MESO: Mesoscale Discussion 2149

ACUS11 KWNS 211718
SWOMCD
SPC MCD 211717
TNZ000-MSZ000-MOZ000-ARZ000-LAZ000-TXZ000-OKZ000-211915-

MESOSCALE DISCUSSION 2149
NWS STORM PREDICTION CENTER NORMAN OK
1117 AM CST WED NOV 21 2007

AREAS AFFECTED...MOST OF AR...EXTREME SERN MO...FAR WRN TN...NWRN
MS...EXTREME NERN TX AND NRN LA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 211717Z - 211915Z

PROBABILITIES FOR SEVERE WEATHER /LARGE HAIL...DMGG WIND GUSTS AND A
TORNADO OR TWO/ WILL INCREASE THROUGH MID-AFTN ACROSS PARTS OF THE
DISCUSSION AREA. A WW WILL LIKELY BE REQUIRED FOR PARTS OF THE
REGION.

VICI OK PROFILER RECENTLY SAMPLED A MID-LVL SPEED MAX OF AROUND 65
KTS ROUNDING THE BASE OF THE UPR LVL TROUGH OVER THE CNTRL PLAINS.
THIS JET MAX WILL APPROACH THE MID-SOUTH BY MID-AFTN WITH FORCING
FOR LARGE SCALE ASCENT INCREASING IN WAKE OF THE SUBTROPICAL IMPULSE
DEPARTING TO THE E. LOW-LEVEL MOISTURE PROFILES CONTINUE TO
INCREASE WITH SFC DEW POINTS IN EXCESS OF THE MID-60S AS FAR N AS
THE MO/AR BORDER. HEATING...HOWEVER...HAS BEEN SOMEWHAT LIMITED
OWING TO CONSIDERABLE CLOUDS THROUGHOUT THE WARM SECTOR.
NONETHELESS...BRIEF BREAKS IN THE OVERCAST WILL CONTRIBUTE TO MODEST
DESTABILIZATION WITH MLCAPES APPROACHING 1200-1500 J/KG BY 21Z.

AS THE UPR SYSTEM APPROACHES...WARM SECTOR SFC-BASED TSTMS WILL
LIKELY INCREASE OVER CNTRL/ERN AR AND EXPAND BOTH NEWD AND SWWD INTO
ADJACENT PARTS OF SERN MO AND NERN TX/NWRN LA. THOUGH STRONGEST
BULK SHEAR WILL EXIST FROM AR NWD...AT LEAST 35-40 KT H5 FLOW
EXPECTED INTO NERN TX/LA LATER THIS AFTN WILL SUPPORT SUPERCELLS. A
FEW DISCRETE MODES WILL BE PSBL FOR A FEW HOURS...BUT NUMBER OF
STORMS INITIATING AND INCREASING LINEAR FORCING ASSOCD WITH THE
TROUGH WILL PROBABLY RESULT IN AN EVOLUTION INTO LINE
SEGMENTS/CLUSTERS. LARGE HAIL AND DMGG WINDS WILL BE THE PRIMARY
SVR THREATS. BUT...PROFILERS/VWPS SUGGEST THAT IF A STORM CAN
REMAIN DISCRETE AND DEVIATE TO THE RIGHT...0-1KM SRH WILL SUPPORT A
COUPLE OF TORNADOES. THIS WILL ESPECIALLY BE THE CASE WITH STORMS
THAT DEVELOP WITHIN THE MORE ROBUST THETA-E AXIS OVER SWRN/SCNTRL AR
NEWD TOWARD THE KMEM VCNTY.

OTHER STORMS WILL FORM ALONG THE PRIMARY COLD FRONT IN WAKE OF THE
AFOREMENTIONED ACTIVITY FROM SCNTRL MO SWWD INTO NERN TX. THESE
STORMS WILL MAINLY BECOME A LARGE HAIL/DMGG WIND THREAT.

.RACY.. 11/21/2007

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

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

33339093 32669173 32459322 32329383 32509464 33529521
34189478 34569439 36099293 36769123 36739033 36168951
35418948 34678961 33999002

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