Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1225 AM CDT Mon Aug 10 2026
Valid 101200Z - 111200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTION OF
THE MIDWEST INTO PA AND NORTHERN MD/VA...AND ACROSS PARTS OF THE
NORTHERN PLAINS...
...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 strong
storms over southern Arizona.
...Synopsis...
A belt of enhanced west/northwesterly flow aloft will overspread the
northern Plains to the Midwest and southern New England
today/tonight. Only modest height falls are forecast at best.
However, several convectively enhanced vorticity maxima are forecast
to migrate through this upper flow regime, focusing several areas of
severe storm potential today into tonight from the northern Plains
to the upper Ohio Valley and parts of the Mid-Atlantic.
...IL to the Mid-Atlantic...
Early day thunderstorms may move across parts of the Midwest this
morning, but should generally be sub-severe. By midday, convection
could intensify within a couple of corridors. The first being the
upper Ohio Valley/PA/western NY. Thunderstorm clusters will pose a
risk for damaging winds and hail within a moderately unstable
airmass as convection spreads east toward the Mid-Atlantic.
Additional thunderstorm development is expected later in the
afternoon associated with another shortwave impulse spreading east
from IL into IN/OH. This activity will develop within strong
instability and rich boundary layer moisture. Modestly steep
midlevel lapse rates and effective shear greater than 40 kt will
support initial supercells. With time, sufficient clustering is
expected and bowing segments will be possible. Damaging wind and
hail will be the primary hazards, though a tornado or two also could
occur.
...Dakotas into Iowa...
Southeasterly low-level flow will transport mid/upper 60s dewpoints
north and west across SD, with 70s dewpoints common with southeast
extent across NE/IA/southern MN. This will support a corridor of
strong to extreme instability across the region. While coverage
remains uncertain, most guidance develops at least isolated
thunderstorms by evening. Elongated hodographs amid favorable deep
shear will support supercells and bows capable of large hail and
damaging winds. With time, it is possible sufficient clustering
occurs and upscale growth into a bowing MCS is possible as a
low-level jet develops overnight. If this occurs, a swath of
damaging winds is possible across parts of SD into northwest IA,
oriented along the stronger instability gradient.
...NE/CO/KS...
Scattered thunderstorms are expected to develop near a surface
trough across western NE/northeast CO by late afternoon/early
evening. This activity will spread east/southeast. Steep low-level
lapse rates will support strong outflow gusts and perhaps hail with
this activity.
...AZ...
Mid/upper easterly flow will persist today amid plentiful moisture
and strong heating. This will support thunderstorm development once
again across higher terrain. As storms propagate westward off the
higher terrain, isolated severe gusts will be possible.
..Leitman/Moore.. 08/10/2026
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