Valid 271200Z – 281200Z
…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
WEST/NORTH TX…OH/NORTHERN KY…EASTERN MN/NORTHERN WI/U.P OF MI…
…SUMMARY…
Isolated severe thunderstorms are possible across west and north
Texas, Ohio and northern Kentucky, and parts of eastern Minnesota,
northern Wisconsin, and the Upper Peninsula of Michigan this
afternoon into this evening. Locally damaging wind will be the
primary threat, with some hail also possible across Texas.
…Synopsis…
A seasonably strong upper trough is forecast to shift eastward from
the northern Plains/upper Midwest into the Great Lakes by Wednesday
morning. The primary surface low will move eastward across Ontario
through the day, as an attendant cold front moves through the Ohio
Valley/lower Great Lakes regions southwestward into the lower MS
Valley and southern Plains.
…Southern Plains/ArkLaTex…
Considerable uncertainty remains regarding the evolution of
convection early Tuesday morning, which will affect boundary
placement and potential redevelopment this afternoon. The outflow
reinforced cold front will likely move into portions of north TX
during the morning. Widely scattered redevelopment is possible near
or north of the boundary this afternoon and/or this evening. Steep
midlevel lapse rates will support moderate to locally strong
buoyancy, with effective shear expected to be marginally supportive
of organized convection. A conditional risk for localized severe
winds and perhaps some hail will be present across this region,
though confidence regarding the details remains low, and a more
aggressive southward push of the outflow/front during the morning
may tend to limit the potential for substantial redevelopment later
in the period.
…Upper Great Lakes Region…
Despite generally limited moisture and heating, cold midlevel
temperatures associated with the upper trough will support the
development of weak buoyancy from eastern MN eastward into the U.P.
of MI, with SBCAPE of 250-750 J/kg possible. Steepening low-level
lapse rates and moderate westerly flow in the lowest 3 km will
support a threat for locally damaging wind with low-topped
convection this afternoon into the early evening. Some hail will
also be possible, though with updraft depth/intensity expected to
remain rather limited, the severe hail risk appears too low at this
time for any probabilities.
…Ohio into northern KY…
A broken line of thunderstorms is expected to develop along the cold
front this afternoon across portions of OH/KY. While the strongest
midlevel flow will generally lag the cold front, it will still be
sufficient to support effective shear of 20-30 kt, resulting in some
potential for marginally organized convection. Localized damaging
wind will be the primary threat, from isolated wet microbursts
and/or outflow from weakly organized clusters.
..Dean/Wendt.. 08/27/2019
$$