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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.
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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
The upcoming fire season, as far as acres burned, may end up being not so bad, as Cliff suggests. However, it won't be because the potential for a bad season is not there. We have had another very dry, warm spring, especially in the central Washington/Cascade east slope area, where historically our largest fires have occurred, and the outlook is for a dry, warm summer. While there may not be as much grass to burn this season, there is always plenty of forest fuels ready to burn on the ground and in the trees, and this is where the danger lies this year. These larger forest fuels have become much drier, much earlier than normal this year. The Pomas fire is an example of this, an early season fire burning well up in the normally wetter forest area which usually does not present a problem until mid summer. Yes, other factors, especially such as the nature of lightning activity this summer, are going to be critical. However, it is not the number of lightning storms that is important in starting fires so much as their nature. A few dry lightning outbreaks can start many fires, whereas many of our wetter storms do not start fires since the fuels are too damp to ignite. The late August 1970 lightning outbreak in the Wenatchee/Okanogan forest was a good example of this; there were not many lightning strikes from this storm but because it was so dry and the lightning occurred during a warm, dry stretch, almost every strike started a fire, which overwhelmed initial attack. So maybe we will escape the fate that Eastern Oregon faced last season, when dry lightning ignited many fires with a large loss, while Eastern Washington was mostly spared.
ReplyDeleteWxman.... there are some issues with your analysis. The Pomas fire did not start in moist virgin forest. This was a previously burned (2015) area with dead and downed timber. Lots of slash. Lots of open area with grass and bushes. Hard to image an area more ideal for fire...cliff
ReplyDeleteIt looks like David Horsey could lose some weight.
ReplyDeleteWhat does the temperature outlook look like?. The Cpc is forecasting a warmer than normal summer.
ReplyDeleteThis is fireworks season, ignitions expected.
ReplyDeleteI've read that in the last few years agencies have gotten better at coordinated and rapid response to human caused ignitions (about 84% such). A fire (Trail Creek) just 8 miles east of me was contained at about 50 acres.
Thomas Jefferson believed that the Fourth of July should be celebrated as the anniversary of American independence, stating it ought to be marked with "Pomp and Parade" and festivities across the continent. Nothing about starting wildfires!