MESOSCALE DISCUSSION 0437
   NWS STORM PREDICTION CENTER NORMAN OK
   1229 PM CDT FRI APR 15 2011
   
   AREAS AFFECTED...ERN MO / SWRN IL / FAR WRN KY / WRN TN / NERN AR /
   NRN MS
   
   CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 
   
   VALID 151729Z - 151830Z
   
   A TORNADO WATCH IS LIKELY IN THE NEXT HR OR SO ACROSS ERN MO / SWRN
   IL / WRN KY AS STORMS ARE FORECAST TO INITIATE BY EARLY AFTERNOON
   FIRST ACROSS THE MO/MS RIVER CONFLUENCE AREA.  FARTHER S STORMS ARE
   EXPECTED TO DEVELOP N TO S AS A COLD FRONT PUSHES EWD ACROSS NERN AR
   / WRN TN.  THIS WILL LIKELY REQUIRE AN ADDITIONAL TORNADO WATCH BY
   19-20Z.  IN ADDITION TO AN ISOLD TORNADO THREAT ACROSS THE SRN HALF
   OF THE REGION...LARGE TO VERY LARGE HAIL MAY ACCOMPANY THE STRONGER
   UPDRAFTS.
   
   RECENT SURFACE ANALYSIS AND SATELLITE TRENDS SHOW A DESTABILIZING
   WARM SECTOR THE MS VALLEY WHERE A TONGUE OF MID-UPPER 50 DEWPOINTS
   IS ADVECTING INTO THE ST LOUIS AREA.  MORE VIGOROUS BUILDUP IN THE
   CU FIELD HAS BEEN NOTED IN THIS REGION...WHERE BREAKS IN CLOUD COVER
   ARE LEADING TO A DESTABILIZING AIRMASS NEAR AND N OF THE I-70
   CORRIDOR IN ERN MO.  THIS TREND WILL CONTINUE AND LEAD TO STORM
   DEVELOPMENT IN THE NEXT HOUR OR TWO AS A PV ANOMALY NOTED ON WV
   IMAGERY OVER SERN OK/SWRN AR IS FORECAST TO RAPIDLY MOVE NEWD
   TOWARDS THE REGION DURING THE AFTERNOON.  STRONG VERTICAL SHEAR
   PROFILES WITHIN A STEEPENING LAPSE RATE ENVIRONMENT WITH TIME WILL
   SUPPORT SUPERCELLS CAPABLE OF LARGE HAIL/DMGG WINDS/ISOLD TORNADOES
   AS THE ACTIVITY ORGANIZES AND MATURES.  RECENT CONVECTIVE ALLOWING
   MODEL DATA SHOW STORMS INITIALLY DEVELOPING FIRST OVER ERN MO AND
   MOVE NNE INTO SWRN IL...WITH ADDITIONAL DEVELOPMENT LIKELY FARTHER S
   OVER SERN MO/NERN AR/WRN TN/NRN MS BY THE EARLY TO MID AFTERNOON
   HRS.
   
   ..SMITH.. 04/15/2011
   
   
   ATTN...WFO...HUN...PAH...ILX...MEG...LSX...DVN...
   
   LAT...LON   34479026 37759085 39209200 39899221 40209186 40449075
               40148979 39298892 37418845 34988815 34378856 34168981
               34479026