STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK DAY 1 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWE46 KWBC. VALID 241300Z - 251200Z THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING FOR EASTERN OKLAHOMA...EXTREME SOUTHEAST KANSAS...EXTREME NORTHEAST TEXAS...ARKANSAS...AND THE SOUTHERN HALF OF MISSOURI TO THE RIGHT OF A LINE FROM 25 SSE BLV 20 W PAH MEM 25 SSW GLH 40 NNE TYR 20 NNE DUA 40 N BVO 35 ENE JEF 25 SSE BLV. THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 45 SW GLS 35 SSE TPL 30 SE SJT 30 S END 35 NE P28 30 WNW SLN 15 ESE FNB 10 NE UIN 20 N CMI 25 ESE IND 25 S SDF 35 S BNA 10 SSE TCL 20 SSW MOB. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 40 SW PSX 45 NNW VCT 20 WSW AUS JCT 35 SW SJT 40 SW END 40 NNW DDC 10 SSE HLC GRI 15 W SPW 20 ESE MSP 55 SW IWD 40 W MQT 55 WNW PLN 35 WSW APN 25 E FNT 20 SE FDY 40 SSE LUK 35 W LOZ 30 NNW CHA 15 SSW GAD 20 SE SEM 20 WSW PNS. ...SYNOPSIS... STRONG VORTICITY MAXIMUM OVER SOUTHERN NEW MEXICO WILL LIFT NORTHEAST ACROSS THE CENTRAL AND SOUTHERN PLAINS OVER THE NEXT 24 HOURS. ASSOCIATED CYCLOGENESIS IS ALREADY UNDERWAY IN SOUTHEAST COLORADO...WITH DEEP LOW EXPECTED TO TRACK ACROSS KANSAS/IOWA/ WISCONSIN DURING THE PERIOD. BY EARLY THIS EVENING...THE COLD FRONT SHOULD EXTEND FROM THE LOW CENTER NEAR OMAHA NEBRASKA THROUGH WESTERN MISSOURI INTO EAST TEXAS. ...SOUTHERN PLAINS AND MIDDLE/LOWER MISSISSIPPI RIVER VALLEY... STRONG QG-FORCING WILL SPREAD NORTHEAST ACROSS THE AREA TODAY AND TONIGHT...EVIDENT IN 06Z ETA FORECAST 12 HOUR 500 MB HEIGHT FALL CENTER IN EXCESS OF 200 METERS SPREADING FROM KANSAS TO WISCONSIN. 12Z SOUNDINGS FROM OUN/LZK/SHV HAVE STRONG LOW LEVEL SHEAR...WITH ESTIMATED 0-3 KM STORM RELATIVE HELICITY VALUES OF 600-700 M2/S2 IN WARM ADVECTION REGIME. MID LEVEL LAPSE RATES ARE RATHER STEEP FROM SGF SOUTHWESTWARD INTO TEXAS...WITH 700-500 MB VALUES OF 7.5 TO 8.5 C/KM. THIS HAS RESULTED IN MODERATE ELEVATED INSTABILITY AT OUN/SHV WITH MUCAPE OF 1000-1300 J/KG. MAIN FORECAST PROBLEM WITH THIS SYSTEM IS STABLE BOUNDARY LAYER FROM CENTRAL OKLAHOMA AND ARKANSAS ON NORTH. RAPID LOW LEVEL ADVECTIONS WILL BRING 60S F DEWPOINTS NORTHWARD ACROSS MUCH OF EASTERN OKLAHOMA DURING THE DAY...BUT UNCERTAINTY ABOUT SURFACE BASED INSTABILITY EXISTS OVER SOUTHEAST KANSAS AND WESTERN MISSOURI. PRESENCE OF STRONG WIND FIELDS...SUFFICIENT SHEAR FOR SUPERCELLS/TORNADOES...STEEP MID LEVEL LAPSE RATES...AND STRONG QG- FORCING WITH DEEPENING CYCLONE INDICATE POTENTIAL FOR WIDESPREAD DAMAGING WINDS AND SOME TORNADOES. INITIAL MCS SHOULD LIFT NORTHEAST ACROSS TEXAS INTO PORTIONS OF MISSOURI AND IOWA DURING THE MORNING. NEW CONVECTION CURRENTLY DEVELOPING ALONG THE COLD FRONT/DRYLINE OVER WEST TEXAS SHOULD GRADUALLY INCREASE AS IT MOVES EASTWARD INTO MOISTURE AXIS BY THE MIDDAY HOURS. A SQUALL LINE WITH INCREASING POTENTIAL FOR DAMAGING WINDS AND LARGE HAIL SHOULD MOVE INTO EASTERN OKLAHOMA AND NORTHEAST TEXAS BY THE EARLY AFTERNOON HOURS...THEN SPREAD RAPIDLY EAST ACROSS MISSOURI/ARKANSAS/LOUISIANA DURING THE EVENING HOURS. EMBEDDED BOW ECHOES AND ISOLATED SUPERCELLS AHEAD OF THE LINE WILL HAVE ENHANCED POTENTIAL FOR TORNADO PRODUCTION. A GRADUAL WEAKENING TREND IS ANTICIPATED AFTER 06Z AS THE ACTIVITY CROSSES THE MISSISSIPPI RIVER. HOWEVER...DAMAGING WINDS WILL REMAIN POSSIBLE THROUGH THE NIGHT GIVEN THE STRENGTH OF THE LOW LEVEL WIND FIELDS AND DYNAMIC FORCING. ...EASTERN KANSAS/NORTHERN MISSOURI... DURING THE AFTERNOON AND EARLY EVENING HOURS...THUNDERSTORMS WILL LIKELY DEVELOP BENEATH THE COLD CORE UPPER TROUGH WHERE LAPSE RATES WILL BE STEEPEST. COMBINATION OF STRONG VERTICAL WIND SHEAR...SBCAPE OF 500-1000 J/KG...AND WET BULB ZERO HEIGHTS OF 4000 TO 6000 FEET AGL SUGGEST THUNDERSTORMS WITH MARGINALLY SEVERE HAIL ARE POSSIBLE. ..CRAVEN.. 02/24/01