Apr 13, 2011 0730 UTC Day 3 Severe Thunderstorm Outlook
Updated: Wed Apr 13 07:30:58 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20110413 0730 UTC Day 3 Outlook Graphic
Probabilistic Graphic
20110413 0730 UTC Day Probabilitic Graphic
Probability Legend Image
   SPC AC 130728
   
   DAY 3 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0228 AM CDT WED APR 13 2011
   
   VALID 151200Z - 161200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE LOWER TO
   MID-MS VALLEY...CNTRL GULF COAST...TN VALLEY AND OH VALLEY...
   
   ...LOWER TO MID-MS VALLEY/CNTRL GULF COAST/TN VALLEY/OH VALLEY...
   A STRONG NEGATIVELY-TILED UPPER-LEVEL LOW IS FORECAST TO MOVE FROM
   THE CNTRL PLAINS EWD INTO THE OZARKS ON FRIDAY. THE EXIT REGION OF A
   WELL-DEVELOPED 80 TO 100 KT MID-LEVEL JET IS FORECAST TO SPREAD
   ACROSS THE CNTRL GULF COAST STATES DURING THE DAY CREATING STRONG
   DEEP LAYER SHEAR PROFILES FAVORABLE FOR SEVERE STORMS. THE
   GFS...ECMWF AND NAM BEGIN THE DAY 3 PERIOD WITH AN MCS LOCATED IN
   THE MID-MS VALLEY DRIVING THIS FEATURE EWD INTO WRN KY AND WRN TN BY
   MIDDAY. SOUTH ACROSS THE WARM SECTOR...THE MODELS DEVELOP MODERATE
   INSTABILITY ACROSS MUCH OF THE CNTRL GULF COAST STATES AND INITIATE
   NUMEROUS THUNDERSTORMS FROM MIDDLE TN SWWD INTO NCNTRL AL...MS AND
   SE LA DURING THE AFTERNOON. THE DEVELOPMENT OF A SEVERE MCS SEEMS
   PROBABLE ACROSS THE CNTRL AND SRN PARTS OF THE SLIGHT RISK AREA
   FRIDAY AFTERNOON AND EVENING.
   
   FORECAST SOUNDINGS IN CNTRL MS AND WRN AL AT 21Z ON FRIDAY SHOW
   IMPRESSIVE WIND SHEAR PROFILES WITH 50 TO 60 KT OF 0-6 KM SHEAR AND
   0-3 KM STORM RELATIVE HELICITIES AROUND 400 M2/S2. THIS ENVIRONMENT
   SHOULD SUPPORT SUPERCELL DEVELOPMENT WITH A THREAT FOR STRONG
   TORNADOES POSSIBLE. HOWEVER...THE MAGNITUDE OF THE TORNADO THREAT
   WILL BE CONDITIONAL UPON STORM MODE. IF A SQUALL-LINE WERE TO
   DEVELOP INSTEAD OF MORE DISCRETE CONVECTION....THEN WIND DAMAGE
   COULD BE THE GREATER THREAT. THE UPPER-LEVEL SYSTEM IS QUITE
   IMPRESSIVE WITH A WELL-DEVELOPED LOW-LEVEL JET IN PLACE ACROSS THE
   ECNTRL STATES. THE GFS AND NAM SOLUTIONS FOCUS THE LOW-LEVEL JET
   FURTHER NORTH IN TN AND KY BY LATE AFTERNOON WHILE THE ECMWF SHOWS A
   STRONG COMPONENT OF THE JET IN THE TN VALLEY AND CNTRL GULF COAST
   STATES. IF THE ECMWF SOLUTION IS CORRECT AND MOISTURE RETURN ENDS UP
   BEING STRONGER THAN FORECAST...THEN A TORNADO OUTBREAK COULD OCCUR
   IN PARTS OF WRN TO MIDDLE TN...MS AND AL FRIDAY AFTERNOON. AT THIS
   POINT...THE POTENTIAL FOR AN OUTBREAK REMAINS CONDITIONAL AND
   DIFFERENCES IN THE MODEL SOLUTIONS RAISE UNCERTAINTIES CONCERNING
   THE EXACT SCENARIO.
   
   FURTHER NORTH ACROSS THE OH VALLEY...SEVERE STORMS WILL ALSO BE
   POSSIBLE FRIDAY AFTERNOON AS THE UPPER-LEVEL LOW APPROACHES FROM THE
   WEST. IN SPITE OF WEAKER INSTABILITY...A STRONG WIND FIELD IS
   FORECAST WITH COLD TEMPS ALOFT. THIS WOULD RESULT IN A POTENTIAL FOR
   HAIL AND WIND DAMAGE WITH THE MORE ORGANIZED CONVECTIVE CLUSTERS. A
   TORNADO THREAT WILL ALSO BE POSSIBLE IN THE OH VALLEY DUE TO THE
   STRONG LOW-LEVEL SHEAR FORECAST BUT THIS POTENTIAL SHOULD BE
   DEPENDENT UPON MOISTURE RETURN.
   
   ..BROYLES.. 04/13/2011
   
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   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z