687
ACUS48 KWNS 220813
SWOD48
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