Sundowner winds have fueled other destructive coastal fires
The "sundowners" that fueled the fire today in Santa Barbara have been the cause of numerous devastating fires along the region’s mountainous east-west coastline, bringing heavy Santa Ana-like winds around sunset.
"Sundowners" caused a 1990 blaze that destroyed hundreds of homes in Santa Barbara County as well as last year’s Montecito fire.
The sundowner effect can be so destructive because of the violent clash of hot air from the Santa Ynez Mountains and the cool air from 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."
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's website:
“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.”