Santa Ana winds

This article is about the seasonal strong winds in Southern California. For other uses, see Santa Ana winds (disambiguation).

The Santa Ana winds sweep down from the deserts and across coastal Southern California, pushing dust and smoke from wildfires far out over the Pacific Ocean. Los Angeles is in the upper left of this image, while San Diego is near the center.

The Santa Ana winds, also sometimes called the devil winds,[1][2] are strong, extremely dry downslope winds that originate inland and affect coastal Southern California and northern Baja California. They originate from cool, dry high-pressure air masses in the Great Basin.

Santa Ana winds are known for the hot, dry weather that they bring in autumn (often the hottest of the year), but they can also arise at other times of the year.[3] They often bring the lowest relative humidities of the year to coastal Southern California, and "beautifully clear skies".[4] These low humidities, combined with the warm, compressionally-heated air mass, plus high wind speeds, create critical fire weather conditions and fan destructive wildfires.[4]

Typically, about 10 to 25 Santa Ana wind events occur annually.[5] A Santa Ana can blow from one to seven days, with an average wind event lasting three days.[6] The longest recorded Santa Ana event was a 14-day wind in November 1957.[5] Damage from high winds is most common along the Santa Ana River basin in Orange County, the Santa Clara River basin in Ventura and Los Angeles County, through Newhall Pass into the San Fernando Valley of Los Angeles County, and through the Cajon Pass into San Bernardino County near San Bernardino, Fontana, and Chino.[6]

Description

Meteorology

The Santa Anas are katabatic winds (Greek for "flowing downhill") arising in higher altitudes and blowing down towards sea level.[7] The National Weather Service defines Santa Ana winds as "a weather condition [in southern California] in which strong, hot, dust-bearing winds descend to the Pacific Coast around Los Angeles from inland desert regions".[8]

This map illustration shows a characteristic high-pressure area centered over the Great Basin, with the clockwise anticyclone wind flow out of the high-pressure center giving rise to a Santa Ana wind event as the airmass flows through the passes and canyons of Southern California, manifesting as a dry northeasterly wind.

Santa Ana winds originate from high-pressure airmasses over the Great Basin and upper Mojave Desert. Any low-pressure area over the Pacific Ocean, off the coast of California, can change the stability of the Great Basin High, causing a pressure gradient that turns the synoptic scale winds southward down the eastern side of the Sierra Nevada and into the Southern California region.[9] According to one meteorology journal, "a popular rule of thumb used by forecasters is to measure the difference in pressure between the Los Angeles International Airport and Las Vegas; a difference of 9 millibars (0.27 inches of mercury) is enough to support a Santa Ana event."[5] Dry air flows outward in a clockwise spiral from the high pressure center. This dry airmass sweeps across the deserts of eastern California toward the coast, and encounters the towering Transverse Ranges, which separate coastal Southern California from the deserts.[10] The airmass, flowing from high pressure in the Great Basin to a low pressure center off the coast, takes the path of least resistance by channeling through the mountain passes to the lower coastal elevations, as the low pressure area off the coast pulls the airmass offshore.[11]

Mountain passes which channel these winds include the Soledad Pass, the Cajon Pass, and the San Gorgonio Pass, all well known for exaggerating Santa Anas as they are funneled through.[5] As the wind narrows and is compressed into the passes its velocity increases dramatically, often to near-gale force or above. At the same time, as the air descends from higher elevation to lower, the temperature and barometric pressure increase adiabatically, warming about 5 °F for each 1,000 feet it descends (1 °C for each 100 m).[12] Relative humidity decreases with the increasing temperature. The air has already been dried by orographic lift before reaching the Great Basin, as well as by subsidence from the upper atmosphere, so this additional warming often causes relative humidity to fall below 10 percent.[13]

The end result is a strong, warm, and very dry wind blowing out of the bottom of mountain passes into the valleys and coastal plain. These warm, dry winds, which can easily exceed 40 miles per hour (64 km/h),[citation needed] can severely exacerbate brush or forest fires, especially under drought conditions.

