919
FNUS21 KWNS 021653
FWDDY1

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.

...Please see www.spc.noaa.gov/fire for graphic product...

$$