Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0734 AM CDT Sat Jul 05 2025
Valid 051300Z - 061200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR SOUTHEAST
MONTANA INTO FAR NORTHEAST WYOMING AND EXTREME NORTHWEST SOUTH
DAKOTA...
...SUMMARY...
Scattered severe storms are likely across portions of the northern
High Plains this afternoon through the evening. Severe gusts
ranging from 60-85 mph and large to very large hail are the primary
hazards.
...Northern High Plains...
Water-vapor imagery this morning shows a mid-level trough over the
Pacific Northwest/northern Rockies. A belt of 40-50 kt 500-mb flow
will move east from ID across southern MT and northern WY through
the late evening. In the low levels, surface low pressure will
develop over central WY today to the south of a high centered over
SK/MB, aiding in maintaining an easterly component to low-level flow
across southern MT. The northern periphery of steep 700-500 mb
lapse rates will be atop a destabilizing boundary layer and will
contribute to moderate buoyancy. As large-scale ascent overspreads
south-central MT by early to mid afternoon coincident with eroding
convective inhibition, isolated to scattered thunderstorms are
forecast to develop. Ample deep-layer flow will favor a few
supercells with the early activity as storms mature/organize. An
eastward-moving cluster is forecast to evolve (supported by recent
CAM guidance) during the early evening, with a potential swath of
severe gusts focused over southeast MT into adjacent parts of WY/SD.
As storms move farther east, less buoyancy will tend to limit the
severe risk with east extent into parts of the Dakotas.
...Central-Southern High Plains...
Scattered thunderstorm development is expected this afternoon into
the evening in the vicinity of a lee trough over the central High
Plains and farther south closer to the Raton Mesa. A relatively
moist and moderately unstable airmass (~1000-2500 J/kg MLCAPE) will
support vigorous updrafts mainly in the form of multicells and small
clusters. This activity will likely spread east-southeastward into
the evening hours. Severe gusts and perhaps large hail may accompany
the more intense storms.
...Upper Midwest into the central Plains...
A separate midlevel trough will move eastward across the Upper
Midwest, while a related cold front advances southeastward across
the Upper Midwest and Lower MO Valley during the day. Despite poor
midlevel lapse rates, rich boundary-layer moisture and a belt of
enhanced low/midlevel flow will support a few strong to severe
storms capable of damaging gusts along/ahead of the front.
...Carolina coast...
The low-level wind profile is forecast to gradually strengthen
concurrent with the approach of Tropical Storm Chantal (see the
National Hurricane Center for the latest details regarding Chantal's
forecast track). By the evening, hodographs begin to substantially
enlarge near the coast and the influx of richer low-level moisture
(mid 70s F surface dewpoints) are expected to infiltrate the
immediate coast. As such, a few transient supercells are possible
with an accompanying low risk for a tornado---mainly during the
overnight.
..Smith/Broyles.. 07/05/2025
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