Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
Issued by NWS Seattle/Tacoma, WA
107 FXUS66 KSEW 051058 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 358 AM PDT Sun Oct 5 2025 .SYNOPSIS...High pressures will bring dry and mild weather through early this week. Expect cooler and cloudier weather by midweek with stronger onshore flow. Low pressure will spin offshore over the latter half of the week then shift inland over the weekend. && .SHORT TERM /TODAY THROUGH TUESDAY/...Dry, north, flow prevails across western WA today with a ridge offshore. We may see patchy low clouds and fog over the south sound and coast, otherwise expect clear skies. Temperature trends will track close to average and in the mid 60s. High pressure shifts inland on Monday with winds turning light offshore. Temperatures will be slightly warmer with highs reaching the lower 70s. The ridge flattens over the region on Tuesday but the low level air mass will remain warm/mild with ongoing offshore flow. The Cascade foothills and valleys will reach the mid 70s for highs with mid 60s to lower 70s elsewhere. The flow will turn onshore Tuesday night as a weak front moves through. We`re not seeing too much precip with this front with just a trace to a few hundredths if anything. 33 .LONG TERM /WEDNESDAY THROUGH SATURDAY/...With a flip to onshore flow, expect cooler and cloudier conditions moving into Wednesday. Thereafter, low pressure will spin offshore Thursday and Friday with generally mild conditions. Some moisture may advect north into western WA for a chance of rain, although ensemble QPF is light. Rain chances increase over the weekend as the low eventually shifts inland. 33 && .AVIATION...A mix of ceilings and visibilities early this morning across Western Washington terminals. A low cloud deck over eastern Puget Sound is bringing low ceilings to terminals in the vicinity ranging from MVFR to LIFR. Latest METAR obs show fog has developed over PWT and with obs showing relative humidity values in the 90s, fog is possible for terminals along the coast, southern interior, and northern interior. Conditions should improve in the afternoon to VFR after 18z-21z for all terminals and should generally persist through the end of the TAF period. Winds will increase this morning after 11z-13z through the evening; winds will generally be N/NE at 8- 12 kt. Winds will ease Sunday night into Monday`s overnight hours. KSEA...A low cloud deck over Puget Sound brings MVFR ceilings to the terminal early this morning, with improvement expected after 18-19z. Winds will increase out of the N/NE to 8-11 kt today, likely overlapping low ceilings between 11z-19z. Winds will ease Sunday night into early Monday morning to around 6-7 kt. Guidance does suggest that MVFR ceilings may return Monday morning (25-35% chance). 29 && .MARINE...High pressure over the coastal waters, with a thermal through building northward along the coast today through Tuesday. As a result, surface flow will turn offshore across area waters at times. Winds in the central and east portions of the Strait of Juan de Fuca will increase early this morning and may approach small craft criteria. However, held off on issuing a Small Craft Advisory as probabilities were not very favorable. Probabilities of exceeding 21 kt in the central Strait are 10-25% for sustained and 20-40% for gusts. As for the eastern Strait, probabilities of exceeding 21 kt are 10-15% for sustained and 40-60% for gusts. Although these probabilities depict low to medium chances, an occasional gust exceeding 21 kt cannot be ruled out. A weakening frontal system will move over the waters on Tuesday and winds will shift more onshore. In addition, this will cause increased northwesterlies across the coastal waters. Latest guidance suggests that winds may meet small craft thresholds. Chances of sustained winds and gusts exceeding 21 kt are 40-60% and 50-80%, respectively. Highest probabilities are for the outer coastal waters. In addition seas will also build on Tuesday to 8-11 ft. Additional weak systems may move across the area waters later in the week. 29 && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...None. && $$