Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
704
FXUS66 KSEW 212216
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
316 PM PDT Tue Apr 21 2026
.SYNOPSIS...
A return to cooler and cloudier conditions as showers rotate
through the region around an upper low to the south. Isolated
thunderstorms are possible this afternoon in the Cascades. Drier
and warmer conditions return late in the week through next
weekend with a stronger ridge of high pressure building
offshore.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
An upper low remains positioned off of southern Oregon and
northern California, spreading increasing cloud cover and mid
level moisture across the region. We`ll see continued showers
across the region, with increasing coverage across Western
Washington. This will bring temperatures down to considerably
cooler values than the last few days. With increasing
instability this afternoon, we`ll have the potential for a few
isolated thunderstorms across the Cascades through the evening
hours. Little change to the pattern into Wednesday as the upper
low slowly progresses eastward across the western U.S.
Temperatures remain on the cooler side, toping out mostly in the
upper 50s tomorrow. Moving into Thursday, heights begin to rise
on the back side of the system as the upper low drifts further
eastward. This will have the impact of both cutting off support
for additional showers and bring about another warming trend as
clouds begin to decrease.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
Ensemble guidance remains in good agreement for a return of high
pressure over the region late in the week. This should bring a
return of Minor HeatRisk as temperatures again climb into the
upper 60s to near 70 in the warmest locations. However, the
location of the ridge axis - specifically, how far offshore or
over the region it remains - remains a key bit of uncertainty in
the forecast with a decent amount of spread. This could leave
the door open to the opportunities for some light showers late
in the weekend or early next week with a few embedded impulses
rotating within the flow across the region
&&
.AVIATION...
South to southeasterly flow aloft will turn east to northeasterly
tonight as a broad upper trough moves onshore over northern
California and southwest Oregon. The low level flow is onshore.
Ceilings will deteriorate late this afternoon as moisture associated
with the area of low pressure spreads northward into the region.
MVFR ceilings in scattered showers are expected most areas by
this evening with shower coverage increasing overnight.
Predominantly MVFR ceilings in showers will persist into Wednesday
with minor improvement late in the day as shower activity
diminishes.
KSEA...Ceilings on are track to deteriorate late this afternoon as a
band of deeper moisture lifts northward into the area. MVFR ceilings
in showers this evening will continue into Wednesday morning with
improvement to low end VFR expected near or after 00Z Thursday.
Surface winds S/SW 8 to 12 knots this afternoon/evening will
increase Wednesday morning to 10 to 15 knots gusting to around 20
knots at times.
27
&&
.MARINE...
Weak low pressure will remain over the inner coastal and interior
waters into Thursday with broad high pressure remaining well
offshore for an onshore flow pattern. The flow will turn more
northerly over area waters Friday into Saturday with a broad surface
ridge over the western Canadian provinces and lower pressure over
the Pacific Northwest.
Small craft advisories remain in effect for the central/east strait
today and for the coastal waters and Puget Sound tomorrow. Seas will
build and steepen over the coastal waters on Wednesday with seas
nearing rough bar criteria at Grays Harbor by Wednesday night. Seas
will then gradually subside later Thursday into the weekend.
27
&&
.HYDROLOGY...
No river flooding is expected during the next seven days.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 11 PM PDT this evening for Central
U.S. Waters Strait Of Juan De Fuca-East Entrance U.S.
Waters Strait Of Juan De Fuca.
Small Craft Advisory from 11 AM Wednesday to 11 AM PDT
Thursday for Coastal Waters From Cape Flattery To James
Island 10 To 60 Nm-Coastal Waters From Cape Flattery To
James Island Out 10 Nm-Coastal Waters From James Island
To Point Grenville 10 To 60 Nm-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