Day 4-8 Severe Weather Outlook Issued on May 15, 2020
Updated: Fri May 15 08:57:03 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
Mon, May 18, 2020 - Tue, May 19, 2020
D7
Thu, May 21, 2020 - Fri, May 22, 2020
D5
Tue, May 19, 2020 - Wed, May 20, 2020
D8
Fri, May 22, 2020 - Sat, May 23, 2020
D6
Wed, May 20, 2020 - Thu, May 21, 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 150854
SPC AC 150854
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Fri May 15 2020
Valid 181200Z - 231200Z
...DISCUSSION...
As at least a couple of significant short wave perturbations pivot
around its southern and eastern periphery, amplified large-scale
mid-level troughing appears likely to progress inland of the U.S.
Pacific coast early next week. As it does, downstream mid-level
ridging over the Plains may continue to build northward, through
portions of southern Manitoba and northwestern Ontario, while an
evolving mid-level low within initially branching flow to the east
digs across and southeast of the Ohio River.
By mid-week, as an upstream short wave trough digs into the Pacific
Northwest, it appears that the bulk of the larger-scale troughing
will pivot and accelerate north-northeastward out of the Great
Basin, into and through the Canadian Prairies and northern U.S.
Plains. As this occurs, it appears that the eastern mid-level low
may become cut off from the stronger westerlies, somewhere across or
to the lee of the southern Appalachians, before only slowly
beginning to accelerate northeastward across the Mid Atlantic Coast
vicinity by late next week.
In association with this regime, severe weather potential seems
likely to remain relatively low across most areas through the
period. One exception could develop across parts of the Dakotas and
adjacent areas of the northern Plains, where an influx of low-level
moisture into the warm sector of a developing significant cyclone
could contribute substantive destabilization in the presence of
strong vertical shear, Wednesday through Wednesday night. This
environment could become conducive to supercell development and the
evolution of one or two upscale growing, organized thunderstorm
clusters. While severe probabilities are being maintained at less
than 15 percent due to lingering uncertainties (and low
predictability issues), this could change in subsequent outlooks for
this time period.
..Kerr.. 05/15/2020
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