During Santa Ana conditions it is typically hotter along the coast than in the deserts,[14] with the Southern California coastal region reaching some of its highest annual temperatures in autumn rather than summer. Frigid, dry arctic air from Canada tends to create the most intense Santa Ana winds.[15]

QuikSCAT image showing the speed of the Santa Ana winds (m/s)

While the Santa Anas are katabatic, they are not Föhn winds. These result from precipitation on the windward side of a mountain range which releases latent heat into the atmosphere which is then warmer on the leeward side (e.g., the Chinook or the original Föhn).

If the Santa Anas are strong, the usual day-time sea breeze may not arise, or develop weak later in the day because the strong offshore desert winds oppose the on-shore sea breeze. At night, the Santa Ana Winds merge with the land breeze blowing from land to sea and strengthen because the inland desert cools more than the ocean due to differences in the heat capacity and because there is no competing sea breeze.[13][16]

Santa Ana winds are associated in the public mind with dry hot weather, but cold Santa Anas not only exist but have a strong correlation with the highest "regionally averaged" wind speeds.[17]

Regional impacts

The Thomas Fire and two other fires burn out of control near Ventura in December 2017, with a strong Santa Ana wind driving the flames toward the coast and blowing the smoke offshore.

Santa Ana winds often bring the lowest relative humidities of the year to coastal Southern California. These low humidities, combined with the warm, compressionally-heated air mass, plus the high wind speeds, create critical fire weather conditions. The combination of wind, heat, and dryness accompanying the Santa Ana winds turns the chaparral into explosive fuel feeding the infamous wildfires for which the region is known.

Although the winds often have a destructive nature, they have some benefits as well. They cause cold water to rise from below the surface layer of the ocean, bringing with it many nutrients that ultimately benefit local fisheries. As the winds blow over the ocean, sea surface temperatures drop about 4°C (7°F), indicating the upwelling. Chlorophyll concentrations in the surface water go from negligible, in the absence of winds, to very active at more than 1.5 milligrams per cubic meter in the presence of the winds.[5]

Local maritime impacts

During the Santa Ana winds, large ocean waves can develop. These waves come from a northeasterly direction toward the normally sheltered sides of the Channel Islands, including commonly visited Catalina and Santa Cruz islands. Normally well-sheltered harbors and anchorages such as Avalon and Two Harbors can develop high surf and strong winds that can tear boats from their moorings. During Santa Ana conditions, it is advised that boaters moor on the Southern side of affected islands or return to the mainland.[18]

Santa Ana fog

A Santa Ana fog is a derivative phenomenon in which a ground fog settles in coastal Southern California at the end of a Santa Ana wind episode. When Santa Ana conditions prevail, with winds in the lower two to three kilometers (1.25-1.8 miles) of the atmosphere from the north through east, the air over the coastal basin is extremely dry, and this dry air extends out over offshore waters of the Pacific Ocean. When the Santa Ana winds cease, the cool and moist marine layer may re-form rapidly over the ocean if conditions are right. The air in the marine layer becomes very moist and very low clouds or fog occurs.[19][20] If wind gradients turn on-shore with enough strength, this sea fog is blown onto the coastal areas. This marks a sudden and surprising transition from the hot, dry Santa Ana conditions to cool, moist, and gray marine weather, as the Santa Ana fog can blow onshore and envelop cities in as quickly as fifteen minutes. However, a true Santa Ana fog is rare, because it requires conditions conducive to rapid re-forming of the marine layer, plus a rapid and strong reversal in wind gradients from off-shore to on-shore winds. More often, the high pressure system over the Great Basin, which caused the Santa Ana conditions in the first place, is slow to weaken or move east across the United States. In this more usual case, the Santa Ana winds cease, but warm, dry conditions under a stationary air mass continue for days or even weeks after the Santa Ana wind event ends.

A related phenomenon occurs when the Santa Ana condition is present but weak, allowing hot dry air to accumulate in the inland valleys that may not push all the way to sea level. Under these conditions auto commuters can drive from the San Fernando Valley where conditions are sunny and warm, over the low Santa Monica Mountains, to plunge into the cool cloudy air, low clouds, and fog characteristic of the marine air mass. This and the "Santa Ana fog" above constitute examples of an air inversion.

