The SPC is forecasting ...severe thunderstorms expected over parts of the central and southern plains.... Please read the latest public statement about this event.
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SPC AC 231536 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1036 AM CDT MON MAR 23 2009 VALID 231630Z - 241200Z ...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF CNTRL AND ERN KS AND NRN OK... ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK AREA FROM N TX INTO MID MO AND MID MS VLYS... OVERALL SCENARIO DISCUSSED IN PRIOR/13Z/ DY1 OUTLOOK IS ON TRACK. INTENSE UPPER VORT/LOW BECOMING VERTICAL WITH STRONG SURFACE LOW SWRN NEB AND TRACKS NEWD INTO SERN SD BY 12Z TUE. 50-60KT LLJ CONTINUES TO STREAM A MOIST AND INCREASINGLY UNSTABLE AIRMASS NWD AHEAD OF THE COLD FRONT DRY LINE WHICH EXTENDS SWD FROM LOW CENTER THRU WRN KS INTO TX PANHANDLE ATTM. STRONG ASCENT AND MID LEVEL COOLING WILL QUICKLY ERODE THE CINH OVER NEB INTO SRN SD AHEAD OF LOW WITH SEVERE THUNDERSTORMS DEVELOPING BY EARLY AFTERNOON. FURTHER S INTO KS AND OK SEVERE THUNDERSTORMS WILL GRADUALLY FORM LATER THIS AFTERNOON AS HEATING AND ASCENT REMOVE THE CURRENT SUBSTANTIAL INHIBITION. ...S CNTRL/ERN SD SWD INTO CNTRL/ERN NEB AND N CNTRL KS TODAY... REF MCD 238 ALTHOUGH BOUNDARY LAYER MOISTURE WILL REMAIN COMPARATIVELY LIMITED /SFC DEWPOINTS IN THE LOW 50S/...WITH 500 MB TEMPS AROUND MINUS 20 C...MODEST SFC HEATING SHOULD BOOST SBCAPE TO AOA 500 J/KG. COMBINATION OF DESTABILIZATION AND INCREASING ASCENT WILL SUPPORT TSTM DEVELOPMENT ALONG COLD FRONT/OCCLUSION BY 18Z THROUGH LATE THIS AFTN FROM S CNTRL SD ACROSS CNTRL NEB INTO N CNTRL KS. DEEP SHEAR WILL BE STRONG /40-50 KTS/ THROUGHOUT REGION...ALTHOUGH WITH A SUBSTANTIAL COMPONENT ORIENTED PARALLEL TO FRONT IN SD AND NEB. OVERALL SETUP SHOULD YIELD A FEW SUSTAINED STORMS WITH A THREAT FOR SVR HAIL/WIND. ASSUMING THE PRESENCE OF SUSTAINED UPDRAFTS...BACKED LOW-LVL FLOW NE OF SFC LOW IN NRN NEB AND SRN SD ALSO WILL BE FAVORABLE FOR LOW LVL STORM ROTATION/TORNADOES ...BEFORE FRONT AND DEEP ASCENT OUTRUN LOW LVL MOIST AXIS LATE IN THE DAY. VERTICAL SHEAR PROFILES WILL BE MORE CONDUCIVE FOR TORNADIC SUPERCELLS WITH SWD EXTENT AND THE TORNADO PROBABILITIES HAVE BEEN INCREASED ACCORDINGLY NWD INTO SERN NEB. ..CNTRL/ERN KS SSW INTO MUCH OF OK/NW TX LATE TODAY/TONIGHT... DEEP FORCING FOR ASCENT AND MID LVL COOLING WILL REMAIN WEAK FROM CNTRL KS SW ACROSS OK AND NW TX TODAY AS LEAD SPEED MAX/UPR VORT LIFT NE INTO NEB/SD. COUPLED WITH RELATIVELY LIMITED BOUNDARY LAYER MOISTURE AND SUBSTANTIAL EML CAP ON S SIDE OF UPR JET...EXPECT LITTLE IF ANY TSTM DEVELOPMENT TIL LATE IN THE DAY OVER OK AND NW TX. SCTD STORMS MAY...HOWEVER...CONTINUE TO DEVELOP SLOWLY SWD ALONG FRONT IN KS. BY EARLY EVE...ASCENT WITH UPSTREAM JET DISTURBANCE SHOULD BEGIN TO OVERSPREAD THE SRN PLNS AS COLD FRONT OVERTAKES PRE-FRONTAL TROUGH/DRY LINE. COMBINATION OF STRENGTHENING ASCENT WITH SLOWLY INCREASING BOUNDARY LAYER MOISTURE /SFC DEWPOINTS IN THE UPR 50S TO NEAR 60 F/ MAY SUPPORT INCREASED STORM COVERAGE/STRENGTH ALONG THE FRONT IN KS...AND DEVELOPMENT OF OTHER STORMS SW ALONG FRONT OR DRY LINE INTO OK. 50+ KT DEEP SHEAR OVER REGION WILL BE ORIENTED AT A CONSIDERABLE ANGLE TO THE FRONT. GIVEN SUSTAINED UPDRAFTS...THIS SHOULD ALLOW FOR THE DEVELOPMENT OF ELONGATED SUPERCELL STRUCTURES WITH A GOOD THREAT FOR LARGE HAIL AND HIGH WIND. IN ADDITION...35-40 KT 0-1 KM SHEAR WITH A SUBSTANTIAL DIRECTIONAL COMPONENT /ASSOCIATED WITH 60KT SSWLY LOW LVL JET/...SUGGESTS POTENTIAL FOR STRONG TORNADOES ...IF SUSTAINED SEMI-DISCRETE STORMS DO INDEED FORM. ..HALES/JEWELL.. 03/23/2009 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z