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000
ACUS48 KWNS 230900
SWOD48
SPC AC 230859

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Tue Apr 23 2024

Valid 261200Z - 011200Z

...DISCUSSION...
A complex but active pattern is expected from D4/Friday through
D6/Sunday, as multiple mid/upper-level shortwave troughs impinge
upon a moist and unstable environment extending from the
southern/central Great Plains into parts of the Midwest and
Mississippi Valley.

...D4/Friday - Central/southern Plains into the mid MS Valley...
A negatively tilted shortwave trough is forecast to move
northeastward from the Great Plains toward the mid/upper MS Valley
on Friday. Most guidance suggests that convection developing late in
the D3/Thursday period will be ongoing Friday morning, potentially
posing an organized severe threat as it moves eastward. The
influence of early convection on warm sector evolution by Friday
afternoon/evening remains uncertain, but in general, moderate
destabilization will be possible along the Pacific front/dryline in
the wake of early convection, with some intensification of early
storms also possible farther east. Details regarding storm mode
remain uncertain at this forecast range, but in general, severe
storms capable of producing large hail, damaging winds, and a few
tornadoes will be possible across a broad region from the eastern
Great Plains into the mid MS Valley.

...D5/Saturday - Central/southern Plains into the Midwest/mid MS
Valley...
The negatively tilted shortwave trough and attendant occluding
surface cyclone are forecast to gradually weaken as they move across
the upper Great Lakes region on Saturday. Depending on timing of the
departing cyclone and magnitude of diurnal destabilization, some
severe-thunderstorm threat could evolve in advance of this system
through the afternoon across parts of WI/IL into MI, but confidence
remains too low to include 15% probabilities for this area.

Meanwhile, another strong shortwave trough is forecast to eject
across parts of the central/southern Plains Saturday afternoon and
evening, accompanied by strong surface cyclogenesis across the
central High Plains. Moderate to locally strong instability may
redevelop along/east of the dryline across central/western KS/OK
into north TX, as low-level and deep-layer shear strengthen through
the day. The synoptic pattern depicted by much of the extended-range
guidance is suggestive of an active severe thunderstorm episode
along/ahead of the dryline, though some guidance (notably recent
runs of the ECMWF) suggest potential for early development across
parts of OK/north TX, which could complicate the scenario by late
afternoon/evening. Some severe threat could spread toward parts of
the mid MS Valley late in the period.

...D6/Sunday - ArkLaTex into parts of the Midwest...
Predictability begins to decrease by late in the weekend, though in
general, a mid/upper-level trough and attendant surface low are
forecast to move from the central Plains toward the upper Great
Lakes region. A corridor of severe thunderstorm potential is
forecast to extend south-southwestward from the surface low, as a
trailing cold front moves through a moist, unstable, and favorably
sheared environment. A 15% area has been added where confidence is
currently greatest in severe-thunderstorm potential Sunday afternoon
and evening.

..Dean.. 04/23/2024