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U.S. Day 1 Fire Weather Outlook
ZCZC SPCFWDDY1 ALL
FNUS21 KWNS 181610
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1110 AM CDT Fri Jul 18 2025
Valid 181700Z - 191200Z
Scattered thunderstorms with a combination of wet/dry modes are
expected across portions of the Northern Great Basin today as
relatively deeper moisture from an upper-low over southern
California impinges on the area. At 12 UTC, the precipitable water
value at Elko, NV was 0.71 inches (near the 90th percentile) and at
Salt Lake City, UT 0.87 inches (near the 80th percentile), with
ensemble guidance suggesting further increases today. Despite the
scattered thunderstorm coverage, new ignitions may be somewhat
limited by the trend toward wetter storm modes. Nevertheless, at
least isolated dry thunderstorms will be possible on the fringe of
the deeper moisture and along the periphery of any stronger storm
cores. Additionally, gusty and erratic outflow winds in excess of 50
mph are possible from nearby thunderstorms - especially across
portions of northeast Nevada, northwest Utah, southeast Idaho,
western Wyoming, and southwest Montana. Please see the latest SPC
Day 1 Convective Outlook for more information on the severe weather
potential in this area.
Elevated to locally critical fire weather conditions remain possible
this afternoon from the Cascade gaps into the Columbia Basin and
central Oregon. The forecast remains mostly on-track across this
area with only minor adjustments needed based on the latest ensemble
forecast guidance.
Please see the previous discussion below for more information on
today's fire weather forecast.
..Elliott.. 07/18/2025
.PREV DISCUSSION... /ISSUED 1216 AM CDT Fri Jul 18 2025/
...Synopsis...
Ridging aloft will be present across the southern half of the CONUS
with a belt of stronger mid-level winds within the northern tier
states. A weak upper-level low will remain nearly stationary in
southern California/northern Baja.
...Northwest...
Dry and windy conditions are most likely to occur within the Cascade
gaps eastward into Columbia Basin and central Oregon. Here, surface
winds of 15-20 mph will overlap afternoon RH of 15-20%. Some locally
critical fire weather is possible in the Cascade gaps where winds
will be stronger. However, RH may only briefly fall to critical
levels.
...Northern Great Basin...
Modest mid-level moisture return will be aided by the weak upper low
in southern California. A few dry thunderstorms are possible on the
northern/northwest fringe of the mid-level moisture. Storms may be a
combination of both wet/dry modes due to relatively weak
mid/upper-level flow.
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U.S. Day 2 Fire Weather Outlook
ZCZC SPCFWDDY2 ALL
FNUS22 KWNS 180518
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1218 AM CDT Fri Jul 18 2025
Valid 191200Z - 201200Z
...Synopsis...
A low-amplitude upper level trough will pivot through the Northwest
on Saturday. In the lee of the northern Rockies, a surface low will
deepen in central Montana. Mid-level moisture will be pushed
slightly southward and eastward by the sagging upper trough in the
Northwest. Additional thunderstorms are possible in the parts of the
central/eastern Great Basin. However, PWAT values and slower storm
motions do not suggest a significant threat for new ignitions.
...Columbia Basin and northern Nevada/southern Idaho...
Elevated fire weather conditions are again expected in the Columbia
Basin. With the core of the mid-level jet primarily being east of
the region by the afternoon, the overall setup should favor slightly
less strong wind coverage. Winds of 15-20 mph are still possible. RH
may be a touch higher than on Friday with around 20% being probable
during the afternoon.
With the trough sagging southward and the surface low deepening, a
zone of 15-20 mph (locally higher) winds is possible in parts of the
northern Great Basin. RH could fall as low as 10-15% by the
afternoon.
..Wendt.. 07/18/2025
U.S. Day 3-8 Fire Weather Outlook
ZCZC SPCFWDD38 ALL
FNUS28 KWNS 172155
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0455 PM CDT Thu Jul 17 2025
Valid 191200Z - 251200Z
...Days 3-5/Saturday-Monday...
A mid-level trough and attendant dry cold front will move through
the Pacific Northwest on Day 3/Saturday. Robust onshore flow will
persist across the Cascades, bringing breezy conditions to the
Columbia Basin. Despite cooler post-frontal temperatures, sustained
west winds of around 15 mph (20 mph in favored Cascade gaps) and
relative humidity as low as 15 percent will support a fire weather
threat amid dry fuels across the Columbia Basin. Enhanced mid-level
flow at the base of the trough overrunning a dry boundary layer in
place across southern Idaho will bring stronger winds to the Snake
River Plain Day 3/Saturday, raising wildfire spread potential within
critically dry fuels. A deepening, positively-tilted trough across
the Pacific Northwest and increase in mid-level winds will support a
broader area of dry southwesterly flow across the Great Basin, NV
and southern ID by Day 4/Sunday, with the fire weather threat
shifting southeastward to include northwestern UT by Day 5/Monday.
The trough will also aid in pushing residual monsoon moisture and
thunderstorm development currently across portions of the
Intermountain West along and east of the Continental Divide by early
next week, while also mitigating fire weather concerns for the
Pacific Northwest as cooler temperatures, cloud cover and higher
relative humidity move into the region.
...Days 6-8/Tuesday-Thursday...
Long term ensemble guidance indicates some form of mid-level
troughing persisting across the Pacific Northwest through the middle
of next week, maintaining a dry southwesterly flow over much of the
interior of the West. However, relaxing mid-level flow and reduced
surface pressure gradients as a subtropical high propagates westward
across the southern U.S. should promote lighter winds across the
Southwestern U.S., particularly for Days 7-8/Wednesday-Thursday.
..Williams.. 07/17/2025
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