Western US Drought Part 3: Wildfires

This is the final blog post in the 3 part series on Western US Drought. The previous 2 posts were about the current drought outlook and some of the effects of drought. This post will discuss the drought's impact on wildfire season.

A satellite image from September 5, 2020 shows 5 major fires burning in California. These fires were large enough to form pyrocumulonimbus clouds (thunderstorm clouds made by heat from wildfires).

One of the biggest impacts of drought is increased wildfires. The North Carolina Climate Office describes it this way: "If the dry conditions persist, a drought can develop, leading to conditions favorable for wildfires as all the excess dried-out vegetation provides ample fuel for the fires. ... Wildfires will ignite very easily under such dry conditions and can spread quickly." 

Drought has exacerbated recent fire seasons, with fires getting bigger, longer, and fire season in general expanding and having longer boundaries. 

The Environmental Defense Fund writes: "Not only is the average wildfire season three and a half months longer than it was a few decades back, but the number of annual large fires in the West has tripled — burning twice as many acres."

Below is a graphic of the numbers of acres burned in the Western US in recent fire seasons. (This runs through the middle of the 2020 fire season).

Graphic found here.

Notice a clear upward trend in acres burned, with some years having less, but an overall trend of more and more scorched acres. By the end of the 2020 fire season, a record-breaking 10.1 million acres had been burned.

The most interesting thing about the major upward trend in acres burned is the fact that the severity of the Western US drought corresponds with more acres burned.

2020 was historically bad for wildfires. This graph below (found here) shows 2020's amount of acres burned compared to other years since 2001...and the graphic doesn't go through the full season.

The astounding amount of burned acres in 2020 was due to major drought combining with rare tropical moisture and some abnormal wind events to provide optimal conditions (lightning strikes, dry fuels) for massive wildfires. 

The August Complex Fire in Northern California burned an incredible 1 million acres in 2020, contributing to California's total of 4.5+ million acres burned in one season alone. This record amount was caused by extremely dry conditions in California, something that is already occurring this year due to little precipitation.

So...we have learned how drought can wreak havoc in fire season, increasing the length of the season and in turn the acreage burned. 

Now to answer the question...how will drought impact the upcoming fire season?

In part 1 of the drought series, I showed this graphic that shows percent of average snowpack. Since most of the Western US with the exceptions of WA, MT, and WY has below average snowpack, more fires are possible because fuels (what fires need to burn) are already dry and will ignite very easily across a large area of the Western US.

Many people worry about California in particular, where large and destructive fires have become the norm. This tweet from NIDIS Drought explains the forecast for 2021.

It can be assumed that any areas with dry vegetation and little precipitation (especially due to drought) will be more likely to be impacted by wildfires in the upcoming fire season.

In fact, fires are already burning. The National Interagency Fire Center (great resource for current fire news across the US) reports that 457,000 acres have burned in the US so far in 2021 (about half of the long-term average).

The fire season is average so far, but expect it to get worse through the next few months. This will not be the last blog about wildfires this year. Stay tuned for updates throughout the summer as wildfire season worsens.

Found here (WA DNR Twitter).

Found here.

Thank you for reading the Western US Drought series! I hope you have become better informed on the seriousness of the drought that is occurring across the Western US. If you enjoyed this series and would like more blogs like it, please leave a comment and let me know!