MESOSCALE DISCUSSION 0109
   NWS STORM PREDICTION CENTER NORMAN OK
   1107 AM CST FRI FEB 13 2009
   
   AREAS AFFECTED...ERN NEB AND WRN IA
   
   CONCERNING...HEAVY SNOW 
   
   VALID 131707Z - 132030Z
   
   SNOW WITH RATES OF 1-1.5 IN/HR ARE POSSIBLE OVER PORTIONS OF ERN NEB
   AND WRN IA...BUT OVERALL INTENSITY IS EXPECTED TO DECREASE AFTER
   21Z.
   
   WV IMAGERY SHOWS A PROGRESSIVE LOW AMPLITUDE MID LVL S/W TROUGH IS
   ENTERING ERN KS/SERN NEB...AND IS FORECAST TO MOVE INTO NRN MO/SRN
   IA BY 00Z/14. LOW LEVEL RESPONSE ALONG AND AHEAD OF THE UPPER WAVE
   IS RESULTING IN STRONG WAA ACROSS ERN NEB/WRN IA...EVIDENT BY
   STRONGLY VEERING WIND PROFILES PER REGIONAL VWP DATA. FURTHER WEST
   OVER CENTRAL-SRN NEB...MID LEVEL DEFORMATION OCCURRING ALONG A
   QUASI-MERIDIONAL THERMAL GRADIENT IS FAVORING STRONG FRONTOGENESIS.
   MODERATE TO HEAVY SNOWFALL HAS OCCURRED ALONG THESE FEATURES DURING
   THE MORNING...DUE TO STRONG ASCENT OCCURRING WITHIN A DEEPLY
   SATURATED ENVIRONMENT. RATES HAVE BEEN FURTHER ENHANCED BY STEEP MID
   LEVEL LAPSE RATES /7.1 C PER KM IN THE 700-500 MB LAYER...AS
   INDICATED BY THE 12Z TOP RAOB/ IMPINGING INTO THE SRN HALF OF NEB.
   
   SHORT TERM MODEL GUIDANCE INDICATES THAT THE MID LEVEL WAVE WILL
   WEAKEN THROUGH THE AFTERNOON. AS THIS OCCURS...850-700 MB CYCLONIC
   CIRCULATION WILL DISSIPATE...RESULTING IN A DECREASE IN LOW LEVEL
   WAA AND FRONTOGENETIC FORCING. THOUGH SNOWFALL RATES OF 1-1.5 IN/HR
   WILL BE POSSIBLE INTO THE AFTERNOON HOURS...A DECREASING TREND IN
   SNOWFALL INTENSITY IS ANTICIPATED AFTER 21Z.
   
   ..GARNER.. 02/13/2009
   
   
   ...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...DMX...EAX...FSD...OAX...GID...
   
   LAT...LON   40459558 40099731 40099844 40139906 40309940 40919925
               41429846 42029682 42339578 42539439 41949307 41339306
               40939367 40459558