| Sep 6, 2012 0100 UTC Day 1 Convective Outlook | |
| Updated: Thu Sep 6 01:01:32 UTC 2012 | |
| Probabilistic to Categorical Outlook Conversion Table | |
| Categorical Graphic |
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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. |
| 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. |
| 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. |
SPC AC 060057 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0757 PM CDT WED SEP 05 2012 VALID 060100Z - 061200Z ...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS SRN HIGH PLAINS TO WRN OK... ...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS MID-SOUTH/TN VALLEY REGION... ...SYNOPSIS... UPPER-AIR PATTERN IS CHARACTERIZED GENERALLY BY BROADLY CYCLONIC FLOW FROM PAC NW TO GREAT LAKES...ASSOCIATED WITH MAJOR VORTEX CENTERED IN NERN MB. STG/EMBEDDED SHORTWAVE TROUGH WAS EVIDENT IN MOISTURE CHANNEL IMAGERY OVER SERN BC AND PORTIONS WA....MOVING SEWD ACROSS NRN ROCKIES...AND SLATED TO REACH NWRN MT BEFORE END OF PERIOD. FARTHER E...TROUGH AND EMBEDDED VORTICITY MAX WERE EVIDENT OVER LS AND ADJOINING ONT LAKEHEAD REGION...NEARLY IN PHASE WITH ANOTHER PERTURBATION FROM SRN LOWER MI SWD ACROSS INDIANA TO CENTRAL KY. LATTER FEATURE SHOULD MOVE EWD TOWARD CENTRAL APPALACHIANS AND WEAKEN SOMEWHAT...WHILE LS TROUGH EJECTS ENEWD OVER NERN ONT. SEPARATE/CUT-OFF CYCLONE WAS EVIDENT OFFSHORE ATLC COAST OF CENTRAL FL. THIS FEATURE SHOULD DRIFT ERRATICALLY THROUGH 12Z...WHILE ANOTHER MID-UPPER LEVEL VORTICITY MAX AND WEAK LOW MOVES SLOWLY SWD FROM COASTAL WATERS OF EXTREME SERN LA. AT SFC...23Z CHART SHOWED WEAK LOW BETWEEN CHI-MKE...WITH COLD FRONT SWWD ACROSS SERN CORNER OF IA...MKC AREA...AND NRN TX PANHANDLE. BY 12Z...FRONT SHOULD MOVE TO LE...NRN INDIANA...MO OZARKS...WRN OK AND TX SOUTH-PLAINS REGION. SWRN PART OF THIS BOUNDARY MAY BE VERY DIFFUSE/ILL-DEFINED WITHIN REMAINS OF OUTFLOW FROM TSTMS NOW OVER SRN HIGH PLAINS. ...SRN HIGH PLAINS TO WRN OK... SCATTERED-NUMEROUS MULTICELLULAR TSTMS OVER THIS REGION ARE EXPECTED TO CONTINUE POSING RISK FOR STG-SVR OUTFLOW GUSTS FOR ANOTHER FEW HOURS INTO WHAT IS LEFT OF WELL-MIXED BOUNDARY LAYER. POTENTIAL EXISTS AMIDST GENERALLY WEAK DEEP-LAYER SHEAR AND FAVORABLE BUT DIMINISHING BUOYANCY. REF SPC WWS 622-623 AND RELATED MESOSCALE DISCUSSIONS FOR NEAR-TERM GUIDANCE. LATE THIS EVENING...COMBINATION OF DIABATIC SFC COOLING AND EXPANSIVE OUTFLOW COVERAGE WILL RENDER AIR MASS PROGRESSIVELY LESS UNSTABLE...AND DIMINISH POTENTIAL FOR DAMAGING DOWNDRAFTS TO REACH SFC. ...MID-SOUTH/TN VALLEY REGION... BAND OF STG-SVR TSTMS SHOULD CONTINUE TO MOVE SEWD ACROSS MUCH OF SERN KY...TN...AND INTO PORTIONS NRN MS/AL...WITH SPORADIC DAMAGING GUSTS THAT GENERALLY WILL BE BELOW 50-KT SVR LIMITS. REF SPC WW 621 AND ACCOMPANYING MESOSCALE DISCUSSIONS FOR NOWCAST INFORMATION ON THIS SITUATION. OVERALL SVR POTENTIAL AND CONVECTIVE ORGANIZATION EACH IS EXPECTED TO DIMINISH WITH SEWD EXTENT THROUGH ABOUT 06Z AS CONVECTION MOVES INTO REGIME CHARACTERIZED BY WEAKENING OF BOTH AMBIENT SHEAR AND INSTABILITY. ...UPPER GREAT LAKES... PROBABILITY FOR SFC-BASED SVR CONVECTION WILL CONTINUE TO DIMINISH WITH TIME AS COLD FRONT ENCOUNTERS AIR MASS STABILIZED BOTH BY SFC COOLING AND BY EARLIER MCS NOW OVER TN. ELEVATED LOW-LEVEL WAA MAY SUPPORT DEVELOPMENT OF SCATTERED TO WIDELY SCATTERED TSTMS E OR SE OF PRESENT SFC LOW POSITION...WITH MAIN CONCERN BEING ISOLATED SVR HAIL OR STG-/DAMAGING GUSTS...AS ALSO IS TRUE FOR CONVECTION NOW MOVING EWD FROM NRN LOWER MI. ..EDWARDS.. 09/06/2012 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z