Forecast Discussion
Forecast Discussion for SEW NWS Office
433
FXUS66 KSEW 170253
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
753 PM PDT Sun Mar 16 2025
.UPDATE...Radar shows scattered shower activity mainly north of
the Puget Sound continuing to shift northeastward this evening.
Weak troughing over the region will bring a few shortwaves inland,
maintaining scattered showers into late Monday. The current
forecast remains on track with no significant impacts and no
updates.
&&
.SYNOPSIS...Showery weather will continue through Monday. A brief
break in the wet weather is possible on Tuesday as an upper level
ridge briefly moves over the region. A series of systems will then
move into the region mid to late week for additional rounds of
lowland rain, mountain snow, and breezy winds at times.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY/...Shower activity this
evening will likely bring some additional snow accumulations to
the mountain passes into Monday, but expect overall amounts to be
rather light. Showers will gradually decrease in coverage through
this evening.
Broad upper level troughing over the northeastern Pacific will
move into the West Coast tonight into Monday. Weak perturbations
from this trough will help re-invigorate shower activity across
the region on Monday morning. With increasing onshore flow,
expect a convergence zone to develop across the central Sound
near midday Monday. While snow levels will start out around
1500-2000 feet in the morning, any heavier banding within the
convergence zone could temporarily push snow levels down a bit
further for areas along the Cascade valleys. Locally higher snow
accumulations will be possible for the mountains under any banding.
Shower activity will gradually decrease into Tuesday as the broad
upper trough moves off to the east and an upper level ridge
starts to nudge from the northeast Pacific.
A brief break in the wet weather is expected on Tuesday before
more active weather returns on Wednesday. With snow levels
generally hovering between 2000-3000 feet, expect another round of
snow for mountains and rain for the lowlands. Winds will become
gusty as this system makes its way inland, especially for areas
along the coast and for Admiralty Inlet northward.
.LONG TERM /FRIDAY THROUGH MONDAY/...Active weather will
continue through the long term as a series of systems moves into
western Washington. The next system is on tap to move into the
region Thursday into Friday, followed by another one over the
weekend. Additional rounds of lowland rain, mountain snow, and
breezy winds will be likely across the area, though the system
over the weekend may bring wetter conditions and rising snow
levels. 14
&&
.AVIATION...Westerly flow aloft will continue through Monday with
broad troughing across the West. VFR for most areas this evening,
with isolated MVFR to IFR conditions...mainly in locations seeing
lingering showers. These conditions will linger into the overnight
hours before cigs are expected to lower Monday morning towards MVFR
for areas along the coast and east of Puget Sound. Localized IFR
cannot be ruled out as well, especially for those locations more
prone to lower cigs. Fog development should be limited due to
continued cloud cover, however, lower vsbys are possible, mainly
around KPWT and KOLM if there is sufficient clearing. Otherwise,
cigs will improve to VFR for Monday afternoon. A few showers will
continue into Monday, with a convergence zone developing around King
to Snohomish County Monday afternoon or early evening. S/SW surface
winds will become lighter tonight, before increasing W/SW on Monday.
.KSEA...VFR cigs are expected to continue into early tonight. Cigs
are expected to lower towards MVFR Monday morning. Current
probabilities of MVFR cigs range 25 to 30% from 12 to 18z.
Otherwise, VFR cigs for Monday afternoon. S/SW winds through this
evening, with periodic gusts to 20 to 25 kts. South winds Monday
morning may transition more N/NW later Monday afternoon (after 22z)
as a convergence zone develops to the north. JD/18
&&
.MARINE...A weak surface trough will continue over the waters into
early Monday before ridging builds over the offshore waters later
Monday into Tuesday. Onshore flow will increase Monday afternoon
into Monday evening, resulting in SCA wind gusts through the central
and eastern Strait of Juan de Fuca. South winds will then begin to
increase later Tuesday ahead of a stronger frontal system that will
move through on Wednesday. Gale force winds are currently forecast
for the Coastal Waters on Wednesday due to increased south winds,
with additional headlines likely for portions of the interior
waters. Winds will ease Thursday morning, before increasing again
Thursday night into Friday with another weather system.
Seas of 10 to 12 feet will briefly subside below 10 feet Monday
afternoon through early Wednesday. Seas will build above 10 feet
Wednesday, and likely remain above 10 feet into the weekend. JD
&&
.HYDROLOGY...At this time, flooding is not expected across most
of the area`s rivers over the next 7 days. The exception remains
the Skokomish River, which could enter flood stage late in the
week as a series of wet systems move across the area.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 5 AM PDT Monday 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.
Small Craft Advisory from 3 PM Monday to midnight PDT Monday
night for Central U.S. Waters Strait Of Juan De Fuca-East
Entrance U.S. Waters Strait Of Juan De Fuca.
&&
$$
NWS SEW Office Area Forecast Discussion