MESOSCALE DISCUSSION 2004
   NWS STORM PREDICTION CENTER NORMAN OK
   0240 PM CDT THU AUG 18 2011
   
   AREAS AFFECTED...SRN IL...SWRN IND...WRN KY...FAR SERN MO
   
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 
   
   VALID 181940Z - 182145Z
   
   WHILE A FEW STORMS COULD CONTAIN GUSTY WINDS THIS AFTERNOON...AND AN
   ISOLATED INSTANCE OR TWO OF DMGG WINDS CANNOT BE RULED OUT...THE SVR
   THREAT IS EXPECTED TO REMAIN MINIMAL AND THE ISSUANCE OF A WW IS
   UNLIKELY.
   
   SFC MESOANALYSIS AT 19Z DEPICTS A WEAK FRONT DRAPED ACROSS PORTIONS
   OF NRN IND/IL INTO W-CNTRL IL AND SRN MO...WITH AN ATTENDANT MESOLOW
   OVER E-CNTRL MO. EAST OF THE MESOLOW...ISOLATED TO WIDELY SCATTERED
   CONVECTION HAS EVOLVED FROM A DISORGANIZED BAND OF AGITATED CUMULUS
   GROWTH...COINCIDENT WITH AN AXIS OF LOCALLY ENHANCED LOW-LEVEL
   CONVERGENCE. HOWEVER...WITH FLOW BELOW 1 KM AGL AOB 10 KT PER
   EVANSVILLE/PADUCAH VWP DATA AND SFC OBS...THE CONVERGENCE IS RATHER
   WEAK. NEVERTHELESS...AMPLE INSOLATION HAS SUPPORTED TEMPERATURES
   CLIMBING INTO THE UPPER 80S TO LOWER 90S AMIDST DEWPOINTS IN THE
   LOWER/MIDDLE 70S...ALLOWING THE AIR MASS TO BECOME MODERATELY TO
   VERY UNSTABLE. RUC FORECAST SOUNDINGS SUGGEST THAT ANY SUBSTANTIAL
   TROPOSPHERIC FLOW IS RELEGATED TO THE UPPER LEVELS /E.G. NWLY WINDS
   OF 50-60 KT BETWEEN 350 AND 200 MB/ SUPPORTING EFFECTIVE BULK SHEAR
   MAGNITUDES OF GENERALLY 30-45 KT. THIS COULD SUPPORT OCCASIONALLY
   ORGANIZED STORM STRUCTURES WITH GUSTY WINDS...AND AN ISOLATED
   INSTANCE OR TWO OF DMGG WINDS CANNOT BE RULED OUT GIVEN DCAPE VALUES
   AOA 1000 J/KG. HOWEVER NOTABLY WEAKER FLOW EXISTS IN THE LOW/MID
   LEVELS...WHICH SHOULD BE A MITIGATING FACTOR FOR A MORE SUBSTANTIAL
   SVR THREAT. FURTHERMORE...THE LACK OF MORE SALIENT FORCING
   MECHANISMS FOR ASCENT SHOULD LIMIT THE OVERALL THREAT FOR MORE
   ORGANIZED CONVECTION AND THE ATTENDANT SVR THREAT.
   
   ..COHEN.. 08/18/2011
   
   
   ATTN...WFO...LMK...IND...PAH...ILX...LSX...
   
   LAT...LON   36808776 36668952 36939054 37519042 38278933 39068833
               39018725 38478665 37408660 36808776