Day 4-8 Severe Weather Outlook Issued on Aug 5, 2020
Updated: Wed Aug 5 09:05:03 UTC 2020
Day 4 Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
15 %
70,404
624,339
Sioux Falls, SD...Rapid City, SD...Mitchell, SD...Pierre, SD...Yankton, SD...
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, Aug 08, 2020 - Sun, Aug 09, 2020
D7
Tue, Aug 11, 2020 - Wed, Aug 12, 2020
D5
Sun, Aug 09, 2020 - Mon, Aug 10, 2020
D8
Wed, Aug 12, 2020 - Thu, Aug 13, 2020
D6
Mon, Aug 10, 2020 - Tue, Aug 11, 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 050903
SPC AC 050903
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0403 AM CDT Wed Aug 05 2020
Valid 081200Z - 131200Z
...DISCUSSION...
...Northern Plains to Upper Midwest Vicinity...
Strong ridging will persist across the southern/central tier of the
U.S. for much of the Day 4-8 period, maintaining seasonally hot
conditions with low severe potential. However, northern stream flow
will remain active near the U.S./Canadian border as a series of
shortwave trough migrate across the Canadian Prairie provinces,
resulting in enhanced mid/upper westerly flow. Seasonally moist
conditions will persist across the north-central U.S. and multiple
episodes of strong to severe thunderstorms will be possible From the
Dakotas/Nebraska eastward to the Upper Midwest, mainly Day 4/Sat
through at least Day 6/Mon.
On Day 4/Sat, a cold front sagging northeast to southwest from
western MN into northern NE will modify as strong warm advection
spreads northward across the central Plains ahead of a shortwave
impulse. Storms are expected to develop in upslope southeasterly low
level flow in the vicinity of this boundary across western SD/NE
during the afternoon or early evening. As a low level jet increases
during the evening/overnight, upward development into an eastward
propagating MCS appears possible, and damaging winds are possible
across parts of SD/NE.
By early-to-middle of next week, a stronger/deeper trough is
forecast to shift eastward across the region, and a stronger surface
cold front may eventually drop southward across much of the Plains
and portions of the Midwest, bringing more settled conditions
by/just after the end of the forecast period. While the overall
pattern appears favorable for multiple days of active convection
across the northern Plains/Upper Midwest vicinity Day 5/Sun through
at least Day 6/Mon, where exactly convection will develop each day
is uncertain and will be driven by prior days storms and mesoscale
processes/features that are not well resolved at longer time-scales.
Severe probabilities will likely be needed in subsequent outlooks
and trends will be monitored.
..Leitman.. 08/05/2020
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