Thursday Smoke Update

Wildfires in central and eastern Washington showed extreme fire behavior on Wednesday. In particular, the Wildcat Fire was intense enough to tap into mid-level moisture and generate its own thunderstorm, also known as a pyro-cumulonimbus cloud. Later in the evening, the Lower Sugarloaf Fire did the same thing!

Fires burning actively across Washington and British Columbia on Wednesday, September 4. A fire-generated thunderstorm, or pyro-cumulonimbus cloud, can be seen first above the Wildcat Fire in Yakima County and then above the Lower Sugarloaf Fire in Chelan County. Image via CIRA/RAMMB.

Fire-generated thunderstorm over the Wildcat Fire on Wednesday, September 3, viewed from the Paradise Visitor Center at Mount Rainier National Park. Photo courtesy Tom Banse.

With the fire activity across British Columbia and Washington, much of the state is now under a blanket of wildfire smoke. An air quality alert is in effect for all counties of central and eastern Washington through the weekend and possibly beyond. The alert will be re-evaluated on Monday.

GOES-18 satellite imagery valid 8:36 a.m. on Thursday, September 4.

Despite the hazy skies, not all of Washington is experiencing poor air quality at the surface. In fact much of western Washington, especially west of I-5, is experiencing GOOD air quality due to the influence of onshore flow and marine air in the lower levels of the atmosphere. 

That being said, air quality is certainly deteriorated across the Cascades and much of eastern Washington, ranging from MODERATE to HAZARDOUS. Impacts are particularly notable across the Methow Valley, much of NE Washington, and around the Wildcat Fire. Locally near Lake Cushman, air quality is also significantly deteriorated due to the Bear Gulch Fire.

Air quality index measurements via the EPA Fire and Smoke Map, valid 11:46 a.m. on Thursday, September 4. The worst impacts are evident in Northeastern WA, Yakima County/Mt. Rainier, and near Lake Cushman. 

Air quality across central and eastern Washington is expected to remain poor or even get worse in some areas through the weekend. In western Washington, light easterly flow will also pull smoke overhead, though the expectation is that most of the heavier smoke concentrations will remain at elevations above 1,000'-2,000', with less concentration at the surface in the Puget Lowlands. That being said, it will be a very smoky weekend in the higher elevations of the Cascades. Keep in mind, this is just a forecast. With this much smoke moving overhead, it's recommended to check current air quality conditions often for anyone across the state.

Cross-section from the HRRR smoke model, valid at 5:00 a.m. Saturday morning. Heavy smoke is likely in the Cascades and Columbia Basin. The model indicates relatively less smoke at the surface in Puget Sound. 

Going forward, there could be modest clearing on Sunday into Monday, especially in western Washington and through the Columbia Gorge as stronger onshore winds arrive. Cooler temperatures and some moisture next week should help with control efforts on some of the large fires across the state, but it likely won't be enough to put the fires out. Smoke will continue to affect portions of eastern Washington as long as those fires continue to burn. 

Additional blog updates will continue through the duration of this smoke event.