[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 181934
SWOMCD
SPC MCD 181933
TNZ000-VAZ000-KYZ000-182100-

MESOSCALE DISCUSSION 0124
NWS STORM PREDICTION CENTER NORMAN OK
0133 PM CST WED FEB 18 2009

AREAS AFFECTED...CNTRL/ERN KY INTO MIDDLE/ERN TN

CONCERNING...TORNADO WATCH 23...

VALID 181933Z - 182100Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 23 CONTINUES.

PRIMARY SEVERE THREAT /I.E. LARGE HAIL...DAMAGING WINDS AND PERHAPS
A TORNADO OR TWO/ IS EXPECTED TO CONTINUE ACROSS ERN HALF OF WW AREA
THROUGH 21Z.  BASED ON EXTRAPOLATION OF CURRENT STORM MOTIONS...ERN
EXTENSION OF THIS THREAT MAY DEVELOP E OF WW AREA BY 2000-2030Z AND
AN ADDITIONAL WW MAY BE REQUIRED.

AS OF 1920Z...REGIONAL RADAR IMAGERY INDICATED A BAND OF SCATTERED
STRONG TO SEVERE TSTMS FROM KNOX COUNTY KY WSWWD TO WAYNE COUNTY KY
AND THEN MORE SWD THROUGH MIDDLE TN.  THE MOST INTENSE STORM /A
SUPERCELL/ WAS LOCATED AT THE INTERSECTION OF WHITE...PUTNAM AND
CUMBERLAND COUNTIES TN WITH AN ESTIMATED STORM MOTION OF 265/45 KT.

18Z BNA SOUNDING INDICATED THAT CONSIDERABLE WARMING IN THE BOUNDARY
LAYER HAD DESTABILIZED AIR MASS DESPITE THE MARGINAL MOISTURE
CONTENT WITH MLCAPE OF A FEW HUNDRED J/KG.  THIS SAME
DESTABILIZATION PROCESS IS NOW OCCURRING FURTHER E OVER THE
CUMBERLAND PLATEAU WHERE NOTABLE INCREASES IN BOUNDARY LAYER HEAT
AND MOISTURE ARE OCCURRING PER 3-HR CHANGE FIELDS.  VERTICAL SHEAR
REMAINS QUITE STRONG AND SUPPORTIVE OF ORGANIZED STORMS INCLUDING
SUPERCELLS ASSUMING SUFFICIENT INSTABILITY DEVELOPS TO MAINTAIN
ONGOING STORMS.  WHILE LARGE HAIL AND DAMAGING WIND GUSTS WILL BE
THE PRIMARY SEVERE THREATS...AN ISOLATED TORNADO REMAINS POSSIBLE
WITH THE MORE INTENSE SUPERCELLS.

..MEAD.. 02/18/2009

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

ATTN...WFO...RLX...MRX...JKL...LMK...OHX...HUN...

LAT...LON   35108687 36458559 37078417 37278297 37178251 36478255
            35568377 35118487 35038520 35108687

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