620
FXUS66 KSEW 030330
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
830 PM PDT Thu May 2 2024

.SYNOPSIS...Dry and mostly clear conditions through tonight. A
wetter storm system will move into western Washington on Friday,
and cool and unsettled conditions will prevail through the
weekend and early next week.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...Clouds and showers over
the higher terrain have quickly dissipated with the sun setting
this evening. We`ve got a mostly clear and cool night ahead then
clouds increase through the day on Friday ahead of the next frontal
system. Rain reaches coastal areas and the Olympic Peninsula by late
Friday afternoon, but interior areas east of Puget Sound look to
remain mainly dry until perhaps midnight or so. Forecast trends look
on track with no anticipated evening updates. Previous discussion
follows with updates to marine/aviation portions.  27

Weak high pressure is bringing sunny and dry conditions to much of
western WA today with temps in the 50s and 60s. There are a few pop-
up showers over the Cascades and cells may drift into the foothills
this afternoon with easterly steering flow aloft. Shower activity
will fade away this evening as the ridge axis shifts inland.

The ridge exits east on Friday while a deep upper low develops
offshore. A frontal system will spread rain to the coast mid to
late morning with rain spreading inland during the afternoon and
evening. The air mass will remain mild, though, under deep
southerly flow. Temperatures in the interior will reach the mid to
upper 60s ahead of the rainfall.

The weekend is looking cool and showery as the deep upper low
slowly tracks inland. There`s plenty of wrap-around moisture
clipping western WA on Saturday with little break in the action.
Highs on Saturday are only in the low to mid 50s. Onshore flow
will increase on Sunday keeping western WA cool, cloudy and
showery. It`ll be windy too with gust around 20-30 mph
(especially around the south sound and Strait of Juan de Fuca). 33

.LONG TERM /MONDAY THROUGH THURSDAY/...Western WA remains under
solid onshore flow through early next week, keeping us cool and
wet through the period. The air mass is slightly unstable on
Monday and added lift from a trough axis may trigger a few
thunderstorms too. Onshore flow eases by midweek and drier N/NW
flow may give us a little break. Warmer and drier weather is
favored for the latter half of the week with high pressure. 33

&&

.AVIATION...Winds aloft northwesterly becoming southwesterly
tomorrow afternoon as a small upper-level ridge moves over the area
tonight followed closely behind a larger trough. Mostly clear skies
across western Washington this afternoon as high pressure moves into
the NE Pacific. Northerly to onshore flow will continue to weaken
this evening. The wind will shift back to light
offshore/southeasterly late tonight as the next frontal system
approaches the region. Winds may be gusty along the coast tomorrow
afternoon. Cigs expected to remain VFR through most of the TAF
period. Mid to high level clouds will filter in early tomorrow
morning ahead of an incoming frontal system, with lower ceilings
(but remaining VFR) tomorrow evening. Some MVFR may be possible
along the coast and towards OLM at the end of the period. Showers
will reach the Pacific coast late tomorrow morning into tomorrow
afternoon, nor moving into the interior until late tomorrow
afternoon and evening. Areas north of the Seattle area may not see
any significant rain in this TAF period.

KSEA...VFR conditions through the TAF period. High clouds move in
this evening, with lower ceilings developing into the end of the TAF
period. Light northwest winds veering to light southeasterly early
this evening as the next frontal system approaches. Winds will pick
up to southwesterly 8-10 kt by tomorrow afternoon. Rain is not
expected until tomorrow afternoon into tomorrow evening, and will
only be showery in nature.

LH

&&

.MARINE...Weak high pressure over the area waters continue into
tonight for overall calm conditions. The next frontal system will
move into the area waters Friday into Saturday, where southerly
winds will increase across the outer coastal waters through Friday
evening. As such, a Small Craft Advisory remains in effect for the
coastal waters farther than 10 NM. Several westerly pushes down the
Strait of Juan de Fuca look likely this weekend into early next week
with a significant onshore push following the frontal system.
Another system looks to arrive in the region late Sunday into Monday.

Combined seas across the coastal waters will generally hover between
3-5 ft through Friday, before increasing towards 6-7 ft over the
weekend. Confidence is still high regarding seas approaching 9-11 ft
Monday night into Tuesday.

Kristell/LH

&&

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

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 9 AM to 7 PM PDT Friday for 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.

&&

$$