Tornado-like updrafts of flying debris pose danger for air tankers fighting Washburn fire
SAN FRANCISCO (KPIX) -- Burning dangerously close to the famed Mariposa Grove, the Washburn Fire isn't just causing trouble on the ground, but in the skies as well.
A radio dispatch from a Canadian based air attack tanker working the Washburn Fire described it.
"So a branch went right over the top of us. Pretty good size. So, if we keep seeing that, uh, we might have to knock it off. I don't want to take a chance of busting window or an airplane or hurting an aircraft for this," said the dispatcher.
It's a phenomenon called updrafting, with internal fire weather causing winds strong enough to toss debris in the air - think of the famous flying cow scene from the movie "Twister" - but in a fire.
"The heat of the fire generates real strong updrafts and those strong air updrafts move vertically into the atmosphere and that's what's carrying the debris and potentially pieces of bark, tree limbs and such - but it's not long lived, it's short lived pulses," says Prof. Craig Clements of San Jose State.
Clements is a professor of meteorology and the director of the California Wildfire Research Center.
"To hear about these branches being lofted, that's kind of unique," Clements said.
The force of the updrafts is intense. In 2016, a research plane flew through a pyrocumulonimbus cloud in Idaho.
"Measure updrafts of a 120 miles an hour - those winds can easily lift big particles and things into the upper part of the plume," said Clements.
As for the giant sequoias, they're getting special protection in the form of fire blankets around the base and humidity increasing sprinklers.
"I'm standing right in front of the grizzly giant - arguably one of the most famous trees on earth and we've got a sprinkler system set up around it and we're trying to give it some preventative first aid," said one Cal Fire firefighter.
Giant sequoias need fire and the work being done can assure the Washburn Fire remains therapeutic, not catastrophic to the grand trees.
"What they're doing with sprinklers to protect a lot of those trees is great. This is probably going to be a good thing - if the fire remains at low intensity burning through that forest - so it could be a positive effect for that forest," Clements said.