Day 4-8 Severe Weather Outlook Issued on Jan 24, 2021
Updated: Sun Jan 24 11:47:04 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
Wed, Jan 27, 2021 - Thu, Jan 28, 2021
D7
Sat, Jan 30, 2021 - Sun, Jan 31, 2021
D5
Thu, Jan 28, 2021 - Fri, Jan 29, 2021
D8
Sun, Jan 31, 2021 - Mon, Feb 01, 2021
D6
Fri, Jan 29, 2021 - Sat, Jan 30, 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 241144
SPC AC 241144
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0544 AM CST Sun Jan 24 2021
Valid 271200Z - 011200Z
...DISCUSSION...
Latest runs of the medium-range models show fair model-to-model
agreement with respect to large-scale features into Day 6 (Friday
Jan. 29), though even larger-scale similarities between models fade
further into the second half of the period. This increasing
large-scale disagreement centers around timing of the ejection of a
short-wave trough across the southwestern U.S. Day 6, and then
into/across the central U.S. Day 7. Depending upon evolution of
this feature, convective potential could increase over the south
central and later the southeastern U.S. during the second half of
the period. However, predictability concerns in this time frame
preclude any further assessment of convective potential.
Prior to this, through the first half of the period, a short-wave
trough is forecast to move from the central/southern Plains region
at the beginning of the period (Wednesday Jan. 27), to the East
Coast states by the start of Day 5. Slight differences in the
strength of this feature between the GFS and ECMWF result in more
notable deviations in depiction of associated surface low intensity,
with the GFS more aggressive in terms of surface cyclone development
over the southern Appalachians area, and thus more bullish with
respect to convective potential. With the ECMWF showing a much more
muted frontal wave much farther south -- shifting from the Gulf
Coast to the southeast Georgia coast -- confidence remains too low
to render a more thorough assessment.
As this upper feature moves offshore Day 5, strong cyclogenesis is
progged over the Gulf Stream/western Atlantic, with cold high
pressure building southward in its wake, across the eastern half of
the country -- in tandem with large-scale ridging/anticyclonic flow
across most of the CONUS.
..Goss.. 01/24/2021
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