Small Craft Advisory 78, NWS Seattle, WA

Area Forecast Discussion
National Weather Service Seattle WA
900 PM PDT Mon Apr 3 2017

.SYNOPSIS...Dry weather will prevail tonight and Tuesday morning as
a ridge moves across Western Washington. A frontal system will bring
high clouds tonight with a little light rain along the coast on
Tuesday afternoon. A warm front will move across the area Tuesday
night followed by a very slow moving cold front Wednesday and
Wednesday night. Wetter weather will continue Thursday through the
weekend as a series of frontal systems cross the region.

&&

.SHORT TERM...High clouds have begun moving into Western Washington
this evening. The warm front associated with the approaching system
will spread a little light rain to areas west of Puget Sound and
possibly over the Cascades Tuesday afternoon. A little light rain
will reach the interior lowlands Tuesday night. The approaching warm
front will push high temperatures on Tuesday up to near 60 in spots
over the SW interior and E of Puget Sound. On Wednesday, Western
Washington will be in the warm sector behind the warm front and
ahead of the cold front. High temperatures could be the warmest so
far of 2017, with lower 60s possible over the SW interior and the
Greater Puget Sound region.

The best chance of rain over the interior appears to be on Wednesday
and then again on Thursday. Most model POPs are in the likely
category both days. Highs on Thursday will be mostly in the mid to
upper 50s. Kam/Burke

.LONG TERM...Previous discussion...The GFS and ECMWF show A third
shortwave trough deepening into an upper level low as it moves NE
across the region Friday and Saturday. The active weather pattern
will continue Sunday and Monday when another upper level low moves E
across the area. There is still lots of time for the character and
timing of these systems to evolve, so the forecast remains more of a
broadbrush of chance and likely POPs through the period. Kam

&&

.AVIATION...An upper ridge just off the coast is due to move
onshore through Tuesday. NW flow aloft becoming westerly early
Tuesday then SW by late Tuesday. A Pacific frontal system to
approach the coast from the west through Tuesday. Low level flow
becoming offshore. Air mass stable with increasing mid and high
level moisture through Tuesday.

KSEA...Cirrus level clouds overnight tonight. Ceilings gradually
falling with mid level clouds above 070 Tuesday morning. NW wind
about 5 kt becoming NE overnight, then SE Tuesday morning. Buehner

&&

.MARINE...A strong Pacific frontal system about 700 nm offshore is
forecast to approach the coast Tuesday and then move ashore but
weaken considerably Tuesday night into Wednesday. Low level offshore
flow ahead of this system.

The next Pacific weather system is expected to approach from the
southwest Friday with a deep low weakening and moving onshore Friday
night into Saturday. Moderate onshore flow in the wake of this
system Saturday. Buehner

&&

.HYDROLOGY...River flooding is unlikely over the next 7 days.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Gale Watch Tuesday evening 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 from 3 AM to 6 PM PDT Tuesday 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.

&&

www.weather.gov/seattle

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