Day 4-8 Severe Weather Outlook Issued on Jul 20, 2020
Updated: Mon Jul 20 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
Thu, Jul 23, 2020 - Fri, Jul 24, 2020
D7
Sun, Jul 26, 2020 - Mon, Jul 27, 2020
D5
Fri, Jul 24, 2020 - Sat, Jul 25, 2020
D8
Mon, Jul 27, 2020 - Tue, Jul 28, 2020
D6
Sat, Jul 25, 2020 - Sun, Jul 26, 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 200858
SPC AC 200858
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Mon Jul 20 2020
Valid 231200Z - 281200Z
...DISCUSSION...
A shortwave trough should move northeastward across the northern
Plains on Day 4/Thursday, as upper ridging remains prominent over
the central CONUS. Low-level moisture is forecast to surge northward
across the Dakotas through the day, and storms may form by peak
heating Thursday afternoon across this area. The forecast
combination of instability and shear would potentially support
organized severe storms. Will defer possible inclusion of 15% severe
probabilities across the northern Plains to a later outlook, as some
questions remain concerning both the timing/amplitude of the
shortwave trough and coverage of storms. Some severe risk could
continue across parts of the Upper Midwest on Day 5/Friday and the
Upper Great Lakes region on Day 6/Saturday as the shortwave trough
moves into Canada, although predictability remains low.
By the upcoming weekend, another upper trough may advance eastward
across western into central Canada. Glancing large-scale ascent
associated with this upper trough may overspread parts of the
northern Plains, with an organized severe risk possible. However,
confidence is low in this scenario occurring given substantial
differences in medium-range guidance regarding the strength and
placement of this upper trough.
..Gleason.. 07/20/2020
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