150
FXUS66 KOTX 312302
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
402 PM PDT Sun Aug 31 2025

.KEY MESSAGES...

- 10-15% chance for sprinkles today. 15-30% chance for showers
  and dry thunderstorms Sunday night in Central Washington.

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

&&

.SYNOPSIS...
Today will feature scattered clouds and sprinkles. There is a
risk for showers and dry thunderstorms tonight in Central WA. A
strong ridge of high pressure will begin to build in this
weekend. Hot temperatures return with the ridge that will extend
through next week. High temperatures will climb back into the
upper 90s to near 100 degrees.

&&

.DISCUSSION...

...HOT WEATHER WITH WIDESPREAD MAJOR HEATRISK NEXT WEEK...

Labor Day Weekend: Temperatures today have risen a few degrees from
yesterday as a trough strengthens further over the Western US.
Today, highs will be in the low to mid 90s, which is over ten
degrees hotter than normal for this time of year. As the ridge
strengthens, temperatures will warm further. As it stands, much of
the area is already seeing Moderate Heat Risk chances with some
isolated Major Heat Risk. As things warm further, Major Heat Risk
will extend into more area, with even some Extreme Heat Risk values
near Wenatchee. Because of the extended duration of this late summer
heat wave and the fact that the holiday weekend has begun and people
will be taking to outdoor activities, a Heat Advisory has been
issued for the areas of: Okanogan Valley, Wenatchee, Waterville
Plateau, upper Columbia Basin, Spokane/Coeur d`Alene, and lower
Garfield and Asotin county. The low pressure system spinning off the
Pacific Northwest will begin weakening and retrograding east, giving
the ridge the chance to build further and result in continued
increased temperatures in the coming days. However, the low pressure
system will provide enough lift to the area to bring a 15-25 percent
chance of thunderstorms this evening and overnight to the Cascades,
with these chances stretching as far east as Republic down to Moses
Lake. With the drier environment, rain amounts will be very light.
With how dry the fuels are, combined with the heat and low relative
humidity, the biggest risk will be lightning ignited fire starts and
gusty outflow winds, which could lead to increased fire activity. As
a result, a Red Flag Warning has been issued for the Cascades, the
foothills of the Central Washington Cascades, Okanogan Valley, and
Waterville Plateau from 9pm PDT this evening through 11am PDT
tomorrow morning. If that wasn`t enough, smoke from fires down south
will spread northward into the general area, bringing haze to the
skies through at least Monday, which could result in some degraded
air quality.

Tuesday through Thursday: As the aforementioned ridge strengthening
continues, temperatures will rise further. When these ridge heights
peak on Wednesday, they will be anomalously high for this time of
year. With the subsequent increase in 850mb temperatures, widespread
Major to locally Extreme Heat Risk will be seen throughout much of
the area. Temperatures are projected to get into the high 90s and
even some triple digits, with some lower valley areas getting into
the triple digits by Tuesday and continuing through Thursday.
Tuesday and Wednesday look to be the hottest days of this warmup.
NBM probabilities for temperatures reaching 100 degrees currently
sit at over 50 percent for a large part of the area Tuesday and
Wednesday. For the Spokane/Coeur d`Alene area, probabilities of
hitting triple digits sit at 70 percent and above. For Wednesday,
these chances decrease to 45 percent and above, but are still quite
high for this time of year. As these forecasted highs stand, some
places could see monthly records broken for September. Smoke models
still show a chance of haze through the week, which could lead to
some declining air quality. Several areas have been added to the
Heat Advisory, and they include Western Okanogan County, Central
Chelan County, Moses Lake Area, WA/ID Palouse, Lewis and Southern
Nez Perce Counties, and the Okanogan Highlands. The Heat Advisory
for this starts Tuesday at 11am and goes through 8pm Thursday night.
With Major Heat Risk, and temperatures being this high for an
extended amount of time, almost everyone without access to adequate
hydration and cooling will be at risk of heat-related illnesses.

As temperatures warm, relative humidity will drop. By Tuesday,
values will drop into the low teens. With high lapse rates at 8
degC/km and some local 9 degC/km, all signs are pointing to a hot,
dry and unstable atmosphere for fire weather, which could lead to
increased fire activity. We will keep a close eye on this as things
progress to see if a need arises for any other fire products later
in the week.

Friday through Sunday: Unfortunately, many long range models are
still showing temperatures in the high 80s and low 90s Friday
through next weekend. Cluster analysis is very agreeable on
anomalously high heights staying over the area Friday and Saturday.
Heat Risk values on Friday still indicate widespread Moderate to
locally Major Heat Risk, which could lead to an extension in any
heat products should temperatures warm further or Heat Risk rises to
Moderate for more areas. On Sunday, agreement splits, with half of
the clusters favoring continued warm conditions and half the
clusters favoring a cooldown with the possibility of some rain.
/AS

&&

.AVIATION...
00Z TAFS: VFR conditions will prevail through the period for
TAF sites. Possibility for haze at times but not confident it
will drop visibilities to 6SM or less, so did not include them
in the TAFs. COE will get a bit breezy near the end of the
forecast period. There is a 15-25 percent chance of
thunderstorms near EAT/MWH starting around 01Z and continuing
through 10Z. After around 15-16Z, most mid level clouds will be
gone and high level clouds or clear skies will prevail.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
High confidence in VFR conditions at the TAF sites. High
confidence in smoke resulting in haze for
GEG/SFF/COE/MWH/LWS/PUW beginning at varying times but low
confidence it will be thick enough to drop visibilities to 6SM.
Moderate confidence in thunderstorms from 01-10Z for EAT/MWH.

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

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        64  96  63  98  64  98 /  10   0   0   0   0   0
Coeur d`Alene  65  96  64  98  64  98 /  10   0   0   0   0   0
Pullman        60  95  59  97  60  96 /   0   0   0   0   0   0
Lewiston       68 100  69 101  68 101 /  10   0   0   0   0   0
Colville       54  96  54  99  55 100 /  10  10   0   0   0   0
Sandpoint      60  93  59  96  58  96 /  10  10   0   0   0   0
Kellogg        67  95  67  97  67  96 /  10   0   0   0   0   0
Moses Lake     63  93  61  98  63 101 /  20  20   0   0   0   0
Wenatchee      68  93  69  99  72 102 /  30  20   0   0   0   0
Omak           68  98  66 101  68 102 /  30  20   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 from 9 PM this evening to 11 AM PDT Monday
     for 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
     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.

&&

$$