Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
Issued by NWS Seattle/Tacoma, WA
774 FXUS66 KSEW 102159 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 259 PM PDT Wed Jul 10 2024 .SYNOPSIS...An upper level ridge remains over Western Washington through the weekend with continued low-level onshore flow. This will maintain above normal temperatures, but still notably cooler than the start of the week. Little change through the week ahead, with no rain expected and only subtle variations in the strength of the marine pushes each night. && .SHORT TERM /TONIGHT THROUGH SATURDAY/...A much cooler afternoon across most of the area today than this time yesterday, with temperatures generally running 5 to 10 degrees cooler than 24 hours ago. The overall pattern will not change too much through the remainder of the week with high pressure in place over the region and light onshore flow maintaining some cloud cover along the coast, into the lower Chehalis valley, and also through the Strait of Juan de Fuca. This will remain a somewhat shallow push though - enough to bring the cooling marine influence progressively into the interior, but unlikely to bring stratus to fill the interior. This will bring overnight lows back down into the 50s and closer to seasonal normals, while abundant sunshine will maintain highs in the 80s. .LONG TERM /SUNDAY THROUGH WEDNESDAY/...Strong ensemble agreement to support very little impactful changes to the weather pattern in the first half of next week. Expect continued influence from high pressure aloft with onshore low-level flow persisting through the week. This will bring additional rounds of stratus pushes in the morning and plenty of afternoon sun for most, along with high temperatures generally in the 80s through the interior. A weak disturbance around Monday or Tuesday may be responsible for a slightly deeper push of marine stratus and favor temperatures more in the lower 80s as opposed to mid to upper 80s, but that`s really the biggest change in the day to day pattern through the next week. && .AVIATION...Upper level ridging over the central US with weak troughing over the eastern Pacific will keep SW flow in place aloft into tonight before becoming more zonal overnight. Surface winds for most terminals will see transition from southwesterly during the early afternoon to more westerly through late afternoon. Early evening should bring more northwesterly winds to the region with speeds generally 8-10 kts, before becoming light and variable overnight. Exceptions will be HQM and CLM, where westerly marine push will be dominant direction and BLI, where winds will remain southerly throughout the TAF period. Widespread VFR conditions in place and are expected to remain that way for most sites through the majority of the TAF period. Onshore push overnight may allow for MVFR to IFR conditions impact HQM and PWT as marine stratus seep inland. PWT will likely see skies improve first...by around 18Z Thursday while HQM will likely wait to break out in the early to mid afternoon hours. KSEA...VFR throughout the TAF period. Above surface wind discussion applies. 18 && .MARINE...Surface ridge over the NE Pacific will strengthen just off the coastal waters through the week. A gradual increase in onshore flow is expected over the area...resulting in gales forecast for the central and eastern Strait. Current obs show Race Rocks blowing gale speeds, however surrounding obs are far lower...barely reaching SCA level winds on gusts. Expectation is for these speeds to increase during the early evening, so will leave inherited headline in place. Forecast also suggesting SCA level winds emerging in the outer coastal waters overnight...however this might be slightly overdone. Have capped winds there at 15 to 20 kts with potential to reach SCA during the day tomorrow. Will advise future shifts to monitor, as an SCA for this area is not too far out of the question. Persistent onshore flow will remain in place into the weekend with diurnally driven westerly pushes through the Strait, possibly accompanied with additional headlines. Seas generally 4 to 6 ft before increasing to 6 to 8 ft Thursday and nearing 10 ft by Friday for the outer coastal waters. 18 && .SEW WATCHES/WARNINGS/ADVISORIES... WA...Heat Advisory until 5 PM PDT this afternoon for Bellevue and Vicinity-Bremerton and Vicinity-East Puget Sound Lowlands- Everett and Vicinity-Hood Canal Area-Seattle and Vicinity- Tacoma Area-West Slopes North Cascades and Passes-West Slopes North Central Cascades and Passes-West Slopes South Central Cascades and Passes. PZ...Small Craft Advisory until 5 PM PDT this afternoon for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca. Gale Warning from 5 PM this afternoon to 5 AM PDT Thursday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca. && $$