Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1258 AM CDT Sun Oct 10 2021
Valid 111200Z - 121200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE MID
MISSISSIPPI/LOWER OHIO VALLEYS NORTHWARD INTO THE UPPER GREAT
LAKES...
...SUMMARY...
Strong/isolated severe storms -- including potential for hail,
locally damaging winds, and a couple of tornadoes -- are expected to
spread from the Mid Mississippi Valley region early,
north-northeastward into the Upper Great Lakes through the
evening/overnight hours Monday and into early Tuesday.
...Synopsis...
An upper trough digging south-southeastward across California and
the Great Basin Monday will evolve into a closed low, which is
expected deepen and turn eastward overnight reaching the
southwestern Utah vicinity Tuesday morning. Ahead of this system, a
negatively tilted short-wave trough will be shifting northeastward
across the Lower Missouri and Mid Mississippi Valleys during the
day, before crossing the Upper Great Lakes region overnight.
Meanwhile, ridging will remain in place -- aligned roughly along the
Appalachians.
At the surface, a cold front associated with the western U.S. trough
will sweep across the Great Basin and into the Four Corners states.
Meanwhile, a cold front shifting eastward out of the southern Plains
toward the Mississippi Valley will weaken with time, while an
associated/weak frontal low advances northeastward from Missouri to
Wisconsin/Upper Michigan through the period.
...Mid Mississippi Valley northward into the Upper Great Lakes...
Showers and scattered thunderstorms will likely be ongoing at the
start of the period from western Illinois/Missouri
south-southwestward to southeastern Texas, ahead of an advancing
cold front. A couple of stronger storms ongoing early could pose
local risk for severe weather. After a few hours of local/limited
risk, diurnal heating through late morning and into the afternoon
will permit sufficient destabilization to allow gradual
reintensification/redevelopment of storms, from Illinois to the
Mississippi Delta region, then spreading northward and northeastward
through the afternoon. Though flow aloft will remain largely
south-southwesterly/unidirectional, sufficient speed shear combined
with weak veering through the lowest 1 km or so suggests that
locally severe/rotating storms will evolve, with threat for damaging
wind gusts, along with some hail risk and potential for a couple of
tornadoes across a relatively broad geographic region.
A bit more uncertainty exists with northward extent, and into the
evening hours, into the Great Lakes region. While ascent will
spread across this region supporting a continuation of convection
through the evening and into the overnight hours, less substantial
instability -- diminishing further in tandem with diurnal cooling --
suggests that severe risk will wane gradually from late evening
onward.
..Goss.. 10/10/2021
