MESO: Mesoscale Discussion 2211

ACUS11 KWNS 281711
SWOMCD
SPC MCD 281710
MSZ000-LAZ000-TXZ000-281915-

MESOSCALE DISCUSSION 2211
NWS STORM PREDICTION CENTER NORMAN OK
1210 PM CDT WED SEP 28 2011

AREAS AFFECTED...SERN TX/SRN LA/SRN MS

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 281710Z - 281915Z

SEVERE THREAT IS EXPECTED TO SLOWLY INCREASE THIS AFTERNOON AS
STORMS DEVELOP/INTENSIFY WITH TIME. EVENTUAL WW ISSUANCE IS
POSSIBLE.

LATEST VISIBLE SATELLITE AND RADAR LOOPS SHOW CONVECTION SLOWLY
DEVELOPING ACROSS THE DISCUSSION AREA...BOTH INVOF A SEA BREEZE
BOUNDARY NEAR THE SERN TX/SRN LA COAST AND ALSO FARTHER N INTO SRN
MS NEAR THE SYNOPTIC-SCALE FRONT. THE CONVECTION IS INITIATING
WITHIN A THERMODYNAMIC ENVIRONMENT FEATURING VERY STEEP LAPSE RATES
THROUGH A DEEP LAYER...AND A VERY MOIST BOUNDARY LAYER. THIS
COMBINED WITH DIURNAL HEATING IS YIELDING MIXED-LAYER CAPE VALUES
NOW AS HIGH AS 3500 J/KG FROM SERN TX EWD ACROSS SRN LA.

AS HEATING/DESTABILIZATION CONTINUES...AND AS A COMPACT UPPER
LOW/VORT MAX SHIFTS SEWD OUT OF OK INTO THE ARKLATEX
REGION...LARGE-SCALE ASCENT SHOULD INCREASE ACROSS THE DISCUSSION
AREA...SUPPORTING AN INCREASE IN BOTH STORM COVERAGE AND INTENSITY.
WHILE PROFILER/VWP DATA AND MORNING RAOBS REVEAL MODEST FLOW ALOFT
-- AND THUS SHEAR VALUES GENERALLY UNSUPPORTIVE OF
SUPERCELLS...DEGREE OF INSTABILITY APPEARS SUFFICIENT TO OVERCOME
THIS LIMITATION AND YIELD AN INCREASING POTENTIAL FOR LARGE HAIL AND
LOCALLY DAMAGING WINDS THROUGH THE AFTERNOON. WHILE WW IS NOT
IMMINENT...INCREASING POTENTIAL MAY EVENTUALLY WARRANT WATCH
ISSUANCE.

..GOSS.. 09/28/2011

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

ATTN...WFO...MOB...JAN...LIX...LCH...SHV...HGX...

LAT...LON 29149485 29219573 29819596 30829504 31449374 31599184
31749049 31288888 30638849 29618947 29399067 29639252
29749414 29149485

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