Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 110402
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
902 PM PDT Mon Aug 10 2020

.SYNOPSIS...Light low level onshore flow tonight into
Tuesday. Weak upper level trough moving through the area Tuesday
night into Wednesday. The upper trough slides east of the area
Thursday as a ridge builds into the area for the weekend for
warmer temperatures.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY/...Little change to the
forecast this evening. Low level onshore flow a little lighter
than previously thought so cut back on the morning cloud cover a
little Tuesday morning. Upper level trough moving into the area
later Tuesday into Wednesday. Best chances for showers looks to
be with some weak low level convergence near the east entrance of
the Strait Wednesday morning. Trough exits Wednesday night with
warming trend beginning Thursday. Felton

.LONG TERM /FRIDAY THROUGH MONDAY/...Previous discussion follows. A
system will slide north of the area into early Friday for
increased morning clouds but generally dry weather as upper
ridging builds into the Pacific Northwest. The upper ridge will be
over the area Saturday into Sunday for dry weather. Temperatures
will warm as well over the weekend with highs a decent bit above
average in the 80s, although will have to monitor if temperatures
will be warmer than that, especially on Sunday as the ridge axis
shifts slightly east. Guidance differs a bit late Sunday into
Monday as an upper trough approaches the area. Although
deterministic runs a bit different, ensembles suggest chance for
at least some precip around into Monday, so have shower chances
into the forecast. Temperatures a bit cooler on Monday as the
upper trough approaches the area.

&&

.AVIATION...West northwesterly flow aloft with weak low level
onshore flow through Tuesday night.

Just a few high clouds this evening. Stratus developing along the
coast overnight but with the weak onshore flow will have a hard
time getting east of Puget Sound Tuesday morning. Ceilings with
the stratus aob 1000 feet with the stratus dissipating by midday.
Increasing mid level clouds later Tuesday as upper level trough
approaches the area.

KSEA...just a few high clouds through Tuesday morning. Could see
low stratus deck off to the west 13z-17z Tuesday. Increasing mid
level clouds later Tuesday. North winds 4 to 8 knots becoming
variable around 12z. Southerly wind 4 to 8 knots after 16z. Felton

&&

.MARINE...Small craft advisory conditions persisting over the
outer coastal waters for the next 36 hours. Weak onshore flow
will increase later Tuesday into Tuesday night as upper level
trough moves into the area then ease again on Wednesday as the
trough moves east. Light onshore flow Thursday and Friday.

Small craft advisory westerlies in the central and eastern Strait
of Juan de Fuca tonight and again Tuesday night. Marginal small
craft conditions for the central and eastern Strait in the evening
hours Wednesday through Friday. Felton

&&

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

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 5 AM PDT Tuesday for Central U.S.
     Waters Strait Of Juan De Fuca-East Entrance U.S. Waters
     Strait Of Juan De Fuca.

     Small Craft Advisory until 5 AM PDT Wednesday 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.

&&

$$

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