MESO: Mesoscale Discussion 2206

ACUS11 KWNS 251300
SWOMCD
SPC MCD 251300
LAZ000-MSZ000-TXZ000-251400-

MESOSCALE DISCUSSION 2206
NWS STORM PREDICTION CENTER NORMAN OK
0700 AM CST TUE DEC 25 2012

AREAS AFFECTED...SRN LA AND PORTIONS OF SERN TX INCLUDING THE UPPER
TX COAST

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

VALID 251300Z - 251400Z

PROBABILITY OF WATCH ISSUANCE...95 PERCENT

SUMMARY...AN INCREASE IN SURFACE-BASED TSTMS IS ANTICIPATED THROUGH
THE REMAINDER OF THE MORNING HOURS IN THE WARM SECTOR SOUTH OF A
WARM FRONT. SUPERCELLS AND BOWING SEGMENTS ARE LIKELY WITH A THREAT
FOR TORNADOES...DAMAGING WINDS AND LARGE HAIL. ONE OR MORE TORNADO
WATCHES WILL LIKELY BE NEEDED BY 16Z.

DISCUSSION...SURFACE LOW PRESSURE WILL CONTINUE TO ORGANIZE OVER S
TX THIS MORNING AS A STRONG SHORTWAVE APPROACHES FROM THE WEST. A
WARM FRONT EXTENDED FROM NR GYB TO BTR AT 12Z AND WILL LIFT SLOWLY
NWD THIS MORNING AS THE SFC LOW MOVES EWD TO N OF HOU BY 16Z.
CONTINUED LOW-LEVEL MOISTURE ADVECTION COUPLED WITH COOLING
MID-LEVEL TEMPERATURES AS THE SHORTWAVE APPROACHES WILL RESULT IN A
MODERATELY UNSTABLE AIR MASS WITH SBCAPE INCREASING TO BETWEEN 1500
AND 2000 J/KG. WIND FIELDS THROUGHOUT THE LOWER/MIDDLE TROPOSPHERE
WILL CONTINUE TO STRENGTHEN AND BECOME INCREASINGLY SUPPORTIVE OF
SUPERCELL TSTM DEVELOPMENT AS DEEP LAYER SHEAR VALUES EXCEED 60 KTS.
INCREASING LOW-LEVEL FLOW WILL RESULT IN 0-1 KM SRH OF 300 M2/S2 OR
GREATER THROUGHOUT THE WARM SECTOR AND NEAR THE WARM
FRONT...FAVORING LOW-LEVEL ROTATION AND TORNADO DEVELOPMENT. WITH
TIME...INITIALLY DISCRETE CELLS MAY MERGE INTO LINE SEGMENTS WITH AN
ENHANCED WIND DAMAGE THREAT DUE TO BOWING STRUCTURES/MESOVORTEX
DEVELOPMENT. LARGE HAIL IS ALSO LIKELY WITH DISCRETE SUPERCELLS. ONE
OR MORE TORNADO WATCHES WILL LIKELY BE REQUIRED PRIOR TO 16Z.

..BUNTING/MEAD.. 12/25/2012

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

ATTN...WFO...LIX...LCH...HGX...

LAT...LON 30929524 30939398 30959320 30909169 30749110 30519014
30308948 29758899 29048905 29119095 29689291 29479430
29079486 29139545 29749587 30679580 30929524

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