[MCD] SWOMCD

Wed Dec 14 00:38:17 UTC 2005

ACUS11 KWNS 140035
SWOMCD
SPC MCD 140035 
IAZ000-MNZ000-140430-

MESOSCALE DISCUSSION 2553
NWS STORM PREDICTION CENTER NORMAN OK
0635 PM CST TUE DEC 13 2005

AREAS AFFECTED...SCNTRL MN...NCNTRL IA

CONCERNING...PRECIPITATION TRENDS...WINTER PRECIPITATION 

VALID 140035Z - 140430Z

A BRIEF PERIOD OF LIGHT FREEZING RAIN COULD OVERSPREAD PORTIONS OF
NCNTRL IA AND SCNTRL MN OVER THE NEXT FEW HOURS. LIGHT GLAZE AMOUNTS
MAY CAUSE HAZARDOUS DRIVING CONDITIONS BEFORE A CHANGEOVER TO LIGHT
SNOW.

A SWATH OF PRIMARILY LIGHT RAIN WAS DEVELOPING ENEWD ACROSS THE MO
RIVER VALLEY THIS EVENING. THIS PRECIPITATION WAS OCCURRING WITHIN
STRONG WARM CONVEYOR BELT...AND BENEATH PRONOUNCED DPVA...
ASSOCIATED WITH A SHORT WAVE DISTURBANCE MOVING ACROSS THE PLAINS.
SUB-FREEZING SURFACE-BASED AIR MASS BLANKETS ALL OF NERN IA AND SERN
MN...WITH THE 32F ISOTHERM ROUGHLY RUNNING SOUTH TO NORTH ACROSS
NCNTRL IA TO SCNTRL MN ATTM. A NARROW AXIS OF WARMER AND DRIER AIR
ALOFT WAS OVERSPREADING PARTS OF IA AND SRN MN...JUST AHEAD OF THE
DEVELOPING PRECIPITATION...BASED ON LATEST SHORT-TERM GUIDANCE AND
00Z RAOBS.

NEAR FREEZING WET-BULB TEMPERATURES WITHIN THE ELEVATED DRY LAYER
WILL LIKELY RESULT IN A TRANSITION TO ISOTHERMAL PROFILES COLD
ENOUGH TO SUPPORT LIGHT SNOW AS PRECIPITATION PERSISTS ACROSS THE
REGION LATER TONIGHT. HOWEVER...WITH THE ONSET OF EVAPORATIVE
COOLING IN THIS WARM LAYER...THERE MAY BE ENOUGH POSITIVE AREA ALOFT
TO SUPPORT A BRIEF PERIOD OF LIGHT FREEZING RAIN. HOURLY
PRECIPITATION AMOUNTS OF 0.01-0.05 INCHES HAVE BEEN OCCURRING
UPSTREAM. THESE LIGHT AMOUNTS FALLING AS FREEZING RAIN COULD MAKE
ROADWAYS HAZARDOUS BEFORE PRECIPITATION CHANGES OVER TO LIGHT SNOW.

..CARBIN.. 12/14/2005

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...MPX...DMX...FSD...

42459400 43049459 43759487 44229483 44319429 43949361
43459327 42909311 42509306 42219309 42149351 

WWWW