Dec 16, 2011 0600 UTC Day 1 Convective Outlook
Updated: Fri Dec 16 05:44:09 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20111216 1200 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20111216 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
20111216 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
20111216 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 160540
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1140 PM CST THU DEC 15 2011
   
   VALID 161200Z - 171200Z
   
   ...NO TSTM AREAS FORECAST...
   
   ...SYNOPSIS...
   THE MID-LEVEL PATTERN ACROSS THE CONUS WILL GRADUALLY TRANSITION
   FROM AN INITIALLY SPLIT-FLOW REGIME TO A PREDOMINANT NRN STREAM.
   THIS WILL OCCUR AS A SHORTWAVE TROUGH QUICKLY SHIFTS ENEWD ACROSS
   WRN TX AND OK BEFORE BECOMING ABSORBED INTO A LARGER-SCALE TROUGH
   OVER THE ERN STATES. AN ASSOCIATED SFC COLD FRONT WILL SLOWLY MOVE
   SEWD ACROSS PORTIONS OF THE SERN CONUS...WHILE A WEAK FRONTAL WAVE
   SHIFTS ENEWD ALONG THE FRONT OVER THE CAROLINAS. MEANWHILE...A
   MID-LEVEL RIDGE OVER THE ERN PACIFIC WILL PENETRATE THE NWRN CONUS
   WHILE A DEEP-LAYER LOW CUTS OFF AND MEANDERS ACROSS PARTS OF FAR SRN
   CA...NRN BAJA CA...AND THE ADJACENT PACIFIC WATERS.
   
   ...TN VALLEY...
   AT LEAST MODEST MID-LEVEL ASCENT LEADING THE AFOREMENTIONED
   SHORTWAVE TROUGH WILL COMBINE WITH VERY LIMITED ELEVATED INSTABILITY
   TO SUPPORT A BROAD AREA OF SHOWERS TO THE NW OF THE SFC FRONT.
   FORECAST SOUNDINGS SUGGEST THAT THE ELEVATED BUOYANCY THAT COINCIDES
   WITH THE ASCENT WILL BE MEAGER -- I.E. MUCAPE VALUES GENERALLY LESS
   THAN 100 J/KG -- AND SUPPORT NOTHING MORE THAN VERY ISOLATED
   LIGHTNING STRIKES...AT MOST. AS SUCH...THUNDERSTORM ACTIVITY
   CURRENTLY UPSTREAM OVER NERN TX IS EXPECTED TO DECREASE IN COVERAGE
   AS THE ASCENT BECOMES INCREASINGLY REMOVED FROM GREATER INSTABILITY
   CLOSER TO THE GULF COAST. ACCORDINGLY...IT APPEARS THAT THE COVERAGE
   OF THUNDERSTORMS WILL BE SUFFICIENTLY LIMITED AFTER 12Z FRI TO
   PRECLUDE A GENERAL THUNDER AREA...AS ANY APPRECIABLE BUOYANCY WILL
   RESIDE TO THE SOUTH OF THE SPATIALLY COMPACT REGION OF FORCED ASCENT
   IN ASSOCIATION WITH THE DEAMPLIFYING MID-LEVEL WAVE.
   
   ...SRN CA AND SRN AZ...
   IN ASSOCIATION WITH THE PREVIOUSLY MENTIONED DEEP-LAYER LOW CUTTING
   OFF...500-MB TEMPERATURES AROUND -25C WILL SUPPORT 700-500-MB LAPSE
   RATES OF 7-7.5 C/KM. DESPITE THESE RELATIVELY STEEP LAPSE
   RATES...TRAJECTORIES AROUND THE ERN/NRN SEMICIRCLES OF THE LOW WILL
   NOT SUPPORT SUFFICIENT LOW/MID-LEVEL MOISTURE FOR ANY APPRECIABLE
   BUOYANCY. WHILE NAM FORECAST SOUNDINGS SUGGEST MARGINAL
   DESTABILIZATION DURING PEAK HEATING...MOST OTHER GUIDANCE SUGGESTS
   THAT DRY AIR IN THE LOW/MID LEVELS AND NEAR-ZERO CAPE WILL KEEP
   THUNDER PROBABILITIES BELOW 10 PERCENT.
   
   ..COHEN/EDWARDS.. 12/16/2011
   
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