Day 4-8 Severe Weather Outlook Issued on May 7, 2020
Updated: Thu May 7 08:55:02 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
Sun, May 10, 2020 - Mon, May 11, 2020
D7
Wed, May 13, 2020 - Thu, May 14, 2020
D5
Mon, May 11, 2020 - Tue, May 12, 2020
D8
Thu, May 14, 2020 - Fri, May 15, 2020
D6
Tue, May 12, 2020 - Wed, May 13, 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 070852
SPC AC 070852
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0352 AM CDT Thu May 07 2020
Valid 101200Z - 151200Z
...DISCUSSION...
Severe potential will be low on Day 4/Sunday as the overall pattern
will not be too much different than on Day 3/Saturday. Strong
surface high pressure will persist east of the Rockies with scant
boundary-layer moisture/instability. By Day 5/Monday, surface high
pressure will continue to limit severe potential. However, a
strengthening lee surface trough beneath an upper ridge over the
Intermountain region will allow modest return flow across the TX Rio
Grande Valley toward the west TX mountains and southeast NM plains.
Severe potential will likely still remain low as overall shear and
instability are forecast to be weak.
Beginning Day 6/Tuesday, Gulf moisture return should begin to
increase northward across TX and into OK. Surface high pressure will
still persist across much of the eastern two-thirds of the CONUS,
but will begin to lift northeast toward the Midwest and Mid-Atlantic
vicinity, rather than being centered over the Plains and Southeast.
The GFS and ECMWF show a similar trend Day 6/Tuesday through Day
8/Thursday. However, the GFS is trending about 12 hours faster with
features relevant to severe thunderstorm potential compared to the
ECMWF. Overall the trend is for the western upper ridge to shift
eastward, becoming positioned over the Plains on Day 6/Tuesday or
Day 7/Wednesday. This should allow increasing southerly low level
flow to transport rich Gulf moisture northward across the
southern/central Plains ahead of a digging western trough. By Day
8/Thursday, a shortwave is forecast to eject across the central
Plains toward the Upper Midwest.
Confidence is low at this time to pinpoint exact areas of 15% or
greater severe probabilities due to aforementioned timing
differences, and the stubborn nature of the anomalously strong
surface high pressure system over the eastern U.S. early in the
period. However, the overall trends suggest that multiple periods of
severe potential will exist across the Plains and into portions of
the mid/upper MS Valley Day 6/Tuesday through Day 8/Thursday.
..Leitman.. 05/07/2020
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