Categorical Graphic
Probabilistic Tornado 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
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
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 211616
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1116 AM CDT TUE AUG 21 2012
   
   VALID 211630Z - 221200Z
   
   ...NO SVR TSTM AREAS FORECAST...
   
   ...SYNOPSIS...
   
   WRN U.S. RIDGE WILL BE SUPPRESSED THIS PERIOD AS A SHORTWAVE TROUGH
   MOVES FROM THE PACIFIC NW COAST THROUGH THE NRN INTERMOUNTAIN
   REGION.  E OF THE ROCKIES...BROAD TROUGHING WILL BE MAINTAINED WITH
   THE MOST PROMINENT FEATURE BEING AN EMBEDDED VORTICITY MAXIMUM WHICH
   WILL TRANSLATE FROM THE MIDWEST INTO CNTRL APPALACHIANS.  IN THE LOW
   LEVELS...A WEAK SURFACE FRONT WILL MOVE SLOWLY EWD ACROSS THE
   PIEDMONT AND COASTAL PLAINS...AND SWD TOWARD THE GULF COAST. 
   ELSEWHERE...A QUASI-STATIONARY BOUNDARY WILL PERSIST FROM THE NRN
   HIGH PLAINS INTO MID AND LOWER MO VALLEY.  
   
   ...NRN INTERMOUNTAIN REGION THIS AFTERNOON AND EVENING...
   
   LARGE-SCALE FORCING FOR ASCENT WILL STRENGTHEN TODAY AHEAD OF
   ABOVE-MENTIONED SHORTWAVE TROUGH...GIVING RISE TO A GRADUAL INCREASE
   IN TSTM ACTIVITY.  WHILE 12Z REGIONAL SOUNDINGS SHOWED THE PRESENCE
   OF STEEP MIDLEVEL LAPSE RATES...MOISTURE WAS SOMEWHAT LIMITED WITH
   PW VALUES OF 0.7-0.8 INCH WHICH SHOULD MODULATE THE DEGREE OF AIR
   MASS DESTABILIZATION AND OVERALL SEVERE POTENTIAL. 
   NONETHELESS...THE STEEP LAPSE RATES COUPLED WITH 40-45 KT OF DEEP
   SWLY SHEAR MAY PROMOTE ISOLATED SEVERE STORMS CAPABLE OF HAIL AND
   LOCALLY DAMAGING WIND GUSTS THROUGH THIS EVENING.
   
   ...ERN CAROLINAS INTO FL THIS AFTERNOON AND EVENING...
   
   VORTICITY MAXIMUM OVER THE FL PNHDL/SRN AL/SWRN GA WILL WEAKEN TODAY
   WHILE PROGRESSING INTO AN INCREASINGLY CONFLUENT MIDLEVEL FLOW
   REGIME ALONG THE ATLANTIC COAST.  FORCING ASSOCIATED WITH THIS
   FEATURE WILL AUGMENT LOW-LEVEL UPLIFT ALONG SURFACE SYNOPTIC FRONT
   AND PRE-EXISTING STORM-SCALE OUTFLOW BOUNDARIES TO FOSTER AN
   INCREASE IN TSTMS THROUGH THE PEAK OF THE DIURNAL HEATING CYCLE. 
   BOTH LAPSE RATES AND VERTICAL SHEAR WILL REMAIN MODEST...THOUGH THE
   VERY MOIST ENVIRONMENT WILL CONTRIBUTE TO POCKETS OF MODERATE
   INSTABILITY /I.E. MLCAPE OF 1000-2000 J PER KG/ AND THE POTENTIAL
   FOR LOOSELY ORGANIZED STORM CLUSTERS CAPABLE OF MAINLY LOCALLY
   DAMAGING WIND GUSTS.
   
   FOR ADDITIONAL NEAR-TERM GUIDANCE ON N FL...SEE MCD 1796. 
   
   ...AZ/LOWER CO VALLEY THIS AFTERNOON AND EVENING...
   
   SATELLITE-DERIVED PW IMAGERY AND 12Z SOUNDINGS REVEALED THE PRESENCE
   OF A SEASONABLY MOIST ENVIRONMENT WITHIN A WEAK TROPOSPHERIC FLOW
   REGIME COINCIDENT WITH MIDLEVEL RIDGE.  EXPECT TSTMS TO FORM ALONG
   THE HIGH TERRAIN THIS AFTERNOON BEFORE SUBSEQUENTLY
   MOVING/PROPAGATING WWD/SWWD ONTO THE DESERT FLOOR. 
   ISOLATED...SEVERE WIND GUSTS WILL BE POSSIBLE...ESPECIALLY WITH ANY
   SUSTAINED TSTM CLUSTERS THAT CAN EVOLVE.
   
   ..MEAD/SMITH.. 08/21/2012
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z