


Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
Issued by NWS Seattle/Tacoma, WA
902 FXUS66 KSEW 152211 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 311 PM PDT Tue Jul 15 2025 .SYNOPSIS...The dry and very warm pattern will continue through Thursday with elevated and even critical fire weather conditions for parts of western Washington, and widespread moderate HeatRisk. More moderate temperatures and continued dry conditions will return to the area Friday into the weekend. && .SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...Building upper level high pressure and the thermally induced surface trough moving up from Oregon have pretty quickly boosted temps this afternoon. Temperatures already running anywhere from 10 to 25 degrees warmer than this time yesterday. The low level northeasterly flow will continue overnight will limit overnight cooling over much of the area. This will especially be true for locations with even a slight easterly component to the wind where overnight lows will remain in the low 60s. Spots near the water or with little or now wind may manage to drop into the upper 50s. Wednesday remains on track for the warmest day, with warm temps aloft and the thermally induced surface trough over the area in the morning. Highs over the interior will reach into the upper 80s to mid 90s. For the coast, burgeoning onshore flow with the surface trough shifting east will limit the warming there to the 70s and perhaps low 80s. The low level onshore flow Wednesday night into Thursday is not expected to be fully developed - will likely result in a warm - but somewhat cooler day for much of the interior Thursday with high in the 80s. Widespread moderate HeatRisk conditions will linger across much of Western Washington through Wednesday with some improvement Thursday. The heat advisory remains in effect through 10 pm Wednesday. && .LONG TERM /FRIDAY THROUGH TUESDAY/...Ensembles continue to agree on the a cooling trend becoming more fully established Friday with a more typical low level onshore flow pattern continuing through the weekend. This will result in near- or even below-normal temperatures. but continued dry through the weekend. The only exception is the odd chance at light showers over the northern Washington Cascades Sunday and again Monday with weak upper level systems brushing the area. Highs in the 70s and lower 80s Friday lowering to the upper 60s to mid 70s Sunday and Monday. && .AVIATION...VFR conditions will prevail through the TAF period, with the exception of KHQM. Guidance hints at IFR/LIFR conditions returning early Wednesday morning after 7z-9z, with improvement expected after 19z-21z. Breezy northerly surface winds this afternoon/evening across Puget Sound terminals 10-14 kt, with gusts around 15-20 kt possible. Winds will ease overnight and become slightly more northeasterly. Winds will become more westerly Wednesday morning into the afternoon. KSEA...VFR conditions expected to prevail with mostly clear skies. Breezy northerly winds this afternoon around 11-14 kt, with gusts up to 20 kt possible. Winds will become more northeasterly overnight and subside to 3-6 kt. Guidance hints at winds becoming westerly Wednesday around 16z-19z. 29 && .MARINE...Surface high pressure will retreat west into the NE Pacific with a surface trough expected to move over the waters on Wednesday. This will bring increased wind speeds across the coastal waters late Wednesday morning through early Thursday morning. The strongest winds will be in the outer coastal waters, with gusts having the potential to reach up to 30 kt. As a result, a Small Craft Advisory has been issued. In addition to winds, seas will build 8-11 ft for the outer coastal waters by Wednesday evening. Moving forward, high pressure will remain over the NE Pacific and will begin to rebuild over area waters on Friday into the weekend. Waves will be on a decrease trend Thursday and Friday to around 6-9 ft, with waves 5 ft or below through the weekend into early next week. Westerly pushes across the Strait of Juan de Fuca will occur each evening with onshore flow returning with varying degrees of strength. The push across the Strait on Wednesday and Thursday look to remain below advisory criteria. However, the pushes on Friday and may meet lower-end small craft thresholds. 29 && .FIRE WEATHER...Widespread elevated fire weather conditions will continue into Thursday. The Fire Weather Watch for the southwest WA lowlands was cancelled due to no longer expecting the onshore gradient to develop quickly enough to result in a strong push of wind, while the relative humidities remain low. The watch for the Cascade mountains zones 658 and 659 was upgrade to a Red Flag Warning. Depending on the placement of the thermal trough, expect to see a deeper mixed layer and increased instability over the Cascades with mixing heights potentially rising into Wednesday. Wednesday will have the worst fire weather conditions for existing incidents and the potential for any new ones if they were to begin. Cooling trend beginning Thursday with temperatures dropping below normal Saturday. Minimum RH values increasing Thursday into the weekend with the return of low level onshore flow. Felton/Bower&& .HYDROLOGY... && .SEW WATCHES/WARNINGS/ADVISORIES... WA...Red Flag Warning from 11 AM to 11 PM PDT Wednesday for West Slopes of the Central Cascades Generally above 1500 Feet- West Slopes of the North Cascades Generally above 1500 Feet. Heat Advisory until 10 PM PDT Wednesday 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-Foothills and Valleys of Thurston and Lewis Counties-Foothills and Valleys of the North Cascades- Lowlands of Lewis and Southern Thurston Counties-Lowlands of Pierce and Southern King Counties-Lowlands of Western Skagit and Northwestern Snohomish Counties-Lowlands of Western Whatcom County-Middle Chehalis River Valley- Northern Hood Canal-Olympia and Southern Puget Sound- Shoreline / Lynnwood / South Everett Area-Southern Hood Canal. PZ...Small Craft Advisory from 11 AM Wednesday to 5 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. && $$