Santa Barbara area expecting Sundowner Winds with Red Flag
The National Weather Service has issued a Red Flag Warning for the Santa Barbara County Mountains and South Coast region for Thursday from 0900 hours through Saturday 1000 hours PDT. The area will see sundowner winds gusting up to 40 mph and relative humidity as low as 10%. These conditions, combined with temperatures reaching into the mid 90’s in the afternoons and 100’s in isolated locations, may contribute to explosive fire behavior. The regions most at risk are the foothills and through the passes and canyons.
A sundowner wind is an offshore northerly Foehn wind that occurs near Santa Barbara, California. The winds surface when a ridge of high pressure is directly north of the area, and they blow with greatest force when the pressure gradient is perpendicular to the axis of the Santa Ynez Mountains which rise directly behind Santa Barbara. These winds often precede Santa Ana events by a day or two, as it is normal for high-pressure areas to migrate east, causing the pressure gradients to shift to the northeast.
Significant Santa Barbara Sundowner Events
Sundowner winds are dried and heated by the warm inland valleys and deserts. As narrow canyons and valleys compress the winds, they become stronger and overpower the diurnal winds. Firefighting efforts during a sundowner wind event can become extremely dangerous as well as difficult. Three significant fires in the last three decades have resulted in part because of sundowner conditions.
- The Jesusita fire in May 2009 burned 8,733 acres and destroyed 80 homes while damaging 15 more. Most of the destruction occurred while sundowner winds pushed the main fire through populated areas.
- The Painted Cave Fire during June 1990 rapidly grew to 5,000 acres, destroying 427 buildings and killing 1 civilian.
- The Sherpa Fire grew to 4,000 acres overnight due to the sundowner winds, damaging the water system for El Capitán State Beach in the middle of June of last fire season.
Sources: Wikipedia, NIFC Fire history, LA Times, KEYT Santa Barbara