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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 171645 DAY 1 CONVECTIVE OUTLOOK CORR 1 NWS STORM PREDICTION CENTER NORMAN OK 1145 AM CDT FRI MAY 17 2013 VALID 171630Z - 181200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM NERN WY INTO WRN/CENTRAL SD... ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF MS AND AL... ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF CENTRAL TX... CORRECTED TORNADO POINTS PRODUCT ...NERN WY INTO WRN/CENTRAL SD... FULL-LATITUDE UPPER TROUGH HAS MOVED ONSHORE ALONG THE PACIFIC COAST AND IS FORECAST TO PROGRESS EWD THROUGH TONIGHT REACHING THE INTERMOUNTAIN REGION BY THE END OF THE PERIOD. SOUTHERLY LOW LEVEL FLOW OVER THE PLAINS IS EXPECTED TO INCREASE IN RESPONSE TO THE APPROACHING UPPER TROUGH...WITH NWD MOISTURE TRANSPORT CONTINUING INTO THE NRN PLAINS. AT THE SURFACE...A LOW CURRENTLY OVER SERN WY WILL MOVE SLOWLY NEWD TOWARD SWRN SD AS A WARM FRONT EXTENDING EWD ACROSS SRN SD EDGES NWD. DEW POINTS ARE FORECAST TO REMAIN IN THE 50S EAST OF A DRY LINE OVER THE HIGH PLAINS...WITH LOWER 60S POSSIBLE INTO PARTS OF SD...AND STRONG DIABATIC HEATING WILL RESULT IN DEVELOPMENT OF A DEEP WELL-MIXED BOUNDARY WITH CAPE REACHING 1000-1500 J/KG. ALTHOUGH DYNAMIC FORCING FOR LARGE SCALE ASCENT WILL BE MINIMAL...HEATING OVER ELEVATED TERRAIN COMBINED WITH OROGRAPHIC LIFT AND LOW LEVEL CONVERGENCE NEAR THE SURFACE LOW/WARM FRONT IS EXPECTED TO SUPPORT CONVECTION INITIATION FROM PARTS OF NERN WY INTO WRN SD DURING THE MID/LATE AFTERNOON HOURS. DEEP LAYER SHEAR WILL BE ENHANCED AS STRONGER SWLY WINDS ALOFT /40-45 KT AT 500 MB/ OVERSPREAD THE REGION. THIS WILL SUPPORT POTENTIAL FOR HIGH-BASED SUPERCELLS TO DEVELOP AND SPREAD ENEWD DURING THE LATE AFTERNOON AND EVENING HOURS. AS THE LOW LEVEL JET STRENGTHENS AFTER SUNSET...ACTIVITY MAY GROW UPSCALE INTO SEVERAL CLUSTERS/SMALL MCS/S AND CONTINUE EWD DURING THE OVERNIGHT HOURS. A THREAT FOR PRIMARILY HAIL MAY ACCOMPANY THESE STORMS. ...MS/AL... UPPER LOW OVER THE MID-SOUTH IS EXPECTED TO CONTINUE SLOWLY WEAKENING AS IT MOVES EWD. EXTENSIVE CLOUD COVER IS ASSOCIATED WITH THE LOW ACROSS MS AND NRN AL WHICH IS LIKELY TO INHIBIT HEATING THIS AFTERNOON. FARTHER SOUTH...VISIBLE IMAGERY SUGGESTS PRESENCE OF SEVERAL LOW LEVEL BOUNDARIES EXTENDING FROM WEST-CENTRAL AL WSWWD ACROSS CENTRAL AND SRN MS WITH SOME BREAKS IN THE CLOUDS NOTED. 12Z RAOBS AT JAN AND LIX SUGGEST THAT DIABATIC HEATING MAY BE SUFFICIENT TO WEAKEN THE CAP AND PERMIT STORMS TO DEVELOP LATER THIS AFTERNOON AND EVENING WITHIN THE SRN SEMICIRCLE OF THE UPPER LOW. ALTHOUGH THERE ARE SOME DIFFERENCES IN MODEL PRECIPITATION/CONVECTIVE STORM FORECASTS ACROSS THIS AREA...THERE IS POTENTIAL FOR STORMS TO DEVELOP AND FAVORABLE CAPE/SHEAR ENVIRONMENT SUGGEST POSSIBILITY OF A FEW SEVERE STORMS TO OCCUR. ...TX... THE SURFACE DRYLINE IS FORECAST TO EXTEND ACROSS WEST-CENTRAL TX LATER THIS AFTERNOON. CONSENSUS OF MODEL GUIDANCE CONTINUES TO INDICATE ISOLATED CONVECTION INITIATION ALONG THE DRYLINE LATE THIS AFTERNOON AND EARLY EVENING. FORECAST SOUNDINGS IN THIS AREA SHOW MLCAPE VALUES OF 2500-3500 J/KG WITH SUFFICIENT CAPPING TO LIMIT THE NUMBER OF STORMS THAT CAN FORM. NEVERTHELESS...THERE WILL LIKELY BE A NARROW ZONE ALONG THE DRYLINE WHERE A COMBINATION OF STRONG HEATING AND DEEP MIXING CAN ELIMINATE THE CAP AND ALLOW A STORM OR TWO. SUPERCELLS CAPABLE OF LARGE HAIL AND DAMAGING WINDS ARE THE MAIN THREATS. ..WEISS.. 05/17/2013 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z |