Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 241706 CCA
AFDSEW

Area Forecast Discussion...CORRECTED
National Weather Service Seattle WA
1006 AM PDT Mon Apr 24 2017

.SYNOPSIS...Showery weather will continue for much of the upcoming
week as a series of weather systems move through. There should be a
dry spell tonight and the first part of Tuesday as high pressure
aloft crosses the area. Another dry period is likely Friday and
Saturday.

&&

.SHORT TERM...
Most of the precipitation was occurring over the southern part of
the forecast area at this time. There has also been some clearing
over parts of the Olympic peninsula this morning. The latest model
guidance indicated that, with the exception of the mountains, the
northern part of the CWA will be dry this afternoon. Meanwhile, the
upper level low presently off the north coast will continue moving
south before moving inland over northwest Oregon later this
afternoon. The Low will then continue to head east this evening for
a decreasing threat of showers.

Upper level ridging will take over during the overnight period and
into Tuesday morning. As usual...the relief proves brief as a front
associated with upper level low pressure to the north makes its way
onto the coast by mid-afternoon...spreading precip eastward reaching
most locations by Tuesday evening. Shortwave disturbances in the
flow look to keep shower activity locked over the area into
Wednesday. It would be nice to point out that it looks like showers
will become more scattered in nature Wed afternoon and evening...GFS
model runs have been going back and forth between wet solutions and
dry solutions every other run while the ECMWF...as usual...favors a
wetter scenario. Clinging desperately to the hope that this active
pattern will eventually end...so have opted to side with drier GFS
solutions.

The upper low will shift eastward Thursday...ramping up precip yet
again and resulting in continued wet conditions.

Temperatures in the near term look to hover in the lower to mid 50s
as the mix of precip and clouds prove to be a pretty big hurdle to
overcome as the quest to return to 60 slogs on.  SMR/05

.LONG TERM FROM THE PREV DISCUSSION...
As the aforementioned upper low continues to move east Thursday
evening showers look to taper off. Models remain consistent in an
upper level ridge following this feature and dry conditions look to
be on tap for Friday and into Saturday morning. Models diverge here
with...shockingly...the ECMWF keeping conditions dry for the bulk of
the day Saturday while the GFS is more progressive with yet another
upper level low. Both models have some showers in for Sunday thanks
to the low from the previous sentence and also continue to
advertise a light at the end of the tunnel with an upper level ridge
over the area for the first half of next week. Would absolutely
love to bite on to this solution...but 24 hours ago models were
suggesting this ridge for the upcoming weekend. This brings forth
the question...have the models just shifted their timing...or have
they adopted a stick-and- carrot philosophy to lead forecasters to
their doom. Needless to say...will be curious as to what models will
advertise 24 hours from now. SMR

&&

.AVIATION...A low pressure system is moving into northwest Oregon
this morning. Rain with this system is falling south of Seattle. The
low will move inland this afternoon and scattered showers will push
into the area with stronger onshore flow. The mountains will be
obscured at times--especially in the south.


KSEA...Some light rain at times this morning will turn to scattered
showers later today as a weather system moves ashore over northwest
Oregon. A northerly breeze will increase this afternoon and then
switch to southerly tonight.

&&

.MARINE...A surface low is moving ashore over northwest Oregon this
morning, so the winds will back from NE to NW and increase. Another
front will arrive Tuesday afternoon and evening. Strong onshore
flow Wednesday will gradually ease through the end of the week as
high pressure builds.

&&

.CLIMATE...
So far (ending at 8 AM PDT, this morning), there has been 44.66
inches of rain at Seattle-Tacoma International Airport since October
1st, 2016. This breaks the previous October through April record of
44.52 inches set in 2015-16.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 6 PM this evening to 3 AM PDT Tuesday
     for Central U.S. Waters Strait Of Juan De Fuca-East Entrance
     U.S. Waters Strait Of Juan De Fuca.

&&

$$

www.weather.gov/seattle

An illustrated version of this forecast discussion can be seen at
www.wrh.noaa.gov/sew/gafd/latest_webafd.html



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