Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
407
FXUS66 KSEW 091554
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
854 AM PDT Fri May 9 2025
.SYNOPSIS...Dry and relatively warm weather today. The pattern will
begin to shift overnight setting the stage for a cooler, showery
pattern for much of the weekend. A more organized frontal system
looks to bring more widespread rain later Sunday into Monday. Upper
level ridging will affect the area by midweek with active weather
returning at the end of next week.
&&
.SHORT TERM /TODAY THROUGH SUNDAY/...No significant changes made
to the forecast this morning. The previous discussion can be found
below along with an update to the aviation section:
Latest satellite imagery this early morning shows high clouds
moving across W WA, although patchy enough to allow some peeks of
sky through. Thicker high clouds more prevalent to the north and
west associated with an incoming upper level trough. Still, this
leaves the upper level ridge holding court over much of the
western US in the driver seat for the CWA, continuing dry
conditions and giving temps a shot in the arm. Highs today mainly
in the mid 60s to around 70...although water adjacent locations
will be a touch cooler with highs in the upper 50s to lower 60s.
The aforementioned trough will start to shift eastward slowly
overnight, bringing increasing clouds this evening and tonight.
Leading edge of moisture starts to make its way to the coast early
Saturday morning, however models struggle to bring any meaningful
precip into much of W WA. That said, it does look like the best
chances will be along the coast and, due to the southwest to
northeast orientation of this band of moisture, portions of western
Whatcom and Skagit counties.
Instead, more convincing precip will have to wait until the trough`s
parent low dips southward overnight Saturday, bringing a more
organized front to the coast by early Sunday morning. As this upper
low continues to plunge southward, it will continue to cycle
moisture up into W WA and thusly will keep much of the day cool and
showery. Deterministic models and ensembles in good agreement here
in making Sunday the best chance for precip in the near term, even
though PoPs hover around 50-ish percent and QPF values remain
generally unimpressive...with ensemble mean generally at 0.05 of an
inch or less. One last point of interest with Sunday, NBM had
suggested 24 hours ago the possibility for some late afternoon/early
evening thunderstorms...although deeper analysis of expected
instability really did not lay a good foundation for that prospect.
It appears the blended model has caught on to this, retreating and
eliminating the prospect from the forecast. Will continue to monitor
as Sunday draws closer.
High temps this weekend will be cooler than those expected today,
although still falling in what one would consider spring-like,
generally ranging in the lower to mid 60s, although water adjacent
locations will have a hard time getting out of the mid to upper 50s.
18
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...A little more of a consensus
in the model data, taking the upper low down to the OR coast before
starting to shift it eastward. This will keep enough moisture over W
WA for showers to linger into at least Monday morning before drying
from west to east occurs during the afternoon. Generally dry
conditions expected to return over much of the area Monday night,
with the only exception being over the Cascades.
A weak upper level ridge starts to shift into W WA Tuesday to keep
much of the CWA dry. However, this feature is not expected to be
strong enough to push out the precip over the Cascades nor to
eliminate occasional nuisance PoPs /generally 15 pct or less/ from
the forecast. As the feature lingers into Wednesday, so too do
similar conditions. Consensus breaks down going into Thursday, as
deterministic models cannot agree on the timing of the next system.
The ECMWF is more agressive, bringing in a frontal system that day
while the GFS actually strengthens the ridge before bringing the
front in Friday. Given the uncertainty, not surprising that both
ensembles and NBM split the difference, bringing some PoPs in for
the day, however keeping them pretty limited /10-30 pct/ to
highlight the uncertainty.
Daytime highs remain largely static throughout the long term,
generally mid to upper 50s near the water, lower to mid 60s inland.
Tuesday appears to be the warmest with most interior spots in the
mid 60s and water adjacent locations favoring upper 50s to around 60.
18
&&
.AVIATION...An upper ridge is located over the Southwest with
southwest flow continuing across Western Washington. VFR cigs will
continue through tonight with high clouds. Cigs will slowly lower
along the coast later tonight with a few showers possible by
Saturday morning along the Olympic Peninsula. Light N/NW winds
today, will become more S/SW on Saturday.
KSEA...VFR cigs with high clouds. NW winds will increase towards 6
to 10 kts this afternoon. Winds will then shift to S/SW Saturday
morning. JD
&&
.MARINE...Mainly light winds over the waters today with surface
high pressure. A weak frontal system will move inland on Saturday,
for stronger onshore flow. A surface low will pass to our south
Sunday and Monday, with northerly flow over western WA. Seas build
over the outer Coastal Waters on Tuesday to over 10 ft. 33
&&
.HYDROLOGY...The daily hydrology discussion has ended until the
start of the next rainy season; it will only be included as needed.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.
&&
$$
NWS SEW Office Area Forecast Discussion