Day 1 Severe Weather Outlook

Valid 251200Z – 261200Z


A few strong storms with gusty winds and hail are possible over
parts of southern Kansas/Missouri and northern Oklahoma/Arkansas, as
well as across parts of Arizona on Wednesday afternoon and evening.

Broad upper troughing/cyclonic flow is expected to persist over the
northern half of the U.S. today, while an upper low lingers across
southern California/southern Arizona and adjacent northwest Mexico.

At the surface, a cold front is forecast to advance
east-northeastward across the Great Lakes and into eastern Canada,
while sagging more slowly southward across the central U.S. By
latter stages of the period, the front should extend from the lower
Great Lakes/Ohio Valley westward to Oklahoma and the Texas Panhandle
region. This front — and the southwest U.S. low — will focus the
two main areas of convection this period.

…Southeast KS/northern and eastern OK/southern MO/northern AR…
Daytime heating of a very moist pre-frontal boundary layer will
contribute to strong destabilization across parts of
Kansas/Oklahoma, and eastward into parts of Arkansas and southern
Missouri. Some convection may be ongoing at the start of the period
across the region, with redevelopment of storms expected by early
afternoon — near both the sagging front, as well as remnant
convective outflows.

Though deep-layer shear will not be particularly strong,
moderate/veering flow with height will likely — given the favorable
background thermodynamic environment — contribute to a few stronger
storms, that may grow upscale and congeal later in the
afternoon/evening. Hail will be possible with a stronger storm or
two, with a few wind gusts reaching severe levels also possible —
especially if clustering can occur. In addition, a tornado cannot
be ruled out, given modest amounts of low-level veering/shear
expected. Some severe potential may linger into the overnight
hours, as continues to advance slowly southward.

…Southern AZ…
Relatively cool mid-level air will linger over Arizona, in
conjunction with the upper low lingering over northern portions of
the Gulf of California. In conjunction with diurnal
heating/destabilization, thunderstorm development is expected to
increase during the afternoon, with a few stronger storms possibly
evolving — aided by a belt of enhanced southerly mid-level flow on
the east side of the low. Along with some risk for marginal hail,
gusty outflow winds will be possible.

..Goss/Gleason.. 09/25/2019


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