[MCD] SWOMCD

[Mesoscale Convective Discussions]

ACUS11 KWNS 210930
SWOMCD
SPC MCD 210929 
WIZ000-ILZ000-IAZ000-MNZ000-211530-

MESOSCALE DISCUSSION 0091
NWS STORM PREDICTION CENTER NORMAN OK
0329 AM CST SUN JAN 21 2007

AREAS AFFECTED...NERN IA TO EXTREME SERN MN/SWRN WI/NWRN IL

CONCERNING...HEAVY SNOW 

VALID 210929Z - 211530Z

MDT TO HVY SNOW SHOULD DEVELOP NEWD FROM THE MO RIVER VALLEY AND
ACROSS PARTS OF THE UPPER MS VALLEY THROUGH THE MORNING. SNOWFALL
RATES UP TO AN INCH PER HOUR APPEAR POSSIBLE.

STRONG DYNAMIC FORCING FOR ASCENT WITHIN COMMA-HEAD OF DEEP LAYER
CYCLONE WILL CONTINUE TO TRANSITION NEWD FROM THE MID MO RIVER
VALLEY THIS MORNING. PRONOUNCED ASCENT OCCURRING WITHIN LEFT EXIT
REGION OF 100KT MID LEVEL JET WAS CURRENTLY SUPPORTING A BROAD AREA
OF MDT TO HVY SNOW ACROSS PARTS OF ERN NEB AND WRN IA.
MEANWHILE...MID LEVEL DRY INTRUSION..CLEARLY EVIDENT IN SATELLITE
IMAGERY...WAS PROBABLY LIMITING SNOWFALL RATES ACROSS PARTS OF CNTRL
AND ERN IA ATTM. EXPECT HEAVIER SNOW TO REDEVELOP TO THE NORTHEAST
THROUGH THE MORNING AS THE MID LEVEL LOW BEGINS OPEN UP AND TRACK
NEWD OVER IA. A ZONE OF MODEST MID/UPPER LEVEL FRONTOGENESIS/LIFT
OCCURRING IN A THERMODYNAMIC REGIME FAVORABLE FOR BOTH VAPOR TO ICE
TRANSPORT AND DENDRITE GROWTH SHOULD EVOLVE ALONG THE MID LEVEL LOW
TRACK. THIS PROCESS IS EXPECTED TO CONTRIBUTE TO AN AXIS OF ENHANCED
SNOWFALL FROM NCNTRL IA TO SWRN WI THROUGH ABOUT 15Z.

..CARBIN.. 01/21/2007

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

...NOTICE...
SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A
SCHEDULED BASIS FROM DECEMBER 1 THROUGH FEBRUARY 28...FOUR
TIMES A DAY...AROUND 00 UTC...06 UTC...12 UTC...AND 18 UTC
FOR SIGNIFICANT SHORT RANGE WINTER WEATHER EVENTS.

ATTN...WFO...MKX...DVN...ARX...MPX...DMX...

42149008 41999347 41839391 42679482 43429402 43659212
43569108 43068978 

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