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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 171940 DAY 1 CONVECTIVE OUTLOOK CORR 1 NWS STORM PREDICTION CENTER NORMAN OK 0240 PM CDT FRI MAY 17 2013 VALID 172000Z - 181200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF TX... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NRN PLAINS... ...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE CNTRL GULF STATES... CORRECTED FOR SIG HAIL LINE ...TX... HAVE OPTED TO INTRODUCE 10 PERCENT SIG HAIL THREAT TO PORTIONS OF TX AND EXPAND THE CATEGORICAL SLGT NORTH AND EAST TOWARD THE WRN PARTS OF NCNTRL TX. LATEST HIGH RES MODEL GUIDANCE HAS TRENDED TOWARD SCATTERED TSTM DEVELOPMENT ALONG THE DRYLINE FROM EAST OF SJT TO NW OF MWL OVER THE NEXT FEW HOURS. LATEST VIS IMAGERY SUPPORTS THIS EVOLUTION WITH DEEPENING CU FIELD OVER MCCULLOCH COUNTY AND NEW CU OVER SHACKELFORD COUNTY NE OF ABI. WITH SFC TEMPERATURES AROUND 103F AT BOTH ABI AND SJT...AND WITH DEW POINTS NEAR 70 EAST OF THE DRYLINE...IT APPEARS TSTMS WILL DEVELOP SHORTLY. EXTREME SBCAPE...ON THE ORDER OF 4000 J/KG...AND MODEST DEEP LAYER SHEAR SUGGEST VERY LARGE HAIL MAY ACCOMPANY THESE STORMS. ADDITIONALLY...STRONG DOWNBURSTS COULD BE OBSERVED GIVEN THE TEMP/DEW POINT SPREADS. ...ELSEWHERE... EARLIER THOUGHTS REGARDING CONVECTION NEAR THE BLACK HILLS AND OVER THE CNTRL GULF STATES REMAIN. ..DARROW.. 05/17/2013 .PREV DISCUSSION... /ISSUED 1145 AM CDT FRI MAY 17 2013/ 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. CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z |