560
FXUS66 KSEW 241844
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
1044 AM PST Mon Nov 24 2025

.SYNOPSIS...
Isolated morning showers will herald a dissipating
front moving through western Washington by this afternoon, keeping
precipitation in the forecast today. A warm front will move onshore
on Tuesday, lifting northwards Wednesday. Unsettled weather
continues for the holiday and the rest of the week as more systems
move through the Pacific Northwest bringing more precipitation and
cooler conditions.

&&

.SHORT TERM /TODAY THROUGH WEDNESDAY/...
Current radar
continues to show some lingering convergence zone activity over
portions of King and Snohomish counties...but also seeing some
isolated showers over the nearshore coastal waters. These are likely
a preamble to additional rain with the incoming weakening
front...echoes of which are just barely entering radar range at the
time of this writing. Otherwise, latest satellite imagery shows a
gap over the western half of the CWA, where clouds are minimal. This
has had the unfortunate side-effect of allowing some patchy fog to
develop at some obs sites, but not a widespread concern.

Models remain consistent with incoming feature approaching W WA as a
weak impulse with little more than light precip expected with it. An
extremely transient ridge follows for largely dry conditions
overnight followed by a far more convincing system Tuesday with
widespread rainfall expected by the afternoon. The warm nature of
the front will allow snow levels to rise, so while snowfall in the
mountains will still occur, amounts look to fall short of any
headline amounts. The only zone that could prove to be an exception
will be in the central Cascades, including Stevens Pass, where
amounts could land right around 6 inches by Wednesday morning. Will
pass on any winter headlines there at this time, given that the
aforementioned rising snow levels could be a counterpoint to these
precip amounts, potentially making the current forecast an
overestimation, even if it is a slight one. Given the potential for
holiday travel, will still advise day crew to interrogate further.

Models suggest at least some degree of a break Wednesday morning,
however how long that lasts, if it exists at all, is a point of
contention. Deterministic GFS does bring in a discernible ridge,
keeping conditions dry for not only Saturday morning, but even into
late Wednesday afternoon/early Wednesday evening. The deterministic
ECMWF shows a ridge also...but with it a slug of lingering moisture,
which would keep high-end Chance to Likely PoPs over the entire area
/50-80 pct/. Ensemble guidance seems to be leaning drier while NBM
shows more favor to the wetter Euro solution. While NBM solution is
in the forecast, it is worth placing a large asterisk over this
portion of the forecast, as uncertainty and resultant lower
confidence should be kept in mind.

A cooling trend will kick-off today, with temps a degree or two
cooler than yesterday in general: most locations seeing highs in the
upper 40s to around 50. More significant cooling for Tuesday as
highs slip into the lower to mid 40s. Thanks to the aforementioned
warm front slated for Tuesday, W WA feels the impact from that
feature in the highs on Wednesday, as daytime temps return to the
upper 40s to lower 50s.

18

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Model unity resumes
Wednesday night with the next round of precip entering the area,
although there is a wide array of solutions when it comes to how much
precip W WA will see. Adding additional complications is the
continued disagreement where the track of the upper level low will
go and as such whether or not precip persists throughout the
Thanksgiving holiday. Deterministic GFS wants to lift this track to
the north which may keep the first half of Turkey Day dry while
deterministic ECMWF brings the upper low pretty much right through W
WA, making the entire day a wash. Ensembles here really split the
difference: consistent chances for precip but easing amounts
throughout the day. This uncertainty persists for the remainder of
the forecast period. GFS brings in a secondary system for Friday,
keeping precip in the forecast for the rest of the weekend as it
sits and churns over the Pac NW. The ECMWF, however, actually wants
to bring is a sizable ridge that would hold court throughout the
weekend. While ensembles show a slight favoring of the drier
solution...not entirely removing precip but at least keeping amounts
pretty light...the wide gulf in the differing solutions casts the
entirety of the long term in a high degree of doubt at this time.
Daytime high temp forecasts reflect this, keeping temps static in
the mid 40s to around 50 throughout the period.

18

&&

.AVIATION...
Majority of terminals VFR this morning. Latest radar imagery shows a
fast frontal system approaching the interior terminals. Expecting it
to impact the interior terminals between 18Z-21Z. The low level air
mass remains moist with onshore flow and expect pockets of MVFR
ceilings with showers. Widespread rain Tuesday with a stronger
Pacific system. 33/29

KSEA...Main band of showers associated with a frontal system will
pass through the terminal beginning around 19Z, with rain activity
tapering off after 22Z. S winds around 6-10 kt becoming SE Monday
night. 33/29

&&

.MARINE...
A weak frontal system will shift inland today with
onshore flow. Seas over the Coastal Waters will subside under 10 ft
this morning. South winds will increase on Tuesday as a stronger
Pacific frontal system moves in. Low pressure will weaken as it
shifts inland on Wednesday. Expect elevated winds and seas on
Thursday as another strong system reaches western WA. The flow will
turn more northerly and offshore late in the week with Fraser River
outflow winds possible. 33

&&

.HYDROLOGY...
Light precipitation at times is expected today with
minimal hydro concerns. A stronger weather system will move into
Western Washington late Tuesday, with continued precipitation at
times through Thursday. Rivers will rise as a result of the steadier
precipitation, especially for rivers off the central and southern
Cascades, as well as the Olympics. Snow levels will also rise to
5500 to 6500 feet by late Wednesday. At this time, the Skokomish
River in Mason County is the primary river being monitored for river
flooding by Thursday. However, latest QPF forecasts are lower than
previous cycles over this area. If this holds true, it would fall in
line with the majority of prior forecasts...with yesterday`s
forecast proving to be an upper outlier. Will need to monitor future
solutions to ensure this lower trend remains intact. If it does,
while there will be rises on the Skokomish, its crest should still
fall short of flood concerns. This, as well as other rivers, will
continue to be monitored.

18

&&

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

&&

$$