Sep 8, 2017 0730 UTC Day 3 Severe Thunderstorm Outlook
Updated: Fri Sep 8 07:18:46 UTC 2017 (20170908 0730Z Day 3 shapefile | 20170908 0730Z Day 3 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20170908 0730 UTC Day 3 Outlook Graphic
Day 3 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MARGINAL 69,336 19,378,317 Jacksonville, FL...Miami, FL...Tampa, FL...St. Petersburg, FL...Hialeah, FL...
Probabilistic Graphic
20170908 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 % 69,454 19,381,623 Jacksonville, FL...Miami, FL...Tampa, FL...St. Petersburg, FL...Hialeah, FL...
   SPC AC 080718

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0218 AM CDT Fri Sep 08 2017

   Valid 101200Z - 111200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE FL
   PENINSULA AND COASTAL GA/SC...

   ...SUMMARY...
   A few brief tornadoes are possible across portions of the Florida
   Peninsula and coastal Georgia and South Carolina Sunday as Hurricane
   Irma impacts the region.

   ...Synopsis...
   Based on the latest forecast track from the National Hurricane
   Center, the center of Hurricane Irma is expected to be onshore
   across the far southern FL Peninsula. It is then expected to
   continue north-northwestward along the spine of the FL Peninsula,
   reaching the north-central FL Peninsula by 12Z Monday. Refer to the
   National Hurricane Center for the most up-to-date information
   regarding Hurricane Irma.

   Elsewhere, upper ridge extending from the southern Plains through
   the Great Basin will change little throughout the period. An upper
   low off the southern/central CA coast will drift slightly
   northward/northwestward while deepening. Shortwave trough initially
   over western portions of the Upper Midwest will eject northeastward
   into northwestern Ontario. 

   ...Hurricane Irma - FL Peninsula/Coastal GA and SC...
   Given the anticipated track of Irma, a tropical cyclone tornado
   environment will likely exist across the majority of the FL
   Peninsula during the day and then expand northward into coastal
   portions of GA and SC. Eastern portions of the FL Peninsula do not
   look overly favorable for tornadoes given the current forecast track
   but uncertainties regarding the actual track and the overall size
   and strength of the storm merit the inclusion of the entire
   peninsula in a 5% severe area.

   ...Southern CA...
   Mid-level flow around the eastern periphery of the upper low off the
   southern CA coast will increase Sunday evening/Monday morning as the
   system gradually deepens. This moderate, largely unidirectional flow
   will result favorable shear across the region. Airmass appears
   supportive of elevated thunderstorms over coastal portions of
   southern CA Sunday evening and overnight. Severe coverage is too
   uncertain at this time to introduce any probabilities across the
   region but outlook areas may be needed in subsequent forecast if
   confidence increases.

   ..Mosier.. 09/08/2017

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