[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 212118
SWOMCD
SPC MCD 212118
ILZ000-KYZ000-TNZ000-MOZ000-MSZ000-ARZ000-212245-

MESOSCALE DISCUSSION 2153
NWS STORM PREDICTION CENTER NORMAN OK
0318 PM CST WED NOV 21 2007

AREAS AFFECTED...EXTREME SRN IL...SERN MO...CNTRL/ERN AR

CONCERNING...TORNADO WATCH 734...

VALID 212118Z - 212245Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 734 CONTINUES.

TSTMS CONTINUE TO DEVELOP VCNTY THE COLD FRONT MOVING EWD ACROSS
SERN MO AND CNTRL AR LATE THIS AFTN.  LATEST MESOANALYSIS ALSO
INDICATES PRESENCE OF A WEAK PRE-FRONTAL TROUGH EXTENDING FROM NERN
AR SWWD TO THE EAST OF LITTLE ROCK.  THIS MAY SERVE AS A FOCUS FOR
ADDITIONAL TSTMS LATE THIS AFTN/EARLY EVENING AS STRONGER LARGE
SCALE ASCENT SPREADS EWD.

LZK VWP SUGGESTS THAT THERE WAS SUFFICIENT CROSS-COMPONENT DEEP
LAYER SHEAR WITH RESPECT TO THE FRONT TO MAINTAIN DISCRETE CELLS.
BUT...THE NUMBER OF STORMS INITIATING ALONG THE SYNOPTIC BOUNDARY
MAY EVENTUALLY RESULT IN EVOLUTION INTO SHORT LINE SEGMENTS.
IMPROVING BULK SHEAR WITH TIME DURING THE NEXT FEW HOURS WILL
MAINTAIN A SUPERCELL THREAT EMBEDDED WITHIN...HOWEVER.  PRIMARY SVR
THREATS WILL BE LARGE HAIL AND DMGG WIND GUSTS.  A DEVIANT STORM
MOTION WOULD RESULT IN AROUND 200 M2/S2 0-1KM SRH AND MAY SUPPORT A
TORNADO OR TWO.  THIS WILL ESPECIALLY BE TRUE IF STORMS CAN DEVELOP
EAST OF THE COLD FRONT.  OTHERWISE...STORMS MAY TEND TO BECOME
UNDERCUT BY THE SURGING COLD AIR...LESSENING THE TORNADO RISK.

GIVEN THAT THE PRIMARY IMPULSE UPSTREAM HAS YET TO ARRIVE...THE SVR
THREATS WILL LIKELY INCREASE YET THIS EVENING DOWNSTREAM INTO ERN
AR...WRN TN AND FAR NWRN MS.  FUTURE WATCHES MAY BE NEEDED EAST OF
THE CURRENT WW IN A FEW HOURS.

..RACY.. 11/21/2007

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

ATTN...WFO...PAH...MEG...JAN...LSX...LZK...SGF...SHV...

34039389 37549087 37428858 35938877 34389003 33589229

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