Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 261643
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
945 AM PDT MON SEP 26 2016

.SYNOPSIS...A strong upper ridge will move across the area today
giving a warm and sunny day. A weak cold front will bring a chance
of light precipitation tonight and Tuesday morning to northern
areas. Days will be partly to mostly sunny Tuesday afternoon through
Thursday with dry southwest flow aloft. An upper level trough will
bring cool showery weather Friday through the weekend.

&&

.SHORT TERM...Aside from some valley fog, Western Washington is
sunny except for the far northwest corner. The fog will dissipate by
noon or so and skies will remain sunny. Highs today will be in the
70s, with some low 80s in the southwest interior. The record high in
Seattle today is 78 and the record at Olympia is 81. Highs will
be near both of these records today.

A weak front currently to the northwest will swing through the area
tonight, bringing a slight chance of rain to mainly northern areas.
Tuesday will begin cloudy but north winds will develop in the wake
of the weak front, and these winds should clear the area from north
to south in the afternoon. Highs Tuesday will be about ten degrees
lower than today, mostly 60s with some low 70s in the southwest
interior.

Not much going on Tuesday night and Wednesday. Cold upper level
trough digging south well offshore. Surface gradients remain
northwesterly with dry southwesterly flow aloft. Wednesday looks
to be mostly sunny with highs once again in the 60s and lower 70s.
With the lack of cloud cover and light surface gradients Tuesday
night will be a little chilly with the colder locations dropping
into the upper 30s. Burke/Felton

.LONG TERM...Previous discussion...extended models starting to show
more consistency in their solutions for the upper level trough. 00z
runs have the trough continuing to dig south offshore on Thursday for
another dry day. The trough moves east on Friday and into Western
Washington over the weekend resulting in cool and showery weather.
Highs next weekend will be in the lower 60s at best. The air mass
will cool considerably late in the week with the snow levels near
5000 feet for the weekend. This means Paradise on Mount Rainier
as well as the higher passes like the North Cascades highway could
see a little snow. Outside of the forecast window the models are
also consistent in showing very fall like weather after the
weekend with a series of fronts moving into the area. Felton

&&

.AVIATION...A strong upper ridge will shift inland later today and
tonight. A weak front will clip Western Washington tonight. The main
affect will to increase the low level onshore flow later today and
tonight. The air is dry and stable, there will be some cirrus and a
few patches of fog in the sheltered valleys until 10 am pdt. Low
level moisture increases tonight with Widespread MVFR cigs
developing at the coast first in the evening and inland terminals
after midnight tonight or early Tuesday morning.

KSEA...Some cirrus at times, a northwest breeze. Mid and high clouds
increase later today as a weak front clips the area. Onshore flow
will bring MVFR cigs into Puget Sound and the KSEA terminal after
10z tonight/Tuesday morning. This should quickly burn off by 18z.

&&

.MARINE...Onshore flow will pick up along the coast and in the
Strait later this afternoon as high pressure shifts inland. A weak
front moves through Western WA this evening. This could result in
near-gale force westerlies over the central and eastern portion of
the Strait of Juan de Fuca. Kept winds limited to 30 kt tonight with
models suggesting a slightly weaker push. Onshore westerly flow will
turn more northerly and decrease Tuesday.

&&

.SEW Watches/Warnings/Advisories...
WA...None.
PZ...Small craft advisory central and Eastern Strait through late
     tonight.
     Small craft advisory for Admiralty inlet this evening through
     late tonight.

&&

$$

www.weather.gov/seattle

You can see an illustrated version of this discussion at
www.weather.gov/seattle/gafd/latest_webafd.html



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