ZCZC SPCSWODY1 ALL ACUS01 KWNS 051251 SPC AC 051250 STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWNS. VALID 051300Z - 061200Z THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 20 SSW BPT 20 WSW POE 35 NNE ESF 50 SSE GLH 45 W CBM 30 SE HSV 55 WSW AVL CLT 40 WSW SOP FLO 30 WNW CHS 50 NNE AYS 30 S TLH. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 25 SW PSX 50 SSW CLL 50 NE LFK 25 NNE GLH 45 NNE UOX 25 E CKV 55 SW LEX 10 N 5I3 15 NW LYH 35 NE ORF ...CONT... 40 SSE JAX 40 S CTY. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 20 WSW YUM 25 E BLH 50 W PRC 20 W FLG 35 NNE INW 20 SW GUP 40 SSW GNT 45 NNW TCS 35 S TCS 30 WSW ELP. ...SYNOPSIS... FULL LATITUDE POSITIVE TILT TROUGH FROM THE GREAT LAKES INTO THE DESERT SW WILL PROGRESS EWD THROUGH THE PERIOD AS A BELT OF STRONG MID/UPPER-LEVEL WINDS PERSISTS FROM TX INTO THE MIDDLE ATLANTIC STATES. MEANWHILE...STRONG SURFACE COLD FRONT EXTENDING FROM NEW ENGLAND SWWD INTO CNTRL TX WILL SWEEP ACROSS MUCH OF THE GULF COAST REGION AND SHOULD BE LOCATED FROM CNTRL VA INTO THE FL PNHDL BY 12Z THURSDAY. WARM/MARINE FRONT SITUATED FROM THE NRN GULF OF MEXICO TO ALONG THE GA/SC COASTS WILL LIFT NWD INTO THE INTERIOR GULF COAST PRIOR TO THE PASSAGE OF THE COLD FRONT TONIGHT. ...LOWER MS VALLEY INTO THE SERN STATES... SURFACE DEWPOINTS IN THE MID TO UPPER 60S ACROSS THE NRN GULF OF MEXICO WILL MOVE INLAND TODAY IN RESPONSE TO CYCLOGENESIS OVER NRN LA/SRN AR ALONG THE ADVANCING COLD FRONT. DEEPER MOISTURE RETURN WILL INITIALLY CONFINED TO SERN TX INTO LA/SRN MS BENEATH 40-45 KT LOW-LEVEL JET AXIS...BEFORE SPREADING RAPIDLY NEWD ACROSS THE REMAINDER OF THE GULF COAST REGION AND INTO GA/SC TONIGHT AS LOW- LEVEL JET SHIFTS EWD AND STRENGTHENS TO 60-70 KTS. INITIAL TSTM DEVELOPMENT WILL LIKELY OCCUR OVER SERN TX/SWRN LA THIS AFTERNOON AS COLD FRONT INTERACTS WITH MARGINALLY UNSTABLE AIRMASS TO THE S OF RETREATING WARM FRONT. STRONG/SEVERE TSTMS SHOULD INCREASE IN COVERAGE DURING THE EVENING AS THE COLD FRONT ACCELERATES EWD ACROSS LOWER MS VALLEY IN RESPONSE TO THE APPROACHING MID/UPPER-LEVEL TROUGH. ACTIVITY SHOULD THEN CONTINUE OVERNIGHT ALONG AND AHEAD OF COLD FRONT INTO GA AND SC. FORECAST HODOGRAPHS FROM SRN MS THROUGH CNTRL/SRN PARTS OF AL/GA INTO SC ARE QUITE FAVORABLE FOR SEVERE TSTMS OVERNIGHT WITH 0-6 KM SHEAR VALUES OF 30-40 M/S AND 0-3 KM SRH VALUES OF 300-400 M2/S2. PRIMARY QUESTION IS THE AMOUNT OF DESTABILIZATION THAT WILL OCCUR IN THE WARM SECTOR AHEAD OF COLD FRONT. ALTHOUGH MID-LEVEL LAPSE RATES WILL NOT BE PARTICULARLY STEEP...SURFACE DEWPOINTS SHOULD INCREASE TO THE MID 60S AS FAR N AS CNTRL AL/GA...CONTRIBUTING TO SBCAPES OF 500-1000 J/KG. THE STRONG WIND FIELDS AND MARGINAL INSTABILITY WILL SUPPORT A WIND DAMAGE THREAT FROM THE LOWER MS VALLEY INTO GA AND SC...PRIMARILY IN ASSOCIATION WITH ISOLATED BOWS/SUPERCELLS EMBEDDED IN SHORT CONVECTIVE LINE SEGMENTS ALONG THE COLD FRONT. ISOLATED TORNADOES ARE ALSO POSSIBLE GIVEN THE FORECAST STRENGTH OF THE LOW-LEVEL SHEAR AND HODOGRAPH CURVATURE. ..MEAD.. 03/05/03 NNNN |