Washington State Forecast Discussion

Western Washington


970
FXUS66 KSEW 312240
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
340 PM PDT Tue Mar 31 2026

.SYNOPSIS...
Cloudy conditions will persist today ahead of an incoming
frontal system that will bring lowland rain, mountain snow, and
breezy winds to the region on Wednesday. Showers will taper off
over the mountains on Thursday before a high pressure ridge
brings much warmer and drier conditions over the weekend and
into early next week.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY/...
Upper level flow will continue to turn southwesterly today as a
low pressure system lowers along the British Columbia coast.
Clouds will continue to increase today ahead of this incoming
system, with potential for light shower activity moving
northward later this evening. Temperatures are on track to peak
near normal today across the region, with highs in the mid to
upper 50s across the lowlands.

As the low pressure system continues to progress southward along
the Pacific Coast, the storm system will swing a cold front
across western Washington on Wednesday. Winds will ramp up early
Wednesday morning, with the strongest wind gusts reaching 35-45
mph along the Pacific Coast, through the Strait of Juan de Fuca,
and from Whidbey Island northward across the northern interior.
Elsewhere, winds will be breezy, with gusts of 25-35 mph. Winds
will remain elevated through the early afternoon before easing
throughout the rest of the day. Precipitation will spread
inland along the frontal passage Wednesday morning, with steady
rain across the lowlands through the afternoon and showers
continuing through the evening. The lowlands will see generally
0.25 to 0.75 inches of rainfall through Wednesday night. In
addition, snow levels starting at pass level on Wednesday
morning will rise to 4000-4500 feet throughout the day before
falling below pass level once again early Thursday. This will
result in about 4-8 inches of snow accumulation through the
Cascade passes, and a Winter Weather Advisory has been issued.

The parent low pressure system will shift inland over Oregon on
Thursday, with potential for wrap around moisture to allow for
continued light snow over the Cascades. Conditions will dry out
across the lowlands on Thursday, with cloudy skies and some
afternoon sun breaks. Wednesday and Thursday will see cooler
temperatures, with highs peaking in the upper 40s to low 50s
across the lowlands.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Models remain in good agreement over warmer and drier conditions
settling over the western US into the weekend and early next
week as a high pressure ridge builds over the region. A weak
system may try to overrun the building ridge over the weekend
and bring light rain to the north coast, but forecast models
continue to trend drier. While there are model differences
beyond the weekend, ensembles favor warm and dry conditions into
early next week. Temperatures are expected to peak in the low to
mid 60s over the weekend away from the immediate coast, with
potential for some areas along the Cascade foothills to reach 70
degrees on Monday as warming continues. A pattern change looks
to arrive towards the middle of next week, but the details
remain uncertain at this time.

15

&&

.AVIATION...
Southwesterly flow aloft as an system approaches western
Washington tonight and into Wednesday. VFR conditions at all
terminals this afternoon with high clouds streaming in overhead
of the next front. Widespread rain will enter the coast around
10z with the return of MVFR/IFR ceilings. Rain will start to
reach the interior around 12z-15z, with likely widespread MVFR
conditions and some areas IFR (OLM, PWT). Westerly winds this
afternoon turning southerly overnight and increasing to 8 to 12
knots for much of the area. Terminals like KHQM and KBLI will
likely see stronger southerly winds, around 10 to 15 knots with
gusts up to 25 kts.

KSEA...VFR conditions this afternoon with passing high clouds.
Westerly winds turning more southerly after 00z. Rain
approaching the terminal early Wednesday morning (12-15z) with a
40% chance of MVFR conditions throughout the early morning.
Will likely see bouncing from VFR/MVFR throughout Wednesday
morning in passing rain showers. Southerly winds increasing to 8
to 12 knots Wednesday morning.

Mazurkiewicz

&&

.MARINE...
Surface high pressure continues today with generally light
winds over the area waters. A low pressure system will move over
the area waters tonight and into Wednesday for increasing
southerlies over much of the waters. A Gale Watch has been
upgraded to a Gale Warning for higher confidence in gusts
exceeding 35 kts over all of the coastal waters. A Gale Warning
is also out for the East Entrance, where gusts and sustained
will around 30 to 35 kts at times. A small craft advisory has
been issued for the Northern Interior Waters and Admiralty
inlet for enhanced southerlies.

Broad high pressure will redevelop on Thursday and into Friday,
bringing lighter winds and quieter marine conditions.

Coastal seas remaining 3 to 5 feet throughout today. Seas will
then build up to 9 to 11 feet Wednesday morning. Seas will
remain elevated into Thursday before decreasing on Friday and
into the weekend, back down to 3 to 5 feet.

Mazurkiewicz

&&

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

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Winter Weather Advisory from 11 AM Wednesday to 11 PM PDT
Thursday for Cascades of Pierce and Lewis Counties-
Cascades of Snohomish and Northern King Counties-Cascades
of Southern King County-Cascades of Whatcom and Skagit
Counties.

PZ...Gale Warning from 4 AM to 5 PM PDT Wednesday for East Entrance
U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory from 4 AM to 5 PM PDT Wednesday for
Admiralty Inlet-Northern Inland Waters Including The San
Juan Islands.

Gale Warning from 1 AM to 11 AM PDT Wednesday 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.

&&