(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 040859
SPC AC 040859
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Mon Jul 04 2022
Valid 071200Z - 121200Z
...DISCUSSION...
Large-scale upper ridging should gradually amplify across much of
the High Plains, Rockies, and central Canada from Day 4/Thursday
into Day 5/Friday. Rich low-level moisture is forecast to remain
over much of the northern Plains into the Midwest, Ohio Valley, and
eastern states to the south of a front in this time frame. Robust
thunderstorm development may occur across parts of these regions
each afternoon/evening as strong instability develops with daytime
heating. Greater severe potential should be tied to weak,
low-amplitude shortwave troughs which will traverse the apex of the
ridge and then proceed generally east-southeastward. The
placement/evolution of these features, some of which should be
convectively induced/augmented, remains difficult at this extended
time frame. Even though predictability remains low, some severe
probabilities should eventually be needed across parts of the
northern Rockies/Plains, Midwest, OH Valley, and perhaps parts of
the Mid-Atlantic/Carolinas on both Thursday and Friday once
mesoscale details become clearer.
Medium-range guidance is coming into better agreement that an
amplified shortwave trough may progress east-northeastward across
the Pacific Northwest, northern Rockies/Plains, and central Canada
this upcoming weekend. This feature should suppress the upper ridge
to some extent, with surface cyclogenesis possible across some
portion of the northern Plains into Canada. An organized severe
thunderstorm episode may occur as the shortwave trough moves across
these regions from Day 6/Saturday into Day 7/Sunday. If the timing
and evolution of this feature remain consistent in guidance, then
15% severe areas may eventually be needed for both days across some
portion of the northern Plains and perhaps the Upper Midwest.
..Gleason.. 07/04/2022
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