The SPC is forecasting ...severe thunderstorms expected over parts of the southern plains today.... Please read the latest public statement about this event.
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SPC AC 311559 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1059 AM CDT MON MAR 31 2008 VALID 311630Z - 011200Z ...THERE IS A MDT RISK OF SVR TSTMS ACROSS NRN TX...SRN/ERN OK...WRN AR AND SWRN MO... ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MODERATE RISK AREA TX NEWD INTO IA/IL... ...SYNOPSIS... A SURFACE CYCLONE WAS MOVING INTO NWRN MO AT MID MORNING AND IS FORECAST TO MOVE NEWD INTO THE GREAT LAKES AREA BY LATE TONIGHT ...AS PRIMARY MID LEVEL TROUGH EJECTS FROM CO/NM AREA NEWD INTO THE UPPER MS VALLEY. THIS WILL AID IN PUSHING A TRAILING COLD FRONT EWD ACROSS THE MID/UPPER MS VALLEY AND SWD INTO NRN/CENTRAL TX BY MORNING. ALSO...A DRYLINE WILL SHIFT EWD FROM WRN TX INTO THE CENTRAL TX THIS AFTERNOON. ...OK/SRN MO/SERN KS/AR... MORNING ANALYSIS SHOWED THE RICHER GULF MOISTURE RETURN WAS CONFINED MAINLY ACROSS THE WARM SECTOR IN OK/TX...WITH DEWPOINTS IN THE MID AND UPPER 60S. THIS MOISTURE WAS FEEDING SEVERE STORMS OVER SWRN MO/SERN KS THIS MORNING...WITH OTHER CONVECTION DEVELOPING ALONG/AHEAD OF THE COLD FRONT ACROSS PORTIONS OF OK. ONLY WEAK CAPPING WAS INDICATED ON THE OKC/SGF 12Z SOUNDINGS...SO WEAK DIURNAL HEATING AND DYNAMICAL FORCING ASSOCIATED WITH MID LEVEL SHORTWAVE TROUGH SHOULD PROVIDE A FAVORABLE ENVIRONMENT FOR INTENSE STORMS TO DEVELOP AHEAD OF THE FRONT DURING THE DAY. THE GREATEST SEVERE THREAT THIS AFTERNOON IS EXPECTED ACROSS SRN/ERN OK AND WRN AR...WHERE THE BEST COMBINATION OF DIURNAL HEATING... INSTABILITY/MLCAPES 1500-2500 J/KG/ AND DYNAMICAL FORCING WILL BE THE STRONGEST. EFFECTIVE SHEAR AT 40-50 KT WILL BE FAVORABLE FOR SUPERCELLS...AND STEEP MID LEVEL LAPSE RATES SHOULD RESULT IN NUMEROUS STORMS WITH LARGE HAIL. ALSO...THE STRENGTH OF THE LOW LEVEL SHEAR/SRH FROM 250-350 M2/S2 AND DEPTH OF MOIST BOUNDARY LAYER INDICATES TORNADOES ARE LIKELY...SOME STRONG...ESPECIALLY ACROSS THE MODERATE RISK AREA. ...CENTRAL TX... OTHER THUNDERSTORM ARE LIKELY TO DEVELOP ALONG THE DRYLINE FROM NEAR FSI TO BWD...AND POSSIBLY AS FAR SWWD AS DRT...THIS AFTERNOON. STRONG HEATING IS ALREADY OCCURRING EAST OF THE DRYLINE...WITH READINGS EXPECTED TO CLIMB INTO MID/UPPER 80S BY MID AFTERNOON. THIS HEATING AND DEWPOINTS IN THE MID 60S SHOULD YIELD MLCAPES FROM 2000-3000 J/KG. THE ENVIRONMENT WILL BE SUPPORTIVE OF DISCRETE SUPERCELLS WITH VERY STEEP MID/HIGH LEVEL LAPSE RATES MOST FAVORABLE FOR VERY LARGE HAIL. HOWEVER...GIVEN THE AMOUNT OF INSTABILITY AND RELATIVELY STRONG LOW LEVEL SHEAR...TORNADOES ARE ALSO POSSIBLE. THE STORMS SHOULD PUSH EWD ACROSS THE REST OF AR/ERN TX AND NWRN LA OVERNIGHT...BUT SHOULD GRADUALLY WEAKEN AS THEY MOVE INTO A LESS UNSTABLE ENVIRONMENT AND THE MAIN FORCING LIFTS NORTH OF THIS AREA. ...NRN MO/SE IA/IL/FAR SRN WI... DRIER LOW-LEVEL TRAJECTORIES AND CONSIDERABLE CLOUDS/PCPN SUGGEST THAT INSTABILITY WILL BE WEAKER FROM CENTRAL MO NEWD TO THE WRN GREAT LAKES. THIS MAY RESULT IN LESS SEVERE STORMS THAN ACROSS THE SRN PLAINS...DESPITE STRONGER DYNAMICAL FORCING/SURFACE LOW TRACK. HOWEVER...WHERE HEATING OCCURS...THE VERTICAL SHEAR WILL BE FAVORABLE FOR SUPERCELLS AND POSSIBLY TORNADOES. ..IMY/JEWELL.. 03/31/2008 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z