Valid 301300Z – 311200Z
…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PARTS OF THE
HIGH PLAINS TO SOUTHERN GREAT PLAINS AND SOUTH-CENTRAL MO TO
SOUTHWEST OH…
…SUMMARY…
Isolated severe thunderstorms are possible across parts of the High
Plains into the southern Great Plains, and separately from
south-central Missouri to southwest Ohio, mainly through early
evening.
…High Plains…
Post-frontal upslope flow will be common from northeast NM to
eastern WY today, maintaining upper 40s to mid 50s surface dew
points at peak heating. This should support a plume of modest MLCAPE
of 500-1500 J/kg. Confluent mid-level westerlies will generally be
confined to the WY portion of the region where 500-mb flow of 35-45
kt is anticipated, with weaker winds southward along the Front
Range. Isolated to scattered thunderstorms are expected to develop
by mid to late afternoon over the higher terrain. A few of these
storms should become supercellular for a couple hours across eastern
WY to northeast CO. Abundant MLCIN with eastward extent on the
plains and lack of stronger forcing for ascent should keep severe
hail and wind coverage low.
…South-central MO to southern OH…
An MCV over west-central MO should drift east towards the Mid-MS
Valley before stalling tonight. Ongoing convection ahead of the MCV
is decaying, yielding confidence that diabatic surface heating may
become adequate for redevelopment later this afternoon. Should this
overlap the narrow corridor of enhanced low-level shear/vorticity
attendant to the MCV, the risk for a couple supercells capable of a
tornado and isolated damaging wind may be realized. Farther east, a
weakly convergent surface front might aid in small multicell
clusters capable of locally damaging wind.
…Southern Great Plains…
Composite outflow/effective front has reached southern OK into the
TX Panhandle as a decaying MCS continues to push towards the
Ark-La-Tex. Low-level warm advection atop the composite boundary has
aided in persistent redevelopment across western OK. Marginally
severe hail and wind will be possible with this latter activity,
mainly through midday as the low-level jet subsides. Reference MCD
1898 for additional short-term information. Surface-based late
afternoon development will probably be confined to the TX Panhandle
vicinity near the intersection of the composite outflow/front and
dryline. Weakening deep-layer shear across the region will serve to
limit the overall threat.
..Grams/Leitman.. 08/30/2019
$$