364 FXUS66 KSEW 260329 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 829 PM PDT Fri Jul 25 2025 .UPDATE...Mostly clear conditions this evening with lingering stratus along the coast and high clouds for northern areas. Clouds will increase again later tonight into Saturday morning with increasing onshore flow due to generally zonal flow aloft. Temperatures will be a couple degrees warmer on Saturday for highs, mainly in the mid 60s to mid 70s. && .SYNOPSIS...Zonal flow will continue into Saturday, maintaining cooler and cloudy conditions across western Washington. Southwest flow aloft will begin to develop on Sunday, kicking off a warming and drying trend with chances for thunderstorms towards the middle of next week. && .SHORT TERM /TONIGHT THROUGH MONDAY/...With low pressure to the north and high pressure to the south, zonal flow aloft will continue to bring moist onshore flow to western Washington through Saturday. High temperatures will be limited by the cloud cover this afternoon, reaching the upper 60s to near 70 and the upper 50s to near 60 along the coast. The weak trough over British Columbia will shift further inland on Saturday, bringing a repeat of cooler and cloudy conditions to western Washington. However, slightly less cloud cover on Saturday afternoon may allow temperatures to peak a degree or two warmer than today. A warming trend will begin on Sunday as a high pressure ridge begins to build over the south central US and a low pressure system deepens over the Gulf of Alaska. While conditions will stay dry through Monday, flow aloft will turn southwesterly and allow temperatures to warm up several degrees. Highs will return to near seasonal averages on Sunday and Monday with plentiful afternoon sunshine. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...A deep upper level low will churn offshore through the extended period, generating southerly flow aloft over western Washington and injecting periods of moisture northward. Ripples in the southerly flow may generate thunderstorms throughout the week, especially over the Cascades and Olympics, where ensembles show potential for MUCAPE values as high as 500-1000 J/kg. While the exact details remain highly uncertain at this time, the threat for storms continues to be closely monitored. 15 && .AVIATION...The stratus has finally managed to scatter out this evening, with the stratus staying put offshore for now. Another marine push is expected Saturday morning, bringing area-wide MVFR ceilings. In addition, guidance hints at a 20-40% chance of IFR ceilings, with the highest probabilities along the Kitsap Peninsula and coast. Some mist and drizzle is also possible. Improvements to VFR expected after 18-21Z, although coastal terminals will may remain MVFR due to onshore winds. A westerly push across the Strait of Juan de Fuca will keep northwesterly winds across Puget Sound this evening/tonight (from KSEA to KPAE), and will become more southwesterly Saturday morning. KSEA...VFR ceilings this evening. Another marine push is expected to bring stratus/mist and possible drizzle in the morning (as early as 12Z), lowering conditions to MVFR. Conditions expected to improve after 18-21Z. Guidance hints at a 20-25% chance of IFR Saturday morning. Northwest winds this evening at 4-5 kt will become more southwesterly Saturday morning at speeds of 4-6 kt. 29/HPR && .MARINE...An upper level trough will bring increasing onshore flow today over the region. The trough will remain in place through Saturday before moving inland. A larger low will dip down from Alaska offshore through next week. For this weekend, the onshore marine pushes may bring stratus and mist/fog over portions of the waters Saturday morning (especially the inner coastal waters). Diurnal pushes through the Strait of Juan de Fuca will continue through the weekend. A small craft advisory continues for the central/east Strait of Juan de Fuca this evening, and the push Saturday evening/Sunday may produce gusts and potentially sustained small craft winds. Coastal seas will remain Seas will remain 5 feet or less throughout the weekend through next week. HPR && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory until 2 AM PDT Saturday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca. && $$