Day 4-8 Severe Weather Outlook Issued on Jul 30, 2020
Updated: Thu Jul 30 08:49:02 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
Sun, Aug 02, 2020 - Mon, Aug 03, 2020
D7
Wed, Aug 05, 2020 - Thu, Aug 06, 2020
D5
Mon, Aug 03, 2020 - Tue, Aug 04, 2020
D8
Thu, Aug 06, 2020 - Fri, Aug 07, 2020
D6
Tue, Aug 04, 2020 - Wed, Aug 05, 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 300847
SPC AC 300847
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0347 AM CDT Thu Jul 30 2020
Valid 021200Z - 071200Z
...DISCUSSION...
Further consolidation of troughing within initially split branches
of westerlies east of the Rockies may occur late this weekend into
early next week, along a positively tilted axis curving across
Quebec into the Mississippi Valley. However, flow to the south of
this axis appears likely to become broadly anticyclonic, on the
northwestern periphery of building subtropical ridging.
Medium-range guidance suggests that a convectively generated or
enhanced lower/mid tropospheric perturbation progressing through
this regime may maintain considerable strength into Sunday, and
perhaps Monday, across the lower Great Lakes/northern Mid Atlantic
Coast states into New England. This may be accompanied by a
modestly deep surface cyclone, with a moderate to strongly sheared
and moist warm sector, which could prove supportive of convection
capable of producing potentially damaging wind gusts and perhaps a
couple of tornadoes. However, there has been considerable spread
evident within and among the various models concerning these
developments, contributing to uncertainties that result in the
maintenance of less than 15 percent severe probabilities at this
time.
Similar uncertainties exist concerning the evolution and track of
Isaias, which could impact parts of the south Atlantic Seaboard
Sunday into Monday.
Thereafter, through the middle of next week, flow across the U.S.
may trend less amplified, but with stronger westerlies remaining
north of the international border, across the British Columbia coast
into the Canadian Prairies. This could be accompanied by the
eastward advection of elevated mixed-layer air into the Great
Plains. However, due to drying in the wake of the amplified eastern
troughing, destabilization may be initially modest.
In general, it appears that severe thunderstorm activity will remain
sparse in coverage and/or relatively minor in nature.
..Kerr.. 07/30/2020
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