Mesoscale Discussion 1426
NWS Storm Prediction Center Norman OK
0607 PM CDT Fri Aug 06 2021
Areas affected...Parts of southern South Dakota and northern
Concerning...Severe Thunderstorm Watch 409...
Valid 062307Z - 070100Z
The severe weather threat for Severe Thunderstorm Watch 409
SUMMARY...The evolution of an increasingly organized convective
system capable of producing severe hail and strong surface gusts in
excess of 50 kt appears possible near the South Dakota/Nebraska
vicinity, into the Valentine vicinity by 8-9 PM CDT. Trends are
being monitored for the possibility of a new severe weather watch
east of WW 409.
DISCUSSION...Stronger thunderstorm development may be consolidating
a bit west of Chadron NE, near/east of the Wyoming/South
Dakota/Nebraska border vicinity, aided by weak lower/mid level warm
advection ahead of an approaching short wave trough. This appears
focused along the southern periphery of a broad zone of strong
differential surface heating, beneath the northern/northeastern edge
of warmer and more strongly capping elevated mixed-layer air.
Near surface/low-level convergence also appears focused along the
zone, extending eastward along the South Dakota/Nebraska border
vicinity. Easterly low-level flow near and north of this boundary
is contributing to strong deep-layer shear beneath 30+ kt westerly
500 mb flow, while strongest and deepest boundary-layer mixing has
occurred along and to the south of the frontal zone.
Although mixed-layer CAPE is relatively modest to weak across the
higher plains to the west of Valentine, the environment may still be
conducive to the evolution of a gradually intensifying and
organizing thunderstorm cluster through 00-02Z. As this occurs,
there probably will be increasing potential for convection to
produce a swath of severe wind gusts in excess of 50 kt, as it
approaches the Valentine vicinity.
= = =
To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at firstname.lastname@example.org and ask to be removed from WX-STORM. ------------=_1628291291-54770-1562--