Rainfall over the weekend has helped temper the wildfire season for now, though hot, dry conditions later this week could undo any positive developments. At the same time, many parts of the state are experiencing poor air quality due to wildfire smoke arriving from Oregon.
The quarter inch of precipitation in Eastern Washington arrived at a key point in the season when wildfires either start or fail to ignite depending how moist the light fuels are. If wet, those fuels take roughly a hundred hours to dry, while heavier fuels require a thousand hours – though they also take longer to absorb moisture. Forestry experts have previously noted that a wildfire season’s severity is often determined by how much rain the region experiences during late July and early August.
University of Washington Atmospheric Sciences Professor Cliff Mass wrote in a blog post that the quarter inch of rain over the weekend fell “exactly where we needed it to lessen the wildfire threat. (The) wildfire threat is way down and this gives firefighters a chance to gain an upper hand. All and all, a very favorable situation.”
State Department of Natural Resources (DNR) Fuels Analyst Vaughn Cork told Lens that despite the rain and lower temperatures it’s “not enough to change our drought status a whole lot. We need things to come through for a long period to really have any impact to those heavier fuels.”
In the latest weather report for DNR, National Weather Service meteorologist Samantha Borth wrote that rain has also increased the relative humidity (RH) in Eastern Washington from 10 percent to as high as 50 percent. According to the U.S. Forest Service’s seven day fire potential outlook, Central Washington remains at low risk, while Eastern Washington is at a moderate risk of significant wildfires.
Cork said that anticipated rain later this week will be “a bigger help than just what we got yesterday and on Saturday.” Yet, he also warns in a fuels report that “there is a chance for it to be preceded by lightning, and given the fuel status, very high ignition efficiency should be expected.”
Although most wildfires are caused by humans, lightning strikes tend to ignite the most severe wildfires.
Cork added that “the weather pattern is really going to set the stage. If we continue with closer to normal weather, that impact (of rain) will be longer.”
In the meantime, Governor Jay Inslee’s burn ban declaration still allows for burns where permits had already been issued. Washington Policy Center Agriculture Director Pam Lewison says that policy should be changed not only to prevent new wildfires but also to improve air quality in areas of the state where it’s currently unhealthy or even hazardous.
“If we are going to have a burn ban…it should be a wholesale burn ban,” she said. “It should not matter if you have a burn permit or not. It poses a pretty great risk.”
There are currently 12 wildfires ongoing in the state, eight of them large wildfires (100 acres or more). The largest so far this season remains the Dry Gulch Fire, which has consumed 80,000 acres and is 90 percent contained. The season has also primarily affected Central and Eastern Washington, with just under 300 acres burned west of the Cascades.