


Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
Issued by NWS Seattle/Tacoma, WA
820 FXUS66 KSEW 052053 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 153 PM PDT Sat Jul 5 2025 .SYNOPSIS...A warming trend will begin the new week as an upper ridge strengthens over Western Washington. The ridge will weaken and onshore flow will increase for a brief cooling trend midweek before warmer conditions return as an upper ridge rebuilds. && .SHORT TERM /TONIGHT THROUGH TUESDAY/...The warming trend begins Sunday as flow aloft becomes more zonal. Interior temperatures will climb into the mid to upper 70s, with some locations in the Southwest interior and Cascade valleys reaching around 80F. By Monday, the upper level ridge strengthens in response to strong ridging over the Southwest US, leading to more widespread 80s across interior areas, particularly from Seattle southward. The ECMWF and GFS deterministic models, along with their respective ensembles, show strong agreement on the continuation and strengthening of the upper-level ridge through Tuesday. This will result in the warmest temperatures of the forecast period, with low to mid-80s across much of the Puget Sound region, and some areas pushing into the upper 80s. Moderate HeatRisk could be a concern on Tuesday. .LONG TERM /WEDNESDAY THROUGH SATURDAY/...Ensemble guidance indicates a flattening of the ridge as a trough crosses northern British Columbia. This will promote increasing onshore flow and a cooling trend. There`s a slight chance of a shower near the coast or North Cascades, but the overall forecast remains dry. Upper ridging returns late week with temperatures rising back above normal. && .AVIATION...Westerly flow aloft continues with onshore flow in the lower levels as an upper level trough moves eastward. VFR conditions at all of the terminals this afternoon with some high clouds moving across the area. This trend will continue throughout the evening with westerly winds increasing at KCLM and areas around Whidbey Island. Elsewhere, winds will turn northerly across the interior and generally be around 8 to 12 knots. VFR looks to continue into Sunday morning, although marine stratus may bring MVFR conditions to KHQM and KOLM throughout the morning. KSEA...VFR conditions will continue throughout the TAF period. Westerly winds this afternoon 4 to 8 knots will turn northerly around 23z-02z and increase in speed to 8 to 12 knots. Wind speeds will decrease by the morning but will remain northerly. Guidance is highlighting 20-25% chance of MVFR stratus nearing the terminal early Sunday morning, but confidence is low. VFR will likely prevail. Mazurkiewicz && .MARINE...Surface high pressure will continue to remain offshore throughout the weekend and into early next week. Diurnal westerly pushes down the Strait will continue over the next several evenings, especially this evening as a Small Craft Advisory remains in effect. A weak system may approach the area waters during the middle of the week with an uptick in winds and seas. Combined seas look to hover between 4 to 6 feet throughout the weekend and into the early half of next week. Seas may become steep at times with continuous northerly winds over the waters. Mazurkiewicz && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory until 3 AM PDT Sunday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca. && $$