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Mesoscale Discussion 1586
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   MESOSCALE DISCUSSION 1586
   NWS STORM PREDICTION CENTER NORMAN OK
   0215 PM CDT WED AUG 20 2014

   AREAS AFFECTED...SRN KY...MIDDLE AND ERN TN...ADJACENT SW VA/WRN NC
   AND SC/NRN GA AND AL

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 201915Z - 202015Z

   PROBABILITY OF WATCH ISSUANCE...40 PERCENT

   SUMMARY...TRENDS WILL CONTINUE TO BE MONITORED FOR UPSCALE
   CONVECTIVE GROWTH WHICH COULD NECESSITATE A SEVERE WEATHER WATCH. 
   OTHERWISE... SCATTERED...RELATIVELY DISORGANIZED...STRONG TO SEVERE
   STORM DEVELOPMENT CAPABLE OF PRODUCING LOCALLY SEVERE HAIL AND WIND
   GUSTS PROBABLY WILL CONTINUE THROUGH LATE AFTERNOON.

   DISCUSSION...SCATTERED VIGOROUS THUNDERSTORM DEVELOPMENT IS NOW WELL
   UNDERWAY ACROSS THE TENNESSEE VALLEY INTO SOUTHERN APPALACHIANS
   REGION.  THIS HAS BEEN SUPPORTED BY DESTABILIZATION ASSOCIATED WITH
   DAYTIME HEATING OF A SEASONABLY MOIST BOUNDARY LAYER /WITH SURFACE
   DEW POINTS IN THE 70S/.  BENEATH THE NOSE OF A PLUME OF MODESTLY
   STEEP MID-LEVEL LAPSE RATES ASSOCIATED WITH ELEVATED MIXED LAYER AIR
   ARCING EAST SOUTHEAST OF THE NORTH CENTRAL PLAINS...MIXED LAYER CAPE
   HAS BECOME QUITE LARGE...AND APPEARS ON THE ORDER OF 3000-4000+ J/KG
   ACROSS MUCH OF TENNESSEE AND SOUTHERN KENTUCKY INTO THE WESTERN
   SLOPES OF THE SOUTHERN APPALACHIANS.  

   ALTHOUGH MID/UPPER FORCING FOR UPWARD VERTICAL MOTION APPEARS
   GENERALLY WEAK...AND THE POSSIBLE INFLUENCE OF A CONVECTIVELY
   GENERATED SURFACE BOUNDARY NOW ADVANCING SOUTH OF THE OHIO RIVER
   REMAINS UNCLEAR AS IT CONTINUES SOUTHWARD THIS AFTERNOON...A
   CONSIDERABLE FURTHER INCREASE IN STORMS SEEMS LIKELY THROUGH 20-22Z.
   THIS SHOULD BE SUPPORTED BY LIFT ALONG NUMEROUS CONVECTIVE OUTFLOWS
   WHICH COULD BEGIN TO CONSOLIDATE AND SUPPORT UPSCALE CONVECTIVE
   GROWTH.  DEEP LAYER SHEAR IS NOT STRONG...BUT IT DOES NOT APPEAR OUT
   OF THE QUESTION THAT A BELT OF 30+ KT NORTHWESTERLY LOWER/MID
   TROPOSPHERIC FLOW MAY BE SUFFICIENT TO EVENTUALLY CONTRIBUTE TO THE
   EVOLUTION OF AN ORGANIZED CONVECTIVE SYSTEM CAPABLE OF PRODUCING A
   BROADER SCALE DAMAGING WIND THREAT.

   ..KERR/MEAD.. 08/20/2014


   ATTN...WFO...GSP...MRX...JKL...FFC...LMK...OHX...BMX...HUN...
   PAH...MEG...

   LAT...LON   37068809 37638594 37628476 37308344 36768287 35858280
               35218304 34548363 34188527 34628607 35688801 36148844
               37068809 

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Page last modified: August 20, 2014
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