ACROSS THE EAST THIS
AFTERNOON. STRONGEST WINDS EXPECTED FROM ABOUT MIDNIGHT THROUGH
MID MORNING WEDNESDAY WITH GUSTS OF 30-35 MPH. DRY NATURE OF THE
SNOW SHOULD READILY ALLOW FOR BLOWING AND DRIFTING SNOW AS THE
WINDS INCREASE...WITH NEAR-WHITEOUT CONDITIONS AT TIMES. WINDS AND
BLOWING SNOW EXPECTED TO DIMINISH AS A HIGH PRESSURE RIDGE PUSHES
EAST TOWARD THE MISSISSIPPI VALLEY...AND WILL BE CENTERED OVER THE
AREA BY THURSDAY MORNING.
TEMPERATURES ALSO ARE A CONCERN. HOURLY GRIDS WILL REFLECT FALLING
TEMPERATURES OVER MUCH OF THE AREA THIS MORNING...ESPECIALLY IN
THE WEST...WITH SOME MINOR RECOVERY THIS AFTERNOON. HAVE UNDERCUT
GUIDANCE TEMPERATURES TONIGHT THROUGH THURSDAY WITH THE FRESH SNOW
COVER. COLDEST WEATHER EXPECTED WEDNESDAY NIGHT AND THURSDAY AS
THE RIDGE MOVES OVERHEAD. MAY SEE NEAR ZERO READINGS WEST OF THE
ILLINOIS RIVER BY THURSDAY MORNING...WITH SINGLE DIGITS PREVALENT
ELSEWHERE. WIND CHILLS EXPECTED TO FALL INTO THE SINGLE DIGITS
TONIGHT...THEN INTO THE 5 TO 10 BELOW RANGE IN THE NORTHWEST CWA
WEDNESDAY NIGHT.
LONG TERM...FRIDAY THROUGH MONDAY...
A COUPLE OF FEATURES OF INTEREST IN THE EXTENDED PORTION OF THE
FORECAST. THE FIRST IS A CLIPPER SYSTEM WHICH WILL MOVE THROUGH
THE AREA FRIDAY NIGHT. GFS IS MUCH FASTER THAN THE ECMWF WITH THE
INITIAL SYSTEM...BUT BOTH SHOW A CLOSED UPPER LOW DIVING SOUTHEAST
INTO THE MIDWEST LATER IN THE WEEKEND. THE LATTER SYSTEM APPEARS
TO BE MORE OF A PRECIPITATION THREAT...AND WILL NEED TO BE
MONITORED. TEMPERATURES ARE EXPECTED TO REMAIN WELL BELOW NORMAL
THROUGH THE PERIOD.
GEELHART
AVIATION
ISSUED 551 AM CST TUE FEB 9 2010
A MAJOR WINTER STORM WILL CONTINUE TO IMPACT THE CENTRAL ILLINOIS
TERMINALS THROUGH THE 12Z TAF PERIOD. DRIER AIR IS CURRENTLY
WRAPPING INTO THE SYSTEM AND THIS HAS CAUSED SNOWS TO TAPER OFF
AND CIGS/VSBYS TO IMPROVE TO MVFR/VFR. STILL EXPECT A RENEWED THREAT FOR
LOWER CIGS/VSBYS INTO THE IFR CATEGORY LATER TODAY INTO TONIGHT AS
AN ADDITIONAL AREA OF SNOW WRAPS INTO THE REGION ON THE BACK SIDE
OF THE STORM. LIGHT/VARIABLE WINDS EARLY TODAY WILL BECOME GUSTY
OUT OF THE WEST/NORTHWEST BY LATE AFTERNOON/EARLY EVENING AND
LINGER THROUGH THE NIGHT. THESE GUSTY WINDS SHOULD PRODUCE AREAS
OF BLOWING AND DRIFTING SNOW.
BAK
ILX WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY UNTIL 6 AM CST WEDNESDAY FOR ILZ040>042-
047>057-061>063-066>068-071>073.
WINTER STORM WARNING UNTIL NOON CST WEDNESDAY FOR ILZ027>031-
036>038-043>046.
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