Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 040521

Area Forecast Discussion
National Weather Service Seattle WA
920 PM PST Sun Dec 3 2017

.SYNOPSIS...High pressure will gradually strengthen over the
region Monday and Tuesday. A persistent upper ridge will keep the
weather dry through the week ahead. Areas of fog and low clouds are
likely at times in the lowlands, but the mountains will be clear.


.SHORT TERM...High pressure will build and the air will stabilize
and dry through Monday and Tuesday. The upper ridge building over
the west part of North America will peak in strength around midweek.
Areas of fog and low clouds are likely to develop over the lowlands
while the mountains and coast should be in the clear--except near
the Cascade Crest where cool air and fog is likely to push into the
passes at times from Eastern Washington.

.LONG TERM...Little change from the first half of the week: The
strong ridge will remain over the region during much of this period.
The ridge weakens a bit into the end of the week, but not enough to
prevent the region from remaining dry with weather systems deflected
far from the area. In fact, the upper ridge could strengthen again
early next week. The air will be stable with areas of low clouds and
fog and air quality concerns at times.


.AVIATION...An upper ridge will build in from the west tonight and
Monday with northerly flow aloft. At the surface, high pressure
offshore will shift over the area tonight and Monday. The air
mass is stable.

The low levels will be moist into Monday with dry air aloft. There
will be areas of low clouds tonight with a mix of VFR and MVFR.
There is chance of IFR ceilings during the morning hours on Monday.
Moisture will decrease late Monday. Most areas should eventually
scatter Monday but clouds will be slow to clear with light winds.

KSEA...Tough call at Sea-Tac Monday morning. Scattered to broken
cloud deck around 2000 with another layer around 4000 feet over the
terminal into the early morning hours. With light flow and plenty of
moisture in the lower layers there is a good chance a lower stratus
deck forms Monday morning below 1000 feet. Ceilings should lift back
to VFR by early afternoon with the clouds scattering out
Monday evening. Light winds through Monday. Felton


.MARINE...High pressure building in from the west will bring small
craft advisory strength northerly winds to the Coastal Waters until
the early morning hours on Monday. The 10 foot west swell over the
Coastal Waters will subside below 10 feet early Monday morning as

High pressure will shift inland Monday with offshore flow
developing. Offshore flow will continue Tuesday through Friday.
Easterly small craft advisory strength winds are possible at times
in the Strait of Juan De Fuca mainly at the west entrance and over
the Coastal Waters near gaps in the coastal terrain. Felton


.HYDROLOGY...River flooding is not expected the next 7 days.


PZ...Small Craft Advisory until 1 AM Monday for the 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.

     Small Craft Advisory for rough bar until 7 AM PST Monday
     for Grays Harbor Bar.

     Small Craft Advisory until 1 AM PST Monday for Coastal
     Waters From Point Grenville To Cape Shoalwater Out
     10 Nm.


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