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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS66 KSEW 281000
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
300 AM PDT Tue Mar 28 2023

.SYNOPSIS...
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Warmer and drier weather will persist across much of
western Washington through midweek as a storm system offshore
progresses southward towards California. A return to wetter and
cooler conditions is expected the latter half of the week and
into the weekend as a seasonally strong frontal system moves into
the region.
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&&

.SHORT TERM /TODAY THROUGH THURSDAY/...
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A strong upper level low
and its associated surface cyclone are currently situated well
offshore the Oregon waters this morning. This feature will continue
to track southward towards California throughout the day. Radar shows
shower activity gradually making its way northward into the
southern fringes of the CWA early this morning. In addition,
cross- Cascade gradients have started to pick up overnight, making
for gusty conditions along the Cascade passes and portions of the
East Puget Sound lowlands at times. East winds will persist at
these locations through the day, generally at 25 to 35 mph, with
gusts 40-50 mph possible at times- so a wind advisory remains in
effect. Expect gradients to peak by mid- morning and for winds to
gradually ease again this evening. Elsewhere across the lowlands,
expect conditions to be breezy at times through the day. With
easterly/downslope flow off the Cascades, expect the majority of
western Washington to experience another dry day today. However,
as latest radar suggests, the exception will be the southern
fringes of the forecast area (mainly Lewis, Thurston, Grays
Harbor, and Pierce counties), where some shower activity will
continue to move northward as wrap- around moisture from the low
continues to make its way into the area. Overall precipitation
amounts look to remain rather light, with most spots only expected
to receive a couple hundredths of an inch. Exceptions would be
the east side of the Olympics should moisture make it far enough north
and the southern portion of Lewis county- where amounts may
locally be higher. Cloud cover will continue to advect northward
from the low through the day for the southern counties of the CWA,
but overall expect areas to the north to see some sun today as
high cloud cover breaks up over the area. Highs today will continue
to warm a few degrees, topping out in the upper 50s to near 60.
Showers across the southern portion of the forecast area will then
taper and become confined to the southern Cascades tonight into
Wednesday.

The upper level low will continue to sink southward towards
California on Wednesday, allowing for an upper level ridge to
nudge into western Washington from the west. Wednesday still
looks to be the nicest day of the week, with afternoon highs
expected to warm a few degrees from Tuesday - topping out in the
upper 50s to low 60s across the area. Clouds will scatter as well,
making way for sunny conditions.

A weak trough will then move into the region on Thursday. Although
moisture continues to look rather limited with this feature,
expect it to spark some shower activity across the region -
primarily along the coast and across higher terrain. Temperatures
will cool a couple degrees and look to only top out in the upper
40s along the coast and low to mid 50s across the interior. This
will mark the start of a much cooler and wetter period of weather
heading into Friday and the weekend. 14

.LONG TERM /FRIDAY THROUGH MONDAY/...An area of low pressure will
strengthen across the Gulf of Alaska on Friday, ejecting a
shortwave towards the Pacific Northwest. This feature will push an
associated surface front into the region on Friday, bringing with
it the next best chance for widespread rain and mountain snow.
Latest guidance still shows the frontal system approaching the
coast Friday night and moving inland overnight into Saturday. Snow
levels will fall back down to below pass level, so can expect
periods of heavy snow for the mountains at times. Showery and cool
weather will continue through the weekend and into early next
week in its wake. High temperatures will generally trend in the
upper 40s to low 50s and overnight lows will be in the low to mid
30s. 14
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&&

.AVIATION...
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Deep, low pressure spins offshore today with
precipitation mainly to our south. The flow aloft is S to SE. The
low level air mass is dry with mainly mid/high clouds over western
WA. VFR conditions expected.

KSEA...VFR today with mid/high clouds. Gusty E/NE winds to 25 kt
through 00z. 33
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&&

.MARINE...
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Strong offshore flow will continue today as a 980
mb low spins south over the offshore waters (along 130W).
Strongest winds will be over the Western Strait of Juan de Fuca
and adjacent Coastal Waters - a Gale Warning is in effect. Winds
will ease this afternoon and evening. Northerly flow develops
Wednesday then turns onshore Wednesday night with possible Small
Craft Advisory winds down the strait. The flow gradually turns
southerly ahead of another frontal system that will move across
the region Friday. 33
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&&

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

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
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WA...Wind Advisory until 5 PM PDT this afternoon for East Puget Sound
     Lowlands.

PZ...Gale Warning until 2 PM PDT this afternoon for Coastal Waters
     From Cape Flattery To James Island Out 10 Nm-West Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 2 PM this afternoon to 6 PM PDT this
     evening for Coastal Waters From Cape Flattery To James
     Island Out 10 Nm-West Entrance U.S. Waters Strait Of Juan
     De Fuca.

     Small Craft Advisory until 9 PM PDT this evening for Central
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory until 5 AM PDT Wednesday for Northern
     Inland Waters Including The San Juan Islands.

     Small Craft Advisory until 6 PM PDT this evening 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 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-Puget Sound and Hood Canal.
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&&

$$