The upper-level ridge will gradually move over the Pacific Northwest through the coming weekend, keeping the atmosphere stable. The wildfires in the Willamette Valley are creating their own weather pattern, which will persist through the coming weekend. Surface winds will be from the SW, and fairly light on Friday, yet transport winds will remain NE as the wildfires in Marion and Clackamas Counties sustain offshore flow over the Cascades. The ridge overhead will limit mixing, keeping skies muffled under dense smoke and haze. Temperatures will remain near or slightly below seasonal averages where smoke is dense, but well above seasonal averages in the northern Willamette Valley, meaning warm & dry air will continue surround the Silverton Hills.
A modest sea breeze will move in Friday evening, turning surface winds NW and bringing in cooler air. Saturday morning will see morning clouds and patchy fog west of the Willamette River, and the strength of Saturday’s sea breeze in the afternoon will determine if fog will begin to push east of the river Sunday morning and help local firefighters. The interactions between cool & moist air to our west with smoky, drier air to the east will keep visibility fairly low, with only limited improvement during daylight hours.
The National Weather Service’s digital forecast is available at: https://oda.fyi/NWSForecast