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 102004 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0304 PM CDT THU AUG 10 2006 VALID 102000Z - 111200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE OH/TN VLYS... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE CNTRL/NRN PLAINS... ...LWR OH/TN VLYS WWD TO THE CNTRL PLAINS... PRIMARY MID-LEVEL SPEED MAX CONTINUES TO TRANSLATE SEWD THROUGH THE MID-OH VLY WITH A WEAKER DISTURBANCE MOVING EWD THROUGH MO THIS AFTN. E-W ORIENTED BAND OF TSTMS THAT DEVELOPED ALONG THE SRN EDGE OF THE NOCTURNAL MCS...ASSCD WITH THE OH VLY IMPULSE... CONTINUES TO MOVE SSEWD INTO THE LWR OH VLY. THESE STORMS WILL CONTINUE TO MERGE WITH A N-S ORIENTED LINE OF STORMS FORMING AHEAD OF THE LATTER DISTURBANCE. AIR MASS DOWNSTREAM FROM BOTH LINE SEGMENTS REMAINS STGLY UNSTABLE WITH MLCAPES TO 3000 J/KG ACROSS SRN IND AND NWRN/W KY. STORMS ARE BEGINNING TO SINK S OF THE STRONGER WLYS WITH VERTICAL SHEAR DROPPING OFF CONSIDERABLY S OF THE OH RVR. BUT...WNWLY FLOW ALOFT AND THE STEEP LOW-LEVEL LAPSE RATES/BUOYANCY IN PLACE DOWNSTREAM SHOULD CONTINUE TO SUPPORT MAINLY A DAMAGING WIND THREAT THROUGH THE EVENING. ACTIVITY MAY PERSIST INTO PARTS OF SCNTRL/SERN KY AND TN THROUGH 12Z. UPSTREAM...SYNOPTIC FRONT HAS BECOME QUITE FRAGMENTED OWING TO OUTFLOW BOUNDARIES EMANATING FROM ONGOING/OVERNIGHT MCS/S. FURTHERMORE...THE AIR MASS HAS BEEN CONVECTIVELY STABILIZED OVER AS THE 18Z ILX RAOB SUGGESTS. BUOYANCY IS GREATER FARTHER W ACROSS PARTS OF NWRN MO/NERN KS WHERE MID-LEVEL LAPSE RATES WERE STEEP AND LOW-LEVEL HEATING STRONGEST. THERE COULD BE SOME RECOVERY FROM HERE E INTO THE MIDWEST/MID-MS VLY OVERNIGHT... PRIMARILY ALOFT. SHORT TERM MODELS HAVE SUGGESTED ADDITIONAL TSTM CLUSTERS FORMING OVERNIGHT IN THIS AREA...BUT UNCERTAINTY EXISTS IN THIS SOLUTION. THERE DOES APPEAR TO BE A SUBTLE MID-LEVEL WAVE MOVING EWD THROUGH NEB ATTM...AND THIS COULD BE THE IMPETUS FOR INCREASING STORMS OVERNIGHT ACROSS PARTS OF SRN IA...NRN MO AND CNTRL IL. WILL MAINTAIN LOW SEVERE PROBABILITIES OVER THE CNTRL PLAINS...BUT MAINTAIN A SLIGHT RISK ACROSS THE MIDWEST IN WAKE OF THE MCS TO ACCOUNT FOR THIS POSSIBLE SCENARIO. ...NRN HIGH PLAINS... STRONG SFC HEATING HAS TAKEN PLACE OVER NWRN/NCNTRL NEB AND SD THIS AFTN...CONTRIBUTING TO MLCAPE 2000-3000 J/KG. MESOANALYSIS PLACES A CONVECTIVELY ENHANCED FRONT NW-SE FROM CURRENT CONVECTION OVER SWRN ND TO ERN SD AND A LEE-TROUGH SWD ACROSS WRN SD AND THE NEB PNHDL. TSTMS WILL LIKELY DEVELOP ALONG THE LEE-TROUGH SWD FROM THE BLACK HILLS LATER THIS AFTN...WITH OTHER STORMS EVOLVING ALONG SRN END OF THE SWRN ND MCS...AIDED BY A WEAK MID-LEVEL TROUGH. OTHER STORMS COULD DEVELOP FROM NCNTRL-ERN SD ALONG THE SYNOPTIC FRONT. DEEP LAYER VERTICAL SHEAR OF 30-40 KTS WILL BE SUFFICIENT FOR SUPERCELLS...WHICH WOULD LOCALLY ENHANCE THE THREAT FOR LARGE HAIL. FARTHER E...SHORT-LIVED TSTMS HAVE DEVELOPED IN THE RED RVR VLY...ALONG THE LEADING EDGE OF A BACKDOOR COLD FRONT. VERTICAL SHEAR ACROSS THIS AREA WAS WEAK AND STORMS WILL MAINLY BE OF MULTICELL VARIETY WITH PERHAPS AN ISOLD DAMAGING WIND GUST. ...NRN INTERMOUNTAIN WEST... BANDS OF TSTMS WILL CONTINUE TO DEVELOP FROM CNTRL/ERN ORE INTO ERN WA THIS AFTERNOON...ALONG LEADING EDGE OF COOLER MARINE PUSH. ISOLD DAMAGING WIND GUSTS/HAIL MAY OCCUR. ...SWRN DESERTS... HIGH PRECIPITABLE WATER VALUES AND WEAK WIND FIELDS SUGGEST THAT ANY TSTM THAT DEVELOPS WILL BE SLOW MOVING AND MAINLY A HEAVY RAINFALL THREAT. BUT...GIVEN STEEP LOW-LEVEL LAPSE RATES...ISOLD DAMAGING WET MICROBURSTS WILL BE POSSIBLE. ...NERN STATES... STRONG TSTMS HAVE EVOLVED ALONG THE LEE-TROUGH FROM SERN NY SWD INTO THE DELAWARE VLY. WEAK WIND FIELDS WILL PRECLUDE ORGANIZED STORMS...BUT STEEP LOW-LEVEL LAPSE RATES MAY CONTRIBUTE TO DOWNDRAFT ACCELERATION/ISOLD DAMAGING WINDS. ..RACY.. 08/10/2006 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z