textproduct: Seattle/Tacoma

SYNOPSIS

Troughing developing over the area will continue into this weekend, bringing unsettled conditions and cooler temperatures to the region. Ridging looks to rebuild through the first half of next week for a slow warming trend.

SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/

An upper level trough over the region will bring onshore flow, cooler temperatures, and unsettled weather to western Washington over the next couple of days. As troughing deepens into Friday, an upper level low will develop offshore of Vancouver Island. Another round of morning clouds on Friday with a slight chance of drizzle in the morning. Dry conditions through Friday with high temperatures once again in the upper to lower 70s across the region. The upper level low will move onshore on Saturday, bringing widespread rain showers to to the region. Additionally, there is a 15-25% chance of thunderstorms, primarily south of Snohomish County at times throughout the afternoon. Winds may be breezy at times in and around showers. High temperatures remain in the mid to upper 60s, while overnight lows stay in the mid 50s.

LONG TERM /SUNDAY THROUGH THURSDAY/

Conditions look to start drying out into Sunday, with some lingering showers likely in the Cascades and the Olympics. An upper level ridge will begin to build offshore on Monday, introducing a slow warming trend through midweek. Some ensembles suggest weak troughing Tuesday/Wednesday that could bring some PoPs to the region, but for now, looks like dry and warm conditions will manifest.

Mazurkiewicz

AVIATION

Northwesterly flow aloft this evening and overnight before turning more zonal mid-morning Friday. Many terminals seeing light and variable winds this evening while the remainder typically seeing southwesterly to westerly winds generally 4 to 8 kts. Models continue to suggest that majority of terminals should favor a more southwesterly flow with speeds in the latter range very late tonight and carrying through into late Friday afternoon.

Widespread VFR conditions persist over W WA this evening. Isolated MVFR conditions are present along the coast and current satellite imagery /as of 03Z/ shows isolated patches of lower cigs beginning to develop here and there. Post-frontal onshore flow should be enough to nurture cigs falling throughout the overnight period with widespread MVFR to isolated IFR conditions in place by 12-15Z early Friday morning. Recovery to VFR conditions will be slow with terminals breaking out around 20Z or 21Z Friday afternoon and remaining there for the rest of the TAF period.

KSEA...VFR cigs this evening gradually lowering overnight to MVFR by 12-14Z and remaining there for the remainder of the morning and into early afternoon. Later breakout akin to earlier Thursday with cigs returning to VFR after 20Z. Clouds continue to lift and break up for remainder of TAF period, but not clearing out completely. Light and variable winds this evening and early tonight before increasing slightly in speed from the SW...generally 4-8 kts...and staying there for much of Friday.

18

MARINE

Post-frontal winds still seeing occasional gusts up to 25 kts this evening and as such, inherited small craft advisory will continue through 5 am Friday morning for both winds and seas of 8 to 11 ft. Another frontal system will move across the waters Friday into Saturday. Neither impactful winds nor seas are expected with this system, although portions of the southern interior and coastal waters will have a 20% chance of showers and thunderstorms from this system. Conditions will become more benign going into next week as high pressure rebuilds over the coastal waters. Seas decrease this weekend into next week down to 4-6 ft.

HPR/18

FIRE WEATHER

A return to onshore flow will maintain cooler and more moist conditions across western Washington through the weekend. Light precipitation is likely late Friday into Saturday as another weak system moves over the region. Conditions are expected to gradually warm and dry into next week, though fire weather concerns remain low at this time.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory until 5 AM PDT Friday 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.