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Area Forecast Discussion (AFD)

Issued by Seattle/Tacoma, WA (SEW)

FXUS66 KSEW 221600

Area Forecast Discussion
National Weather Service Seattle WA
900 AM PDT Fri Mar 22 2019

.SYNOPSIS...A weak front will move through the area later today.
Showers will become isolated behind the front tonight and Saturday
then end Saturday evening. Another front will reach the area on
Monday. Generally dry weather is expected in the middle of next
week with weak high pressure aloft over the area. 


.SHORT TERM /TODAY THROUGH SUNDAY/...Skies are currently mostly 
sunny for a good part of the area but clouds should increase from 
the southwest today as a front approaches. The aforementioned 
front will bring a few hours of light rain this afternoon/early 
evening as it moves from southwest to northeast across the area. 
It will get a little breezy with the front for a few hours later 
today but nothing too exciting. 

Showers look pretty limited behind the front and most areas will 
be dry later tonight into Saturday morning. Some showers should
bubble up later Saturday with daytime heating and a weak upper 
trough moving into the area providing some lift. There might also
be an isolated thunderstorm in the afternoon near the coast and 
over the Southwest Interior where it will be a bit unstable.

Showers will pretty much end after Saturday evening as weak high 
pressure aloft moves over the area. Low level flow will turn 
offshore on Sunday which should help dry things further with 
clouds decreasing during the day. Highs will be slightly above 
normal the next few days. Schneider

.LONG TERM /MONDAY THROUGH THURSDAY/...A frontal system will
spread rain into the area from the southwest on Monday. Some 
showers will likely linger into Tuesday behind the front but the 
trend will be for drying. It looks like a blocking pattern will
develop Wednesday and probably continue into Thursday. Wednesday 
is looking dry for now with Western Washington in between a cutoff
upper low well to the south and the northern stream in Canada.
High pressure aloft will build into the area from the northwest on
Thursday for more dry weather although confidence is not high
about this. Schneider


.AVIATION...A cold front will spread rain inland this afternoon 
and evening to Western Washington. The flow aloft is southerly. 
Skies are mainly VFR this morning except for patchy fog in the 
south sound and river valleys. The air mass will remain moist
tonight with onshore flow and additional showers. MVFR ceilings
are likely. 33

KSEA...VFR conditions today. Rain spreading to the terminal by 00z
this afternoon. S winds at the surface increasing to 10-15kt this
afternoon. MVFR cigs likely overnight with additional showers. 33


.MARINE...Winds will increase over the waters today as a cold
front moves inland - Small Craft Advisories are in effect for all
waters. Meanwhile, seas will also build to 10-14 feet. Winds and
seas will ease on Saturday. The flow will turn offshore on 
Sunday. The next frontal system will arrive on Monday. 33


.HYDROLOGY...River flooding is not expected for the next 7 days.


PZ...Small Craft Advisory until 5 AM PDT Sunday 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 11 PM PDT this evening 
     for Grays Harbor Bar.

     Small Craft Advisory until 5 AM PDT Saturday for East Entrance 
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 6 PM this evening to 5 AM PDT Saturday 
     for Central U.S. Waters Strait Of Juan De Fuca-Northern 
     Inland Waters Including The San Juan Islands.

     Small Craft Advisory until midnight PDT tonight for Admiralty 

     Small Craft Advisory until 3 AM PDT Saturday for Puget Sound and 
     Hood Canal.