textproduct: Seattle/Tacoma

SYNOPSIS

Upper level ridge and thermally induced surface trough east of the Cascades this morning. Light low level onshore flow today will increase tonight. Clouds out ahead of the first system in a couple of weeks spreading over the area Thursday. System moving through Friday with a cool upper level low dropping down over Western Washington Friday night and Saturday. Unsettled weather continuing into the first part of next week.

SHORT TERM /TODAY THROUGH FRIDAY/

Satellite imagery shows high clouds over portions of the area this morning with low stratus right along the coastline near Grays Harbor. Temperatures at 3 am/10z were in the mid 50s to lower 60s except in the Seattle metro area where temperatures were in the upper 60s.

Upper level ridge axis moved into Eastern Washington last night. West southwesterly flow aloft with high clouds at times moving through the area. Thermally induced surface trough east of the Cascades as well. Light onshore surface gradients across Western Washington early this morning will slowly increase during the day. With the cooling aloft and weak marine push in the lower levels high temperatures around 5 degrees cooler than Tuesday over the interior, in the mid 70s to mid 80s. More cooling on the coast with stronger onshore flow. Highs there in the mid 60s. Air mass becoming somewhat unstable this afternoon. Could see some picturesque build ups over the Cascades by late afternoon. Any shower activity associated with the build ups will be east of the crest.

Low level onshore flow increasing tonight with gale force winds in the Central and Eastern Strait of Juan de Fuca and breezy southwesterly wind in the south Puget Sound and Hood Canal. Stratus developing along the coast spreading inland early Thursday morning with the marine layer getting east of Puget Sound around sunrise. Lows in the 50s.

Onshore flow continuing Thursday with the marine layer retreating back to the coast in the afternoon. High clouds ahead of the next weather system spreading over the area in the afternoon making for a cloudy to mostly cloudy day. Rain out ahead of the front could reach the coast by mid afternoon. Highs only in the 60s.

Rain ahead of the approaching frontal system spreading over all of Western Washington Thursday evening with rain continuing through the early morning hours. Lows in the 50s.

Front reaching the coast Friday morning moving through the interior midday/early afternoon and into Eastern Washington by late afternoon. Rain changing to showers behind the front. Post frontal air mass unstable with a 20-30 percent chance of thunderstorms. Convergence zone forming over Snohomish county in the afternoon. Not much change in temperatures during the day with highs in the mid 50s to lower 60s. The record low maximum temperature for Seattle is 62 degrees. The forecast high is 63. Felton

LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/

Cool upper level low dropping out of the Gulf of Alaska arriving late Friday night and Saturday morning. Convergence zone could move south over the Seattle area Friday night. Upper level low will keep showers in the forecast through Saturday. High temperatures will be similar to Friday, in the mid 50s to mid 60s. Lows Friday night in the mid 40s to lower 50s.

Upper level low moving east of the area Saturday night with wrap around moisture keeping a chance of showers in the forecast. Lows again in the mid 40s to lower 50s.

North northwesterly flow aloft Sunday with an upper level ridge building well offshore and the upper level low east of the area. A couple of weak troughs embedded in the flow aloft moving through the first part of next week. Will have to leave a chance of showers in the forecast for these features. Highs will remain below normal, in the 60s with lows in the mid 40s to lower 50s.

Seattle currently sitting at the 4th warmest June on record through the 23rd. The cool weather to end the month will drop June 2026 down the list. Even with the cooler last few days Seattle still looking at ending up somewhere between the 7th and 10th warmest June on record. Felton

AVIATION

VFR conditions early this morning with some scattered mid to high clouds present. Models continue to show a medium chance (30-50%) for MVFR to IFR at HQM through 17Z, though high clouds are making it hard to see how the marine stratus is evolving. A stronger push of marine air will occur Wednesday evening, with models showing MVFR/IFR stratus returning to the coastal terminals around 04Z, progressing to the interior terminals after 12Z. Along the coast, winds are westerly 7-12 knots with light and variable winds across the interior. Winds will become more westerly and increase to 8-15 knots across western Washington Wednesday afternoon.

KSEA...VFR expected for the next 24 hours. A return of broader onshore flow on Wednesday will shift winds to the west- southwest between 12-16Z with speeds increasing to 6-9 kts after 18Z. Marine stratus returns early Thursday morning with probabilities for MVFR ceilings or lower increasing to 50% between 12-18Z Thursday.

MARINE

Thermally induced surface trough east of the Cascades. Low level onshore flow increasing this afternoon and evening. Gale force winds in the Central and Eastern portion of the Strait of Juan de Fuca tonight with small craft northwesterlies in Admiralty Inlet. Onshore gradients easing Thursday. Frontal system moving through the waters Friday with possible small craft advisory winds with and just behind the front. Winds easing over the weekend.

Choppy seas over the outer coastal waters through tonight with 7 to 9 foot swells with a 7 to 9 second period. The choppy seas will come to an end late tonight. Felton

FIRE WEATHER

One more day of elevated fire weather concerns. Even though the low level flow has turned onshore minimum relative humidities will still drop to near 30 percent this afternoon. Increasing low level onshore flow tonight with the marine layer making it all the way to the Cascade foothills Thursday morning.

Wetting rains along the coast Thursday night and Friday with a chance of wetting rains inland. Cool and unsettled weather over the weekend continuing into the first part of next week. Felton

SEW WATCHES/WARNINGS/ADVISORIES

WA...Heat Advisory until 11 PM PDT this evening for City of Seattle- Downtown Everett / Marysville Area-Eastern Kitsap County- Eastside-Foothills and Valleys of Central King County- Foothills and Valleys of Pierce and Southern King Counties-Foothills and Valleys of Snohomish and Northern King Counties-Lowlands of Pierce and Southern King Counties-Shoreline / Lynnwood / South Everett Area.

PZ...Gale Warning from 6 PM this evening to 6 AM PDT Thursday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory from 6 PM this evening to 2 AM PDT Thursday for Admiralty Inlet.

Small Craft Advisory until 6 AM PDT Thursday for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm- Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm.