[MCD] SWOMCD

[MCD at goshenarc.org]

ACUS11 KWNS 241831
SWOMCD
SPC MCD 241831 
MIZ000-OHZ000-INZ000-ILZ000-250000-

MESOSCALE DISCUSSION 2464
NWS STORM PREDICTION CENTER NORMAN OK
1231 PM CST WED NOV 24 2004

AREAS AFFECTED...CNTRL/NE IL INTO NW IN AND SRN LOWER MI

CONCERNING...HEAVY SNOW 

VALID 241831Z - 250000Z

SW-NE ORIENTED BAND OF MDT TO HEAVY WET SNOW TO CONTINUE TO
INTENSIFY ACROSS WCNTRL/NE IL REMAINDER OF THE AFTERNOON...
DEVELOPING/INTENSIFYING NEWD ACROSS NW IN AND SRN LOWER MI IN
21Z-00Z TIMEFRAME. SNOWFALL RATES AS HIGH AS 1.0-1.5 IN/HR OF WET
SNOW WILL BE POSSIBLE THROUGH THE AFTERNOON...ALTHOUGH ACCUMULATIONS
WILL GENERALLY BE HAMPERED BY MILD GROUND TEMPS/LOW SNOW-LIQUID
EQUIVALENTS.

LATEST IR SATELLITE IMAGERY PORTRAYS COOLING CLOUD TOPS ACROSS NRN
IL ASSOCIATED WITH UPPER TROUGH OVER THE MID MISSISSIPPI VALLEY.
SEVERAL INTENSE BANDS OF MDT-HVY SNOW AND/OR MIXED PRECIP ARE
EVIDENT IN VOLUMETRIC RADAR DATA /IN ACCORDANCE WITH SFC OBS/ ACROSS
WCNTRL INTO NCNTRL IL AT 18Z. COLD AIR ADVECTION/DYNAMIC COOLING
ASSOCIATED WITH CYCLONE EXPECTED TO EFFECTIVELY CHANGE P-TYPE OVER
TO ALL SNOW...OVERCOMING SHALLOW WARM LAYER WHERE A MIX AND/OR ALL
RAIN PERSISTS AT MIDDAY.

MORNING UPPER AIR DATA DEPICTED COUPLED UPPER JET STRUCTURE ACROSS
THE MID MISSISSIPPI VALLEY...WITH 12Z NUMERICAL GUIDANCE SUGGESTING
ASSOCIATED ENHANCED UVVS WILL SPREAD ACROSS NE IL/SRN LOWER MI
THROUGH THE AFTERNOON.

SW-NE MID LEVEL FRONTOGENETICAL FORCING IN 800-600 MB LAYER WILL
ULTIMATELY FOCUS HEAVIEST SNOWBALL IN SIMILAR ORIENTATION FROM
WCNTRL/NE IL INTO NW IN AND SRN LOWER MI...NAMELY FOCUSED ALONG
SPI-PIA-IKK-SBN-LAN CORRIDOR. FURTHERMORE...PROXIMITY OF UNSTABLE
AIRMASS -- AS EVIDENT IN 6.8 C/KM MID LEVEL LAPSE RATE IN 12Z ILX
RAOB AND CG LIGHTNING OVER PAST FEW HOURS FROM NE MO INTO WCNTRL IL
AMIDST MID/HEAVY SNOW -- WILL CONTRIBUTE TO LOCALLY ENHANCED SNOW
RATES.

ACROSS THE CHICAGO METRO AREA...E/NE TRAJECTORIES ACROSS UPPER
40S/LOWER 50S F SRN LAKE MICHIGAN WILL LIKELY KEEP BOUNDARY LAYER
ABOVE 32F FOR MUCH OF THE AFTERNOON...SUGGESTING HEAVIEST SNOW
ACCUMULATIONS WILL BE CONFINED TO FAR SWRN/SRN SUBURBS AND NW IN.

..GUYER.. 11/24/2004

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

...NOTICE...
SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A 
SCHEDULED BASIS...FOUR TIMES A DAY...BETWEEN 05-06 UTC...
11-12 UTC...17-18 UTC...AND 23-00 UTC AS SIGNIFICANT SHORT
RANGE WINTER WEATHER EVENTS UNFOLD.  THIS SCHEDULE WILL BE
USED FROM DECEMBER 1 THROUGH FEBRUARY 28 TO ALLOW PARTNERS
AND USERS TO BETTER ANTICIPATE THE TIMING OF SPC WINTER WEATHER
MESOSCALE DISCUSSIONS.

ATTN...WFO...DTX...IWX...GRR...IND...LOT...ILX...LSX...DVN...

41748919 41978857 41688739 41998661 42968599 43708430
43508321 42728283 41998420 40668653 39748832 39168978
39399041 39629079 40369115 40779086 

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