MESOSCALE DISCUSSION 1778
   NWS STORM PREDICTION CENTER NORMAN OK
   0621 PM CDT TUE AUG 04 2009
   
   AREAS AFFECTED...PORTIONS SRN MO...EXTREME SERN KS...EXTREME NRN
   AR...EXTREME NERN OK...WRN/CENTRAL KY...WRN-MIDDLE TN...EXTREME NRN
   AL.
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 658...
   
   VALID 042321Z - 050115Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 658
   CONTINUES.
   
   ANOTHER WW WILL BE ISSUED SHORTLY FOR MORE OF MIDDLE/WRN TN AND
   PERHAPS NRN AL.  MAIN SVR CONCERN WILL REMAIN DAMAGING WIND WITH
   INCREASINGLY WELL-ORGANIZED COMPLEX NOW MOVING SEWD APPROXIMATELY 30
   KT FROM LOWEST OH RIVER VALLEY ACROSS PORTIONS WRN KY.
   
   THIS COMPLEX SHOULD TRACK SEWD ALONG AND W OF OUTFLOW BOUNDARY
   RELATED TO COLD POOL DISCUSSED IN MCD 1776.  FOREGOING/INFLOW-LAYER
   AIR MASS TOWARD MID TN AND NRN AL WILL REMAIN FAVORABLE FOR ANOTHER
   FEW HOURS...AS RICH LOW LEVEL MOISTURE HELPS TO KEEP EFFECTIVE
   INFLOW PARCELS ROOTED AT OR VERY NEAR SFC...WITH MLCAPE REMAINING
   1500-2500 J/KG SW OF OUTFLOW BOUNDARY.  BUOYANCY SHOULD DIMINISH
   WITH TIME AND WITH SWD EXTENT S OF ROUGHLY TN/AL STATE LINE WHERE
   LOW LEVEL MOISTURE AND MID-UPPER LEVEL LAPSE RATES EACH DIMINISH. 
   LOW LEVEL FLOW AND DEEP-LAYER SHEAR ALSO WEAKEN WITH SWD EXTENT.
   
   FARTHER W...RISING HEIGHTS AND STRONGER CAPPING CAST CONSIDERABLE
   UNCERTAINTY ON CONVECTIVE POTENTIAL ALONG/AHEAD OF SFC COLD
   FRONT...ESPECIALLY NOW THAT DIURNAL WARMING HAS PEAKED AND SFC
   DIABATIC COOLING WILL LEAD TO GREATER MLCINH.
   
   ..EDWARDS.. 08/04/2009
   
   
   ATTN...WFO...LMK...OHX...HUN...PAH...MEG...LSX...LZK...SGF...
   TSA...
   
   LAT...LON   37099505 37329307 38089041 37648937 37478853 37598760
               36928705 35618645 34858709 35438936 35979041 36469485
               37099505