Bill Patzert, climatologist for NASA's Jet Propulsion Laboratory in La Cañada Flintridge, said mudslides are par for the course in this region.
“There are four seasons in California – drought, followed by fire, followed by floods, followed by mudslides,” he said. “That’s the normal sequence that we live with, unfortunately.”
Patzert said the worst debris flows happen during an “atmospheric river event,” when 6-10 inches of rain falls in the course of two or three days. It’s fortunate, he said, that Tuesday’s mudslides weren’t preceded by more rain. It could have been worse.