Dry and unstable conditions over the Cascades lead to increased smoke
The high pressure peak responsible for our warm, dry weekend is peaking in strength today, bringing warm, dry conditions to much of the state. During the active fires in the Cascades, unstable conditions developed resulting in more active burning periods in the afternoon hours. Besides light winds and cool nights, smoke can easily get trapped in valleys and drain on either side of the Cascades.
The image below shows where smoke settled last night on the fires in the central and northern Cascades:
The ongoing fires in the Cascades are responding to today’s warm, dry, unsettled conditions by burning very actively this afternoon, producing more smoke than in at least two weeks. The National Weather Service has issued red flag warnings for falls over 2,000 feet, where the fuel is dry and conditions are right for fires to experience rapid growth.
The image below shows where active fires are emitting smoke this afternoon:
The smoke will continue to affect the eastern parts of the Puget Lowlands until Wednesday morning, when westerly winds will blow from the coast with increased chances of rain. Areas in the Cascades, specifically towns along Hwy 2, Hwy 12, and in the Wenatchee Valley, will continue to see smoke effects through Thursday afternoon. A cold front will drive strong westerly winds through the Cascade Mountain Range on Wednesday with increased chances of rain by Wednesday night. Rain will likely hit all the fires in the Cascade area between Wednesday night and Thursday morning, ending the smoke trail for at least a day or two.
Another ridge will form over Washington on Friday and will continue through the weekend, with weather conditions very similar to what we saw this weekend. Smoke effects are likely to return in this time frame, but with wet rains, air quality deterioration will be limited to areas closest to active fires.