As a powerful storm nears the South Coast, the pre-evacuation advisory for “anyone who lives near a burn area in Santa Barbara County” conveys a painful reality: No one knows when or where the next torrent of mud and boulders will come surging down the scorched mountainside into town.
But it’s a good bet that it could happen, given enough rain. According to a recent report by a team of state hydrologists and geologists, 50 out of 138 streams and tributaries in the mountains above Montecito and Carpinteria have a 60 percent or greater likelihood of producing debris flows in the aftermath of the Thomas Fire, based on a rainfall rate of about 1 inch per hour.
The same relatively high odds were reported for Ventura County burn areas. The risks could remain high for two to five years, until the vegetation grows back, scientists said.