[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 112206
SWOMCD
SPC MCD 112206
NCZ000-TNZ000-VAZ000-KYZ000-112330-

MESOSCALE DISCUSSION 0449
NWS STORM PREDICTION CENTER NORMAN OK
0506 PM CDT THU APR 11 2013

AREAS AFFECTED...EASTERN TN AND IMMEDIATELY ADJACENT PORTIONS OF
NC/KY/VA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 112206Z - 112330Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...A WATCH MAY BE NEEDED FOR EASTERN TN AND PERHAPS
IMMEDIATELY ADJACENT PARTS OF NC/KY/VA FOR AN INCREASING SEVERE
THREAT THIS EVENING...WITH DAMAGING WINDS AND SOME TORNADO THREAT.

DISCUSSION...A RELATIVELY WELL-ORGANIZED QUASI-LINEAR CONVECTIVE
SYSTEM CONTINUES TO STEADILY PROGRESS EAST-NORTHEASTWARD /GENERALLY
35-40 KT/ ACROSS NORTH-CENTRAL/NORTHEAST AL...NOW EAST OF I-65 AND
NEAR THE HUNTSVILLE AREA AS OF 2145Z...AND EAST-CENTRAL TN. THIS
INCLUDES SOME SEMI-DISCRETE STORMS/POSSIBLE SUPERCELLS IMMEDIATELY
AHEAD OF THE QLCS. THIS ACTIVITY...THE QLCS AND POSSIBLE
LINE-LEADING SUPERCELLS...IS EXPECTED TO CONTINUE TO PROGRESS INTO
EASTERN TN/FAR WESTERN NC AND SURROUNDING AREAS THROUGH EARLY
EVENING. SCENARIO MAY BE INFLUENCED ON THE LARGE SCALE BY A
NORTHEAST-ADVANCING SHORTWAVE TROUGH/JET STREAK APPROACHING THE TN
VALLEY TONIGHT AND CORRESPONDING OHIO VALLEY SURFACE
CYCLOGENESIS...ALONG WITH SOME EASTWARD ACCELERATION OF THE UPSTREAM
COLD FRONT.

THE BOUNDARY LAYER IMMEDIATELY AHEAD OF THE QLCS IS CHARACTERIZED BY
MODESTLY HIGH TEMP-DEWPOINT SPREADS AS MUCH AS 15-20 F AS OF
22Z...WITH RELATIVELY WEAK LOW-LEVEL SHEAR CURRENTLY NOTED PER THE
MORRISTOWN WSR-88D VWP. HOWEVER...SURFACE T-TD SPREADS SHOULD
CONTINUE TO LOWER TOWARD/AFTER SUNSET...AND LOW-LEVEL SHEAR IS
LIKELY TO MARKEDLY INCREASE OVER THE NEXT FEW HOURS VIA A
STRENGTHENING SOUTHERLY LOW LEVEL JET...A TREND WELL NOTED IN
UPSTREAM OBSERVATIONS SUCH AS THE HUNTSVILLE WSR-88D VWP /AROUND 350
M2 PER S2 0-1 KM SRH/. IN ALL...BOUTS OF DAMAGING WINDS AND PERHAPS
A TORNADO OR TWO WILL BE A POSSIBILITY IN A SOUTHWEST-NORTHEASTWARD
CORRIDOR ACROSS EASTERN TN AND PERHAPS IMMEDIATELY SURROUNDING AREAS
INTO THIS EVENING.

..GUYER/CORFIDI.. 04/11/2013

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

ATTN...WFO...GSP...MRX...JKL...OHX...HUN...

LAT...LON   35068347 35028432 35098564 35188605 35948552 36458468
            36658332 35998261 35188288 35068347


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