[MCD] SWOMCD

Wed Nov 29 22:41:28 UTC 2006

ACUS11 KWNS 292243
SWOMCD
SPC MCD 292243 
WIZ000-ILZ000-IAZ000-MOZ000-300245-

MESOSCALE DISCUSSION 2239
NWS STORM PREDICTION CENTER NORMAN OK
0443 PM CST WED NOV 29 2006

AREAS AFFECTED...NORTHEAST MO/EASTERN IA AND SOUTHWEST WI/NORTHWEST
IL

CONCERNING...WINTER MIXED PRECIPITATION 

VALID 292243Z - 300245Z

FREEZING RAIN/SLEET WILL STEADILY INCREASE ACROSS EASTERN IA INTO
SOUTHWEST WI/NORTHWEST IL THROUGH EARLY/MID EVENING. SOME ICE
ACCUMULATION WILL BE POSSIBLE VIA HOURLY LIQUID EQUIVALENT RATES OF
0.05 IN/HR OR GREATER.

COINCIDENT WITH PRONOUNCED BAROCLINIC ZONE...CLOUD TOPS CONTINUE TO
COOL AND EXPAND INTO THE MIDDLE/UPPER MISSISSIPPI VALLEY PER WATER
VAPOR/INFRARED SATELLITE TRENDS. PER RADAR MOSAICS...CONVECTIVE
PRECIPITATION ELEMENTS CONTINUE TO SURGE NORTHEASTWARD ACROSS
NORTHERN MO INTO EASTERN IA/FAR NORTHWEST IL LATE THIS
AFTERNOON...INCLUDING SOME EMBEDDED CLOUD-GROUND LIGHTNING. AS
SUGGESTED BY RUC SOUNDINGS AND A RECENT TAMDAR SOUNDING FROM CEDAR
RAPIDS IA...THE POST-FRONTAL ENVIRONMENT WITHIN THIS CORRIDOR IS
CHARACTERIZED BY AN ELEVATED WARM LAYER ATOP A SHALLOW /APPROX 1 KM/
SUB-FREEZING LAYER. THUS AS PRECIPITATION RATES INCREASE...FREEZING
RAIN/SOME SLEET WILL BECOME INCREASINGLY PREVALENT ACROSS FAR
EASTERN IA INTO SOUTHWEST WI/NORTHWEST IL THROUGH EARLY/MID EVENING.

AIDED BY EMBEDDED CONVECTIVE ELEMENTS...A QUICK CHANGE-OVER TO
FREEZING RAIN HAS ALREADY OCCURRED AT KIRKSVILLE MO AND
OTTUMWA/CEDAR RAPIDS IA. A SIMILAR TREND IS EXPECTED THROUGH EARLY
EVENING INTO THE DUBUQUE AND QUAD CITIES AREAS /PERHAPS BY
01Z-02Z/...WITH THE SURFACE WET BULB ZERO LINE OBSERVED TO BE
DEVELOPING EASTWARD AT A RATE OF 50 MILES EVERY 2-3 HOURS.

..GUYER.. 11/29/2006

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

ATTN...WFO...LOT...ILX...MKX...LSX...DVN...ARX...DMX...EAX...

40779070 40269169 40159290 40719314 41689256 42809144
43369003 42738898 41758966 