ZCZC SPCSWODY1 ALL ACUS01 KWNS 271633 SPC AC 271630 STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWNS. VALID 271630Z - 281200Z THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 25 SSE CTY 10 N GNV 40 SE JAX. THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 35 E OKC 40 ENE BVO SZL IRK BRL 40 W MMO 45 S CGX LAF HUF PAH 15 NNE LIT 35 NNW TXK PRX 10 ENE ADM 35 E OKC. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 20 E PNS 15 SSW ATL SOP HSE. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 45 NNW YNG 25 SW CAK 15 NNE BMG 10 ESE PAH 40 N DYR 10 SE JBR 20 ENE LIT 25 SSW HOT 30 SE DAL 15 ESE CNM 30 ESE LVS 30 WSW CEZ 50 ESE U24 50 ENE ENV 10 NNW BKE 35 SSW GEG 35 SSW FCA 35 NW CTB. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 30 N HVR 60 ENE LWT 50 ESE BIL 35 WSW RWL 20 NNE EHA 45 NE AMA 40 NW CSM 25 E PNC 10 NNE TOP 50 WSW DSM 35 SSE EAU 20 NNW MQT. ...SYNOPSIS... STRONG TROUGH CURRENTLY CROSSING CENTRAL ROCKIES WILL SHIFT EWD INTO PLAINS BY TONIGHT. ASSOCIATED SURFACE LOW MOVING NEWD FROM SERN NEB TO SRN WI WITH TRAILING COLD FRONT SURGING SEWD ACROSS PLAINS REACHING MID MS VALLEY TO SCENTRAL TX BY END OF PERIOD. 50- 60 KT LLJ PRECEDES FRONT WITH ONLY A MARGINALLY MOIST AIRMASS RETURNING FROM NWRN GULF. SURFACE AND UPPER SYSTEM OVER ERN GULF OF MEXICO WILL SHEAR EWD ACROSS FL TODAY. SLY FLOW ACROSS FL HAS RESULTED IN DESTABILIZING AIRMASS SPREADING ACROSS PENINSULA OVERNIGHT. ...FL... REF WW 78 AND MCD 340. WITH THE WEAK CAP AND RELATIVELY STEEP LAPSE RATES ALONG WITH MLCAPES AROUND 1500 J/KG...CONDITIONS ARE FAVORABLE FOR SEVERE THUNDERSTORMS MUCH OF FL PEN TODAY. DEEP LAYER SHEAR TO 40KT WILL SUPPORT ORGANIZED THUNDERSTORMS. WHILE VEERING PROFILES VICINITY BOUNDARIES...PARTICULARLY ERN PEN...FAVOR ISOLATED SUPERCELLS THIS AFTERNOON. PRIMARY THREAT WILL BE LARGE HAIL BUT ISOLATED TORNADOES/WIND DAMAGE POSSIBLE ASSOCIATED WITH ANY SUPERCELL THAT CAN DEVELOP. ...CENTRAL U.S... 12Z SOUNDINGS IN RETURN FLOW OFF NWRN GULF OF MEXICO CONFIRM THAT MOISTURE IS VERY MARGINAL FOR SUPPORT OF STRONG CONVECTION VICINITY OF THE COLD FRONT LATER THIS AFTERNOON/TONIGHT. HOWEVER THE STRONG ASCENT AND MID LEVEL COOLING ASSOCIATED WITH THE VIGOROUS POLAR JET MAX ROTATING INTO CENTRAL/SRN PLAINS DURING AFTERNOON EXPECTED TO BE SUFFICIENT FOR THUNDERSTORM INITIATION ALONG/AHEAD OF COLD FRONT. DEWPOINTS RISING INTO LOW/MID 50S COUPLED WITH SURFACE TEMPERATURES TO NEAR 80F WILL BE SUFFICIENT TO DEVELOP MLCAPES FROM 500-1000 J/KG ACROSS ERN OK INTO WRN MO BY LATE AFTERNOON. MODELS SUPPORT THUNDERSTORM DEVELOPMENT PRIOR TO 00Z VICINITY WRN MO AND THEN INTO NERN OK AFTER 00Z. GIVEN THE LIMITED INSTABILITY PRIMARY THREAT WILL BE MARGINALLY SEVERE HAIL AND WIND DAMAGE IN FAST MOVING STORMS. THE SEVERE THREAT WILL LIKELY CONTINUE NE/EWD ACROSS MID MS VALLEY INCREASE AND VERY STRONG SHEAR PERSISTS VICINITY OF THE CONVECTION. ..HALES/BANACOS.. 03/27/03 NNNN |