Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 201916
SWOMCD
SPC MCD 201915
NCZ000-VAZ000-KYZ000-TNZ000-GAZ000-ALZ000-202015-

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

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

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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