Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0752 PM CDT Mon Aug 31 2026
Valid 010100Z - 011200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
THE GREAT BASIN...THE CENTRAL PLAINS...AND THE MIDWEST/GREAT
LAKES...
...SUMMARY...
Isolated strong to severe thunderstorms remain possible into tonight
across parts of the Upper Midwest/Great Lakes into western New York,
the central Plains, and lower Colorado River Valley into the Great
Basin. Severe hail and strong/damaging winds should be the main
threats.
...Great Lakes to western NY...
Evening water-vapor imagery showed an occluded upper low over MB/AB
moving eastward with a low-amplitude shortwave trough over the
central Plains. A corridor of enhanced mid-level westerly flow was
overspreading the Midwest and western Great Lakes. At the surface, a
weak cold front was moving from southern Canada into western WI and
trailing westward across the central Plains.
A rather moist and strongly unstable air mass remains in place this
evening across portions of WI/MI ahead of the surface front. So far,
weak forcing for ascent and residual inhibition has prevent much in
the way of robust convection. Isolated development will remain
possible, as hinted by short term guidance, through later this
evening given the strong instability and glancing influence of the
upper low/trough. While uncertain, if storms are able to develop,
45-50 kt of bulk shear would support supercells with damaging wind
and some hail potential across eastern WI into lower MI.
Thunderstorms may also spread from Lower MI and southern ON into
western NY tonight into early Tuesday morning aided by low-level
warm air advection. Increasing instability may support an isolated
threat for damaging winds overnight.
...Central Plains...
High-based thunderstorms ongoing across the High Plains of CO will
continue to track northeastward along the surface front this
evening. Hot surface temperatures have helped steepen low/mid-level
lapse rates and will support isolated strong to severe downdraft
winds with this activity. Occasional hail may also occur with the
strongest cores thanks to some organization from a belt of stronger
mid-level flow. This organization and coalescing outflow could
support some clustering later tonight. See MCD#2138 for additional
information.
...Great Basin...
Scattered thunderstorms are ongoing this evening over portions of
southern UT/NV. Aided by strong heating of a monsoon air mass and
weak ascent from a passing shortwave trough, these storms should
continue into the overnight hours. Modestly enhanced mid-level flow
and steep low-level lapse rates will support severe wind potential
and some risk for hail with the stronger clusters or transient
supercells. Much weaker buoyancy to the north may limit severity of
the convection as they encounter the more stable air mass this
evening.
...Coastal/Southeast Texas into Southern Louisiana...
Reference NHC forecasts/advisories for the latest information on TD
5. Low-level easterly flow on the northern side of the TC
should remain modest ahead of a forecast landfall tomorrow. This,
combined with the compact nature of the system favors weak low-level
shear and limited potential for onshore bands with tornado or
thunderstorm driven damaging wind potential.
..Lyons.. 09/01/2026
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