Day 4-8 Severe Weather Outlook Issued on Oct 18, 2017
Updated: Wed Oct 18 06:58:02 UTC 2017
Day 4 Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
15 %
93,314
11,390,140
Dallas, TX...Fort Worth, TX...Oklahoma City, OK...Tulsa, OK...Arlington, TX...
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
Sat, Oct 21, 2017 - Sun, Oct 22, 2017
D7
Tue, Oct 24, 2017 - Wed, Oct 25, 2017
D5
Sun, Oct 22, 2017 - Mon, Oct 23, 2017
D8
Wed, Oct 25, 2017 - Thu, Oct 26, 2017
D6
Mon, Oct 23, 2017 - Tue, Oct 24, 2017
(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 180656
SPC AC 180656
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0156 AM CDT Wed Oct 18 2017
Valid 211200Z - 261200Z
...DISCUSSION...
Medium-range models are in general agreement regarding the evolution
of a short-wave trough as it migrates across the western US late
this week before affecting the Plains/MS Valley during the day4/5
time period. While there remain timing differences among the models,
with the ECMWF being the fastest, most agree that significant height
falls will spread into the central Plains Saturday with lesser
certainty across lower latitudes into the day5 period. Higher-PW air
mass will advance northward across OK/KS prior to a strong frontal
passage and adequate instability should be in place for robust
convection along the surging boundary, including the possibility for
severe. For these reasons have introduced 15% severe probs from
eastern KS into north-central TX where greatest confidence in
buoyancy overlaps expected thunderstorm development. Predictability
decreases Sunday as models begin to diverge in their solutions.
However, some threat for strong storms may evolve across the upper
TX Coast into LA and this region will be monitored for possible
inclusion of severe probs in later outlooks.
..Darrow.. 10/18/2017
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