Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
881
FXUS66 KSEW 131719
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
1019 AM PDT Wed May 13 2026
.SYNOPSIS...
Upper level low moving inland south of the area this morning.
Air mass behind the low remaining unstable enough to keep
showers in the forecast into Thursday morning. Weakening front
moving through Thursday night with an upper level trough
following the front Friday. Unsettled weather continuing into
Saturday. Upper level ridge centered offshore Sunday through
Tuesday with a weak system trying to move over the top of the
ridge Monday.
&&
.SHORT TERM /TODAY THROUGH FRIDAY/...
Satellite imagery shows cloudy skies over Western Washington
early this morning with an upper level low near Coos Bay/North
Bend Oregon. Doppler radar indicating precipitation from the
Puget Sound eastward and along the central coast. Mild early
morning with the rain and cloud cover keeping temperatures in
the 50s. Seattle-Tacoma airport did get 0.01 inches of rain
Tuesday breaking a 13 day dry streak. It was only the 12th day
with measurable rain in Seattle since the first full day of
spring ( March 21st ). The normal number of rain days during
this time frame is 25.
Upper level low will weaken and move east today leaving an upper
level trough over Western Washington. Showers continuing this
morning decreasing this afternoon. The rain, cooling of the air
mass and weakening of the upper level trough has and will
continue to decrease the instablilty over the area. Enough to
keep thunderstorms out of the forecast. The clouds and rain
will also not allow for much daytime heating with highs a couple
of degrees either side of 60.
Upper level trough east of the area tonight with showers
becoming isolated overnight. Convergence zone over Snohomish
county in the evening will move into the Cascades before
midnight. Lows in the mid 40s to lower 50s.
Thursday morning looks dry with the trough well to the east and
the next approaching system still offshore. Front approaching
the coast and weakening by the end of the afternoon. Rain
chances spreading inland in the afternoon. Westerly flow aloft
will rain shadow the Central Puget Sound. Another cool day with
highs in the mid 50s to lower 60s.
Front falling apart as it moves through Western Washington
Thursday night. Rain along the coast and over the Northwest
Interior with just a chance for rain elsewhere. Not much in the
way of cold air behind the front early Friday morning leading to
just a chance of post frontal showers in the lowlands and
showers likely in the Cascades. Lows in the 40s.
Fast moving upper level trough moving into Western Washington
Friday for another round of showers. Trough becoming negatively
tilted Friday afternoon as it moves inland. Instablilty indexes
not too impressive but enough to have a slight chance of
thunderstorms in the afternoon for most of the area. Friday
looks to be the coolest day in the next week with highs only in
the mid 50s, normal for the latter part of March. Felton
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Upper level trough remaining over Western Washington Friday
night into Saturday keeping at least a chance of showers in the
forecast. Could see a convergence zone move through the Puget
Sound area late Saturday afternoon into Saturday evening as the
trough drifts east.
Upper level ridge building offshore extending into Southern
British Columbia Sunday with the ridge remaining in place
through Tuesday. A weak system will try and move over the top of
the ridge into Western Washington Monday or Monday night.
Slow warming trend with highs in the mid 50s to lower 60s
Saturday, upper 50s to mid 60s Sunday and in the 60s Monday and
Tuesday.
&&
.AVIATION...
Southerly flow aloft early this morning as an upper level trough
begins to pass through the area. Wind speeds are expected to
pick up again to around 10-15 kts later this morning with gusts
up to 20 kts for the remainder of the morning and gusts
increasing to up to 25 kts after 18Z. These increased winds are
expected to remain in place throughout the afternoon and evening
before easing slightly back down into the 8-12 kt range by
midnight tonight.
Widespread VFR conditions in place with some localized MVFR
conditions in lower prone areas. While cigs are expected to
lower area- wide as the aforementioned trough moves through,
rainfall will be more widespread late this morning and this
afternoon, majority of sites should still drop down into MVFR
during this time frame. On the back side of this feature,
however, recovery should be quick with VFR conditions returning
this evening. This may only be short-lived, especially for those
terminals more prone to lower cigs, as low-level moisture
should nurture the re- emergence of MVFR cigs by late tonight
and into Thursday morning. The development of a PSCZ this
evening may hasten this lowering at PAE, as well as keep showers
going longer than surrounding terminals.
KSEA...VFR conditions, with southwesterly winds persisting between 7-
12 kt. Gusts to 20-25 kt expected to emerge early this afternoon as
wind speeds increase to 10-15 kt by 20Z. Ceilings will lower to MVFR
later this morning as general shower activity increases. Showers
will decrease this evening, although a PSCZ looks to develop and
linger into tonight. This feature looks to largely stay to the north
of the terminal at this time.
18/Mazurkiewicz
&&
.MARINE...
Persistent onshore flow will allow for increased speeds in the
Strait this morning, and will initially start off at Small
Craft Advisory strength, before increasing to Gale Force
Strength. Latest guidance suggests a 60-70% chance of gusts up
to 35 to 40 kts, and with more frequently of these stronger
gusts, have issued a Gale Warning for the Central and Eastern
Strait starting this afternoon. At the tail end of this
headline, looks like there might be some spillover into the
Northern Inland Waters, and as such they will be included in
a Small Craft Advisory later this afternoon to its conclusion
tonight.
Otherwise, seas building over the coastal waters with a
mix of a longer period and shorter period wave groups will
bring confused seas that may be more hazardous than the wave
heights (5-7 ft) would otherwise suggest. Latest model runs,
while still supporting this prospect, still do not lend much in
the way of confidence or of a widespread occurrence. As such,
will keep coastal waters without headline with the morning
forecast issuance. Otherwise, onshore flow continues through the
Strait of Juan de Fuca later this week with northerly winds
over the coastal waters. Another round of building seas to 8-9
ft over the coastal waters around Saturday from a distant
disturbance.
18/Mazurkiewicz
&&
.HYDROLOGY...
The daily hydrology discussion has ended until the
start of the next rainy season; it will only be updated during
this time as needed.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 1 PM PDT this afternoon for Central
U.S. Waters Strait Of Juan De Fuca-East Entrance U.S.
Waters Strait Of Juan De Fuca.
Gale Warning 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 until 11 PM PDT this evening for Northern
Inland Waters Including The San Juan Islands.
&&
$$
NWS SEW Office Area Forecast Discussion