000 
fxus66 ksew 151720 
afdsew 


Area forecast discussion 
National Weather Service Seattle Washington 
920 am PST Sat Dec 15 2018 


Update...the Skokomish River fell below flood stage but is 
expected to rise back above flood stage Sunday evening. The 
warning was replaced with a Flood Watch for Mason County starting 
Sunday afternoon. An update is made to the hydrology section 
below. Otherwise, the remainder of the discussion follows. 


From the 821 am PST discussion: other than some isolated showers 
over the coastal waters, area radars show drying conditions across 
the region. Expect a relatively tranquil day today between 
weather systems. Clouds will thicken tonight and the next frontal 
system offshore will spread some rain and breezy conditions into 
the area on Sunday. 


Morning updates to the aviation, marine, and hydrology sections 
follow below. The remainder of the forecast is in good shape, and 
the previous forecast discussion follows. Albrecht 


&& 


Synopsis...a Little Break between systems today before the 
active weather pattern resumes on Sunday and continues into the 
middle part of next week. The systems from Monday through 
Thursday of next week have the potential to bring locally heavy 
rainfall and windy conditions at times. 


&& 


Short term /today through Monday/...satellite imagery shows the 
cold front that brought the windy conditions to the area late 
Friday afternoon into the evening hours is well east of the area 
early this morning. Doppler radar has widely scattered showers 
over the area with the most organized grouping of showers over 
Lewis County. Temperatures at 4 am/12z were in the upper 30s and 
lower 40s with none of the stations reporting winds above 15 mph. 


A Little Break in the action today as western Washington will be 
in between weather systems. The next front to reach the area is 
currently back near 136w. Shower activity will be minimal today 
with a little bit of warm advection ahead of the next system. 
Plenty of cloud around with high temperatures in the lower 50s for 
the most part. 


Eastward movement of the front slowing down tonight with a cool 
large and deep upper level trough behind the front digging south 
out between 140-145w. Rain out ahead of the front spreading over 
the area overnight into early Sunday morning. Lows will be in the 
40s. 


Front only to the coast by 00z Monday making for a wet day on 
Sunday for the entire area. Snow levels will rise to 5000-6000 
feet. Parent surface low associated with the front way north of 
the area so winds with the front will be way less than the Friday 
evening system. Highs on Sunday in the lower to mid 50s. Sunday 
will be the beginning of a wet few days for western Washington. 


Front moving through the area Sunday night with rain out ahead of 
the next system spreading over the area Monday afternoon. 


Long term /Monday night through Thursday/...extended models in 
good agreement with an atmospheric river scenario setting up over 
the eastern Pacific. The models are having a hard time deciding 
where the river will be aimed at in the middle of the week. 00z 
models push the river down into Oregon on Tuesday with the 
heaviest precipitation with the next impulse going into British 
Columbia on Thursday and the last front associated with the event 
moving through western Washington late Thursday. With the models 
not showing much run to run consistency will stay with the 
broadbrush rain at times forecast through the extended period. 
Felton 


&& 


Aviation...a weak upper ridge over the area will shift inland 
today. A strong frontal system will reach the area tonight. 
Westerly flow aloft will increase and become southwesterly today 
and then southerly tonight. At the surface, easterly gradients 
will increase today and tonight as the frontal system approaches. 
The air mass is stable with mid and high level moisture. 


Ceilings mostly around 10000 feet this morning with some 5000 
foot ceilings closer to the coast. The trend will be for gradual 
lowering ceilings this afternoon and evening as the front nears 
and rain develops. Low clouds should become widespread later 
tonight but easterly winds ahead of the front will likely keep 
things VFR for the interior. 


Ksea...ceilings around 10k feet today, lowering to 5000-6000 feet 
this evening as rain develops. Southerly wind 5-10 knots will 
become more easterly this afternoon and evening. Schneider 


&& 


Marine...a strong frontal system will bring another round of 
gale force southerly winds to most waters later today through 
Sunday morning. There will be a relative lull in between fronts 
later Sunday through Monday morning. A second strong frontal 
system will bring more gales later Monday and Monday night. 
Moderate onshore flow behind the second front will ease later 
Tuesday and Tuesday night. A third frontal system will approach 
from the west on Wednesday. 


The latest wave model shows 20-22 foot west swell reaching the 
coast late Sunday afternoon and Sunday night. There could be 
another brief period of west swell around 20 feet on Wednesday. 
Schneider 


&& 


Hydrology...the Skokomish River is below flood stage but rain on 
Sunday will drive the river back above flood stage. The Flood 
Warning for the Skokomish River at Potlatch has been replaced with 
a Flood Watch for Mason County starting Sunday afternoon. 


The weather pattern will remain active through next week. The 
frontal system that affects the area Monday night and Tuesday night 
is wet with high snow levels, but the rain becomes lighter Tuesday 
night and Wednesday and there is a break Wednesday night. Other 
fronts arrive around Thursday night and again next weekend--but 
those look progressive and not especially warm. We will have to keep 
an eye on rainfall amounts and snow levels and see if the models 
change much over the next few cycles. 


&& 


Sew watches/warnings/advisories... 
Washington...Flood Watch Sunday afternoon through Wednesday morning for 
Mason County. 


Pz...Small Craft Advisory until 10 am PST this morning 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. 


Gale Warning until 10 am PST 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 4 PM PST Sunday for 
Grays Harbor bar. 


Small Craft Advisory until 10 PM PST this evening for East 
Entrance U.S. Waters Strait of Juan de Fuca-northern inland 
waters including the San Juan Islands. 


Gale Warning from 10 PM this evening to 4 PM PST Sunday for East 
Entrance U.S. Waters Strait of Juan de Fuca-northern inland 
waters including the San Juan Islands. 


Small Craft Advisory until 4 am PST Sunday for Admiralty Inlet- 
central U.S. Waters Strait of Juan de Fuca-West Entrance 
U.S. Waters Strait of Juan de Fuca. 


Small Craft Advisory from 4 PM this afternoon to 4 PM PST Sunday 
for Puget Sound and Hood Canal. 






National Weather Service Glossary of Abbreviations
Back to forecast page
Non-Expanded Version (with abbreviations)

Units: English | Metric

Find the Weather for any City, State or Zipcode, or Country:

U.S. State List | Severe Weather | Tropical Storms | Ski Conditions
United States | Canada | Central America | South America | Asia | Europe | Australia | Africa | Islands

Weather Underground

© Copyright 2018
The Weather Company, LLC