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U.S. Day 1 Fire Weather Outlook
ZCZC SPCFWDDY1 ALL
FNUS21 KWNS 021653
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1153 AM CDT Wed Jul 02 2025
Valid 021700Z - 031200Z
...Nevada...
Anomalously high precipitable water values, including observed an
observed value of nearly 1 inch from the 1200Z Las Vegas sounding,
suggests higher precipitation efficiency from expected showers and
thunderstorms moving into southern Nevada today. This will limit dry
lightning ignition efficiency across southern Nevada. A relatively
dry sub-cloud layer remains in place across central and northern
Nevada, where initially high-based shower and thunderstorm
development is expected through the day, increasing potential for
ignition over dry fuels denoted by a general northward shift in
Isolated Dry Thunderstorm highlights.
...Far Northeastern California into southeastern Oregon...
Stronger mid-level winds and accelerated northeast thunderstorm
motions owing to an encroaching mid-level trough into the Pacific
Northwest will limit precipitation and increase ignition likelihood
amid drier fuels across northeastern California into southeastern
Oregon this afternoon. Isolated Dry Thunderstorm highlights were
added to reflect this threat for today.
..Williams.. 07/02/2025
.PREV DISCUSSION... /ISSUED 0225 AM CDT Wed Jul 02 2025/
...Synopsis...
Mid-level troughing is forecast to slowly progress across central CA
today, while another trough moves onshore across WA. Decreasing
heights over the Northwest will continue to provide southerly
transport of monsoon moisture into portions of the Great Basin and
Intermountain West, where numerous thunderstorms are likely. Dry and
breezy conditions will also be likely over the Cascades and western
Columbia Basin.
...Lee of the Cascades...
Increasing flow aloft ahead of the Pacific trough will favor dry
downslope winds across the Cascades and western Columbia Basin. With
daytime temperatures well into the 90s F, deep mixing will promote
low boundary layer RH of 15-20%. With downslope winds of 15-25 mph,
widespread elevated fire-weather conditions are likely on the lee
slopes and through the gaps of the higher terrain. Some localized
critical conditions are also possible where the terrain-enhanced
winds and locally drier conditions may develop for a few hours this
afternoon.
...Great Basin and northern Rockies Dry Thunder...
East of the upper low, widespread thunderstorm activity is expected
across the Great Basin and western slopes of the Rockies. A monsoon
surge of 0.8 to 1.0 inch PWATs will lift northward across
central/eastern NV into UT and western CO/WY. Weak ascent from the
trough, along with diurnal heating of the terrain will result in
scattered to numerous high-based showers and thunderstorms by early
afternoon. Additional storms are likely along a cold front across ID
and western MT. Given the increasing moisture content and continued
southerly flow, some wetting rainfall is expected from training
rounds of thunderstorms. A mix of wet and dry thunderstorms will
support potential lightning ignitions, particularly with fast moving
cells and on the edges of the most intense downdraft cores. This
appears most likely across parts of eastern UT and western CO where
less wetting rainfall is expected. Though isolated dry strikes are
possible over the entire IsoDryT area.
...Northern OR/Southern CA...
Scattered thunderstorms are again expected ahead of the upper low. A
few of these storms may be drier with 30+ kt of southerly flow and
relatively deeply mixed boundary layers. While a few dry strikes are
possible outside of the heavier cores, recent QPE estimates of 0.5
to 1 inches indicate area fuels have likely been tempered to some
degree. This suggests the threat for dry lightning is below IsoDryT
thresholds.
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U.S. Day 2 Fire Weather Outlook
ZCZC SPCFWDDY2 ALL
FNUS22 KWNS 021958
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0258 PM CDT Wed Jul 02 2025
Valid 031200Z - 041200Z
...Northern Great Basin and Western Nevada...
An approaching short wave trough and stronger mid-level flow will
support shower and thunderstorm development across northeastern CA
into southeastern OR Thursday. Faster northeast thunderstorm
trajectories will limit precipitation amounts supporting an isolated
dry thunderstorm threat. A corridor of daytime instability and
precipitable water values of 0.5 to 0.7 inches will bring an
isolated dry thunderstorm threat to the higher terrain of far
northern NV, northern UT as well as far southeastern ID. The
incoming trough will also promote stronger downslope flow east of
the Sierra Crest across northwestern NV. Enhanced downslope winds
from the west of 15-20 mph and relative humidity of around 15%
supports continuation elevated fire weather highlights.
...Western Slope and Eastern Utah...
A broad plume of monsoon moisture over the region along with daytime
heating will promote a mix of wet and dry thunderstorms over higher
terrain of the Western Slope as well as eastern UT. Some lightning
ignitions are possible within remaining pockets of receptive fuels.
..Williams.. 07/02/2025
.PREV DISCUSSION... /ISSUED 0227 AM CDT Wed Jul 02 2025/
...Synopsis...
Broad troughing over the western US will continue as a compact
shortwave trough moves across northern CA Thursday. 40-50 kt
westerly flow will overspread the northern Great Basin. This will
encourage dry downslope flow across parts of western NV. At the same
time, continued monsoon moisture will allow widespread showers and
thunderstorms over the Intermountain West.
...Northwest Great Basin...
Continued westerly flow aloft will overspread the northern Great
Basin Thursday afternoon. Dry downslope winds of 15-25 mph are
expected, aided by the increasing winds aloft. Very warm
temperatures, and the dry downslope trajectories, will support
widespread RH values below 15%. The increase in surface winds amid a
warm and dry boundary layer and dry fuels will support elevated
wildfire spread potential Thursday.
...Western Slope...
Another day of widespread showers and thunderstorms is expected
across the eastern Great Basin and western Rockies Thursday. A
continued surge of robust monsoon moisture (PWATS above 0.8 inches)
will support a mixed mode of wet and occasionally dry storms.
Widespread QPF of 0.1-0.25 inches in the preceding days suggest area
fuels are likely to become less receptive to lightning ignitions
with time. However, the coverage of storms does support at least
isolated potential for dry strikes in receptive fuels across western
CO/WY into eastern UT.
U.S. Day 3-8 Fire Weather Outlook
ZCZC SPCFWDD38 ALL
FNUS28 KWNS 022153
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0453 PM CDT Wed Jul 02 2025
Valid 041200Z - 101200Z
...Day 3/Friday...
A negatively tilted short-wave trough and attendant mid-level wind
maxima entering into the western U.S. on Day 3/Friday will increase
fire weather concerns across much of the Great Basin. The stronger
dry, southwest flow will scour out remaining monsoon moisture across
the much of NV and southwest UT resulting in a deep, well mixed
boundary layer and low surface relative humidity. In addition,
widespread showers and thunderstorms ahead of the trough will affect
portions of eastern Oregon and Northern Rockies region.
...Day 4-8/Saturday-Wednesday...
A mid-level trough will lift into the Northern High Plains on Day
4/Saturday with a broad but reduced southwest flow pattern
continuing to push remaining monsoon moisture and associated high
terrain convection along and east of the Continental Divide by Day
5/Sunday, mitigating the threat of new lightning ignitions for much
of the Intermountain West. A building mid-level ridge over the
Desert Southwest will support climbing temperatures to above
seasonal averages across much of the West starting early next week.
This pattern could also usher in another round of monsoon moisture
into the Lower Colorado River Basin and southern California as early
as Day 5/Sunday, although enough forecast uncertainty exists to
preclude critical probabilities of dry thunderstorms at this time.
..Williams.. 07/02/2025
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