Text Products for AFD Issued by SEW

Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 241653
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
953 AM PDT Fri Mar 24 2023

.UPDATE...-- Changed Discussion --
No significant changes to the forecast. Scattered
showers over the area today with a chance of thunderstorms along
the coast and interior south of Puget Sound. Cooler temperatures,
with lower snow levels through the weekend will allow for a
rain/snow mix, or even just snow showers over many lowland areas -
especially in the overnight or early morning hours. Very limited
accumulation, if any at all, is possible. Please see the aviation
and marine sections below for updates to those forecasts.-- End Changed Discussion --

.PREV DISCUSSION... -- Changed Discussion --/issued 311 AM PDT Fri Mar 24 2023/

.SYNOPSIS...An active pattern will remain over Western Washington
Friday through the weekend with an upper level trough over the
area. In addition to mountain snow, colder temperatures will
leave the door open for at least a chance of a wintery mix of
precipitation in the late night and early morning hours into
Sunday. Drier weather is in store early next week.-- End Changed Discussion --

.SHORT TERM /TODAY THROUGH SUNDAY/...More showers are expected
across western WA today and tonight with strong onshore flow and
a cool upper low overhead. The air mass is slightly unstable with
a chance of thunderstorms, especially near the coast. Up in the
mountains, snow levels remain low (around 1500 ft) with more
accumulating snow possible at all Cascades highway passes - a
Winter Weather Advisory remains in effect. With the cool air mass
in place, temperatures will fall below average.

The air mass will remain cool and showery as we move into
Saturday although total precipitation amounts will be lighter.
Snow levels Saturday morning will be quite low (500-1000 ft) and
we may see a rain/snow mix at times in the lowlands. However,
significant and/or widespread accumulations are not expected.

Western WA is in between systems on Sunday but we`re still under
a broad trough that covers much of the West. There`s still a
little moisture and lift over the area but the overall consensus
in the ensemble guidance is that precipitation amounts will be
light. A few cloud breaks will help nudge temps upwards with highs
near 50. 33

.LONG TERM /MONDAY THROUGH THURSDAY/...Model ensemble guidance
points toward drier weather as we move through early next week.
This is due to a strong system offshore that shifts inland to our
south Monday and Tuesday. The low level flow pattern will be
turning offshore for less cloud cover. This will help temperatures
climb closer to normal with highs in the mid 50s. Lows will still
be cool, though, and in the 30s. An upper ridge keeps drier
weather in the forecast as we move into mid week. The ridge then
flattens and the flow turns more zonal toward the latter half of
the week with a return to a wetter pattern possible. 33

.AVIATION...-- Changed Discussion --
Upper level trough will remain over western Washington
today with west to southwesterly flow aloft. The air mass is moist
and somewhat unstable. MVFR conditions in scattered showers are
expected to persist through the day with isolated thunderstorms
...especially coastal areas and SW interior. A convergence zone is
expected over Snohomish County later this afternoon.

KSEA...MVFR ceilings will persist across the terminal with scattered
showers. Any improvement to VFR late this afternoon is likely to be
brief. Surface winds southwesterly 10 to 15 knots...with higher
gusts this afternoon. Winds easing somewhat late this evening and
remaining S/SW 7 to 11 knots. 27-- End Changed Discussion --

.MARINE...-- Changed Discussion --
A surface trough will move inland today with onshore
flow across the area waters. Small craft advisories will continue
today most waters with gales in the strait. Onshore flow will
continue across the area waters this weekend, but will be weaker,
with surface high pressure residing well offshore and lower pressure
east of the Cascades. Flow will then turn offshore early next week
as a low digs southward over the offshore waters.

Seas of 14-17 feet across the coastal waters today will remain
elevated into Saturday before gradually subsiding back below 10 feet
late in the weekend. 14/27-- End Changed Discussion --

.HYDROLOGY...No river flooding expected in the next 7 days.

.SEW WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
WA...Winter Weather Advisory until 5 AM PDT Saturday for West Slopes
North Central Cascades and Passes-West Slopes South Central
Cascades and Passes.

PZ...Small Craft Advisory until 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-Grays Harbor Bar-West Entrance U.S.
Waters Strait Of Juan De Fuca.

Gale Warning until 7 PM PDT this evening for Central U.S. Waters
Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of
Juan De Fuca.

Small Craft Advisory until 11 PM PDT this evening for Admiralty
Inlet-Northern Inland Waters Including The San Juan Islands.-- End Changed Discussion --

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