491
FNUS21 KWNS 091658
FWDDY1

Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1157 AM CDT Wed Jul 09 2025

Valid 091700Z - 101200Z

...CRITICAL FIRE WEATHER AREA FOR EASTERN NEVADA AND FAR WESTERN
UTAH...

...Montana...
A mid-level trough translating east across the Canada/U.S. border
and subsequent breakdown of upper-level ridge over the Northern
Rockies along with sufficient mid-level moisture/instability will
aid in high-based thunderstorm development across the higher terrain
of western MT, moving into eastern MT by evening. Fast
east-northeastward thunderstorm trajectories on the order of 25-30
knots will limit rainfall (in addition to gusty/erratic outflow
winds) over dry fuels, supporting an increased wildfire spread
potential for portions of central and eastern MT where isolated dry
thunderstorm highlights were added.

Otherwise, previous forecast (see below) for additional fire weather
threats across the Western U.S. remains on track with minimal
changes.

..Williams.. 07/09/2025

.PREV DISCUSSION... /ISSUED 0156 AM CDT Wed Jul 09 2025/

...Synopsis...
A compact midlevel trough will advance eastward across the northern
Great Basin during the day. At the same time, a separate large-scale
trough will move eastward across western Canada.

...Great Basin...
Preceding the compact midlevel trough, moderate deep-layer
southwesterly flow will overspread the Great Basin during peak
heating. Deep boundary-layer mixing into this strengthening flow
aloft will result in an expansive area of lower-teens RH and 20-25
mph sustained west-southwesterly surface winds. Given increasingly
dry fuels across the region, critical fire-weather conditions are
expected from central NV into western UT (with elevated conditions
surrounding this area across the Great Basin).

...Northwest...
Large-scale ascent accompanying the compact midlevel trough will aid
in isolated to widely scattered thunderstorm development over
southeastern OR, southwestern ID, and far northeastern CA during the
afternoon/evening hours. Deep inverted-V soundings and 0.5-0.7 inch
PW will favor dry thunderstorms -- with a risk of lightning-induced
ignitions and strong/erratic outflow winds.

Additionally, strong westerly flow in the base of the large-scale
trough moving across western Canada will persist across the
Cascades. Despite slightly higher RH than previous days, strong
downslope/westerly surface winds will favor elevated to locally
critical fire-weather conditions in the Columbia Basin.

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

$$