(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 200859
SPC AC 200859
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Sat Apr 20 2024
Valid 231200Z - 281200Z
...DISCUSSION...
...Tuesday/Day 4 and Wednesday/Day 5...
An upper-level ridge is forecast to move eastward from the
Intermountain West on Tuesday into the Rockies on Wednesday. At the
surface, a large high pressure area is forecast to move across the
southeastern U.S. In the wake of the high, moisture return will
likely take place across the southern and central Plains on
Wednesday and Wednesday night. It appears that elevated
thunderstorms may develop on the northern edge of the moist sector
as the low-level jet strengthens. These storms could be associated
with a severe threat, having a potential for large hail and damaging
wind gusts. However, predictability remains low concerning any
specific scenario, mainly due to the presence of the upper-level
ridge.
...Thursday/Day 6 to Saturday/Day 8...
By Thursday, the models have a moist airmass in place across most of
the southern and central Plains. The upper-level ridge is forecast
to move eastward into the Mississippi Valley, as an upper-level
trough moves into the Desert Southwest. As this feature approaches
the central U.S., isolated to scattered strong to severe
thunderstorms will be possible to the east of a dryline from
northwest Texas northward into west-central Kansas. The primary
threats would be isolated large hail and wind damage, although an
isolated tornado threat would also be possible.
On Friday, the upper-level trough is forecast to move across the
central Plains. Model forecasts suggest that a moist and unstable
airmass will be in place from the southern and central Plains
extending into the Upper Midwest. This would be the favored area for
scattered severe storms Friday afternoon and evening. On Saturday,
some model solutions suggest a large-scale upper-level trough will
develop over the southwestern U.S., with southwest mid-level flow
remaining in place over much of the south-central U.S. Although
spread among the solutions is somewhat large by Saturday, the models
suggest a moist and unstable airmass will be in place across parts
of the south-central states. Storms that develop within this airmass
would have potential to be severe. However, predictability at this
range remains too low to outlook a threat area.
..Broyles.. 04/20/2024
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