textproduct: Seattle/Tacoma

UPDATE

Areas of fog have developed earlier this morning over several travel corridors south and southwest of the Puget Sound, including I-5 through Chehalis, along US-101 along the Kitsap Peninsula, and US-12 through Montesano. A Dense Fog Advisory has been issued through noon today for these areas. Conditions are expected to improve throughout the morning as the fog slowly burns off, with the remainder of the forecast this morning on track as benign conditions settle over the area.

SYNOPSIS

Upper level ridge centered offshore building today and tonight. The ridge will remain in place through most of the week. Weak systems moving over the top of the ridge at times. Ridge weakens Saturday with an upper level trough approaching the coast.

SHORT TERM /TODAY THROUGH TUESDAY/

Western Washington getting off the weather roller coaster this week. Upper level ridge building offshore today with the ridge remaining in place through Tuesday. For today and Monday weak onshore flow with areas of morning clouds and sunny afternoons. Patchy fog this morning South Sound. Weak system riding by to the north Tuesday will increase the low level onshore flow for more cloud cover. Highs warming into the lower to mid 60s today and 60s all areas Monday. A little cooler with more cloud cover Tuesday, upper 50s to mid 60s. The system on Tuesday could produce a shower in the North Cascades in the afternoon.

Felton

LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/

Little change in the pattern with flat upper level ridge centered offshore and weak systems moving by to the north at times through Friday. Weak upper level trough approaching the coast Saturday will still be far enough offshore to have a dry forecast. Highs in the 60s and lower 70s Wednesday and Thursday, mid 60s to mid 70s Friday and Saturday. Lows mostly in the 40s.

AVIATION

Northerly flow aloft will persist today as an upper level trough exits the region to the southeast and an upper level ridge starts to build back into the area from the NE Pacific. There is a mix of MVFR ceilings in the eastern terminals, and a few lower ceilings/patches of mist/fog in the central and south interior. These will continue to scatter/lift through the morning and early afternoon for VFR conditions regionwide. Expect winds to increase out of the north/northwest today. They will persist at 5-10 kt into the evening hours before easing tonight. East terminals will see the direction of the wind flip to the south overnight. A weaker onshore push Monday morning will bring stratus inland. Highest likelihood for MVFR is from the Kitsap Peninsula south and westward. There is also a medium chance for patches of fog in the Kitsap/Chehalis Valley Monday morning.

KSEA...There remains a chance of ceilings dipping down to MVFR this morning through 18Z (a few lower clouds remain to the west of the terminal but at this point will likely stay over the Kitsap Peninsula). Calm winds will pick up from the north at around 18Z, holding at 5-8 kt this afternoon and evening before easing tonight and switching back to the south. Probabilities for ceilings Monday favor lower-end VFR at this time.

14/HPR

MARINE

High pressure will build back over the waters today. Another push of small-craft westerly winds is expected along the central and eastern Strait this afternoon and evening. Seas across the coastal waters have also subsided and will primarily range between 6-8 ft throughout the day.

A weak, dissipating frontal system will move across the area waters Monday into Tuesday, before high pressure builds back in its wake on Wednesday. Onshore flow will persist through the first half of the week and will result in daily pushes of westerly winds through the Strait of Juan de Fuca. Another weak frontal system looks to move into the area waters on Thursday. Seas will generally hover between 6-8 ft through the first half of the week, before slightly increasing towards 8-10 ft by late week.

14

HYDROLOGY

The daily hydrology discussion has ended until the start of the next rainy season; it will only be updated during this time as needed.

SEW WATCHES/WARNINGS/ADVISORIES

WA...Dense Fog Advisory until noon PDT today for Lower Chehalis River Valley-Lowlands of Lewis and Southern Thurston Counties-Middle Chehalis River Valley-Olympia and Southern Puget Sound.

PZ...Small Craft Advisory from 5 PM this afternoon to 5 AM PDT Monday for Central U.S. Waters Strait Of Juan De Fuca- East Entrance U.S. Waters Strait Of Juan De Fuca.