Day 4-8 Severe Weather Outlook Issued on Oct 21, 2020
Updated: Wed Oct 21 09:00:03 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
Sat, Oct 24, 2020 - Sun, Oct 25, 2020
D7
Tue, Oct 27, 2020 - Wed, Oct 28, 2020
D5
Sun, Oct 25, 2020 - Mon, Oct 26, 2020
D8
Wed, Oct 28, 2020 - Thu, Oct 29, 2020
D6
Mon, Oct 26, 2020 - Tue, Oct 27, 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 210858
SPC AC 210858
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Wed Oct 21 2020
Valid 241200Z - 291200Z
...DISCUSSION...
...Saturday/Day 4 to Sunday/Day 5...
The medium-range models are in decent agreement on Saturday,
establishing southwest flow from the Great Plains into the Great
Lakes. At the surface, a cold and dry airmass will be in place
across much of the central and northeastern U.S. Thunderstorms could
develop in parts of the Gulf Coast States Saturday afternoon but
weak instability is expected to limit any severe threat.
On Sunday, the models reinforce the cold airmass in the central U.S.
as a front moves quickly southward into the southern Plains and mid
Mississippi Valley. Thunderstorms will be possible along the front,
mainly from the mid Mississippi Valley into the southern Great
Lakes. Instability will most likely be weak ahead of the front,
keeping any severe threat marginal Sunday afternoon.
...Monday/Day 6 to Wednesday/Day 8...
Southwest mid-level flow is maintained by the model solutions on
Monday and Tuesday as a cold front moves from the Ohio and Tennessee
Valleys into the Southeast. Thunderstorms could develop along the
front Monday and Tuesday afternoon. However, instability is forecast
to be very weak suggesting a severe threat would be limited.
On Wednesday, the models solutions diverge. Some models move an
upper-level low into the southern Plains during the day. Other
solutions move the upper-level low through the Desert Southwest.
This solutions move the system into the central Rockies Wednesday
night. Under that scenario, thunderstorms associated with a marginal
severe risk could develop in the Red River Valley Wednesday night as
low-level moisture return occurs. However, uncertainty is very high
due to the large spread of model solutions.
..Broyles.. 10/21/2020
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