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Mesoscale Discussion 1282
NWS Storm Prediction Center Norman OK
0536 PM CDT Fri Jun 24 2022

Areas affected...portions of central and eastern South Dakota into
north-central Nebraska

Concerning...Severe Thunderstorm Watch 408...

Valid 242236Z - 250000Z

The severe weather threat for Severe Thunderstorm Watch 408
continues.

SUMMARY...The severe threat continues across Severe Thunderstorm
Watch 408. Very large hail and severe wind gusts are possible with
the more mature, sustained supercell structures. Upscale growth into
an intense squall line with significant severe winds is possible
later this evening. A WW issuance may eventually be needed later
across eastern South Dakota.

DISCUSSION...MRMS mosaic radar data depicts multiple supercells
underway across central SD into northern NE, with 50 dBZ echo tops
approaching 45 kft and MESH swaths indicating hail up to 2 inches in
diameter. Up to 6000/4500 J/kg SBCAPE/MLCAPE characterize the
ambient thermodynamic environment ahead of the supercells. 22Z
mesoanalysis and RAP forecast soundings indicate that this high
buoyancy is driven by surface-500 mb 8.5 C/km mid-level lapse rates
and rich low-level moisture. Given modest strengthening and veering
of the vertical wind profile, 25-40 kts of effective bulk shear
coincides with the extreme instability. As such, 2+ inch hail and
severe gusts (perhaps 75+ mph) may acco*pany the most intense
supercells through the evening hours.

Storm/cold-pool mergers may support the development of a more
organized, leading-line/trailing-precipitation MCS during the
evening. The steep, deep-layered lapse rates overspreading a
relatively mixed boundary layer would support a more organized,
significant severe wind threat under the condition such an MCS
develops. A separate MCD will be issued to address this threat
should the development of a bow-echo MCS beco*es apparent. Either
way, organized severe storms are expected to approach the eastern
bounds of Severe Thunderstorm Watch 408, and a new WW issuance may
eventually be needed later this evening.

..Squitieri.. 06/24/2022

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

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

LAT...LON   42709998 42410073 42390133 45059985 45629883 45759795
            45459707 44939675 44399681 43739747 43139883 42709998