Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
Issued by NWS Seattle/Tacoma, WA
644 FXUS66 KSEW 310344 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 844 PM PDT Thu Jul 30 2026 .SYNOPSIS... High pressure will lead to warmer weather on Friday. A system will track through western Washington on Saturday for cooler, wetter and windier conditions. A ridge will bring warmer and drier conditions early next week. && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... There is weak upper level troughing over the region with ongoing low level onshore flow. The result is near-normal conditions with highs in the 60s and 70s. A system will spin off B.C. on Friday with a front stalling offshore. The air mass will be a little warmer with weak ridging over the Northwest. Interior lowland temperatures will reach the low to mid 80s with 60s and 70s along the coast. Saturdays weather will be cooler, cloudier and wetter as the front and upper low track inland. Highest chances for wetting rain will be over the north coast and north Cascades. There is also a slight chance of thunderstorms in the north Cascades Saturday afternoon. Winds will be breezy too with S/SW gusts to 20-30 MPH across most lowland areas (winds peaking during the afternoon). Showers with a convergence zone will be focused over Snohomish County Saturday afternoon and may linger into late Saturday night. 33 && .LONG TERM /SUNDAY THROUGH THURSDAY/... The upper level departs to the N/NE on Sunday with weak troughing left over WA. We`ll remain cooler than average with highs in the 60s to lower 70s. It will be drier, though, with just a few light showers noted over the Olympics and northern Cascades. High pressure builds early next week for warmer and drier conditions. The flow will turn offshore as a thermal trough forms along the coast. Expect a rise in temperatures with interior lowland areas seeing the 80s to lower 90s. Overnight lows will be mostly in the 50s. This will result in widespread Minor Heat Risk with pockets of Moderate Heat Risk across the south interior (away from the water). 33 && .AVIATION... Southwest flow aloft continues into Friday with an upper trough offshore and upper ridge over the interior West. The low level flow is light onshore. Areas of IFR/LIFR stratus will redevelop overnight along the immediate coast, otherwise VFR conditions will prevail at the interior terminals. Improvement at the coast possible briefly Friday afternoon, before deteriorating in the evening again. KSEA...VFR and mostly clear skies. Surface winds WNW this evening, becoming NNE Friday morning, then WNW in the afternoon again. Winds will become SW after 07Z-09Z at 5-8 kt. 27/29 && .MARINE... High pressure will remain over the waters through Friday. Another weak system will reach the waters Friday night and Saturday. High pressure will rebuild over the coastal waters Sunday and remain in place through Monday. Small craft advisory strength westerlies are likely in the central/east strait Friday evening becoming gale force late Saturday afternoon into Saturday evening. 27 && .FIRE WEATHER... Drier and warmer conditions are forecast for Friday due to weak upper level ridging. Daytime min humidities will dip into the 30s across the Black Hills and SW Interior lowlands, SE Puget Sound lowlands, and Cascade valleys. A system on Saturday will bring wetting rain to the north coast and north Cascades (with a chance of thunderstorms). It will be windy with gusts near the crest in the 30-40 MPH range. However, with the wetter and cooler conditions, min RHs will not reach critical thresholds. Warmer and drier weather early next week will keep the fire weather threat elevated, especially next Tuesday and Wednesday, where min RHs will dip into the 20s and 30s again. 33 && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...None. && $$