Day 4-8 Severe Weather Outlook Issued on Oct 18, 2020
Updated: Sun Oct 18 08:57:03 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
Wed, Oct 21, 2020 - Thu, Oct 22, 2020
D7
Sat, Oct 24, 2020 - Sun, Oct 25, 2020
D5
Thu, Oct 22, 2020 - Fri, Oct 23, 2020
D8
Sun, Oct 25, 2020 - Mon, Oct 26, 2020
D6
Fri, Oct 23, 2020 - Sat, Oct 24, 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 180855
SPC AC 180855
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0355 AM CDT Sun Oct 18 2020
Valid 211200Z - 261200Z
...DISCUSSION...
...Wednesday/Day 4 and Thursday/Day 5...
On Wednesday, the medium-range models are in reasonable agreement,
with an upper-level trough in the western U.S. and
west-southwesterly mid-level flow in the central and eastern U.S.
The models are forecasting an axis of low-level moisture to be
located in the Arklatex and mid Mississippi Valley. Isolated
thunderstorms may form along the northern edge of the moist sector
from the central Plains into the mid Mississippi Valley Wednesday
afternoon and evening but weak instability is expected to keep any
severe threat marginal.
On Thursday, the models move an upper-level trough into the Rockies
as southwest mid-level flow becomes established in the north-central
states. At the surface, a cold front is forecast to move
southeastward into the central Plains and upper Mississippi Valley.
Thunderstorms could develop Thursday afternoon and evening along the
front. However, weak instability should again keep any severe threat
marginal.
...Friday/Day 6 to Sunday/Day 8...
The models continue in reasonable agreement from Friday to Saturday,
moving the cold front southeastward across the eastern third of the
nation. Thunderstorms will be possible along and ahead of the front
from the Ozarks into the mid Mississippi Valley on Friday and in the
Southeast on Saturday. Weak instability should again keep any severe
threat marginal. On Sunday, an upper-level trough is forecast to
move eastward across the southwestern states with southwest
mid-level flow located in the southern Plains. Thunderstorms will be
possible in the southern and central Plains Sunday into Sunday night
but the models have varying degrees of instability ahead of the
system. Due to significant model spread, predictability remains
quite low for Sunday.
..Broyles.. 10/18/2020
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