Sundowner winds

Main article: Sundowner (wind)

The similar winds in the Santa Barbara and Goleta area occur most frequently in the late spring to early summer, and are strongest at sunset, or "sundown"; hence their name: sundowner. Because high pressure areas usually migrate east, changing the pressure gradient in Southern California to the northeast, it is common for "sundowner" wind events to precede Santa Ana events by a day or two.[21]

Historical impact

Hygrometer showing low humidity during a Santa Ana wind event

The Santa Ana winds and the accompanying raging wildfires have been a part of the ecosystem of the Los Angeles Basin for over 5,000 years, dating back to the earliest habitation of the region by the Tongva and Tataviam peoples.[22] The Santa Ana winds have been recognized and reported in English-language records as a weather phenomenon in Southern California since at least the mid-nineteenth century.[1] During the Mexican–American War, Commodore Robert Stockton reported that a "strange, dust-laden windstorm" arrived in the night while his troops were marching south through California in January 1847.[5] Various episodes of hot, dry winds have been described over this history as dust storms, hurricane-force winds, and violent north-easters, damaging houses and destroying fruit orchards. Newspaper archives have many photographs of regional damage dating back to the beginnings of news reporting in Los Angeles. When the Los Angeles Basin was primarily an agricultural region, the winds were feared particularly by farmers for their potential to destroy crops.[1]

In early December 2011, the Santa Ana winds were the strongest yet recorded. An atmospheric set-up occurred that allowed the towns of Pasadena and Altadena in the San Gabriel Valley to get whipped by sustained winds at 97 mph (156 km/h), and gusts up to 167 mph (269 km/h).[23] The winds toppled thousands of trees, knocking out power for over a week. Schools were closed, and a "state of emergency" was declared. The winds grounded planes at LAX, destroyed homes, and were even strong enough to snap a concrete stop light from its foundation.[24] The winds also ripped through Mammoth Mountain and parts of Utah. Mammoth Mountain experienced a near-record wind gust of 175 mph (282 km/h), on December 1, 2011.[23]

Wildfires

Main article: California wildfires

Because they are simultaneous "gusty" and "desiccating," the Santa Ana winds are highly associated with regional wildfire danger.[25]

The winds have been implicated in some of the area's (and even the state's) largest and deadliest wildfires, including the Thomas Fire, and Cedar Fire, as well as the Laguna Fire, Old Fire, Esperanza Fire, and the Witch Creek Fire. Other major wildfires fueled by Santa Ana winds include:

Health effects

The winds carry Coccidioides immitis and Coccidioides posadasii spores into nonendemic areas,[26][27] a pathogenic fungus that causes Coccidioidomycosis ("Valley Fever"). Symptomatic infection (40 percent of cases) usually presents as an influenza-like illness with fever, cough, headaches, rash, and myalgia (muscle pain).[28] Serious complications include severe pneumonia, lung nodules, and disseminated disease, where the fungus spreads throughout the body. The disseminated form of Coccidioidomycosis can devastate the body, causing skin ulcers, abscesses, bone lesions, severe joint pain, heart inflammation, urinary tract problems, meningitis, and often death.[29]

Name etymology

The best-accepted explanation for the name Santa Ana winds is that it is derived from the Santa Ana Canyon in Orange County, one of the many locations where the winds blow intensely.[1][7][5] Newspaper references to the name Santa Ana winds appear as far back as 1882.[13] Per the Riverside Press-Enterprise in 2020:[30]

According to research done by Orange County historian Chris Jepsen, the first reported reference to that term comes to us in 1871 from the Anaheim Gazette. To anyone in what would become Orange County at the time, the winds seem to come out of Santa Ana Canyon, hence the name. However, having Santa Ana winds named for their city did not please the members of the Chamber of Commerce in the city of Santa Ana, and they fought for years to get the name changed.

