Wildfire in Washington, September 1 to 30, 2025

Area Forecast Discussion
National Weather Service Spokane WA
449 AM PDT Mon Sep 1 2025

.KEY MESSAGES...

- 15% chance showers and thunderstorms in Idaho Panhandle
  Monday.

- Hot temperatures next week, locally near 100, with Major to
  locally extreme HeatRisk. Record high temperatures for
  September possible for multiple locations.

&&

.SYNOPSIS...
Isolated thunderstorms are possible in Idaho today. Hot will
be in place through the week. High temperatures will climb back
into the upper 90s to near 100 degrees through much of the work
week.

&&

.DISCUSSION...

HOT WEATHER WITH WIDESPREAD MAJOR HEATRISK NEXT WEEK...

Monday: A deep area of low pressure will continue to spin over
Western WA today then begin its retreat offshore tonight. This
is 12 hours slower than modeled 24 hours ago. In the wake of
this morning's convection, drier midlevel air will work
northward into the region. This will lower the threat for
showers and thunderstorms though it is tough go completely dry
given the hot and unstable air mass in place and continued
difluence aloft. A few of the cam models hint at isolated
showers and thunderstorms redeveloping in the afternoon and
evening over areas of the North Idaho. Models did not handle a
handful of storms that formed over NE WA on Sunday so would not
completely rule out a few late day cells again Monday but
probabilities are very low and mainly focused along the ID/MT
border. A lot will ride on the presence of a weak warm layer
around 8000-9000 ft AGL and whether this holds convection at bay
or is weaker than expected and parcels are able to reach LCL
temps.

The low wobbles back into the Eastern Pacific Tuesday and high
pressure will strengthen and remain in control through much of
the week. This will deliver an early September heat wave with
temperatures nearly 20 degrees above 30-year averages topping
out in the 90s to 100s. It has been hot and muggy the last few
days and the mercury will continue to rise. Folks should plan
for moderate to major heat risk and take precautions like proper
hydration and breaks from the heat to avoid heat related
illnesses.

There are many active wildfires now burning around the region and
it is likely that haze and smoke will become an impact to some
communities in regards to health and keeping temperatures from
reaching potential highs. Once the low departs and winds become
more terrain driven, there will be less ventilation and we will
have a better idea on which communities that will be.

There remains considerable uncertainty with the evolution/breakdown
of the ridge Friday into the weekend as several low pressure
systems undergo phasing over the Pacific and into the Gulf of
AK. There is moderate confidence that the ridge axis will shift
eastward but low confidence, how far. I am seeing more ensembles
clustered together for a trough to move into the region by the
end of the weekend compared to runs 24 hours ago so this leads
to increased confidence for some degree of cooling and
precipitation chances for some. I am anticipating some degree of
increasing winds, especially in the lee of the Cascades as the
cross Cascade gradient restrengthens but little confidence in a
significant region-wide wind event at this time. /sb

&&

.AVIATION...
12Z TAFS: VFR conditions will prevail through the period for
TAF sites. Isolated thunderstorms are currently impacting the
region and expected to last through 16Z Monday. The storms are
not expected to impact TAF sites. Outflows from thunderstorms
could bring quick wind shifts.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
High confidence in VFR conditions at the TAF sites. Low
confidence on thunderstorms impacting TAF sites and low
confidence on timing and speeds of outflow wind shifts.

-----------------------

Confidence descriptors:
Low - Less than a 30 percent chance
Moderate - 30 to 70 percent chance
High - Greater than a 70 percent chance

For additional probabilistic information for NWS Spokane
airports, please refer to the Aviation Dashboard on our webpage:
https:/weather.gov/otx/avndashboard

&&

.Preliminary Point Temps/PoPs...
Spokane        97  64  99  64  99  63 /   0   0   0   0   0   0
Coeur d'Alene  97  65  99  64  99  63 /   0   0   0   0   0   0
Pullman        95  60  97  60  97  60 /   0   0   0   0   0   0
Lewiston      100  69 102  69 102  69 /   0   0   0   0   0   0
Colville       97  54 100  54  99  54 /   0   0   0   0   0   0
Sandpoint      93  60  97  57  95  57 /   0   0   0   0   0   0
Kellogg        97  68  98  67  96  67 /   0   0   0   0   0   0
Moses Lake     93  61  98  62 100  64 /   0   0   0   0   0   0
Wenatchee      93  70  99  72 101  73 /  10   0   0   0   0   0
Omak           97  66 101  67 102  68 /  10   0   0   0   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
WA...Heat Advisory until 8 PM PDT Thursday for Lower Garfield and
     Asotin Counties-Okanogan Valley-Spokane Area-Upper
     Columbia Basin-Waterville Plateau-Wenatchee Area.
     Heat Advisory from 11 AM Tuesday to 8 PM PDT Thursday for
     Central Chelan County-Moses Lake Area-Okanogan Highlands-
     Washington Palouse-Western Okanogan County.
     Red Flag Warning until 11 AM PDT this morning for Colville
     Reservation (Zone 702)-East Portion of North Cascades
     National Park/Lake Chelan National Recreation Area (Zone
     697)-East Washington Central Cascades (Zone 696)-East
     Washington North Cascades (Zone 698)-Foothills of Central
     Washington Cascades (Zone 705)-Methow Valley (Zone 704)-
     Okanogan Highlands and Kettle Mountains (Zone 699)-
     Okanogan Valley (Zone 703)-Waterville Plateau (Zone 706).
ID...Heat Advisory until 8 PM PDT Thursday for Coeur d'Alene Area-
     Lewiston Area.
     Heat Advisory from 11 AM Tuesday to 8 PM PDT Thursday for
     Idaho Palouse-Lewis and Southern Nez Perce Counties.
     Air Quality Alert until 10 AM PDT Tuesday for Lewis and
     Southern Nez Perce Counties-Lewiston Area.

&&