Day 4-8 Severe Weather Outlook Issued on Aug 29, 2020
Updated: Sat Aug 29 08:51:02 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 01, 2020 - Wed, Sep 02, 2020
D7
Fri, Sep 04, 2020 - Sat, Sep 05, 2020
D5
Wed, Sep 02, 2020 - Thu, Sep 03, 2020
D8
Sat, Sep 05, 2020 - Sun, Sep 06, 2020
D6
Thu, Sep 03, 2020 - Fri, Sep 04, 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 290849
SPC AC 290849
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0349 AM CDT Sat Aug 29 2020
Valid 011200Z - 061200Z
...DISCUSSION...
...Tuesday/Day 4 and Wednesday/Day 5...
The medium-range models including the ECMWF, GFS, Canadian and UKMET
are in reasonable agreement on Tuesday, moving an upper-level trough
into the southern High Plains. Southwest mid-level flow is forecast
across the much of the southern Plains where MCS development will be
possible Tuesday evening. A severe threat along with a potential for
wind damage and hail may occur with the stronger storms associated
with the MCS.
On Wednesday, the models move the upper-level trough across Texas. A
very moist airmass is forecast to be in place ahead of the trough
over the eastern half of Texas. Thunderstorms that develop ahead of
the trough Wednesday afternoon could have a chance to become severe.
Wind damage and hail would be possible.
Although the models are in reasonable agreement on Tuesday and
Wednesday, there is still too much uncertainty to introduce a 15%
contour, mainly due to issues with instability and timing of the
trough.
...Thursday/Day 6 to Saturday/Day 8...
From Thursday to Saturday, the GFS moves the upper-level trough
slowly eastward across the southern U.S. The ECMWF has a different
solution with the upper-level trough remaining in the southern
Plains and becoming dampened out. Thunderstorms will be possible
each day ahead of the upper-level trough. Although a severe threat
will be possible Thursday and Friday afternoon in parts of the
southern Plains, this scenario would be more likely if the ECMWF
were to verify. At this point, uncertainty is substantial from
Thursday to Saturday.
..Broyles.. 08/29/2020
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