Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 241555

Area Forecast Discussion
National Weather Service Seattle WA
900 AM PDT Mon Oct 24 2016

.SYNOPSIS...Weak fronts will bring occasional light rain to Western
Washington through Tuesday. A wetter system will move into the area
on Wednesday and linger into Thursday. Drier weather is possible
late in the week.


.SHORT TERM...A large closed upper trough and vertically aligned
968mb surface low located about 350 miles off the Washington coast
will continue moving northward today. Radar shows the associated
frontal band just now reaching the coast with light rain reported at
Hoquiam this past hour. Lightning detection is picking up strikes
well offshore near the low center. Thunderstorms are not expected
over land today, just some light rain slowly spreading inland this
morning. Models show the precipitation band breaking up and becoming
more showery and light this afternoon and tonight. The southerly
flow pattern will favor training of showers along the terrain east
and west of Puget Sound but there is some chance of measurable rain
just about anywhere. Little change in the pattern Tuesday with light

The 968mb low offshore has a large gradient field with offshore
winds this morning across Western Washington. As the low moves
further north tonight and Tuesday, stronger southeasterly gradient
develops at the coast and from Admiralty inlet northward. Windy
conditions will develop in these areas and there is a chance of a
few spots hitting gusts to around 45 mph which is low end wind
advisory criteria. Will take a closer look at the all the latest
meso models before deciding on any possible advisories with the
afternoon forecast package.

A warm front will lift across the area on Wednesday with steady
light rain rain much of the day. Models show roughly .25 to .75
inches across the lowlands and up to 2 inches along south facing
mountain slopes, especially the olympics. Will need to watch the
Skokomish river but the crest estimator gives a peak of about 16
feet by Wednesday night/Thursday which is a foot below flood stage.
No flood outlook needed at this time. Mercer

.LONG TERM...No update from previous discussion...Models seem to
agree that Friday might see a brief respite in the rainfall as a
pretty progressive ridge pushes through the area. While both models
then bring rain back into the forecast...the GFS suggests a scenario
similar to what has been observed this past weekend and is expected
for the early portion of the week...where there will be some
lingering showers but also the potential for some breaks. The ECMWF
however paints a far gloomier and soggier picture. Once again...will
guide forecast toward the more optimistic GFS solution to provide a
glimmer of hope.  SMR


.AVIATION...A front will move onshore today with southerly flow
aloft. Moist southerly flow aloft will continue tonight. A deep
surface low - around 970 mb - will track north around 130W today
and tonight. This will maintain drier easterly low level with
moisture at mid and upper levels.

KSEA...Mid and high clouds today and tonight. East to northeast
wind 4-8 knots will become south 5-10 knots this afternoon.


.MARINE...A strong 970 mb low will slowly move northward about 300
miles west of the Washington coast this afternoon and tonight
bringing gales to the coastal waters. As E-SE gradients peak later
tonight, gales are possible near the East Entrance and Northern
Inland Waters. The low will continue to move north on Tuesday
toward Haida Gwaii.

Next surface low, a 992 mb low, will track northward inside 130W,
weakening as it makes landfall on northern Vancouver Island
Wednesday night.

Low level flow will turn offshore on Thursday and remain
offshore on Friday. Felton/Schneider


PZ...Gale Warning until noon PDT Tuesday for Coastal Waters From Cape
     Flattery To James Island 10 To 60 Nm-Coastal Waters From
     James Island To Point Grenville 10 To 60 Nm-Coastal Waters
     From Point Grenville To Cape Shoalwater 10 To 60 Nm.

     Small Craft Advisory for rough bar from 11 PM this evening to 7
     AM PDT Tuesday for Grays Harbor Bar.

     Gale Warning from 3 PM this afternoon to noon PDT Tuesday for
     Coastal Waters From Cape Flattery To James Island Out 10 Nm-
     Coastal Waters From James Island To Point Grenville Out 10
     Nm-Coastal Waters From Point Grenville To Cape Shoalwater
     Out 10 Nm.

     Gale Watch from this evening through Tuesday morning for Central
     U.S. Waters Strait Of Juan De Fuca-East Entrance U.S.
     Waters Strait Of Juan De Fuca-Northern Inland Waters
     Including The San Juan Islands.

     Small Craft Advisory until 1 PM PDT this afternoon for Central
     U.S. Waters Strait Of Juan De Fuca-East Entrance U.S.
     Waters Strait Of Juan De Fuca.

     Gale Warning from 6 PM this evening to noon PDT Tuesday for West
     Entrance U.S. Waters Strait Of Juan De Fuca.



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