Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 151753

Area Forecast Discussion
National Weather Service Seattle WA
953 AM PST Thu Nov 15 2018

.UPDATE...Quick update this morning to increase POPs
over the San Juans and decrease POPs across west central WA through
mid-day. Otherwise the forecast is on track and no significant
changes are needed at this time. -Wolcott-


.SYNOPSIS...Today will be mostly dry with sun breaks. A weak weather
system will affect mainly northern Washington and the mountains
tonight and Friday morning. A sharp upper level ridge will give dry
conditions and patchy night and morning fog this weekend. A front
may approach the region early next week with a chance of rain.


.SHORT TERM...Showers from the weak weather system yesterday have
now entirely ended. Today will be mostly in between weather systems,
with some sun breaks or partly sunny conditions. Rain from the next
weak weather system will begin to develop in the afternoon in the
far north. Highs today will be in the low to mid 50s.

This weather system will move from north to south tonight and
Friday. It looks strong enough for likely or better pops over the
north and in the mountains, but it appears to lose punch as it moves
south. There is a wide swath of territory over the southern half of
the state with only chance pops. The system will be dissipating as
it exits to the southeast Friday afternoon, and Friday night should
be dry. Skies will clear from north to south Friday night. Highs on
Friday will be in the low to mid 50s, but overnight lows will fall
into the 30s in many places, perhaps touching the freezing mark in
the far north.

As an upper level ridge sharpens offshore, Saturday will be sunny
except for some morning fog. Highs will be only in the low 50s in
cool northerly flow. Saturday night will be cool, with widespread
lows below freezing away from the water and the urban core. Near the
water and in the cities, the lows will still be in the low to mid
30s. Burke

.LONG TERM...The upper level ridge will move slowly over Washington
on Sunday, and its effects will still be felt on Monday. Sunday will
be mostly sunny with patchy fog, with highs not quite 50. Sunday
night will be another cool one, with lows in the 30s. Have not
changed the extended forecast much, which is mostly dry on Monday
and has chance pops Tuesday and Wednesday. The recent trend in
models is toward drier conditions, with the Euro waiting until
Wednesday to bring the next system, and the GFS waiting all the way
until next Friday. Temperatures are likely to be near normal through
the period. Burke


.AVIATION...The air mass across Western WA is moist and stable.
Showers from a weak weather system will mainly affect areas near the
Canadian border today, then spread south tonight. The flow aloft is
westerly. Ceilings are a mixed bag this morning with pockets of MVFR
to IFR. We should see brief improvement this afternoon, then a
return of MVFR conditions tonight. Low clouds will linger into
Friday morning then eventually scour out Friday afternoon and
evening as offshore flow increases. 33

KSEA...Ceilings near 3000 ft this morning with some improvement this
afternoon. MVFR cigs will return this evening with -RA in the
vicinity. S winds to 10 kt at the surface. 33


.MARINE...A Small Craft Advisory for Hazardous Seas is in effect
today for the Coastal Waters and West Entrance as seas will build to
10 ft. Seas will subside late tonight. Meanwhile, south winds will
also increase over the Northern Inland Water as a frontal systems
clips the region. The Strait of Juan de Fuca will see a brief
westerly push tonight - Small Craft Advisories are in effect. The
flow will turn offshore on Friday and persist through the weekend
with high pressure building east of the Cascades. 33


.HYDROLOGY...River flooding is unlikely through the next 7 days.


PZ...Small Craft Advisory for hazardous seas until 10 PM PST this
     evening 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-
     West Entrance U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 7 PM this evening to 4 AM PST Friday
     for Central U.S. Waters Strait Of Juan De Fuca-East
     Entrance U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory until 4 AM PST Friday for Northern Inland
     Waters Including The San Juan Islands.


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