Day 4-8 Severe Weather Outlook Issued on May 18, 2023
Updated: Thu May 18 09:02:03 UTC 2023
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 21, 2023 - Mon, May 22, 2023
D7
Wed, May 24, 2023 - Thu, May 25, 2023
D5
Mon, May 22, 2023 - Tue, May 23, 2023
D8
Thu, May 25, 2023 - Fri, May 26, 2023
D6
Tue, May 23, 2023 - Wed, May 24, 2023
(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 180900
SPC AC 180900
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0400 AM CDT Thu May 18 2023
Valid 211200Z - 261200Z
...DISCUSSION...
Medium-range models are in general agreement regarding evolution of
the synoptic pattern over the U.S. through the medium range.
As an upper trough progresses across the eastern U.S. early next
week, a second trough is forecast to expand gradually over the West,
and linger there through the period. Downstream, in the wake of the
departing eastern trough, ridging will become established.
As the eastern trough progresses, a surface cold front will continue
moving eastward across the western Atlantic, and southward into the
Gulf, with a stout area of high pressure expanding across the
eastern two-thirds of the country in the wake of the front. This
area of high pressure will therefore largely keep higher theta-e air
confined to the far southern U.S. -- i.e. Texas and Florida --
through the period.
Greatest severe-weather potential will likely reside over the High
Plains, evolving Day 5 to 6, and then lingering there with a noted
diurnal (afternoon/evening) peak. This will occur as modest
moisture leaks northward across the High Plains on southerly flow on
the back side of the broad area of surface high pressure. With weak
westerly/southwesterly flow aloft across the Rockies, a lee trough
will likely be maintained. As such, subtle disturbances in the flow
aloft will likely focus favored areas along the lee trough for
afternoon convective development, that would then tend to progress
southeastward given the low-level southeasterly flow regime. With
elevated mixed-layer air/steep lapse rates in place, modest
instability, and a wind profile veering from southeasterly to
southwesterly with height and a nocturnal low-level jet evolving
each evening, it would appear that clusters of strong/severe storms
will be possible each afternoon which would then spread
southeastward toward lower elevations.
With that said, picking out areas/days where risk may be greater
than the background low-level threat is difficult, given the subtle
forcing, and thus no risk areas will be included at this time.
..Goss.. 05/18/2023
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