Day 4-8 Severe Weather Outlook Issued on Feb 22, 2021
Updated: Mon Feb 22 09:17:02 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
Thu, Feb 25, 2021 - Fri, Feb 26, 2021
D7
Sun, Feb 28, 2021 - Mon, Mar 01, 2021
D5
Fri, Feb 26, 2021 - Sat, Feb 27, 2021
D8
Mon, Mar 01, 2021 - Tue, Mar 02, 2021
D6
Sat, Feb 27, 2021 - Sun, Feb 28, 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 220915
SPC AC 220915
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0315 AM CST Mon Feb 22 2021
Valid 251200Z - 021200Z
...DISCUSSION...
Blocking may linger within the large-scale pattern across the
southern mid-latitude and subtropical eastern Pacific late this week
into the beginning of next week. However, the latest medium-range
guidance indicates that prominent/amplified mid-level ridging,
forecast to evolve across the eastern Pacific during the middle to
latter portion of this week, will become increasingly suppressed by
a series of significant short wave perturbations emerging from the
upstream westerlies.
Mid-level flow inland of the Pacific coast appears likely to become
increasingly split, with a number of embedded progressive short wave
perturbations. The northern branch is currently forecast to
maintain a relatively low amplitude with a west-northwesterly
component, to the southwest of an elongated deep vortex centered
just north of Hudson Bay. Within the southern branch, it appears
that relatively amplified mean troughing will develop across the
Pacific Coast into the Great Plains.
At the same time, subtropical ridging may become increasingly
prominent across much of the Gulf of Mexico into the Southeast.
This regime may become increasingly conducive to significant surface
cyclogenesis to the lee of the southern Rockies by next
Sunday/Monday, as boundary-layer moistening continues over the Gulf
of Mexico (particularly the southwestern Gulf). Associated
large-scale forcing for ascent and destabilization could support
increasing severe thunderstorm potential across parts of the
southern Great Plains into the middle/lower Mississippi Valley.
However, much will hinge on the shorter wavelength developments,
which are still fairly uncertain at this extended range. One
particular concern is the timing of the northern branch short waves,
and their associated southward surges of colder air to the lee of
the Rockies, relative to the emerging southern branch short waves,
which could displace and/or mitigate the risk for severe storms.
..Kerr.. 02/22/2021
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