MESOSCALE DISCUSSION 0500
   NWS STORM PREDICTION CENTER NORMAN OK
   1249 PM CDT FRI APR 17 2009
   
   AREAS AFFECTED...PORTIONS OF SERN CO...SW KS...AND THE OK PANHANDLE
   
   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 
   
   VALID 171749Z - 171915Z
   
   LOW TOP THUNDERSTORMS POSING A THREAT OF MAINLY LARGE HAIL AND
   PERHAPS A BRIEF TORNADO ARE POSSIBLE OVER PORTIONS OF SERN CO...SW
   KS...AND THE OK PANHANDLE. CONVECTIVE TRENDS WILL BE MONITORED FOR A
   POSSIBLE WW.
   
   UPR AIR AND SATELLITE IMAGERY COMBINED WITH SUBJECTIVE SURFACE
   ANALYSIS SHOW A NEARLY VERTICALLY STACKED CYCLONE OVER NRN-NERN NM.
   AN OCCLUDED SURFACE FRONT WAS OBSERVED EXTENDING E-SEWD AWAY FROM
   THE LOW...POSITIONED OVER SERN CO INTO THE OK/TX PANHANDLE. E-SELY
   LOW LVL FLOW N OF THE FRONT HAS MAINTAINED UPR 40S
   DEWPOINTS...THOUGH CLOUD COVER HAS RESULTED IN COOL /LOW 50S/
   TEMPERATURES. HOWEVER...RAPID CLEARING ACCOMPANIED BY BOUNDARY LAYER
   DESTABILIZATION IS OCCURRING IMMEDIATELY S OF THE FRONT. MODEST
   CONVECTIVE INSTABILITY IS DEVELOPING WITHIN THIS TRANSITION ZONE
   /AROUND 500 J PER KG OF MLCAPE/...WITH A SLIGHT INCREASE IN CAPE
   POSSIBLE THROUGH THE EARLY TO MID AFTERNOON AS HEATING INCREASES
   WITHIN THE CLEAR SLOT. AS A RESULT...A BROKEN LINE OF STORMS HAS
   RECENTLY DEVELOPED FROM NEAR LHX TO 40 NE OF SPD TO LBL.
   
   AS INSTABILITY INCREASES DURING THE NEXT FEW HOURS...THE THREAT FOR
   LARGE HAIL IS EXPECTED TO INCREASE AS WELL...GIVEN THE COLD MID LVL
   AIRMASS AND STEEP LAPSE RATE ENVIRONMENT. VERTICAL WIND SHEAR IS NOT
   FORECAST TO BE PARTICULARLY STRONG /EFFECTIVE BULK SHEAR ON THE
   ORDER OF 25-35 KT...EFFECTIVE SRH AOB 100 M2 PER S2/.
   HOWEVER...SURFACE WINDS CHANGE FROM SSW TO ESE ALONG THE FRONTAL
   BOUNDARY /RESULTING IN STRONG AMBIENT VERTICAL VORTICITY/...AND 0-3
   KM CAPE IS FORECAST TO APPROACH 100-150 J/KG...WHICH SUGGESTS THAT A
   SMALL THREAT FOR A BRIEF TORNADO ALSO EXISTS.
   
   ..GARNER.. 04/17/2009
   
   
   ATTN...WFO...DDC...GLD...AMA...PUB...BOU...
   
   LAT...LON   38320431 38810375 38890284 38780208 38280130 37460081
               36980076 36640082 36620122 37130152 37640205 37990267
               38050318 37890435 38320431