Lightning found to have ignited Oregon's mammoth Bootleg fire
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[July 22, 2021]
By Steve Gorman
(Reuters) - A destructive Oregon wildfire
that ranks as the largest among dozens raging across the drought-parched
Western United States in recent weeks was ignited by lightning but
smoldered for days before it was detected, forest officials said on
Wednesday.
The origin of the so-called Bootleg fire, which was first reported July
6 in the Fremont-Winema National Forest some 250 miles south of
Portland, came to light as ground crews made increasing headway in
curtailing the blaze.
Strike teams were taking advantage of calmer winds, cooler temperatures
and slightly higher humidity over the past two days to extend and
bolster containment lines around the fire's periphery, incident
commanders reported in their latest summary.
Although the blaze continued to expand, its growth was stunted as flames
advanced into an old fire-scarred area with less vegetation available to
burn, officials said.
As of Wednesday, the Bootleg had charred 395,463 acres (160,038
hectares) of tinder-dry brush and timber - an area well over half as big
as Rhode Island. At that size, the fire was just a few hundred acres
away from becoming Oregon's third largest on record since 1900.
It also has blackened far more acreage than any one of about 80 major
active wildfires currently reported in 13 Western states this week.
Those fires, along with the Bootleg, have collectively scorched more
than 1.3 million acres (526,000 hectares) in an unusually heavy start to
the Western fire season that experts say is symptomatic of climate
change.
Although hot, dry, windy weather has played a key role in stoking this
summer's spate of wildfires, many were ignited by lightning strikes.
The cause of the Bootleg fire had been listed as under investigation
until Wednesday, when officials revealed its ironically humble
beginnings.
Forest Service investigators determined it was
sparked by a lightning strike from a storm that was previously known to
have ignited a smaller, nearby fire that was extinguished on June 30,
Oregon Forestry Department spokesman Marcus Kauffman told Reuters.
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A destructive Oregon wildfire that ranks as the largest among dozens
raging across the drought-parched Western United States in recent
weeks was ignited by lightning but smoldered for days before it was
detected, forest officials said on Wednesday.
Unknown to authorities at the time, an invisible "holdover" fire
that would ultimately grow into the Bootleg smoldered unnoticed -
apparently concealed beneath mounds of pine needles, cones and duff
on the forest floor - before it was detected and reported on July 6,
Kauffman said.
Although no fatalities or serious injuries have been reported, the
Bootleg has destroyed at least 67 homes and more than 100
outbuildings and other structures.
Some 3,400 dwellings remained listed as threatened, many under
evacuation orders or notices for residents to be ready to flee at a
moment's notice.
An army of some 2,200 personnel, backed by water-dropping
helicopters and airplane tankers, has managed to carve containment
lines around nearly a third of the fire's still-growing perimeter,
officials said on Wednesday.
The Bootleg fire is so large that it has at times generated its own
weather - towering pyrocumulus clouds of condensed moisture sucked
up through the fire's smoke column from burned vegetation and the
surrounding air. These clouds can spawn lightning storms and high
winds capable igniting new fires and spreading the flames.
(Reporting by Steve Gorman in Los Angeles; Editing by Leslie Adler)
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