MESOSCALE DISCUSSION 2251
   NWS STORM PREDICTION CENTER NORMAN OK
   0156 PM CDT WED OCT 12 2011
   
   AREAS AFFECTED...NORTH CENTRAL-NERN LA INTO WEST CENTRAL-SWRN MS
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 121856Z - 122000Z
   
   TSTMS WILL CONTINUE TO INCREASE IN COVERAGE ACROSS NORTH
   CENTRAL-NERN LA THIS AFTERNOON SPREADING EWD INTO WEST CENTRAL-SWRN
   MS.  AREAL COVERAGE OF ANY ATTENDANT SEVERE WEATHER THREAT IS
   EXPECTED TO REMAIN LIMITED WHICH PRECLUDES THE NEED FOR A WW AT THIS
   TIME.  HOWEVER...IF ACTIVITY SHOWS SIGNS OF COLD POOL DEVELOPMENT/
   INCREASED WIND THREAT...THEN A WW WOULD NEED TO BE CONSIDERED.
   
   EARLY AFTERNOON OBJECTIVE ANALYSIS SHOWED THE AIR MASS ACROSS LA
   INTO SWRN-WEST CENTRAL MS IS MARGINALLY-MODERATELY UNSTABLE /MLCAPE
   500 TO AROUND 1000 J PER KG/.  REGIONAL RADAR IMAGERY INDICATED AN
   INCREASE IN TSTM DEVELOPMENT OVER NRN LA SINCE 1745Z...WITH THIS
   ACTIVITY BEING AIDED BY FORCING FOR ASCENT ATTENDANT TO A SHORTWAVE
   TROUGH MOVING EWD THROUGH THE LOWER MS VALLEY THIS AFTERNOON.  IN
   ADDITION...WEAK WAA IN THE 850-700 MB LAYER IS LIKELY AIDING IN THIS
   DEVELOPMENT.
   
   THE SOMEWHAT MARGINAL AVAILABLE INSTABILITY AND WEAKER DEEP LAYER
   SHEAR OVER NRN LA TO WRN MS ARE TENDING TO RESULT IN WEAKER UPDRAFTS
   WITH MINIMAL ORGANIZATION.  ALTHOUGH STORMS WILL CONTINUE TO DEVELOP
   AND SPREAD EWD INTO MS THIS AFTERNOON...THE MARGINAL CAPE/SHEAR
   PARAMETER SPACE SUGGESTS THE SEVERE WEATHER THREAT WILL LIKELY BE
   ISOLATED.  MEANWHILE...A SURFACE RIDGE EXTENDING WWD FROM AL INTO MS
   IS MAINTAINING A MORE STABLE AIR MASS AS EVIDENT BY THE EXTENSIVE
   CLOUD SHIELD.  THUS...EVEN IF STORMS COULD BECOME ORGANIZED OVER
   NERN LA...THE SLOW DIMINISHING TREND IN THE WRN EXTENT OF THE CLOUD
   SHIELD WILL LIKELY LIMIT THE AREAL COVERAGE FOR ANY SUBSTANTIAL
   SEVERE WEATHER THREAT.
   
   ..PETERS.. 10/12/2011
   
   
   ATTN...WFO...JAN...LIX...LCH...SHV...
   
   LAT...LON   31329332 32329262 32979200 33189100 33089018 32198996
               31069025 31029172 31089315 31329332