Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
053
FXUS66 KSEW 210344
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
844 PM PDT Mon Apr 20 2026
.SYNOPSIS...Cooler temperatures and increased chances for
precipitation arrives Tuesday through midweek. Warmer and drier
conditions look to return later through the week and into the
weekend.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...Mid and high
clouds are increasing across Western Washington this evening
associated with an upper low offshore of Oregon/California.
Generally dry conditions tonight with showers increasing on
Tuesday. No major forecast updates this evening, previous
discussion below.
A deep upper level low continues to meander offshore and will
shift further inland on Tuesday, allowing for wrap around
moisture to move into western Washington. This will allow for
showers to move northward throughout the area on Tuesday and for
cooler temps in the upper 50s and lower 60s. There will also be
instability from the aforementioned upper level low, so we could
see some isolated thunder Tuesday afternoon/evening, but mainly
confined to the Cascades. Snow levels will remain above 5000 to
6000 feet with minimal accumulating snow over the higher peaks.
This trend continues into Wednesday with scattered showers
across most of the area and high temperatures in the mid 50s.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...Shower activity will
decrease heading into Wednesday night as an upper level ridge
develops offshore. Ensemble guidance shows a warming and drying
trend through the end of the week and heading into the weekend,
with temperatures warming back up into the upper 60s and
potentially low 70s. Models do show some disagreement on the
strength of the ridge and how long the conditions remain dry
for.
Mazurkiewicz
&&
.AVIATION...Southerly flow aloft will continue into Tuesday as
a cutoff upper level low off the northern California coast
gradually shifts eastward. A combination of developing low level
onshore flow and moisture wrapping around this system will lead
to increasing shower activity along with lowering ceilings
across the area on Tuesday. Ceilings are expected to lower to
MVFR along the coast overnight then spread northward across
interior areas Tuesday morning. These conditions will then
persist into Tuesday night and beyond.
KSEA...VFR conditions will continue into this evening. Ceilings will
lower overnight and are expected to become MVFR by around mid-
morning Tuesday with showers in the vicinity of the terminal by
afternoon. Surface winds will become S/SW 4 to 8 knots with gusts
near 15 kt tonight and continue overnight. Winds will rise to 10 to
15 knots at times Tuesday morning. 27/41
&&
.MARINE...Weak low pressure will remain over the inner coastal
and interior waters into midweek with broad high pressure
remaining well offshore. A modest increase in onshore flow on
Tuesday is expected to produce small craft advisory winds in the
central and east portions of the strait. Gusty north to
northwesterly winds and steepening seas are expected over the
outer coastal waters on Wednesday. Winds ease, seas subside and
the flow turns more northerly late this week in response to a
strengthening surface ridge over British Columbia. 27
&&
.HYDROLOGY...No river flooding is expected over the next 7 days.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 3 PM to 11 PM PDT Tuesday for
Central U.S. Waters Strait Of Juan De Fuca-East Entrance
U.S. Waters Strait Of Juan De Fuca.
&&
$$
NWS SEW Office Area Forecast Discussion