Feb 29, 2012 0830 UTC Day 3 Severe Thunderstorm Outlook
Updated: Wed Feb 29 08:26:03 UTC 2012
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20120229 0830 UTC Day 3 Outlook Graphic
Probabilistic Graphic
20120229 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 290823
   
   DAY 3 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0223 AM CST WED FEB 29 2012
   
   VALID 021200Z - 031200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS OH VALLEY STATES TO
   CENTRAL/SRN APPALACHIANS AND LOWER MS RIVER REGION...
   
   ...SYNOPSIS...
   WRN-CONUS SYNOPTIC-SCALE TROUGHING DESCRIBED IN DAY-2 OUTLOOK IS
   FCST TO PROGRESS EWD ACROSS CENTRAL CONUS DAY-3.  BY 3/00Z...TROUGH
   SHOULD EXHIBIT STG POSITIVE TILT...EXTENDING FROM MID-UPPER LOW OVER
   MN/ONT BORDER REGION SWWD ACROSS CENTRAL PLAINS TO BASAL SHORTWAVE
   TROUGH OVER NRN NM.  NEAR END OF PERIOD...CONSENSUS OF
   OPERATIONAL/SREF GUIDANCE REASONABLY POSITIONS TROUGHING ALOFT FROM
   N OF LH SWWD ACROSS PORTIONS IA/MO/OK TO SRN NM/FAR W TX REGION.
   
   AT SFC...2/12Z CYCLONE SHOULD BE POSITIONED INVOF SWRN MO...AS
   FRONTAL WAVE PERTURBED BY WEAK/LEADING MIDLEVEL SHORTWAVE.  SFC LOW
   IS EXPECTED TO MOVE NEWD AND DEEPEN THROUGHOUT DAYLIGHT
   HOURS...REACHING NWRN INDIANA/WRN LOWER MI AREA BY 3/00Z.  AT THAT
   TIME...COLD FRONT SHOULD EXTEND SWWD ACROSS INDIANA...AR...AND
   CENTRAL TX...WITH WARM FRONT SEWD INTO CENTRAL APPALACHIANS.  THIS
   WARM FRONT WILL BE SEPARATE FROM DAY-2 VERSION OVER SRN PLAINS/LOWER
   MS VALLEY REGION...THAT WILL HAVE DISSIPATED BY EARLY DAY-3.  BY
   3/12Z...COLD FRONT SHOULD REACH WRN NY...CENTRAL/SRN
   APALACHIANS...CENTRAL/SRN MS AND UPPER TX COAST.
   
   ...MS/GA/AL TO OH VALLEY STATES...
   GROUPS OF TSTMS MAY CARRY OVER FROM DAY-2 PERIOD OVER PORTIONS
   MID-MS VALLEY TO MID-SOUTH REGIONS...MOVING NEWD TOWARD OH VALLEY
   STATES.  WHILE THIS ACTIVITY MAY BE ELEVATED INITIALLY...COMBINATION
   OF DIABATIC HEATING AND STG BOUNDARY-LAYER THETAE ADVECTION SHOULD
   DESTABILIZE FOREGOING AIR MASS ENOUGH TO YIELD SFC-BASED EFFECTIVE
   INFLOW PARCELS.  STG DEEP-LAYER SPEED SHEAR AND MID-UPPER WIND
   SPEEDS INDICATE FAST STORM MOTIONS ARE LIKELY...POTENTIALLY AOA 50
   KT...WITH DAMAGING GUSTS COMPRISING BULK OF SVR EVENTS...AND
   TORNADOES ALSO POSSIBLE.
   
   ANOTHER AREA OF TSTMS WITH WIND DAMAGE/TORNADO POTENTIAL SHOULD
   DEVELOP ALONG/AHEAD OF SFC COLD FRONT FROM LATE AFTERNOON INTO
   OVERNIGHT HOURS...OVER PORTIONS KY/TN/MS...IN FAVORABLE
   BOUNDARY-LAYER MOISTURE.  THIS ACTIVITY EVENTUALLY SHOULD EVOLVE TO
   QUASI-LINEAR GIVEN NEARLY PARALLEL NATURE OF MEAN FLOW WITH RESPECT
   TO ZONE OF LOW-LEVEL ASCENT.  HOWEVER...VERY STG LOW-LEVEL AND
   DEEP-LAYER SHEAR...ESPECIALLY DURING EVENING OVER PORTIONS KY/TN AND
   NRN MS/NWRN AL...INDICATE FIRST FEW HOURS OF CONVECTIVE REGIME MAY
   INVOLVE FAST-MOVING/SFC-BASED SUPERCELLS AND ACCORDINGLY ENHANCED
   TORNADO POTENTIAL.  EXTENT TO WHICH THIS REGIME WILL LINK WITH
   EARLIER/OH VALLEY CONVECTION IS UNCERTAIN...AS ARE IMPORTANT MODE
   CONSIDERATIONS SUCH AS PACE OF LINEAR EVOLUTION.  UNCERTAINTY
   REGARDING HOW FAR SW BACKBUILDING WILL OCCUR...INTO PROGRESSIVELY
   STRONGER CAPPING AND WEAKER LOW-LEVEL CONVERGENCE...IS MANIFEST AS
   DECREASING UNCONDITIONAL PROBABILITIES OVER LA AND E TX.
   
   ..EDWARDS.. 02/29/2012
   
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   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0830Z