(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 210900
SPC AC 210900
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Thu Sep 21 2023
Valid 241200Z - 291200Z
...DISCUSSION...
...D4/Sunday: Southern Plains into the ArkLaTex region...
An occluding cyclone is forecast to weaken over the northern Plains
on Sunday, with any threat for organized severe storms likely to be
confined to parts of the southern Plains and ArkLaTex region,
along/south of a cold front. Extended-range guidance generally
suggests that a low-amplitude midlevel shortwave trough will move
from the southern Rockies into the southern Plains on Sunday, though
considerable spread remains regarding the track and intensity of
this feature, and also regarding the cold-frontal position by Sunday
afternoon. The shortwave trough may be favorably timed to support
vigorous storm development Sunday afternoon/evening near and south
of the cold front, with some severe threat potentially evolving
across some portion of the southern Plains into the ArkLaTex region.
...D5/Monday - D8/Thursday...
A few strong storms may be possible early next week across parts of
TX, though weakening deep-layer flow/shear should keep any severe
threat relatively isolated. Another mid/upper-level trough may
induce cyclogenesis across some portion of the High Plains by mid
week, though initial moisture return will tend to be somewhat
limited, and predictability remains low regarding any notable
increase in severe potential in association with this system.
..Dean.. 09/21/2023
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