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Mesoscale Discussion 0537
NWS Storm Prediction Center Norman OK
0737 PM CDT Fri Apr 22 2022

Areas affected...Central/Northern South Dakota

Concerning...Severe Thunderstorm Watch 142...143...

Valid 230037Z - 230200Z

The severe weather threat for Severe Thunderstorm Watch 142, 143
continues.

SUMMARY...The severe threat continues across WW 142 and 143. Severe
storms may persist into the late evening and necessitate a watch
extension or new watch issuance across portions of northern South
Dakota.

DISCUSSION...An east-west oriented corridor of strong/severe storms
have emerged along a northward advecting warm front across portions
of central South Dakota. A well-mixed boundary layer is impinging on
the southern periphery of these storms, and has advected into the
southern portions of WW 142 and 143, characterized by MLCAPE near
2500 J/kg and effective shear of 35-45 kt. Thus, storms have
exhibited discrete/embedded supercell modes, with hail to 1.75
inches in diameter being reported thus far.

The current expectation is for storms to persist into the remainder
of the evening hours and continue to pose a threat for large hail
and damaging wind gusts. However, it remains uncertain how far north
the severe threat will be maintained. Forecast soundings indicate a
sharp north-south gradient in surface-based instability. North of
the surface boundary, steep mid-level lapse rates co*bined with
persistent low-level warm/moist air advection and sufficient
deep-layer shear should support a threat for elevated severe
convection within a relatively co*pact zone. Thus, convective trends
will continue to be monitored, and should the severe threat persist
a watch extension, or perhaps a new watch, may be needed across
portions of northern South Dakota.

..Karstens.. 04/23/2022

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...FSD...ABR...UNR...

LAT...LON   44009812 43899996 43820197 44620227 45260116 45809945
            45679794 44969733 44009812