Aug 24, 2015 1300 UTC Day 1 Convective Outlook
Updated: Mon Aug 24 12:52:53 UTC 2015 (20150824 1300Z Day 1 shapefile | 20150824 1300Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20150824 1300 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Tornado Graphic
20150824 1300 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.
Day 1 Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Damaging Wind Graphic
20150824 1300 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.
Day 1 Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Large Hail Graphic
20150824 1300 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.
Day 1 Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
   SPC AC 241252

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0752 AM CDT MON AUG 24 2015

   VALID 241300Z - 251200Z

   ...NO SVR TSTM AREAS FORECAST...

   ...SUMMARY...
   SEVERAL AREAS OF THUNDERSTORMS ARE POSSIBLE TODAY IN A BROAD ARC
   FROM THE NORTHEASTERN U.S. THROUGH THE SOUTHEAST...THEN ACROSS THE
   GULF COAST STATES TO PARTS OF THE DESERT SOUTHWEST AND ROCKY
   MOUNTAIN STATES.  A FEW THUNDERSTORMS WITH GUSTY WINDS ALSO MAY
   AFFECT PARTS OF THE INTERIOR NORTHWEST.

   ...SYNOPSIS...
   CONUS PORTION OF LARGE-SCALE/UPPER-AIR PATTERN WILL FEATURE
   1. RIDGING OVER ROCKIES...ACCOMPANYING STRENGTHENING ANTICYCLONE
   OVER 4 CORNERS...AND
   2. ERN TROUGHING...ANCHORED BY PRONOUNCED CYCLONE NOW CENTERED OVER
   ONT NEAR NRN LAKEHEAD REGION OF LS.  AS SEVERAL MESOSCALE VORTICITY
   MAXIMA PIVOT AROUND THAT VORTEX...NET CENTROID SHOULD SHIFT ESEWD
   ACROSS NRN ONT TO JUST N OF LH BY END OF PERIOD.  ASSOCIATED
   TROUGHING BY THEN WILL EXTEND SWD ACROSS OH AND SRN
   APPALACHIANS...PHASING AT LEAST LOOSELY WITH ANTECEDENT WEAKNESS IN
   500-MB HEIGHT FIELD OVER ERN GULF AND NWRN CARIBBEAN.

   AT SFC...COLD FRONT RELATED TO ONT CYCLONE WAS ANALYZED AT 11Z FROM
   SRN ONT ACROSS WRN PA...WV...ERN TN...SRN AR...THROUGH WEAK
   FRONTAL-WAVE LOW NEAR DFW METROPLEX...TO LOWER PECOS VALLEY AREA. BY
   00Z BOUNDARY SHOULD MOVE TO ERN NY..CENTRAL MD...WRN CAROLINAS...SRN
   AL...AND SW TX...LOSING DEFINITION FARTHER W ACROSS W TX AND ERN NM.
    BY 12Z...DECELERATING FRONT SHOULD REACH WRN NEW ENGLAND...LOWER
   CHESAPEAKE/TIDEWATER AREA...SRN GA AND MS RIVER MOUTH.

   ...NERN CONUS...
   NARROW BAND OF CONVECTION...INCLUDING WIDELY SCATTERED
   TSTMS...SHOULD DEVELOP TODAY FROM CENTRAL NY TO NRN/CENTRAL VA. 
   ACTIVITY SHOULD FORM INVOF SFC COLD FRONT AS IT IMPINGES UPON
   CORRIDOR OF DIABATICALLY DESTABILIZED AIR AND LOW-LEVEL MOIST
   ADVECTION/TRANSPORT.  FRONTAL CONVERGENCE AND WILL BE LIMITED BY
   LACK OF MORE SUBSTANTIAL NEAR-SFC WINDS...AS WILL LOW-LEVEL SHEAR. 
   HOWEVER...GIVEN WEAK CINH...SUFFICIENT LIFT SHOULD EXIST FOR GRADUAL
   CONVECTIVE DEVELOPMENT FROM MIDDAY THROUGH LATE AFTN...WITH NET NEWD
   MOTION OF CELLS AND EWD SHIFT OF CONVECTIVE BAND TOWARD ERN NY...ERN
   PA AND CENTRAL MD.  ACTIVITY SHOULD DISSIPATE AS IT SHIFTS CLOSER TO
   MID ATLC COAST AND NEW ENGLAND THIS EVENING...WITH SFC DIABATIC
   COOLING STRIPPING AWAY BUOYANCY BY THE HOUR. 
   PREFRONTAL/FRONT-PARALLEL PLUME OF 500-1200 J/KG MLCAPE MAY DEVELOP
   BY MID AFTN WITH SFC DEW POINTS RANGING FROM MID-UPPER 50S F UNDER
   COOLER AIR ALOFT ON N END...TO MID/UPPER 60S OVER SOME PARTS OF VA. 
   HOWEVER...RELATIVE DRY POCKET NOTED IN MORNING SFC ANALYSIS OVER
   PORTIONS ERN VA MAY ADVECT NWD INTO SOME PREFRONTAL INFLOW PARCELS
   AND REDUCE CAPE.

   WHILE AN ISOLATED STG GUST CANNOT BE RULED OUT FROM MOST
   SUSTAINED/INTENSE CELLS...KEY FACTORS PRECLUDE ADDITION OF
   MRGL-UNCONDITIONAL SVR AREA ATTM...
   1. WEAK MEAN LAPSE RATES IN LOW-MIDDLE LEVELS...AS EVIDENT IN 12Z
   PIT/BUF/ALB RAOBS THAT SAMPLED WARM NOSES ALOFT.  WARMTH ALOFT MAY
   MODERATE SLIGHTLY AMIDST GRADUAL HEIGHT FALLS AHEAD OF ONT
   CYCLONE...BUT APPRECIABLE DCVA/COOLING ALOFT REMAINS BEHIND SFC
   FRONT IN PROGS.
   2. WEAK LOW-MIDDLE LEVEL FLOW...LIMITING NOT ONLY LOW-LEVEL
   CONVERGENCE/SHEAR BUT DEEP SHEAR ALSO.  MOST FCST SOUNDINGS SHOW
   EFFECTIVE-SHEAR MAGNITUDES BELOW 30 KT.

   ...NWRN CONUS...
   ISOLATED TSTMS SHOULD DEVELOP TODAY OVER CORRIDOR FROM NWRN CA TO
   SERN WA...INITIALLY OVER DIABATICALLY HEATED HIGHER TERRAIN...THEN
   SPREADING/MOVING OVER DEEP/WELL-MIXED BOUNDARY LAYERS EXHIBITING
   INVERTED-V CHARACTERISTICS ON FCST SOUNDINGS.  PW AROUND .75 INCH
   AND 100-400 J/KG MLCAPE MAY LOFT SUFFICIENT UPDRAFT-WATER MASS TO
   YIELD A FEW STG DOWNDRAFT GUSTS...ESPECIALLY WHEN FACTORING IN
   POTENTIAL FOR MOMENTUM TRANSFER IN RELATIVELY FAST-MOVING CELLS. 
   ATTM LACK OF MORE ROBUST BUOYANCY AND NEBULOUS MID/UPPER-LEVEL
   SUPPORT PRECLUDE UNCONDITIONAL SVR PROBABILITIES.  RELATED DRY-TSTM
   FIRE HAZARD ALSO EXISTS ACROSS THIS AREA...REF SPC OUTLOOK FOR
   RELATED DETAILS ON FIRE WEATHER.

   ..EDWARDS/COOK.. 08/24/2015

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