The name Santa Ana wind became nationally known following a sensationalized 1901 wire story about wind damage.[5]

One narrative claimed that the term Santa Ana wind derives from a Native American phrase for "devil wind" that was then altered by Californios into the form "Satanás" (meaning Satan), and then still later corrupted into "Santa Ana". However, an authority on local Native American languages claims this supposed Indigenous term "Santana" never existed.[7] No evidence has ever emerged to support this explanation and it is likely a false etymology.[6]

In 1933, Father John O'Connell of Mission San Juan Capistrano reported that Don Jesus Aguilar, born 1855 at Capistrano, said that in his day the winds had been called el viento del norte.[6]

Santa Ana winds are widely believed to affect people's moods and behavior.[31][32][33] The Santa Ana winds are commonly portrayed in fiction as being responsible for a tense, uneasy, wrathful mood among Angelenos.[1][34][35] As The New York Times put it in 2003, "a dry, hot Santa Ana often symbolizes an unnamable menace lying just beneath the sun-shot surface of California life."[36] According to the Pasadena Public Library [Wikidata] book blog, the winds notably appear in Richard Henry Dana's Two Years Before the Mast, the Philip Marlowe story "Red Wind" by Raymond Chandler, three essays by Joan Didion about Los Angeles, ("Los Angeles Notebook" and "Some Dreamers of the Golden Dream", both included in her 1968 book Slouching Towards Bethlehem, and "Fire Season", included in her 1992 book After Henry), The Husband by Dean Koontz, White Oleander by Janet Fitch, and Less than Zero by Bret Easton Ellis.[34] In Thomas Pynchon's 2009 "California novel" Inherent Vice the winds make an appearance and, per one scholar, "the obligatory noir description of their effects appears on page 98."[37]

Los Angeles Times columnist David L. Ulin commented, "...for writers such as Didion and Chandler, the Santa Ana is an emblem of disruption because, for them, Los Angeles is a disrupted world. We can take issue with that impression of the city; I sometimes do and sometimes don't. But when the Santa Ana starts to blow, I invariably grow edgy...unable, in the most concrete sense, to settle myself down."[35]

There was a desert wind blowing that night. It was one of those hot dry Santa Anas that come down through the mountain passes and curl your hair and make your nerves jump and your skin itch. On nights like that every booze party ends in a fight. Meek little wives feel the edge of the carving knife and study their husbands' necks. Anything can happen. You can even get a full glass of beer at a cocktail lounge.

— Raymond Chandler, "Red Wind" (1938)

The baby frets. The maid sulks. I rekindle a waning argument with the telephone company, then cut my losses and lie down, given over to whatever is in the air. To live with the Santa Ana is to accept, consciously or unconsciously, a deeply mechanistic view of human behavior. ... [T]he violence and the unpredictability of the Santa Ana affect the entire quality of life in Los Angeles, accentuate its impermanence, its unreliability. The wind shows us how close to the edge we are.

— Joan Didion, Slouching Towards Bethlehem (1968)

When the hills of Los Angeles are burning
Palm trees are candles in the murder winds
So many lives are on the breeze/ Even the stars are ill at ease
And Los Angeles is burning.

— Bad Religion, "Los Angeles Is Burning" (2004)

Some of this experienced mood shift is likely due to the increase of static electricity in dry conditions.[5] California folklore therefore credits the winds with "strange luminosity in the form of sparks and glows that accompany the winds" and an excess of "positive ions, disrupting health, well-being, and temperament."[5]

TV references

  • 9-1-1 episode "Red Flag"
  • In an episode of the drama Brothers and Sisters, a character who has recently returned to Los Angeles is forced to deal with her childhood fear of the Santa Ana winds as she navigates decisions in her romantic life.
  • The Santa Ana winds are personified in The CW musical series Crazy Ex-Girlfriend as a prankster narrator responsible for main characters and enemies Rebecca and Nathaniel kissing for the first time. A song titled "Santa Ana Winds" is sung in a doo-wop style reminiscent of Frankie Valli, educating the viewer on the winds itself.[38]
  • In an episode of The Rookie, the Santa Ana winds can be seen throughout the episode and are referenced by one of the main characters.

