[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 171859
SWOMCD
SPC MCD 171858
OHZ000-KYZ000-TNZ000-INZ000-172030-

MESOSCALE DISCUSSION 2171
NWS STORM PREDICTION CENTER NORMAN OK
1258 PM CST MON DEC 17 2012

AREAS AFFECTED...PORTIONS OF KY...MIDDLE TN...FAR SRN IND

CONCERNING...SEVERE THUNDERSTORM WATCH 683...

VALID 171858Z - 172030Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 683
CONTINUES.

SUMMARY...THE THREAT FOR SVR HAIL/WIND CONTINUES ACROSS SVR TSTM
WATCH 683.

DISCUSSION...A LINE OF SCATTERED LOW-TOPPED THUNDERSTORMS...
EXHIBITING MID-LEVEL MESOCYCLONES AT TIMES...EXTENDS FROM W OF
LOUISVILLE TO W OF BOWLING GREEN TO W OF NASHVILLE AS OF 1850Z.
THESE STORMS DEVELOPED ALONG A LOW-LEVEL CONFLUENCE AXIS...AND THE
LINE WILL CONTINUE TRACKING EWD AROUND 20-25 KT. A DOWNSTREAM
CORRIDOR OF INSOLATION...SUPPORTING UPPER 50S TO LOWER 60S TEMPS
AMIDST SEASONABLY ANOMALOUS LOWER 50S DEWPOINTS...IS SUPPORTING
MLCAPE VALUES OF 500-1000 J/KG PER MODIFIED FORECAST SOUNDINGS.
BROAD CAPE PROFILES...COMBINED WITH 30-45 KT OF DEEP SHEAR PER VWP
DATA...WILL CONTINUE TO SUPPORT INTENSE/ROTATING UPDRAFTS.
ACCORDINGLY...THE THREAT FOR SVR HAIL AND POSSIBLY SVR WIND WILL
INCREASE AS STORMS CROSS CNTRL KY DURING THE NEXT FEW HOURS. SFC
OBSERVATIONS SUGGEST THAT THESE STORMS HAVE DEPOSITED LITTLE IN THE
WAY OF A COLD POOL OWING TO NEGATIVE PRESSURE TENDENCIES UPSTREAM OF
THE LINE. AS SUCH...ADDITIONAL STRONG/SVR STORM DEVELOPMENT IS
FORECAST BEHIND THE LINE AS A MID-LEVEL ASCENT MAX APPROACHES. WHILE
LOW-LEVEL FLOW IS NOT PARTICULARLY STRONG...A TORNADO OR TWO CANNOT
BE RULED OUT WHERE LOW-LEVEL SHEAR IS MODESTLY ENHANCED ACROSS
MIDDLE TN AND S-CNTRL KY AND NEAR A STATIONARY FRONT LYING ALONG THE
OH RIVER.

..COHEN.. 12/17/2012

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

ATTN...WFO...RLX...MRX...JKL...ILN...LMK...OHX...IND...PAH...
MEG...

LAT...LON   35768506 35778829 38808626 38808293 35768506



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