The SPC is forecasting ...severe thunderstorms expected over parts of the southern plains this afternoon and tonight.... Please read the latest public statement about this event.
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SPC AC 090600 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0100 AM CDT TUE JUN 09 2009 VALID 091200Z - 101200Z ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF KANSAS... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL AND SRN PLAINS...OZARKS AND MID-MS VALLEY... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF NEW YORK...ERN PA...MD AND NJ... ...CNTRL AND SRN PLAINS... SOUTHWEST FLOW WILL BE IN PLACE ACROSS THE CNTRL PLAINS TODAY AS A 60 TO 70 KT MID-LEVEL JET MAX APPROACHES THE REGION FROM THE SOUTHWEST. AT THE BEGINNING OF THE PERIOD...AN MCS WITH ELEVATED THUNDERSTORMS SHOULD BE ONGOING IN WRN KS WITH THIS CONVECTIVE SYSTEM MOVING EWD ACROSS CNTRL AND ERN KS BY EARLY AFTERNOON. IN THE WAKE OF THE MCS...STRONG DESTABILIZATION SHOULD OCCUR ALONG A MOIST AXIS WITH SFC DEWPOINTS IN THE LOWER 70S F EXTENDING NNWWD FROM CNTRL OK INTO WCNTRL KS. NAMKF FORECAST SOUNDINGS ALONG THIS CORRIDOR BY 00Z SHOW EXTREME INSTABILITY IN CNTRL OK WITH MLCAPE VALUES APPROACHING 5000 J/KG. FURTHER NORTHWEST...MLCAPE VALUES DROP INTO THE 3000 TO 4000 J/KG RANGE INTO NW KS. IN ADDITION...THE MID-LEVEL JET MAX SHOULD MOVE OVER THE INSTABILITY AXIS DURING THE LATE AFTERNOON AND EARLY EVENING CREATING STRONG VERTICAL SHEAR PROFILES WITH 0-6 KM SHEAR VALUES IN THE 50 TO 60 KT RANGE. THIS ENVIRONMENT WILL BE A VERY FAVORABLE RAPID SUPERCELL DEVELOPMENT ONCE SFC-BASED STORMS INITIATE JUST WEST OF THE MODERATE RISK AREA IN THE LATE AFTERNOON OR EARLY EVENING. MODEL FORECASTS ARE IN AGREEMENT ORGANIZING A CLUSTER OF INTENSE THUNDERSTORMS IN NRN KS AND DRIVING A WELL-DEVELOPED MCS EWD ACROSS NERN KS INTO NRN MO OVERNIGHT. CONCERNING THE SEVERE THREATS...A 30 TO 40 KT LOW-LEVEL JET WILL INCREASE FROM NRN OK INTO CNTRL KS DURING THE EARLY EVENING FEEDING INTO SUPERCELLS ONGOING IN THE NRN PART OF THE MODERATE RISK AREA. FORECAST SOUNDINGS AROUND HUTCHINSON KS AT 00Z SHOW IMPRESSIVE LOW-LEVEL SHEAR WITH SUBSTANTIAL DIRECTIONAL SHEAR BELOW 800 MB AND 0-1 KM SHEAR VALUES OF 25 KT. THIS COMBINED WITH LCL HEIGHTS AROUND 500 METERS WILL BE FAVORABLE FOR TORNADOES WITH SUPERCELLS THAT TRACK EWD ACROSS THE MODERATE RISK AREA. WITH THIS VERY FAVORABLE ENVIRONMENT IN PLACE...THE POTENTIAL EXISTS FOR A FEW LONG TRACK SUPERCELLS CAPABLE OF PRODUCING ISOLATED STRONG TORNADOES. THE CORRIDOR WITH THE GREATEST THREAT FOR STRONG TORNADOES SHOULD EXIST FROM HAYS KS EWD ALONG THE I-70 CORRIDOR TO MANHATTAN KS AND SWD ALONG THE I-35 CORRIDOR. SUPERCELLS SHOULD BE MORE ISOLATED SWD INTO FAR SRN KS AND NRN OK WHERE A CAPPING INVERSION WILL BE INCREASINGLY INFLUENTIAL. SUPERCELLS THAT DEVELOP IN THIS STRONG INSTABILITY SHOULD ALSO BE CAPABLE OF PRODUCING VERY LARGE HAIL. THE WIND DAMAGE THREAT SHOULD BE FOCUSED FURTHER EAST ACROSS ERN KS INTO NW MO AS THE MCS BECOMES WELL-DEVELOPED. ...NRN OZARKS/MID-MS VALLEY/SRN OH VALLEY... AN AXIS OF MODERATE TO STRONG INSTABILITY IS FORECAST ACROSS MO EXTENDING EWD INTO THE SRN OH VALLEY. MODEL FORECASTS AGREE WITH DEVELOPING SCATTERED TO NUMEROUS THUNDERSTORMS BY LATE THIS AFTERNOON. THIS DEVELOPMENT SHOULD BE STRONGLY TIED TO SFC HEATING. FORECAST SOUNDINGS AT 21Z ACROSS SRN MO INTO WRN KY SHOW MODERATE VERTICAL SHEAR PROFILES SUGGESTING ISOLATED SUPERCELLS AND/OR ORGANIZED BOWING LINE-SEGMENTS WILL BE POSSIBLE. THE STRONG INSTABILITY SHOULD BE ADEQUATE FOR LARGE HAIL WITH THE MORE INTENSE STORMS. IN ADDITION...LOW-LEVEL LAPSE RATES WILL BE QUITE STEEP SUGGESTING A THREAT FOR ISOLATED WIND DAMAGE WILL ALSO EXIST. ...NY/ERN PA/MD... A WELL-DEFINED MOIST AXIS WILL BE IN PLACE TODAY FROM THE MID-ATLANTIC NEWD ACROSS ERN PA INTO CNTRL NY. THE MODELS DEVELOP MODERATE INSTABILITY ALONG THE CORRIDOR WITH STORMS INITIATING IN THE HIGHER TERRAIN OF ECNTRL PA AND SRN NY. FORECAST SOUNDINGS LATE THIS AFTERNOON ALONG THIS CORRIDOR SHOW 0-6 KM SHEAR VALUES IN THE 35 TO 40 KT RANGE SUGGESTING SHEAR WILL BE FAVORABLE FOR ORGANIZED SEVERE STORMS. THE LATEST NAM AT 18Z SHOWS 0-3 KM LAPSE RATES OF 8.5 TO 9.5 C/KM SUGGESTING DOWNDRAFT MOMENTUM WILL BE QUITE EFFICIENT AND FAVORABLE FOR WIND DAMAGE. HAIL WILL ALSO BE LIKELY WITH THE MORE INTENSE CELLS GIVEN THE AMOUNT OF INSTABILITY FORECAST. ..BROYLES.. 06/09/2009 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z