811
FXUS66 KSEW 170317
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
817 PM PDT Mon Jun 16 2025
.SYNOPSIS...A series of weak systems are expected to brush the
area Tuesday and Wednesday bringing increased cloudiness and a
chance of showers to western Washington. More widespread
precipitation and cooler temperatures look to be on track Friday
into the weekend as the upper low moves onshore over the
region.
&&
.UPDATE...Other than minor tweaks to the aviation discussion
below, no major updates for the forecast this evening.
HPR
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...The upper level
trough over the eastern Pacific will continue to influence the
region through the first half of the week allowing a series of
weak systems to brush the area. The first will approach the
region on Tuesday, boosting clouds and bringing a chance of
light precip/showers mainly to the coast during the day then
inland Tuesday night into Wednesday. There is a chance of up to
a quarter of an inch of rain is possible particularly over the
Olympic Peninsula and across the North Cascades. High
temperatures Wednesday will be run a few degrees cooler, with
most spots likely only climbing into the 60s, though a few may
make it into the low 70s.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...Thursday continues to
look like a transitional day - mostly dry with a few lingering post-
frontal showers. The upper level low expected to being to shift
onshore Friday into Saturday will bring more widespread rain and
cooler temperatures. Rainfall amounts across the lowlands at
this time continue to look around a tenth of an inch to a
quarter of an inch. Of note snow levels are expected to dip
down to 5000-6000 ft over the weekend, bringing the potential
for light snow accumulations to the tallest mountain peaks.
High temperatures over the weekend will generally trend below
normal as a result, with highs only expected to be in the 60s. Those
with plans for outdoor recreation in the mountains will want to
monitor the forecast for the latest information.
&&
.AVIATION...Southwest flow aloft continues into Tuesday as troughing
approaches Western Washington offshore. VFR conditions this evening
with high clouds at times. Onshore flow will increase at the surface
tonight into Tuesday morning. Stratus will spread inland during this
period, resulting in MVFR/IFR cigs for majority of the coast, with
localized LIFR cigs. The eastward extent of stratus is expected to
be generally from KPWT to KTIW, but will have to monitor any stratus
potential for other TAF sites as well from SEA to PAE Tuesday AM
(mainly 12 to 17z). VFR conditions otherwise for interior areas on
Tuesday, with continued stratus along the coast into Tuesday
afternoon. West winds will become lighter tonight before increasing
from the S/SW on Tuesday.
KSEA...VFR conditions this evening with high clouds at times.
Stratus will push inland tonight into Tuesday morning. At this time,
low stratus is expected to remain SW of the terminal. But will have
to monitor any further eastward progress towards the terminal,
mainly between 13 to 17z. VFR conditions otherwise on Tuesday. NW
surface winds for a brief period through 05-06z this evening before
transitioning back to S/SW tonight. JD
&&
.MARINE...High pressure at the surface will weaken tonight into
Tuesday. A weak front is expected to bring showers across the waters
Tuesday evening into Wednesday. Expect high pressure to rebuild
Wednesday night into Thursday, before a more organized system pushes
through the region Friday into next weekend.
The small craft advisory for the Strait of Juan de Fuca continues
for this evening/tonight for west winds of 15 to 25 kt. Another push
will be possible again Wednesday through Friday.
Seas increasing to 3-6 feet tonight through Saturday, with possible
increases to 6-8 feet next weekend with the weather.
HPR
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 2 AM 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
Discussion Script by Ken True at Saratoga Weather - WFO Script by SE Lincoln Weather
