572
ACUS03 KWNS 130705
SWODY3
SPC AC 130704

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0204 AM CDT Sun Sep 13 2026

Valid 151200Z - 161200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TUESDAY
AFTERNOON INTO EVENING IN A CORRIDOR SOUTH/SOUTHWEST OF THE GREAT
LAKES THROUGH THE LOWER MISSOURI VALLEY...

...SUMMARY...
Scattered strong thunderstorms may impact a corridor south to
southwest of the Great Lakes through the lower Missouri Valley
Tuesday afternoon and evening, accompanied by at least some risk for
locally damaging wind gusts.

...Discussion...
A deamplifying mid-level short wave trough and associated surface
cyclone are forecast to continue an east-northeastward migration
through this period, generally across the remainder of northwestern
Ontario through much of northern Quebec by late Tuesday night.  In
the wake of the cyclone, an initial low-level baroclinic zone across
the lower Great Lakes region through the lower Missouri Valley and
central Great Plains may make some southward progression, before
stalling and perhaps retreating northward beneath the building
northwestern periphery of prominent ridging still centered across
the Southeast.  There is variance among the guidance concerning this
latter development, and the evolution of digging upstream mid-level
troughing across the northern Intermountain Region and Pacific
Coast.

...Southern Great Lakes through central Great Plains...
Mainly where mid-level heights remain suppressed, prior to the onset
of the mid-level height rises, coincident with daytime
boundary-layer destabilization along and southeast of the slow
moving frontal zone, a corridor of increasing, scattered
thunderstorm development appears possible through mid to late
Tuesday afternoon.  Steepening low-level lapse rates may support the
evolution of moderate mixed-layer CAPE on the order of 1000-2000+
J/kg, near the modest southern fringe of the mid-level westerlies,
which may still include speeds of 30+ kts in the 700-500 mb layer.
A warm layer in mid/upper levels may tend to suppress large hail,
but thermodynamic profiles characterized by steep lapse rates of
potential wet-bulb temperatures in lower/mid-levels could contribute
to a few downbursts and developing cold pools with a few strong
gusts into Tuesday evening.

..Kerr.. 09/13/2026

$$