Day 4-8 Severe Weather Outlook Issued on Mar 19, 2021
Updated: Fri Mar 19 08:56:03 UTC 2021
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, Mar 22, 2021 - Tue, Mar 23, 2021
D7
Thu, Mar 25, 2021 - Fri, Mar 26, 2021
D5
Tue, Mar 23, 2021 - Wed, Mar 24, 2021
D8
Fri, Mar 26, 2021 - Sat, Mar 27, 2021
D6
Wed, Mar 24, 2021 - Thu, Mar 25, 2021
(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 190854
SPC AC 190854
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Fri Mar 19 2021
Valid 221200Z - 271200Z
...DISCUSSION...
Medium-range models appear to be in good agreement into Day 6
(Wednesday), after which differences emerge amongst model solutions.
Day 4 (Monday), a rather vigorous southern-stream short-wave trough
is forecast to shift out of the southern Rockies and into the
southern Plains. This will induce surface cyclogenesis, with the
developing low shifting from the southern High Plains across
Oklahoma/Kansas through the afternoon and evening. However,
returning low-level air from the Gulf of Mexico in response to
increasing southerly low-level flow will be incompletely modified,
owing to presence of surface high pressure -- and associated
cool/subsident airmass -- residing over the Gulf in advance of this
system. As such, minimal CAPE is expected at best, and thus no more
than minimal severe risk would be expected, as a result.
As the upper system and associated surface low turn northward Day 5,
moving toward the upper Mississippi Valley/Upper Great Lakes region
in a bit of a Fujiwara-like manner in advance of the next western
system, a trailing surface cold front should settle just off the
Texas coast, over the far northwestern Gulf of Mexico.
By Day 6, as the next, western system crosses the Southwest and
moves into the southern Plains, surface wave formation will likely
occur along the remnant front. The GFS depicts this cyclogenesis
near or just off the Texas coast, while the ECMWF is much farther
offshore with the surface boundary, and thus with the frontal wave
development. While the more optimistic scenario in terms of onshore
convective potential would suggest possible, lower-end severe risk,
this small-scale uncertainty between the models precludes any areal
risk delineation.
Beyond Day 6, models begin more substantial deviation in solutions,
with the advance of this upper system, and the related evolution of
the associated surface pattern. As such, a decrease in
confidence/predictability prevails through the end of the period.
..Goss.. 03/19/2021
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