Dec 20, 2014 1300 UTC Day 1 Convective Outlook
Updated: Sat Dec 20 12:49:11 UTC 2014 (20141220 1300Z Day 1 shapefile | 20141220 1300Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20141220 1300 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Tornado Graphic
20141220 1300 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.
Day 1 Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Damaging Wind Graphic
20141220 1300 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.
Day 1 Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Large Hail Graphic
20141220 1300 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.
Day 1 Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
   SPC AC 201249

   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0649 AM CST SAT DEC 20 2014

   VALID 201300Z - 211200Z

   ...NO TSTM AREAS FORECAST...

   ...SUMMARY...
   NO THUNDERSTORMS ARE EXPECTED OVER THE CONTINENTAL U.S. TODAY.

   ...SYNOPSIS...
   PROGRESSIVE UPPER-AIR PATTERN IS FCST TO CONTINUE ACROSS CONUS THIS
   PERIOD.  BY 12Z...PHASING/MERGER OF SEVERAL SMALL SHORTWAVE TROUGHS
   NOW OVER WRN CONUS WILL CONTRIBUTE TO HEIGHT FALLS ACROSS GREAT
   PLAINS STATES...WITH DEVELOPMENT OF TROUGHING AND RELATED CYCLONIC
   FLOW OVER DAKOTAS...CENTRAL PLAINS...TX AND MUCH OF NRN/WRN MEX. 
   INITIAL SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE-CHANNEL IMAGERY
   FROM OH TO AL -- IS EXPECTED TO MOVE ENEWD THROUGH TODAY.  SRN
   PORTION WILL MOVE OFFSHORE ATLC COAST AND WEAKEN FURTHER...WHILE NRN
   PORTION IS ABSORBED INTO SMALL 500-MB LOW NOW OVER W-CENTRAL NY.

   AT SFC...FRONTAL-WAVE LOW NOW OVER N-CENTRAL GULF...S OF LA
   COAST...SHOULD MOVE EWD ALONG FRONT AND WEAKEN AS UPPER SUPPORT
   MOVES AWAY.  THIS WILL LEAD TO DECELERATION AND EVENTUAL FRONTOLYSIS
   OF BAROCLINIC ZONE NOW EXTENDING SWWD FROM LOW ACROSS W-CENTRAL
   GULF. ANOTHER WEAK FRONTAL-WAVE LOW INITIALLY OFFSHORE NERN FL WILL
   MOVE ENEWD OVER ATLC SE OF SC AND S OF OUTER BANKS.  WHILE
   ASSOCIATED/ELEVATED WAA REGIME N OF LOW MAY SUPPORT SOME
   CONVECTION...THUNDER POTENTIAL THEREWITH APPEARS MINIMAL AND WELL
   OFFSHORE THROUGH PERIOD.  AIR MASS APPEARS TOO DRY AND/OR STABLE FOR
   TSTMS OVER CONUS.

   ..EDWARDS/COHEN.. 12/20/2014

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z