June is the beginning of the grass wildfire season over the lowlands of eastern Washington.
By June, the extensive grass and range vegetation of the Columbia Basin has dried out and "seasoned" sufficiently to burn. Also in June, strong westerly (from the west) winds can develop as weak Pacific weather systems move through.
Dry range vegetation, strong winds, and an ignition source are the ingredients for a large, fast-spreading fire.
All of this has happened over the past few days, producing several significant grass and range fires, including the one at Juniper Dunes (13,000 acres!).
The map below shows some of the recent fires.
Here is a satellite image of the Juniper Dune fire from two days ago. Pretty impressive looking.
The grass fires are now history, but you can see the burned (brown) areas in today's visible satellite image.
So why the fires?
The fuel moisture of small dead fuels was under 11% and thus flammable (see below).
Light dead fuels, such as grasses and small-diameter debris, can dry out within hours under the right conditions.
And then there are the winds resulting from the passage of a weak trough aloft. To illustrate, here are the gusts yesterday---at several locations they exceeded 50 mph!
The strong winds are critical for the rapid expansion of such prairie fires.
It appears that these fires were initiated by careless humans, which is true of most eastern Washington grass fires.
The "Upriver Fire", six miles NE of Spokane, apparently human caused, has burned through grass and trees. Center of the area is about here: 47.698366, -117.312774
ReplyDeleteWhile Cliff writes of grass and range vegetation -- the current issue -- there is an introduced plant that is just now flowering along creeks and roadside ditches. Locals call it Autumn Clematis, while gardeners embellish with "Sweet" as a prefix. {Clematis terniflora}
This is a vine that can grow to 30 feet. It grows along the ground, on fences, up trees. Like Kudzu, Clematis densely climbs over other plants and trees and grows so rapidly that it smothers and kills them by blocking most of the sunlight and taking root space and moisture. Impenetrable masses of "fuel" accumulate. In Kittitas County the plants are currently blooming, and the new growth is lush and pretty, and hiding the danger underneath.
If there's anything good about global warming it seems like it may be less June Gloom. At a price, of course...
ReplyDeleteThis June has seemed moderately warmer than typical, with the absence of day after day of gloom like we see some years. In the south sound, we’ve already seen several days with highs over 80°F on the books, with at least a few more to come before the month’s close.
ReplyDeleteI’d be curious to see a plot of observed temps vs. normal at KOLM, after this month is done.
https://www.weather.gov/wrh/Climate?wfo=sew&tab=cliplot&sid=OLMthr&view=monthly&month=2026-06
DeleteI haven't seen any June gloom worth riding home about
ReplyDelete