245
FXUS66 KSEW 272131
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
231 PM PDT Thu Mar 27 2025

.SYNOPSIS...A deep upper level low remains offshore, generating
showers and cooler conditions across western Washington. Another
system will arrive over the weekend, but the troughing pattern
remains over the eastern Pacific into next week.


&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...A wide area of rain
showers is moving up from the south, impacting Puget Sound and the
Coast. There is a very limited threat for a lightning strike or
two, but primarily, rain and breezy winds will be the primary
threats. Conditions are going to be windy along the coast and
north interior.

A deep low is positioned offshore, and will spin into British
Columbia over the weekend. That said, there is broad troughing
that will spin shortwave systems into the area for more showers
tomorrow and Saturday. With continued rain over the Olympic
Basins, the Skokomish river is expected to reach minor flood
stage on Saturday, but it looks to be a short lived flood as the
rain tapers off late Saturday into Sunday. Snow levels decrease
below 3000ft across the Cascades by Saturday morning, but with
most of the QPF along the Olympic Peninsula, this will translate
to very light snow accumulations over the Cascade passes.
Temperatures on Saturday will be in the mid 50s, with slight
warming into Sunday where temperatures could reach the low 60s.

.LONG TERM /MONDAY THROUGH THURSDAY/...After shortlived ridging
on Sunday, another low pressure system approaches the coast and
begins introducing more precipitation into the region on Monday.
The cool and showery conditions linger through Tuesday. Another
potentially more organized system may approach from the south but
at this point, it looks like much of its strength will dissipate
before reaching western Washington. For now, another round of rain
and isolated breezy conditions are possibly resuming late in the
week. Ultimately, it doesn`t appear that appreciable ridging takes
shape until the day 8 or day 9 timeframe.

21

&&

.AVIATION...An upper level low will swing a surface low
pressure/trough centered off the coast of WA northward on Friday.
The southwest flow aloft will decrease as the low tracks northward.
Widespread rain showers will move northward through the afternoon
and evening across all terminals. The threat of thunder remains very
low for the afternoon (at or less than 10%) - too low to include in
the TAFs, but cannot rule out a clap of thunder if a strong shower
develops. Ceilings will remain VFR as the showers move through the
region, but can`t rule out a drop of visibilities down to 4 SM if a
shower become heavy. Breezy south winds at around 10 kt with gusts
to 20-25 kt will accompany the showers, especially Thursday evening
through Saturday morning. Lower ceiling drops to MVFR are expected
Friday morning through Friday afternoon. The showers will become
more scattered during the day Friday.

KSEA...Widespread rain showers over the terminal through tonight,
becoming more scattered on Friday. VFR ceilings will drop to MVFR
between roughly 12Z-18Z Friday (improving to VFR after). Gusty winds
out of the south at 6-10 kt with gusts to 20 kt will become 10-15
gusting to 25 kt Friday.

HPR


&&

.MARINE...An upper level low with an associated surface trough/low
pressure centered off the coast will move north towards B.C. Friday.
Rain showers will continue over most of the waters this afternoon
through much of Friday into Saturday morning. Blustery south winds
will continue over most of the waters during this time as the system
moves north. Gales in the coastal waters will diminish down to 20 to
30 kt from the south through Saturday. These winds will be
accompanied by building seas of 14 to 18 feet through Friday,
decreasing to 6 to 8 feet Saturday through next week. Small craft
advisories will replace the gale warning for the coastal zones
tonight through Saturday morning (with the West Strait of Juan de
Fuca included). The small craft advisory for the Grays Harbor Bar
will continue through Friday afternoon. Winds will also pick in
Puget Sound/Admiralty Inlet/East Strait of Juan de Fuca/Northern
Inland Waters Friday as the system moves north. Small craft
advisories were issued for these zones, with a low chance of a
possible gale gust in the East Strait of Juan de Fuca.

Going through the weekend, the pattern will briefly dry out late
Saturday into early Sunday. Additional systems are expected to pass
over the waters next week. There is no hazard concern with these
systems at this time.

HPR


&&

.HYDROLOGY...With on and off precipitation expected through
Saturday and a break on Sunday, most area rivers are not expected
to respond drastically. Even the forecast for the Skokomish river
has come down to a brief period of minor flood stage on Saturday.
Conditions will be monitored over the basin but for now the flood
watch will remain in effect.


&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Flood Watch from 5 PM PDT this afternoon through Saturday
     afternoon for Foothills of the Western and Southern Olympic
     Peninsula-Middle Chehalis River Valley-Olympia and Southern
     Puget Sound-Olympics-Southern Hood Canal-Willapa and Black
     Hills.

PZ...Small Craft Advisory until 8 AM PDT Friday for Grays Harbor Bar.

     Small Craft Advisory from 2 AM Friday to 5 AM PDT Saturday 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-West Entrance U.S.
     Waters Strait Of Juan De Fuca.

     Small Craft Advisory until 5 PM PDT Friday for East Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 11 PM this evening to 5 PM PDT Friday
     for Admiralty Inlet-Northern Inland Waters Including The
     San Juan Islands-Puget Sound and Hood Canal.

     Gale Warning until 2 AM PDT Friday 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.

&&

$$