ZCZC SPCSWOD48 ALL
   ACUS48 KWNS 220812
   SPC AC 220812

   Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0312 AM CDT Tue Apr 22 2025

   Valid 251200Z - 301200Z

   ...DISCUSSION...
   ...Days 4-5/Fri-Sat -- Central/Southern Plains...

   An upper ridge will build over the Plains toward the MS Valley this
   weekend as a deepening upper trough develops over the western U.S.
   Some lead shortwave impulses will likely migrate through the ridge,
   and southwesterly flow increases over the central/southern Rockies.
   At the surface, persistent south/southeasterly low-level flow will
   maintain a warm advection regime across the southern/central Plains,
   while a daily surface dryline evolves over the High Plains. While
   some severe potential may occur Friday and Saturday over parts the
   central/southern Plains, uncertainty remains quite high given
   several periods of convection leading into Friday, as well as
   ongoing convection Friday morning, and possible capping concerns
   beneath the upper ridge both days. This precludes 15 percent
   probability delineation at this time, but probabilities may be
   needed in subsequent outlooks as smaller scale details become better
   resolved.

   ...Days 6-8/Sun-Tue -- Great Plains to the Upper Midwest...

   A more active severe weather period is possible early next week as
   the western U.S. trough develops eastward into the Plains and Great
   Lakes vicinity. The upper trough may begin ejecting into the
   southern/central Plains as early as Day 6/Sun. However, the timing
   of this feature may be ill-timed with peak diurnal
   heating/destabilization such that stronger large-scale ascent and
   increasing southwesterly flow aloft arrive overnight. Forecast
   soundings Sunday afternoon suggest capping may limit convection.

   By Day 7/Mon, a strong midlevel jet streak should overspread
   portions of the central/southern Plains into the Upper Midwest. Lee
   cyclogenesis is forecast across the central High Plains, resulting
   in a sharpening dryline across portions of the Great Plains, and
   warm front extending across the eastern Dakotas to the Mid-MS
   Valley. Rich Gulf moisture will be in place across the warm sector
   and widely scattered severe storms appear possible from Monday
   afternoon into Monday night. As is typical at longer time frames,
   forecast guidance differs in exact timing and placement of key
   features. However, the overall pattern is favorable for an
   all-hazards severe weather episode, and a 15 percent delineation has
   been included, though this area may shift over the coming days as
   details become better resolved. 

   Severe potential may continue into Day 8/Tue across portions of the
   Midwest to the southern Plains as a shortwave upper trough continues
   across the Great Lakes into southeast Canada, and a cold front
   impinges southeastward over portions of the region. Uncertainty
   increases considerably during this time, precluding 15 percent
   probabilities at this time.

   ..Leitman.. 04/22/2025

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