Day 4-8 Severe Weather Outlook Issued on Sep 18, 2022
Updated: Sun Sep 18 08:56:03 UTC 2022
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
Wed, Sep 21, 2022 - Thu, Sep 22, 2022
D7
Sat, Sep 24, 2022 - Sun, Sep 25, 2022
D5
Thu, Sep 22, 2022 - Fri, Sep 23, 2022
D8
Sun, Sep 25, 2022 - Mon, Sep 26, 2022
D6
Fri, Sep 23, 2022 - Sat, Sep 24, 2022
(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 180854
SPC AC 180854
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Sun Sep 18 2022
Valid 211200Z - 261200Z
...DISCUSSION...
...Wednesday/Day 4 to Friday/Day 6...
During the midweek time frame, an upper-level trough is forecast to
move from the Great Lakes region into the Northeast. At the surface,
a cold front is forecast to advance eastward into the lower Great
Lakes. Ahead of the front, instability is forecast to be weak ahead
of the system. However, large-scale ascent should be quite focused
just ahead of the trough, which could enable a line of strong
thunderstorms to develop in parts of the Northeast Wednesday
afternoon and evening. Although there could be potential for a
severe threat in parts of New York and Pennsylvania, the upper-level
trough is timed late. For this reason, will hold off on adding a
severe threat area at this time.
On Thursday, a large upper-level high pressure system will be in
place across much of the southern U.S. as an upper-level trough
moves across the northern Rockies. The trough is forecast to move
through the northern Plains on Friday. Moisture return ahead of the
system should be weak. Although some thunderstorm development will
be possible ahead of the trough both on Thursday afternoon and
Friday afternoon, the weak instability is expected to keep any
severe threat marginal and isolated across the north-central U.S.
...Saturday/Day 7 and Sunday/Day 8...
The upper-level system in the northern U.S. is forecast to become
less amplified on Saturday, moving eastward into the Great Lakes.
Isolated thunderstorms will be possible near the upper-level trough
during the afternoon, but weak instability should marginalize any
severe-weather potential. On Sunday, the models develop an
upper-level trough larger in scale across the mid Mississippi
Valley. Ahead of the system, low-level moisture could return
northward into parts of the Southeast. If this where to happen,
scattered thunderstorm development would be possible ahead of the
trough across parts of the Tennessee Valley and southern
Appalachians Sunday afternoon. At this time, there are some
significant differences in the model solutions, suggesting there is
considerable uncertainty late in the Day 4 to 8 period.
..Broyles.. 09/18/2022
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