Will the Northwest be the focus of forest fires this year?
My friends at the Seattle Times are gearing up for their wildfire dramas again.
A headline on the front page suggested that the Northwest would be the “epicenter” of the US wildfires
and in the article they claimed that last year’s Bolt Fire was a
“rehearse for more frequent fires along the western slopes of the Cascades as climate change drives summer warming”
So what does reality say about the possibility of wildfires this summer? Is the scary hype based on sound science? Is climate change/global warming behind the Bolt Fire and this summer’s fires?
This blog will present some facts and give you a more in-depth and science-based insight than what you will see in the Seattle Times.
Statistics and current forest fire situation
So far, this has been a relatively normal to below-normal wildfire year in our region.
Check out the latest wildfire statistics from the Washington State Department of Natural Resources (below). These charts are for Washington State and are for DNR lands only, located primarily on the low fire-prone elevations of the area’s terrain.
We are running BELOW NORMAL for both number of fires and fire area.
Next, let’s move on to Northwest fire statistics from the Federal Northwest Interagency Coordination Center, which shows near-normal current fire counts (blue line). We were above normal in May and then the fires subsided again in the wetter weather over the past few weeks.
So far there have been very few forest fires. Most fires are grass/wildfires, and that’s certainly true of larger fires.
Why are grass/range fires significant?
The grass dries quickly in early summer (even after a rain, it will only take a few hours to dry enough to burn).
So we have a flammability threat east of the Cascades that has nothing to do with global warming. That was from previous wet conditions, contrary to predictions of global warming. All it takes is a little careless ignition in windy conditions to ignite a large swath of grazing land, and several such fires have occurred this spring.
Current humidity situation
We’ve had persistent conditions with near-normal humidity east of the Cascades (where most historic wildfires have occurred) and drier-than-usual conditions west of Washington. The current National Drought Monitoring chart shows this (see below)
More broadly, objectively, is the latest Palmer Drought Severity Index, which combines the effects of BOTH TEMPERATURE and rainfall. Conditions were near-normal in eastern Washington and wetter than usual in eastern Oregon. Western Washington is drier than usual.
As I mentioned in several blogs, the general atmospheric circulation over the West Coast was very irregular this past spring, with a low-pressure trough over California. This has dried up western Washington and Oregon while bringing wet conditions to California.
It also brought persistent thunderstorms and rain east of Washington, has lessened the threat of wildfires there (see sample image below from NWS).
As shown in the June precipitation map below, there has also been significant rainfall over the Cascades, including the western slopes.
Because of this rainfall and mild June temperatures (no major heatwaves), the fuel humidity around the region is not particularly low and, in fact, wetter than last year at this time. And by the way, last year was a year of very few wildfires.
To illustrate that the situation is better than last year, below is a 10-hour fuel moisture content in Leecher, WA, not too far from Omak (2023 at top, 2022 at bottom)
So we’ve had a normal to below-normal wildfire year so far, no droughts east of Washington and Oregon, and not too dry fuel humidity due to heavy rain east of the Cascades and No major heat waves.
Doesn’t sound like a seriously threatening wildfire situation at this point, does it?
National epicenter of wildfire disaster?
Look forward
Recently, West Coast weather has been dominated by depressions/low pressure in the Southwest US, bringing cool and wet conditions to California and more thunderstorms east of the Cascades (see upper-level map ( pressure of 500 hPa, approximately 18000 ft) light for illustration.Blue indicates lower than normal pressure/altitude
But this week there will be big volatility, a weak high pressure trough moving over the west coast (last Friday forecast see below)
This pattern will be in place for much of the next week. We will warm up a bit and thunderstorms will subside east of the Cascades. As shown below, western Washington will be warmer in the mid-80s early next week.
This is not a situation that creates a large heat wave or strong wind. Surface fuel will deplete more and some grass fires may occur.
Crucially, many models predict a return of the West Coast bottom, which will deliver the conditions we enjoyed last week (see upper-level forecast for Saturday morning, August 8). July). Conditions are not favorable for the area fire.
The bottom line of all this? The current wildfire situation is quite typical and there is no reason to predict a particularly severe summer fire season in the Northwest. There will be forest fires, so people need to be careful.
And one more thing. The Seattle Times article said last year’s Bolt Fire was a “dress exercise” about the effects of climate change.
Simply wrong.
The wildfires in Western Washington are definitely related to the strong easterly (from the east) winds that occur in the (typically) dry late summer.
The latest research (including the one I have published) is that such winds will weaken under global warming. Also, let’s not forget that the Bolt Fire was caused by an illegal fire and burned down a previously cleared forest with a lot of debris lying on the forest floor.
