Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
025
FXUS66 KSEW 252226
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
326 PM PDT Thu Jun 25 2026
.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 surface obs show VFR conditions largely across much of
the interior and Puget Sound, except for lingering low ceilings
at KBFI. Starting to see underneath high clouds with satellite
that shows some holes and lingering mid clouds with high-end
VFR ceilings. Elsewhere, low clouds persist along the coast
with radar mosaic showing an area of showers moving soon onto
the coast over the next hour. Little to no improvement in flight
categories anticipated in the coast and western Olympics with
the oncoming rain. Current thinking IFR coast with potential for
LIFR late tonight/early tomorrow. Sound and south interior
terminals expected to see showers move in between 03-06Z.
Meantime, southerly flow regime will largely prevail, except for
KCLM where winds will be light and variable.
KSEA...VFR conditions in place with northeast winds currently
switching back to southwest rest of this afternoon. Latest
ACARS soundings show deep saturation around 8-15 kft AGL with
large scale ascent spreading in. Going forecast on track with
the best chances for showers between 4-6Z with ceilings
anticipated to deteriorate down to MVFR becoming low-end MFR
(less than 2kft) by early morning. Gusts removed from the
forecast based on trends and latest guidance with lower
confidence in gusts greater than 17 kts this afternoon
(confidence under 30%). Elevated west/southwest winds expected
rest of tonight into tomorrow.
ET
&&
.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