Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 260359
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
859 PM PDT Mon Mar 25 2024

.UPDATE...Satellite imagery and doppler radar show showers over
Western Washington this evening with most of the shower activity
from Seattle northward. A few showers offshore with a bit of a
break Tuesday morning for the lowlands with light showers
continuing in the mountains. Precipitation increasing again
Tuesday night into Wednesday morning as rain out ahead of the
next frontal system moves into the area. Snow levels around 3500
feet so expect a decent amount of new snow in the higher
elevations of the Olympics and Cascades into Wednesday night.
Current forecast has the trends covered. No update this evening.

&&

.SYNOPSIS...Cloudy conditions with periodic rain and mountain snow
showers will continue through Tuesday as a series of weak fronts
cross the region. A stronger and wetter system will bring in more
widespread lowland rain and mountain snow alongside breezy winds
through at least Thursday. Drier and warmer conditions are on
track to return by the weekend.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY/...A weak and disorganized
frontal system moved into western Washington this afternoon. Light
to locally moderate shower activity which will persist tonight
into Tuesday. Snow levels are hovering between 3000-4000 feet
resulting in some occasional light snowfall at the mountain
passes. High-res models point to the development of transient
convergence zone activity at times across Snohomish and northern
King counties overnight through Tuesday before a brief break in
the precipitation arrives Tuesday night.

A more organized system will spread widespread precipitation and
breezy conditions across the region Wednesday through Thursday.
Precipitation totals of 1.0-1.5 inches across the western Olympic
Peninsula and lower amounts across the Puget Sound Lowlands and
Cascades. Snow levels will rise from around 2500 feet to 4000-4500
feet during this event, resulting in some additional light snow
accumulations at the passes and heavier snow at higher elevations
above 4500 feet. There will be a 20-30% chance of thunderstorms
along the coast Wednesday afternoon through Thursday, with lower
probabilities elsewhere.

.LONG TERM /FRIDAY THROUGH MONDAY/...The upper level low
associated with the Wednesday/Thursday system will dig south along
the west coast Friday, taking the bulk of the energy with it. This
will allow ridging to begin to nose into the region this weekend,
resulting in somewhat drier and warmer conditions over the
weekend and potentially into early next week.
-Wolcott-

&&

.AVIATION...A weakening occluded front continues to advance
eastward as an upper-level ridge continues to drag down northwest
flow aloft over the region. Rain showers continue across the region,
and will continue through the first part of Tuesday. Ceilings are
beginning to drop to MVFR, with only a few terminals still in VFR
this evening. Post front, some convergence showers may linger over
Jefferson/Island/Snohomish counties Tuesday morning, and afternoon.
Ceilings will improve to VFR late Tuesday morning, with breaks in
the clouds Tuesday afternoon as an upper-level ridge passes over.
Surface winds will remain southwesterly at 10 to 15 kt.

KSEA...MVFR at the terminal this evening, likely continuing
throughout the night. Vicinity showers will continue through Tuesday
morning. Ceilings will improve to VFR Tuesday afternoon. Winds out
of the southwest diminishing to around 5 kt overnight.

HPR/Kristell

&&

.MARINE...Onshore flow continues ahead of a weak occluded front
passing through the region tonight. Showers have been ongoing but
are not expected to impact visibilities. A more potent surface low
brings more widespread precipitation, and gusty southerly winds late
Tuesday into Wednesday. Gale warnings have been issued for all
coastal water zones, as well as the East Strait of Juan de Fuca.
Small craft advisories have been issued for the West & Central
Strait of Juan de Fuca, as well as the Admiralty Inlet/Northern
Inland Waters. Additional gusty winds are expected Thursday with an
additional front swinging through.

Seas 5 to 7 ft at 15 seconds will build tomorrow night to around 10
to 12 ft, increasing again Wednesday night into Thursday to 13 to 15
ft before easing below 10 ft by the end of the week.

HPR

&&

.HYDROLOGY...A frontal system arriving on Wednesday is expected to
produce enough rainfall to push the Skokomish River in Mason
county above action stage. At this time flooding is not forecast,
but we will continue to monitor that potential. Significant rises
on other area rivers is not expected at this time.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 2 AM to 5 PM PDT Wednesday for Central
     U.S. Waters Strait Of Juan De Fuca-West Entrance U.S.
     Waters Strait Of Juan De Fuca.

     Gale Warning from 2 AM to 8 PM PDT Wednesday for East Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 5 AM to 8 PM PDT Wednesday for
     Admiralty Inlet-Northern Inland Waters Including The San
     Juan Islands.

     Gale Warning from 10 PM Tuesday to noon 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.

&&

$$


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