MESOSCALE DISCUSSION 0177
   NWS STORM PREDICTION CENTER NORMAN OK
   1023 PM CST WED MAR 10 2010
   
   AREAS AFFECTED...FAR NERN LA / FAR SERN AR / CNTRL LA INTO W-CNTRL
   AL
   
   CONCERNING...TORNADO WATCH 25...
   
   VALID 110423Z - 110530Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 25 CONTINUES.
   
   THE THREAT FOR SEVERE STORMS CAPABLE OF HAIL...ISOLATED TORNADOES
   AND LOCALLY EXCESSIVE RAINFALL CONTINUES OVER WW AREA.
   
   THE ABSENCE OF CONVECTIVE DEVELOPMENT OVER MS PORTION OF WW MAY BE
   DUE IN PART TO THE PASSAGE OF A LOW AMPLITUDE PERTURBATION ACROSS
   SRN PARTS OF LA AND MS.  FORCING FOR ASCENT ASSOCIATED WITH THIS
   FEATURE IS...HOWEVER...IS CONTRIBUTING TO AN INCREASE IN STORM
   ORGANIZATION OVER EXTREME SERN PORTION OF WW AND POINTS TO THE E
   /I.E. SRN AL/.  HERE...AIR MASS IS RATHER MOIST WITH BOUNDARY LAYER
   DEWPOINTS IN THE LOWER 60S.  BUT...GENERALLY WEAK LAPSE RATES ARE
   LIMITING THE DEGREE OF CONVECTIVE INSTABILITY...PER RUC DIAGNOSTIC
   FIELDS.  NONETHELESS...CONVECTIVE TRENDS WILL CONTINUE TO BE
   MONITORED FOR FURTHER STORM ORGANIZATION IN THIS AREA.
   
   FARTHER W...A GRADUAL INCREASE IN REFLECTIVITY IS BEING NOTED NEAR
   HEZ WITHIN A ZONE OF LOW-LEVEL MOISTURE TRANSPORT ALONG SRN
   EXTENSION OF 40-45 KT LLJ AXIS.  03Z OBSERVED JAN SOUNDING INDICATES
   THAT AIR MASS REMAINS MODERATELY UNSTABLE WITH MLCAPE OF AROUND 1500
   J/KG.  WEAK CAPPING AT THE BASE OF A WELL-DEFINED EML IS LIKELY
   CONTRIBUTING TO THE ABSENCE OF DEEP MOIST CONVECTION THUS FAR.  
   
   HOWEVER...INCREASED FORCING FOR ASCENT FROM THE W...COUPLED WITH
   SUSTAINED...MOIST INFLOW INTO SHALLOW BAROCLINIC ZONE EXTENDING FROM
   NEAR OR S OF GWO TO S OF MEI MAY BE SUFFICIENT TO INITIATE STORMS
   WITHIN THE NEXT HOUR OR TWO.  OTHERWISE...EXTRAPOLATION OF QLCS OVER
   AR/NRN LA PLACES SYSTEM INTO WRM PART OF WW AREA BETWEEN 05-06Z. 
   MODERATELY STRONG LOW-LEVEL SHEAR AND LOW LCL HEIGHTS IN CONJUNCTION
   WITH THE MODERATE INSTABILITY INDICATE A CONTINUED THREAT FOR
   SUPERCELLS CAPABLE OF HAIL AND ISOLATED TORNADOES.
   
   ..MEAD.. 03/11/2010
   
   
   ATTN...WFO...BMX...MOB...JAN...
   
   LAT...LON   32129169 32939170 33659085 33528930 33278761 32138718
               31478796 31768899 31969026 32129169