207
ACUS01 KWNS 090517
SWODY1
SPC AC 090515

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1215 AM CDT Sun Aug 09 2026

Valid 091200Z - 101200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MIDWEST...AND PORTIONS OF THE DAKOTAS...

...SUMMARY...
Scattered damaging winds may occur today into this evening from
southern Minnesota and eastern Iowa eastward across parts of
northern Illinois, southern Wisconsin, southern Lower Michigan,
northwest Ohio, and northern Indiana. Damaging wind and hail is also
expected across portions of the Dakotas.

...IA/MN into the Midwest...

Convection is expected to be ongoing this morning across parts of
southern MN into eastern IA. This early day activity could pose a
risk for damaging gusts. This activity is likely to continue to
spread eastward across the Lake Michigan vicinity through the
afternoon on the nose a of modest low-level jet and along a surface
front oriented across southern WI and Lower MI. This activity could
intensify as is moves into a destabilizing airmass by midday.

Additional development is possible within the moisture rich warm
sector across northern IL/IN along the southern flank of ongoing
convection and/or outflow. Strong to extreme instability is
forecast, while vertically veering wind profiles support 30+ kt
effective shear magnitudes. Low-level SRH also will be enhanced
along the surface boundary. While damaging winds are expected to be
the primary hazard with convection, some risk for hail and a tornado
or two also will exist through evening. Depending on the evolution
of morning convection, it is possible higher probabilities will be
needed in subsequent outlooks.

...Dakotas and western NE...

A surface front is expected to develop southward across the central
Plains, becoming oriented across northern KS by tonight. Low-level
warm advection atop the boundary, and surface winds becoming
south/southeasterly with time will maintain 60s dewpoints across the
region. Within this post-frontal upslope regime, moderate
northwesterly flow aloft will persist. A modest south/southwesterly
low-level jet is also forecast to develop during the evening hours.
Low-level convergence within the warm advection regime and
increasing low-level jet may be sufficient for isolated to scattered
thunderstorm development. Supercell wind profiles and steep
low-level lapse rates will support initial storms capable of large
hail and damaging winds. If sufficient clusters/outflow
consolidation can occur, upscale growth during the late evening into
overnight hours is possible, with an increasing risk for swaths of
severe/damaging gusts.

...Southern Appalachians...

Scattered thunderstorm development is expected over higher terrain
within a seasonally moist and unstable airmass. Steepening low-level
lapse rates and high PW values may support locally strong gusts with
wet microbursts through early evening.

...AZ...

Modest easterly mid/upper flow will persist across the region on the
southern periphery of an upper high over the Four Corners. Another
day of hot conditions will promote steep lapse rates and modest
destabilization. As convection develops over higher terrain and
spread westward, strong outflow gusts may occur.

..Leitman/Moore.. 08/09/2026

$$