LIVE MAP (ABOVE) ... SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0802 PM CDT Sat Jul 26 2025
Valid 270100Z - 271200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTH-CENTRAL U.S....
...SUMMARY...
Severe thunderstorms with damaging wind gusts and hail will be
possible this evening into tonight across parts of the northern
Plains from eastern Montana into the Dakotas and southward to
Nebraska. Isolated damaging wind gusts will also be possible this
evening from parts of the mid Mississippi Valley eastward into the
Mid-Atlantic.
...Central and Northern Plains/Northern Rockies...
At mid-levels, a ridge will remain located over the northern Plains
this evening, as a shortwave trough approaches from the southwest.
The shortwave is moving northeastward across the central and
northern Rockies, which is evident on water vapor imagery. Ahead of
this feature, large-scale ascent will overspread a moist airmass
located across the central and northern Plains. Surface dewpoints
within this airmass are mostly from the mid 60s to mid 70s F. This
is contributing to a large pocket of strong instability across the
Dakotas, where MLCAPE is estimated to be in the 3500 to 5500 J/kg
range, according to RAP analysis data. Moderate instability extends
southward into the central Plains. Along the western edge of the
stronger instability, a broken line of thunderstorms is ongoing from
central South Dakota southward into western Nebraska.
Moderate deep-layer shear is analyzed by the RAP over much central
and northern Plains. The stronger flow is a result of upper-level
jets located over far southern Canada and central Nebraska. RAP
forecast soundings from western Nebraska northward into the central
Dakotas generally show 0-6 km shear in the 30 to 40 knot range, with
directional shear located in the low to mid-levels. This will be
favorable for supercell development this evening, mainly with cells
that remain semi-discrete. Supercells will likely have an isolated
large hail threat, mainly from central South Dakota into southern
and eastern North Dakota, where the strongest instability is
located. Hailstones greater than 2 inches in diameter will be
possible. In addition, organized line segments with wind-damage
potential are expected.
Further west into parts of the northern High Plains, scattered
thunderstorms are ongoing across central and northeast Montana. As
the shortwave trough moves across the region this evening,
convective coverage is expected to gradually increase. A severe
threat will be possible along an near an axis of moderate
instability, which the RAP currently shows from northwestern North
Dakota into north-central Montana. Very steep low to mid-level lapse
rates would be favorable for damaging wind gusts with the stronger
storms.
....Mid Mississippi and Ohio Valleys/Central
Appalachians/Mid-Atlantic...
A mid-level trough is currently evident on water vapor imagery over
the central and southern Great Lakes. Scattered thunderstorms are
ongoing along the southern edge of this feature from the mid
Mississippi Valley eastward into the central Appalachians. Along
this east-to-west corridor, surface dewpoints are from the 70s into
the lower 80s F. This is contributing to moderate instability, which
is present over most of the region. The unstable environment should
support a marginal wind-damage threat associated with the stronger
multicells this evening.
..Broyles.. 07/27/2025
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