FXUS66 KSEW 192126
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
226 PM PDT Tue May 19 2026

.SYNOPSIS...
High pressure aloft will begin to rebuild across Western
Washington on Wednesday and remain in place into Friday for a
return to some sunshine and warmer temperatures. The ridge will
weaken over the upcoming holiday weekend for a cooling trend and
a chance of rain by Memorial Day.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
Considerable cloud cover and a few light showers remain in 
place across the region this afternoon as a weak front 
dissipates over the area. A building upper ridge on Wednesday 
will lead to clearing skies and warmer temperatures. The ridge 
remains firmly in place offshore into Thursday with low level 
onshore flow weakening. Interior temperatures will warm a few 
degrees, but coastal area temperatures will likely stay fairly 
static with night and morning clouds hanging around and an 
afternoon sea breeze.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
The upper ridge axis offshore begins to weaken on Friday with
low level onshore flow picking up a notch late in the day.
Interior temperatures should be similar to those of
Thursday...upper 60s to mid 70s...while coastal areas remain
mostly in the lower 60s. The ridge is expected to flatten by
Saturday for slightly cooler temperatures to begin the weekend.

The weekend looks like a tale of two halves. Ensemble height 
anomalies agree that a deepening upper trough over the 
Northeast Pacific will begin a transition toward cooler 
temperatures and possible precipitation, but the speed of 
transition is up for debate. In general, the Euro and Canadian 
suite of solutions are more agressive with the troughs arrival 
while the GFS is less so. Sunday should feature additional 
cooling and cloud cover with precip chances increasing areawide 
Sunday night into Memorial Day.

27

&&

.AVIATION...
Upper ridging offshore will continue to lead to N/NW flow aloft
over western Washington this afternoon. A mixed bag of
conditions out there this afternoon as low clouds continue to
linger. Will continue to see a mix of localized MVFR/IFR
conditions at areas along the coast, plus lower prone terminals
such as KPWT and KPAE. Conditions likely to recover to VFR for 
most area terminals later this afternoon - with the exception 
for coastal terminals like KHQM, where MVFR conditions will 
remain (85% chance). S/SW winds 5 to 10 knots this afternoon 
will start to turn northerly 00Z-03Z and will maintain the same 
speeds. MVFR/IFR conditions return early Wednesday morning 
(09z-15z) for interior terminals. 

KSEA...VFR conditions this afternoon with S/SW winds 5 to 10
knots. Latest guidance shows a shift to N/NE winds 00Z-03Z. Mid
to high level clouds will stuck around throughout the evening,
with a 40 to 60% chance of MVFR conditions returning tonight 
and lasting throughout Wednesday morning, with VFR returning 
around 19z-21z.

Mazurkiewicz

&&

.MARINE...
Surface high pressure offshore will continue onshore flow
throughout the area waters through majority of the week. A small
craft advisory remains in effect for all outer coastal water
zones, mainly for elevated seas. Can expect another westerly
push down the Strait of Juan De Fuca tonight, where a small
craft advisory is also in effect. We'll see diurnally driven
pushes down the Strait through the end of the week. A system on
Friday and Saturday could bring a round of elevated seas and
winds to the coastal waters. 

Coastal seas 6 to 8 feet this afternoon will increase to 8 to 10
feet tonight into Wednesday. Seas will then level to 7 to 9 feet
throughout Thursday, before rising above 10 feet Friday and into
the weekend.

Mazurkiewicz 

&&

.HYDROLOGY...
The daily hydrology discussion has ended until the start of the
next rainy season; it will only be updated during this time as 
needed.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 5 PM this afternoon to 5 AM PDT 
     Wednesday for Central U.S. Waters Strait Of Juan De Fuca-
     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 Point Grenville To Cape 
     Shoalwater 10 To 60 Nm-East Entrance U.S. Waters Strait 
     Of Juan De Fuca.

&&

$$