Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 240948
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
248 AM PDT Tue Oct 24 2017

.SYNOPSIS...High pressure aloft will provide dry weather today.
A weak front will move through the area Wednesday with some light
rain. Dry weather will return Thursday and should prevail through
the weekend. Areas of fog are likely late in the week.

&&

.SHORT TERM...An upper ridge over the area will produce a dry and
sunny day today after some patchy morning fog. Highs will be a few
degrees above normal.

A weakening front will bring a little rain Wednesday. Precipitation
chances will be highest near the coast with lesser chances inland
as the front falls apart. Highs will cool to near normal.

A few showers will linger into Wednesday evening as the front
shifts inland and dissipates. High pressure aloft will rebuild
over the area from the west Thursday for another dry day.
Schneider

.LONG TERM...A strong upper ridge will be the main weather feature
Friday through Monday for dry weather. Night and morning fog is
possible each day in this pattern.

Recent model runs show a weak upper trough bringing a few showers
Sunday. The forecast is dry for now but a chance of showers might
need to be introduced to the forecast if models remain consistent
with this feature. Schneider

&&

.AVIATION...A strong upper level ridge will remain over the PacNW
through 06Z. The air mass will be dry and stable except for patchy
morning fog or low stratus through about 19Z. A weak cold front
moving down the B.C. coast will move S across W WA on Wednesday.

KSEA...Clear skies today. It is looking less likely that patchy
morning fog or low stratus will reach the terminal this morning.
However, I will still keep a FEW006 group in the KSEA TAF after
12Z to address the remote possibility. Surface winds will be
northerly up to 7 kt. KAM

&&

.MARINE...A surface ridge centered over the Pacific Northwest
will maintain weak N to NE offshore flow through this evening. A
weak cold front will move south across the area on Wednesday.
Ahead of the front early Wednesday, W flow in the Central strait
could reach SCA levels. NW flow behind the front Wednesday
afternoon will reach SCA levels over the coastal waters. There
could be some borderline SCA NW winds near Point Roberts behind
the front on Wednesday.

Northerly offshore flow will prevail Thursday and Friday as a
surface ridge builds over southern British Columbia and a
thermally induced surface trough forms along the Oregon coast.
Kam

&&

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

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.

&&

$$

www.weather.gov/seattle

You can see an illustrated version of this discussion at
www.wrh.noaa.gov/sew/gafd/latest_webafd.html


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