Weather model shows where California will burn

Weather model shows where California will burn

15 February 2010
Magazine issue 2747. Subscribe and get 4 free issues.

THIS year, southern California will burn - you can count on it. But we may now be able to predict which areas will be worst hit, thanks to this map. It was compiled by Max Moritz's team at the University of California, Berkeley, and is the first to take into account fire-friendly weather.

Wild fires cause millions of dollars of damage each year in California and elsewhere. Fire researchers typically identify risk areas by looking for flammable vegetation and features like canyons that can funnel fires. There is a third factor, however, that stokes many of the worst infernos: hot, dry winds, like the Santa Ana winds of southern California and the sirocco around the Mediterranean.

Moritz and his colleagues used a computer model of fine-scale weather patterns to predict temperature, wind speed and humidity at 6-kilometre intervals across southern California during Santa Ana wind events, then calculated the fire risk at each point. When they compared their map with historical fire records, the researchers found that the areas they had identified as being at high and low risk were equally as likely to burn, but the impact of fire was greatest in a high-risk area (Geophysical Review Letters, http://dx.doi.org/10.1029/2009GL041735">DOI: 10.1029/2009GL041735, http://europa.agu.org/?view=article&uri=/journals/gl/gl1004/2009GL041735/2009GL041735.xml">in press).

Moritz's map may help planners guide housing development away from the riskiest areas. The approach could also be used in other fire-prone regions like South Africa and western Australia, he says.