Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
241
FXUS66 KSEW 130928
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
228 AM PDT Sun Oct 13 2024
.SYNOPSIS...An upper level ridge will produce one last dry and
mild day across Western Washington today before a series of
frontal systems bring rain, mountain snow, and progressively
cooler temperatures in the week ahead.
&&
.SHORT TERM /TODAY THROUGH TUESDAY/...An upper level ridge
shifting eastward will give Western Washington one final
completely dry day before a significant pattern shift brings a
series of fronts into the region in the week ahead. A layer of
stratus along the coast will make partial progress inland this
morning, but the remainder of the area will see a mostly sunny day
after any patchy fog dissipates. High clouds will start to creep
in by afternoon as the first of a series of frontal systems
approaches. The first front will be rather weak. Rain will reach
coastal areas by early Monday morning then spread inland toward
afternoon. Overall QPF will be on the light side with this system.
After a brief break Monday night into early Tuesday, a secondary
more potent system will arrive by Tuesday night with another round
of rain.
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...Wednesday will likely
be the pivotal day this week as a fairly strong front swings
onshore and the trailing upper trough arrives with snow levels
tumbling to some of the higher passes by late Wednesday night.
The upper trough remains overhead into Thursday for plenty of
shower activity and cooler temperatures.
There`s a noticeable difference between both deterministic runs
and the suite of ensembles toward the end of the week. And this
could have significant implications in terms of the weekend
forecast. The models have some degree of upper ridging returning
to the West Coast, but the strength and placement of the ridge is
important. There is a definitive split between the GFS and ECMWF
ensembles. A vast majority of the GFS ensembles depict an
atmospheric river funneling over the top of the ridge into mostly
southern British Columbia while the ECMWF/Canadian ensembles are
significantly more bullish with putting Western Washington in the
crosshairs of the moisture. Current forecasts have likely PoPs
for most of the area on Saturday, but if the ECMWF proves correct,
we`ll probably be looking at categorical PoPs everywhere with
considerable boosts to the QPF forecast. 27
&&
.AVIATION...Increasing southwesterly flow into Monday with upper
troughing over the NE Pacific and an approaching frontal system
tonight into Monday morning. A rather complicated pattern this
morning with stratus sliding inland along the Olympic Peninsula,
with clear skies and light south winds for the interior. Patchy fog
is expected to develop early this morning, particularly for the
southern Puget Sound, including KOLM and KPWT. Fog may also develop
elsewhere, towards KBLI, as well as KSEA and KBFI, but some
uncertainty exists given slightly elevated south winds as of 09z,
but winds are expected to become lighter this morning. In addition,
stratus will slowly slide eastward into the Southwest Interior, and
towards south Puget Sound, but advancement isn`t expected to far
into Puget Sound due to a lack of onshore flow. LIFR/IFR cigs
expected along the coast and Southwest Interior due to stratus, with
areas of LIFR vsbys elsewhere in areas of fog across the interior.
Otherwise, high clouds expected at times this afternoon, with
continued stratus for most of the coast later today. Cigs will then
lower tonight into Monday morning ahead of a frontal system.
Generally S/SW winds today, increasing later tonight.
KSEA...VFR conditions early this morning with just a few high
clouds. There remains the potential for fog development this
morning, particularly between 13-18z. Current probabilities are
approximately 35 to 40% for LIFR conditions during this period. S/SE
winds this morning are expected to become lighter generally after
12z, which may help promote fog development during the morning.
Stratus is also moving into the Southwest Interior as of 09z, but
expected to remain SW of the terminal this morning. VFR high clouds
this afternoon, with lowering cigs early Monday morning ahead of a
frontal system. S/SE winds this morning, becoming S/SW this
afternoon. JD
&&
.MARINE...Light southerly winds expected for the interior waters
today, with continued south to southeast winds for the Coastal
Waters. There may be a few localized gusts to SCA for the outer
Coastal Waters today, but expected to remain localized and not
widespread for a Small Craft Advisory. Southerly winds will then
increase tonight into Monday for all area waters as a front moves
across Western Washington. Small Craft Advisory has been issued for
the Coastal Waters with the south winds into Monday morning. South
winds will also increase for portions of the interior waters,
especially for Admiralty Inlet and areas of the northern inland
waters Monday morning. There may be a few SCA wind gusts for these
waters on Monday, and will have to monitor the need for any
additional SCA headlines. Otherwise, winds will become lighter
Monday night through Tuesday. Another, potentially stronger front,
is expected to move through the area Tuesday night into Wednesday.
Additional headlines possible for increasing south to southwest
winds during this period. A post-frontal westerly push is forecast
on Wednesday for the Strait of Juan de Fuca as well.
Seas 5 to 7 feet through today will build to 10 to 13 feet later
tonight into Monday. For this reason, Small Craft Advisories
continue for the Coastal Waters due to seas Monday into Monday
night. Seas are expected to then briefly subside below 10 feet later
Tuesday before increasing to near 10 feet Wednesday and potentially
into Thursday. JD
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 11 PM this evening to 11 PM PDT Monday
for Coastal Waters From Cape Flattery To James Island Out
10 Nm-Coastal Waters From James Island To Point Grenville
Out 10 Nm.
Small Craft Advisory from 5 AM to 11 PM PDT Monday for Coastal
Waters From Point Grenville To Cape Shoalwater Out 10 Nm.
Small Craft Advisory from 11 PM this evening to 8 AM PDT Tuesday
for Coastal Waters From Cape Flattery To James Island 10 To
60 Nm-Coastal Waters From James Island To Point Grenville
10 To 60 Nm-Coastal Waters From Point Grenville To Cape
Shoalwater 10 To 60 Nm.
&&
$$
NWS SEW Office Area Forecast Discussion