195
FXUS66 KSEW 032126
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
226 PM PDT Thu Apr 3 2025

.SYNOPSIS...Upper ridging over the Pacific Northwest will bring
dry weather through Saturday. A front will move through Sunday for
increasing rain. Troughing early next week will bring showers and
cooler temperatures.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...A mix of clouds and
sunshine this afternoon with temperatures in the 50s. An upper
ridge will continue to build over Western Washington into Friday
for dry conditions. Clear skies tonight, along with lighter winds,
may result in areas of fog, mainly for Olympia southwards, as
well as along the Chehalis River Valley. In addition, temperatures
are expected to drop into the low to mid 30s for these
aforementioned areas. This may result in frost development,
especially in areas away from the water where clear skies
continue. A Frost Advisory has been issued for these zones tonight
into early Friday morning.

High clouds may be around on Friday at times, but mostly sunny
conditions are expected. A bit more in the way of high clouds on
Saturday as a frontal system moves towards Western Washington.
High temperatures in the 60s on Friday will warm into the upper
60s and low 70s for some areas on Saturday.

Rain chances will increase Saturday night, initially along the
Olympic Peninsula, before rain moves into Puget Sound during the
day on Sunday. Temperatures on Sunday will be about 10 degrees
cooler in the mid to upper 50s.

.LONG TERM /MONDAY THROUGH THURSDAY/...Troughing will continue
over Western Washington early next week. This will result in
continued unsettled weather, at least through early Wednesday.
Showers will be around during this period, and can`t rule out a
thunderstorm either Monday afternoon (NBM probabilities around
10-20%). Snow levels will drop near 3500 to 4500 feet later Monday
into early Wednesday, which may result in light to moderate snow
accumulations for higher elevations. Ensembles suggest that
ridging may try to build into the interior Pacific Northwest on
Wednesday. However, due to continued troughing offshore, kept NBM
probabilities of precip at this point, resulting in continued
shower chances. Temperatures will be near to slightly below normal
early next week. JD

&&

.AVIATION...North winds aloft as an upper level ridge begins to move
eastward towards western Washington. A scattered cumulus field has
allowed for VFR conditions to prevail across the area. VFR
conditions will continue through tonight as cloud cover continues to
break up. Some high clouds will move in overnight, which may limit
more widespread fog development tonight into early Monday morning.
The best chances for fog development look to be around the south
sound and Chehalis valley, through other river valleys and fog-prone
coastal areas may see some patchy fog early Monday morning. Patchy
frost may also limit fog development around OLM and southward. All
in all, any fog that develops will be short-lived and VFR conditions
should continue into Friday. Light north-northwesterly winds will
turn to northeasterly this evening before becoming calm overnight.
Winds again tomorrow will be light northwesterly (5 kt or less).

KSEA...VFR conditions prevail through the majority of the TAF
period. There is a 15-25% chance of seeing some low clouds/fog at
the terminal between around 12-18Z Friday, through this will likely
be short-lived if it does develop. There are several limiting
factors (mentioned above) that decrease forecast confidence in fog.
Northwest winds will veer to northeast this evening (up to 5 kt),
becoming light and variable/easterly (5 kt or less) to calm
overnight. Winds will resume as north/northwesterly, up to 5 kt,
during the day Friday.

62

&&

.MARINE...Broad high pressure over the northeast Pacific will remain
in place through Sunday, continuing the period of light winds and
seas. The next frontal system will move through the waters on
Sunday, bringing a quick round of breezy winds which may require
headlines. Additional systems look to traverse the area waters early
next week, keeping breezy conditions in the forecast.

Combined seas 3 to 5 feet through the rest of the week and into the
weekend. Seas will start to gradually build upwards Saturday night
into Sunday, reaching 10 to 13 feet Sunday and remaining in the 8 to
12 ft range through early next week.

62

&&

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

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Frost Advisory from midnight tonight to 9 AM PDT Friday for
     Lowlands of Lewis and Southern Thurston Counties-Middle
     Chehalis River Valley-Olympia and Southern Puget Sound.

PZ...None.
&&

$$