Sundowner winds fan California fires

Wildfires fanned by winds gusting over 60 mph roared through the hills of Santa Barbarba, California yesterday, and continue to burn out of control today. A strong high pressure system to the north of Santa Barbara is driving a variant of the famed Santa Ana winds called the "Sundowner" winds. These winds blow from north to south from the mountains to the sea. Since the winds blow downhill, the air compresses and heats as it descends, resulting in very hot, dry conditions perfect for fires. The winds tend to peak in strength at sundown, thus the name "Sundowner" winds. A number of record high temperatures were set in the region yesterday, with 100°F recorded at the Santa Barbara airport, smashing the old record of 86° set in 1991. Record heat was also observed in Los Angeles, where the UCLA weather station reported a record high of 93° (old record: 89° in 1990). Humidities as low as 14% were observed yesterday in Santa Barbara.

Winds this morning were sustained at 44 mph gusting to 62 mph at Montecito, CA at 1500 feet in the mountains near Santa Barbara, and these strong winds are expected to continue today before dying down on Friday. Precipitation since the rainy season began October 1, 2008, in the Santa Barbara region, has been only about half or normal (Figure 1). With the winter/spring rainy season pretty much over, California can expect another severe fire year in 2009. The snowpack in the Sierras was mostly below average this winter, so water shortages will also be a problem this summer in California.


Figure 1. Percent of normal precipitation for the Southwest U.S. for October 1, 2008 - May 6, 2009. Image credit: NOAA AHPS.

For more information
Take a look at the wundermap for Santa Barbara, and turn on the "fire" layer.

Jeff Masters