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U.S. Day 1 Fire Weather Outlook
ZCZC SPCFWDDY1 ALL
FNUS21 KWNS 301655
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1155 AM CDT Mon Jun 30 2025
Valid 301700Z - 011200Z
...Northern California and Southwestern Oregon...
An approaching mid-level trough, steep low-level lapse rates and
increasing mid-level moisture and instability will aid a mix of
wet/dry thunderstorm development across the higher terrain of
northern California, with showers and thunderstorms propagating into
southern Oregon along and east of the Cascades through this evening.
Isolated dry thunderstorm highlights persist where new ignitions are
possible atop dry fuels.
...Great Basin...
The mid-level trough entering California and associated stronger
southerly mid-level flow will overspread the Great Basin today. A
deep, well-mixed boundary layer will facilitate gusty surface winds
from the south of up to 25 mph across central Nevada, with sustained
winds of around 15 mph. The enhanced winds along with low relative
humidity will promote an elevated fire weather threat amid receptive
fuels.
..Williams.. 06/30/2025
.PREV DISCUSSION... /ISSUED 0215 AM CDT Mon Jun 30 2025/
...Synopsis...
Across the US, sub-tropical ridging will build over the Plains,
keeping stronger flow aloft displaced to the north while an upper
low will overspread portions of the West Coast. Ahead of the low,
breezy southerly winds will advect monsoon moisture northward into
parts of CA and OR. Dry thunderstorms and dry/breezy conditions
appear likely to support elevated fire-weather potential across the
Northwest and Great Basin today.
...Northwest...
Weak ascent from an approaching upper trough will allow for isolated
to widely scattered thunderstorms across northern CA and southern OR
through tonight. Strong heating and dry sub-cloud layers with steep
lapse rates below 500mb will support a mixed wet/dry thunderstorm
environment capable of occasional dry lightning strikes.
Additionally, erratic outflow winds are likely near storms. The
increased potential for dry lightning atop receptive fuels, warrants
continuation of IsodryT probabilities where fire starts are
possible.
...Great Basin...
Beneath the upper ridge, very hot surface temperatures are expected
over parts of NV and western UT. Southerly surface winds may gust to
15-20 mph through the afternoon, concurrent with widespread RH
values below 15%. The presence of breezy low-level winds and the
hot/dry conditions will overlap with a progressively drier and
receptive fuels across NV. This could support a few hours of
elevated fire-weather potential through this evening.
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U.S. Day 2 Fire Weather Outlook
ZCZC SPCFWDDY2 ALL
FNUS22 KWNS 301957
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0257 PM CDT Mon Jun 30 2025
Valid 011200Z - 021200Z
...Northern California into Oregon...
Upper-level low and favorable convective environment will support a
mix of dry/wet thunderstorms mainly across the higher terrain of
northern California into much of southern and central Oregon.
Isolated dry thunderstorm highlights were adjusted slightly
southward along the California Coastal Range and northern Sierra
Nevada.
...Great Basin...
The mid-level trough and associated elevated mid-level flow will
promote elevated to locally critical fire weather conditions across
much of central and eastern Nevada. South winds of 15-20 mph
combined with relative humidity at or below 15 percent will support
higher wildfire spread potential within dry fuels.
...Central Utah into Northwestern Arizona...
Isolated dry thunderstorm threat was expanded into northwestern
Arizona for Tuesday. Deeper monsoon moisture will remain south of
the Mogollon Rim Tuesday with a mix of wet and dry thunderstorms
expected in the afternoon. Fuels remain dry with potential dry
lightning ignitions away from heavier precipitation cores.
..Williams.. 06/30/2025
.PREV DISCUSSION... /ISSUED 0221 AM CDT Mon Jun 30 2025/
...Synopsis...
Mid-level flow across the CONUS should continue to amplify as the
sub-tropical ridge over the West gradually shifts eastward. The
upper low across the West Coast will intensify, spreading enhanced
flow aloft and monsoon moisture over much of the West. The increased
moisture will support dry thunderstorms over the Northwest and UT,
while warm and breezy conditions will favor elevated fire-weather
conditions over the Great Basin.
...Central Great Basin...
As the upper low over the West intensifies, enhanced mid-level flow
will overspread parts of the Great Basin and Southwest. On the
periphery of the building upper ridge, very warm and dry conditions
are likely. The stronger southerly mid-level flow over top the
dry/well-mixed boundary layer will support gusty southerly winds
across central/southern NV Tuesday. Widespread gusts of 15-25 mph
are expected, with RH values below 15%. As area fuels continuing to
dry, elevated to locally critical fire-weather conditions are
likely.
...Dry Thunderstorms...
A second day of thunderstorms is expected from northern CA into
southern OR and western ID Tuesday. Weak ascent from the upper low,
coupled with northward moving monsoon moisture will support
scattered storms through much of the day. Increased storm motions
and, steep low-level lapse rates will still favor relatively poor
precipitation efficiency. This suggests dry lighting is again
possible across the northern Coastal ranges of CA, east of the
Cascades to the OR/ID border.
Across parts of UT, the initial influx of deeper monsoon moisture
from the upper-level trough into the Intermountain West will support
isolated thunderstorms across the central mountains Tuesday. With
PWAT values of 0.7-0.8 inches and modest storm speeds, a mixed mode
of wet and dry storms is expected over the higher terrain. Very
receptive fuels (ERCs > 90th percentile), suggest dry lightning
ignitions are possible outside the heavier precip core.
U.S. Day 3-8 Fire Weather Outlook
ZCZC SPCFWDD38 ALL
FNUS28 KWNS 302153
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0453 PM CDT Mon Jun 30 2025
Valid 021200Z - 081200Z
...Day 3/Wednesday...
An incoming mid-level trough into the Pacific Northwest and
subsequent lee trough deepening across eastern Washington State will
promote stronger onshore flow into the region for Day 3/Wednesday.
Enhanced gap winds into the Columbia Basin and dry, downslope flow
east of the Cascades should support a fire weather threat where dry
fuels exist. A mix of wet/dry thunderstorms are expected across the
higher terrain of eastern Nevada, southwestern/central Utah and
southwestern Wyoming. This fire weather threat is primarily along
the western periphery of deeper monsoon moisture moving into the
greater Four Corners region.
...Days 4-5/Thursday-Friday...
Fire weather concerns will continue to be concentrated across the
portions of the Great Basin and Southwest for the latter part of the
week as another mid-level short wave trough moves into the region.
The thunderstorm threat is also present as the trough interacts with
residual monsoon moisture although considerable timing and amplitude
uncertainty precludes introduction of dry thunderstorm probabilities
for Day 4-5/Thursday-Friday.
...Days 6-8/Saturday-Monday...
An upper-level ridge shifts eastward into the eastern U.S. by the
weekend while a broad, dry southwest flow pattern infiltrates into
western U.S. Monsoon moisture, and general diurnal thunderstorm
development is expected to shift eastward along and east of the
Continental Divide, limiting the dry thunderstorm threat. Timing and
magnitude of mid-level short waves within the overall southwest flow
pattern precludes introduction of critical fire weather
probabilities at this time.
..Williams.. 06/30/2025
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