Abstract
Downslope and gusty winds in the lee of the Santa Ynez Mountains (SYM)
greatly influence the Santa Barbara (SB) coast in California. These
winds, known as ‘Sundowners’ due to their typical peak after sunset, are
characterized by northerly cross-mountain flow and strong stability at
mountaintop level. The National Weather Service (NWS) defines a
Sundowner when sustained cross-mountain winds greater or equal to 30 mph
or gusts greater or equal to 35 mph are observed at surface stations
located downwind of the SYM. In addition to gale-force winds,
temperatures above 100°F and relative humidity below 15% are not
uncommon during sundowners, and the marine layer influences the spatial
extent to which these strong winds may reach. These conditions have led
to turbulence which effects aviation at the local airport and the rapid
spread of multiple destructive wildfires in the region, including the
Jesusita Fire (2009), Sherpa Fire (2016), and Thomas Fire (2017).