MESOSCALE DISCUSSION 0436
   NWS STORM PREDICTION CENTER NORMAN OK
   1028 AM CDT FRI APR 15 2011
   
   AREAS AFFECTED...PORTIONS MS...NERN LA...CENTRAL/SRN AL.
   
   CONCERNING...TORNADO WATCH 140...
   
   VALID 151528Z - 151730Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 140 CONTINUES.
   
   CONTINUE WW ALONG AND S OF QUASI-LINEAR CONVECTIVE SYSTEM DELINEATED
   BELOW.  PER COORD W/MOB...PERRY/GEORGE/GREENE COUNTIES MS ARE BEING
   ADDED TO WW AND MOBILE/WASHINGTON/CLARKE COUNTIES AL.  ADDITIONAL WW
   MAY BE REQUIRED DURING NEXT FEW HOURS ACROSS PORTIONS CENTRAL/SRN AL
   AS WELL.
   
   15Z SFC MESOANALYSIS AND CLOUD LINES IN VIS IMAGERY EACH INDICATE
   COLD FRONT FROM MO OZARKS SSEWD TO NEAR MLU...THEN SWWD TO NEAR HOU.
    COLD FRONT WILL CONTINUE TO MOVE EWD ACROSS LA AND INTO NWRN
   MS...PRECEDED BY CONFLUENCE ZONE ANALYZED INITIALLY NEAR
   TVR...HEZ...BTR...PTN LINE.  CONFLUENCE LINE ALSO IS EXPECTED TO
   SHIFT EWD ACROSS SERN LA AND SRN MS.  RELATIVELY VEERED SFC FLOW
   BETWEEN CONFLUENCE LINE AND COLD FRONT SHOULD MAKE WIND PROFILES
   MORE UNIDIRECTIONAL WITH HEIGHT AND FOSTER MORE LINEAR MODE FOR
   CONVECTION FORMING ALONG COLD FRONT.  MEANWHILE...SLY/SSELY WINDS
   BETWEEN CONFLUENCE LINE AND WARM FRONT WILL CONTRIBUTE MORE ENLARGED
   HODOGRAPHS AND 300-500 J/KG EFFECTIVE SRH...FAVORING MORE DISCRETE
   SUPERCELL/TORNADO POTENTIAL IN THAT SECTOR.  THIS INCLUDES CELLS
   OVER SERN MS/SWRN AL...AS WELL AS PRE COLD-FRONTAL CONVECTION NEAR
   MS RIVER MOVING E OF CONFLUENCE LINE.  THIS SECTOR WILL BE
   CHARACTERIZED ALSO BY MLCAPE INCREASING TO NEAR 2000 J/KG THROUGH
   18Z.  VIS IMAGERY ALSO INDICATES DIFFERENTIAL HEATING BOUNDARY
   SHOULD BECOME MORE PRONOUNCED ALONG SRN FRINGE OF CLOUD PLUME
   EMANATING FROM MCS...I.E. FROM TALLADEGA AREA WSWWD TO NEAR MEI. 
   THIS COULD PROVIDE FOCUS FOR EVENTUAL INSTABILITY GRADIENT AND
   VORTICITY ENHANCEMENT FOR ANY SUPERCELLS TRACKING NEAR IT.
   
   PRIMARY QLCS...AS OF 15Z...WAS LOCATED FROM SHARKEY COUNTY MS OVER
   CBM...WHERE IT INTERSECTED SFC WARM FRONT...THEN NEWD OVER
   PROGRESSIVELY MORE STABLE BOUNDARY LAYER OVER NWRN AL AND MARSHALL
   COUNTY TN.  THAT SEGMENT OF QLCS SW OF WARM FRONT WILL CONTINUE TO
   POSE RISK OF DAMAGING GUSTS AND A FEW TORNADOES...ESPECIALLY WITH
   EMBEDDED MESOCIRCULATIONS/SUPERCELLS.  MS SEGMENT MIGHT RETREAT
   SLIGHTLY NWD.  SVR POTENTIAL IS FCST TO DIMINISH WITH NEWD EXTENT
   FROM WARM FRONT AS FOREGOING LAYER OF NEAR-SFC STATIC STABILITY
   DEEPENS...LESSENING POTENTIAL FOR SVR GUSTS TO PENETRATE TO SFC. 
   HOWEVER...WARM FRONT WILL LIFT NEWD ACROSS SRN/CENTRAL
   AL...COMBINING WITH SFC DIABATIC HEATING S OF DIFFERENTIAL-HEATING
   ZONE TO DESTABILIZE AIR MASS SIGNIFICANTLY THROUGH EARLY AFTERNOON. 
   THEREFORE ADDITIONAL WW MAY BE NEEDED E OF WW 140.
   
   ..EDWARDS.. 04/15/2011
   
   
   ATTN...WFO...BMX...HUN...MOB...MEG...JAN...LIX...LCH...SHV...
   
   LAT...LON   32059244 32559189 33268986 33818809 34968725 34908581
               33288639 32318613 31348625 30418670 30258795 30488839
               30759030 31049193 32059244