694
ACUS02 KWNS 040602
SWODY2
SPC AC 040600

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Thu Sep 04 2025

Valid 051200Z - 061200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS STRETCHING FROM
NORTHERN TEXAS NORTHEAST INTO SOUTHERN OHIO...

...SUMMARY...
Strong thunderstorms will be possible from the southern Plains into
the Ohio and Tennessee Valleys during the afternoon into the
overnight hours. Isolated large hail and damaging winds may be
possible with the strongest storms.

... Synopsis ...

A seasonably strong/cold midlevel low will persist across Ontario,
with an attendant larger-scale trough persisting across much of the
eastern United States. A potent midlevel shortwave trough will be
across the Upper Great Lakes at the start of the period and will
quickly rotate around the upper low into Quebec through the period.
In its wake a midlevel ribbon of higher vorticity will be left
behind from Iowa northeast across Michigan.  Upstream from this, the
midlevel height field will begin to respond to another shortwave
trough rotating around the Ontario low.

At the surface, a surface low will quickly lift northeast from
northern Michigan through Ontario and into Quebec through the
forecast period. A cold from will extend southwest from this low and
will push south and east as the surface low lifts northeast.
Although somewhat diffuse initially, the temperature gradient across
the cold front will rapidly strengthen through the day.

... Ohio and Tennessee Valleys ...

Diurnal heating should allow afternoon temperatures to warm into the
80Fs and 90Fs across the region. Given surface dewpoint temperatures
in the mid 60Fs perhaps as far north as southern Ohio, this heating
will result in most-unstable CAPE values in excess of 2000 J/kg
across the area. The region will also be on the periphery of the
stronger midlevel flow, yield effective shear of around 40 knots.

Thunderstorms should develop by late afternoon in response to
increasing large-scale ascent associated with both differential
vorticity advection and frontal circulations. Given the degree of
instability and effective layer shear, initial thunderstorms may
exhibit supercellular structures. However, given the
temperature-dewpoint spreads on the order of 20F+ the expectation is
that thunderstorms should tend to favor upscale growth toward linear
segments. As such, thunderstorms may initially pose a hail threat,
especially across western Kentucky and Tennessee, but should
transition to more of a wind threat with eastward extent.

Across portions of Kentucky and southern Ohio, a short-window,
conditional tornado threat may evolve as thunderstorms develop in
the vicinity of the surface boundary. As thunderstorms interact with
or cross over the boundary, strong northeasterly surface winds will
enlarge low-level hodographs supporting at least some tornado
threat.

... Greater Arklatex Region ...

The surface cold front across the region is expected to strengthen
during the day as it slowly moves south. During the evening into the
overnight hours, strong warm-air advection on the nose of a
strengthening low-level jet may support thunderstorm development on
the cool side of the cold front. Despite surface temperatures in the
60Fs and low 70Fs, steep mid-level lapse rates atop the colder
surface layer may support isolated large hail.

..Marsh.. 09/04/2025

$$