STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWNS. VALID 031630Z - 041200Z THERE IS A MDT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 40 SSW HEZ 40 SSW SHV 25 SSE DAL 35 NNE MWL 25 E SPS 40 ESE FSI 20 S MLC 40 SW HOT 30 ENE ELD 45 SW JAN 10 NW MCB 40 SSW HEZ. THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 30 NNW BVE 55 N CLL 45 W SJT 15 W BGS 25 NNW AMA 30 WNW AKO 81V 70 SSE GDV DIK 30 NE HON 10 NE FOD 40 WSW OTM 35 W COU 25 ESE FYV 10 NNE HOT 20 ENE GLH 15 NE 0A8 30 ESE ATL 20 S GSP CLT SOP 25 S ILM ...CONT... MLB PIE. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 40 E PSX 35 NNW NIR 70 W COT ...CONT... 25 SSW P07 30 NNE CAO 10 WSW PUB 20 SE MTJ 40 NE U17 25 SW PGA 55 WSW GCN 40 WSW EED 40 WSW DAG 35 SW BFL 10 ENE PRB 20 NNE SJC 40 N UKI 20 SW MFR 50 SW S80 40 SE S06 40 NW CTB ...CONT... 15 E INL MSP 25 SW BRL 25 SSW BLV 20 NNE DYR 35 ESE MKL 25 W TYS 25 ENE LOZ 50 NNW JKL 45 SW CMH 25 NNE CMH 35 WNW PIT LBE 25 NW MRB 40 SW DCA 25 ENE RIC 35 NE ORF. LARGE SCALE PATTERN WILL CONTINUE TO AMPLIFY DURING THE PERIOD...AS STRONG UPPER TROUGH DIGS ESEWD INTO THE SWRN U.S. AND DOWNSTREAM SHORTWAVE RIDGE BUILDS OVER THE SRN HIGH PLAINS. THIS WILL STRENGTHEN WNWLY FLOW ALOFT FROM THE RED RIVER VALLEY INTO THE CENTRAL GULF COAST REGION...PARALLEL TO SURFACE WARM FRONT/OUTFLOW BOUNDARY NOW BECOMING BETTER DEFINED FROM SRN MS INTO NRN TX. SLY LOW LEVEL FLOW WILL ALSO STRENGTHEN ACROSS MOST OF THE PLAINS STATES AHEAD OF APPROACHING UPPER SYSTEM...WITH SOME NWD PUSH EXPECTED TO NRN TX WARM FRONT. IN ADDITION...DRY LINE WILL BECOME ESTABLISHED ALONG THE LEE OF THE ROCKIES FROM WRN SD INTO WRN TX. ...NRN TX/SRN OK INTO THE LOWER MS RIVER VALLEY... CURRENT INDICATIONS SUGGEST ETA MAY BE TOO AGGRESSIVE WITH ITS WARM FRONT POSITION LATER TODAY...WITH ACTUAL WARM FRONT LIKELY EXTENDING NEARER AVN FORECAST FROM THE ERN TX PANHANDLE SEWD TO NEAR ARKLATEX AREA BY THE EARLY EVENING. OUTFLOW FROM ONGOING STRONG/SEVERE MCS OVER FAR SRN AL WILL REINFORCE ERN EXTENT OF SURFACE FRONT POSITION FROM SRN AL/FL PANHANDLE ACROSS SRN MS. AIR MASS REMAINS VERY MOIST ACROSS WARM SECTOR WITH SURFACE DEW POINTS IN THE LOWER 70S LIKELY AS FAR NW AS N-CENTRAL TX/FAR SRN OK THIS AFTERNOON. CAP WILL LIKELY WEAKEN ALONG THE LENGTH OF THE FRONT... WHICH IS OVERRIDDEN BY MODERATE WNWLY FLOW ALOFT. CONVECTIVE SCENARIO MAY BE TRICKY...HOWEVER...AS WEAK DISTURBANCES REMAIN ILL- DEFINED WITHIN WNWLY FLOW. EXPECT AN AREA OF CONVECTION TO DEVELOP NEAR THE RED RIVER VALLEY