Fire Weather Outlook Discussion
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095
FNUS28 KWNS 312121
FWDD38

Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0419 PM CDT Sun Aug 31 2025

Valid 021200Z - 081200Z

A mid/upper-level ridge is forecast to build north/northwestward
across much of the western U.S. and extend into portions of British
Columbia Day 3/Tuesday into Day 4/Wednesday. Meanwhile, a compact
mid/upper-low is forecast to meander north/northeastward along the
western periphery of the ridge, coming onshore over portions of
central/northern California Day 3/Tuesday. Thereafter, the evolution
of the low remains somewhat uncertain due to poor inter/intra-model
variability regarding timing. Nevertheless, the low should generally
drift slowly into portions of Oregon by Day 4/Wednesday or Day
5/Thursday.

...Day 3/Tuesday - Day 5/Thursday: California and the Northwest...
Hot, dry, and unstable conditions are forecast to develop Day
4/Tuesday across much of California and the Northwest and persist
through at least the middle of the week as the aforementioned
upper-level ridge builds into the area. This may promote increasing
fire activity from recent holdovers, longer burn periods on any
ongoing large fires, and an increasing risk for large
plume-dominated fires.

Lightning potential is also forecast to increase across portions of
northern California into Oregon Day 3/Tuesday through Day
4/Wednesday, as the aforementioned upper-low drifts northward and
increasing moisture and ascent interact with a hot and unstable
atmosphere. Primary forecast challenge remains the evolution of the
low, with key differences still present in ensemble guidance
regarding how quickly the low moves northward - especially late Day
4/Wednesday through Day 5/Thursday. Nevertheless, dry thunderstorm
probabilities (10-39%) were introduced for Day 3/Tuesday and Day
4/Wednesday for where the most favorable overlap of thunder
potential atop receptive fuels is currently expected. These areas
may need to be refined and an additional area may need to be added
for Day 5/Thursday as guidance comes into better agreement.

..Elliott.. 08/31/2025

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

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