DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 010650
SWODY2
SPC AC 010649

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1249 AM CST SAT MAR 01 2014

VALID 021200Z - 031200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF EASTERN
TEXAS...LOUISIANA...SOUTHERN ARKANSAS...WESTERN AND SOUTHERN
MISSISSIPPI...

...SYNOPSIS...
A DEEP CYCLONE CURRENTLY CENTERED OFF THE CNTRL CA COAST WILL HAVE
DEVOLVED INTO A SHORTWAVE TROUGH...WHICH WILL ADVANCE FROM THE SRN
ROCKIES TO THE MIDDLE MS VALLEY ON D2/SUN. WHILE THIS FEATURE WILL
DE-AMPLIFY IN CONFLUENT FLOW ALOFT...DISTURBANCE-PRECEDING ASCENT
WILL SUPPORT THE ENEWD PROGRESSION OF A WAVE ALONG THE LEADING EDGE
OF SHALLOW ARCTIC AIR FROM N-CNTRL TX TO THE ARKLATEX TO THE
CNTRL/SRN APPALACHIANS. A SFC DRYLINE WILL EXTEND S OF THE FRONTAL
WAVE OVER CNTRL/SRN TX AND WILL BE OVERTAKEN BY THE ARCTIC AIR
ADVANCING SWD BEHIND THE WAVE. E OF THE DRYLINE...A STRENGTHENING
LLJ WILL ENCOURAGE THE POLEWARD TRANSPORT OF LOW-LEVEL MOISTURE INTO
ERN PORTIONS OF THE SRN PLAINS TO THE LOWER MS VALLEY. SFC ANALYSIS
REVEALS THE INITIAL STAGES OF THIS PROCESS...WITH DEWPOINTS IN THE
LOWER/MIDDLE 60S PRESENTLY REACHING THE LOWER TX COAST.

...ERN PORTIONS OF THE SOUTHERN PLAINS EWD TO THE LOWER MISSISSIPPI
VALLEY...
ISOLATED ELEVATED THUNDERSTORMS -- PERHAPS WITH SVR HAIL -- ROOTED
ATOP THE SHALLOW ARCTIC AIR MAY BE ONGOING SUN MORNING ACROSS PARTS
OF FAR SRN OK AND NRN TX. SIMILAR ACTIVITY MAY PERSIST AS FAR AS
100-150 MILES /OR MORE/ BEHIND THE SWD/SEWD-MOVING SFC BOUNDARY
THROUGH THE PERIOD. THIS WILL OCCUR AS ISENTROPIC ASCENT AND
ELEVATED MOISTURE TRANSPORT ACCOMPANYING THE LLJ PERSIST BENEATH
H7-H5 LAPSE RATES AROUND 7-7.5 C/KM AND 50-70-KT H5 WSWLY/S.

MEANWHILE...DIURNAL HEATING OF MIDDLE-60S SFC DEWPOINTS BENEATH AN
EML PLUME ORIGINATING FROM THE NRN MEXICAN PLATEAU WILL YIELD
MODERATE TO LOCALLY STRONG INSTABILITY E OF THE DRYLINE DURING THE
AFTERNOON. WHILE THERE IS SOME UNCERTAINTY REGARDING THE COVERAGE OF
SFC-BASED CONVECTION...MID-LEVEL HEIGHT FALLS PRECEDING THE
SHORTWAVE TROUGH WILL OVERSPREAD THIS INSTABILITY THROUGH THE DAY.
THIS WILL BE ASSOCIATED WITH AN INCREASE IN THE CHANCE FOR
CONVECTIVE INITIATION IN CLOSER PROXIMITY TO THE SFC FRONT AND ON
THE PERIPHERY OF STRONGER CAPPING ACCOMPANYING THE EML PLUME -- I.E.
FROM THE ARKLATEX TO NERN/E-CNTRL TX. THIS ACTIVITY WOULD SPREAD
EWD/SEWD TO PARTS OF THE LOWER MS VALLEY THROUGH SUN NIGHT AS THE
ARCTIC BOUNDARY SHIFTS SEWD...AND WILL YIELD A HIGHER SVR POTENTIAL
FROM ERN TX TO LA AND ACROSS FAR SRN AR.

STRONG DEEP SHEAR OWING TO STRENGTHENING MID-LEVEL FLOW WOULD
ENCOURAGE THE ORGANIZATION OF SFC-BASED CONVECTION...WITH INITIALLY
MIXED SUPERCELL/QLCS MODES OVER ERN TX TRANSITIONING TO MORE LINEAR
MODES FARTHER E. DAMAGING WIND GUSTS AND SVR HAIL WILL BE THE
PRIMARY CONCERNS WITH THIS ACTIVITY...WITH THE DMGG-WIND POTENTIAL
PERHAPS BECOMING OF GREATER CONCERN AS STORMS SPREAD ACROSS PARTS OF
LA. STRONG LOW-LEVEL SHEAR BENEATH 40-55 KT OF SWLY H85-H7 FLOW WILL
EXIST AND ALSO YIELD SOME POTENTIAL FOR TORNADOES. THERE MAY BE A
TENDENCY FOR THE ARCTIC BOUNDARY TO UNDERCUT INITIALLY SFC-BASED
CONVECTION. HOWEVER...FAST MID-LEVEL FLOW CONSISTING OF AT LEAST
SOME BOUNDARY-ORTHOGONAL COMPONENT S OF THE FRONTAL WAVE MAY
MAINTAIN NEAR-SFC-BASED CONVECTION. ANY FRONT-UNDERCUT CONVECTION
WOULD STILL SUPPORT A HAIL RISK.

AS THE FRONTAL WAVE DEVELOPS ENEWD AND AWAY FROM RICHER LOW-LEVEL
MOISTURE/BUOYANCY WHILE WEAKENING SUN NIGHT...AND THE ARCTIC
BOUNDARY PINCHES OFF THE NRN EXTENT OF RETURNING MOISTURE...THE SVR
POTENTIAL WILL LESSEN ACROSS ERN PARTS OF THE LOWER MS VALLEY.
HOWEVER...SOME SVR POTENTIAL WILL EXIST AS FAR E AS SRN MS AND SERN
LA LATE SUN NIGHT AS THE LEADING EDGE OF CONVECTIVELY ENHANCED COLD
POOLS INTERCEPT RICHER LOW-LEVEL MOISTURE.

..COHEN.. 03/01/2014

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