708
FXUS66 KSEW 171616
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
916 AM PDT Fri May 17 2024

.UPDATE...Drier conditions expected today as subtle ridging builds
overhead. Lingering convergence zone activity over the central
Cascades will gradually fizzle out as the day progresses.
Temperatures are currently in the low 50s across the western WA
lowlands and should top out in the low 60s for today`s high. The
previous discussion is below along with an updated marine/aviation
section.



&&

.SYNOPSIS...Upper level troughing will continue to remain over
western Washington through the weekend, keeping showery and cooler
conditions around. A weak ridge looks to briefly build in the area
for the start of next week, before troughing returns for more cool
and showery conditions.

&&

.SHORT TERM /TODAY THROUGH SUNDAY/...Recent radar imagery depicts
a weakening convergence zone mainly focused over King/Snohomish
county with some enhanced shower activity. This convergence zone
will continue to weaken into the morning hours as upper level
troughing remains over western Washington. Some lingering showers
will be possible today but any hope for showers will likely be
focused in the Cascades, with mostly dry conditions in the
lowlands. Snow levels remain generally around 3000-3500 feet, with
some light snow showers in the higher peak of the Cascades. Clouds
may break up for some this afternoon, with high temps this
afternoon remaining slightly below average in the low 60s.

Another upper level low with a weak shortwave will then drift
southward into Saturday with another round of showers throughout
majority of the area, with high temps a bit cooler in the upper
50s.

A brief but weak transient ridge will nudge into our area into
Sunday evening for generally dry conditions in the interior and
high temps in the lower 60s.

.LONG TERM /MONDAY THROUGH THURSDAY/...Brief dry conditions will
continue into Monday before another upper level low from British
Columbia moves south into western Washington on Tuesday - with
the return of unsettled weather. Showery and cool weather will
continue yet again into the long term period with temperatures
just slightly below normal.

Mazurkiewicz


&&

.AVIATION...Northwesterly flow will persist aloft today as an
upper level trough over WA continues to push east and a ridge of
high pressure remains situated over the NE Pacific. Post- frontal
onshore flow will continue today and radar this morning shows
some lingering showers pushing into the north and central
Cascades. Showers will continue to diminish through the morning
hours. Conditions mainly VFR this morning, with a few localized
spots of MVFR. For MVFR areas, expect improvement towards VFR
between 16-18Z and for VFR conditions to persist through much of
the day. The low level air mass will remain moist, and with
onshore flow continuing, expect to see another round of lower
ceilings to develop overnight into Saturday morning.

KSEA...Expect clouds at 2000 ft to scatter and for VFR conditions
to persist through much of the day. Winds generally persisting
from the S/SW at 10-14 kt. 14


&&

.MARINE...High pressure over the NE Pacific will maintain onshore
flow across western WA through the weekend. Strongest winds will
be over the Strait of Juan de Fuca with Small Craft Advisory winds
extending through late tonight. The next frontal system will reach
the region early next week.

Seas hovering at 9-11 ft across the coastal waters this morning.
Expect seas to continue to subside towards 7-9 ft this afternoon
and to 5-7 ft over the weekend. 33/14


&&

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

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 11 AM PDT this morning for Admiralty
     Inlet-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-Northern
     Inland Waters Including The San Juan Islands-West Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory until 5 AM PDT Saturday for Central U.S.
     Waters Strait Of Juan De Fuca-East Entrance U.S. Waters
     Strait Of Juan De Fuca.

&&

$$