Day 4-8 Severe Weather Outlook Issued on Apr 8, 2018
Updated: Sun Apr 8 08:56:03 UTC 2018
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
15 %
116,285
6,381,058
Shreveport, LA...Little Rock, AR...Springfield, MO...Tyler, TX...Fort Smith, AR...
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, Apr 11, 2018 - Thu, Apr 12, 2018
D7
Sat, Apr 14, 2018 - Sun, Apr 15, 2018
D5
Thu, Apr 12, 2018 - Fri, Apr 13, 2018
D8
Sun, Apr 15, 2018 - Mon, Apr 16, 2018
D6
Fri, Apr 13, 2018 - Sat, Apr 14, 2018
(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 080854
SPC AC 080854
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0354 AM CDT Sun Apr 08 2018
Valid 111200Z - 161200Z
...DISCUSSION...
The primary feature of interest during the extended period will be a
deep/amplified mid-level trough that will reach the central US by
D6/Fri. As it does so, strengthening west/southwesterly flow aloft
will transport steep lapse rates over much of the southern/central
Plains. Meanwhile, a robust low-level mass response will feature a
narrow corridor of enhanced poleward theta-e transport, generally
from eastern Texas to the lower Missouri Valley. As a dry line and
cold front accelerate east across the region, low/mid-level ascent
is forecast to strengthen sufficiently to overcome convective
inhibition and promote thunderstorms from eastern Texas to parts of
the Midwest through Friday night.
While medium-range guidance continues to exhibit run-to-run
variability with regards to the amplitude/timing of the trough, most
deterministic/ensemble guidance suggest strong/severe thunderstorms
will be most likely from eastern Texas to the Ozarks and Mid-South
Friday afternoon through the overnight. Within this corridor,
vigorous low/mid-level wind fields should overlap adequate
surface-based buoyancy, such that all severe hazards may be possible
with maturing convection. Therefore, a 15-percent probability has
been introduced with this forecast cycle. Further refinements of
this area (with some potential for a northward expansion) will
likely be needed in future updates.
The trough will advance further east through D7/Sat-D8/Sun, with
pockets of strong/severe convection potentially persisting across
areas from the Ohio Valley south to the Gulf Coast. Despite this
potential, uncertainties regarding availability of adequate
instability, the eastward evolution of the trough, and subsequent
timing/placement of stronger convection remain too high to introduce
probabilities beyond D6/Fri.
..Picca.. 04/08/2018
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