MESOSCALE DISCUSSION 2273
   NWS STORM PREDICTION CENTER NORMAN OK
   0656 PM CDT TUE OCT 25 2011
   
   AREAS AFFECTED...PORTIONS OF S CNTRL/SERN WY AND CNTRL CO
   
   CONCERNING...HEAVY SNOW 
   
   VALID 252356Z - 260400Z
   
   SNOW LEVELS WILL CONTINUE TO LOWER THIS EVENING...WITH RATES
   INCREASING TO 1-2 INCH AN HOUR...ESPECIALLY ACROSS HIGHER
   ELEVATIONS. GUSTY WINDS WILL SIGNIFICANTLY REDUCE VISIBILITIES AT
   TIMES.
   
   A POWERFUL PACIFIC UPPER TROUGH WILL CONTINUE TO PROGRESS EWD
   OVERNIGHT...WITH A DUAL JET STRUCTURE FOCUSING ENHANCED VERTICAL
   MOTION ACROSS PORTIONS OF THE ROCKIES. ONE JET WILL STRENGTHEN OVER
   THE NRN INTERMOUNTAIN WEST AND NRN HIGH PLAINS...WHILE A
   SEPARATE...STRONGER JET WILL STRENGTHEN ACROSS THE FOUR CORNERS
   REGION INTO THE CNTRL HIGH PLAINS. DIURNAL AND DYNAMIC COOLING WILL
   CONTRIBUTE TO LOWERING SNOW LEVELS...WHILE COLD AIR DAMMING EAST OF
   THE FRONT RANGE WILL EVENTUALLY LEAD TO SUBFREEZING TEMPERATURES
   ALONG THE LEE OF THE ROCKIES...PARTICULARLY IN NERN CO/SERN WY.
   RECENT OBSERVATIONS AT LARAMIE AND CHEYENNE ARE REPORTING
   SNOWFALL...INDICATING SNOW LEVELS AROUND 6-7 KFT. THE COOLER AIR
   MASS WILL GRADUALLY DEVELOP SWWD. OTHER SITES CONTINUE TO REPORT
   PLUMMETING TEMPERATURES...CONFIRMING LOWERING SNOW LEVELS. GIVEN
   DEEP LAYER MOISTENING IN ASSOCIATION WITH A MODIFIED PACIFIC AIR
   MASS IN ADDITION TO IMPLIED CONVECTIVE RATES WITH LIGHTNING RECENTLY
   REPORTED OVER THE FRONT RANGE...HEAVY SNOWFALL WITH RATES NEAR 1-2
   INCH AN HOUR CAN BE EXPECTED LATE TONIGHT INTO THE EARLY MORNING.
   
   ..HURLBUT.. 10/25/2011
   
   
   ATTN...WFO...PUB...BOU...CYS...GJT...
   
   LAT...LON   41420706 42020606 41670423 40900357 39930427 39320500
               39140594 39250703 39720728 41420706