Day 4-8 Severe Weather Outlook Issued on Sep 12, 2020
Updated: Sat Sep 12 07:50:03 UTC 2020
Day 4 Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Day 5 Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Day 6 Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Day 7 Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Day 8 Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
D4
Tue, Sep 15, 2020 - Wed, Sep 16, 2020
D7
Fri, Sep 18, 2020 - Sat, Sep 19, 2020
D5
Wed, Sep 16, 2020 - Thu, Sep 17, 2020
D8
Sat, Sep 19, 2020 - Sun, Sep 20, 2020
D6
Thu, Sep 17, 2020 - Fri, Sep 18, 2020
(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 120748
SPC AC 120748
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0248 AM CDT Sat Sep 12 2020
Valid 151200Z - 201200Z
...DISCUSSION...
Overall severe potential appears limited through the Day 4-8 period.
Broad upper ridging is forecast to persist across much of the CONUS
through Day 5/Wed, with any stronger westerly flow confined to the
international border vicinity. By the second half of the period, the
upper-level pattern is forecast to become more amplified and
progressive as a trough moves over the western states through the
weekend, and a series of troughs spread across the eastern U.S.
While guidance varies in timing, at least one cold front should
traverse parts of the Midwest mid-to-late week. However,
higher-quality moisture and instability are likely to be offset from
stronger forcing and shear, limiting severe potential.
Some severe threat, in the form of tropical cyclone-related tornado
activity could impact parts of the central Gulf Coast early in the
period as current T.D. 19 moves inland, as forecast by the National
Hurricane Center. However, uncertainty is too great at this time
frame to include severe probabilities.
..Leitman.. 09/12/2020
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