702 FXUS66 KSEW 140239 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 739 PM PDT Sun Apr 13 2025 .SYNOPSIS...Conditions expected to remain dry into Friday. High pressure over Western Washington will continue to bring warmer temperatures through Monday. On Tuesday high pressure will weaken as a weak disturbance moves across the region. Conditions will warm up again on Thursday and Friday as high pressure rebuilds. Precipitation chances return next weekend. && .SHORT TERM /TODAY THROUGH WEDNESDAY/...No updates to the forecast this evening. Cirrus clouds are beginning to stream in and will continue to move through the area tonight and into tomorrow. Upper level ridging over the area will bring warmer temperatures on Monday, with daytime highs generally in the mid- to-upper 60s (warmer temperatures in the 70s possible in the southern interior valleys). In addition, Monday`s overnight temperatures will rebound into the upper 30s to low 40s. On Tuesday, the ridge will weaken and a shortwave trough will move over the region. Models are in good agreement that the bulk of the precipitation will stay in British Columbia. If any precipitation does make it into Western Washington, it will be limited to the Northern Cascades. Daytime temperatures will also cool slightly on Tuesday. High temperatures on Tuesday will be in the upper 50s along the coast and mid 60s in the lowlands. By Wednesday, high temperatures will be in the upper 50s to low 60s. An upper level ridge will continue to intensify offshore Tuesday and Wednesday. Ensemble and deterministic models are in general agreement that a low will drop down from Canada on Wednesday. Previously the GFS had the low pressure center passing over Central Washington (a much wetter solution for Western Washington). However, the latest run has the low pressure center moving along Eastern Washington/Idaho. This eastern trajectory is seen as well with the European model and WPC cluster analysis. With models starting to agree on a solution, Wednesday is looking to remain mostly dry (some precipitation possible along the Cascades but PoPs are low around 20-25%). .LONG TERM /THURSDAY THROUGH SUNDAY/...A strong upper level ridge will move into Canada on Thursday and slowly make its way towards Western Washington. Ensemble guidance is in good agreement for a strong ridge to move onshore on Friday. Daytime temperatures will gradually warm up Thursday into Friday (may see some low 70s on Friday in a few locations). Solutions begin to differ on Saturday and Sunday. The European model has the ridge axis further east along the Rockies on Friday and rain chances arriving as early as Saturday. However, the GFS model still has the ridge axis over Washington on Saturday and rain chances returning on Sunday. At this time, the European model is better aligned with ensemble guidance solutions, with a majority of ensemble members having the ridge axis along the Rockies by Saturday and a trough moving into Washington Saturday and Sunday. 29 && .AVIATION...High pressure with dry and stable conditions across western Washington. VFR conditions will prevail through the period. 33 KSEA...Mostly clear skies, VFR conditions, with N winds 5-10 kt. 33 && .MARINE...A thermal trough will develop along the coast with light offshore winds through Monday. A weakening cold front will cross the coastal waters Monday night, with N/NW winds increasing over the outer coastal waters. Seas building to 10-14 feet on Tuesday, primarily for the outer coastal waters. High pressure off the coast will maintain onshore flow moving toward midweek. 33 && .HYDROLOGY...No river flooding expected in the next 7 days. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...None. && $$