Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1242 AM CDT Sun Aug 09 2026

Valid 101200Z - 111200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN GREAT LAKES...

...SUMMARY...
Thunderstorms with severe wind gusts will be possible Monday
afternoon and evening from northern Illinois eastward into western
Pennsylvania. Isolated severe gusts and hail will also be possible
from parts of the central and northern Plains into the Midwest.

...Southern Great Lakes...
At mid-levels, west-northwesterly flow will be in place on Monday
from the northern Plains into the Great Lakes. A subtle mid-level
shortwave trough and an associated jet streak will move through the
Great Lakes. To the south of the jet streak, a cold front is
forecast to advance southward into northern Illinois, northern
Indiana and northern Ohio by mid afternoon. Low-level convergence
along the front will be a focus for convective development. To the
south of the front, surface dewpoints in the 70s F will contribute
to moderate to strong destabilization by afternoon, with MLCAPE
likely peaking in the 2000 to 3500 J/kg range. Thunderstorms are
expected to develop near the front and move east-southeastward into
the stronger instability during the afternoon and evening.

Along the instability axis in the late afternoon from Lincoln,
Illinois to Pittsburgh, Pennsylvania, the ECMWF has 0-6 km shear
around 30 knots. This should support a mixed mode, with short
intense line segments and embedded rotating storms possible. The
primary threat will damaging wind gusts, with the maximum threat
located ahead of any cold pool that can organize. The severe threat
could persist into the early to mid evening, especially if MCS
development takes place, maintained by increasing low-level flow.

...Central and Northern Plains/Midwest...
West-northwesterly mid-level flow will be in place over the
north-central U.S. on Monday. A subtle shortwave trough is forecast
to move east-southeastward across the northern Plains. At the
surface, a cold front is forecast to advance southward across
western South Dakota during the day, with a dryline extending
southward into western Nebraska. To the east of the dryline, surface
dewpoints in the 60s and 70s F will contribute to moderate to strong
instability by afternoon. Isolated thunderstorms appear likely to
develop near the dryline during the mid to late afternoon.
Additional isolated storms are expected to develop further east
along the moist axis from eastern Nebraska into Iowa.

Forecast sounding along the moist axis in the late afternoon have
MLCAPE peaking in the 3000 to 4000 J/kg range with 0-6 km shear
around 30 knots. This environment, combined with steep low to
mid-level lapse rates, will support isolated potential for severe
wind gusts and hail.

..Broyles.. 08/09/2026