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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 292159
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0459 PM CDT Sun Jun 29 2025
Valid 011200Z - 071200Z
...Days 3-4/Tuesday-Wednesday...
An increasing fire weather threat is expected across portions of the
western U.S. as a mid-level low moves into California. Mid-level
moisture and instability north of the low will support isolated to
scattered showers and thunderstorms across the northern California
into southern Oregon, primarily along and east of the Cascades. A
mix of wet/dry thunderstorms will support new ignitions where over
available dry fuels. 40-50 knot southerly mid-level flow over a
dry/well-mixed boundary layer will support stronger south winds
across southern Nevada Day 3/Tuesday. An upper-level short wave and
increasing surface pressure gradients will bring enhanced west winds
into the Columbia Basin Day 4/Wednesday. The upper-level trough,
initial influx of deeper monsoon moisture into the Intermountain
West and daytime instability will support isolated dry thunderstorms
across the central Utah Mountains Day 3/Tuesday, with expanding
thunderstorm coverage heading into Day 4/Wednesday to include
western Wyoming/far southeastern Idaho as well as east-central
Nevada.
...Days 5-8/Thursday-Sunday...
Another mid-level short wave and associated stronger mid-level flow
entering the western U.S. late in the week will increase fire
weather concerns across the Great Basin on Day 6/Friday. Long term
ensemble guidance does indicate at least a weak upper-level
troughing pattern across the western U.S. but uncertainty remains in
specific fire weather impacts in the long term.
..Williams.. 06/29/2025
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