South Dakota Mesoscale Discussion

Areas affected…eastern Nebraska…western and northern
Iowa…southeastern Minnesota…and parts of western Wisconsin

Concerning…Severe potential…Watch unlikely

Valid 190328Z – 190530Z

Probability of Watch Issuance…20 percent

SUMMARY…Thunderstorms should continue to develop across the MCD
area, with potential that a few instances of hail — and possibly
wind gusts — approach severe levels. A WW is not anticipated, due
to the expected local/limited risk.

DISCUSSION…Latest radar loop shows thunderstorms developing over
the eastern Nebraska vicinity, near and to the cool side of a
surface cold front, roughly in line with CAM forecasts across this
region. The storms are developing atop a stabilizing — and for the
most part post-frontal — boundary layer, which should serve to
limit severe potential.

With that said, steep lapse rates aloft above the decoupling
boundary layer — as sampled by area 00Z RAOBs — are contributing
to substantial elevated CAPE. This will permit a few
stronger/possibly rotating updrafts to evolve from time to time,
aided by marginally sufficient shear through the cloud-bearing
layer. With storms which can develop nearer the front, a locally
stronger wind gust or two may occur. However, hail approaching or
exceeding severe levels will remain the greater risk with the most
robust storms. At this time, risk is expected to remain
sufficiently limited such that WW issuance is likely to remain
unnecessary. However, we will continue to monitor storm evolution,
for signs of robust development in close proximity to the advancing
front, which would — given greater risk for wind in such a scenario
— warrant greater concern with respect to WW necessity.

..Goss/Edwards.. 09/19/2019

…Please see for graphic product…


LAT…LON 41259780 41939762 44559420 45489252 44889140 43299183
40939554 40669715 41259780

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