Jul 8, 2011 2000 UTC Day 1 Convective Outlook | |
Updated: Fri Jul 8 19:50:10 UTC 2011 | |
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 081945 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0245 PM CDT FRI JUL 08 2011 VALID 082000Z - 091200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE NRN ROCKIES/PLAINS SWD INTO CENTRAL HIGH PLAINS...... ...THERE IS A SLGT RISK OF SVR TSTMS FROM SRN NEW ENGLAND ACROSS THE MID ATLANTIC STATES AND INTO THE MIDDLE TN VALLEY... ...NRN ROCKIES... STORMS HAVE RECENTLY DEVELOPED NEAR COLD FRONT OVER PORTIONS OF NERN ID/SWRN MT WITHIN AN ENVIRONMENT CHARACTERIZED BY MUCAPES BETWEEN 1000-2000 J/KG AND DEEP LAYER SHEAR AT 30-35 KT. THUS... HAVE EXTENDED SLIGHT RISK WWD TO ACCOUNT FOR THESE STORMS SLOWLY INTENSIFYING THROUGH THE AFTERNOON...WITH ISOLATED SEVERE HAIL/WINDS EXPECTED. ...NRN AZ... HAVE INCREASED LOW PROBS FOR MARGINALLY SEVERE HAIL AND WINDS WITH STORMS THAT HAVE DEVELOPED NORTH OF THE RIM. ALTHOUGH THE TROPOSPHERIC WINDS ARE GENERALLY WEAK...MLCAPES AROUND 1000 J/KG AND STEEP MID/HIGH LEVEL LAPSE RATES WILL RESULT IN A FEW STORMS PRODUCING BRIEF HAIL AND/OR WINDS. ...WRN TN VALLEY... ALTHOUGH MOST STORM SCALE AND OPERATIONAL MODELS INDICATE THAT CONVECTION MAY DEVELOP ALONG THE FRONT...VISIBLE SATELLITE SUGGESTS SUBSIDENCE IS STRONGER THAN FORECAST BEHIND UPPER IMPULSE CURRENTLY STRETCHING FROM OH SWWD INTO MIDDLE TN/NRN MS. ALTHOUGH MORE HEATING MAY AID IN A STRONG STORM OR TWO TO DEVELOP...LOWERED SEVERE PROBABILITIES GIVEN THE SUBSIDENCE AS WELL AS WEAKENING CONVERGENCE ALONG WEAK FRONTAL BOUNDARY. ELSEWHERE...FORECAST ON TRACK WITH ONLY MINOR LINE CHANGES TO ACCOUNT FOR CURRENT TRENDS. ..IMY.. 07/08/2011 .PREV DISCUSSION... /ISSUED 1117 AM CDT FRI JUL 08 2011/ ...NRN PLAINS INTO CENTRAL HIGH PLAINS... UPPER LOW OVER BC/ALTA WILL CONTINUE MOVING EWD THROUGH TONIGHT...WHILE SOUTHEAST OF THE LOW A SHORT WAVE TROUGH EVIDENT IN WATER VAPOR IMAGERY CROSSING CENTRAL MT WILL MOVE EWD INTO THE NRN PLAINS. LARGE SCALE ASCENT ASSOCIATED WITH THE SHORT WAVE TROUGH IS GENERATING CLOUDS AND SCATTERED CONVECTION OVER ERN MT/ND/WRN SD ATTM...WHICH MAY LIMIT MAGNITUDE OF DIABATIC HEATING/DESTABILIZATION OVER SOME AREAS THIS AFTERNOON. HOWEVER...SUFFICIENTLY STEEP LAPSE RATES COUPLED WITH AMPLE LOW LEVEL MOISTURE /SURFACE DEW POINTS IN MID-UPPER 60S FROM PARTS OF THE DAKOTAS AND ERN MT/ WILL CONTRIBUTE TO DEVELOPMENT OF MLCAPE OF 1000-2000 J/KG LATER THIS AFTERNOON. STORMS ARE EXPECTED TO SLOWLY INCREASE