Wednesday, October 24, 2007

The West On Fire

Have you heard about the wildfires blazing in southern California? A record 500,000 people have evacuated their homes in the San Diego area, and President Bush has declared the situation a major disaster.

So far, the area these fire have burned is about 12% greater than the record-breaking Milford Flat Fire, which made news as it blazed across south-central Utah this summer. While that fire closed large stretches of I-15 and burned several buildings, it didn't even come close to doing as much damage as the San Diego fires have caused so far. What's the difference?

There are two main ways in which the California fires are different from even the biggest fires in Utah: people and wind.

Imagine what the Milford Flat fire might have been like if the whole population of Utah lived in that area! When fires travel into human-occupied areas they can cause big problems as they destroy property, force evacuations, and sometimes take lives. The more people around, the more problems. San Diego County, where the majority of the California fires are clustered right now, has a population of almost 3 million people. By contrast, the entire state of Utah has a population of about 2.5 million. The dense population in the San Diego area is part of why the fires are causing so much disruption.

Utah may have its share of blustery days, but they're nothing compared to the Santa Ana winds racing across southern California. According to a UCLA meteorologist, "Santa Ana winds are dry and warm (often hot) winds in the Southern California area that blow in from the desert." These winds develop from September through March, and usually flow fast and furious for a few days at a time. They help fires start by drying out the surrounding vegetation, and once a fire is going, they can fan the flames and help it spread.

Studying the Science
Each major wildfire is unique, of course, and individual fires can be hard to predict. Researchers all over, including some here at the University of Utah, are trying to find ways both to model what happens once fires start burning, and to anticipate when they're likely to start. In the meantime, we'll keep facing this force of nature as it comes.

Should people be allowed to live in areas prone to wildfires? What experiences with fire have you had? Click "comments" below and let us know!