599
FXUS66 KSEW 140301
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
800 PM PDT Fri Jun 13 2025

.UPDATE...Much of western Washington socked in with clouds this
evening with the exception of along the immediate coast. Continued
onshore flow and resultant push tonight will likely fill in what few
gaps there are with clearing expected by Saturday afternoon.
Inherited forecast on track with no need for evening updates.

&&

.SYNOPSIS...An upper level low will remain off the British
Columbia coast for much of the forecast period. Dry conditions and
seasonable temperatures this weekend with diminishing cloud cover. A
series of weak fronts will bring the chance for rain back to the
area Monday, with best chances on Tuesday. Dry conditions will
resume Wednesday and into late next week.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY/...Upper level analysis shows
an upper level low just off the coast of northwest B.C.. The flow
aloft is southwest as a couple of weak troughs swing around the
low today/early Saturday. No significant weather is expected with
these troughs (other than there will remain a few more clouds
today with clearing expected to be minimal over most of western
WA,except for along and north of the Strait of Juan de Fuca). As
such, highs will remain cool with some areas remaining in the 50s
(some urban areas and areas clear will have the best chance of
seeing temps creep up into the 60s). Conditions will be dry
regionwide (though could be a few sprinkles in the Cascades this
afternoon).

Over the weekend: Down at the surface, high pressure will build
offshore with lower heights further inland to the east. This will
keep the flow onshore with light west to northwest winds at the
surface. There will be a descent push of marine air
tonight/Saturday morning (which will push most clouds back in
across the region). Once the weak trough passes through, clouds
will clear out going into Saturday afternoon and it will remain
dry through the weekend. Sunday will be sunnier compared to
Saturday with not as significant of a marine push Sunday morning.
Highs will be a touch warmer Saturday/Sunday with the clearer
skies - will peak Sunday with temps reaching upper 60s to mid 70s
(warmest temperatures from metro Seattle south along the I-5
corridor). Lows will remain comfortable with a few more low 50s
Sunday night (otherwise lots of 40s and potentially a few South
Interior locations getting close to dropping in the 30s Sunday
morning).

By Monday, another shortwave trough and weak front will approach
from the west, and begin to increase the chance of showers Monday
afternoon/evening along the coast. Amounts are expected to be
light. Cloud coverage will remain partly cloudy/sunny through
Monday with clouds increasing along the coast. Temperatures are
expected to remain steady from Sunday.

.LONG TERM /TUESDAY THROUGH FRIDAY/...The low offshore will remain
in place through much of next week. It does not appear (based on
ensembles) that it will move inland until Friday of next week. The
front/trough approaching Monday will continue into Tuesday with
shower chances increasing across the region Tuesday into
Wednesday. Amounts at this time will be light (hit or miss showers
expected). There is also a 10-15% chance of thunder in the north
(Whatcom County), however at this point, the best chance of
thunder is over the border into Canada (but this may shift
as more guidance comes in). Another round of showers is possible
Friday as the low is expected to move inland by then. Highs again
will remain steady and right around normal through the week.

HPR

&&

.AVIATION...An upper level low off the BC coast will keep flow aloft
generally west to southwesterly. Surface winds generally south to
southwesterly with speeds 5-10 kts. Exceptions are HQM and CLM,
where the direction is more westerly and PAE, which is seeing
occasional shifts to northerly. Most terminals will shift to
northerly late Saturday morning or early Saturday afternoon.

Cigs remain VFR at the time of this writing, however in keeping with
current pattern should see conditions lower to MVFR very late
tonight/very early Saturday morning. Late morning should see cigs
lift with VFR returning and only high clouds remaining by mid
afternoon.

KSEA...VFR conditions in place with cigs generally 4000-5000 ft.
Will see these gradually lower tonight with MVFR conditions expected
by 12Z thanks to another westerly push. Cigs expected to lift by
20Z, returning to VFR conditions. Southwesterly winds overnight into
Saturday morning with speeds 4-8 kts. Winds shift northerly in the
afternoon and pick up a little more speed, ranging 5-10 kts.

18

&&

.MARINE...Surface high pressure will move to the east this weekend
and over the coastal waters. Diurnal westerly pushes will occur
every evening in the Strait of Juan de Fuca (some likely needing the
issuance of headlines). This evening`s push looks to remain below 21
kt and have decided to hold off on issuing a Small Craft Advisory.
However, may occasionally see gusts in the 21-25 kt range.
Tomorrow`s push down the Strait will be stronger and will likely
need additional headlines as sustained winds will be around 21-25
kt. A weakening front will move over the coastal waters on Monday,
followed by additional systems next week. Seas will remain below 10
ft into the weekend and next week.

29/18

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.

&&

$$