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
20110708 2000 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20110708 2000 UTC Day 1 Tornado Probabilities Graphic
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
20110708 2000 UTC Day 1 Damaging Wind Probabilities Graphic
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
20110708 2000 UTC Day 1 Large Hail Probabilities Graphic
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.
   
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