MESOSCALE DISCUSSION 0814
   NWS STORM PREDICTION CENTER NORMAN OK
   0321 PM CDT WED MAY 13 2009
   
   AREAS AFFECTED...SRN/SERN KS AND NERN INTO CENTRAL/WRN OK
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 132021Z - 132145Z
   
   THUNDERSTORM INITIATION IS POSSIBLE BY 21-23Z OVER PORTIONS OF
   SRN/SERN KS AND NRN INTO CENTRAL/WRN OK. AREA IS BEING MONITORED FOR
   A WW.
   
   WATER VAPOR IMAGERY REVEALS A S/W TROUGH PROGRESSING ENE ACROSS THE
   CENTRAL/NRN PLAINS...ACCOMPANIED BY A 70+ KT MID LEVEL JET SAMPLED
   BY NLG PROFILER. MEANWHILE AT THE SURFACE...A COLD FRONT POSITIONED
   FROM ROUGHLY STJ TO ICT TO GAG AT 19Z IS FORECAST TO CONTINUE
   SAGGING SWD ACROSS SERN KS INTO NRN AND WRN OK THROUGH THE EVENING.
   STRONG SLY SURFACE WINDS OVER MUCH OF OK VEER TO SWLY ALONG THE
   FRONT...AND THEN NLY IN ITS WAKE...RESULTING IN STRONG LOW LEVEL
   CONVERGENCE. TEMPERATURES AHEAD OF THE COLD FRONT HAVE WARMED INTO
   THE MID 80S TO AROUND 90 DURING THE AFTERNOON...AND SURFACE
   DEWPOINTS RESIDE IN THE MID TO UPPER 60S. MODIFIED 18Z OUN SOUNDING
   FOR A TEMPERATURE OF 90 AND DEWPOINT IN THE UPPER 60S YIELDS OVER
   3500 J/KG OF MLCAPE. HOWEVER...A WARM CAPPING INVERSION STILL
   RESIDES NEAR 700 MB...EVIDENT BY STABLE CUMULUS FIELD IN VISIBLE
   SATELLITE IMAGERY. SHORT TERM DETERMINISTIC AND ENSEMBLE FORECAST
   GUIDANCE INDICATES THAT COMBINATION OF LARGE SCALE ASCENT WITH UPPER
   WAVE PASSING TO THE NORTH ALONG WITH FRONTAL CONVERGENCE WILL
   ERODE/LIFT THE CAPPING INVERSION BY 23Z...RESULTING IN INCREASING
   PROBABILITY OF THUNDERSTORM INITIATION FROM SERN/SRN KS INTO NRN/WRN
   OK.
   
   CONVECTIVE MODE ALONG FRONTAL BOUNDARY FROM MO INTO SERN/SRN KS AND
   NRN OK IS EXPECTED TO TRANSITION TOWARD LINEAR RATHER QUICKLY
   THROUGH THE EVENING...WHILE THE POTENTIAL FOR SLIGHTLY MORE DISCRETE
   ACTIVITY MAY EXIST OVER WRN OK. THE COMBINATION OF VERY STEEP MID
   LEVEL LAPSE RATES/LARGE CAPE AND EFFECTIVE BULK SHEAR AROUND 30-40
   KT INVOF THE FRONT MAY FAVOR SUPERCELL STORM STRUCTURES
   INITIALLY...POSING A THREAT OF LARGE-VERY LARGE HAIL ALONG WITH
   ISOLATED TORNADOES. HOWEVER...STRONG FRONTAL FORCING WILL FAVOR
   STORM TYPE TRANSITION TOWARD BOWS AND LEWPS WITHIN A FEW HRS AFTER
   INITIATION...RESULTING IN AN INCREASING THREAT FOR DAMAGING WIND
   GUSTS.
   
   ..GARNER.. 05/13/2009
   
   
   ATTN...WFO...SGF...EAX...TSA...TOP...ICT...OUN...DDC...
   
   LAT...LON   35329645 36219500 37519476 38479523 38429653 36869934
               36049985 35299975 34809898 34949787 35329645