Mesoscale Discussion 0829
NWS Storm Prediction Center Norman OK
0549 PM CDT Mon May 31 2021
Areas affected...Parts of southwestern Texas
Concerning...Severe Thunderstorm Watch 229...
Valid 312249Z - 010045Z
The severe weather threat for Severe Thunderstorm Watch 229
SUMMARY...Discrete supercells may continue to develop across the
Davis and Glass Mountains vicinity into early evening, perhaps
gradually beginning to consolidate into cluster while approaching
the Del Rio, TX vicinity through 7-9 PM CDT. Trends are being
monitored for the possibility of an additional severe weather watch
southeast of Severe Thunderstorm Watch 229.
DISCUSSION...Relatively moist easterly/northeasterly near-surface
flow (associated with convective outflow/rain-cooled air) into the
northeastern slopes of the Davis and Glass Mountains, is
contributing to a corridor of strong boundary-layer instability
across the higher terrain. This is where lower/mid tropospheric
lapse rates remain steepest, aided by strongest heating and
boundary-layer mixing, and orographic forcing is contributing to
continuing thunderstorm initiation.
It appears that a 40 kt mid-level jet (around 500 mb), within
otherwise rather modest west-southwesterly deep-layer ambient mean
flow, is contributing to strong vertical shear, and this will
continue to support discrete supercell development into early
evening. Given these profiles, propagation will remain slow and to
the southeast. This will take storms both into northern Coahuila
and along the outflow boundary near the Rio Grande River, into areas near/northwest of Del Rio, TX through 00-02Z. It is possible that
storms and associated outflows might begin to consolidate into an
upscale growing and organizing cluster.
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