IN INTENSITY THIS AFTERNOON AS THE SHORT WAVE TROUGH AND ASSOCIATED SURFACE COLD FRONT NOW MOVING INTO CENTRAL MT SHIFT EWD ACROSS ERN MT TOWARD THE DAKOTAS. WIND PROFILES ARE EXPECTED TO EXHIBIT CONSIDERABLE VEERING WITH HEIGHT SUPPORTIVE OF A FEW SUPERCELLS CAPABLE OF PRODUCING VERY LARGE HAIL AND STRONG WIND GUSTS. A FEW TORNADOES MAY ALSO BE POSSIBLE...ESPECIALLY ALONG AND NORTH OF THE RETREATING WARM FRONT OVER PARTS OF THE DAKOTAS. STORMS ARE LIKELY TO CONSOLIDATE INTO ONE OR TWO MCS/S THIS EVENING AS THE LOW LEVEL JET INTENSIFIES AFTER 00-03Z...WITH INCREASING WIND DAMAGE POTENTIAL ALONG THE LEADING EDGE OF THE CONVECTIVE OUTFLOW. A SEPARATE AREA OF STORMS MAY ALSO DEVELOP OVER PARTS OF SOUTH CENTRAL/SERN MT NEAR THE COLD FRONT AS IT MOVES ACROSS THE REGION. STEEPER MID LEVEL LAPSE RATES...SUFFICIENT MOISTURE...AND FAVORABLE DEEP LAYER SHEAR INDICATE POTENTIAL FOR A FEW HIGHER-BASED SEVERE STORMS CAPABLE OF PRODUCING HAIL AND DAMAGING WIND GUSTS. FARTHER SOUTH...STORMS ARE LIKELY TO DEVELOP BY MID/LATE AFTERNOON FROM WRN NEB INTO ERN CO WITHIN THE EXISTING LOW LEVEL MOISTURE/INSTABILITY AXIS WHERE STRONG HEATING WILL INCREASE MLCAPE TO 1500-2000 J/KG. THE SRN EDGE OF STRONGER WESTERLY WINDS ALOFT WILL EXTEND ACROSS THIS REGION PROVIDING STRONG DEEP LAYER VERTICAL SHEAR SUPPORTIVE OF SEVERE STORMS INCLUDING A FEW SUPERCELLS. LARGE HAIL AND STRONG WIND GUSTS WILL BE THE PRIMARY THREATS DURING THE LATE AFTERNOON AND EVENING. ...SRN NEW ENGLAND ACROSS THE MID ATLANTIC STATES INTO THE TN VALLEY... WATER VAPOR IMAGERY SHOWS A WELL-DEFINED SHORT WAVE TROUGH FROM THE MID OHIO VALLEY SWWD INTO THE MID-SOUTH...WITH AN EXTENSIVE BAND OF CLOUDS AND EMBEDDED CONVECTION IN ADVANCE OF THE TROUGH. CLOUD COVER THINS ALONG/EAST OF THE LEADING EDGE OF THE BAND FROM SRN NEW ENGLAND ACROSS THE DELMARVA ACROSS THE CENTRAL APPALACHIANS AND TN WHERE STRONGER DIABATIC HEATING AND DESTABILIZATION ARE OCCURRING. IMMEDIATELY SOUTH/EAST OF THE UPPER TROUGH...A BAND OF STRONGER WSWLY MID LEVEL WINDS IS PRESENT FROM THE CENTRAL APPALACHIANS ACROSS THE MID ATLANTIC STATES...AND RESULTANT EFFECTIVE VERTICAL SHEAR OF 30-45 KT WILL ENHANCE STORM ORGANIZATION THIS AFTERNOON AND EVENING. MULTIPLE CLUSTERS OF THUNDERSTORMS ARE EXPECTED TO GRADUALLY INTENSIFY THIS AFTERNOON...ESPECIALLY ALONG/AHEAD OF THE LEADING EDGE OF THE CURRENT CLOUDS/CONVECTION...WITH STRONGER STORMS CAPABLE OF PRODUCING DAMAGING WIND GUSTS AND HAIL. CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z