376
FXUS66 KSEW 270322
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
820 PM PDT Thu Jun 26 2025

.UPDATE...Showers remain present on radar this evening with the
highest concentration of activity focused over the northern third of
the area, north of Jefferson and King counties. For points south,
activity is more isolated. Showers are on track to gradually ease
overnight, becoming more scattered. Inherited forecast remains on
track. No need for evening updates.

&&

.SYNOPSIS...A passing frontal system will bring light showers across
western Washington through Friday. High pressure will build over the
region this weekend into early next week, bringing a sharp rise in
daytime high temperatures, peaking on Monday. This ridge will begin
to weaken some going into the new week with temperatures cooling
slightly and a few more clouds.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...Pretty cloudy this
afternoon across all of western WA (seen on satellite). The next
shortwave trough is on its way inland (just offshore as of writing).
It is driving a surface low pressure system that is expected to
bring an occluding front through the region later today into Friday.

The radar has a couple areas of showers moving through the region.
A quick "waiver" pre-event round of showers is moving through the
north Cascades and parts of Whatcom/Skagit Counties. A more
widespread line of rain showers is approaching the coastline this
afternoon. It is expected to move across all of western WA during
the late afternoon and evening hours. Cloud coverage is going to
remain relatively intact Friday morning as another round of showers
moves through in the afternoon and evening. Most of the showers will
wrap up by Saturday morning. Precipitation amounts will be
relatively light across the region, with totals being several
hundredths of an inch of rain (couple areas in the north Cascades
may get a couple tenths of an inch). Highs today and Friday will
remain cool (50s and 60s), with a few 70s by Saturday in and south
of Puget Sound.

The rest of the weekend will be dry as an upper level ridge builds
over the Pacific Northwest (and as high pressure builds offshore).
The skies will begin to clear out Saturday evening across the
region, with Sunday being relatively clear. Some of the temperatures
will climb into the low 80s (particularly in South Puget Sound and
in some Cascade Valley areas). Remaining areas will see highs in the
60s and 70s. HeatRisk will remain minor (yellow) on Sunday. Winds
will remain light through the period, but there could be some breezy
north winds through Puget Sound Sunday afternoon (up to 20 mph).

.LONG TERM /MONDAY THROUGH THURSDAY/...High pressure will continue
into Monday, with Monday expected to be the warmest day of the week
with clear skies. The warmer spots South Puget Sound and Cascade
Valley areas) may see highs approach upper 80s to low 90s.
This will uptick the HeatRisk into moderate (orange) in these areas.
After Monday, the ridge is expected to break down and move east,
giving way to a more zonal/dry flow pattern across the region.
Temperatures will cool down slightly into the upper 70s/low 80s for
highs through the week. There does not appear to be any chance of
moisture next week (although a couple ensembles hint at a possible
trough just after the 4th of July).

HPR

&&

.AVIATION...Flow aloft remaining mostly westerly, although some
slight shifts to northwesterly may be possible at times. Surface
winds largely south to southwesterly, although CLM and HQM are more
westerly. Speeds generally less than 5 kts although some terminals
may exceed this with speeds occasionally ranging more 3-7 kts.

Abundant cloud cover as a weak system continues to push
across Western Washington with rain showers lingering, although
becoming more scattered overnight. Cigs reflective of location and
presence of showers, with the coast and terminals north of SEA/BFI
seeing mostly MVFR to IFR conditions. Remaining terminals are VFR.
Combination of low-level moisture and lingering system overhead
should result in widespread MVFR conditions or lower emerging
overnight and remaining that way into the morning. Afternoon mixing
should help cigs recover to low end VFR, save for terminals more
prone to lower cigs /HQM, PWT, CLM/, where recoveries may only peak
at MVFR.

KSEA...VFR conditions with majority of showers now to the north of
the terminal. Ceilings will decrease early Friday morning into MVFR
(around 7z-8z), with the chance of another round of light scattered
showers possible Friday morning. Guidance hints at some improvement
as early as 20z-21z into low-end VFR. Southwesterly winds at 5-8 kt
through the TAF period.

29/18

&&

.MARINE...High pressure will build over the waters late Friday and
will persist into the weekend, which will lead to northwesterly flow
over the coastal waters. High pressure will weaken slightly on
Monday, but will be the dominant feature for next week, keeping
northwesterly surface flow over the coastal waters. Marine
conditions look to remain benign through next week. Westerly pushes
will occur each evening across the Strait of Juan de Fuca, but at
this time there is not strong signal that sustained wind speeds and
gusts will meet small craft thresholds. Seas will be 3-4 ft through
Friday and will increase slightly during the weekend to 4-6 ft,
persisting into early next week.

29

&&

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

$$