MESO: Mesoscale Discussion 0157

ACUS11 KWNS 121957
SWOMCD
SPC MCD 121957
ALZ000-FLZ000-MSZ000-LAZ000-TXZ000-122100-

MESOSCALE DISCUSSION 0157
NWS STORM PREDICTION CENTER NORMAN OK
0157 PM CST TUE FEB 12 2013

AREAS AFFECTED...SRN LA...SRN MS...SRN AL...WRN FL PANHANDLE

CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY

VALID 121957Z - 122100Z

PROBABILITY OF WATCH ISSUANCE...95 PERCENT

SUMMARY...A THREAT FOR TORNADOES...DMGG WINDS...AND HAIL...IS
EXPECTED TO INCREASE THIS AFTERNOON ACROSS THE CNTRL GULF COAST IN
ASSOCIATION WITH A WEAK SFC CYCLONE AND ATTENDANT WARM FRONT. A
TORNADO WATCH WILL LIKELY BE NEEDED.

DISCUSSION...VISIBLE SATELLITE AND LIGHTNING DATA SHOW CONVECTION
INCREASING INVOF A WEAK SFC LOW...WHICH WAS CENTERED JUST N OF BPT
AS OF 19Z. AN ATTENDANT WARM FRONT PARALLEL TO THE GULF COAST IS
SLOWLY LIFTING NWD ACROSS COASTAL SRN LA...WITH DEWPOINTS OF 65-70 F
SPREADING INLAND. THE 12Z LCH SOUNDING MODIFIED FOR REPRESENTATIVE
19Z SFC CONDITIONS SUGGESTS THAT DEVELOPING CONVECTION ALONG/S OF
THE WARM FRONT WILL LIKELY BE SFC-BASED...WITH SBCAPE VALUES
APPROACHING 1000 J/KG. MODEST HEIGHT FALLS OVERSPREADING THE AREA IN
RESPONSE TO AN UPPER TROUGH CENTERED OVER W TX...COMBINED WITH
FURTHER BOUNDARY LAYER HEATING AND CONVERGENCE ALONG A COLD FRONT
ATTENDANT TO THE SFC LOW...MAY SUPPORT DEVELOPMENT OF TSTMS THIS
AFTERNOON THROUGH SRN LA.

ADDITIONAL SFC-BASED TSTMS MAY DEVELOP INVOF THE WARM FRONT INTO SRN
MS/AL AND EVENTUALLY THE WRN FL PANHANDLE WITHIN A WEAK WAA
REGIME...WHERE FAVORABLE HODOGRAPHS/LOW-LEVEL SHEAR PROFILES /PER
LCH/MOB VWP DATA/ ARE IN PLACE. DEEP-LAYER SHEAR PROFILES ARE
FAVORABLE FOR ISOLATED SUPERCELLS AND SMALL BOWING SEGMENTS...WITH
AN ENHANCED TORNADO THREAT ACCOMPANYING DISCRETE STORMS FORMING NEAR
THE WARM FRONT/SFC LOW. AN ADDITIONAL THREAT OF DMGG WINDS/HAIL MAY
ALSO ACCOMPANY THE STRONGER STORMS.

..ROGERS/MEAD.. 02/12/2013

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

ATTN...WFO...TAE...BMX...MOB...JAN...LIX...LCH...

LAT...LON 29089053 29229138 29589312 29709354 30099377 30409370
30579329 30709193 30899075 31208997 31398928 32028844
32128678 31898619 31598608 30918584 30518616 30288727
30278884 29858947 29279018 29089053

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