Day 4-8 Severe Weather Outlook Issued on Jan 23, 2021
Updated: Sat Jan 23 09:44:03 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
Tue, Jan 26, 2021 - Wed, Jan 27, 2021
D7
Fri, Jan 29, 2021 - Sat, Jan 30, 2021
D5
Wed, Jan 27, 2021 - Thu, Jan 28, 2021
D8
Sat, Jan 30, 2021 - Sun, Jan 31, 2021
D6
Thu, Jan 28, 2021 - Fri, Jan 29, 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 230942
SPC AC 230942
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0342 AM CST Sat Jan 23 2021
Valid 261200Z - 311200Z
...DISCUSSION...
Medium-range models are in reasonable agreement with respect to
evolution of large-scale features through Day 6, after which
divergence in solutions increases through the end of the period.
Even early on in the period, however, differences at smaller scales
-- particularly with an upper short-wave trough ejecting from the
Southwest across the southern tier of the U.S. during the first half
of the period -- complicate assessment of convective potential.
Models generally agree in the maintenance of persistent western U.S.
upper troughing, with the aforementioned short-wave feature progged
to eject eastward, crossing the Four Corners states and eventually
emerging into the central/southern Plains Day 4 (Tuesday). By Day 5
(Wednesday), as the feature shifts across the Mid and lower
Mississippi Valley and then the Mid South and central Gulf Coast
states, surface cyclogenesis is expected to occur. With the GFS
stronger/sharper with the upper feature, stronger surface
cyclogenesis is depicted, with a deepening low over the Tennessee
Valley area by Wednesday evening, while the weaker ECMWF solution
places a much weaker low over the southern Alabama/southern Georgia
vicinity. In either case however, it appears likely that the
boundary layer will remain stable, as a strong baroclinic zone over
the northern Gulf of Mexico just ahead of this system will likely be
slow to retreat northward. Thus, severe weather is not expected
with this system.
As the system moves offshore Day 6 (Thursday), large-scale ridging
will prevail over much of the country, ahead of re-establishment of
western U.S. troughing. Therefore, severe weather is not expected
Thursday, and then beyond which pattern predictability diminishes
steadily through the end of the period.
..Goss.. 01/23/2021
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