147
FXUS66 KSEW 060232
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
733 PM PDT Thu Jun 5 2025

.UPDATE...Current satellite shows stratus still clinging to the
coastline while the remainder of western Washington remains
generally clear with a few high clouds. There does appear to be a
more solid bank of mid-to-upper level clouds further upstream off
the southern tip of Vancouver Island and would expect those to roll
in overnight. Inherited forecast covers the situation well. No need
for an evening update.

&&

.SYNOPSIS...High pressure will remain centered offshore through
early this weekend. As it slides inland Saturday and Sunday, an
upper level ridge will build over the entire region over a
surface thermal trough up the coastline. This will likely lead to
warm temperatures on Sunday with highs approaching near record
levels in the upper 80s to low 90s. The ridge will move out of the
region Monday, and temperatures will gradually cool off through
next week with the outlook remaining dry.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...Western Washington sits
synoptically in between a trough feature to the east over the
Rockies (positively tilted), and a large scale high that continues
to remain centered over the Pacific. Except for maybe some wispy
cirrus high above, inland areas remains clear this afternoon with
temperatures already up into the 70s in urban and valley areas.
There remains some stratus off the coast with a counter-clockwise
spinning meso-low spinning offshore and a few clouds seeping
through the Strait of Juan de Fuca. Clouds will begin to fill in
inland areas tonight into Friday (with the continuation of
onshore/northwest flow). Friday will be similar to Thursday, dry
and few degrees warmer with high temperatures approaching 80 in
the south Puget Sound/Interior and adjacent valley areas. Morning
temperatures Friday and Saturday morning remain cool with lows
around 50.

Saturday/Sunday: The high pressure centered offshore will finally
begin to move inland (models agree on having it move across
northern Oregon Saturday night/Sunday). An upper level trough
will also dig over southern Canada Sunday with a ridge building
over northern Washington/British Columbia. MSLP also clearly shows
a thermal trough moving up the coast below the high
pressure/ridge.

Saturday will see highs range from the upper 70s to low 80s for
most places away from water/higher elevations. The winds will be
light out of the northwest only around 5 mph for most places (not
too much of a breeze). Low temperatures will only drop into the
upper 50s for most places going into Sunday. The HeatRisk on
Saturday is generally minor (1/4) for all areas except for a
pocket of moderate in the South Interior (2/4). High temperatures
will peak Sunday, with temperatures expected to max out in the
80s (and a few areas in southern Puget Sound/South Interior
peaking in the upper 80s to low 90s). This will result in more
widespread moderate (2/4) HeatRisk across most urban and valley
areas inland. Additionally, lows may only drop down to 60 for many
areas. Given the early onset of heat for this time of year, a
heat advisory headline may be needed for Sunday as many people
venture outdoors over the weekend.

Lastly, for persons spending time near the waters over the
weekend, many of the waters remain very cold with Lake Washington
hovering around 65 degrees, Puget Sound at 52 degrees, the Pacific
Coast between 50-55 degrees), Lake Sammamish at 68 degrees, and
most area rivers ranging from 48-60 degrees. If you plan to spend
time in or near the water, wear a life vest and keep a close eye
on persons in your party (including children). Cold shock can set
in from water temperatures of 50-60 degrees (even for experienced
swimmers).

.LONG TERM /MONDAY THROUGH THURSDAY/...The aforementioned high
will continue to move inland and progress east through the
Rockies. The flow will become a bit more zonal which will allow
temperatures to decrease throughout the week. Monday will see a
continuation of highs in the upper 70s to mid 80s. Tuesday will
see more of a drop into the low and upper 70s, with
Wednesday/Thursday seeing a further drop into the upper 60s to low
70s. A couple of ensembles show a trough moving through next
Thursday. The only chance of precipitation with this will be a few
showers in the Cascades at this time, which is not expected to
produce any significant rainfall at this time.

HPR

&&

.AVIATION...VFR conditions across Western Washington terminals with
mostly clear skies. Mid-to-high level clouds to increase tonight.
Guidance seems to be divided on the low stratus making a comeback in
the morning. Models that do show the low stratus hint at a 20-40%
chance of MVFR ceilings; however confidence is high that the low
stratus will impact coastal terminals, bringing ceilings down to
IFR/LIFR. If ceilings do lower for interior terminals, conditions
expected to improve to VFR late Friday morning. Northerly surface
flow expected to persist with winds at 7- 10 kt, subsiding to 2-5 kt
overnight.

KSEA...VFR conditions expected for the majority of the TAF period.
Mid-to-high level clouds will increase tonight. Models are
struggling with the return of the stratus for Friday morning, with a
20-25% chance of MVFR ceilings between 14z-17z. At this time, not
feeling confident enough to lower ceilings down to MVFR for this TAF
package. NW surface winds 8-10 kt this afternoon/evening will turn
more NE overnight, decreasing to 3-5 kt.

33/29

&&

.MARINE...Surface high pressure offshore will be the dominating
feature into next week. It will move over the inland waters on
Sunday and east of the area on Monday.

A small craft advisory is in effect for the outer coastal waters for
choppy seas of 7-10 ft with a period of 8-10 second through at least
Friday. May have to extend the advisory into Saturday morning as
seas look to remain choppy. In addition, diurnal westerly pushes
across the Strait of Juan de Fuca expected today and tomorrow,
bringing low-end small craft winds to the Central Strait. May see
some occasional gusts reach into the small craft criteria for the
eastern portion of the Strait (did not feel confident enough to add
the East Strait to the SCA as sustained winds looks to remain below
criteria and gusts are on the marginal side for a brief period).

29

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 6 PM this evening to 2 AM PDT Saturday
     for Central U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 6 PM this evening to 6 AM PDT Saturday
     for Coastal Waters From Cape Flattery To James Island 10 To
     60 Nm-Coastal Waters From James Island To Point Grenville
     10 To 60 Nm-Coastal Waters From Point Grenville To Cape
     Shoalwater 10 To 60 Nm.

&&

$$