016
FXUS66 KSEW 132119
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
219 PM PDT Sat Jul 13 2024

.SYNOPSIS...An upper level ridge remains over Western Washington
through the weekend into next week with continued low level
onshore flow. This will maintain above normal temperatures, with
only subtle variations in the strength of the marine pushes each
night.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...Zonal flow will remain in
place today as a flat upper level ridge remains parked over
western Washington. Lingering marine stratus over coastal
locations will dissipate by this afternoon, joining the rest of
the area in clear skies. Interior locations will have temperatures
warm into the mid 80s, while coastal locations will see highs
ranging from the mid 60s to the lower 70s.

Temperatures will continue to remain above normal through the
interior through the short term, while this persistent pattern
of light onshore flow will continue through the first half of
next week.

Zonal flow and the aforementioned weak upper ridge will shift
eastward on Tuesday, opening the way for a longwave trough to
nudge closer to the region.

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...As the ridge shifts
eastward into Wednesday, a longwave trough offshore will introduce
a dry south/southwesterly flow throughout the area. This may open
the door to increased convection chances in the Cascades as a
weak front attempts to cross over the region. Ensemble guidance
showing low probabilities at this time, but it is something to
monitor over the next couple of days. As of now, the most likely
outcome would be continued warm and dry conditions, but some light
precipitation may be possible during this time frame (Cascade
focused).

An upper level ridge to the east looks to intensify through the
remaining of the long term period, with temperatures still staying
above average, in the mid to upper 80s.

Mazurkiewicz

&&

.AVIATION...Mostly VFR. Another marine push with onshore flow will
cause localized IFR/LIFR along the coast late tonight into Sunday
morning. Forecast models continue to show the marine stratus layer
expanding inland through the early morning, though KOLM is favored
to stay VFR with the stratus holding to the west. Stratus will
slowly evaporate by 19z Sun with KHQM once again seeing VFR
conditions Sun afternoon. Winds generally N-NW 5 to 10 kt this
afternoon, decreasing overnight and shifting to W-SW by Sunday
afternoon.

KSEA...VFR under clear skies. Light north to northwest winds 5 to 10
kt this afternoon, decreasing overnight and shifting S-SW by 12z
Sunday morning. Low chance (20% probability) of a strong enough
marine push for MVFR ceilings overnight Sunday into Monday morning,
but confidence is low.

15

&&

.MARINE...Little change in the weather pattern with high pressure
situated offshore and a thermal trough over eastern Washington. A
Small Craft Advisory continues through today over the outermost
coastal waters for gusty northwesterly winds up to 25 kt, with the
highest speeds concentrated farther than 30-40 NM offshore.
Diurnally driven pushes of westerly winds down the Strait of Juan de
Fuca will occasionally be strong enough to warrant additional
headlines into next week, with the next strongest push expected to
be Sunday evening.

Seas 6 to 8 ft across the coastal waters will decrease Sunday night
into Monday to around 4 to 6 ft through the beginning of next week.

15

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 11 PM PDT this evening 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.

&&

$$