textproduct: Seattle/Tacoma

UPDATE

Latest radar imagery shows light to moderate rain associated with the cold front has reached the coast this morning. Expect rain to continue today as the front continues to push eastward. Isolated thunderstorms remain possible (10-20% chance) today across the region. Otherwise, no major updates to the forecast this morning. 29

SYNOPSIS

Showers and mountain snow continues today under onshore flow. Drier weather is in store moving toward the weekend as high pressure shifts inland. A trough will bring wetter weather early next week.

SHORT TERM /TODAY THROUGH FRIDAY/

Showers will increase late this morning as a quick- moving cold front slides inland. We'll then see showers with a convergence zone aimed over the King/Snohomish line this afternoon and evening. Up in the mountains, snow levels will lower to around 2500 ft today with snow in the Cascades and passes. Heaviest snow amounts will be over the north Cascades and central Cascades with Stevens Pass getting showers from the convergence zone - a Winter Weather Advisory is in effect. The air mass is slightly unstable and there's a chance of thunderstorms too. Expect highs around 50 today with cooler overnight lows in the 30s.

A weak front will clip area on Thursday for showers mainly on the coast, Olympics and north Cascades during the morning. Otherwise, we'll see drier conditions moving toward the afternoon and evening as high pressure shifts inland and the flow turns offshore.

High pressure and offshore flow will lead to dry and slightly warmer conditions on Friday. Temperatures will reach the mid to upper 50s with lower 60s possible in the interior. 33

LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/

High pressure continues into Saturday for one more dry and mild day. An offshore trough will push the ridge inland on Sunday with a chance of rain and slightly cooler conditions over western WA. Rain will increase on Monday as the trough eventually shifts inland. We may see a brief break on Tuesday then more rain headed our way by midweek. 33

AVIATION

Southwest flow aloft will continue as an upper level trough axis approaches the region and moves onshore later today. The air mass is moist and will become somewhat unstable with increasing showers and isolated thunderstorms (the thunder probability remains at 20% for today). Mainly VFR ceilings early will lower to MVFR at times in some of the heavier showers. Reduced visibilities at times are likely with the heavier showers. Increasing low level onshore flow will lead to gusty west to southwest surface winds this afternoon. A convergence zone is expected to develop later this afternoon into this evening over Snohomish and north King counties. The breezy southwest winds into Thur

KSEA...VFR ceilings early will lower to MVFR at times after 17Z in increasing showers. Ceilings are expected to improve again after 00Z to mainly VFR. First line of rain is expected to pass through 18- 20Z. Reduced visibilities are possible with this line. Convergence zone activity later today is expected to remain mainly north of the terminal. Surface winds southerly 8 to 12 knots will become southwesterly 15 to 25 knots this afternoon then ease this evening. Low confidence in winds briefly becoming erratic between 22Z and 03Z as a convergence zone develops north of the airport.

27/HPR

MARINE

An upper level trough axis moving onshore later today will induce an increase in onshore flow late this morning into this evening. Breezy winds will pick up out of the west as the cold front passes through Winds will ease tonight into Thursday as a broad surface ridge builds across the coastal and interior waters. The ridge will gradually shift inland on Friday leading to a period of northerly flow. A weak trough and associated frontal system will reach the waters on Sunday, but is not presently expected to produce much in the way of impacts.

Hazardous coastal seas will gradually subside below 10 feet later today and remain in the 5 to 8 foot range heading into the weekend.

27/HPR

HYDROLOGY

No river flooding over the next 7 days.

SEW WATCHES/WARNINGS/ADVISORIES

WA...Winter Weather Advisory until 5 AM PDT Thursday for Cascades of Snohomish and Northern King Counties-Cascades of Whatcom and Skagit Counties.

PZ...Small Craft Advisory until 11 AM PDT this morning for Grays Harbor Bar.

Small Craft Advisory until 11 PM PDT this 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-West Entrance U.S. Waters Strait Of Juan De Fuca.

Gale Warning until 8 PM PDT this evening for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory until 11 PM PDT this evening for Northern Inland Waters Including The San Juan Islands.

Small Craft Advisory until 6 PM PDT this evening for Admiralty Inlet.

Small Craft Advisory until 7 PM PDT this evening for Puget Sound and Hood Canal.