Washington State Forecast Discussion

Western Washington


563
FXUS66 KSEW 210929
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
129 AM PST Sat Dec 21 2024

.SYNOPSIS...Another front arrives today for additional
precipitation and breezy winds. A more active pattern is going to
evolve this weekend and last into next week, with an increased
chance of impactful weather arriving during and after the
holidays.


&&

.SHORT TERM /TODAY THROUGH MONDAY/...The next frontal system will
be arriving this morning, for elevated winds along the immediate
coast and east Puget Sound lowland locations. A wind advisory has
been added for the coast to account for stronger winds this
morning. Wind direction will begin as easterly this morning,
transitioning to southerly by early afternoon. Rain amounts won't
be particularly impressive with this system, with showers largely
becoming scattered by this afternoon. Snow levels will lower to
around 4000 feet tonight for a few inches of snow at Stevens and
White Pass. The next front arriving on Sunday has more in the way
of QPF and the region can expect more breezy southeasterly flow by
Sunday afternoon. Some of the high res models are suggestive of
some instability and possible convection in the area over the
weekend, but for now, the albeit slight chances will still be
confined to the coast.

With minimal reprieve, another system arrives on Monday. For the
lead time between now and Monday, the models are already confident
on widespread and gusty easterly winds. Speeds and timing could
change somewhat over the weekend, but it does increase confidence
in the event overall. The bulk of Monday's QPF seems to arrive in
the afternoon, leading to a rainy and windy evening and overnight
period.

.LONG TERM /TUESDAY THROUGH FRIDAY/...Rain and breezy winds will
linger into Tuesday, with yet more storms poised to arrive
thereafter. The main impacts possible at this stage will be
ongoing moderate to possibly heavy rain, breezy to windy
conditions, and lowering snow levels on and after Christmas day to
around 3000 feet causing impactful snow at all Cascade passes.

Kristell


&&

.AVIATION...Mainly VFR with areas of localized IFR/LIFR in fog early
this morning. Patchy fog along the Strait of Juan de Fuca, Kitsap
Peninsula, and Chehalis Valley lowering visibilities to a mile or
less through roughly 12z this morning. Offshore flow with breezy
E/SE winds will continue today as another warm front and trailing
cold front cross western Washington. Showers will spread northward
into the area after 12z Sat with most shower activity tapering
off by 6z Sun. Ceilings are favored to lower to low end VFR or
high end VFR as the showers move through.

KSEA...VFR with E/SE winds picking up this morning. Showers will
move over the terminal after 12z, with ceilings favored to lower to
near 3000 ft by the afternoon and continuing through the evening.
Surface winds generally 8 to 12 kt shifting more southerly by 18z
with gusts to 20kt throughout the afternoon and evening. Winds
easing to 4 to 8 kt and returning to E/SE after 6z Sun.

15


&&

.MARINE...A series of fronts will cross the region over the next
several days, maintaining seas above 10 feet and periods of breezy
conditions through the weekend and into early next week. A series of
fronts moving over area waters this morning will generate Gale force
winds and large waves across the outer waters today with Small Craft
winds through the northern Salish Sea through the Admiralty Inlet by
the afternoon. Winds will ease overnight, though seas will remain
elevated with an SCA to cover.

Another series of frontal systems will cross the region Sunday,
resulting in another slew of Gale and Small Craft headlines through
area waters. Additional headlines are likely heading into next week
as another round of windy conditions and elevated seas are expected
Monday, and potentially again on Wednesday.

Combined seas 10 to 14 feet will build upwards of 15 to 20 feet by
the afternoon today, where seas will remain elevated through Sunday
with long period swell. Seas will remain elevated above 12 feet
through the period, with another round of seas building to 18 to 22
feet on Monday and again towards the middle of the week.

15


&&

.HYDROLOGY...A series of disturbances over the weekend with
additional rounds of precipitation. Flooding is not likely but
minor rises on area rivers expected. The Skokomish River will
continue to recede slowly dropping just below flood stage
overnight then remain near flood stage through the weekend into
next week. Increasing precipitation around Christmas could push
the Skokomish back up to moderate flood stage. For the remaining
rivers, the threat of flooding will also increase in the middle
of next week as ensembles continue to indicate the potential for
significant precipitation. While discrepancies remain, this most
likely will lead to an increased chance of river flooding becoming
more widespread and landslide concerns that may impact holiday
travel.

McMillian/Felton


&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Wind Advisory from 4 AM early this morning to 2 PM PST this
afternoon for Central Coast-North Coast.

Wind Advisory until 7 AM PST this morning for East Puget Sound
Lowlands.

PZ...Small Craft Advisory from 6 AM this morning to 6 PM PST Sunday
for Grays Harbor Bar.

Small Craft Advisory until 4 PM PST this afternoon for West
Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory from 2 AM to 6 PM PST Sunday for Admiralty
Inlet-Northern Inland Waters Including The San Juan Islands-
West Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory from 8 AM this morning to 4 PM PST this
afternoon for Admiralty Inlet-East Entrance U.S. Waters
Strait Of Juan De Fuca-Northern Inland Waters Including The
San Juan Islands.

Gale Watch from late tonight through Sunday afternoon for East
Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory until 4 AM PST early this morning 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.

Small Craft Advisory from 4 PM this afternoon to 4 AM 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.

Gale Warning from 4 AM early this morning to 4 PM PST this
afternoon 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.

Gale Watch from late tonight through Sunday afternoon 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.

&&