Dec 9, 2016 0830 UTC Day 3 Severe Thunderstorm Outlook
Updated: Fri Dec 9 08:38:35 UTC 2016 (20161209 0830Z Day 3 shapefile | 20161209 0830Z Day 3 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
0830 UTC Day 3 Outlook Graphic
Day 3 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Graphic
20161209 0830 UTC Day Probabilitic Graphic
Probability of severe weather within 25 miles of a point.
Hatched Area: 10% or greater probability of significant severe within 25 miles of a point.
Day 3 Prob. Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
No Risk Areas Forecast
   SPC AC 090838

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0238 AM CST Fri Dec 09 2016

   Valid 111200Z - 121200Z


   Thunderstorms may occur across parts of the lower and mid
   Mississippi and Ohio Valleys Sunday.  Showers and a few/occasional
   lightning strikes may also occur over portions of the coastal
   Pacific Northwest.

   While solutions continue to differ -- both between the various
   models and also from run to run within the same model, some
   amplification of the upper flow field across the U.S. appears likely
   to occur Sunday, as short-wave troughing embedded in the
   fast/cyclonic westerlies moves quickly out of the Rockies and across
   the north-central portion of the country.  As this occurs,
   cyclogenesis is forecast as a lee low -- initially over the central
   high Plains vicinity -- moves northeastward toward the Ohio
   Valley/upper Great Lakes while deepening.  A trailing cold front is
   forecast to shift southeastward across the southern Plains and
   mid-Mississippi Valley overnight.

   ...mid and lower Mississippi/Ohio Valleys...
   While warm-sector thunderstorms appear unlikely at this time across
   the Sabine River Valley area of east Texas and western Louisiana
   during the day, isentropic ascent/warm advection atop a cool
   continental boundary layer will occur ahead of the developing
   surface low and associated frontal system on Sunday.  Moistening
   aloft is expected to result in eventual elevated destabilization
   sufficient for development of showers and scattered thunderstorms --
   from roughly the mid Mississippi to the mid Ohio Valleys.  While
   uncertainty remains regarding pattern evolution, and thus details of
   convective potential, thunder risk apparent at this time warrants
   inclusion of a 10% area, but with destabilization likely
   insufficient to support appreciable hail potential.

   ...coastal Pacific Northwest...
   Fast west-northwesterly upslope flow in the lower and middle
   troposphere combined with a pocket of cold mid-level air (-34 C at
   500 mb) spreading across the area will support showers -- and
   occasional lightning -- across coastal mountain ranges of WA and OR
   Sunday.  Lack of sufficient CAPE for robust updrafts will preclude
   any appreciable severe risk.

   ...southeast U.S. coastal areas...
   Scattered showers, and possibly a couple of thunderstorms, may occur
   across FL through the day, and could spread northward into the
   coastal Carolinas overnight.

   ..Goss.. 12/09/2016