ZCZC SPCSWODY1 ALL ACUS01 KWNS 210557 SPC AC 210553 STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWNS. VALID 211200Z - 221200Z THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF SE TX...SRN LA/MS/AL AND THE WRN FL PANHANDLE. THIS AREA LIES TO THE RIGHT OF A LINE FROM 10 NNE GLS 45 NNW BPT 25 ENE POE 30 NNE HEZ 40 S GWO 20 E TUP 25 N GAD 20 SE DHN PFN. SURROUNDING THE ABOVE AREA...THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 25 SSE CRP 35 SW ALI 50 S LRD ...CONT... 10 SE DRT 35 SW JCT 25 N CLL 10 NW GGG 15 N GLH 25 NNW BNA 45 S LOZ 10 S ATL 40 ENE MGR 40 SE TLH. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 60 S MRF 30 SE INK 10 SSE ABI 20 N FTW 40 NE PRX 30 NNW LIT 30 WSW PAH 45 WNW SDF 20 S LUK 45 NE CRW 25 S CHO 50 NNE RWI 35 ESE ECG ...CONT... 10 NNE DAB PIE. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 15 ENE BLI 20 ESE SEA PDX 40 N ONP. ...SYNOPSIS... UPPER LOW NOW OVER NW MEXICO EXPECTED TO DROP ESE TOWARD COT/NIR LATER TODAY BEFORE TURNING NE INTO ERN AR/NW MS BY 12Z SATURDAY. EVOLUTION AT LOWER LEVELS EXPECTED TO BE FAIRLY COMPLICATED THIS PERIOD. LEAD SURFACE WAVE...NOW NEAR CLL/IAH...SHOULD REDEVELOP NEWD ALONG INVERTED TROUGH EXTENDING ACROSS NRN LA/MS INTO MIDDLE TN. FARTHER S...IN RESPONSE TO INCREASING DYNAMIC SUPPORT AHEAD OF EJECTING UPPER VORT...EXPECT AN ADDITIONAL SURFACE WAVE TO DEVELOP LATER TODAY OVER THE SRN PART OF THE TX GULF COASTAL PLAIN... DESPITE SHALLOW LAYER OF COOL AIR ACROSS REGION. THIS WAVE SHOULD MOVE NEWD AHEAD OF VORT...REACHING NE LA BY 12 SATURDAY. ...S CNTRL INTO SE TX EARLY TODAY THRU EARLY AFTN... THUNDERSTORMS NOW OVER THE BIG BEND REGION...MARKING LEADING EDGE OF APPROACHING UPPER VORT...EXPECTED TO INTENSIFY AND SPREAD E ACROSS S CNTRL TX BY DAWN TODAY. GIVEN SUSTAINED NATURE OF LARGE SCALE ASCENT...INCREASING ELEVATED MOISTURE INFLOW AND STRENGTHENING DEEP SHEAR...POTENTIAL WILL EXIST FOR SUPERCELLS WITH LARGE HAIL AND POSSIBLY DAMAGING WINDS. THIS ACTIVITY SHOULD CONTINUE E/ENE ALONG THE CNTRL AND NRN TX GULF COAST THROUGH THE DAY...WITH A CONTINUED THREAT FOR HAIL AND DAMAGING WIND DESPITE DIMINISHING MID LEVEL LAPSE RATES WITH EWD EXTENT. ADDITIONAL STORMS...POSSIBLY SURFACE-BASED...MAY ALSO DEVELOP ALONG THE TX GULF COASTAL AND/OR OVER THE GULF COASTAL WATERS AHEAD OF THE MAIN VORT-INDUCED CONVECTION. THIS LATTER ACTIVITY WILL HAVE ACCESS TO INCREASING LOW LEVEL SHEAR AND MAY PRODUCE ISOLATED TORNADOES IN SE TX/SRN LA. ...LA/MS/AL INTO TN VLY/WRN GA... A MORE SIGNIFICANT THREAT FOR TORNADOES...INCLUDING A COUPLE STRONG ONES...EXPECTED TO DEVELOP OVER SRN LA/MS LATER THIS AFTERNOON INTO TONIGHT AS SE TX/NW GULF STORMS SPREAD EWD AND COME UNDER INFLUENCE OF INCREASING SHEAR/LARGE SCALE ASCENT ASSOCIATED WITH EJECTING VORT. WHILE STRONG HEIGHT FALLS AND BACKING OF SHEAR VECTORS OVER TIME SUGGEST EVENTUAL EVOLUTION INTO A SQUALL LINE...STRENGTH OF DEEP SHEAR /ON THE ORDER OF 70 KTS/ AND QUALITY OF MOISTURE INFLOW /SURFACE DEWPOINTS IN THE MID TO UPPER 60S/...SUGGEST GOOD CHANCE FOR A FEW DISCRETE SUPERCELLS WITH TORNADOES. THE GREATEST THREAT SHOULD DEVELOP LATE TOMORROW EVENING THROUGH EARLY SATURDAY OVER SRN LA/MS AND AL...ESPECIALLY IF INCREASING UPPER DIVERGENCE RESULTS IN DEVELOPMENT OF SUB-SYNOPTIC LOWS/WAVES ALONG SW/NE CONFLUENCE BANDS OVER REGION. ...SE TX INTO LA/MS/AL EARLY TODAY THRU MID AFTN... ELEVATED WARM ADVECTION THUNDERSTORMS NOW OVER SE TX/LA EXPECTED TO SPREAD EWD ALONG THE CNTRL/ERN GULF CST TODAY...AS SURFACE FRONT GRADUALLY LIFTS NWD ACROSS REGION. A FEW STORMS ON THE SRN/WRN FRINGE OF THIS ACTIVITY MAY BECOME SURFACE-BASED LATER TODAY... ESPECIALLY FROM SRN MS/AL INTO THE FL PANHANDLE. INCREASINGLY RICH BOUNDARY LAYER MOISTURE INFLOW AND SLIGHTLY BACKED FLOW INVOF WARM FRONT SUGGEST A LIMITED THREAT FOR TORNADOES WITH THESE STORMS. ..CORFIDI.. 02/21/03 NNNN |