Movie and music references

Song references

See also

References

  1. ^ a b c d e Masters, Nathan (October 25, 2012). "SoCal's Devil Winds: The Santa Anas in Historical Photos and Literature". KCET. Archived from the original on October 29, 2012. Retrieved May 3, 2012. Scholars who have looked into the name's origins generally agree that it derives from Santa Ana Canyon, the portal where the Santa Ana River -- as well as a congested Riverside (CA-91) Freeway -- leaves Riverside County and enters Orange County. When the Santa Anas blow, winds can reach exceptional speeds in this narrow gap between the Puente Hills and Santa Ana Mountains.
  2. ^ Needham, John (March 12, 1988). "The Devil Winds Made Me Do It : Santa Anas Are Enough to Make Anyone's Hair Stand on End". Los Angeles Times. Archived from the original on April 29, 2014. Retrieved May 3, 2013.
  3. ^ Smith, Joshua Emerson (January 31, 2019). "Climate change should tamp down California's wildfire-fanning Santa Ana winds, study finds". Los Angeles Times. Retrieved February 3, 2019.
  4. ^ a b Pitt, Leonard (1997). Los Angeles A to Z: an encyclopedia of the city and county. Dale Pitt. Berkeley: University of California Press. p. 452. ISBN 0-520-20274-0. OCLC 35955263.
  5. ^ a b c d e f g h i j Vasquez, Tim (September 2008). "The Ill Wind That Blows: Southern California's Santa Ana Phenomenon". Weatherwise. 61 (5): 34–39. Bibcode:2008Weawi..61e..34V. doi:10.3200/WEWI.61.5.34-39. ISSN 0043-1672. S2CID 191474465.
  6. ^ a b c d e f Lessard, Arthur G. (April 1988). "The Santa Ana Wind of Southern California". Weatherwise. 41 (2): 100–104. Bibcode:1988Weawi..41b.100L. doi:10.1080/00431672.1988.9925254. ISSN 0043-1672.
  7. ^ a b c Fovell, Robert. "UCLA explains the naming of the Santa Ana winds". Orange County Register. Archived from the original on May 6, 2013. Retrieved May 3, 2012.
  8. ^ "Santa Ana Wind". NOAA's National Weather Service Glossary. NOAA National Weather Service. Retrieved January 25, 2023.
  9. ^ "Santa Ana". cnap.ucsd.edu. California Nevada Applications Program / California Climate Change Center. October 3, 2015. Archived from the original on October 25, 2015. Retrieved October 30, 2015.
  10. ^ Duginski, Paul (March 12, 2022). "Why it's been so warm and windy in Southern California this winter". Los Angeles Times. Retrieved May 10, 2022.
  11. ^ Lin II, Rong-Gong; Duginski, Paul (October 25, 2019). "Two destructive fires. Hundreds of miles apart. One culprit: Winds". Los Angeles Times. Retrieved October 25, 2019.
  12. ^ "What are the Santana or Santa Ana Winds?". Los Angeles Almanac. Archived from the original on November 2, 2015. Retrieved October 30, 2015.
  13. ^ a b c Fovell. "The Santa Ana Winds". UCLA. Archived from the original on February 1, 2014. Retrieved November 22, 2015.
  14. ^ "Santa Ana Winds - Wildfires". NOAA Watch All Hazards Monitor. NOAA National Weather Service. Archived from the original on March 10, 2011. Retrieved February 10, 2011.
  15. ^ Duginski, Paul (October 29, 2019). "Why Santa Ana winds later this week may be the strongest of the season thus far". Los Angeles Times. Retrieved October 29, 2019.
  16. ^ Leneman, Mike (2015). "Devil winds: Santa Ana Winds explained by one of us". The Mariner. Nov 2015 (153). Pat Reynolds: 8–9. Archived from the original on November 25, 2015. Retrieved November 22, 2015.
