059
FXUS66 KOTX 202354
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
454 PM PDT Thu Aug 20 2026

.KEY MESSAGES...

- A Heat Advisory has been issued for Friday afternoon through
  evening due to very warm temperatures and widespread Major
  HeatRisk.

- Weekend system brings thunder threat and gusty winds,
  resulting in critical fire weather concerns.

&&

.SYNOPSIS...
Temperatures increase well above average by Thursday and Friday
as high pressure dominates. A pattern change Saturday will
bring cooler, unsettled conditions that will result in critical
fire weather conditions through Sunday. Unsettled conditions
will continue into the start of next week.

&&

.DISCUSSION...
Thursday: High pressure continues to build over the Inland
Northwest continues to keep things warm and dry. Temperatures today
will warm into the mid to high 90s, bringing a Moderate chance of
HeatRisk to the Inland Northwest. All those sensitive to heat-
related illnesses should make sure they have adequate access to
cooling and hydration, and some systems and industries will be
impacted. Very warm high temperatures, relative humidity values 12-
20 percent, and sufficient mixing will result in elevated fire
weather concerns over the Cascades, especially for already
established wildfires.

Friday through Sunday: Models finally look to be converging on
timing of an incoming cold front bringing gusty winds and isolated
to scattered thunderstorms to the region. Ahead of the cold front
passage on Saturday, temperatures on Friday warm into the high 90s
with triple digits expected in the lower Basin and Lewiston areas.
This has led to widespread Major HeatRisk values, which indicates
that anyone without adequate cooling and hydration as well as
health systems and industries could see impacts. To reflect
this, a Heat Advisory has been issued for nearly all parts of
the region tomorrow from 11 AM to 10 PM. Additionally, low
temperatures in the 60s and 70s will provide little overnight
relief.

Friday night into Saturday, moisture advection ahead of the frontal
passage will raise PWATs to 125 to 150 percent of normal. On
Saturday into Sunday, the arrival of the cold front reinforced by a
40-50kt 500mb jet and warm overnight and daytime temperatures will
create a favorable environment for isolated to scattered
thunderstorms across the Cascades and northern mountains areas.
While these showers will initially start out as isolated in nature,
as higher PWATs increase in coverage, thunderstorms will become more
scattered in nature, especially into later Saturday morning. With
PWATs near 1 inch and DCAPE values 500 J/kg and higher, main impacts
with these storms look to be heavy downpours, gusty outflow winds
near 40 to 50 mph, and lightning. Steep terrain and burn scars will
need to be monitored for any heavy rainfall rates. This threat will
move eastward across the forecast area through the day, and Saturday
night into Sunday morning the ID Panhandle has the same chances at
seeing isolated to scattered thunderstorms. To reflect these
critical fire weather conditions, Fire Weather Watches have been
issued. For the Cascades and northern mountains, the Fire Weather
Watch has been issued from Saturday morning through Sunday morning.
For the ID Panhandle, a Fire Weather Watch has been issued from
Saturday afternoon through Sunday morning.

Additionally, in the afternoon and evening, winds will increase with
the cold frontal passage, particularly across the Columbia Basin.
There is a 40 percent chance and higher for most locations in the
region to see wind gusts higher than 30 mph on Saturday night. Areas
that will see the highest gusts include the Lewiston, Moses Lake,
Wenatchee, and Waterville Plateau areas. These areas have a 40
percent chance of seeing wind gusts 35 mph or higher. This will
bring critical fire weather conditions to the area. A Fire Weather
Watch has been issued for the basin, Palouse, and Spokane areas from
Saturday afternoon through Saturday evening. Potential impacts from
these winds include rapid spreading of wildfires alongside blowing
objects and difficulties driving, especially for high profile
vehicles.

Initially, models had the low moving out of the area quicker, but
are now in better agreement that the low will linger over the state
of Washington through Sunday before moving out of the area Sunday
night into Monday. This will result in impacts from the cold front
being seen into Sunday afternoon. In the morning, the northern Idaho
Panhandle will continue to see isolated to scattered thunderstorms.
One thing to keep a close eye on is the extent of the thunderstorms
post cold frontal passage on Sunday morning. Some models are showing
enough lingering instability throughout Spokane that it may need to
be added into the Saturday into Sunday Fire Weather Watch.
Additionally, residual wind gusts around 15-20 mph will linger
throughout the Cascade gaps, Okanogan Valley, Waterville Plateau,
Columbia Basin, Spokane/CdA, and Palouse areas through late Sunday
afternoon. These winds will result in continued elevated fire
weather conditions.

