MESO: Mesoscale Discussion 2261

ACUS11 KWNS 242330
SWOMCD
SPC MCD 242329
WYZ000-250330-

MESOSCALE DISCUSSION 2261
NWS STORM PREDICTION CENTER NORMAN OK
0529 PM CST MON DEC 24 2007

AREAS AFFECTED...CNTRL/NERN WY

CONCERNING...HEAVY SNOW

VALID 242329Z - 250330Z

SNOW WILL INCREASE DURING THE EVENING WITH RATES OF 1 TO 1.5 INCHES
PER HOUR...AND LOCALLY APPROACHING 2 INCHES PER HOUR IN TERRAIN
FAVORABLE LOCATIONS.

THE AIRMASS CONTINUES TO COOL AND MOISTEN OVER NCNTRL WY AS A
SURFACE COLD FRONT...PRESENTLY FROM JUST SOUTH OF GILLETTE TO
RIVERTON...CONTINUES ITS SWD MOVEMENT. SHORT RANGE MODELS/15 UTC
SREF ARE CONSISTENT IN THE DEVELOPMENT OF MODERATE/STRONG UPWARD
MOTION ASSOCIATED WITH APPROACHING LARGE-SCALE MID-LEVEL
TROUGH...AND ENHANCED BY 700 MB FRONTOGENETICAL COMPONENT.
RUC FORECAST SOUNDINGS AT SHERIDAN AND GILLETTE ARE FAVORABLE FOR
DENDRITIC SNOW WITHIN THE REGION OF MODERATE TO STRONG ASCENT...AND
STEEP LOW-LEVEL LAPSE RATES /SFC-3 KM ABOUT 6 TO 6.5 C/KM/ INDICATE
THE POTENTIAL FOR LOCALIZED CONVECTIVE ELEMENTS. SNOW RATES OF 1
INCH PER HOUR SHOULD DEVELOP BETWEEN 00 AND 03 UTC FROM SHERIDAN TO
BUFFALO...AND ALONG/WEST OF I-90 INTO THE BIGHORN MOUNTAINS. AS THE
700 MB FLOW TURNS NLY/NWLY...SNOW RATES APPROACHING 2 INCHES PER
HOUR ARE POSSIBLE IN TERRAIN FAVORABLE LOCATIONS. SNOW SHOULD THEN
DECREASE FROM THE NORTH AS MODELS/SREF INDICATE THE AREA OF
STRONGEST ASCENT SPREADING SWD ALONG I-25 TOWARD CPR BY 06 UTC.

.BRIGHT.. 12/24/2007

..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...UNR...CYS...BYZ...RIW...

44610751 44860765 44960716 44820676 44540649 44150613
43890604 43500592 43120586 42900598 42800618 42800648
43500692 43960689 44400718

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