Dec 23, 2012 0830 UTC Day 3 Severe Thunderstorm Outlook
Updated: Sun Dec 23 08:30:56 UTC 2012
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20121223 0830 UTC Day 3 Outlook Graphic
Probabilistic Graphic
20121223 0830 UTC Day Probabilitic Graphic
Probability of severe weather within 25 miles of a point.
Hatched Area: 10% or greater probability of significant severe within 25 miles of a point.
   SPC AC 230829
   
   DAY 3 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0229 AM CST SUN DEC 23 2012
   
   VALID 251200Z - 261200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
   PLAINS...LOWER MS VALLEY AND CNTRL GULF COAST STATES...
   
   ...GULF COAST STATES...
   AN IMPRESSIVE UPPER-LEVEL SYSTEM IS FORECAST TO MOVE EWD INTO THE
   SRN PLAINS EARLY TUESDAY MORNING AS THE EXIT REGION OF A POWERFUL
   MID-LEVEL JET MOVES INTO THE GULF COAST STATES. AHEAD OF THE
   SYSTEM...MOISTURE IS FORECAST TO RETURN NWD INTO THE LOWER MS VALLEY
   AND CNTRL GULF COAST STATES WITH MODERATE INSTABILITY DEVELOPING
   ACROSS THE SRN AND WRN PART OF THE SLIGHT RISK AREA EARLY IN THE DAY
   ON TUESDAY. A CLUSTER OF THUNDERSTORMS OR SQUALL-LINE MAY BE ALREADY
   DEVELOPED BY DAYBREAK ON TUESDAY ACROSS EAST TX WITH ADDITIONAL
   STORMS POSSIBLY ONGOING ACROSS THE LOWER MS VALLEY. MODEL FORECASTS
   INCREASE CONVECTIVE COVERAGE ACROSS THE LOWER MS VALLEY AND APPEAR
   TO MOVE A WELL-DEVELOPED MCS EWD ACROSS THE REGION DURING THE DAY.
   
   FORECAST SOUNDINGS AT MIDDAY TUESDAY IN THE LOWER MS VALLEY DEVELOP
   AN IMPRESSIVE SHEAR ENVIRONMENT AS THE MID-LEVEL JET APPROACHES THE
   REGION FROM THE WEST. NAM FORECAST SOUNDINGS VALID TUESDAY AT 21Z
   JUST SOUTHWEST OF JACKSON MS SHOW MLCAPE VALUES AROUND 1500 J/KG
   WITH ABOUT 60 KT OF DEEP LAYER SHEAR. THIS COMBINED WITH 0-3 KM
   STORM RELATIVE HELICITIES AROUND 400 M2/S2 COULD BE FAVORABLE FOR
   SUPERCELLS AND TORNADOES. IF MANY CELLS CAN REMAIN DISCRETE...THEN
   CONDITIONS COULD ALSO BE FAVORABLE FOR STRONG TORNADOES AS THE
   LOW-LEVEL JET MOVES EWD ACROSS THE CNTRL GULF COAST STATES FROM
   TUESDAY MORNING INTO THE AFTERNOON. AT THIS POINT...THE POTENTIAL
   FOR WIDESPREAD WIND DAMAGE APPEARS JUST AS VIABLE. THE MAGNITUDE OF
   THESE THREATS MAY DEPEND UPON THE DOMINANT STORM MODE. IF THE
   FAVORED MODE ENDS UP BEING LINEAR...THEN WIND DAMAGE COULD BE THE
   GREATER THREAT.
   
   FORECAST SOUNDINGS ACROSS THE LOWER MS VALLEY AND CNTRL GULF COAST
   STATES TUESDAY INTO TUESDAY NIGHT SHOW POTENTIAL FOR A SUBSTANTIAL
   SEVERE WEATHER EVENT. THE COMBINATION OF SHEAR AND INSTABILITY
   COMBINED WITH A POTENT WEATHER SYSTEM SUGGESTS A 30 PERCENT
   PROBABILITY AND SIGNIFICANT SEVERE HATCHED AREA ARE WARRANTED. THE
   SEVERE THREAT SHOULD CONTINUE INTO TUESDAY EVENING AND POSSIBLY INTO
   THE OVERNIGHT PERIOD AS THE UPPER-LEVEL TROUGH MOVES QUICKLY EWD
   ACROSS THE GULF COAST STATES.
   
   ..BROYLES.. 12/23/2012
   
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   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0830Z