Longmire, Washington Weather Forecast Discussion

037
FXUS66 KSEW 240335
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
835 PM PDT Tue Sep 23 2025
.SYNOPSIS...High pressure will persist over western Washington
through mid-week, with periods of degraded air quality from
wildfire smoke. Flow towards the end of the week will become
zonal, promoting onshore flow with seasonal temperatures and
dry conditions. Chances for widespread rainfall increase into the
weekend, with a pattern change to wetter and cooler conditions by
next week.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY/...Air Quality Alerts are in
effect for King and Snohomish county due to wildfire smoke and
degraded air quality. However, we should see improving conditions
with onshore flow on Wednesday. Overnight lows in the upper 40s to
mid 50s look on track. 33
Previous discussion...As high pressure persists over the Pacific
Northwest and a thermal trough develops northward along the coast,
flow at the surface has turned offshore. Easterly to
southeasterly winds through the Cascades has brought areas of
dense wildfire smoke to the western Cascades and lowlands east of
the Puget Sound this afternoon, causing areas of degraded air
quality. Areas of smoke will continue to linger through early
Wednesday under weak flow. Temperatures today are on track to peak
in the mid to upper 70s across the lowlands, and in the upper 60s
along the water.
Flow will begin to flatten on Wednesday as a disturbance traverses
inland over British Columbia. This will promote onshore flow by
the afternoon, bringing in slightly cooler air and additional
clouds to western Washington. The westerly flow will also help to
scour out the wildfire smoke to the east of the Cascade Crest.
Zonal flow on Thursday and Friday will bring increased onshore
flow, with a return of cloudy skies and high temperatures mostly
in the 60s. While forecast models start to show differing
solutions on Friday, ensembles maintain a slight chance of light
showers over the northern portions of western Washington.
.LONG TERM /SATURDAY THROUGH TUESDAY/...Chances for more
widespread rainfall increase throughout the weekend as an upper
level low deepens over the Gulf of Alaska and slowly traverses
southward. While chances for rain increase on Saturday, ensembles
are in better agreement over bringing in the bulk of the incoming
moisture on Sunday, with unsettled and wet conditions continuing
into next week. This will likely bring a few rounds of beneficial
rainfall to western Washington alongside near normal temperatures.
15
&&
.AVIATION...Southwest flow aloft will transition more westerly as
the upper ridge flattens into Wednesday. VFR conditions this evening
with a few high clouds. Haze/smoke continues as well this evening,
primarily aloft for most TAF sites. There remains slight chance of
fog development early Wednesday morning, mainly around KOLM. Any
stratus development along the coast is expected to be limited as
well. Otherwise, VFR with a few high clouds through Wednesday. Light
winds tonight will increase from the N/NW on Wednesday afternoon.
KSEA...VFR conditions through Wednesday with mainly clear skies.
Haze likely into tonight, but not expected to lead to visibility
issues. N/NE surface winds of 5 to 10 kts tonight increasing from
the NW on Wednesday. JD
&&
.MARINE...A thermally induced trough will shift inland tonight.
Onshore flow will begin to increase late Wednesday and continue
through the rest of the week. Northerly winds will increase for the
Coastal Waters through Thursday. A Small Craft Advisory has been
issued for the central and southern inner Coastal Waters, as well as
the outer southern Coastal Waters this evening due to increased
northerly winds. In addition, will need to monitor the potential for
further SCA winds over the Coastal Waters Wednesday into Thursday.
Combined seas 6 to 8 feet decreasing to 5 to 7 feet on Thursday.
Seas look to gradually build back upwards, potentially over 10 feet
into the weekend.
JD/Mazurkiewicz
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until midnight PDT tonight for Coastal
     Waters From James Island To Point Grenville Out 10 Nm-
     Coastal Waters From Point Grenville To Cape Shoalwater 10
     To 60 Nm-Coastal Waters From Point Grenville To Cape
     Shoalwater Out 10 Nm.
&&
$$

NWS SEW Office Area Forecast Discussion