MESOSCALE DISCUSSION 0493
   NWS STORM PREDICTION CENTER NORMAN OK
   0217 AM CDT FRI APR 17 2009
   
   AREAS AFFECTED...PARTS OF SERN WY / NRN CO FRONT RANGE FOOTHILLS AND
   ADJACENT HIGH PLAINS
   
   CONCERNING...HEAVY SNOW 
   
   VALID 170717Z - 171115Z
   
   INTERMITTENT HEAVY SNOWFALL RATES UP TO 1 INCH/HR MAY DEVELOP AS
   EARLY AS 09-12Z IN AREAS IMMEDIATELY ADJACENT TO CO FOOTHILLS NEAR/W
   OF THE I-25 CORRIDOR AS CHANGEOVER OCCURS.
   
   LATEST SURFACE ANALYSIS SHOWS A 1007 MB SURFACE LOW INVOF NERN NM
   WITH A N-S ORIENTED STATIONARY FRONT ALONG THE CO FRONT RANGE THEN
   EXTENDING NEWD TOWARDS THE NEB SANDHILLS.  LATE EVENING SURFACE
   TEMPS HAVE GENERALLY HELD IN THE LOWER TO MIDDLE 30S F OVER THE MCD
   AREA TO THE W OF STATIONARY FRONT...WHEREAS LOCALES FURTHER N OVER
   SERN WY ARE AOB FREEZING WITH 1-2 INCH/HR SNOWFALL RATES REPORTED
   NEAR LAR DURING THE EVENING HRS.  
   
   WATER VAPOR IMAGERY SHOWS A MID-LEVEL VORTICITY MAXIMUM AND
   ATTENDANT DRYSLOT MOVING NWD FROM NERN NM TOWARDS E-CNTRL CO. 
   INCREASING UVV/S ASSOCIATED WITH THIS FEATURE ALONG WITH LOW-MID
   LEVEL FRONTOGENESIS AND UPSLOPE CONTRIBUTION WILL SUPPORT FOCUSED
   ASCENT ACROSS THE REGION THROUGH MID-MORNING FRI.  LATEST FORECAST
   SOUNDING MODEL SUITE SUGGESTS THERMODYNAMIC PROFILES SUPPORTIVE OF A
   RAIN TO SNOW CHANGEOVER BEGINNING GENERALLY AS EARLY AS THE 09-12Z
   PERIOD AS HEAVIER PRECIP RATES SHIFT S FROM SERN WY INTO CO. 
   STEEPENING LAPSE RATES ASSOCIATED WITH AFOREMENTIONED MID-LEVEL
   FEATURE AND OROGRAPHICAL FORCED ASCENT...MAY RESULT IN
   CONVECTIVELY-ENHANCED PRECIP/SNOW RATES UP TO 1 INCH/HR WITH
   LOCALIZED 2 INCH/HR POSSIBLE IN THE FOOTHILLS DURING THE MORNING
   HRS.
   
   ..SMITH.. 04/17/2009
   
   
   ATTN...WFO...PUB...BOU...
   
   LAT...LON   39900559 40840542 40840500 39960494 39200466 38780487
               38760520 39110539 39900559