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

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1259 AM CDT Mon Aug 10 2026

Valid 111200Z - 121200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE OHIO VALLEY AND CENTRAL APPALACHIANS...

...SUMMARY...
Severe thunderstorms with damaging wind gusts will be possible on
Tuesday from parts of the Ohio Valley into the central Appalachians
in the afternoon and evening. Isolated severe wind gusts and hail
will also be possible from parts of the central and northern Plains
into the Midwest.

...Ohio Valley/Central Appalachians...
At mid-levels, west-northwesterly flow will remain in place on
Tuesday from the northern Plains to the central Appalachians. At the
surface, a quasi-stationary front is forecast to be located from
northern Illinois east-southeastward into far northern Kentucky. To
the south of the front, surface dewpoints in the lower to mid 70s F
will result in moderate to strong instability by midday. Low-level
convergence along the boundary will likely be the focus for
convective initiation during the day. It appears that an intense
line segment could develop and move east-southeastward along and
near the frontal zone from mid afternoon to mid evening. However,
there is some uncertainty concerning where the boundary from morning
convection will be in the afternoon.

Forecast soundings along and to the south of the front from
east-central Illinois into far northern Kentucky at 21Z have MLCAPE
in the 2000 to 3500 J/kg range. Wind profiles along this
west-northwest to east-southeast corridor have directional shear in
the boundary layer with 40 to 50 knots of west-northwesterly flow in
the mid-levels. Some of this zone could have 0-6 km shear in the 40
to 50 knot range along with 0-3 km storm-relative helicity around
200 m2/s2. This would support supercells with severe wind gusts and
an isolated tornado threat. Some model forecasts, including the HRRR
suggest that an organized cold pool will develop during the late
afternoon. This scenario could result in a swath of wind damage
across parts of the Ohio Valley.

...Central and Northern Plains/Midwest...
At mid-levels, rising heights and west-northwesterly flow will be in
place over the north-central U.S. on Tuesday. At the surface, a cold
front will move southeastward across the northern High Plains, as a
low deepens across South Dakota. Ahead of the front, surface
dewpoints in the 60s and 70s F will contribute to moderate to strong
instability by afternoon. Low-level convergence will aid convective
initiation during the mid to late afternoon, with isolated storms
moving east-southeastward from the northern Plains into the Midwest.

Across the moist airmass, MLCAPE is forecast to peak in the 2000 to
3000 J/kg range with 0-6 km shear in the 35 to 45 knot range. This
will support supercells with isolated severe wind gusts and hail.
However, the rising mid-level heights and lack of large-scale ascent
could result in a more localized severe threat.

..Broyles.. 08/10/2026

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0230 AM CDT Mon Aug 10 2026

Valid 121200Z - 131200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL AND NORTHERN HIGH PLAINS...

...SUMMARY...
Thunderstorms with severe wind gusts and hail will be possible
Wednesday afternoon and evening across parts of the central and
northern High Plains. Isolated severe wind gusts will also be
possible from parts of the mid Missouri Valley east-southeastward
into the southern Appalachians.

...Central and Northern Plains...
West-northwesterly mid-level flow will be in place on Wednesday from
the northern Plains into the Great Lakes. Within the flow, a subtle
shortwave trough is forecast to move into the central and northern
High plains during the afternoon. At the surface, a cold front is
forecast to move southward in the central Plains, with a lee trough
located in the High Plains. During the day, upslope flow will help
low-level convergence to become maximized along the lee trough,
which will the primary focus for convective initiation Wednesday
afternoon. Thunderstorms are expected to form near the trough and
move eastward across the central and northern High Plains during the
late afternoon and early evening.

Along the western edge of the moist airmass, surface dewpoints are
forecast to be mostly in the 60s F, which should result in moderate
instability by afternoon. Late afternoon forecast soundings from
North Platte, Nebraska northward to east of Rapid City, South Dakota
have 0-6 km shear in the 35 to 45 knot range with low to mid-level
lapse rates near 8 C/km. This will support a supercell threat during
the late afternoon and early evening. Supercells will be capable of
severe wind gusts and isolated large hail.

...Mid Missouri and Mid Mississippi Valley/Ohio Valley/Southern
Appalachians...
Mid-level northwesterly flow will be in place on Wednesday from the
Mid Missouri Valley into the Ohio Valley. At the surface, a very
moist airmass will also be in place over this same area. Surface
dewpoints in the 70s F will contribute to moderate to strong
instability by afternoon. Isolated to scattered thunderstorms will
be possible near outflow boundaries as low-level convergence becomes
maximized in the afternoon. Across much of this moist and unstable
airmass, moderate deep-layer shear will be in place supporting an
isolated wind-damage threat. The wind-damage threat should be
greatest in the late afternoon and early evening as low-level lapse
rates become steep.

..Broyles.. 08/10/2026