MESOSCALE DISCUSSION 0557
   NWS STORM PREDICTION CENTER NORMAN OK
   0623 PM CDT SUN APR 24 2011
   
   AREAS AFFECTED...PORTIONS WRN/NRN AR...SERN OK...MO BOOT-HEEL...NWRN
   TN.
   
   CONCERNING...TORNADO WATCH 192...197...
   
   VALID 242323Z - 250130Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 192...197...CONTINUES.
   
   SVR TSTMS ARE EXPECTED TO MOVE EWD OUT OF NERN AR INTO MO BOOT-HEEL.
    COUNTIES MAY BE ADDED TO NERN PORTIONS WW 192 IN ADVANCE OF THAT
   ACTIVITY.  MEANWHILE...SVR POTENTIAL FCST TO INCREASE ACROSS WRN
   PORTIONS WW 192 AFTER SCHEDULED 00Z EXPIRATION.  ULTIMATELY...EITHER
   NEW WW COULD BE REQUIRED ACROSS PORTIONS AR E OF WW 197...OR
   COUNTIES ADDED TO WW 197...GIVEN INCREASING SVR THREAT FROM W-E THIS
   EVENING.
   
   SFC MESOANALYSIS SHOWS QUASISTATIONARY OUTFLOW BOUNDARY BETWEEN
   BNA-BWG...ALIGNED WSWWD TO WWD ACROSS NRN TIER TN COUNTIES TO MO
   BOOT-HEEL.  SVR TSTMS OVER NERN AR WILL CONTINUE MOVING ALONG AND N
   OF THIS BOUNDARY...WHERE LOW-LEVEL SRH AND STORM-RELATIVE INFLOW
   WILL BE ENHANCED.  ANOTHER OUTFLOW BOUNDARY EXTENDS SWWD FROM THAT
   ACTIVITY ACROSS WHITE/PULASKI/SALINE COUNTIES AR...MOVING SEWD 5-10
   KT BUT FCST TO DECELERATE TO QUASISTATIONARY IN NEXT COUPLE HOURS. 
   THAT PORTION OF THIS BOUNDARY WWD ACROSS LEFLORE COUNTY OK ALREADY
   HAS STALLED.  CORRESPONDING ZONE OF ENHANCED LOW-LEVEL VORTICITY/SRH
   WILL ACT TO CONCENTRATE EMBEDDED/SUPERCELLULAR AND/OR LEADING-EDGE
   QLCS TORNADO POTENTIAL ASSOCIATED WITH BAND OF SVR TSTMS NOW OVER
   ERN OK.  ADDITIONAL DEVELOPMENT...PERHAPS INCLUDING SUPERCELLS...IS
   POSSIBLE NEAR SFC LOW MOVING EWD FROM S-CENTRAL OK...AND WARM FRONT
   EXTENDING TO ITS ENE ACROSS COAL/SRN PITTSBURG/LATIMER COUNTIES TO
   INTERSECTION WITH OUTFLOW BOUNDARY OVER LEFLORE COUNTY.  VWP DATA
   AND MODIFIED RUC SOUNDINGS INDICATE 0-1 KM SRH 300-500 J/KG JUST N
   OF OUTFLOW BOUNDARY NEAR FSM...AND EFFECTIVE SHEAR MAGNITUDES 45-55
   KT SWD OVER ADJACENT WARM SECTOR.  STRONGEST BUOYANCY WILL REMAIN S
   OF BOUNDARY WITH MLCAPE IN 1500-2500 J/KG RANGE THROUGH AT LEAST
   01Z.  HOWEVER...SFC-BASED EFFECTIVE INFLOW PARCELS ARE EVIDENT 10-20
   NM N OF OUTFLOW BOUNDARY AND WARM FRONT.
   
   ..EDWARDS.. 04/24/2011
   
   
   ATTN...WFO...PAH...MEG...LZK...SGF...SHV...TSA...FWD...OUN...
   
   LAT...LON   33689457 33949685 34919579 35889329 36499276 36489017
               36468878 35608992 34759240 33689457