MESOSCALE DISCUSSION 1935
   NWS STORM PREDICTION CENTER NORMAN OK
   0218 AM CDT THU AUG 20 2009
   
   AREAS AFFECTED...PARTS OF CNTRL AND SERN MO ...FAR N-CNTRL AR AND
   SWRN IL
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 720...
   
   VALID 200718Z - 200845Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 720
   CONTINUES.
   
   AS OF 0705Z...REGIONAL RADAR DATA INDICATED THE LEADING EDGE OF A
   BOWING MCS EXTENDING FROM ST. LOUIS AND JEFFERSON COUNTIES IN
   E-CNTRL MO TO FULTON COUNTY INTO N-CNTRL AR.  SYSTEM MOTION WAS EWD
   AT AROUND 40 KT.  WHILE CURRENT ST. LOUIS VWP IS JUST BEGINNING TO
   SAMPLE THE KINEMATIC ENVIRONMENT ATTENDANT TO SYSTEM COLD POOL...THE
   CONWAY MO PROFILER IS LIKELY MORE REPRESENTATIVE... FEATURING 40 KT
   BELOW 1 KM AND A 60-65 KT WLY AIRSTREAM BETWEEN 2-3 KM AGL...PERHAPS
   ASSOCIATED WITH EVOLVING REAR INFLOW JET.
   
   LAPSE RATES HAVE WEAKENED WITHIN AMBIENT INFLOW AIR MASS OVER THE
   LOWER OH VALLEY.  BUT...SWLY 40-50 KT LLJ IS FORECAST TO DEVELOP
   NEWD THROUGH THE REGION BETWEEN 09-12Z...WHICH WILL SERVE TO ENHANCE
   LOW-LEVEL THETA-E ADVECTION INTO ONGOING MESOSCALE SYSTEM.  AS
   SUCH...THE THREAT FOR AT LEAST LOCALLY DAMAGING WIND GUSTS WILL
   CONTINUE ACROSS ERN PARTS OF WW AREA.  CONVECTIVE TRENDS WILL BE
   MONITORED FOR THE POSSIBILITY OF A DOWNSTREAM WW LATER THIS MORNING.
   
   ..MEAD.. 08/20/2009
   
   
   ATTN...WFO...PAH...LSX...SGF...
   
   LAT...LON   36579207 37949188 38679060 38878947 37938892 36978962
               36609069 36579207