Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS66 KSEW 161632
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
832 AM PST Tue Jan 16 2018

.SYNOPSIS...Showers will continue across Western Washington today
with moist southwest flow over the region. A strong frontal system
will bring rain Wednesday and Wednesday night with showers late in
the week. It will also generate large waves which may impact the
coast. Unsettled weather will continue into this weekend with a
trough over the region.

&&

.SHORT TERM...Showers will decrease across the area today, likely
ending entirely this evening in the wake of a front that brought
rain last night. Highs will be around 10 degrees cooler today but
still warmer than normal and relatively mild.

A frontal system will bring rain and wind Wednesday and Wednesday
night. A warm front will lift north through the area Wednesday
morning. A trailing cold front will bring another round of steady
rain later Wednesday afternoon and evening. Showers will linger
over the region into Thursday with moist southwest flow aloft.

As mentioned above, the Wednesday system will bring some breezy
to windy conditions. The strongest winds will be at the coast and
Northwest Interior. Winds in these areas are expected to remain
below advisory levels but a few spots in the Northwest Interior
might get close.

Snow levels will be fairly high with the heaviest precipitation
later Wednesday - above pass levels and probably even above the
ski areas on the volcanoes. East winds in the passes Wednesday
might complicate things however. Snow levels will drop to
3000-3500 feet Thursday but it should be showery by then. Advisory
amounts are possible but heavy snow in the mountains is not
expected at this time. Schneider

.LONG TERM...Previous discussion...The forecast remains unsettled
through the weekend with upper level troughing over the West.
Showers are likely through the period. Temperatures are trending
close to normal. We may see a break in the action early next week
with weak upper level ridging. No major changes from the previous
forecast. 33

&&

.AVIATION...Moderate southerly flow aloft this morning will turn
westerly this afternoon and tonight. At the surface, moderate
southeasterly winds will continue today and ease tonight. The air
mass is moist and slightly unstable. Any precip activity is expected
to be of a showery nature.

Generally low-end VFR to MVFR cigs this morning...although there are
a few isolated locations seeing IFR. Expecting improvement to more
widespread low-end VFR conditions by late this morning. MVFR cigs
will still be possible in showers.

KSEA...Discussion above applies. Southerly wind 10-15 kt today.
CHB/SMR

&&

.MARINE...Winds over the waters are gradually subsiding...with the
last gales subsiding in the East Strait. Small craft winds still
expected at least into late this afternoon...possibly bleeding into
the early evening.

A deep low will move northeast well off the coast Wednesday and
Thursday. The resulting gradient will bring gales to most waters,
and a gale watch is in effect. Will wait until the afternoon
forecast package to start filling in other waters with potential
small craft advisories. More fronts later in the week will keep the
weather vigorous.

Strong southwest winds well off the coast will generate large swells
that will reach the Washington coast Thursday. Models have been
consistent in bringing westerly swells of 25 ft or more to the
coast, with even larger swells offshore. These have the potential to
be the highest seas in at least several years. Will likely get the
ball rolling on headlines for the afternoon package for Central
Coast...due to erosion concerns at Ocean Shores. While North Coast
looks to be affected as well...will likely adhere to more standard
WWA time frames. CHB/SMR

&&

.HYDROLOGY...A brief period of heavy rain is possible in the
Skokomish Basin on Wednesday evening. This will cause the river to
rise on Wednesday night and Thursday morning. Current rainfall
forecasts support bringing the Skokomish to within a foot of flood
stage. This will bear watching, as forecast rainfall amounts are
prone to change.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Gale Watch from late tonight through late Wednesday night 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-East Entrance U.S.
     Waters Strait Of Juan De Fuca-Northern Inland Waters
     Including The San Juan Islands.

     Small Craft Advisory until 3 AM PST Wednesday 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.

     Small Craft Advisory for rough bar until 4 AM PST Wednesday for
     Grays Harbor Bar.

     Small Craft Advisory until 4 PM PST this afternoon for Admiralty
     Inlet-East Entrance U.S. Waters Strait Of Juan De Fuca-
     Northern Inland Waters Including The San Juan Islands-Puget
     Sound and Hood Canal.

&&

$$

www.weather.gov/seattle


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.