537
FXUS66 KOTX 210632
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
1132 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.

- Saturday system brings increased chances for showers,
  thunderstorms, and gusty winds. This will lead to critical
  fire weather conditions across the Inland Northwest.

- Patchy blowing dust is possible in the Western Columbia
  Basin.



&&

.SYNOPSIS...
Temperatures will very warm today with increasing mid and high
clouds. A pattern change overnight into Saturday will bring
cooler, unsettled conditions with chances for showers,
thunderstorms, and gusty winds. Sunday will remain breezy but
cooler and continued dry. Next week will be warmer to start the
week with breezy conditions returning midweek.

&&

.DISCUSSION...
Today: The ridge axis that was over the Inland NW on Thursday
will begin to shift eastward into the Idaho Panhandle as a deep
low wobbles toward the WA Coast. This will allow an influx of
mid and high level moisture to drift northward into the region
bringing filtered sunshine. Temperatures will remain warm
topping out in the mid to upper 90s with with some areas
potentially reaching the century mark. The air mass will support
warmer temperatures than Thursday but the presence of high
clouds does add a decent amount of uncertainty exactly how warm
conditions will be. Winds will be light with a moderate amount
of terrain influence. Areas which experience northeast to east
winds could see periods of breezy conditions near 10 mph due to
the alignment with the general winds as they begin to be
influenced by the approaching low pressure system.

Overnight into Saturday night: The low continues to drift toward
the coast overnight and into Western WA on Saturday. A weak
impulse moving out ahead of the low will come through the region
bringing an increased risk for elevated showers or sprinkles.
Some hi-res models indicate a small threat (5-10%) chance for a
few lightning strikes but this comes with very low confidence
due to 850-300mb CAPE only on the order of 50-100 J/kg and very
weak forcing. HREF also advertises near zero probabilities for
lightning overnight, a model that has done well through the
course of the summer. HRRR on the other hand, has some threat as
do a few other hi-res models so it will be something to monitor
given its high based nature and little to no rainfall
associated with it.

As we head into Saturday, the weather becomes a bit more dynamic
as stronger lift arrives. At this time, the way things are
starting to evolve come in different waves. First will be the
threat for showers and thunderstorms along the Cascades Saturday
morning with some activity lingering near the Canadian border
in the afternoon. Second will be showers and thunderstorms
developing over the Idaho Panhandle and extreme southeastern WA
Saturday afternoon and continuing in different waves overnight.
Both areas have the potential for isolated strong storms with
the higher threat leaning toward the Idaho Panhandle given the
activity aligning with peak heating. Gusty outflow winds,
lightning and fire starts, and brief downpours of rain and hail
will be a concern with an cells.

In between these thunderstorm areas, the major concern will be
critical fire weather conditions from gusty winds and hot, dry
conditions. An index used for this is the hot, dry, windy index
which is showing areas of the Columbia Basin well into the 95th
percentile. There is reasonable agreement amongst the models for
a surface low to deepen over NE WA or close to the Canadian
border as the low is drifting inland initially pulling south
winds across the Western Basin and into the Okanogan Valley then
starting to spread eastward while shifting to the southwest as
the low begins to track east and cooler air floods inland
dragging a cold front through. Winds across the East Slopes will
largely follow the footprints of the terrain and come from the
west/northwest. Strongest winds on Saturday look to setup across
the Western Columbia Basin and into the Okanogan Valley where
sustained speeds will be closer to 20-25 mph with gusts of 30-35
mph. The Spokane Area and foothills of the northern mountains
will be windy, but speeds look to be a few mph lighter with
speeds of 15-20 mph and gusts to 30 mph. The strongest winds for
the Eastern Basin, Palouse, L-C Valley, and foothills of the
Blue Mountains will arrive later in the day and into the evening
as the cold front presses through and would not rule out gusts
close to 35 mph when this occurs. Overall, it looks to be a very
impactful day in regards to fire weather for new starts and
wind driven fires. We will also need to watch for blowing dust
on Saturday around Moses Lake, Ritzville, Wilbur, and Omak.

While lightning may be limited across the northern mountains
during the day as the winds are blowing, the low will move
through northern WA and into southern BC Saturday night into
Sunday. This will keep the threat for showers and thunderstorms
going well into the evening and overnight hours while winds
remain elevated region-wide. The main threat for thunderstorms
on Sunday will be in the morning with the system departing to
the east and breezy winds becoming the most impactful weather
through the day while temperatures cool back into the 80s.

Monday through Friday: The pattern is setting up to be quite a
roller coaster and has plenty of support from the ensemble
suites. High pressure moves in Monday and Tuesday promoting a
warming and drying trend. This is quickly interrupted by another
robust shortwave Wednesday. The exact depth and track of this
through the NW comes with some uncertainty but pattern
recognition would suggest another bout of windy conditions and
possibly some thunderstorms. The pattern repeats itself again
Thursday and Friday with the next system Friday into Saturday.
We are not seeing a lot of signs for appreciable rainfall with
these systems indicating fire weather concerns will remain
elevated or higher as we navigate the end of August. /sb

&&

.AVIATION...
06Z TAFs: VFR conditions are expected to continue through the
TAF period though thickening mid and high clouds will be moving
in from the south with cigs varying from 15-20k ft AGL. A weak
northeast pressure gradient will result in elevated winds for
KCOE and KPUW for a few hours in the morning 14-18z with speeds
near 10kts, otherwise winds will be light and less than 10 kts
for most locations. Smoke from local wildfires will bring the
potential for 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 hit similar restrictions
if the upstream smoke gets drawn down the river drainage. Given
the low confidence, forecast is a optimistic to remain around
4SM or higher at this time. /sb


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

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        94  59  97  66  94  59 /   0   0   0  10   0  30
Coeur d`Alene  93  60  98  67  95  60 /   0   0   0  10   0  40
Pullman        93  55  98  60  90  51 /   0   0   0  20  10  30
Lewiston       99  66 103  72  98  64 /   0   0   0  20  10  20
Colville       93  52  96  58  93  52 /   0   0   0  10  10  30
Sandpoint      90  56  94  62  92  55 /   0   0   0  10  10  40
Kellogg        91  58  96  63  92  55 /   0   0   0  10  10  40
Moses Lake     95  59  99  68  94  55 /   0   0   0  10  10  10
Wenatchee      95  69  97  75  92  62 /   0   0   0  10  30   0
Omak           95  64  98  71  95  59 /   0   0   0  10  20  20

&&

.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).
     Air Quality Alert until 3 PM PDT Friday for Lewis and Southern
     Nez Perce Counties-Lewiston Area.

&&

$$