Day 4-8 Severe Weather Outlook Issued on May 20, 2020
Updated: Wed May 20 08:57:03 UTC 2020
Day 4 Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
15 %
90,635
951,227
Grand Island, NE...Kearney, NE...Fremont, NE...North Platte, NE...Norfolk, NE...
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, May 23, 2020 - Sun, May 24, 2020
D7
Tue, May 26, 2020 - Wed, May 27, 2020
D5
Sun, May 24, 2020 - Mon, May 25, 2020
D8
Wed, May 27, 2020 - Thu, May 28, 2020
D6
Mon, May 25, 2020 - Tue, May 26, 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 200855
SPC AC 200855
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0355 AM CDT Wed May 20 2020
Valid 231200Z - 281200Z
...DISCUSSION...
Latest medium-range model output indicates that a vigorous short
wave trough will emerge from the Great Basin and accelerate
northeastward across the Rockies into the northern Plains on
Saturday. Large-scale forcing for ascent appears likely to focus
strongest thunderstorm development across the Plains, south and east
of the Black Hills, into adjacent portions of the middle Missouri
Valley through Saturday night. Northward low-level moisture return
into deep surface troughing seems likely to support at least
moderately large mixed-layer CAPE beneath rather steep lower/mid
tropospheric lapse rates. Although deep-layer shear might be fairly
modest, thermodynamic profiles will be favorable for the development
of strong cold pools and rear inflow in consolidating convection.
The evolution of a organized, southeastward propagating severe
convective system appears possible, initially accompanied by the
risk for severe hail, then increasing potential for strong surface
gusts.
Continuing severe weather potential into Sunday is more unclear,
ahead of an eastward and southeastward advancing cold front, from
southern portions of the central Plains into the Upper Midwest.
Much may hinge on the extent and uncertain influence of convective
cloud cover and outflow from convection Saturday night.
Thereafter, as the strong mid-level impulse progresses into Ontario
by early next week, stronger, more zonal mid-latitude westerlies may
shift into or north of the Canadian/U.S. border vicinity. As this
occurs, potential for organized severe weather on a regional scale
may diminish for a period. However, it is possible that this could
change by the middle of next week, when latest model output suggests
significant mid-level trough amplification is possible across the
central Canadian/U.S. border vicinity.
..Kerr.. 05/20/2020
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