Smoke from structure fires, wildfire likely to stick around the Willamette Valley

PORTLAND, Ore. (KOIN) -- The smell of smoke quickly started to overcome the Portland area late Tuesday night and isn't planning on moving out anytime soon.

The Longview paper mill fire caused the first round of poor air quality starting Tuesday night. The situation was made worse thanks to a massive fire at a vacant KMart building in Northeast Portland Wednesday morning. At times Wednesday, air quality in parts of the Willamette Valley reached the "unhealthy" level.

Health officials say during times of "unhealthy" air quality people should limit time and activity outdoors.

By Thursday morning, the smoke from those two structure fires will likely be replaced by wildfire smoke from the Flat Fire burning in Southern Oregon. Smoke from that nearly 13,000-acre blaze will pollute the skies over northern Oregon and southwest Washington Thursday.

Upper-level winds will help push the smoke from Medford to the Portland area through the day Thursday.

While forecasts show most of the smoke will dissipate by Friday afternoon as an onshore flow starts to ramp up, the threat of smoke is likely to continue over the next several weeks as the lack of rain keeps the wildfire threat high.

Hot and dry conditions are expected to last through the end of the week. Portland isn't expected to see any additional rainfall over the next week.