Aug 23, 2017 0730 UTC Day 3 Severe Thunderstorm Outlook
Updated: Wed Aug 23 15:39:23 UTC 2017 (20170823 0730Z Day 3 shapefile | 20170823 0730Z Day 3 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
0730 UTC Day 3 Outlook Graphic
Day 3 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MARGINAL 22,236 6,042,792 Houston, TX...Corpus Christi, TX...Pasadena, TX...Sugar Land, TX...Missouri City, TX...
Probabilistic Graphic
20170823 0730 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
5 % 22,238 6,042,792 Houston, TX...Corpus Christi, TX...Pasadena, TX...Sugar Land, TX...Missouri City, TX...
   SPC AC 231539

   Day 3 Convective Outlook AMEND 1
   NWS Storm Prediction Center Norman OK
   1039 AM CDT Wed Aug 23 2017

   Valid 251200Z - 261200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
   THE TEXAS COAST AND VICINITY...

   AMENDED FOR ADDITION OF A MARGINAL AREA FOR PORTIONS OF THE TEXAS
   COAST AND VICINITY

   ...SUMMARY...
   The risk for a few tornadoes and severe-thunderstorm wind gusts may
   affect the Texas Coast on Friday and especially Friday night, in
   association with Tropical Cyclone Harvey.

   ...Day 3 Convective Outlook Amendment...
   The circulation in the Bay of Campeche has regenerated into Tropical
   Depression Harvey, and the National Hurricane Center has
   re-initiated advisories on this system. The latest NHC advisory
   specifies that Harvey is forecast to approach the coast of Texas
   late Friday. On its forecast track, the northeast quadrant of this
   system (and nearby portions of adjacent quadrants) -- i.e.,
   associated with some tornado and severe-thunderstorm wind 
   potential -- will affect portions of the Texas Coast and vicinity
   throughout the Day-3/Friday period. This should especially be the
   case Friday night, as convective elements and low-topped
   mini-supercells with feeder bands move onshore. Given the recent
   regeneration of Harvey, with the issuance of a Hurricane Watch for
   portions of the Texas Coast, the Day 3 Convective Outlook has been
   updated to add a Marginal area for portions of the Texas Coast and
   vicinity to account for tornado and severe-thunderstorm wind
   potential. Adjustments to this area, along with the potential for
   Slight Risk delineation, may become necessary in subsequent
   outlooks, as the system continues to evolve and more precise details
   are ascertained regarding the exact corridor of increased
   buoyancy/shear parameter-space favoring tornado potential.

   Otherwise, the forecast for sub-5-percent severe probabilities
   across the remainder of the contiguous United States remains
   unchanged.

   ..Cohen/Bunting.. 08/23/2017

   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z