066
ACUS03 KWNS 110731
SWODY3
SPC AC 110730

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0230 AM CDT Fri Sep 11 2026

Valid 131200Z - 141200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SUNDAY INTO
SUNDAY NIGHT ACROSS A CORRIDOR FROM WESTERN NEW ENGLAND THROUGH THE
UPPER OHIO VALLEY AND ANOTHER CORRIDOR FROM  NEAR AND SOUTHWEST OF
THE BLACK HILLS THROUGH PORTIONS OF THE MIDDLE MISSOURI VALLEY...

...SUMMARY...
Strong storms accompanied by at least some risk for severe weather
appears possible across parts of the Northeast into Ohio Valley, and
across parts of the north central Great Plains, Sunday into Sunday
night.

...Discussion...
An initially notable mid-level low inland of the Pacific Northwest
coast by 12Z Sunday is forecast to remain progressive through this
period, though it may slowly begin to devolve into an open trough
while accelerating across the northern U.S. Rockies in response to a
short wave digging into northwestern portions of the Canadian
Prairies.  Within the downstream westerlies, models indicate that
short wave ridging will build across the northern U.S. Great Plains
and adjacent Canadian Prairies through the Upper Midwest/adjacent
northwestern Ontario, while downstream troughing digs across Quebec
through the lower Great Lakes region.

The primary surface cyclone associated with eastern troughing is
forecast to migrate from northern Quebec into the Labrador Sea by
late Sunday night.  As it does, the trailing cold front probably
will advance southeast of the lower Great Lakes region by late
Sunday afternoon, before overspreading the northern Atlantic
Seaboard through upper Ohio Valley by the end of the period.
Westward through the Ohio and middle Mississippi Valleys into the
central Great Plains, it appears that this front may stall near or
just south of the stronger westerlies.

...Parts of western New England into the Ohio Valley...
Models vary concerning the degree of pre-frontal destabilization and
the extent to which this may coincide with strengthening of westerly
flow in the 700-500 mb layer, downstream of the digging short wave
trough.  However, particularly to the lee of the lower Great Lakes
toward the northern Mid Atlantic vicinity, it appears that forcing
for ascent will become increasingly conducive to at least scattered
thunderstorm development by or shortly after peak daytime heating.
As this occurs, developing storms will probably be accompanied by at
least some risk for damaging wind gusts before weakening Sunday
evening.

...North central Great Plains/Middle Missouri Valley vicinity...
The degree to which cool/stable boundary-layer air remains
entrenched across much of Nebraska into parts of northern Kansas, to
the south of the westerlies and beneath a remnant plume of warm
elevated mixed-layer air, remains unclear.  Between the cool
boundary layer, which may be relatively shallow, and the base of the
capping elevated mixed layer, it does appear that a seasonably moist
air mass retreating northward through the region will contribute to
moderate to large CAPE.

Although notable spread exists within/among the various model
output, there appears potential for at least isolated to widely
scattered strong to severe storm development in moistening
southeasterly low-level flow across and to the southwest of the
Black Hills vicinity by late Sunday afternoon, with the approach of
the short wave trough.  Subsequent development eastward into the
Great Plains remains more uncertain, but, by late Sunday night,
stronger storm development seems most likely to focus on the nose of
a strengthening southerly low-level jet, near the northeastern
periphery of the plume of elevated mixed-layer air, across/northeast
of the middle Missouri Valley.  This may be accompanied by at least
a risk for severe hail.

..Kerr.. 09/11/2026

$$