Day 4-8 Severe Weather Outlook Issued on Jul 19, 2020
Updated: Sun Jul 19 09:00:02 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
Wed, Jul 22, 2020 - Thu, Jul 23, 2020
D7
Sat, Jul 25, 2020 - Sun, Jul 26, 2020
D5
Thu, Jul 23, 2020 - Fri, Jul 24, 2020
D8
Sun, Jul 26, 2020 - Mon, Jul 27, 2020
D6
Fri, Jul 24, 2020 - Sat, Jul 25, 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 190858
SPC AC 190858
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0358 AM CDT Sun Jul 19 2020
Valid 221200Z - 271200Z
...DISCUSSION...
A low-amplitude shortwave trough may continue moving across the
Northeast on Day 4/Wednesday. A marginal/isolated severe threat may
develop ahead of this feature across parts of this region as some
airmass destabilization occurs. Too much uncertainty exists
regarding the placement and coverage of these potentially strong to
severe storms to include 15% severe probabilities at this time.
Otherwise, mid-level heights are forecast to rise across the Plains
as an upper ridge builds over this region and central Canada.
Confidence is gradually increasing that a shortwave trough may
advance northeastward from the Rockies across the northern Plains on
Day 5/Thursday. Substantial low-level moisture return ahead of this
feature appears possible, which would potentially support strong
instability across the northern Plains. An organized severe threat
may ultimately develop across a portion of the northern Plains on
Day 5/Thursday, but there remains some spread in guidance regarding
both the timing and amplitude of the shortwave trough. Will not
include a 15% severe delineation for now, but severe potential
appears to be increasing.
Some severe risk may continue into Day 6/Friday with this shortwave
trough as it advances eastward across the Upper Midwest and Canada.
Thereafter, confidence quickly decreases in the evolution of this
feature as it moves across the Great Lakes, eastern Canada, and the
Northeast next weekend. Depending on its eventual track, a severe
threat may materialize across parts of these regions. Regardless,
confidence remains far too low to highlight a corridor of organized
severe potential at this extended time frame. Finally, some
medium-range guidance suggests the potential for another shortwave
trough to advance northeastward from the northern Rockies/Plains
into central Canada next weekend. If a more amplified upper trough
does develop, then an organized severe risk may ultimately develop
across parts of the northern Plains/Upper Midwest in the Day
7/Saturday to Day 8/Sunday time frame.
..Gleason.. 07/19/2020
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