487
ACUS48 KWNS 040848
SWOD48
SPC AC 040846

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0346 AM CDT Thu Sep 04 2025

Valid 071200Z - 121200Z

...DISCUSSION...
A seasonally cool and dry continental airmass will be in place
across much of the eastern US at the start of the forecast period,
resulting in low severe potential. By Monday/Day-5, the surface high
pressure responsible for this airmass will have begun to move east
allowing return flow to become established across the Plains. At the
same time, lee troughing in response to a western US longwave trough
will reinforce the return flow regime.

As the moisture is drawn northward into the Plains, steep lapse
rates will advect out into the Plains from the higher elevations to
the west. This combination of moistening low-levels and steep
midlevel lapse rates will support increasing buoyancy profiles
through the week.

Any subtle shortwave trough that ejects out of the western trough
and emerges into the central and northern Plains will have an
opportunity to tap into this moist, buoyant atmosphere. The result
would be at least some potential for thunderstorms, some of which
could be severe. However predictability of these kinds of subtle
features is too poor at these lead times to attempt to highlight
favored days or corridors, thus predictability remains too low for
unconditional probabilities.

..Marsh.. 09/04/2025