Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0747 AM CDT Mon Aug 10 2026
Valid 101300Z - 111200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE SOUTHERN
GREAT LAKES INTO THE MID-ATLANTIC STATES...PORTIONS OF THE UPPER
MIDWEST AND CENTRAL HIGH PLAINS...AND SOUTHERN ARIZONA...
...SUMMARY...
Thunderstorms with severe wind gusts will be possible this afternoon
and evening from northern Illinois eastward into Pennsylvania.
Severe gusts and hail will also be possible from parts of the
central and northern Plains into the Midwest, with scattered severe
storms over southern Arizona.
...Synopsis...
Another highly uncertain and complex forecast with mesoscale
convective dependencies apparent this forecast update. Water-vapor
imagery implies a belt of west-northwest mid to high-level flow
extending across the northern High Plains east through much of the
Midwest, and to the north of a flattened mid-level ridge extending
from the Four Corners to FL. Embedded within the flow, a
convectively augmented disturbance over the southern Great Lakes
will move east into PA by early this afternoon. Another minor
perturbation over southwest MT this morning will quickly move into
the Dakotas by early evening and probably influence the severe
threat from SD into adjacent parts of IA/MN overnight.
...IL to the Mid-Atlantic...
Radar mosaic this morning shows an organized line segment moving
east along the OH-Lake Erie shoreline and a couple of other
thunderstorm clusters over western OH and south-central PA. The
Detroit, MI WSR-88D VAD showed a mid-level speed max associated with
the convectively augmented vorticity max moving east across the Lake
Erie vicinity. Gradual intensification of storms is expected this
morning as the boundary layer heats downstream across OH into PA and
the Mid-Atlantic states (refer to MCD 1892 for short-term details
regarding the northeast OH thunderstorms). Of particular note, the
12 UTC Pittsburgh, PA and Wilmington, OH raobs showed a moderate to
very unstable airmass (1800-2700 J/kg MLCAPE, respectively) in place
over the upper OH Valley. Severe gusts capable of scattered wind
damage will be possible through the afternoon with any stronger
thunderstorms and clusters of storms. Farther west, models show
storm redevelopment perhaps centered over northern IN/IL later this
afternoon/evening. Shear/buoyancy profiles will support organized
storms, including supercells and linear clusters. Damaging wind and
hail will be the primary hazards, though a tornado or two also could
occur.
...Dakotas into MN/IA...
Similar to previous forecast thinking, southeasterly low-level flow
will aid in the transport of seasonably rich moisture (mainly 60s F
surface dewpoints) north and west into SD. Model forecast soundings
show large buoyancy developing by mid afternoon within the
aforementioned moist plume. The weak impulse implied by model
guidance moving into western SD may enable at least isolated to
potentially scattered storms developing towards early evening over
western and central SD. The 00z ECMWF and 00z HREF consensus
suggest a linear cluster evolves during the evening and grows
upscale into an MCS during the overnight moving east-southeast along
a residual frontal zone. Have included an intensity level-1 to
denote this conditional but significant wind risk if this forecast
scenario occurs.
...AZ...
Mid/upper easterly flow will persist today amid plentiful moisture
and strong heating. This will support thunderstorm development once
again across higher terrain. Scattered storms are forecast to
eventually develop with their cold pools coalescing over the lower
desert. Based on the latest CAM guidance and inverted-V profiles
with marginally supportive shear for loose storm organization, have
upgraded a part of the lower desert into higher severe-wind
probabilities. Widely scattered to scattered severe gusts 60-75 mph
are possible with this activity.
...NE/CO/KS...
Scattered thunderstorms are expected to develop near a surface
trough across western NE/northeast CO by late afternoon/early
evening. As the high-based storms mature into possibly a small
linear cluster and move into richer moisture with east extent, steep
low- to mid-level lapse rates will support severe gusts (60-75 mph)
and perhaps hail with this activity.
..Smith/Kerr.. 08/10/2026
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