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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 121226 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0726 AM CDT SUN MAY 12 2013 VALID 121300Z - 131200Z ...NO SVR TSTM AREAS FORECAST... ...SYNOPSIS... AN AMPLIFIED LARGE-SCALE PATTERN WILL BE MAINTAINED THROUGH THE D1 PERIOD...FEATURING A LONG-WAVE TROUGH OVER ERN PARTS OF THE U.S. AND CANADA...AND A REX BLOCK FROM WRN CANADA INTO NWRN MEXICO AND BAJA. WITHIN THIS BROAD-SCALE REGIME...A VORTICITY RIBBON SITUATED IN THE EXIT REGION OF A POLAR JET STREAK OVER THE NRN PLAINS/UPPER MS VALLEY WILL INTENSIFY WHILE TRANSLATING EQUATORWARD INTO THE LOWER MS VALLEY BY TONIGHT. THIS FEATURE WILL BE ATTENDED BY A WEAK SURFACE LOW THAT WILL DEVELOP FROM THE CNTRL HIGH PLAINS INTO NWRN OK BY 13/00Z...ALONG A NNW-SSE ORIENTED WARM FRONT THAT WILL SLOWLY SHIFT EWD ACROSS THE HIGH PLAINS. ELSEWHERE...A COLD FRONT FROM THE MID ATLANTIC COAST TO GULF COAST WILL PROGRESS SEWD INTO THE FL PENINSULA. ...FL THIS AFTERNOON AND EVENING... DAYTIME HEATING AND A MOIST...PRE-FRONTAL BOUNDARY LAYER /CHARACTERIZED BY DEWPOINTS IN THE UPPER 60S TO LOWER 70S/ WILL CONTRIBUTE TO A MODERATELY UNSTABLE AIR MASS THIS AFTERNOON WITH MLCAPE APPROACHING 1000-1500 J/KG. WHILE LARGE-SCALE FORCING WILL REMAIN NEGLIGIBLE...CONVERGENCE ALONG DEVELOPING SEA BREEZE BOUNDARIES WILL BE SUFFICIENT TO INITIATE WIDELY SCATTERED TSTMS. 12Z OBSERVED SOUNDINGS AND MODEL GUIDANCE SUGGEST THAT REGION WILL RESIDE ALONG THE SRN FRINGE OF THE STRONGER MID AND HIGH-LEVEL FLOW ATTENDANT TO THE ERN CONUS TROUGH...RESULTING IN VERTICAL SHEAR MARGINALLY SUPPORTIVE OF STORM ORGANIZATION. LOCALLY STRONG WIND GUSTS AND PERHAPS SOME HAIL WILL BE POSSIBLE INTO THIS EVENING BEFORE TSTMS BEGIN TO WEAKEN AND/OR MOVE OFFSHORE. ...NWRN OK/NERN TX PNHDL LATE THIS AFTERNOON INTO EVENING... STEEP LOW TO MIDLEVEL LAPSE RATES WILL COMPENSATE FOR A RELATIVELY DRY AIR MASS WITH SBCAPE VALUES APPROACHING 500 J/KG INVOF THE MIGRATORY SURFACE LOW AND WARM FRONT. DAYTIME HEATING COUPLED WITH LOW-LEVEL CONVERGENCE ALONG THESE FEATURES AND THE GLANCING INFLUENCE OF THE VORTICITY MAXIMUM MENTIONED ABOVE MAY BE SUFFICIENT TO INITIATE ISOLATED STORMS WITHIN A KINEMATIC ENVIRONMENT FEATURING PRONOUNCED VEERING WINDS WITH HEIGHT AND 40-45 KT OF DEEP-LAYER SHEAR. GIVEN THE RELATIVELY COOL THERMODYNAMIC PROFILES AND POTENTIAL FOR UPDRAFT ROTATION...MARGINALLY SEVERE HAIL IS POSSIBLE PRIOR TO STORM DISSIPATION LATE THIS EVENING. ..MEAD/BOTHWELL.. 05/12/2013 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z |
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