DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 280822
SWODY3
SPC AC 280821

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0221 AM CST FRI FEB 28 2014

VALID 021200Z - 031200Z

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

...SYNOPSIS...
A MID-LEVEL SHORTWAVE TROUGH IN THE SRN STREAM WILL ADVANCE FROM THE
SRN ROCKIES TO THE MIDDLE MS VALLEY WHILE DE-AMPLIFYING IN CONFLUENT
FLOW ALOFT. ASCENT PRECEDING THIS DISTURBANCE WILL ENCOURAGE THE
ENEWD PROGRESSION OF A FRONTAL WAVE FROM N-CNTRL TX TO THE ARKLATEX
TO THE TN VALLEY ALONG THE LEADING EDGE OF SHALLOW ARCTIC AIR. A SFC
TROUGH/DRYLINE WILL EXTEND S OF THE FRONTAL WAVE OVER CNTRL/SRN TX
AND WILL BE OVERTAKEN BY THE ARCTIC AIR ADVANCING SWD ON THE
BACKSIDE OF THE WAVE. E OF THE DRYLINE...A LLJ WILL ENCOURAGE THE
NWD TRANSPORT OF RICHER GULF MOISTURE INTO ERN PORTIONS OF THE SRN
PLAINS TO THE LOWER MS VALLEY -- ORIGINATING FROM A RESERVOIR OF
1.5-1.8-INCH PW CURRENTLY OVER THE BAY OF CAMPECHE PER GPS DATA.

...ERN PORTIONS OF THE SOUTHERN PLAINS EWD TO THE LOWER MISSISSIPPI
VALLEY...
ISOLATED STORMS...PERHAPS WITH MARGINALLY SVR HAIL...MAY BE ONGOING
AT THE BEGINNING OF THE PERIOD ACROSS PARTS OF FAR SRN OK AND NRN TX
AS WARM ADVECTION CONTINUES ATOP THE SHALLOW COLD DOME.
MEANWHILE...THE INFLUX OF MIDDLE/UPPER 60S SFC DEWPOINTS E OF THE
DRYLINE BENEATH AN EML PLUME EMANATING FROM THE NRN MEXICAN PLATEAU
IS EXPECTED TO RESULT IN MODERATE INSTABILITY FROM THE ARKLATEX INTO
E-CNTRL TX BY MID-DAY. AS MID-LEVEL HEIGHT FALLS PRECEDING THE
SHORTWAVE TROUGH OVERSPREAD DIURNALLY ENHANCED BUOYANCY...SFC-BASED
CONVECTION WILL LIKELY FORM ALONG THE FRONT AND ON THE PERIPHERY OF
STRONGER CAPPING ACCOMPANYING THE EML PLUME -- I.E. FROM THE
ARKLATEX TO NERN/E-CNTRL TX -- BY MID-AFTERNOON. THIS ACTIVITY WILL
SPREAD EWD/SEWD TO PARTS OF THE LOWER MS VALLEY THROUGH SUN
NIGHT...WHILE THE SEWD ADVANCE OF THE ARCTIC BOUNDARY PINCHES OFF
MOIST SLY LOW-LEVEL TRAJECTORIES ON THE WARM SIDE OF THE FRONTAL
WAVE AND EXTENDS THE SVR POTENTIAL TO THE COAST.

STRONG DEEP SHEAR OWING TO 50-70 KT OF H5 WSWLY/S WILL ASSIST STORM
ORGANIZATION...WITH INITIALLY MIXED SUPERCELL/QLCS MODES OVER ERN TX
TRANSITIONING TO MORE LINEAR MODES FARTHER E. DAMAGING WIND
GUSTS...AND SVR HAIL JUST AFTER SFC-BASED CONVECTIVE
INITIATION...WILL BE THE PRIMARY CONCERNS WITH THIS ACTIVITY. THE
GREATEST POTENTIAL FOR SVR STORMS WILL EXTEND FROM ERN TX TO
NRN/CNTRL LA...WHERE STRONG LOW-LEVEL SHEAR BENEATH 40-55 KT OF SWLY
H85-H7 FLOW WILL EXIST AND ALSO YIELD SOME POTENTIAL FOR TORNADOES.
AS THE FRONTAL WAVE DEVELOPS ENEWD AND AWAY FROM RICHER LOW-LEVEL
MOISTURE/BUOYANCY WHILE WEAKENING SUN NIGHT...THE SVR POTENTIAL WILL
BECOME INCREASINGLY MARGINAL ACROSS ERN PARTS OF THE MS VALLEY.

..COHEN.. 02/28/2014

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