Day 4-8 Severe Weather Outlook Issued on Jun 21, 2020
Updated: Sun Jun 21 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, Jun 24, 2020 - Thu, Jun 25, 2020
D7
Sat, Jun 27, 2020 - Sun, Jun 28, 2020
D5
Thu, Jun 25, 2020 - Fri, Jun 26, 2020
D8
Sun, Jun 28, 2020 - Mon, Jun 29, 2020
D6
Fri, Jun 26, 2020 - Sat, Jun 27, 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 210855
SPC AC 210855
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0355 AM CDT Sun Jun 21 2020
Valid 241200Z - 291200Z
...DISCUSSION...
...Wednesday/Day 4 and Thursday/Day 5...
The medium-range models begin the Day 4 to 8 period in reasonable
good agreement, with an upper-level ridge in the northern Rockies
and an upper-level trough in the Mississippi Valley. From Wednesday
into Thursday, the models move this upper-level trough eastward into
the southern and central Appalachians. Further to the west, a moist
airmass is forecast to advect northward across the Great Plains and
mid Mississippi Valley as an upper-level ridge moves into the
northern Plains. Although the ridge may suppress thunderstorm
development across much of the north-central U.S. Wednesday into
Thursday, isolated strong thunderstorm development will be possible
to the west of the ridge in the northern High Plains Thursday
afternoon. These storms could affect parts of the northern Plains
Thursday evening and overnight in the wake of the upper-level ridge.
A severe threat could develop but uncertainty remains substantial
concerning the amount of instability that will be in place.
...Friday/Day 6 to Sunday/Day 8...
On Friday and Saturday, the models move a shortwave trough from the
northern Plains eastward into the Great Lakes region. A cold front
is forecast move southeastward across the north-central states. This
boundary should be a focus for thunderstorm development. Strong to
potentially severe thunderstorm development could occur along and
near the front Friday afternoon from the mid Missouri Valley into
the Upper Mississippi Valley. A severe threat could again develop
along and near the front on Saturday from the central Plains to the
southern Great Lakes. However, predictability concerning instability
and the exact placement of the front Friday and Saturday afternoon
is substantial. Predictability remains problematic on Sunday as
model spread increases even more.
..Broyles.. 06/21/2020
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