MESOSCALE DISCUSSION 1431
   NWS STORM PREDICTION CENTER NORMAN OK
   0527 PM CDT SAT JUL 04 2009
   
   AREAS AFFECTED...ERN AND SERN MO/FAR NERN AR/FAR SRN IL/WRN KY/WRN
   TN
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 547...
   
   VALID 042227Z - 042330Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 547
   CONTINUES.
   
   GIVEN DEGREE OF DOWNSTREAM INSTABILITY AND RECENT INCREASE IN
   FORWARD SPEED OF THE LINE OF TSTMS WITHIN WW 547...ADDITIONAL
   COUNTIES WITHIN WFO PAH/MEG MAY NEED TO BE ADDED OR A NEW WW MAY BE
   REQUIRED SOON.
   
   OBJECTIVE ANALYSES INDICATE AIR MASS DOWNSTREAM OF WW 547 INTO WRN
   KY/WRN TN HAS BECOME MODERATELY UNSTABLE GIVEN RICH LOW LEVEL
   MOISTURE /SURFACE DEWPOINTS IN THE UPPER 60S-LOWER 70S/ IN PLACE AND
   SURFACE HEATING.  THIS FAVORABLE THERMODYNAMIC ENVIRONMENT COMBINED
   WITH EFFECTIVE BULK SHEAR UP TO 50 KT ATTENDANT TO STRONG WNWLY MID
   LEVEL JET SPREADING ACROSS LOWER OH VALLEY WILL SUPPORT ADDITIONAL
   STORM ORGANIZATION AS ACTIVITY SPREADS EWD THIS EVENING.
   
   REGIONAL RADARS AND COOLING CLOUD TOPS ON IR SATELLITE IMAGERY WITH
   THE TSTM COMPLEX EXTENDING FROM FAR SRN IL THROUGH FAR SERN MO/NERN
   AR HAS INCREASED IN FORWARD SPEED TO 40 KT.  THIS INCREASE IN
   INTENSITY APPEARS TO BE LOCATED ALONG INTERSECTION OF THIS LINE OF
   STORMS WITH AN OUTFLOW BOUNDARY EXTENDING EWD THROUGH SRN KY.  A
   TORNADO THREAT IS ALSO POSSIBLE WITH ANY STORMS IN THE VICINITY OF
   THIS BOUNDARY WHERE 0-1 KM SHEAR IS 20-25 KT. 
   
   ISOLATED TSTMS LOCATED OVER MIDDLE TN APPEAR TO BE ELEVATED GIVEN
   STRONGER SURFACE BASED CINH...WITH HAIL BEING THE PRIMARY THREAT.
   
   ..PETERS.. 07/04/2009
   
   
   ATTN...WFO...LMK...OHX...PAH...MEG...LSX...
   
   LAT...LON   35789085 36679005 37468964 38218934 38278831 37828712
               36778657 35978684 35378735 35148819 35108937 35159000
               35789085