MESOSCALE DISCUSSION 2340
   NWS STORM PREDICTION CENTER NORMAN OK
   1143 PM CST FRI NOV 18 2011
   
   AREAS AFFECTED...EASTERN WY TO SOUTHWEST/CENTRAL SD
   
   CONCERNING...HEAVY SNOW 
   
   VALID 190543Z - 191015Z
   
   BANDS OF MODERATE TO HEAVY SNOW ARE EXPECTED TO DEVELOP
   EAST-NORTHEASTWARD OVERNIGHT FROM EASTERN WY ACROSS
   SOUTHWEST/CENTRAL PORTIONS OF SD. SNOWFALL RATES MAY EXCEED 1 IN/HR.
   
   PER WATER VAPOR/IR SATELLITE IMAGERY...INCREASING IMPLIED DEEP
   FORCING FOR ASCENT CONTINUES TO SPREAD EASTWARD AND EMERGE FROM THE
   NORTH-CENTRAL ROCKIES LATE THIS EVENING AHEAD OF A BRITISH
   COLUMBIA/PACIFIC NORTHWEST-CENTERED BROAD UPPER TROUGH. LIFT/ASCENT
   WILL BE FURTHER AIDED BY A DEVELOPING COUPLED UPPER JET STRUCTURE AS
   WELL AS LOW-LEVEL UPSLOPE IN VICINITY OF THE BLACK HILLS. AS THIS
   FORCING TREND CONTINUES/BOUNDARY LAYER QUICKLY SATURATES...SNOW WILL
   CONTINUE TO INCREASE IN INTENSITY/SPREAD EAST-NORTHEASTWARD
   OVERNIGHT FROM EAST-CENTRAL/NORTHEAST WY ACROSS SOUTHWEST-CENTRAL SD
   THROUGH 09Z-12Z. THESE BANDS OF SNOW WILL BE COINCIDENT WITH A
   SOUTHWEST-NORTHEASTWARD ORIENTAL ELEVATED BAROCLINIC/FRONTOGENETICAL
   ZONE...WITH THE HEAVIEST SNOW POTENTIALLY MAXIMIZED IN A 50 MILE
   WIDE /OR LESS/ CORRIDOR ALONG THIS WSW-ENE AXIS AS PER VARIOUS
   HIGH-RES NUMERICAL GUIDANCE. LIFT COINCIDENT WITH AN INCREASINGLY
   SATURATED DENDRITIC LAYER...ATOP AN INCREASINGLY COLDER/ISOTHERMAL
   LOWEST 2-3 KM...WILL SUPPORT SNOWFALL RATES IN EXCESS OF 1 IN/HR FOR
   A FEW HOURS DURATION THROUGH THE OVERNIGHT/EARLY MORNING HOURS.
   
   ..GUYER.. 11/19/2011
   
   
   ATTN...WFO...ABR...UNR...
   
   LAT...LON   44370439 44860352 45129923 44139923 44050025 43910190
               43870328 43840388 44370439