Day 4-8 Severe Weather Outlook Issued on May 18, 2020
Updated: Mon May 18 08:59:02 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, May 21, 2020 - Fri, May 22, 2020
D7
Sun, May 24, 2020 - Mon, May 25, 2020
D5
Fri, May 22, 2020 - Sat, May 23, 2020
D8
Mon, May 25, 2020 - Tue, May 26, 2020
D6
Sat, May 23, 2020 - Sun, May 24, 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 180857
SPC AC 180857
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0357 AM CDT Mon May 18 2020
Valid 211200Z - 261200Z
...DISCUSSION...
Spread among and within the various model output concerning
mid/upper flow evolution which will impact convective potential
becomes notable by Thursday and increases through the remainder of
the period. In general, it appears that an initially blocked regime
east of the Plains will be relatively short-lived, as mid-level
ridging over the Upper Midwest/Great Lakes region breaks down late
this work week, in response to significant troughing accelerating
across and north/northeast of the U.S. Rockies.
A more progressive regime may then prevail through the Memorial Day
Weekend. However, the ECMWF/ECENS suggests that the stronger
westerlies might tend to shift north of the Canadian/U.S. border by
the end of the period, while the GFS/GEFS maintain a branch of
stronger flow farther south, across at least the northern tier of
the United States. Embedded short wave perturbations could support
daily risks for some severe thunderstorm activity, particularly from
the lee of the northern and central Rockies into the Great Lakes
region. However, due to a combination of low predictability issues
and relatively low severe weather potential for the time of year,
severe probabilities for this time frame are less than 15 percent.
..Kerr.. 05/18/2020
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