Valid 210100Z – 211200Z
…THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST
TEXAS AND EASTERN OKLAHOMA ACROSS ARKANSAS AND INTO SOUTHERN
MISSOURI…
…SUMMARY…
Severe thunderstorms are expected to affect parts of eastern
Oklahoma, northeast Texas, Arkansas, and southern Missouri this
evening and overnight. Damaging winds, large hail, and tornadoes are
all possible.
…Northern TX and eastern OK into AR and southern MO…
Cooling aloft continues over the central and southern Plains with
the approach of the upper trough, with increasing winds aloft as
well. Meanwhile, surface analysis shows mid 60s F dewpoints now to
the Red River and into central AR, and this low-level moisture will
continue to spread north as a southwesterly low-level jet increases
to around 50 kt later this evening. Despite the loss of heating,
instability will continue to increase ahead of the developing cold
front due to both cooling aloft and low-level theta-e advection.
Effective SRH will exceed 300 m2/s2 this evening which will enhance
the supercell and tornado threat. The greatest tornado threat
appears to be over far northeast TX, southeast OK, and into
southwest AR where surface moisture will be most abundant. The 00Z
FWD sounding shows a minor capping inversion, which will be lessened
as the evening progresses. Meanwhile, the 00Z OUN sounding shows
steeper lapse rates with no capping inversion, but with marginal
moisture content. As this environment spreads east, it will
incorporate an increasingly moist air mass with a few tornadoes
expected. A strong tornado is possible.
Farther north, large-scale forcing for ascent will be maximized,
with only marginal instability initially. With time, a QLCS is
expected, with locally significant damaging wind gusts possible
across northern AR and into southern MO.
For more information see mesoscale discussions 2085 and 2087.
..Jewell.. 10/21/2019
$$