Santa Ana Winds
From October through February, Southern California must contend with troublesome northeasterly winds known as the Santa Ana’s. Named after the Santa Ana Canyon, these winds have many nicknames including the Santana’s, Red Wind, and Devil’s Breath. The Santa Ana’s form when a strong high-pressure system develops over the Great Basin and a low-pressure system forms off the Southern coast of California causing winds with speeds of 25 knots (28.8 mi) or higher (see Figure 1).When the Santa Ana’s are active, the coastal areas of Southern California experience an increase in temperature and a decrease in humidity levels. Though the air is relatively cool in the high desert at this time of year, when it rapidly descends through the mountain passes from the desert to the ocean, the air becomes compressed, increasing the temperature by 5ºF every 1,000 ft. In fact, Santa Ana’s can raise the air temperature by 30ºC (54ºF) and temperatures near the coast can exceed 40ºC (104ºF). Normally, the low temperature between October and February in the Southern California region is 51ºF and the average high temperature is 68.1ºF and the average humidity level ranges between 76% in the morning and 56%. However, the Santa Ana’s typically cause the humidity levels to drop below 25%.
The main hazard associated with the Santa Ana’s is the spread of wildfires. Because of the highly flammable and dry nature of the native plant life in Southern California, the Santa Ana’s can take a single spark and transform it into an uncontrollable firestorm. One of the most notable wildfires associated with the
Santa Ana’s occurred in 1961 when a wildfire spread through Bel Air, destroying almost 500 homes. In 1991, 24 people died in a wildfire as over 1,000 homes were destroyed in the Oakland Hills, near San Francisco Bay. In 1993, more than 1,000 homes were destroyed when fires spread from Laguana Beach to Malibu and Santa Barbara. In October 2003, wildfires again spread across Southern California (see Figure 2). By 27 October, over 825 homes were destroyed and over 330,000 acres had burned.Wildfires are not the only problem associated with the Santa Ana winds. As the Santa Ana’s blow through the desert, they pick up dust and sand, transporting these air-borne particles to the coast (see Figure 3). The strong Santa Ana winds cause trouble for boaters by creating conditions that result in small craft advisories (wind to 38 mph) or gale advisories (winds from 39-54 mph). Finally, hazardous coastal fog develops as the Santa Ana’s end.
References and LinksBooks
Aguado, E. and J. E. Burt. 2001. Understanding the Weather and Climate. second edition. Prentice Hall: Upper Saddle River, NJ.
Ahrens, C. D. 2001. Essentials of Meteorology: An Invitation to the Atmosphere. Third edition. Brooks/Cole, Thomson Learning: Australia.Websites
Davis, G., N. D. Mary, & R. Tsuneyoshi. State of California: The Resources Agency: Department of Boating and Waterways. Safe Boating Hints for the Southern Coast. http://dbw.ca.gov/Pubs/Scoast/SouthCoast.pdf
Midwestern Regional Climate Center. http://mcc.sws.uiuc.edu/
Santa Ana. http://meteora.ucsd.edu/cap/santa_ana.html
-Figure 1
-Figure 3
Santa Ana Winds. http://nimbo.wrh.noaa.gov/Sandiego/snawind.html
The Santa Ana Winds. http://www.atmos.ucla.edu/~fovell/ASother/mm5/SantaAna/winds.html
EnvirocastTM TV for Monday October 27, 2003 Fires in Southern California. http://www.stormcenter.com/media/031027/
-Figure 2
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Created by: Scott Schoefernacker
Last Updated: December 2003