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| Probabilistic Tornado Graphic | |||||||||
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| Probability of a tornado within 25 miles of a point. Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point. |
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| Probabilistic Damaging Wind Graphic | |||||||||
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| Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point. |
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| Probabilistic Large Hail Graphic | |||||||||
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| Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point. |
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SPC AC 091629 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1129 AM CDT FRI AUG 09 2013 VALID 091630Z - 101200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE DELMARVA INTO SERN PA AND NJ... ...DELMARVA INTO SERN PA/NJ... VISIBLE IMAGERY SHOWS LIMITED CLOUDS FROM SRN/ERN VA INTO THE DELMARVA PENINSULA...WITH BREAKS IN CLOUDS NWD INTO NJ. STRONGER DIABATIC HEATING HAS OCCURRED AHEAD OF AN ADVANCING CLOUD SHIELD WITH SURFACE TEMPERATURES RANGING FROM NEAR 90 IN VA TO LOW 80S IN NJ. DESPITE MODEST LAPSE RATES...AMPLE MOISTURE /DEW POINTS IN LOW/MID 70S AND PW AOA 2 IN/ IS CONTRIBUTING TO CAPE VALUES AROUND 1500 J/KG...AND WEAK CIN SHOULD RESULT IN CONVECTION INITIATION OCCURRING DURING EARLY/MID AFTERNOON HOURS CONSISTENT WITH CONSENSUS OF MULTIPLE CONVECTION-ALLOWING MODEL FORECASTS. 12Z AREA SOUNDINGS AND LATEST VAD WIND PROFILES INDICATE 30-40 KT OF WLY FLOW ABOVE 1-2 KM AGL WHICH WILL SUPPORT PRIMARILY ORGANIZED MULTICELL CONVECTIVE STRUCTURES. AS STORMS MOVE EWD DURING THE AFTERNOON AND EARLY EVENING HOURS...DOWNWARD TRANSFER OF HORIZONTAL MOMENTUM AUGMENTED BY PRECIPITATION-LOADING EFFECTS SHOULD SUPPORT DEVELOPMENT OF A FEW WET MICROBURSTS CAPABLE OF PRODUCING LOCALIZED DAMAGING WIND GUSTS. ...PARTS OF NEW ENGLAND... AN EXTENSIVE AREA OF CLOUDS AND PRECIPITATION MOVING ACROSS THIS REGION IS INHIBITING STRONGER DIURNAL HEATING AND DESTABILIZATION. WIND PROFILES EXHIBIT STRONGER LOW LEVEL FLOW THAT VEERS WITH HEIGHT WITH RESULTANT VERTICAL SHEAR THAT IS FAVORABLE FOR ORGANIZED CONVECTIVE STRUCTURES INCLUDING POSSIBLE SUPERCELLS. HOWEVER...THE WIDESPREAD PRECIPITATION IS LIKELY TO LIMIT OVERALL SEVERE POTENTIAL ALTHOUGH AN EMBEDDED STORM OR TWO MAY BE CAPABLE OF PRODUCING MARGINAL SEVERE WIND OR A BRIEF TORNADO DURING THE AFTERNOON. ...ERN OK TO WRN KY/TN... A CONVECTIVELY-ENHANCED MID LEVEL TROUGH OVER NRN OK IS FORECAST TO DRIFT ENEWD TO THE SE KS/SW MO BORDER REGION BY TONIGHT. A WEAK COLD FRONT IS EXPECTED TO BEGIN MOVING SWD FROM KY/MO TO TN/AR...MODIFIED BY ONGOING CONVECTION. WEAK CONVERGENCE ALONG THE FRONT WILL SUPPORT ADDITIONAL THUNDERSTORM DEVELOPMENT THIS AFTERNOON AS THE MOIST BOUNDARY LAYER HEATS ALONG AND S OF THE EFFECTIVE FRONT. MODERATE INSTABILITY IS EXPECTED ALONG THE FRONT/DIFFERENTIAL HEATING ZONE...AND VERTICAL SHEAR WILL BE MORE FAVORABLE FOR ORGANIZED STORM CLUSTERS IN THE WEAK NELY FLOW ON THE IMMEDIATE COOL SIDE OF THE FRONT. A FEW DAMAGING GUSTS WILL BE POSSIBLE FROM ERN OK ACROSS NRN AR TO WRN TN...WHERE THE STRONGER INSTABILITY COINCIDES WITH A BELT OF SOMEWHAT ENHANCED MID LEVEL FLOW ON THE IMMEDIATE SE SIDE OF THE WEAK MID LEVEL TROUGH. ...ERN NM AREA... A DEPARTING MID LEVEL TROUGH OVER THE PLAINS WILL LEAVE LITTLE LARGE-SCALE FOCUS FOR ASCENT ACROSS THIS AREA. STILL...LINGERING LOW-LEVEL MOISTURE AS A WEAK UPSLOPE FLOW REGIME DEVELOPS THIS AFTERNOON SHOULD SUPPORT AT LEAST WIDELY SCATTERED THUNDERSTORM DEVELOPMENT ALONG THE E SLOPES OF THE HIGHER TERRAIN. STORMS SHOULD SUBSEQUENTLY MOVE SLOWLY SEWD THROUGH THE EVENING...WITH SOME POTENTIAL FOR ISOLATED LARGE HAIL AND STRONG GUSTS GIVEN MLCAPE OF 1000-1500 J/KG AND EFFECTIVE BULK SHEAR OF 25-30 KT. ...SE MT/NE WY/SW SD... PATTERN OF WEAK LOW-LEVEL FRONTOGENESIS IS EXPECTED TO PERSIST ALONG FROM NERN WY ACROSS SWRN SD AND ADDITIONAL THUNDERSTORM DEVELOPMENT IS EXPECTED THIS AFTERNOON. RESIDUAL LOW-LEVEL MOISTURE BENEATH THE NE EDGE OF THE STEEPER MIDLEVEL LAPSE RATES WILL CONTRIBUTE TO WEAK-MODERATE INSTABILITY...WHILE DEEP-LAYER VERTICAL SHEAR WILL BE AT LEAST MARGINALLY FAVORABLE FOR ORGANIZED MULTICELLS AND/OR SUPERCELLS. ISOLATED LARGE HAIL AND DAMAGING GUSTS WILL BE THE MAIN THREATS FOR A FEW HOURS THIS AFTERNOON/EVENING. ...NRN CA TO CENTRAL ORE THIS AFTERNOON/EVENING... SUFFICIENT DEEP LAYER MOISTURE AND ASCENT NE OF THE QUASI-STATIONARY UPPER LOW OVER THE NRN CA COAST IS SUPPORTING THUNDERSTORMS OVER NERN CA ATTM...AND ADDITIONAL CONVECTION IS LIKELY TO SPREAD/DEVELOP INTO PARTS OF OREGON THIS AFTERNOON/EVENING. MODEST INSTABILITY AND DEEP-LAYER SELY SHEAR WILL SUPPORT A FEW ORGANIZED CLUSTERS CAPABLE OF PRODUCING ISOLATED STRONG/DAMAGING GUSTS AND MARGINALLY SEVERE HAIL. ..WEISS/BUNTING.. 08/09/2013 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z |