MESOSCALE DISCUSSION 0610
   NWS STORM PREDICTION CENTER NORMAN OK
   0913 PM CDT TUE APR 26 2011
   
   AREAS AFFECTED...PORTIONS ERN/NRN AR...NWRN MS...WRN-MIDDLE TN...WRN
   KY...EXTREME SERN MO....EXTREME SRN IL...EXTREME SWRN INDIANA.
   
   CONCERNING...TORNADO WATCH 217...221...
   
   VALID 270213Z - 270315Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 217...221...CONTINUES.
   
   PER COORD W/OHX WFO...A FEW MORE COUNTIES ARE BEING ADDED TO WW 217
   AHEAD OF MCS MOVING ENEWD OUT OF NRN MS/WRN TN...FOR NEAR-TERM
   COVERAGE.  THIS WW ULTIMATELY WILL BE REPLACED BEFORE SCHEDULED 03Z
   EXPIRATION...GIVEN THAT SVR THREAT IS EXPECTED TO PERSIST OVER MUCH
   OF LOWER-MID MS VALLEY REGION WELL INTO OVERNIGHT HOURS. THREAT
   INCLUDES TORNADOES AS WELL AS DAMAGING WIND.  DAMAGING HAIL ALSO IS
   STILL POSSIBLE FROM INDIVIDUAL SUPERCELLS.
   
   BOW ECHO ORGANIZING ACROSS NRN AR SHOULD PERSIST WELL NEWD OVER SERN
   MO TOWARD LOWER OH VALLEY REGION...AS IT MOVES GENERALLY ALONG AND S
   OF INSTABILITY/BAROCLINIC GRADIENT ASSOCIATED WITH FRONTAL ZONE. 
   NRN PORTION OF THIS ACTIVITY WILL BE ALIGNED STRONGLY ORTHOGONAL TO
   STRENGTHENING DEEP-LAYER WIND VECTORS...AND AS SUCH...BEARS
   INCREASING POTENTIAL FOR ORGANIZED WIND EVENT.  QLCS CIRCULATIONS
   ALSO MAY RESULT IN A FEW TORNADOES.  SE OF THAT BOW AND TRAILING
   SQUALL LINE...SUPERCELLS AND SMALLER BOWS MAY DEVELOP VIRTUALLY
   ANYWHERE WITHIN BROAD AREA OF PRECIP AND TSTMS THAT IS EVIDENT
   ACROSS ERN AR NEWD OVER WRN KY.  ALTHOUGH THIS ACTIVITY HAS REDUCED
   BUOYANCY...POCKETS OF FAVORABLE INSTABILITY REMAIN...BASED ON
   MODIFIED RAOBS AND RUC SOUNDINGS.  SFC-BASED PARCELS AND 500-1500
   J/KG MLCAPE ARE POSSIBLE THROUGH AT LEAST 06Z OVER PORTIONS AR..AS
   WELL AS WRN/CENTRAL KY AND WRN/MIDDLE TN AWAY FROM ONGOING MCS. 
   500-MB HEIGHT FALLS...ANALYZED AT 00Z JUST AHEAD OF TROUGH OVER OK
   AND N TX...WILL PIVOT OVER THIS REGION TONIGHT ALONG WITH TIGHTENING
   GRADIENTS ALOFT.  THEREFORE...FAVORABLE DEEP-LAYER SHEAR SHOULD
   REMAIN IN PLACE...WHILE LLJ MAINTAINS LARGE HODOGRAPHS.
   
   ..EDWARDS.. 04/27/2011
   
   
   ATTN...WFO...LMK...OHX...PAH...MEG...JAN...LZK...SGF...
   
   LAT...LON   33109207 34999207 34499372 35329211 36039183 36459190
               36799016 37838907 38408711 37658698 36498721 34938894
               33109207