SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0750 AM CDT Thu Aug 07 2025
Valid 071300Z - 081200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
NORTH DAKOTA...
...SUMMARY...
Scattered severe thunderstorms are expected later today into tonight
across the northern Plains. The most likely corridor is centered on
North Dakota, where a few tornadoes, very large hail, and
significant severe gusts are possible.
...Northern Plains...
Elevated thunderstorms are ongoing across northeastern MT this
morning, supported by warm-air advection throughout the northwestern
periphery of surface low over southeast MT. Steep mid-level lapse
rates remain in place downstream of these storms, and southwesterly
mid-level flow will persist, so the general expectation is for these
storms to continue through the morning into the early afternoon.
Cloud cover associated with these storms could result in a
differential heating zone that with create a warm-front-like feature
across northern ND. At the same time, moisture low-level
southeasterly flow will continue across the northern Plains, with
dewpoints likely in the upper 60s/low 70s across much of the region
by the early afternoon.
The surface low over southeast MT is forecast to drift eastward this
morning towards the MT/WY/SD border intersection vicinity. To the
north of this low, the combination of low-level moisture convergence
and strengthening large-scale ascent will likely result in
convective initiation by the early afternoon. Surface dewpoints in
the upper 60s/low 70s and surface temperatures in the 80s beneath
steep mid-level lapse rates will result in an impressive
thermodynamic environment from the MT/ND border downstream into more
of ND. Most guidance suggests MLCAPE from 3000 to 4000 J/kg.
Moderate shear is also expected within this initiation zone,
supporting an initially supercellular storm mode. All severe hazards
would be possible with these supercells, including very large hail
exceeding 2" in diameter, significant severe gusts around 75 mph,
and tornadoes. Clustering and upscale growth appears probable, with
the resulting MCS then tracking eastward across ND.
Given the extreme buoyancy and moderate westerly flow aloft, there
is some potential for the development of a robust rear inflow jet
and resulting MCS that could be qualified as a derecho. However,
confidence in the development of derecho is too low to increase wind
probabilities with this outlook. Regardless, significant wind gusts
appear possible, particularly if the previously mentioned
warm-front-like feature develops and acts as a favored corridor for
MCS propagation. Low-level southeasterly flow is also expected to be
strong enough for some potential for line-embedded tornadoes.
Additional elevated thunderstorms are possible in the wake of this
MCS amid modest warm-air advection atop the MCS outflow. Some large
hail is possible within these storms.
...Northern High Plains...
Farther west, isolated to widely scattered supercells may develop
within a moderately unstable post-frontal regime from central into
eastern MT. Elongated hodographs and steep lapse rates will support
severe hail and wind potential with these cells. Some clustering
remains possible within this regime as well, and depending on the
evolution of downstream convection, storms that initiate in MT may
eventually spread into western/central ND late tonight with a
continued severe threat.
...Northern MO/IA into the Upper Midwest...
Elevated thunderstorms are currently ongoing across southern IA and
northern MO, supported by warm-air advection resulting from a
low-level jet that extends from the TX Panhandle through eastern KS.
Steep mid-level lapse rates are present across much of the region
(sampled by the 12Z TOP sounding), and these storms will likely
continue through the afternoon. An isolated strong wind gusts is
possible with these storms.
Additional thunderstorms are possible later this evening farther
northeast in central/southern WI and northern IL as the low-level
jet strengthens again. Deep-layer flow will be relatively modest,
but rich moisture and moderate to strong buoyancy will support a
threat for at least isolated hail and damaging wind.
..Mosier/Bentley.. 08/07/2025
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