Clarkston, Washington Weather Forecast Discussion

984
FXUS66 KOTX 252313
AFDOTX
Area Forecast Discussion
National Weather Service Spokane WA
413 PM PDT Thu Sep 25 2025
.KEY MESSAGES...
- Vigorous dry cold front passage Thursday afternoon/evening
  with windy and dry conditions resulting in critical fire
  weather conditions.
- Winds may also produce blowing dust across the Waterville
  Plateau into the Columbia Basin Thursday afternoon.
- Patchy frost for northern mountain valleys and northern
  Panhandle overnight Thursday and Friday.
&&
.SYNOPSIS...
Windy conditions and very low RHs are expected with a cold
front passage late Thursday afternoon and evening. The
combination of gusty winds and dry conditions will lead to
critical fire weather conditions across much of central and
eastern Washington. Chilly mornings Friday and Saturday before
temperatures see a bump up above normal over the weekend. Cooler
temperatures and chances for showers by early next week.
&&
.DISCUSSION...
Thursday: A fast-moving cold front and associated trough is pushing
into western Washington early this afternoon and will continue
swiftly east through the Inland Northwest later this afternoon and
evening. This system will bring dry and gusty westerly winds. Ahead
of the front, southwest winds are already increasing with relative
humidity values in the low teens across central Washington. The
strongest winds are expected in the lee of the Cascades as the
front moves through with winds decreasing though remaining
gusty across the Columbia Basin, and extending into the Spokane
area and Palouse. As of 12 PM, the PDX-GEG pressure gradient was
+8 mb, with values projected to rise to +11-12 mb. This will
support sustained winds of 15-30 mph with gusts of 30-45 mph
late this afternoon into the evening. A few light showers (15%
chance) will be possible over the northern mountains with the
frontal passage, but otherwise this will be a dry front with
PWATs dropping to 0.30-0.40 inches as much drier air aloft mixes
to the surface. The main impacts will be rapid fire spread
potential with any new starts and areas of blowing dust near
recently plowed fields.
A secondary concern will develop this evening into the early
overnight hours across the Cascades and east slopes as a
northwest- to- southeast oriented jet streak shifts into
Washington behind the upper trough. Strong westerly flow over
the terrain combined with a stable layer near ridge tops will
favor mountain wave activity. While an overnight surface
inversion will keep lower valley winds lighter, exposed ridges
may experience continued gusty winds tonight.
Friday through Wednesday: Broad zonal flow will set up across the
Pacific Northwest on Friday following the cold frontal passage. Dry
air and clearing skies Thursday night into Friday will allow for a
chilly start Friday morning, with afternoon highs 5-10 degrees
cooler than Thursday (upper 60s to mid-70s). Over the weekend, the
Inland Northwest will sit on the western side of an amplifying ridge
over the central US in response to a deepening trough over the
eastern Pacific and a low moving into the Gulf of Alaska.
Temperatures will rebound into the upper 70s to 80s through Sunday.
From Sunday night into midweek, ensemble guidance is in general
agreement that the leading upper-level trough will move onshore
the PNW, followed by a weaker version of the Gulf of Alaska
low. Forecast confidence is high that temperatures will cool
with increasing precipitation chances across the Inland
Northwest. Between 5 AM Monday and 5 AM Thursday, there is a
>70% chance of at least 0.25 inches of precipitation across the
Cascades, northern mountains, Idaho Panhandle mountains, and
Camas Prairie. Probabilities are 50- 70% for the northern
Washington and Idaho Panhandle valleys, Spokane area, Palouse,
and L-C Valley, decreasing to 15-30% over the Columbia Basin,
Waterville Plateau, and near Wenatchee. For the larch marchers,
NBM guidance also supports snow levels lowering to 6500-7000
feet over the Cascades Monday night through Wednesday, which
could bring snow to the higher peaks. Stay tuned! /vmt
&&
.AVIATION...
00Z TAFS: A cold front currently located near the Cascades will
push through the Inland Northwest over the next few hours. Breezy
southwest to west winds are currently being observed ahead of
the front and will shift to the west northwest behind the front.
Wind gusts of 20-30 kts are forecast across the region during
the afternoon and evening. Strong westerly winds aloft over the
Cascades will favor mountain wave development through the
evening, potentially leading to gusty winds up to 45kts over the
east slopes of the Cascades.
Fires in the Cascades have become more active today with
visibilities dropping to 5-6SM for KEPH/KGEG/KSFF and even down
to 2.5SM for KMWH. I would expect these to clear up over the
next couple of hours as winds pick up, though visibilities down
to 6SM around KEAT/KMWH/KEPH will continue tomorrow. The winds
will also kick up areas of blowing dust across the Columbia
Basin. West winds could lead to reduced visibility at
KMWH/KGEG/KSFF/KPUW this afternoon from a combination of
wildfire smoke and blowing dust. Otherwise skies are expected to
be clear for most of today, before a band of passing mid and
high clouds with the front.
FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
High confidence for gusty winds with the cold front passage.
There is moderate confidence for localized MVFR conditions to
continue around KMWH and intermittent MVFR conditions KGEG/KSFF
for the next couple of hours from smoke and dust. There is low
confidence in wind gusts up to 45kts for the lee of the
Cascades.
-----------------------
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        44  69  46  76  50  82 /   0   0   0   0   0   0
Coeur d`Alene  45  69  45  75  50  82 /   0   0   0   0   0   0
Pullman        41  66  42  76  48  79 /   0   0   0   0   0   0
Lewiston       51  72  49  81  54  84 /   0   0   0   0   0   0
Colville       35  71  37  73  38  78 /  10   0   0   0   0   0
Sandpoint      41  67  40  71  45  78 /  10   0   0   0   0   0
Kellogg        46  66  47  77  55  81 /   0   0   0   0   0   0
Moses Lake     42  73  45  77  46  79 /  10   0   0   0   0   0
Wenatchee      51  74  54  77  55  78 /  10   0   0   0   0   0
Omak           43  73  50  76  50  78 /  10   0   0   0   0   0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
WA...Red Flag Warning until 11 PM PDT this evening for Colville
     Reservation (Zone 702)-East Portion of North Cascades
     National Park/Lake Chelan National Recreation Area (Zone
     697)-East Washington North Cascades (Zone 698)-Eastern
     Columbia Basin  -Palouse  -Spokane Area (Zone 708)-
     Foothills of Central Washington Cascades (Zone 705)-Lower
     Palouse  -Snake River (Zone 709)-Methow Valley (Zone 704)-
     Okanogan Valley (Zone 703)-Waterville Plateau (Zone 706)-
     Western Columbia Basin (Zone 707).
     Air Quality Alert until noon PDT Friday for Central Chelan
     County-Okanogan Highlands-Okanogan Valley-Waterville
     Plateau-Wenatchee Area-Western Chelan County-Western
     Okanogan County.
     Red Flag Warning until 9 AM PDT Friday for East Washington
     Central Cascades (Zone 696).
ID...None.
&&
$$

NWS OTX Office Area Forecast Discussion