A significant cooldown due to the cold front will be observed
Saturday into Sunday, with high temperatures dropping nearly ten
degrees. This cooldown will result in temperatures being a couple
degrees below normal on Sunday. By Sunday evening, precipitation
chances across the region drop down to near zero.

Monday through Wednesday: With high confidence (80 percent of
clusters) indicating a strengthening ridge building over the area
early next week, the temperature drop will be short lived. By
Tuesday, temperatures will again warm into the high 80s to low 90s.
However, long term models and clusters show another trough
approaching the PNW coast, though timing and track are uncertain.
Chances for precipitation remain low, with PoPs 15 percent and
lower expected Monday through Wednesday. /AS

&&

.AVIATION...
00Z TAFs: VFR conditions are expected to continue through the
TAF period. Winds will be diurnally driven and remain less than
10 kts for most locations. Smoke from local wildfires may cause
minor reductions in visibility, especially for Wenatchee,
Chelan, Winthrop, and Omak. Smoke models show EAT remaining at
or below 6SM through the TAF period. For all other terminals,
smoke models show visibilities are expected to remain VFR at 6SM
or greater with areas of haze drifting across Northeastern WA
and North Idaho.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence
in light winds and VFR conditions for all TAF sites. Greatest
uncertainty is visibility for KEAT. Visibility at KEAT was
reduced to 2SM Thursday morning and may need to be adjusted
lower with future forecasts due to increased smoke production
from the Cascade fires this afternoon.


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

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:/www.weather.gov/otx/avndashboard

&&

.Preliminary Point Temps/PoPs...
Spokane        59  97  66  93  57  80 /   0   0  10  10  30   0
Coeur d`Alene  60  98  66  93  58  80 /   0   0  20   0  40  10
Pullman        55  97  59  89  49  77 /   0   0  30  10  20   0
Lewiston       66 103  71  96  62  85 /   0   0  20  10  30   0
Colville       52  96  58  93  50  79 /   0   0  20  10  40  20
Sandpoint      56  94  61  91  53  78 /   0   0  10  10  40  10
Kellogg        58  96  63  91  54  77 /   0   0  20   0  30   0
Moses Lake     59  99  67  93  53  84 /   0   0  10  10  10   0
Wenatchee      69  96  74  92  61  82 /   0   0  20  30  10   0
Omak           64  97  70  95  57  83 /   0   0  10  20  30  10

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
WA...Heat Advisory from 11 AM to 10 PM PDT Friday for Central
     Chelan County-Lower Garfield and Asotin Counties-Moses
     Lake Area-Northeast Blue Mountains-Northeast Mountains-
     Okanogan Highlands-Okanogan Valley-Spokane Area-Upper
     Columbia Basin-Washington Palouse-Waterville Plateau-
     Wenatchee Area-Western Okanogan County.
     Fire Weather Watch from Saturday afternoon through Saturday
     evening for Colville Reservation (Zone 702)-Eastern
     Columbia Basin  -Palouse  -Spokane Area (Zone 708)-
     Foothills of Central Washington Cascades (Zone 705)-
     Foothills of Northeast Washington (Zone 701)-Lower
     Palouse  -Snake River (Zone 709)-Waterville Plateau (Zone
     706)-Western Columbia Basin (Zone 707).
     Air Quality Alert until 10 AM PDT Friday for Central Chelan
     County-Moses Lake Area-Okanogan Highlands-Okanogan Valley-
     Upper Columbia Basin-Waterville Plateau-Wenatchee Area-
     Western Chelan County-Western Okanogan County.
     Fire Weather Watch from Saturday morning through Sunday
     morning 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)-Methow Valley (Zone 704)-
     Okanogan Highlands and Kettle Mountains (Zone 699)-
     Okanogan Valley (Zone 703).
ID...Heat Advisory from 11 AM to 10 PM PDT Friday for Central
     Panhandle Mountains-Coeur d`Alene Area-Idaho Palouse-
     Lewis and Southern Nez Perce Counties-Lewiston Area-
     Northern Panhandle.
     Fire Weather Watch from Saturday afternoon through Sunday
     morning for Northern and Central Idaho Panhandle (Zone
     101).

&&

$$