BY 21Z...WHICH WILL QUICKLY BECOME SEVERE GIVEN THE STRONG INSTABILITY IN PLACE. THIS ACTIVITY SHOULD EVOLVE INTO SEVERAL SUPERCELLS AND LIKELY BECOME QUASI-LINEAR IN STRUCTURE DURING THE EVENING...POSSIBLY ORGANIZING INTO A FORWARD PROPAGATING MCS INTO NERN TX/SRN AR/NRN LA. SEVERE THUNDERSTORMS ARE EXPECTED TO BE WIDESPREAD ALONG THIS CORRIDOR. ADDITIONAL SEVERE THUNDERSTORM DEVELOPMENT MAY OCCUR INTO THE ARKLATEX REGION AND INTO LA/SRN MS DURING THE MID/LATE AFTERNOON...IN THE FORM OF SUPERCELLS AND SMALL LINES AS CAP WEAKENS ALONG THE LENGTH OF THE BOUNDARY AND STRONG INSTABILITY DEVELOPS. ...CENTRAL/SRN HIGH PLAINS INTO THE CENTRAL PLAINS... DRY LINE WILL LIKELY BECOME WELL ESTABLISHED FROM WRN SD ACROSS THE NEB PANHANDLE/ERN CO INTO THE ERN TX PANHANDLE TODAY. THIS AREA WILL ALSO REMAIN NORTH OF SHORTWAVE RIDGING OVER MUCH OF WRN TX... AND LARGE SCALE ASCENT/CONVERGENCE IS EXPECTED TO BECOME INCREASINGLY FAVORABLE FOR DIURNAL THUNDERSTORM DEVELOPMENT. SURFACE DEW POINTS IN THE LOWER 50S ARE EXPECTED AS FAR NORTH AS WRN SD...WITH MID 60S POSSIBLY INTO NWRN TX/ERN TX PANHANDLE BY AFTERNOON. RESULTANT MLCAPES ARE THEREFORE FORECAST OVER 1000 J/KG ALONG NRN PORTION OF SLIGHT RISK...AND MAY EXCEED 2500 J/KG INTO THE SRN HIGH PLAINS. AS CAP WEAKENS...SEVERAL AREAS OF DEEP MOIST CONVECTION ARE EXPECTED AFTER 21Z. LOW AND DEEP LAYER SHEAR WILL BE IMPRESSIVE ALONG MUCH OF THE DRY LINE WITH SFC-6 KM SHEAR IN EXCESS OF 70 KT...SUGGESTING SEVERAL TORNADIC SUPERCELLS MAY EVOLVE. VERY LARGE HAIL WILL BE AN ADDITIONAL THREAT WITHIN VERY STEEP LAPSE RATES. STORMS SHOULD BECOME ELEVATED/DEVELOP EWD AS LLJ AMPLIFIES DURING THE EVENING...WHICH WILL SPREAD A THREAT OF LARGE HAIL OVER MUCH OF THE CENTRAL PLAINS AFTER DARK. ...SOUTHEAST/CAROLINAS... SURFACE FRONT REMAINS ANCHORED ACROSS NRN FL/FAR SRN GA...THOUGH RESIDUAL MOISTURE NORTH OF THE BOUNDARY SHOULD SUPPORT MODERATE INSTABILITY LATER TODAY. IN ADDITION...WEAK SHORTWAVE TROUGH NOW MOVING ACROSS AL WILL LIKELY SUPPORT AFTERNOON CONVECTION... INCLUDING A FEW SEVERE THUNDERSTORMS GIVEN THE MODEST INSTABILITY AND SHEAR...AS STORMS SPREAD TOWARDS THE COAST DURING THE EVENING. ...CENTRAL APPALACHIANS... SHORTWAVE TROUGH NOW OVER IL/IND WILL AMPLIFY AS IT APPROACHES WV TODAY...AND MAY SUPPORT NUMEROUS THUNDERSTORMS INTO THE CENTRAL APPALACHIANS TODAY AND TONIGHT. THOUGH HAIL SHOULD ACCOMPANY STRONGER STORMS...OVERALL INSTABILITY IS NOT FORECAST TO SUPPORT MORE THAN ISOLATED SEVERE THUNDERSTORMS. ..EVANS.. 05/03/03