Below-Normal Wildfire Year so Far

Even with a relatively dry spring,  cumulative wildfire acreage in Washington State is currently below normal.  

You read that right, below normal.

Interestingly, the dry condition may have even contributed to the modest wildfire totals so far this year.

To start, consider the Washington State Department of Natural Resources (DNR) acres burned statistics for Washington State (below).  This year is very low...the second lowest since 2015.

Currently, there are only two significant wildfires burning in Washington right now, and both are relatively small:  the Pomas and Barstow Road fires (see map below).

While the wildfire season has been restrained so far, spring precipitation has been below normal, and temperatures have been above normal (see plots below).  

Western Washington has been particularly dry, with the Columbia basin modestly below normal.

So, how could the wildfire area be less with warmer and drier conditions?

Because wildfire generation is more complicated than communicated in the media, such as the Seattle Times.

To get a wildfire, you need ignition, sufficient fuels, dry fuels, and supportive meteorological conditions, with wind being the most important.

Precipitation during late winter and spring is important for producing bountiful light fuels, such as grasses and range-type vegetation.

Rainfall deficit has resulted in normal to lower than normal amounts of annual vegetation over much of the region, something shown by the USDA Fuelcast site (see graphic below).

Last weekend, I explored the situation in the hills north of Teanaway, WA on the eastern side of the Cascades.  Grass productivity was less than I have seen in recent years, and much of it was still green in forested areas (see pictures below).

So we start with a light to normal fuel load over much of the region.

What about ignitions?  

 Many utility companies are stating they will be more aggressive with strategic power shut-offs, which should help.   But what about lightning-initiated fires, which are often in remote areas and difficult to extinguish?

The extended precipitation forecast this summer is for drier than normal conditions (see below).  Since thunderstorms are the big precipitation producers for much of the summer (particularly east of the Cascade crest), this implies fewer thunderstorms.

Which means fewer lightning starts and fewer ignitions.  This implies less wildfire activity.

August and September are generally our big wildfire months.   The European Center's prediction of precipitation anomaly (difference from normal) is near normal for August (except north of the border) and perhaps wetter than normal over western Washington in September (see below).   Not very threatening.

All in all, I don't think there is much reason to expect an above-normal wildfire season over Washington, even with the teeth gnashing in a certain local paper.

David Horsey, Seattle Times