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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 170544 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1244 AM CDT FRI MAY 17 2013 VALID 171200Z - 181200Z ...THERE IS A SLGT RISK OF SVR TSTMS FOR PORTIONS OF NRN MS/AL... ...THERE IS A SLGT RISK OF SVR TSTMS NEAR THE BLACK HILLS... ...SYNOPSIS... A MID-UPPER TROUGH SITUATED OVER THE WRN STATES WILL SLOWLY MOVE EWD WITH THE AXIS EXTENDING FROM THE ERN GREAT BASIN THROUGH THE FOUR CORNERS BY DAYBREAK SATURDAY. DOWNSTREAM OF THIS FEATURE...RISING MID LEVEL HEIGHTS WILL OCCUR OVER A SIZABLE AREA OF THE CNTRL-SRN PLAINS IN WAKE OF A WEAKENING MID LEVEL CIRCULATION OVER THE LOWER OH/TN VALLEYS. RICHER LOW LEVEL MOISTURE WILL STREAM NWD ACROSS THE PLAINS TO THE E/SE OF AN ELONGATED LEE LOW OVER THE CNTRL HIGH PLAINS WITH AN ATTENDANT DRYLINE EXTENDING INTO W TX. ...LOWER MS RIVER VALLEY... ON THE S-SIDE OF THE MID LEVEL VORTICITY MAXIMUM...PRIMARILY WLY COMPONENT TO THE MID LEVEL FLOW ACROSS TX INTO THE LOWER MS RIVER VALLEY WILL AID IN THE ERN FRINGE OF THE SRN PLAINS EML OVERSPREADING THE AREA NEAR/WEST OF THE MS RIVER IN WAKE OF EARLY DAY CONVECTION. DESPITE ONLY MODEST 20-30 KT H5 FLOW...FORECAST SOUNDINGS SHOW STRONG LOW LEVEL VEERING RESULTING IN 30-35 KT EFFECTIVE SHEAR...SUFFICIENT FOR ORGANIZED STORMS. THE STRONGEST STORMS MAY BE CAPABLE OF POCKETS OF WIND DAMAGE...AS WELL AS ISOLD LARGE HAIL AND PERHAPS A TORNADO. ...BLACK HILLS VICINITY... THE GRADUAL APPROACH OF THE UPPER TROUGH FROM THE WEST WILL ACT TO MAINTAIN INCREASINGLY MOIST SLY FLOW OVER THE N-CNTRL HIGH PLAINS TO THE E OF A SURFACE LOW LOCATED OVER ERN WY. BACKED E-NELY FLOW N OF THE BLACK HILLS WILL AID IN MAINTAINING 50S DEWPOINTS IN NERN WY/SERN MT AND ADJACENT DAKOTAS DURING THE LATE AFTERNOON. ALTHOUGH LARGE SCALE FORCING WILL REMAIN PRIMARILY WEST OF THE REGION DURING PEAK HEATING...OROGRAPHIC LIFT AND UPSLOPE FLOW WILL PROBABLY LEAD TO ISOLD STORMS BY EARLY EVENING. FORECAST SOUNDINGS SHOW UPWARDS OF 1000 J/KG MLCAPE DEVELOPING N AND W OF THE BLACK HILLS AS FLOW INCREASES FROM THE SW IN THE MID-UPPER LEVELS...SUPPORTIVE OF STORM ROTATION. ISOLD LARGE HAIL/SEVERE WIND GUSTS APPEAR TO BE THE MAIN THREATS AS STORMS DEVELOP/MOVE EWD AS THE LLJ/WAA INCREASE BY MID-LATE EVENING. ...CNTRL HIGH PLAINS... A FEW WIDELY-SPACED STORMS MAY DEVELOP BY THE LATE AFTERNOON/EARLY EVENING PERIOD ACCORDING TO SOME MODEL GUIDANCE. DESPITE CAPPING CONCERNS /10-14 DEG C AT H7 FROM NORTH TO SOUTH/...STRONG HEATING ALONG THE DRYLINE YIELDING STEEP LAPSE RATES MAY SUPPORT A LOCALIZED STRONG-SEVERE STORM THREAT CONSISTING OF ISOLD LARGE HAIL/DMGG WINDS. ..SMITH/MARSH.. 05/17/2013 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z |