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Prescribed Fire In Yosemite National Park Out of Control, More Than 20 Times Its Intended Size


A full-on assault is under way on a fire in Yosemite National Park that started out to be a prescribed burn of 90 acres but now has charred more than 2,200 acres.

The Big Meadow Fire was set Wednesday on the southwestern edge of the park but it quickly jumped the designated perimeter lines. More than 500 firefighters, backed by three helicopters, four air tankers, and 24 engines are battling the flames.

The fire has forced the closure of the Big Oak Flat Road (Highway 120) from Crane Flat to the junction of the El Portal Road (Highway 140). While no homes have been lost, residents of Foresta and campers in the Crane Flat Campground were moved and there continues to be no access to these areas. Highway 120 in the park will remain closed until further notice.

The fire is currently 10% contained.


Stuff happens. Even with the greatest of care Mother Nature can pull a surprise on you. Perscribed burning is a great resource management tool, but it is not 100% perfect. Hopefully no homes or other private structures will be lost. The forests will recover given time and wildlife habitat will likely be much improved.

Perhaps a fire ecologist can explain: Why wasn't this prescribed burn done in early fall when low humidity takes place and cool temperatures are most likely to prevail and usually after a light rain?

"Stuff Happens"? Please don't get carried away with your empathy ! :+))

I'm neither a fire ecologist nor a fire manager, but I work with both in vegetation dynamics. The prescriptions or rules for controlled burns are very restrictive. There are several reasons why that fire might have been planned for late August, not October:

1: "Natural" burn season. My best guess for that part of the country is that non-anthropogenic ignitions would have been early and late summer dry lightning. Burns in different seasons differentially affect species composition; winter burns versus growing season burns directly affect different understory species (native species are likely to be able to resprout from natural season burns the evolved with). The targeted area could have been a burn-out of shrubs and seedling encroaching on meadows. The species targeted by the burn might have been mostly dormant with their resources belowground by October, and thus could easily resprout next spring after a fall-winter fire.

2: The limited window of burn conditions requires burning any time throughout the year that the prescription is met. The temperatures and humidity and fuel moisture all must be within bounds, and the wind cannot be too high (too hard to control) or too low or in the wrong direction (air quality restrictions on smoke), especially near highways and populated areas. [This might be the case for this particular burn, as the location is just below the mouth of Yosemite Valley and thus within a few miles of all 3 roads into the valley, and prevailing winds from the west would take the smoke both across the roads (a safety issue) and into the valley where it would be trapped (a health and visitor experience issue).] A need for more burning than there are days to burn is quite common in the southeast, where vegetation that should burn at low intensity every 5-10 years can't be burned fast enough, and FS burns year round.

3: Availability of firefighting resources in case it jumps a line. September and October are peak wildfire season in much of California, especially the chaparral in Southern California where densely populated areas intertwine with fire-dependent vegetation. Earlier in the summer is peak fire season in the northwest and northern Rockies.

The national fire situation report from 5:30am MDT for the Meadow Fire: "Brush. Active fire behavior with sustained crown runs and spotting. Residences threatened. Road closures and evacuations in effect." I'll post a copy of the NPS fire news item when it becomes available, as it is likely to give information on the original prescription.

I have been on several prescribed burns in the Sierra's and they routinely get bumped becuase of air quality restrictions. Not sure if that is the case here, but it is common.

Tomp, thanks for your in put and it does shed a better light on the dynamics of a prescribe burn. With wild fires in California as they are today, I thought a prescribed burn would be pretty least wait until late fall. But, your comments are most informative and does explain some the vegetation mechanics behind a prescribe burn.

Empathy for what, d-2? Nothing has been lost yet. Sounds like nothing is even in particular danger. And there sure is no need for empathy towards the trees...they need it.

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