The SPC is forecasting ...severe thunderstorms expected over parts of the ohio valley this afternoon and early evening.... Please read the latest public statement about this event.
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SPC AC 101631 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1131 AM CDT THU AUG 10 2006 VALID 101630Z - 111200Z ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY TONIGHT ACROSS PARTS OF THE MID MS AND LOWER OH VALLEY REGION... ...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON/EVENING FROM WRN ND INTO NRN NEB... ...IL/INDIANA/KY/SW OH THIS AFTERNOON... THE EARLIER BOW ECHO OVER NRN IL HAS BECOME RATHER DISORGANIZED THE PAST 1-2 HOURS WHILE PROGRESSING INTO NW/W CENTRAL INDIANA. OTHER LEAD CONVECTION HAS GENERATED OUTFLOW THAT IS MOVING S IN ADVANCE OF THE ORIGINAL BOW...WHILE ANOTHER OUTFLOW BOUNDARY IS MOVING SEWD ACROSS CENTRAL IL. THE ONGOING STORMS REMAIN SLIGHTLY ELEVATED OVER IL/INDIANA...AND REGIONAL 12Z SOUNDINGS SUGGEST THAT A TRANSITION TO TRULY SURFACE-BASED CONVECTION WILL LIKELY BE DELAYED UNTIL SURFACE TEMPERATURES WARM INTO THE 90S WITH DEWPOINTS REMAINING IN THE LOW-MID 70S. THOSE SAME SURFACE CONDITIONS WILL CONTRIBUTE TO STRONG INSTABILITY /MLCAPE VALUES AOA 3000 J/KG OVER SRN IL/INDIANA...WHERE CONVECTION MAY INTENSIFY THIS AFTERNOON ALONG THE OUTFLOWS FROM THE MORNING STORMS. DAMAGING WINDS CAN BE EXPECTED WITH THE MORE INTENSE STORMS THIS AFTERNOON...ALONG WITH ISOLATED/MARGINALLY SEVERE HAIL. HOWEVER...A POTENTIAL LIMITING FACTOR FOR A MORE WIDESPREAD/SIGNIFICANT WIND DAMAGE THREAT WILL BE RELATIVELY WEAK LOW-MID LEVEL FLOW NOTED IN VWP/S AND PROFILERS NEAR AND S OF THE ONGOING CONVECTION. THE COMPLEXITY INTRODUCED BY THE ONGOING CONVECTION CASTS DOUBT ON ANY DETAILS IN THE SHORT RANGE MODEL FORECASTS FOR THIS AFTERNOON/OVERNIGHT ACROSS THE MS/OH VALLEY REGION. THERE WILL BE SOME POSSIBILITY FOR RECOVERY IN THE WAKE OF THE MORNING STORMS AND IN ADVANCE OF THE CONVECTIVELY ENHANCED MID LEVEL WAVE OVER CENTRAL IA THAT SHOULD MOVE ESEWD THROUGH TONIGHT. HOWEVER...THE SITUATION IS COMPLICATED FURTHER BY THE ONGOING STORMS ACROSS CENTRAL/SRN MO IN ASSOCIATION WITH THE WEAK IMPULSE MOVING OVER SW MO. THIS MO CONVECTION WILL TEND TO DISRUPT DESTABILIZATION IN WHAT WOULD BE THE INFLOW SOURCE REGION FOR STORMS UPSTREAM FROM THE MORNING MCS/S. ONE OR MORE THUNDERSTORM CLUSTERS MAY PERSIST AND/OR FORM TONIGHT OVER THE MID MS/LOWER OH VALLEY REGION...BUT THE SEVERE THREAT SHOULD BE REDUCED BY THE STABILIZING EFFECTS OF ONGOING AND AFTERNOON CONVECTION. ...CENTRAL/NRN PLAINS THIS AFTERNOON/EVENING... A MID LEVEL TROUGH WITH EMBEDDED VORTICITY CENTERS FROM CO TO ERN MT IS BECOMING MORE DIFFUSE WITH TIME OVER THE HIGH PLAINS WHILE ENCOUNTERING THE LARGER SCALE RIDGE AXIS. THIS SERIES OF WAVES WILL OVERSPREAD WRN NEB AND THE WRN DAKOTAS THIS AFTERNOON. IN THE LOW LEVELS...A REMNANT LEE TROUGH EXTENDS FROM CENTRAL NEB ACROSS WRN SD INTO ERN MT. E OF THE LEE TROUGH...A SERIES OF OUTFLOWS FROM OVERNIGHT CONVECTION HAVE PUSHED SWD AND WWD ACROSS NEB AND THE DAKOTAS. VISIBLE SATELLITE IMAGERY SUGGESTS THAT SURFACE HEATING WILL BE STRONGEST ACROSS WRN SD...WITH CLOUDS PERHAPS LIMITING HEATING A LITTLE ACROSS WRN NEB AND WRN ND. A FEW STRONG/SEVERE STORMS SHOULD DEVELOP ALONG THE WRN EDGE OF THE INSTABILITY THIS AFTERNOON FROM SW ND ACROSS WRN SD...AND STORMS SHOULD MOVE SEWD THROUGH THIS EVENING. MODIFIED 12Z SOUNDINGS SUPPORT AFTERNOON MLCAPE VALUES OF 1500-2000 J/KG WITH RESIDUAL BOUNDARY LAYER DEWPOINTS IN THE 60S AND STEEP MID LEVEL LAPSE RATES. DEEP LAYER VERTICAL SHEAR MAY ALSO BE SUFFICIENT FOR SUPERCELLS...WHICH WOULD LOCALLY ENHANCE THE THREAT FOR LARGE HAIL. ..THOMPSON/GUYER.. 08/10/2006 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z