Dec 18, 2011 1630 UTC Day 1 Convective Outlook
Updated: Sun Dec 18 15:56:11 UTC 2011
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20111218 1630 UTC Day 1 Outlook Graphic
Probabilistic Tornado Graphic
20111218 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
20111218 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
20111218 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 181552
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0952 AM CST SUN DEC 18 2011
   
   VALID 181630Z - 191200Z
   
   ...NO SVR TSTM AREAS FORECAST...
   
   ...SYNOPSIS...
   
   UPPER LOW OVER NRN BAJA WILL ACCELERATE EWD ACROSS NWRN MEXICO AND
   SRN PARTS OF AZ/NM IN RESPONSE TO THE APPROACH OF AN UPSTREAM SYSTEM
   DIGGING SEWD THROUGH THE PACIFIC NW AND NRN INTERMOUNTAIN REGION
   INTO GREAT BASIN.  IN THE LOW LEVELS...A COLD FRONT WILL STRENGTHEN
   FROM THE UPPER GREAT LAKES INTO THE SRN HIGH PLAINS WHILE A SURFACE
   LOW DEEPENS OVER ERN NM INTO WRN TX.
   
   ...LOWER CO VALLEY INTO WRN TX/SWRN OK...
   
   THE PRIMARY FOCUS FOR TSTMS THIS PERIOD WILL BE THE CORRIDOR OF
   DCVA/HEIGHT FALLS PRECEDING UPPER LOW.  THOUGH THE AMBIENT AIR MASS
   IS NOT OVERLY MOIST /PER 12Z SOUNDINGS AND GPS PW DATA/...THE
   FORCING FOR ASCENT WILL COINCIDE WITH THE WRN EDGE OF STEEPER
   MIDLEVEL LAPSE RATES...CONTRIBUTING TO WEAK CONVECTIVE INSTABILITY. 
   ADDITIONAL ISOLATED TO WIDELY SCATTERED TSTMS WILL BE POSSIBLE WELL
   DOWNSTREAM OF UPPER SYSTEM TODAY OVER WRN TX WHERE STRENGTHENING
   LOW-LEVEL WAA WILL ALIGN WITH THE STEEP LAPSE RATES AND WRN EXTENT
   OF A MODIFIED CP AIR MASS RETURNING FROM THE NWRN GULF OF MEXICO. 
   NO SEVERE WEATHER IS EXPECTED.
   
   ..MEAD.. 12/18/2011
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z