(All days are valid from 12 UTC - 12 UTC the following day)
Note: A severe weather area depicted in the Day 4-8 period indicates 15%, 30% or higher probability for severe thunderstorms within 25 miles of any point.
PREDICTABILITY TOO LOW is used to indicate severe storms may be possible based on some model scenarios. However, the location or occurrence of severe storms are in doubt due to: 1) large differences in the deterministic model solutions, 2) large spread in the ensemble guidance, and/or 3) minimal run-to-run continuity.
POTENTIAL TOO LOW means the threat for a regional area of organized severe storms appears unlikely (i.e., less than 15%) for the forecast day.
Forecast Discussion
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 240900
SPC AC 240900
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Wed Apr 24 2024
Valid 271200Z - 021200Z
...DISCUSSION...
...D4/Saturday - Southern Plains into the upper Great Lakes...
An active severe thunderstorm episode appears possible on Saturday
across parts of the central and southern Plains, as a shortwave
trough and attendant strong mid/upper-level jet overspread a
generally warm and moist warm sector. A surface low is forecast to
deepen across southwest KS, with a dryline extending southward into
west TX. Thunderstorms are expected to develop near the dryline, and
potentially farther north/east within a moderate to strongly
unstable and weakly capped warm sector. Strong deep-layer shear will
support organized convection, including the potential for
supercells. There is some potential for rather early initiation and
evolution toward a complex convective mode with time, but any
supercells within this regime could become tornadic as low-level
shear/SRH notably increases during the afternoon/evening. A 30% area
has been added from south-central/southeast KS into OK and north TX,
where confidence is currently greatest regarding storm development
within the favorable environment described above.
A separate regime of severe potential could evolve from eastern IA
toward the upper Great Lakes, associated with the departing
shortwave trough and surface low. While this system will gradually
be weakening with time, storms could redevelop during the afternoon
within a moist and weakly capped environment, with deep-layer shear
remaining sufficiently strong for organized convection. Late in the
period, extensive convection that initially develops over the
central/southern Plains could also spread into parts of IA/IL/WI,
with some severe potential.
...D5/Sunday - ArkLaTex into the upper Midwest...
A corridor of organized severe potential could again evolve from the
ArkLaTex into the upper Midwest on D5/Sunday, as the strong
shortwave trough and attendant surface low move from the central
Plains towards the upper Great Lakes. Moderate instability and
favorable deep-layer shear could support a mix of supercells and
stronger storm clusters, though details remain uncertain at this
time.
...D6/Monday - ArkLaTex region into the lower MS Valley...
Some severe threat could linger into D6/Monday across the ArkLaTex
region into the lower MS Valley, as low-level moisture transport
persists near the remnant frontal zone. However, in the wake of the
departing upper trough, convection may tend to be less organized
compared to previous days.
..Dean.. 04/24/2024
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