Dec 14, 2011 0600 UTC Day 1 Convective Outlook
Updated: Wed Dec 14 06:02:12 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20111214 1200 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20111214 1200 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
20111214 1200 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
20111214 1200 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 140558
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1158 PM CST TUE DEC 13 2011
   
   VALID 141200Z - 151200Z
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM CENTRAL/NERN TX INTO FAR
   SERN OK...
   
   ...SYNOPSIS...
   SWRN U.S. UPPER TROUGH...CURRENTLY MOVING EWD THROUGH SRN AZ PER
   WATER VAPOR IMAGERY...WILL BE FORCED TO EJECT THROUGH THE CENTRAL
   PLAINS TO THE GREAT LAKES REGION THIS FORECAST PERIOD...AS AN
   UPSTREAM NERN PACIFIC SHORTWAVE TROUGH DIGS SEWD TOWARD THE PACIFIC
   NWRN STATES.  IN THE LOW LEVELS...A SURFACE LOW WILL TRACK
   CONCURRENTLY WITH THE EJECTING SWRN U.S. TROUGH AND ALONG A
   BAROCLINIC ZONE EXTENDING ENEWD FROM KS...WITH THE SURFACE LOW
   REACHING THE GREAT LAKES BY 12Z THURSDAY.  A SWD EXTENDING
   BOUNDARY/DRY LINE TYPE FEATURE FROM WRN KS/OK INTO NWRN-W TX AT 12Z
   TODAY WILL BE THE PRIMARY FEATURE FOR SURFACE BASED TSTMS TO BE
   FOCUSED ALONG AND E OF FOR THE SLIGHT RISK TODAY.  FARTHER N...
   ELEVATED CONVECTION ALSO WILL BE GENERALLY LOCATED ALONG AND E OF
   THIS SAME BOUNDARY AND THROUGH THE WARM SECTOR EXTENDING ACROSS THE
   MID MS TO OH VALLEYS.  
   
   ...CENTRAL/NERN TX TO SRN/SERN OK...
   THE LEAD SWRN U.S. TROUGH WILL TRANSLATE DOWNSTREAM IN A
   POSITIVE-TILT FASHION ULTIMATELY LIMITING LOW LEVEL CONVERGENCE
   ALONG ADVANCING WIND SHIFT/FRONT.  MIDLEVEL LAPSE RATES WILL BE
   SUFFICIENTLY STEEP TO SUPPORT ELEVATED ONGOING THUNDERSTORMS AT THE
   START OF DAY 1 ACROSS PORTIONS OF KS/OK INTO NWRN TX.  A FEW OF
   THESE STORMS MAY EVEN BE SURFACE BASED...WITH MUCAPE UP TO 800-1000
   J/KG ADEQUATE FOR HAIL APPROACHING SEVERE LEVELS.  
   
   A STRONG LLJ EARLY IN THE PERIOD WILL PROVE FAVORABLY LOCATED FOR
   BOUNDARY LAYER MOISTURE RETURN ACROSS TX WHICH WILL ALLOW SURFACE
   DEWPOINTS TO RISE THROUGH THE 60S ACROSS THE WARM SECTOR PRIOR TO
   FRONTAL PASSAGE...SUPPORTING SURFACE BASED DEVELOPMENT.  LOW LEVEL
   CONVERGENCE IS EXPECTED TO BE STRONGEST ACROSS NWRN INTO NORTH
   CENTRAL TX THIS MORNING...BEFORE WANING AS THE LLJ AND STRONGER
   FORCING SHIFT INTO THE MID MS/OH VALLEYS REGION.  HOWEVER...EVEN
   SOME BOUNDARY LAYER HEATING AND WEAK FRONTAL CONVERGENCE SHOULD
   ENHANCE THE POTENTIAL FOR SURFACE BASED CONVECTION...LIKELY
   INITIATING JUST WEST OF THE I-35 CORRIDOR WHEN TEMPERATURES WARM
   INTO THE UPPER 60S.  CONFIDENCE REMAINS SUFFICIENT FOR THIS SCENARIO
   SUCH THAT A SLIGHT RISK EXTENDS FROM CENTRAL/NERN TX INCLUDING THE
   DALLAS-FORT WORTH METRO AREA INTO FAR SERN OK.  DEEP LAYER SHEAR
   WILL SUPPORT A FEW SUPERCELLS ALONG THE ADVANCING FRONT.  ALL FACETS
   OF SEVERE WEATHER WILL BE POSSIBLE INCLUDING AN ISOLATED TORNADO. 
   
   ...NORTH OF THE SLIGHT RISK AREA...
   BOUNDARY LAYER SHOULD NOT MODIFY MUCH PRIOR TO THE FRONTAL
   PASSAGE...AND THUS ACTIVITY WITH NNEWD EXTENT WILL REMAIN ELEVATED
   WITH SOME THREAT FOR SMALL HAIL.
   
   ..PETERS/HURLBUT.. 12/14/2011
   
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