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 221930
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0130 PM CST WED FEB 22 2012
   
   VALID 222000Z - 231200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS LATE THIS AFTN AND EVE ACROSS
   PARTS OF THE TENNESSEE VALLEY AND SOUTHERN APPALACHIANS REGION...
   
   ...20Z OUTLOOK UPDATE...TN VALLEY INTO SRN APPALACHIANS...
   
   ENOUGH UNCERTAINTIES EXIST TO PRECLUDE MAKING SUBSTANTIVE CHANGES TO
   THE 1630Z OUTLOOK.  HOWEVER...GUIDANCE GENERALLY SEEMS TO INDICATE
   THE SOUTHERN TENNESSEE/ALABAMA/GEORGIA BORDER AREA AS THE MOST
   LIKELY FOCUS FOR SIGNIFICANT CONVECTIVE DEVELOPMENT THROUGH 22-00Z. 
   THIS APPEARS TO BE WHERE LOW-LEVEL WARM ADVECTION IS STRONGEST...AS
   ANOTHER AREA OF AT LEAST WEAK MID-LEVEL FORCING FOR UPWARD VERTICAL
   MOTION APPROACHES.  A GRADUAL DESTABILIZATION OF THE BOUNDARY LAYER
   IS ONGOING ACROSS THIS REGION...WITH INSOLATION AND SURFACE DEW
   POINTS RISING THROUGH THE LOWER 50S.  CAPE WILL REMAIN WEAK...BUT
   SIZABLE CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS AND STRONG MEAN
   LOWER/MID TROPOSPHERIC FLOW OF 40-50+ KT SUPPORTS AT LEAST THE RISK
   FOR POTENTIAL DAMAGING CONVECTIVELY ENHANCED GUSTS.
   
   ..KERR.. 02/22/2012
   
   .PREV DISCUSSION... /ISSUED 1026 AM CST WED FEB 22 2012/
   
   ...SYNOPSIS...
   
   A BROAD CYCLONIC MIDLEVEL FLOW REGIME WILL BE MAINTAINED ACROSS MUCH
   OF THE CONUS THROUGH THE D1 PERIOD.  SEVERAL LOW-AMPLITUDE
   PERTURBATIONS WILL PROGRESS THROUGH THIS PATTERN...ONE OF NOTE WILL
   TRANSLATE FROM THE CNTRL PLAINS INTO THE TN VALLEY BY THIS EVENING. 
   IN THE LOW LEVELS...A DIFFUSE WARM FRONT ANALYZED FROM SERN OK
   ACROSS NRN PARTS OF MS/AL/GA/SC INTO CNTRL NC MAY LIFT SLIGHTLY
   NWD...SERVING AS THE FOCUS FOR STRONG-SEVERE TSTM DEVELOPMENT THIS
   AFTERNOON AND EVENING.  FARTHER S...A SECONDARY WARM FRONT
   --DELINEATING A MODIFIED CP AIR MASS FROM THAT OF MT ORIGIN-- WILL
   LIFT NWD FROM THE SHELF WATERS ONTO THE GULF COAST.  THIS BOUNDARY
   MAY ALSO GIVE RISE TO ISOLATED STRONG TO POTENTIALLY SEVERE TSTM
   DEVELOPMENT THIS AFTERNOON AND EVENING.
   
   ...TN VALLEY/SRN APPALACHIANS...
   
   CLUSTERS OF ELEVATED TSTMS ARE ONGOING ACROSS TN...FORCED BY DCVA
   ATTENDANT TO A WEAK LEAD IMPULSE AND WAA/ISENTROPIC ASCENT OCCURRING
   TO THE N OF SURFACE WARM FRONT AT THE TERMINUS OF A 40-50 KT WSWLY
   LLJ.  ALONG AND S OF THE CURRENT TSTM ACTIVITY...FILTERED SUNSHINE
   COUPLED WITH BOUNDARY LAYER DEWPOINTS RISING THROUGH THE 50S WILL
   ALIGN WITH STEADILY COOLING MIDLEVEL TEMPERATURES TO YIELD AFTERNOON
   MLCAPE VALUES OF 500-1500 J/KG.  
   
   IN THE WAKE OF THE INITIAL TSTM ACTIVITY...THE WEAKLY FORCED NATURE
   OF THE LARGE-SCALE PATTERN IS MANIFEST IN NOTABLE VARIANCE IN MODEL
   FORECASTS OF WHEN/WHERE SURFACE-BASED TSTMS WILL DEVELOP LATER
   TODAY.  CURRENT INDICATIONS ARE THAT DIURNALLY ENHANCED TSTM
   DEVELOPMENT WILL BECOME INCREASINGLY LIKELY BY MID-LATE AFTERNOON
   INVOF WARM FRONT AS FORCING FOR ASCENT ATTENDANT TO ABOVE-MENTIONED
   UPSTREAM IMPULSE INTERACTS WITH THE DESTABILIZING BOUNDARY LAYER. 
   HERE...FORECAST SOUNDINGS SHOW LONG HODOGRAPHS WITH EFFECTIVE BULK
   SHEAR OF 50-60 KT AND EFFECTIVE SRH OF 150-250 M2/S2.  AS
   SUCH...SETUP WILL BE SUPPORTIVE OF SUPERCELLS AND BOWING STRUCTURES
   CAPABLE OF A FEW TORNADOES...DAMAGING WINDS AND HAIL.
   
   EXPECT THE SEVERE WEATHER THREAT TO DIMINISH BY LATE EVENING INTO
   TONIGHT OVER THE SRN APPALACHIANS AS THE BOUNDARY LAYER BEGINS TO
   COOL AND STABILIZE.  
   
   ...CNTRL/NERN GULF COAST...
   
   AS MENTIONED ABOVE...SRN WARM FRONT WILL LIFT NWD THROUGH THE PERIOD
   WITH BOUNDARY CURRENTLY EXTENDING FROM SRN LA ESEWD TO VICINITY OF
   DEVELOPING TSTMS OVER THE SHELF WATERS OF THE NERN GULF OF MEXICO. 
   LARGE-SCALE FORCING FOR ASCENT IS FORECAST TO REMAIN NEGLIGIBLE AND
   THE DEVELOPING TSTMS MAY SLOW THE NWD RETREAT OF THE WARM FRONT. 
   NONETHELESS...MODEL GUIDANCE DOES INDICATE AN INCREASING RISK FOR
   ISOLATED SEVERE TSTMS LATER TODAY INTO THIS EVENING AS A
   MOISTENING/DESTABILIZING BOUNDARY LAYER ALIGNS WITH A KINEMATIC
   ENVIRONMENT SIMILAR TO THAT MENTIONED IN THE PREVIOUS SECTION.  DUE
   TO UNCERTAINTIES IN STORM COVERAGE...LOW SEVERE PROBABILITIES WILL
   BE MAINTAINED.  HOWEVER...AN UPGRADE TO A CATEGORICAL SLIGHT RISK
   REMAINS POSSIBLE LATER TODAY.
   
   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z