DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 050533
SWODY1
SPC AC 050532

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1132 PM CST SUN NOV 04 2012

VALID 051200Z - 061200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF SERN TX AND SRN
LA...

...SYNOPSIS...
A POTENT...COMPACT PV MAX IN THE MIDDLE/UPPER LEVELS WILL MOVE SSEWD
FROM THE CNTRL/SRN PLAINS TO THE LOWER MS VALLEY TODAY. THE
INFLUENCE OF A SUBTROPICAL JET MAX LYING OVER THE NRN GULF OF MEXICO
AND ADJACENT GULF COAST STATES WILL STEER THE PV MAX MORE TO THE E
ACROSS MS/AL TONIGHT. AT THE SFC...A DIFFUSE FRONT WILL REMAIN
QUASI-STATIONARY FROM SRN PARTS OF THE CNTRL GULF COAST STATES INTO
CNTRL/SRN TX. AS THE PV MAX INTERACTS WITH THE DIFFUSE FRONT...A
FRONTAL WAVE WILL DEVELOP OVER SRN LA AND SHIFT EWD ACROSS THE NRN
GULF. THE FRONTAL SEGMENT TRAILING W OF THE WAVE WILL BECOME
REINFORCED BY A COOL/CONTINENTAL AIR MASS SURGING SWD OVER THE
CNTRL/SRN PLAINS.

...CNTRL/SRN TX EWD INTO SRN SECTIONS OF THE CNTRL GULF COAST STATES
THIS AFTERNOON INTO TONIGHT...
AS 500-MB HEIGHT FALLS OF 60-90 GEOPOTENTIAL METERS PER 12 HOURS
RELATED TO THE PV MAX OVERSPREAD THE LOWER MS VALLEY...STRONG
DCVA/ASCENT WILL BEGIN TO OVERLAY THE WARM SECTOR S OF THE DIFFUSE
FRONT THIS AFTERNOON. THIS WILL SUPPORT AN INCREASE IN THE COVERAGE
AND INTENSITY OF SFC-BASED THUNDERSTORMS FROM SRN LA INTO PARTS OF
CNTRL/SRN TX THIS AFTERNOON...WITH THE ACTIVITY SHIFTING SEWD/ESEWD
THROUGH TONIGHT.

THE COMPACT NATURE OF THE PV MAX WILL LIMIT PROSPECTS FOR A MORE
EXPANSIVE WARM SECTOR TO EVOLVE. HOWEVER...THE MASS RESPONSE IN
ASSOCIATION WITH THE FRONTAL WAVE WILL ALLOW A ZONE OF WARM/MARITIME
AIR TO BE MAINTAINED INLAND. FORECAST SOUNDINGS SUGGEST THAT DIURNAL
HEATING AMIDST LOWER/MIDDLE 60S DEWPOINTS THAT CHARACTERIZE THE WARM
SECTOR WILL SUPPORT 1000-2000 J/KG OF MLCAPE FROM PARTS OF CNTRL/SRN
TX INTO SWRN LA WITH MORE MARGINAL INSTABILITY FARTHER E INTO SERN
LA. HOWEVER...STRONGER FORCING FOR ASCENT ACROSS S-CNTRL AND SERN LA
WILL LIKELY OFFSET MORE MARGINAL THERMODYNAMIC PROFILES THERE.

WITH 0-6-KM BULK SHEAR MAGNITUDES OF 35-50 KT AND AT LEAST SOME
COMPONENT OF DEEP SHEAR VECTORS ORIENTED ORTHOGONAL TO THE
INITIATING BOUNDARY/FRONT...A MIX OF SUPERCELL STRUCTURES AND
QUASI-LINEAR CONVECTIVE SEGMENTS CAPABLE OF SVR WINDS/HAIL IS
ANTICIPATED. THE GREATEST CONCERN FOR THIS ACTIVITY WILL BE ACROSS
THE SLIGHT-RISK AREA THAT COVERS PARTS OF SERN TX AND SRN LA. WEAKER
LOW-LEVEL CONVERGENCE/ASCENT YIELDING LESSER CONVECTIVE COVERAGE AND
WEAKER DEEP SHEAR WILL MINIMIZE THE SVR THREAT W OF THE SLIGHT-RISK
AREA...WHILE MORE LIMITED BUOYANCY WILL LIMIT THE SVR THREAT E OF
THE SLIGHT-RISK AREA.

..COHEN/PETERS.. 11/05/2012

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