The SPC is forecasting ...significant severe thunderstorms expected over parts of the central and southern plains this afternoon and tonight.... Please read the latest public statement about this event.
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SPC AC 091628 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1128 AM CDT TUE JUN 09 2009 VALID 091630Z - 101200Z ...THERE IS A MDT RISK OF SVR TSTMS ACROSS S CENTRAL/SE KS INTO EXTREME NRN OK AND SW MO THROUGH LATE EVENING... ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK AREA...FROM NE CO AND NW TX EWD TO THE OH VALLEY...APPALACHIANS...AND S CENTRAL NY... ...CENTRAL/SRN PLAINS AREA THROUGH TONIGHT... AN ONGOING CLUSTER OF SLIGHTLY ELEVATED THUNDERSTORMS APPEARS TO BE IN THE PROCESS OF EVOLVING INTO A FORWARD-PROPAGATING MCS FROM ERN KS INTO WRN MO. GIVEN A FEED OF STRONG INSTABILITY FROM THE SW AND LOW-LEVEL DESTABILIZATION ASSOCIATED WITH DAYTIME HEATING AND NWD PROGRESS OF THE WARM FRONT FROM OK/AR INTO SE KS/SW MO...THIS CONVECTION WILL LIKELY BECOME ROOTED NEAR THE GROUND WITH AN INCREASING WIND DAMAGE THREAT THROUGH THE AFTERNOON AS THE COLD POOL STRENGTHENS. OUTFLOW FROM THIS CONVECTION IS ALSO MOVING SWD ACROSS CENTRAL KS AND WILL CROSS SE KS EARLY THIS AFTERNOON...AS THE WARM FRONT LIFTS NWD. THE NET RESULT SHOULD BE CONSOLIDATION OF A PRONOUNCED BAROCLINIC ZONE FROM SW MO ENEWD INTO SE KS...AND THEN WWD INTO S CENTRAL KS. ADDITIONAL SURFACE-BASED THUNDERSTORMS WILL LIKELY FORM AROUND MID AFTERNOON ALONG THE OUTFLOW BOUNDARY AND NEAR THE TRIPLE POINT WITH THE DRYLINE ACROSS SRN KS AND PERHAPS EXTREME NRN OK. CONTINUED DAYTIME HEATING /TEMPERATURES WARMING TO THE UPPER 80S TO LOWER 90S/ AND BOUNDARY LAYER DEWPOINTS OF 68-70 F...BENEATH STEEP MID LEVEL LAPSE RATES...WILL CONTRIBUTE TO STRONG INSTABILITY /MLCAPE VALUES AOA 3000 J/KG/ AND WEAKENING CONVECTIVE INHIBITION. MEANWHILE...DEEP LAYER VERTICAL SHEAR WILL REMAIN FAVORABLE FOR SUPERCELLS...AS SOME INCREASE IN MID LEVEL FLOW SHOULD OCCUR IN CONJUNCTION WITH A SUBTLE SPEED MAX EJECTING NEWD FROM NM IN ADVANCE OF THE PRIMARY MID LEVEL TROUGH OVER THE SWRN STATES. FORECAST SOUNDINGS E OF THE TRIPLE POINT AND NEAR THE OUTFLOW/WARM FRONT SHOW FAVORABLE PROFILES FOR SUPERCELLS CAPABLE OF PRODUCING VERY LARGE HAIL...DAMAGING WINDS...AND ISOLATED STRONG TORNADOES. THE AFTERNOON CONVECTION MAY GROW INTO ANOTHER MCS OVERNIGHT AND SPREAD EWD ACROSS MO IN ASSOCIATION WITH AN INCREASE IN THE LLJ AND WAA OVER THE REMNANT COLD POOL FROM THE ONGOING ACTIVITY IN KS/MO. FARTHER S...AS DURING PREVIOUS DAYS...STRONG SURFACE HEATING COULD SUPPORT ISOLATED THUNDERSTORM DEVELOPMENT ALONG THE DRYLINE IN TX. IF STORMS FORM...ISOLATED LARGE HAIL AND DAMAGING WINDS CAN BE EXPECTED. ...OH VALLEY/APPALACHIANS AREA TO CENTRAL NY THIS AFTERNOON... COMPLICATED FORECAST TODAY WITH SEVERAL SMALL SCALE SPEED MAXIMA PROGRESSING EWD FROM THE OH VALLEY TO THE APPALACHIANS...S OF THE MAIN BELT OF WLYS AND THE PRIMARY SHORTWAVE TROUGH NEAR AND N OF THE SAINT LAWRENCE VALLEY. AT THE SURFACE...A COLD FRONT IS MOVING SLOWLY EWD INTO WRN NY/PA AND SEWD TOWARD THE OH RIVER...WHILE A WARM FRONT IS LIFTING SLOWLY NEWD ACROSS ERN PA AND SRN/SERN NY. REGIONAL 12Z SOUNDINGS REVEAL RELATIVELY STEEP MID LEVEL LAPSE RATES AND POTENTIALLY MODERATE INSTABILITY /MLCAPE VALUES OF 1500-2500 J/KG/ ONCE AFTERNOON TEMPERATURES WARM INTO THE UPPER 70S ACROSS NY ...THE LOW-MID 80S TOWARD THE OH VALLEY...AND THE UPPER 80S IN THE LEE OF THE CENTRAL/SRN APPALACHIANS. THERE WILL BE THE POTENTIAL FOR SCATTERED THUNDERSTORM DEVELOPMENT THIS AFTERNOON ALONG THE SURFACE FRONT AND IN ADVANCE OF THE SUBTLE MID LEVEL SPEED MAXIMA FROM THE OH VALLEY NEWD INTO PA/NY. THE STRONGER LOW-MID LEVEL FLOW AND VERTICAL SHEAR WILL RESIDE OVER PA AND ESPECIALLY NY...WHERE ORGANIZED CLUSTERS/LINE SEGMENTS COULD PRODUCE DAMAGING WINDS AND LARGE HAIL. FARTHER S AND SW TOWARD THE OH VALLEY AND APPALACHIANS...DIURNAL PULSE-TYPE CONVECTION WILL BE CAPABLE OF PRODUCING DAMAGING DOWNBURST WINDS AND LARGE HAIL IN THE RELATIVELY WEAK VERTICAL SHEAR ENVIRONMENT. ...SE FL COAST THIS AFTERNOON... WITH WEAK MEAN NWLY FLOW IN THE LOW-MID LEVELS...THE SE FL SEA BREEZE SHOULD REMAIN ANCHORED CLOSE TO THE COAST THIS AFTERNOON. THE THERMODYNAMIC ENVIRONMENT WILL AGAIN BE SUPPORTIVE OF ISOLATED DAMAGING WET MICROBURSTS AND MARGINALLY SEVERE HAIL. ..THOMPSON/GARNER.. 06/09/2009 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z