Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Kansas City, MO...Omaha, NE...Lincoln, NE...Overland Park, KS...Kansas City, KS...
SPC AC 110600
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Tue Aug 11 2020
Valid 121200Z - 131200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN PLAINS...
...SUMMARY...
Severe thunderstorms with wind damage and isolated large hail will
be possible across parts of the northern Plains on Wednesday
afternoon and evening. Marginally severe thunderstorms will be
possible in parts of the lower to mid Missouri Valley.
...Northern Plains...
An upper-level trough will move across the northwestern U.S. on
Wednesday as southwest mid-level flow becomes established across the
northern Plains. A 55 to 65 kt mid-level jet will move northeastward
from the northern Rockies into southern Saskatchewan. At the
surface, a cold front will advance eastward across the northern High
Plains. A moist airmass will be in place across much of the Dakotas
where moderate to strong instability is forecast by afternoon.
Thunderstorms appear most likely to develop across far western North
Dakota by late afternoon with this activity moving
east-northeastward into west-central North Dakota during the
evening.
NAM and GFS Forecast soundings in western North Dakota near and to
the north of Dickinson for 00Z/Thursday have surface dewpoints in
the lower 60s F with MLCAPE around 2000 J/kg. 0-6 km shear values
are forecast to be near 30 kt with 700-500 mb lapse rates near 8.5
C/km. This environment would be marginal for supercells. But
organized multicells or semi-organized rotating storms will be
possible. Isolated large hail and wind damage will be the primary
threats.
The main problem with this forecast is model inconsistency
concerning convective coverage. 700 mb temperatures are forecast to
gradually warm during the day across western North Dakota, which
would inhibit convective initiation. The time most likely for
convective initiation would be during the late afternoon or early
evening as low-level flow ramps up across the region. Although the
potential for severe thunderstorm development appears conditional,
the presence of the mid-level jet to the northwest should help
increase convective coverage in the evening. For this reason, have
placed a small slight risk far parts of the northern Plains for this
outlook.
...Lower to Mid Missouri Valley...
A shortwave ridge is forecast to move eastward across the central
Plains on Wednesday. A moist and unstable airmass will be in place
beneath the ridge from eastern Kansas north-northwestward into
southern South Dakota. Due to the upper-level ridge and limited
large-scale ascent, convective coverage is expected to remain
isolated. In spite of warm air aloft, 0-6 km shear is forecast to be
in the 20 to 30 kt range near the upper-level ridge axis. This
combined with steep lapse rates may be enough for a marginal wind
damage and hail threat late Wednesday afternoon.
..Broyles.. 08/11/2020
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NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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