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Mar 1, 2014 0700 UTC Day 2 Convective Outlook

March 1, 2014

Mar  1, 2014 0700 UTC Day 2 Convective Outlook

day2otlk

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.

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