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SANTA ANA WINDS

SANTA ANA WINDS. SANTA ANA WINDS. LOCATION DESCRIPTION DEVELOPMENT SPEED TEMPERATURE DURATION CONSEQUENCES. LOCATION. The Santa Ana Winds occur below the passes and canyons of the coastal ranges of Southern California and in the Los Angeles Basin.

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SANTA ANA WINDS

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  1. SANTA ANA WINDS

  2. SANTA ANA WINDS • LOCATION • DESCRIPTION • DEVELOPMENT • SPEED • TEMPERATURE • DURATION • CONSEQUENCES

  3. LOCATION • The Santa Ana Winds occur below the passes and canyons of the coastal ranges of Southern California and in the Los Angeles Basin. • The winds blow with exceptional speed in the Santa Ana canyon; the canyon from which it derives its name.

  4. SANTA ANA MOUNTAINS

  5. DESCRIPTION • The Santa Ana winds are hot and dry, and they blow from east to west instead of the normal west to east. • Bring beautiful clear skies, and the presence of smog is limited.

  6. DURATION • Winds commonly occur between October and February with December having the highest frequency of events. • Summer events are rare.

  7. DEVELOPMENT • The winds develop when a high pressure system builds over the Rocky Mountains (Nevada, Utah). At the same time there exists a low pressure system over Southern California. • The regions to the west of a high-pressure center have southerly winds bringing in relatively warm air.

  8. DEVELOPMENT • High pressure systems usually form where the air converges aloft. As the air converges in the upper-levels of the atmosphere, it forms an area of higher pressure and is forced to sink. • Winds blow from high pressure to low pressure.

  9. DEVELOPMENT • Clockwise circulation around the center of this high pressure area forces air downslope from the high plateau. • The air warms and is compressed as it descends toward the California coast at the rate of 5 degrees Fahrenheit per 1000 feet due to adiabatic warming.

  10. SPEED • The winds are usually gusty and can change direction quickly. • Wind speeds are enhanced as the flow channels through the mountain passes. • Wind speeds are typically north to east at 40 mph through and below passes, and canyons with gusts to 57 mph. Gusts can be greater than 115 mph in favored areas.

  11. SANTA ANA WIND LOG • 10/17/99 - First Santa Ana wind event of the season. Wind speeds of 38 MPH. • 11/22/99 - Winds reached 45 MPH. • 12/19/99 - December has the highest frequency of events. Winds speeds of 48 MPH. • 1/5/00 - Winds gusted to 50 MPH and remained strong all night. End of Santa Ana wind season.

  12. TEMPERATURE • The sinking air can warm by 54 degrees Fahrenheit or more and attain temperatures in excess of 104 degrees Fahrenheit near the coast. • Santa Ana Winds are not warm because they pass over hot desert surfaces, it is compression that causes their high temperature.

  13. CONSEQUENCES • Power outages. • The most notable consequence of Santa Ana Winds is fires, especially wildfires. • Although Santa Ana Winds do not usually initiate a fire, the spreading caused by the winds prevents it from being controlled and amplifies the damage.

  14. CALIFORNIA FIRES • Also, the winds are dry to begin with. Since no moisture is added, the relative humidity drops, often into the single digits. The extremely low humidity helps dry out vegetation, making it a better fuel for fires.

  15. DAMAGES • In 1996 Santa Ana winds whipped up fires in Malibu and Carlsbad. • The fires destroyed 140 homes, forced thousands to evacuate, and scorched more than 20,000 acres of brush land.

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