Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 112257

Area Forecast Discussion
National Weather Service Seattle WA
300 PM PST Sun Feb 11 2018

.SYNOPSIS...Skies will clear from the north this evening with low
level northerly flow. Monday will be sunny and Tuesday will be
mostly sunny. A weak system arriving from the northwest Tuesday
night will bring rain Wednesday. More weak systems will affect the
area through Friday. A stronger system may arrive Saturday with
colder weather possible next Sunday.


.SHORT TERM...Precipitation, which had been spotty and light over
southern areas, has now mainly ended. There is still some upslope
cloudiness around the Strait, and there is a stratocumulus field
over the area from King County south, but clouds will start to
dissipate after sunset and should be totally gone later tonight as
north winds bring a drier air mass into the region. Expect a brief
round of gusty Fraser river outflow winds in Whatcom county tonight.
Overnight lows will be mostly below freezing, 25-30.

Monday will be sunny with dry northerly flow aloft and at the
surface. Northerly winds will diminish during the day. Highs will
remain a little below normal, in the 40s.

There will be little change in the pattern Monday night. Clear skies
will allow temperatures to fall into the 25-30 range again. Notably
lighter winds will allow some freezing fog to develop in susceptible
locations. Tuesday will be mostly sunny, but the upper level ridge
will flatten as another weather system begins to move south along
the British Columbia coast. Clouds will increase late Tuesday but
any precipitation will hold off until Tuesday night. Highs Tuesday
will be in the mid 40s to near 50.

The models all bring precipitation into the area late Tuesday night
and Wednesday. Have generally increased pops to likely or better
during this period. With the increased cloud cover, minimum
temperatures should remain above freezing, so the precipitation will
be in the form of rain. The air mass will still be cool, though, and
the snow level will be around 1500 feet. By Wednesday afternoon the
rain will turn more showery as the upper level short wave trough
moves away from the area. Burke

.LONG TERM...Have generally kept low chance pops in the forecast
Thursday and Friday as there are no organized systems in the models
but all have dribs and drabs of precipitation. Temperatures will be
near normal with highs mostly 45-50 and lows mostly 35-40.

On Saturday the Euro and GFS both bring a wetter system into the
region from the northwest. This system seems likely to produce rain
over Western Washington. Behind the upper trough, heights fall below
530dm Saturday night, and don`t rebound much on Sunday. This will
give lower temperatures overall, with low snow levels on Sunday for
any residual showers. Burke


.AVIATION...Low level clouds will clear out tonight due to north
flow. The air mass is dry and stable. VFR conditions are expected.

KSEA...Skies clearing with VFR conditions. N winds to 12 kt. 33


.MARINE...N/NE winds will prevail tonight with Small Craft
Advisories over all waters. Winds will ease Monday morning.
Offshore flow will continue on Monday with high pressure along the
coast. High pressure will shift inland on Tuesday. A cold front
will cross the area Tuesday night into Wednesday. High pressure
will bring a period of lighter winds on Thursday. 33


.HYDROLOGY...River flooding is unlikely over the next seven days.


PZ...Small Craft Advisory from 6 PM this evening to 10 AM PST Monday
     for 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.

     Small Craft Advisory until 10 AM PST Monday for Admiralty Inlet-
     Central U.S. Waters Strait Of Juan De Fuca-East Entrance
     U.S. Waters Strait Of Juan De Fuca-Northern Inland Waters
     Including The San Juan Islands-Puget Sound and Hood Canal-
     West Entrance U.S. Waters Strait Of Juan De Fuca.


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