Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1129 AM CDT Sun Aug 30 2026
Valid 301630Z - 311200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING FROM SOUTHEAST MONTANA AND FAR NORTHEAST WYOMING INTO THE
CENTRAL DAKOTAS...
...SUMMARY...
Severe storms capable of damaging wind gusts are possible across
portions of the northern Plains this afternoon and evening.
...Northern High Plains into the northern Plains...
Recent satellite imagery shows a well-defined shortwave trough
moving eastward across southern Saskatchewan and western MT/eastern
ID. A belt of stronger westerly flow aloft likely exists within the
base of this trough from eastern ID into western WY. Recent
mesoanalysis estimates 50 to 60 kt at 500 mb, but its actual
magnitude is uncertain. Showers and isolated thunderstorms are
already ongoing downstream of this wave, and the general expectation
is for these showers and thunderstorms to persist as the wave moves
eastward, eventually encountering a notably more unstable airmass
downstream.
Current surface observations show mid 60s dewpoints into the western
Dakotas, with upper 50s/low 60s dewpoints farther west in eastern
MT. Afternoon high temperatures are expected range from the low to
mid 80s along the MT/ND border into the low 90s farther south into
southwest SD. Despite relatively poor pre-frontal mid-level lapse
rates, the resulting temperature/dewpoint combination will support
MLCAPE ranging from around 500-1000 J/kg across eastern MT and the
western Dakotas to closer to 2000 J/kg across the central Dakotas.
Some low-level stability may linger, but should be overcome by the
strong forcing, and the development of a line of strong to severe
storms is anticipated. Strong to severe gusts will be the primary
risk, with some instance of gusts from 65 to 80 mph possible.
Maximum storm intensity and highest severe coverage is currently
forecast to occur from the ND/SD/MT border intersection vicinity
eastward into south-central ND and north-central SD. Decreasing
buoyancy is expected from the central Dakotas eastward, with
gradually decreasing storm intensity expected as the line of storms
moves into this region this evening.
...Central High Plains...
Increased coverage and depth of the thunderstorms across UT indicate
the presence of secondary area of ascent south of the primary
shortwave trough, perhaps tied to a convectively augmented vorticity
maximum. Expectation is for this vorticity maximum to progress
eastward, persisting across the central Rockies before entering
deeply mixed boundary-layer in place over the central High Plains.
High-based storm character coupled with steep low-level lapse rates
will support the development of strong outflow, and gusts from 60 to
75 mph are possible.
...UT/Western CO...
Thunderstorms are already ongoing from eastern UT into western CO,
and deep-layer vertical shear is already strong enough to support
organization within any more persistent updrafts. A few instances of
hail and/or damaging gusts are possible with this activity.
Additionally, considerable low-level moisture will remain over UT
today, leading to another round of strong to isolated severe
thunderstorms this afternoon. Deep-layer shear will remain
sufficient for rotating storms capable of damaging wind gusts and
hail. This additional activity should also spread into western CO
before weakening this evening.
...Central/Southern AZ...
Ample low-level moisture remains in place across much of AZ, with
upper 50s dewpoints across northern AZ increasing into the mid 60s
across southern AZ. Another day of afternoon thunderstorms is
anticipated as this moist airmass destabilizes amid strong diurnal
heating. High-based storms coupled with moderate buoyancy and steep
low-level lapse rates could result in a few strong to severe gusts
across the region this afternoon and evening.
..Mosier/Moore.. 08/30/2026
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