Dangerous 'sundowner' winds made Montecito fire explode
The fire in the hills of Montecito destroyed dozens of homes in what seemed like a flash Thursday evening, fanned by a weather pattern unique to the Santa Barbara area.
Firefighters say the Tea blaze was fanned by "sundowner winds." The "sundowners" have been the cause of numerous devastating fires along Santa Barbara's mountainous east-west coastline, bringing heavy Santa Ana-like winds -- in the case of Montecito, blowing up to 80 mph -- around sunset. "Sundowners" caused a 1990 blaze that destroyed hundreds of homes in Santa Barbara County.
The sundowner effect can be so destructive because of the violent clash of hot air from the Santa Ynez Mountains and the cool air of the Pacific Ocean. According to Accuweather, "This katabatic [downhill] wind warms and dries out the air as it descends the mountains and displaces the usually cool, moist air at the coast. When the wind is funneled through the passes and coastal canyons it can cause wind gusts of tropical storm of hurricane force. Two cities, Goleta and Montecito, are places where the strongest winds can usually be found."
UCLA professor Warren Blier described the weather event this way:
Called Sundowner winds because they often begin in the late afternoon or early evening, their onset is typically associated with a rapid rise in temperature and decrease in relative humidity. In the most extreme Sundowner wind events, wind speeds can be of gale force or higher, and temperatures over the coastal plain, and even at the coast itself, can rise significantly above 37.8°C (100°F). In addition to causing a dramatic change from the more typical marine-influenced local weather conditions, Sundowner wind episodes have resulted in significant property and agricultural damage, as well as extreme fire danger. They have, in fact, been associated with many of the most destructive conflagrations that have occurred in the Santa Barbara region.
Sundowners are similar to the Santa Ana winds that have fueled many brush fires around Southern California. Both are formed by strong surface high pressure over the great basin, according to the Montecito Fire Department:
Sundowners are also formed by building high pressure, however, this high pressure is much weaker but much closer to the Santa Barbara South Coast. Usually when the winds are fairly strong along the Central Coast of Santa Barbara and San Luis Obispo Counties to the north, high pressure builds near Santa Maria behind the Santa Ynez range. As this high pressure builds, the same rule comes in play ... air flows from high to low pressure. Air pushes through the passes and canyons of the Santa Ynez Range, especially through the Gaviota Pass, San Marcos Pass, Montecito foothills, and some smaller canyons. The wind that results is more of a northwest to northeast wind and is usually quite strong.
-- Shelby Grad
Photo: Michael Robinson Chavez / Los Angeles Times