Day 4-8 Severe Weather Outlook Issued on Jul 4, 2020
Updated: Sat Jul 4 08:21:03 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
Tue, Jul 07, 2020 - Wed, Jul 08, 2020
D7
Fri, Jul 10, 2020 - Sat, Jul 11, 2020
D5
Wed, Jul 08, 2020 - Thu, Jul 09, 2020
D8
Sat, Jul 11, 2020 - Sun, Jul 12, 2020
D6
Thu, Jul 09, 2020 - Fri, Jul 10, 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 040819
SPC AC 040819
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0319 AM CDT Sat Jul 04 2020
Valid 071200Z - 121200Z
...DISCUSSION...
Medium-range guidance continues to be in relatively good agreement
regarding the upper pattern into the middle of next week. A belt of
enhanced flow aloft will extend from the central West Coast
northeastward into the northern Plains/Canadian Prairie Provinces
and then eastward across Ontario into the Northeast States.
Latest runs of both the GFS and ECMWF forecast that a well-defined
shortwave trough will move through this belt of enhanced flow into
the northern High Plains on D4/Tuesday. Northwestward advection of
low-level moisture ahead of this system is expected to result in a
moderately to strongly unstable air mass from eastern MT into the
Dakotas. Strong southeasterly low-level flow beneath the enhanced
southwesterly aloft also supports ample vertical shear for organized
severe thunderstorms. Overall pattern matches with the potential for
an organized severe convective line. That being said, previous runs
did not forecast this shortwave until D5/Wednesday, leading to some
forecast uncertainty. Additionally, potential exists for the line to
develop near or north of the US/Canada border. These factors
preclude outlooking any areas but if current model trends hold,
probabilities will be needed in later outlooks.
The overall pattern looks to remain relatively unchanged through at
least D7/Friday. Several shortwaves are currently forecast to move
within the stronger flow into the northern Plains or Upper Midwest.
Severe thunderstorms are possible each time a shortwave trough
interacts with the instability expected to be in place. However,
predictability issues abound with this pattern, such as correctly
forecasting the strength of any of subtle shortwave troughs or any
remnant mesoscale boundaries. As such, no areas will be
highlighted, though daily risk areas will likely need to be
considered in subsequent outlooks.
..Mosier.. 07/04/2020
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