Dec 4, 2012 1630 UTC Day 1 Convective Outlook
Updated: Tue Dec 4 16:15:33 UTC 2012
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20121204 1630 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20121204 1630 UTC Day 1 Tornado Probabilities 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
20121204 1630 UTC Day 1 Damaging Wind Probabilities 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
20121204 1630 UTC Day 1 Large Hail Probabilities 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 041611
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1011 AM CST TUE DEC 04 2012
   
   VALID 041630Z - 051200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MIDDLE TX COAST INTO
   PARTS OF DEEP S TX...
   
   ...SYNOPSIS...
   
   THE PRIMARY FEATURE OF INTEREST THIS PERIOD IS A LOW-LATITUDE
   SHORTWAVE TROUGH WHICH WILL TRANSLATE SEWD FROM THE OZARK PLATEAU
   AND SRN PLAINS INTO THE LOWER MS VALLEY AND NRN GULF OF MEXICO. 
   EMBEDDED WITHIN THIS BROADER-SCALE FEATURE...A VORTICITY MAXIMUM
   OVER ERN OK AS OF MID MORNING WILL WEAKEN TODAY IN RESPONSE TO THE
   SEWD PROGRESSION AND AMPLIFICATION OF A SECONDARY VORTICITY MAXIMUM
   AND ASSOCIATED MIDLEVEL JET STREAK FROM WRN TX INTO THE NWRN GULF OF
   MEXICO.  MEANWHILE...AN ACCOMPANYING SURFACE COLD FRONT ANALYZED
   FROM NEAR THE CONFLUENCE OF THE MS AND OH RIVERS SWWD INTO THE TX
   HILL COUNTRY AS OF 15Z WILL CONTINUE SEWD TOWARD THE TX COAST AND
   INTO THE LOWER MS VALLEY...SERVING AS THE FOCUS FOR TSTM
   DEVELOPMENT.
   
   ...MIDDLE TX COAST INTO DEEP S TX THIS AFTERNOON AND EVENING...
   
   12Z REGIONAL SOUNDINGS SHOWED THE PRESENCE OF A MOIST AIR MASS /I.E.
   LOWEST 100-MB MEAN-MIXING RATIOS OF 12-14 G PER KG/ BENEATH MODESTLY
   STEEP MIDLEVEL LAPSE RATES OF AROUND 7 C/KM.  WHEN COMBINED WITH
   LOCAL CLOUD BREAKS...THE POTENTIAL WILL EXIST FOR CORRIDORS OF
   MODERATE AFTERNOON INSTABILITY WITH MLCAPE VALUES APPROACHING
   1000-2000 J/KG.  LOW-LEVEL UPLIFT ALONG THE COLD FRONT AND
   DEVELOPING SEA-BREEZE WILL COMBINE WITH INCREASING HEIGHT FALLS/DCVA
   ATTENDANT TO W TX VORTICITY MAXIMUM TO FOSTER WIDELY SCATTERED TO
   SCATTERED TSTMS BY MID/LATE AFTERNOON.  THE SEWD PROGRESSION OF THE
   MIDLEVEL JET STREAK ATTENDING THE VORTICITY MAXIMUM WILL LEAD TO A
   CORRESPONDING INCREASE IN VERTICAL SHEAR WITH THE KINEMATIC
   ENVIRONMENT BECOMING SUPPORTIVE OF SUPERCELLS AND ORGANIZED LINE
   SEGMENTS WITH AN ASSOCIATED RISK FOR DAMAGING WINDS AND LARGE HAIL
   THROUGH THIS EVENING.
   
   ...LOWER MS VALLEY THIS AFTERNOON AND EVENING...
   
   CONSISTENT WITH CURRENT RADAR OBSERVATIONS...LATEST MODEL GUIDANCE
   SUGGESTS A GENERAL INCREASE IN TSTM COVERAGE TODAY BOTH ALONG THE
   SYNOPTIC COLD FRONT AS WELL AS WITHIN THE OPEN WARM SECTOR WHERE
   LOW-LEVEL CONFLUENCE IS ENHANCED.  WHILE THE THERMODYNAMIC
   ENVIRONMENT WILL BE COMPARABLE TO THAT ACROSS TX /I.E. MLCAPE OF
   1000-2000 J PER KG/...VERTICAL SHEAR WILL BE NOTABLY WEAKER.  THIS
   WILL RESULT IN LESS ORGANIZED AND OUTFLOW-DOMINANT STORMS CAPABLE OF
   LOCALLY STRONG WIND GUSTS AND PERHAPS SOME HAIL.
   
   ..MEAD/GARNER.. 12/04/2012
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z