Mesoscale Discussion 0415
NWS Storm Prediction Center Norman OK
1119 PM CDT Fri Apr 23 2021
Areas affected...Parts of southeastern Oklahoma...northeast Texas...southwestern Arkansas
Concerning...Severe Thunderstorm Watch 103...
Valid 240419Z - 240615Z
The severe weather threat for Severe Thunderstorm Watch 103
SUMMARY...Although substantive further intensification appears
unlikely, an organized cluster of thunderstorms may be accompanied
by strong surface gusts occasionally approaching severe limits as it
continues across the Red River Valley vicinity, toward the
Ark-La-Tex region, through Midnight-2 AM CDT. Given the generally
marginal nature of the continuing severe risk, a new severe weather
watch is not anticipated, but trends will continue to be monitored.
DISCUSSION...An organized cluster of thunderstorms continues to
propagate east-southeastward around 30 kt, across the Red River
Valley vicinity. This appears focused along the leading edge of
stronger cooling aloft (associated with the mid-level cold core of
the vigorous short wave trough progressing east of the southern
Rockies), supported by warm advection along a remnant frontal zone
associated stronger daytime differential surface heating and
boundary-layer mixing. While this frontal zone becomes gradually
weaker with east-southeastward extent, inflow of moist air with
moderately large CAPE in excess of 1000 J/kg may maintain this
activity into the 05-07Z time frame.
Although activity appears generally rooted above a relatively cool
near-surface layer stable layer, and is embedded within a rather
modest deep-layer westerly flow regime, shear within the convective
layer appears strong. And a 30-50+ kt rear inflow jet appears to
have developed, with a few strong surface gusts approaching severe
limits occasionally reaching the surface, based on Oklahoma mesonet observations.
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