MESOSCALE DISCUSSION 1783
   NWS STORM PREDICTION CENTER NORMAN OK
   0218 AM CDT WED AUG 05 2009
   
   AREAS AFFECTED...NERN AR THROUGH SWRN TN AND NRN MS
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 663...
   
   VALID 050718Z - 050815Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 663
   CONTINUES.
   
   THREAT FOR ISOLATED STRONG WIND GUSTS AND MARGINALLY SEVERE HAIL
   WILL PERSIST MAINLY ACROSS NRN AND NERN AR NEXT COUPLE HOURS. VERY
   HEAVY RAIN WITH RATES LOCALLY IN EXCESS OF 1 INCH PER HOUR ALSO
   REMAINS LIKELY. HOWEVER...A GRADUAL DECREASE IN OVERALL SEVERE
   THREAT IS EXPECTED THIS MORNING...AND REMAINING PARTS OF WW 663 WILL
   PROBABLY BE ALLOWED TO EXPIRE AT 08Z.
   
   EARLY THIS MORNING A CONVECTIVE OUTFLOW BOUNDARY EXTENDS FROM NRN MS
   NWWD THROUGH NERN AR. SOUTH OF THIS BOUNDARY...THE ATMOSPHERE
   REMAINS MODERATELY UNSTABLE /MUCAPE FROM 1500-2500 J/KG/ WITH THE
   STRONGER INSTABILITY AND STEEPER LAPSE RATES LOCATED ACROSS AR.
   STORMS HAVE WEAKENED ACROSS WRN TN AND HAVE BECOME ELEVATED WELL
   NORTH OF THE OUTFLOW BOUNDARY. STRONGER STORMS SHOULD PERSIST NEXT
   COUPLE HOURS ACROSS NERN AR WHERE LIFT IS MAXIMIZED IN ASSOCIATION
   WITH 30 KT SWLY BOUNDARY LAYER WINDS INTERACTING WITH SWD MOVING
   OUTFLOW BOUNDARY AND WHERE STEEPER MID LEVEL LAPSE RATES EXIST. LOW
   LEVEL WINDS ARE FORECAST TO VEER AND WEAKEN IN WAKE OF IMPULSE
   DROPPING SEWD INTO THE TN VALLEY...AND THIS COULD RESULT IN A
   GRADUAL DECREASE IN LIFT ALONG THE GUST FRONT LATER THIS MORNING. IN
   THE MEANTIME...STORMS DEVELOPING ALONG SWD THROUGH NERN AR MAY
   REMAIN CAPABLE OF PRODUCING ISOLATED MARGINALLY SEVERE HAIL AND
   STRONG WIND GUSTS.
   
   ..DIAL.. 08/05/2009
   
   
   ATTN...WFO...MEG...LZK...SGF...
   
   LAT...LON   36579240 35989099 35218989 34478909 34279040 34879093
               35569146 36029238 36489316 36579240