Day 4-8 Severe Weather Outlook Issued on Oct 5, 2020
Updated: Mon Oct 5 08:37:02 UTC 2020
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, Oct 08, 2020 - Fri, Oct 09, 2020
D7
Sun, Oct 11, 2020 - Mon, Oct 12, 2020
D5
Fri, Oct 09, 2020 - Sat, Oct 10, 2020
D8
Mon, Oct 12, 2020 - Tue, Oct 13, 2020
D6
Sat, Oct 10, 2020 - Sun, Oct 11, 2020
(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 050835
SPC AC 050835
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0335 AM CDT Mon Oct 05 2020
Valid 081200Z - 131200Z
...DISCUSSION...
Medium-range models continue to indicate that an initially strong,
zonal mid/upper jet, emerging from the northern mid-latitude
Pacific, will undergo considerable amplification late this week
through next weekend. It appears that this will include the
evolution of significant large-scale troughing migrating inland of
the Pacific coast, across the Great Basin, Rockies and Great Plains
by early next week. By next Sunday, deepening surface troughing and
embedded cyclogenesis to the lee of the Rockies may contribute to
potential for the development of a substantive southerly return flow
off the Gulf of Mexico, which could continue into Monday. This
could contribute to sufficient destabilization to support the
evolution of organized severe storms across parts of the Great
Plains into Mississippi Valley, in the presence of strong vertical
shear.
However, considerable spread exists within and among the various
models concerning the synoptic and sub-synoptic developments, at
this extended range. And latest model output suggests that
deep-layered low-level moisture return may be complicated by the
preceding inland migration of a tropical cyclone late this week into
early next weekend.
This cyclone (currently Tropical Depression Twenty-Six) is forecast
to intensify to hurricane strength across the Gulf of Mexico within
the next few days, then migrate inland across the north central
Gulf coast by Friday night before weakening. It too could be
accompanied by a risk for severe weather, in the form of tornadoes.
However, reinforcement of potentially cool air across much of the
Gulf States, in the days prior to landfall, contributes to
uncertainty concerning the extent of this potential inland of
immediate coastal areas.
..Kerr.. 10/05/2020
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