FXUS66 KSEW 122303
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
303 PM PST Fri Dec 12 2025

.SYNOPSIS...Elevated river runoff conditions will continue with
significant river flooding impacts for many areas. Saturday
will see much needed drier weather ahead of a weak frontal
system Saturday night into Sunday. A stronger system will follow
Monday into Tuesday with heavier precipitation and potentially
windy conditions for some areas. There is potential for heavy
mountain snow Tuesday and Wednesday.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...High pressure is
giving us a brief respite from the wet and active weather this
week. That being said, there are still numerous rivers within
flood stage with associated impacts. While some rivers have
crested and are receding, we are still seeing new floods based
on dam releases.

Rain chances increase again moving into Sunday as the ridge
flattens. Snow levels remain high, over 6,000 ft, with lowland
totals generally under 0.10" and 0.25" or less in the mountains.
These totals are not hydrologically significant, though.
However, precip coverage and rates will be increasing moving
into Sunday night and Monday. 33

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...The next AR event, slated
for Sunday night and Monday, brings another round of heavier
precipitation to western Washington. Interior lowland areas may
see an additional 0.50-1.00" of rain, with 1-2" over the coast
and 1-3" (with locally higher amounts) in the mountains. These
totals may prolong river flooding and/or renew flooding for a
few rivers across the region. However, we are not anticipating
widespread major flooding as we've just seen. It'll be windy as
well with widespread south wind gusts to 30-40 mph. We stay in a
moist/wet pattern moving into Tuesday and Wednesday, but by
then the snow levels will be lowering to around 4000 ft (Tue)
and 2500 ft (Wed) with the focus turning toward heavy snow in
the Cascades and passes. Total snow amounts in the mountains
remain high moving toward the end of the week as snow levels
remain low. 33

&&

.AVIATION...Ceilings have been slow to improve this afternoon
from IFR/LIFR, but the latest guidance still suggests
improvement into MVFR is possible this evening, with some
guidance suggesting some terminals may see low-end VFR at times.
Improvement will be brief as IFR and LIFR conditions are
expected to return to the majority of terminals overnight.
Similar to today, visibilities may be limited to as low as
1/4SM. Improvement into VFR expected in the afternoon after 20Z
for the majority of terminals.

KSEA...Ceilings are slowly improving this afternoon and brief
improvement to MVFR possible after 00Z. Conditions will deteriorate
overnight as IFR and LIFR ceilings are expected to return. Limited
visibility is also expected at the terminal. Latest guidance
suggests a 20-25% chance of seeing visibility below 1SM between 12Z-
18Z. Improvement into VFR expected after 19Z-20Z. Southwesterly
winds will become southeasterly overnight after 12Z at 3-5 kt.

29

&&

.MARINE...A series of weather systems are expected to move
through area waters starting this weekend and continuing into
next week. A weak system is expected to move over area waters on
Saturday into Sunday morning. There is high confidence (70-90%)
that this system will bring gusts meeting small craft advisory
thresholds for the coastal waters as the front pushes through.
The next system arrives Sunday night continuing into Monday.
This system will be much stronger and bring elevated seas and
winds. Latest guidance suggest there is high confidence
(70-100%) for winds meeting small craft thresholds. There is
also moderate confidence (50-70%) for gale gusts over the
coastal waters. Seas will build to 13-19 ft for the coastal
waters. Seas will decrease slightly Tuesday morning, but still
hover between 10- 13 ft. Another system on Tuesday will bring
impactful weather to area waters. Latest guidance suggests
another round of small craft winds (50-90%) chance, with highest
probabilities over the coastal waters and western Strait. Seas
will build again to 14-17 ft.

29

&&

.HYDROLOGY...Key messages below.

* Numerous River Flood Warnings remain in effect across western
  Washington, with varying times and flood levels.

* A Flash Flood Watch remains in effect for a potential levee
  failure of the Skagit River below Sedro-Wooley to the mouth of
  the Skagit River through late Friday.

* More wet weather early next week with potential for renewed
  flooding.

With very wet antecedent soil conditions, the landslide threat
across the region has increased with this system, and several
landslides and mudslides have already occurred in steep terrain
across western Washington. Potential has also increased for
debris flows over area burn scars, which continue to be
monitored.

While the threat of urban flooding has decreased, the threat of
small stream flooding, as well as for areas with poor drainage,
continues to pose a risk of localized nuisance flooding and
ponding on roadways. Low water crossings may become impacted or
impassable.

The latest river observations and forecasts can be found at
water.noaa.gov.

33

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Flash Flood Watch through Saturday morning for Lowlands of
     Western Skagit and Northwestern Snohomish Counties.

PZ...Small Craft Advisory from 4 PM Saturday to 1 PM PST Sunday for
     Coastal Waters From Cape Flattery To James Island 10 To
     60 Nm-Coastal Waters From Cape Flattery To James Island
     Out 10 Nm-Coastal Waters From James Island To Point
     Grenville 10 To 60 Nm-Coastal Waters From James Island To
     Point Grenville Out 10 Nm-Coastal Waters From Point
     Grenville To Cape Shoalwater 10 To 60 Nm-Coastal Waters
     From Point Grenville To Cape Shoalwater Out 10 Nm.

&&

$$