MESOSCALE DISCUSSION 0309
   NWS STORM PREDICTION CENTER NORMAN OK
   0740 PM CDT TUE MAR 29 2011
   
   AREAS AFFECTED...SERN AR...NRN LA...NRN/CNTRL MS
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 74...
   
   VALID 300040Z - 300215Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 74
   CONTINUES.
   
   ELEVATED THUNDERSTORMS...SOME EXHIBITING SUPERCELLULAR
   CHARACTERISTICS...WILL CONTINUE TO MOVE E/NEWD ACROSS SVR TSTM WATCH
   74 AS ISENTROPIC ASCENT ABOVE THE NEAR-SURFACE STABLE LAYER
   PERSISTS. THE MOST ROBUST CONVECTIVE DEVELOPMENT OVER THE NEXT
   COUPLE OF HOURS IS ANTICIPATED TO BE NEAR THE INTERSTATE 20
   CORRIDOR...WHICH MARKS THE CONFLUENCE OF 850-MB SLY FLOW
   TRANSPORTING MOISTURE NWD FROM THE GULF OF MEXICO AND MORE SWLY FLOW
   AHEAD OF AN APPROACHING FRONT PER RUC ANALYSIS OUTPUT AND REGIONAL
   PROFILER DATA.
   
   THE KJAN SOUNDING AT 00Z INDICATED 1779 J/KG OF CAPE FOR A PARCEL
   LIFTED FROM AROUND 850 MB...OWING....IN PART...TO STEEP LAPSE RATES
   OF 7 C PER KM IN THE 700-500-MB LAYER. EVEN STEEPER MID-LEVEL LAPSE
   RATES /8 C PER KM/ WERE FOUND UPSTREAM AT KLZK...DUE TO COLDER
   MID-LEVEL TEMPERATURES ASSOCIATED WITH THE MID-LEVEL SHORTWAVE
   TROUGH APPROACHING FROM THE PLAINS. THIS AMOUNT OF INSTABILITY WILL
   CONTINUE TO SUPPORT STRONG/DEEP UPDRAFTS THROUGH THE EVENING...WHICH
   WILL BE FURTHER ENHANCED BY EFFECTIVE BULK SHEAR MAGNITUDES OF 40 TO
   50 KT ACCORDING TO 00Z RUC ANALYSIS. GIVEN THE ELEVATED NATURE OF
   THE CONVECTION...LARGE HAIL WILL BE THE MAIN CONCERN...PARTICULARLY
   WITH ANY SUSTAINED SUPERCELLS /AS NOTED WITH THE STORMS CROSSING THE
   MS RIVER SOUTH OF VICKSBURG AND THE LEFT-MOVER APPROACHING THE
   JACKSON AREA/.
   
   ..COHEN.. 03/30/2011
   
   
   ATTN...WFO...MEG...JAN...SHV...
   
   LAT...LON   32288892 32039063 31699268 31789355 32109392 32829387
               32869289 33089183 33349126 33859061 34048980 33898852
               33098841 32288892