"A tropical rain storm that caused deadly floods and destructive mudslides in the San Gabriel Mountains on Sunday was the kind of weather event seen only once about every 500 years, the National Weather Service said.
Starting at about 2:45 p.m., the storm dropped nearly 4 inches of rain onto Mt. Baldy in a single hour, triggering mudslides and floods that killed one motorist and severely damaged more than 30 homes.
The deluge also cut off the community of Forest Falls after mudslides of up to 10-feet high buried the town’s lone road connecting it to California 38. San Bernardino County firefighters were still assessing the damage Monday and Tuesday, but said about 100 buildings had sustained damage."