SPC AC 080547

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1247 AM CDT Sun Sep 08 2024

   Valid 081200Z - 091200Z

   ...NO SEVERE THUNDERSTORM AREAS FORECAST...

   ...SUMMARY...
   The organized severe-thunderstorm threat is expected to be low on
   Sunday.

   ...Synopsis and Discussion...
   A mature mid-latitude cyclone, embedded within larger upper
   troughing, is forecast to progress northeastward from southern
   Quebec into northeastern Quebec. Another shortwave trough is
   expected to move through the western portion of the parent upper
   troughing, dropping across western Ontario and the Upper Great Lakes
   Sunday evening into Monday morning. Isolated thunderstorms are
   possible with this second wave late Sunday night into early Monday
   morning. Evolution of these shortwaves will help maintain troughing
   across much of the eastern CONUS throughout the period.

   Farther west, upper ridging will gradually move eastward into the
   Plains while a low-amplitude shortwave trough moves through the
   Pacific Northwest and into the northern Rockies. 

   At the surface, expansive high pressure centered over the Mid MS
   Valley will dominate the sensible weather from the Mid MS and OH
   Valleys into much of the central and southern Plains. This should
   keep any low-level moisture confined to the immediate Gulf Coast and
   FL Peninsula. A stationary front will likely extend from a low over
   the far western Gulf of Mexico northeastward through northern FL.
   Thunderstorms are possible in the vicinity of this boundary
   throughout the day, with the highest coverage expected over the
   northern/central FL Peninsula. Abundant cloud cover will limit
   heating across northern/central FL Peninsula, and lapse rates will
   be poor. However, mid-level flow around 40 kt may support enough
   vertical shear for a few more persistent/organized updrafts capable
   of damaging gusts. Even so, severe coverage is expected to remain
   less than 5%. 

   Afternoon thunderstorms are expected again from the central High
   Plains into parts of the central/southern Rockies, Great Basin, and
   Southwest. High-based character of these storms could result in a
   few locally strong gusts. Isolated high-based thunderstorms are also
   possible from the interior Pacific Northwest into the northern
   Rockies as a shortwave trough progresses through the region. A few
   strong gusts are possible with these storms as well. In both of
   these areas, overall severe coverage is expected to remain less than
   5%.

   ..Mosier/Lyons.. 09/08/2024

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