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U.S. Day 1 Fire Weather Outlook
ZCZC SPCFWDDY1 ALL
FNUS21 KWNS 031700
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1200 PM CDT Thu Jul 03 2025
Valid 031700Z - 041200Z
...Central California...
An approaching mid-level short wave trough will promote enhanced dry
downslope winds along and leeward of the Diablo Range into the San
Joaquin Valley this afternoon. West-northwest winds of 10-15 mph
with locally sustained 20 mph combined with relative humidity as low
as 10% will support a few hours of elevated fire weather conditions
amid dry fuels.
...Northern Great Basin and Upper-Colorado River Basin...
Isolated dry thunderstorm threat was expanded into south-central OR
and north-central NV with latest model guidance and observed
soundings indicating precipitable water values holding in the
0.50-0.80 inch range for this afternoon. The advancing short-wave
trough will support faster storm motions particularly across
southeastern OR. In addition, falling 500 DM heights and mid-level
jet support will keep a nocturnal thunderstorm threat for
southeastern OR and southern Idaho through 12Z Friday. Otherwise, a
mix of wet/dry thunderstorms across the Upper CO River Basin and
central Mountains of UT could support new ignitions in pockets of
existing dry fuels.
..Williams.. 07/03/2025
.PREV DISCUSSION... /ISSUED 0211 AM CDT Thu Jul 03 2025/
...Synopsis...
A compact shortwave trough moving across northern CA will accompany
40-50 kt westerly flow across the northern Great Basin. This will
encourage dry downslope flow across parts of western NV and the
northern Great Basin. At the same time, continued monsoon moisture
will allow scattered showers and thunderstorms over the
Intermountain West with isolated lightning.
...Northern Great Basin...
Dry and breezy conditions are expected today and tonight in the lee
of the Sierra and northern Great Basin ahead of the shortwave
trough. Sustained 15-20 mph surface winds are expected from the
west/southwest through the day. A dry and deep boundary layer will
also support RH below 15-20%. Despite some recent rainfall, area
fuels remain receptive across much of NV and the northern Great
Basin. Widespread elevated and locally critical fire-weather
conditions are likely.
...Dry Thunder...
As the upper trough moves into the West, monsoon moisture will be
shunted eastward compared to the last several days. Still, PWATS
around 0.6-0.8 inches across western CO and into the northern
Rockies will be sufficient to support scattered showers and
thunderstorms this afternoon and evening. Fuel receptiveness has
decreased with multiple rounds of showers and storms this week.
Still, drier pockets remain and lightning outside of the heavier
precipitation cores will be capable of ignitions. This appears most
likely over parts of northern CO to eastern ID, where less rainfall
has been observed. Will maintain IsoDryT highlights for occasional
lighting strikes within receptive fuels.
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U.S. Day 2 Fire Weather Outlook
ZCZC SPCFWDDY2 ALL
FNUS22 KWNS 031952
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0252 PM CDT Thu Jul 03 2025
Valid 041200Z - 051200Z
...CRITICAL FIRE WEATHER AREA FOR SOUTHEASTERN NEVADA AND SOUTHWEST
UTAH...
...Great Basin...
A mid-level trough moving into the Northwestern U.S. will introduce
stronger mid-level winds as well as introducing an increasingly dry
air mass into the region Friday. Development a dry and well-mixed
boundary layer across much of Nevada along with sustained southwest
surface winds of 15-25 mph and relative humidity falling to around
15% will support a critical fire weather threat across southeastern
NV and southwestern UT Friday afternoon. Recent observed rainfall
across this area has been minimal, allowing fuels to largely remain
receptive to wildfire spread. An elevated fire weather threat
remains over much of western and northern Nevada.
...Southeast Oregon...
The aforementioned mid-level trough will also promote isolated to
scattered thunderstorms across southeastern OR and far northeastern
CA/far northwestern NV. Nocturnal thunderstorms will likely be
ongoing across southeastern Oregon early Friday owing to a more
supportive convective environment from the mid-level trough and
associated jet. Additional shower and thunderstorm development is
likely Friday afternoon amid an increase in daytime destabilization.
Recent rainfall across southeast Oregon has been limited allowing at
least some fuels to remain receptive to potential lightning
ignitions.
..Williams.. 07/03/2025
.PREV DISCUSSION... /ISSUED 0211 AM CDT Thu Jul 03 2025/
...Synopsis...
Western US troughing will intensify and shift eastward Friday as
westerly flow aloft overspreads the Great Basin. Dry downslope winds
are expected over much of the West. Elevated to critical
fire-weather conditions are possible, along with a few thunderstorms
Friday.
...Great Basin and Northern Rockies...
Westerly flow aloft is forecast to increase as the shortwave trough
over the West moves eastward. Dry downslope flow and warm
temperatures are expected across much of NV into western UT Friday.
Widespread westerly winds of 15-20 mph are expected. The stronger
dry, southwest flow will advected drier air across the much of NV
and southwest UT, resulting in a deep, well mixed boundary layer and
low surface relative humidity. Dry and deep boundary layer will also
support RH below 15%. Widespread elevated and locally critical
conditions are likely. Especially across southern NV into southwest
UT, where winds may approach 25 mph sustained with RH below 15%.
Along the eastern periphery of the drier air, isolated showers and
thunderstorms are possible again. Recent rainfall has reduced fuel
receptiveness across much of the Western Slope and eastern Great
Basin. Some lightning may occur with a mix of wet and dry storms
from ID, into southern MT, WY, and northern CO. However, the mixed
fuels, and another potential round of wetting rainfall suggests the
threat for dry strikes over receptive fuels is low.
U.S. Day 3-8 Fire Weather Outlook
ZCZC SPCFWDD38 ALL
FNUS28 KWNS 032155
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0455 PM CDT Thu Jul 03 2025
Valid 051200Z - 111200Z
...Day 3/Saturday...
A mid-level short wave trough will lift into the Montana and
northern High Plains through Day 3/Saturday. Widespread wetting
rains are expected across much of the Northern Rockies while
lingering southwest flow will present a fire weather threat to
portions of southeastern NV/southwestern UT. Elevated mid-level
winds along with a well-mixed boundary layer will support breezy and
dry conditions for the southern Great Basin on Day 3/Saturday, where
40 percent critical probabilities have been added.
...Days 4-8/Sunday-Thursday...
A building Four Corners high along with a quasi-stationary mid-level
low offshore of northern CA will support a persistent dry, southwest
flow pattern over the Southwestern U.S. and Great Basin Region from
Day 4-7/Sunday-Wednesday. A primary impact of the building mid-level
ridge will be increasing heat across the Western U.S., promoting
drying of fuels across the region while southwest aloft keeps
monsoon moisture and associated showers and thunderstorms confined
to the Continental Divide and southern Arizona. Ensemble guidance
suggests a slight shift westward of the Four Corners high towards
the lower Colorado River basin midweek, potentially inviting a push
of monsoon moisture into Southern California and Great Basin Days
7-8/Wednesday-Thursday. However, uncertainty remains high enough to
preclude critical probabilities for dry thunderstorms at this time.
..Williams.. 07/03/2025
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