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
   
   
   ...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