The Santa Ana and Wildfires

"Disaster: Conditions may worsen tonight, and firefighters brace for return of Santa Anas on Saturday. President declares state of emergency in three counties." So writes the Los Angeles Times on Thursday, October 24, 1996.

What's the connection between the Santa Ana and wildfires in the Pacific counties of Southern California?

A Santa Ana is a fierce, hot, dry, and dusty wind that blows from the east across the mountain passes of Southern California, especially those between the San Gabriel Mountains north of Los Angeles and the San Bernardino Mountains further east. As the wind descends through the narrow canyons and sweeps into the lower-elevation coastal areas, it speeds up and becomes warmer and drier. Wind speeds in excess of forty miles per hour are typical, and locally, wind gusts may reach 100 miles per hour. The wind dries everything in its way -- grasslands, brush, orange groves, forests, and suburbs.

The dryness and gusty nature of the Santa Ana create dangerous wildfire conditions. This is especially true in late fall due to the accumulated dryness of the land from the summer months. A casually tossed-away match or cigarette, an unattended campfire, or lightning may set off a fire that can quickly flare out of control. The result may be the destruction of homes, schools, and businesses, the devastation of the vegetation of tens of thousands of acres, the closing of highways, and the loss of life. Those kinds of tragedies have been experienced by the people of Los Angeles, Orange, and San Diego Counties during the past weeks, and made them eligible for federal disaster relief.

More Hot Stuff

For a more detailed description of the cause of a Santa Ana wind and a fire weather index map of the Great Basin High during Santa Ana conditions, go to a Web site of the Climate Research Division of the University of California, San Diego:

http://meteora.ucsd.edu/~chen/Santa_ana/Santa_ana.html

You can access experimental fire weather forecasts based on a modeling system from the National Centers for Environmental Prediction (NCEP) at:

http://meteora.ucsd.edu/ecpc/globaltoregional/FWI/fwi.html

NASA, the Bureau of Land Management (BLM), the USDA Forest Service, and the Nevada Division of Forestry are evaluating an electronic Advanced Navigation Display System (ANDS) developed by NASA's Ames Research Center (ARC) in Mountain View, CA, to aid aerial firefighters in their communications and operations. For more information, go to NASA press release 96-151 of July 30, 1996:

ftp://ftp.hq.nasa.gov/pub/pao/pressrel/1996/96-151.txt

NASA's ARC and the USDA Forest Service have built a low-cost, airborne scanning instrument for monitoring fires, measuring fire intensity, and determining a fire's impact on the ecosystem. The instrument, which is called the Airborne Infrared Disaster Assessment System (AIRDAS), can also be used in monitoring disasters other than fires. For more information, go to:

http://geo.arc.nasa.gov/sge/brass/Brass.AIRDAS.html

To learn about current wildfires and wildfire conditions throughout the US, go to the Wildland Fire Assessment System of the USDA Forest Service. Click on "Maps & Links," and you'll get to maps that are updated daily and graphically show fire danger, winds, precipitation, temperature, relative humidity, and other parameters relevant to wildfire hazards:

http://www.fs.fed.us/land/wfas/welcome.htm

To learn how you can lessen the risk of wildfire loss for yourself, your family, and your neighbors, go to the Firewise homepage, which is sponsored by the USDA Forest Service, the Department of the Interior, the National Association of State Foresters, the National Fire Protection Association, and the US Fire Administration:

http://www.firewise.org/

Check out other observations in the Observation of the Week Archive.