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Day 3-8 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
0353 PM CDT Sun Jul 21 2024

Valid 231200Z - 291200Z

Fire weather concerns during the extended period will focus on parts
of the Northwest, northern Great Basin, and northern Rockies. Dry
and windy conditions, as well as dry thunderstorms, are possible
ahead of an upper-level trough that will promote some upper-level
ridge breakdown in the West.

...Wind/RH Concerns...
Winds will begin to increase in the northwest into northern
California as the trough approaches on Wednesday. At this time, the
strongest winds appear they may remain closer to the terrain/Cascade
Gaps. Winds will likely peak on Thursday across the Northwest into
northern California/northwest Nevada. Critical fire weather is
perhaps most likely Thursday, but there will also be some increase
in RH as well. Confidence is not high enough for greater critical
fire weather probabilities at this time.

By Friday, strong mid-level flow will remain over parts of the
northern Rockies. Additionally, a weak tropical low will rejoin the
mean westerlies aloft and move into central California and the
western Great Basin into the weekend. Strong winds and low RH are
possible from the western Great Basin into western/central Montana
on Friday and Saturday. However, there are differences between the
ECMWF/GFS on the timing and intensity of some key features. When
co*paring the deterministic models to their counterpart ensembles,
it suggests that there is large spread in potential outco*es. This
uncertainty precludes introducing highlights.

...Dry Lightning...
Mid-level moisture will remain across the northern Great Basin into
the adjacent Northwest on Tuesday. Large-scale ascent will be weaker
than on previous days and coverage is still somewhat uncertain.
Available CAM and global guidance shows some potential for
thunderstorms from far northern Nevada into central Idaho. Some of
these storms may produce little rainfall.

Thunderstorm potential for the northern Great Basin into parts of
eastern Oregon, northeast California, and southwest Montana will
increase on Wednesday. At least subtle forcing from an approaching
trough should support some increase in storm coverage. Slightly
faster storm motions should also increase the probability of a few
drier storms.

Mid-level moisture will shift eastward as the trough progresses.
There is a consistent signal in models for thunderstorms from
central Idaho into southwest and parts of central Montana. Forcing
for ascent will be moderately strong as the trough moves into the
region by late afternoon. Between dry sub-cloud layers and fast
storm motions, confidence in dry thunderstorms is moderate to high.

..Wendt.. 07/21/2024

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