845
FNUS28 KWNS 212128
FWDD38

Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0426 PM CDT Thu Aug 21 2025

Valid 231200Z - 291200Z

Upper-level ridging will continue over much of the West this weekend
but will begin to weaken Day 4/Sunday - Day 5/Monday. The upper high
is likely to retreat towards Texas, with weak ridging maintaining
over portions of the West early to mid-next week. Weak flow overall
is likely over the West, while weak troughing may develop off the
West Coast and possibly into the Northwest next week. Monsoonal
moisture will stream north through the Great Basin and into the
Northwest and northern Rockies, but a backdoor cold front and
weakening ridging may limit monsoonal moisture in the northern
Rockies.

Isolated to scattered mixed wet/dry thunderstorms are likely in the
northern Sierra into the southern Cascades and across the northwest
Great Basin on Day 3/Saturday, with another round slightly farther
north on Day 4/Sunday. A few concerns regarding dry thunderstorm
potential are the expected cloud cover with the monsoonal moisture
moving northward limiting instability, potential training of
storms/deeper moisture leading to more wetting rain, and fuels still
rebounding from recent rainfall. However, given the hot, dry,
unstable, and locally breezy conditions ahead of and coincident with
the initial monsoonal surge, fuels will cure rapidly and cloud bases
and storm motions could be  high and fast enough, respectively, to
result in at least isolated dry thunderstorm coverage in portions of
Oregon, northern California, and northern Nevada. Beyond Day
4/Sunday, there is too much uncertainty regarding dry thunderstorm
potential to include probabilities at this time in the Northwest,
northern California, northern Great Basin, and northern Rockies.

Daily scattered to widespread mostly wet thunderstorms are expected
across much of the southern/central Great Basin, Colorado Rockies,
Southwest, and eastern California. This will significantly slow fire
season for these areas and possibly provide season ending rain for
some areas.

Well above normal temperatures and prolonged low RH are expected
across northern California, the Northwest, northern Great Basin, and
northern Rockies Day 3/Saturday, with portions of northern
California and the northern Great Basin seeing higher RH and
slightly lower temperatures on Day 4/Sunday due to the monsoonal
moisture. Above normal temperatures will continue much of the
northwestern US into early next, with continued prolonged low RH
from the Inland Northwest into the northern Rockies.

..Nauslar.. 08/21/2025

...Please see www.spc.noaa.gov/fire for graphic product...

$$