Another day at PL5 for the National Interagency Coordination Center, which makes 23 days consecutive in 2015 at either PL4 or PL5. This may feel like a long time to those of us dealing with fires in our region (and in my case, several days in a row of being smoked in), it's actually still below the 10-year average and the long-term average (see figure above from NIFC). While most media and other resources tend to focus on either number of fires or total area burned, I tend to find that Preparedness Levels are a better measure of how "bad" fire season is. Why?
Number of fires is rarely a good indicator of fire season strength because it is so dependent upon highly variable human and lightning ignitions. Additionally, fire suppression is able to extinguish 99% of all ignitions. Fire size, or area burned, is also problematic because many of the largest fires occur in very remote areas and are often grassland or shrubland fires that can scorch 50,000 or even 100,000 acres in a single windy day. While these fires definitely have negative impacts, killing cattle and rendering rangelands un-grazeable for several years, they don't usually cost as much per acre to suppress because they impact fewer homes and less infrastructure.
Forest fires and fires primarily burning in the Wildland Urban-Interface require the most resources to fight, making them the most expensive per acre in terms of suppression costs. These fires become first priority for suppression resources because lives and homes are at risk. When enough of these types of fires are burning with extreme fire behavior at the same time, a larger proportion of national firefighting resources are committed to trying to stop them. Nationally, PL4 and PL5 are primarily reached when multiple Geographic Areas (GACCs) have multiple large fires that threaten homes and critical infrastructure. Today, for example, there are 4 GACCs at PL5 for the individual GACCs (Northwest, Northern Rockies, Northern California, and Great Basin), and the first three have all been at PL5 much of the month. So the national PL level is 5 as well.
2002 holds the current record (since 1990) in terms of number of days at PL4 or 5, due to an early fire season with large incidents in both the Southwest and the Rocky Mountains (including the Hayman Fire in Colorado). For NIFC to break that record this year, fire season in the west would have to stay severe well into September, with little to no rain and above normal temperatures. It is possible, but let's hope that's not the case.
Crystal Kolden studies wildfire as a function of human and climatic influences. After starting her career as a wildland firefighter in northern California, she is now a professor of Pyrogeography at the University of Idaho.