FXUS63 KDVN 260333
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
933 PM CST WED NOV 25 2009

.UPDATE...
MAIN CHALLENGE IS IF/WHEN TIMING OF CHANGEOVER TO SNOW WILL HAPPEN
WHICH ALONG WITH WARM GROUND TEMPS TO LOOM QUITE LARGE IN 
WHETHER ANY SNOW ACCUMS. UPPER LOW AND ATTENDANT RAIN AREA WAS
LOCATED OVER EASTERN IA GRADUALLY MOVING TO THE E. REGIONAL RADAR
MOSAIC SHOWS DEFORMATION ZONE DROPPING SOUTH THROUGH SOUTHEAST MN
AND SOUTHERN WI ATTIM... AND THIS WILL ROTATE DOWN ACROSS MUCH OF
THE AREA ESPECIALLY FROM QUAD CITIES N/E OVRNGT. SO FAR PCPN IN 
CWA HAS BEEN MAINLY COLD RAIN BUT DID HAVE ONE REPORT EARLIER IN
THE EVE OF SOME FLAKES MIXING IN ALONG THE HWY 150 CORRIDOR... AND
MOST LIKELY PER RECENT OBS THAT A RASN MIX OCCURRING IN SOME
AREAS ACROSS THE NORTH WHILE SNOW JUST WEST OF CWA WHERE BEST COLD
ADVECTION NOTED. ALSO REPORT OF CARS AND GRASS COVERED WITH SNOW 
IN LACROSSE WI. BL REMAINS WARM WITH LATEST RUC SHOWING WET BULB
TEMPS OF AROUND +1C TO 1.5C IN 0-500M LAYER ALONG AND EAST OF THE
MISSISSIPPI RIVER... THOUGH LOWERING TO AROUND 0.5C IN NORTH/WEST.
RUC SUGGESTS THIS LAYER TO REMAIN TOO WARM MOST AREAS FOR COMPLETE
CHANGEOVER TO SNOW INTO THE EARLY AM WITH LAYER GRADUAL COOLING TO
AROUND 0C ALL BUT FAR S/E... SUGGESTING INCREASE IN MAINLY MIX OF
RASN. ALSO COMPLICATING THINGS IS SLIGHTLY WARM DRAW WRAPPING IN
FROM N/E ATTENDANT TO TROWAL/WARM CONVEYOR... WITH RUC SUGGESTING
0-500M WET BULB TEMPS STAYING AROUND 0C OR A LITTLE ABOVE MUCH OF
AREA EAST OF MISSISSIPPI THROUGH DAYBREAK WHICH WOULD SUPPORT
STAYING MOSTLY A MIX THOUGH POTENTIAL SWITCH OVER TO SNOW DURING
BOUT OF MORE ROBUST LIFT. SO BEST POTENTIAL FOR COMPLETE CHANGE TO
SNOW LOOKS TO RESIDE WEST OF MISSISSIPPI AND ESPECIALLY W/S OF THE
QUAD CITIES... WHILE BULK OF PCPN FROM QUAD CITIES N/E. GIVEN ALL
OF THIS WILL UPDATE TO DELAY CHANGEOVER AND HANG ONTO MORE OF 
A MIX OF RASN LONGER... AND ALONG WITH WARM/WET GROUND WILL ALSO
LOWER ACCUMS. STILL EXPECT CARS...GRASS AND ROOFTOPS COVERED IN
WITH SNOW SOME AREAS.  

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$