SPC AC 180545

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1245 AM CDT Sat May 18 2024

   Valid 181200Z - 191200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN NORTH FL AND
   SOUTH GA...

   ...SUMMARY...
   The most probable corridor for damaging winds is across the Florida
   Panhandle to the South Atlantic Coast, this morning into the
   afternoon. Isolated damaging winds and sporadic severe hail will be
   possible during the afternoon into the evening across much of the
   Southeast, and over parts of the Upper Midwest to eastern Kansas.

   ...Southeast...
   Increasing convective development is expected this morning across
   the northern Gulf Coast region from LA to the FL Panhandle. This
   should occur in response to isentropic ascent within the 700-mb
   baroclinic zone, amid a difluent upper flow regime in the right-rear
   quadrant of an intense upper jet advancing northeast over the Deep
   South to southern Appalachians. Outflow from a Friday evening MCS
   that decayed over south GA and north FL should serve as the primary
   downstream baroclinic zone later this morning as convection
   consolidates and spreads east-northeast. 

   Amid a relatively nebulous surface pattern due to the lack of
   cyclogenesis, low-level flow outside of convective influences should
   remain weak. Southwesterly deep-layer speed shear will be favorable
   for occasional linear clustering through the morning into the
   afternoon before convection moves off the southern Atlantic Coast.
   Scattered damaging winds from strong to isolated severe wind gusts
   remain possible.

   Additional storms should form along the Florida Atlantic Coast sea
   breeze during the afternoon with an isolated severe threat possible.
   At least scattered afternoon thunderstorms are expected over the TN
   Valley to southern Appalachians ahead of the primary shortwave
   impulse embedded within the positive-tilt, southern-stream trough.
   Uncertainty exists over the degree of destabilization in the wake of
   the extensive morning convection farther south-southeast. With only
   moderate deep-layer shear expected between the trough and the
   mid-level jet near the Gulf Coast, have held severe wind/hail
   probabilities at level 1-MRGL.

   ...Upper Midwest to KS...
   A shortwave trough across the Prairie Provinces into the northern
   Great Plains will move east into far northwest ON by early Sunday. 
   Attendant surface cyclone will track more north-northeastward as it
   occludes, with the trailing cold front shifting east of the Upper MS
   Valley and south in KS during the afternoon. Low-level convergence
   along the front should be sufficient for isolated to scattered
   thunderstorms, as a moderately unstable airmass with MLCAPE of
   1000-2000 J/kg becomes established at peak heating. 

   The bulk of strong mid-level west-southwesterlies will remain
   confined behind the front. Moderate deep-layer shear should
   overspread the Lake Superior region, as flow substantially weakens
   with southern extent. Isolated severe hail and damaging winds will
   be most likely across the Upper Midwest portion of the area. Locally
   strong to severe wind gusts and small hail may also occur within the
   weakly sheared environment along the front into KS. The severe
   threat will wane after dusk.

   ..Grams/Bentley.. 05/18/2024

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z