SPC AC 280544

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1244 AM CDT Wed Sep 28 2022

   Valid 281200Z - 291200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF THE FLORIDA SPACE COAST...

   ...SUMMARY...
   Several tornadoes will be possible across the Florida Peninsula
   today, in association with Hurricane Ian.

   ...Synopsis...
   Across the eastern CONUS, a broad positively tilted mid-level trough
   is forecast to accelerate eastward as it slowly weakens. Enhanced
   steering flow near the base of the trough should allow Hurricane Ian
   to move inland over the Florida Peninsula later today. Meanwhile, an
   upper low is forecast to slowly weaken across the Pacific Northwest
   as it impinges upon the western edge of a quasi stationary ridge
   over the central CONUS. 

   At the surface, a remnant front along the southeastern coast will
   gradually become more ill-defined as Ian approaches, while strong
   high pressure will remain in place over the Great Lakes. 

   ...Florida...
   As Major Hurricane Ian approaches the Florida Gulf coast this
   afternoon/evening (see NHC for latest track info), strong easterly
   flow will support increasing shear and deep tropical moisture across
   the southern and central Florida Peninsula. Surface dewpoints of
   75-80 F observed near Miami and the southeastern coast should
   gradually shift northward as southeasterly flow strengthens across
   the eastern hemisphere of the low-level circulation. Hi-res model
   soundings and plan views show continued enlargement of low-level
   hodographs (ESRH 300-500 m2/s2) ahead of developing spiral bands
   containing semi-discrete convection and numerous embedded
   mesocyclones. While the large central dense overcast will likely
   limit surface heating, drier air wrapping into the southwestern
   portion of the circulation may support scattered cloud breaks
   between bands to the east, with locally greater
   heating/destabilization. Otherwise, the strongest updrafts should
   remain tied to the inland advection of higher theta-e air (70-80 F
   surface dewpoints) northeast of the center across the eastern
   peninsula. 

   HREF guidance continues to indicate the most favorable zone for
   tornadoes should gradually shift north toward the Space Coast early
   this morning. The aforementioned quasi-stationary front across the
   northern Peninsula may also serve as a focus for supercells and
   tornadoes given the favorable orientation of the shoreward spiral
   bands and 20-30 kt southeasterlies orthogonal to the boundary. 10%
   tornado probabilities have been added to account for locally greater
   tornado potential along the stalled front where further low-level
   shear enhancement is possible.

   ..Lyons/Darrow/Wendt.. 09/28/2022

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