  17. ^ Gershunov, Alexander; Guzman Morales, Janin; Hatchett, Benjamin; Guirguis, Kristen; Aguilera, Rosana; Shulgina, Tamara; Abatzoglou, John T.; Cayan, Daniel; Pierce, David; Williams, Park; Small, Ivory; Clemesha, Rachel; Schwarz, Lara; Benmarhnia, Tarik; Tardy, Alex (October 2021). "Hot and cold flavors of southern California's Santa Ana winds: their causes, trends, and links with wildfire". Climate Dynamics. 57 (7–8): 2233–2248. Bibcode:2021ClDy...57.2233G. doi:10.1007/s00382-021-05802-z. ISSN 0930-7575. PMC 8165508. PMID 34092924.
  18. ^ Fagan, 2002, The Cruising Guide to Central and Southern California (International Marine)
  19. ^ Leipper, D. F., Fog development at San Diego, California, J. Mar. Research, 7, 337-346, 1948.
  20. ^ Leipper, D. F., Fog on the United States West Coast: a review. Bull. Amer. Meteor. Soc. 75, 229-240.
  21. ^ Ryan, G.; Burch, L. E. (1992). An analysis of sundowner winds: A California downslope wind event (Preprints). Sixth Conf. on Mountain Meteorology. Portland, OR: Amer. Meteor. Soc. pp. 64–67.
  22. ^ Rutten, Tim (October 15, 2000). "L.A., land of fire -- always". Los Angeles Times. Archived from the original on June 6, 2011. Retrieved May 3, 2013.
  23. ^ a b Christopher C. Burt (December 4, 2011). "Big Winds in the West, Possible Wind Gust Record in California". Weather Underground. Archived from the original on November 12, 2017. Retrieved January 24, 2017.
  24. ^ Medina, Jennifer (December 2, 2011). "Santa Ana Winds, Unusually Strong, Rattle More Than Nerves in California". The New York Times. Archived from the original on November 13, 2017. Retrieved February 28, 2017.
  25. ^ Null, Jan (July 4, 2015). "Weather and Wildland Fires: Firefighting in an Age of Droughts and Urban Sprawl". Weatherwise. 68 (4): 28–33. Bibcode:2015Weawi..68d..28N. doi:10.1080/00431672.2015.1045368. ISSN 0043-1672. S2CID 191207829.
  26. ^ "COCCIDIOIDOMYCOSIS" (PDF). Department of Public Health. Archived (PDF) from the original on February 3, 2014. Retrieved January 19, 2014.
  27. ^ Lawrence L. Schmelzer, M.P.H.; Irving R. Tabershaw, M.D., F.A.P.H.A. (1968). Exposure Factors In Occupational Coccidioidomycosis. McGraw Hill. p. 110.{{cite book}}: CS1 maint: multiple names: authors list (link)
  28. ^ Ryan, K.J.; Ray, C.G., eds. (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. pp. 680–83. ISBN 0-8385-8529-9.
  29. ^ "Coccidioidomycosis". Merck. Archived from the original on November 14, 2010. Retrieved January 19, 2014.
  30. ^ Lech, Steve (September 24, 2020). "How did the Santa Ana winds get their name?". Press Enterprise. Riverside, Calif. Retrieved March 15, 2023.
  31. ^ Studying the Dust Kicked up by the Santa Anas Archived 2016-03-04 at the Wayback Machine
  32. ^ Sullivan, Walter (October 6, 1981). "Ions Created by Winds May Prompt Changes in Emotional States". The New York Times.
  33. ^ NEEDHAM, JOHN (March 12, 1988). "The Devil Winds Made Me Do It: Santa Anas Are Enough to Make Anyone's Hair Stand on End". Los Angeles Times. Retrieved February 3, 2019.
  34. ^ a b PPL, Shauna (October 25, 2017). "On Edge: The Santa Ana Winds in Literature". Pasadena Public Library: On the Shelf. Retrieved March 15, 2023.
  35. ^ a b Ulin, David L. (May 14, 2014). "The Santa Ana winds and the literature of Los Angeles". Los Angeles Times. Retrieved March 15, 2023.
  36. ^ "PAGE TWO: THE READING FILE; In L.A., When the Wind Howls, So Do the Writers". The New York Times. November 2, 2003. ISSN 0362-4331. Retrieved March 15, 2023.
  37. ^ Miller, John (July 3, 2013). "Present Subjunctive: Pynchon's California Novels". Critique: Studies in Contemporary Fiction. 54 (3): 225–237. doi:10.1080/00111619.2011.578685. ISSN 0011-1619. S2CID 144183947.
  38. ^ Shoemaker, Allison (January 21, 2017). "The Santa Ana winds blow through Crazy Ex-Girlfriend and things get weird". TV Club. Retrieved March 15, 2019.