Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
438
FXUS66 KSEW 260412
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
912 PM PDT Thu Jun 25 2026
.UPDATE...
Widespread showers are pushing across W WA this evening. Hi-Res
guidance has this activity maintaining overnight into Friday as
a frontal system works its way throughout the region. Notably,
this is the first measurable precipitation the area has observed
in a couple of weeks. For tonight, minimum temperatures are
forecast to range throughout the 50s. The previous discussion
remains below along with an updated aviation section:
&&
.SYNOPSIS...
A weakening front will move into the coast of WA this
afternoon/early tonight before progressing inland early Friday.
The general flow will shift from south to west-northwest by
tomorrow afternoon as a surface low evolves east into British
Columbia. The upper low prompting the current pattern change is
forecast to dive south to Vancouver Island tomorrow moving then
more over the Pacific NW Saturday keeping conditions cool and
unsettled. This upper low and associated trough will shift
slowly east into the Northern Intermountain West on Sunday as
upper-level high pressure builds well offshore. Meantime,
surface high pressure will build this weekend reinforcing
northwest flow.
&&
.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
A warm front is currently moving onshore with the latest water
vapor imagery showing a shortwave trough diving east offshore the
OR/WA border. This feature will continue to track to southwest
OR tonight and is promoting showers. The latest radar display
shows showers moving into the Olympics that will become more
widespread tonight across the interior. Meantime, the upper
low`s main shortwave trough will dive to Vancouver Island
tomorrow reinforcing the unsettled weather with additional large
scale forcing for ascent.
Modest lightning chances exist tomorrow afternoon focused
across the northern Olympics and central/northern slopes of the
WA Cascades. Confidence currently low owing to forecast sounding
showing shallow instability with limited tap into -10C and
colder supporting lightning/ice development. This matches
current thinking with chances 15-20% at this time. Precip
chances will be lowest across the non-mountain areas of the
southern interior tomorrow as chances start tapering off in the
afternoon. Otherwise, reinforcing cooler air mass on Friday will
see highs drop another 2-6 degrees. The cooler air mass will
continue to prevail Saturday under cloudy skies and precip
chances before chances start to wane Saturday night.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
Unsettled weather will persist Sunday into the new week as
upper-level troughing dominates the weather pattern overhead
with an upper-level ridge in the eastern North Pacific.
Synoptic northwest flow with embedded lows/upper disturbances
moving through early-mid week will keep conditions largely
reading few-several degrees below normal with lows near normal
early-mid week. Overall limited sensible weather concerns
beyond repeated chances for rain in the mountains, lower chances
in the non-mountain areas.
&&
.AVIATION...
Latest mosaic radar shows bands of rain showers moving across the
southern edge of Puget Sound with another band forming along the
coast. Intermittent rain shower activity will continue through
the night. MVFR conditions will develop for the interior terminals
with 10-20% chances of IFR ceilings between 12z and 15Z. Coastal
terminals have 50-80% chances of IFR conditions (and 10-15% of LIFR)
until 18Z Friday. Models show the bulk of rain shower activity
waning down by 12Z Friday. There are 15-20% for thunder for
from KPAE north and east to the Cascades between 18Z Friday and 06Z
Saturday. Southerly winds will largely prevail, except for
KCLM where winds will be light and variable.
KSEA...VFR conditions in place then transitioning to the low end of
MVFR with ceilings less than 2k ft after 05Z. Light rain showers
will continue on and off through the night period. MVFR conditions
expect to return between 18Z and 20Z. Southerly winds will
continue with the elevated winds during the afternoon
period.
&&
.MARINE...
Complex MSLP pattern over the next 24-hrs with increasing
surface pressure differences late Friday as surface high
pressure builds well offshore with surface low pressure inland.
This will promote gusty northwest winds by late Friday
continuing through Friday night, highest winds across the Juan
de Fuca. Meantime, outer coastal water wave heights will trend
upward to 7-9 ft. Otherwise, low chances for embedded isolated
thunderstorms tomorrow over the coastal waters (10-15%) as a
front moves through Friday. Onshore flow regime continues this
weekend with increasing wave heights Saturday-Sunday building
to 10-12 feet by Saturday night.
&&
.FIRE WEATHER...
Fire weather concerns revolve around a marginal lightning threat
tomorrow. Current thinking is there remains a low risk (15-20%)
for embedded isolated thunderstorms capable of infrequent CG
lightning. Main areas of fire weather concern will be focused on
lee-side of Olympics and areas that dont get any initially
wetting rain after the hot, dry spell. Otherwise, cool and
unsettled conditions prevail Saturday with elevated afternoon
humidity expected over the next 7-days alongside a very low
lightning risk.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 3 PM Friday to 2 AM PDT Saturday 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