STORM PREDICTION CENTER...NWS/NCEP...NORMAN OK DAY 2 CONVECTIVE OUTLOOK...REF AWIPS GRAPHIC PGWI47 KWNS. VALID 191200Z - 201200Z THERE IS A MDT RISK OF SVR TSTMS IS FORECAST FROM SERN KS INTO N- CENTRAL TX...TO THE RIGHT OF A LINE FROM 25 WSW JLN 35 SSE MKO 20 WSW PRX 25 SE FTW 10 NE MWL 25 NE SPS 20 ESE CSM 45 ENE GAG 15 ENE P28 35 ENE ICT 15 NNW CNU 25 WSW JLN. THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 35 NE VIH 25 WNW LIT 65 SW TYR 30 NW SAT 15 ESE JCT 25 SSE ABI 45 SE CDS 45 SW GAG 25 S DDC 10 E RSL 45 SE OMA 10 S MCW 45 NNW EAU 35 SSE IWD 40 S ESC 20 NE MKE 30 ENE MLI 35 NE VIH. GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 35 NW DRT 35 SSE SJT 35 W ABI 40 NE PVW 65 NE 4CR 30 SW FMN 25 NNE CNY 40 NE RKS 25 SSE DGW 35 ESE AKO 55 WNW GCK 50 NNE DDC 35 E OLU 10 SSW YKN BKX 15 WNW DLH 115 NNE CMX ...CONT... 50 NNE APN 25 SW HTL 20 WNW BEH CMI 35 WNW MEM 20 W MLU 30 NW HOU 50 NW LRD. BROAD TROUGH OVER THE ROCKIES WILL AMPLIFY LATE IN THE DAY 1 FORECAST PERIOD...AS STRONG SHORTWAVE TROUGH AND ASSOCIATED MID/UPPER LEVEL SPEED MAX NOW OVER THE PAC NW DIG SSEWD INTO THE 4- CORNERS REGION. THIS SYSTEM WILL EJECT NEWD ACROSS THE SRN HIGH PLAINS SATURDAY...WITH STRONG MID LEVEL SPEED MAX SHIFTING ACROSS WRN TX AND EXTENDING INTO ERN OK. IN RESPONSE...A SURFACE LOW WILL DEEPEN OVER NWRN TX AND SHIFT ENEWD ALONG THE RED RIVER VALLEY DURING THE DAY...BEFORE LIFTING NEWD INTO MO OVERNIGHT. IN ADDITION...MID/UPPER LEVEL LOW WILL PERSIST OVER THE NRN PLAINS WHILE FAST MOVING SHORTWAVE TROUGH NOW OFF THE BAJA CA EJECTS NEWD INTO THE NRN MS RIVER VALLEY. ...SRN PLAINS... A FAIRLY MOIST BOUNDARY LAYER WILL UNDERGO FURTHER MOISTENING/ DEEPENING THROUGH THE DAY OVER THE SRN PLAINS...WITH AN AXIS OF 12C 850 MB DEW POINTS /SFC DEWPOINTS IN THE LOWER TO MID 60S F/ FORECAST OVER WRN/CENTRAL OK AND CENTRAL TX BY THE LATE AFTERNOON ALONG AND EAST OF THE DRY LINE. ELEVATED STRONG/SEVERE THUNDERSTORMS SHOULD BE ONGOING SATURDAY MORNING ALONG 45-55 KT SLY LLJ...AND MAY SUSTAIN A THREAT OF LARGE HAIL FOR MUCH OF THE DAY AS THEY SHIFT ENEWD AND ARE FED BY VERY STEEP LAPSE RATES ADVECTING NEWD OUT OF THE SRN HIGH PLAINS. CLEARING IN THE WAKE OF THIS ACTIVITY SHOULD SUPPORT STRONG HEATING WITH TEMPERATURES WELL IN THE 80S AHEAD OF EWD MOVING DRY LINE/SURFACE LOW AND SOUTH OF OUTFLOW BOUNDARY FROM MORNING MCS...WITH LAPSE RATES IN EXCESS OF 7.5 C/KM SUPPORTING STRONG INSTABILITY FROM W-CENTRAL OK INTO CENTRAL TX BY THE MID AFTERNOON. AS LARGE SCALE ASCENT AND STRENGTHENING SURFACE CONVERGENCE COUPLE OVER THE SRN PLAINS...THE POTENTIAL FOR WIDESPREAD DEEP MOIST CONVECTION WILL INCREASE...PRIMARILY ALONG AND NORTH OF MID LEVEL JET. SWD DEVELOPMENT ALONG DRY LINE INTO CENTRAL TX WILL BE MORE PROBLEMATIC DUE TO STRONG CAP AND LACK OF LARGE SCALE ASCENT OVER THIS REGION. HOWEVER...ENTIRE DRY LINE WILL REMAIN NORTH OF SUBTROPICAL UPPER JET AND WITHIN STRONG SHEAR/INSTABILITY WARRANTING A CONDITIONAL SLIGHT RISK WELL INTO TX. SHEAR PROFILES ARE EXPECTED TO BE SUFFICIENT FOR TORNADIC SUPERCELLS...ESPECIALLY WITH DISCRETE DEVELOPMENT INTO THE EARLY EVENING. MODELS MAY BE UNDERFORECASTING LOW LEVEL SHEAR AS ETA MAINTAINS 0-1 KM SHEAR AOB 10 KT OVER OK. LOW LEVEL SHEAR WILL LIKELY BE STRONGER NEAR THE SURFACE LOW/OUTFLOW BOUNDARY...AND AS SURFACE WINDS BACK WITHIN ANY PRESSURE FALL MAXIMA EAST OF THE DRY LINE DURING THE AFTERNOON. SEVERE THREAT WILL LIKELY DIMINISH SOME DURING THE MID/LATE EVENING AS AIR MASS BECOMES LESS UNSTABLE AND STORMS DEVELOP INTO ERN KS/ERN OK/NERN TX. HOWEVER AS MID/UPPER LEVEL TROUGH EJECTS NEWD TOWARDS MO...A FEW SEVERE THUNDERSTORMS WILL LIKELY CONTINUE DEVELOPING OVERNIGHT WITHIN REGION OF STRONG LARGE SCALE ASCENT. ...WI/IA... A SURFACE LOW IS FORECAST TO PERSIST AND LIFT SLOWLY NWD FROM SRN MN INTO NWRN WI DURING THE PERIOD...WITH SURFACE TROUGH/COLD FRONT SHIFTING SLY EWD INTO IA. FORECAST SHEAR PROFILES REMAIN SUFFICIENT FOR ORGANIZED CONVECTION /INCLUDING SUPERCELLS/ AS AIR MASS BECOMES MODERATELY UNSTABLE WITHIN THE WARM SECTOR DURING THE AFTERNOON. SEVERE THREAT OVER THIS REGION SHOULD SLOWLY DIMINISH DURING THE EVENING AS AIR MASS STABILIZES. ..EVANS.. 04/18/03