Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 271523
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
822 AM PDT Thu Jul 27 2017

.SYNOPSIS...Morning clouds and some patches of drizzle should
break up in the afternoon. Friday should see morning clouds and
afternoon sun and a little warming. The weekend will have sunny
skies and warmer temperatures and a warming trend could continue
into next week.

&&

.SHORT TERM...Clouds and marine air have pushed over most of the
lowlands this morning, and partway into the mountains. After a misty
morning the marine layer should lift and break up somewhat this
afternoon and evening. The higher elevations of the mountains are
mainly in the sun, and the north Cascades does not have much in the
way of clouds. A good part of the San Juans is also in the sunshine
this morning. For most of the lowlands, the clouds will set back up
again overnight but should break up okay on Friday. Saturday should
be sunny with just some shallow marine layer clouds, and mainly just
on the coast in the morning. Sunday could have a deeper marine layer,
but it should burn off fine with temps only falling off a touch.
500mb heights will be up around 588 dam over the weekend and 850mb
temps will be around 15c over Puget Sound. So, that should mean
more of the same sort of weather that we have been having of late.

.LONG TERM...Another weak trough should move over the north side
of the ridge on Sunday, and that should bring a bit more marine
influence and a few degrees of cooling Sunday and Monday. However,
the weather both days still looks generally sunny and slightly
warmer than normal. It looks like a more significant spell of
warmer weather will start to take shape Tuesday and Wednesday, as
high pressure centered over Nevada extends into the Pacific
Northwest. By Wednesday, highs across the Western Washington
interior lowlands should be mainly in the upper 70s and 80s.
McDonnal

&&

.AVIATION...An upper trough over the area will weaken today
and tonight with southwest flow aloft becoming west. At the
surface, high pressure will be offshore with lower pressure
inland. The air mass is table.

MVFR and IFR low clouds and patchy fog currently cover most of
Western Washington. These clouds will start to lift late this
morning and will eventually break up most areas in the afternoon.
MVFR low clouds will redevelop tonight for most areas.

KSEA...IFR low clouds should lift to MVFR late this morning and
then scatter in the afternoon. MVFR low clouds are expected to
redevelop late tonight. Southerly wind 4-8 knots will become
westerly in the afternoon and then northerly this evening.
Schneider

&&

.MARINE...Onshore flow will continue for the next several days
with high pressure offshore and lower pressure inland. Expect
at least small craft advisory west winds each night in the
Central and Eastern Strait of Juan De Fuca with marginal gales
possible as well. Schneider

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 5 AM PDT Friday for Central U.S.
     Waters Strait Of Juan De Fuca-East Entrance U.S. Waters
     Strait Of Juan De Fuca.

     Small Craft Advisory from 5 PM this afternoon to 5 AM PDT Friday
     for Northern Inland Waters Including The San Juan Islands.

&&

$$

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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