Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0256 PM CDT Tue Aug 26 2025
Valid 262000Z - 271200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Organized severe thunderstorms appear unlikely across the contiguous
United States through tonight.
...20Z Update...
Isolated strong storms remain possible in the Four Corners vicinity
this afternoon. Observed 18Z soundings from Tucson and Flagstaff
indicate relatively poor mid-level lapse rates and marginal
effective shear. Areas of stronger surface heating could promote
stronger outflow winds, but organized severe storms are still
unlikely. Only minor modifications were made to the general thunder
area based on current observations. Additional forecast details are
in the previous discussion below.
..Wendt.. 08/26/2025
.PREV DISCUSSION... /ISSUED 1120 AM CDT Tue Aug 26 2025/
...Synopsis and Discussion...
Large-scale upper troughing will remain over the eastern CONUS
today, with surface high pressure dominating much of the
central/eastern CONUS. Isolated thunderstorms may occur this
afternoon and evening along/south of a surface cold front across
parts of the FL Peninsula and central/south TX. However, weak flow
aloft and related deep-layer shear should preclude an organized
severe threat across these regions with this activity.
Scattered to numerous thunderstorms are expected to develop today
across much of the interior western CONUS, as upper ridging weakens
over the Southwest and multiple weak mid-level perturbations move
north-northeastward across the Sierras and Great Basin. Ongoing
thunderstorms this morning across the Central Valley in CA will be
in a relatively more favorable thermodynamic environment, with
modestly steepened mid-level lapse rates compared to locations
farther east over the Great Basin potentially supporting small hail
with the stronger cores. Still, shear is expected to remain modest
at best with westward extent, which should limit updraft
organization and overall severe potential.
Isolated strong/gusty winds may also occur with any convection that
can develop over parts of interior southern CA into the lower CO
River Valley, particularly where steepened low-level lapse rates can
develop with daytime heating/mixing of the boundary layer away from
ongoing cloud cover. The potential for a more concentrated corridor
of severe winds still appears low across this area, as it will be in
a generally subsident regime behind a weak mid-level shortwave
trough advancing northward from southern NV across the Great Basin
this afternoon.
Finally, an occasional/very isolated strong to severe gust cannot be
ruled out across the Four Corners region this afternoon, as
convection develops along the Mogollon Rim in northern AZ and
subsequently spreads north-northeastward in tandem with a weak
mid-level shortwave trough. Even so, deep-layer shear appears too
marginal to include low severe wind probabilities with this update.
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