Brier Weather Station
Latitude N 47° 46' 49" Longitude W 122° 16' 48" Elevation 341 ft
587
FXUS66 KSEW 191624
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
930 AM PDT Thu Oct 19 2017
.SYNOPSIS...Rain will continue over mainly southern sections today,
with showers elsewhere. The snow level will fall to 4000 feet or so
by Friday with snow accumulation likely in the mountains. A strong
front will affect Western Washington on Saturday with heavy rain and
some wind. Drier weather is forecast to develop early next week as a
ridge of high pressure builds over the region.
&&
.SHORT TERM...Radar shows a rain band over the southeast portion of
the CWA, with showers northwest of that band. Model forecasts have
this band slowly moving southeast, while showers in the northwest
portion become enhanced in the afternoon. Pops are high, QPF is
moderate today. Winds have eased for the time being, but breezy
conditions are likely at times through Friday. A lull in shower
activity is expected between systems tonight through Friday night.
Models remain in agreement that the next strong system will affect
the area over the weekend. A warm front will spread rain into
northwest Oregon late Friday night. The warm front will move north
into Western Washington on Saturday with increasing rain and breezy
to locally windy conditions. The southeast gradient will be tight
but the direction is not favorable for high wind in most spots.
However, the coast and north interior would be the spots to watch
for the highest wind gusts. Elsewhere it will be windy Saturday
night and some advisory level wind gusts possible. Statements to
address specifics on the wind and rain this weekend are likely to be
issued today as new model data arrives. Mercer/Burke
.LONG TERM... Previous discussion...Rainfall will gradually ease
Sunday night and Monday. River flooding could still be occurring on
some rivers. Long range models show a drying trend Monday and
Tuesday. The ECWMF differs from the GFS and brings some light rain
through on Wednesday. Kept low pops in the forecast. The overall
pattern looks to shift toward a more benign pattern with mostly dry
weather and mild temperatures. Mercer
&&
.AVIATION...A frontal system will continue to slowly sag
southeast through the area today, with low level onshore flow
behind the front. The air mass is moist and it will become
unstable this afternoon, especially at the coast. Southwest flow
aloft will continue.
There is a wide range of conditions across Western Washington this
morning, but much of the area has MVFR ceilings 015-025 with local
ceilings AOB OVC010. On the large scale, there will be little
change in conditions through tonight.
KSEA...South wind 7-13 kt. MVFR ceilings should be the prevailing
conditions through tonight, with breaks at times. McDonnal
&&
.MARINE...A front will continue to move slowly inland today.
Onshore flow will develop behind the front and continue into
Friday. Small craft advisory strength winds will gradually ease
today although they could linger in spots into tonight and Friday.
Another vigorous frontal system will move through the area
Saturday and Sunday. Onshore flow behind the front will ease and
eventually turn weakly offshore later Monday. 20-24 foot west
swell will affect the Coastal Waters later today through Friday
morning before easing below 20 feet later Friday. McDonnal
&&
.HYDROLOGY...The South Fork Nooksack River just touched flood stage
at Saxon Bridge overnight, but it has now fallen well below flood
stage. Other rivers did not reach flood stage and are now mostly
falling. With just showers in the forecast over the north today and
Friday, all the warnings and watches from the rain yesterday and
last night have ended.
Another rain event is scheduled for Saturday and Saturday night.
Models show heavy rain beginning in Oregon Saturday morning, then
spreading north Saturday afternoon and evening. Will probably issue
a widespread flood watch this afternoon for minor flooding on some
area rivers. There is also a concern for mudslides in the recent
burn scar near Crystal Mountain, so may also issue a flash flood
watch for that area this afternoon. Burke
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...High Surf Advisory until 6 AM PDT Friday for Central Coast-North
Coast.
PZ...Small Craft Advisory until 6 PM PDT Friday 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 6 PM PDT Friday for
Grays Harbor Bar.
Small Craft Advisory until noon PDT today 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.
Small Craft Advisory for hazardous seas until 6 PM PDT Friday
for West Entrance U.S. Waters Strait Of Juan De Fuca.
&&
$$
www.weather.gov/seattle
You can see an illustrated version of this discussion at
www.wrh.noaa.gov/sew/gafd/latest_webafd.html
NWS SEW Office Area Forecast Discussion