Chelan Falls, Washington Weather Forecast Discussion

939
FXUS66 KOTX 110611
AFDOTX
Area Forecast Discussion
National Weather Service Spokane WA
1111 PM PDT Wed Sep 10 2025
.KEY MESSAGES...
- Showers and thunderstorms mainly in the mountains, southeast
  Washington, and the Idaho Panhandle this week.
- Areas of smoke and haze through the weekend, especially near
  wildfires.
&&
.SYNOPSIS...
Isolated to scattered showers and thunderstorms across the
region will continue through late week. Areas of smoke and haze
are expected to continue through at least the weekend,
especially near wildfires.
&&
.DISCUSSION...
Tonight through Thursday Night: A closed low over northern
California will continue to produce south-southeast flow across
Eastern WA/N Idaho into Thursday. The low will track into
southeast Oregon on Thursday. The position of the low will favor
the highest shower and thunderstorms coverage over SE
Washington, the Lewiston-Clarkston area, Camas Prairie, and
Central Panhandle Mountains. Surface based CAPE of 500-1000 J/KG
will lead to additional shower and thunderstorm development
through the afternoon across NE Oregon and the Clearwaters, with
the southeast flow tracking some of this activity into SE
Washington the the south ID Panhandle this evening. Convection
is expected to weaken as activity moves into NE Washington and
the N Idaho Panhandle due to further proximity from the low as
well as the loss of daytime heating by the time convection has
a chance to move into these areas. Yet isolated shower and
thunderstorms activity will persist over the area mountains
prior to the loss of daytime heating. On Thursday a near repeat
is expected, except that precipitable water increases further
to near 180% of normal. This will mean the potential for heavier
rainfall with storms. The Weather Prediction Center is carrying
a marginal risk (5% chance at a point within a 25 mile radius)
for flash flooding for all or portions of Whitman, Garfield,
Asotin, Nez Perce, Lewis, Latah, Benewah, Kootenai, Bonner, and
Shoshone counties. Yet the probability of storms producing flash
flooding is too low to issue flood watches at this time given
HREF probabilities of 0.50"/an hour less than 30%, and the
current drought across the region. Other concern with storms on
Thursday is gusty outflow winds. The HRRR, FV3, and ARW models
are generating 25-40 MPH outflow gusts from convection in Idaho,
and propagating these gusts outward over large distances into
the Spokane area and portions of NE Washington that could
influence regional fires.
Friday: The low starts to pull away from the area as a short
wave ridge noses into Central WA. Residual instability is
expected to bring another round of showers and thunderstorms to
the Idaho Panhandle with a 20-30% chance of showers across
Eastern WA.
Saturday through Wednesday: On Saturday an upper ridge is
centered over the region for warm and dry conditions. The
forecast gets more uncertain heading into Sunday and Monday with
an upper trough that approaches and where it goes. Roughly half
of the ensembles develop a closed low and track it south of the
area for little if any precipitation for Eastern WA/North ID.
The other half either hold the trough together, or develop a
closed low over the area for cooler temperatures and
precipitation. At this time the NBM is going for a 20-40% chance
of showers and subtle cooling. On Tuesday and Wednesday
indications are that an upper ridge again builds for warmer and
drier weather.
Smoke/haze: Air Quality Alerts issued by the Department of
Ecology remain in effect until further notice for Chelan, Ferry,
Stevens, and Pend Oreille counties. Precipitation over these
counties is expected to be spotty this week with any
precipitation isolated in nature. This will likely allow for
continued active smoke production from wildfires. The situation
could improve early next week if the cooler/wetter scenario
plays out Sunday/Monday but as mentioned above confidence is
low. JW
&&
.AVIATION...
06Z TAFS: As of 06Z, an outflow boundary propagating off an
area of showers across southeast Washington and the southern
Idaho Panhandle is moving west-northwest across Whitman County
and southeast Spokane County. New shower and isolated
thunderstorms are developing along the boundary. Included a
tempo group for GEG/SFF for this boundary to bring an brief
increase in the winds with gusts around 25-27 knots as it moves
through. For Thursday, another round of convection will develop
with in the afternoon with the highest potential for
thunderstorms near the Lewiston area and east of Coeur d`Alene.
Conditions are expected to remain VFR.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
The chance for thunderstorms for the TAF sites Thursday
afternoon is 30% KLWS/PUW, and 20% KGEG/KSFF/KCOE.
-----------------------
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        58  84  57  82  56  83 /  10  20  20  20  20  10
Coeur d`Alene  59  84  57  80  56  82 /  20  30  30  20  20  20
Pullman        53  77  52  76  51  78 /  50  30  50  40  30  20
Lewiston       62  83  61  82  61  85 /  60  40  60  40  30  20
Colville       46  87  46  83  47  83 /   0  10  10  20  20  20
Sandpoint      53  83  51  78  51  79 /  10  30  30  40  30  30
Kellogg        59  81  57  76  58  77 /  40  50  60  50  50  40
Moses Lake     56  85  55  84  54  84 /  10  10  10  10   0   0
Wenatchee      64  87  62  85  60  84 /   0  10  10  10   0   0
Omak           60  91  58  88  58  86 /   0  10  10  10  10   0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
WA...Air Quality Alert until further notice for Central Chelan
County- Northeast Mountains-Okanogan Highlands-Wenatchee Area-
Western Chelan County.
ID...None.
&&
$$

NWS OTX Office Area Forecast Discussion