LOS ANGELES (CBSLA) — The first major storm to hit Southern California this rainy season prompted mandatory evacuations, as well as causing heavy debris and mud flow throughout the Holy Fire burn area.
Overnight rainfall was mostly light, but the National Weather Service says the heaviest rain is expected in Orange County and inland areas late Thursday morning.
"Hourly rainfall rates in stronger showers and isolated thunderstorms could approach one-half to one inch in an hour," according to the NWS. "This could lead to mudslides and debris flows at recent burn scars. The time window of greatest concern is from late Thursday morning through early Thursday evening."
Evacuation orders were issued for about 4,000 homes in the Holy Fire burn area straddling Orange and Riverside counties. Mandatory evacuations were issued Wednesday for several Riverside County areas, where a handful of schools were also closed.
A flash flood warning was issued for Riverside County and parts of Orange County at about 10 a.m. As the storm moved into the area, the Trabuco Creek area in Orange County and the Glen Ivy B Zone in Riverside County were ordered to evacuate soon after, while residents of Rose Canyon remained under voluntary evacuation order.
Most areas should see between a half-inch and two inches of rain, although three inches could fall at higher elevations and foothills.
With the storm expected to dump as much as half an inch of rain an hour on coastal slopes in Orange, western Riverside counties and into southwest San Bernardino County, a flood advisory was issued for the area until at least 11:45 a.m. A flash flood warning was in effect for burn areas in Corona and Lake Elsinore until noon, and debris flow swept through Trabuco Canyon.
To the north, residents in burn areas scorched by the Woolsey Fire, the Hill Fire and last year's Thomas Fire are also bracing for possible mudflows. Ahead of the storm, residents made preparations in Malibu, much of which was devastated by the Woolsey Fire this month. Authorities say evacuation orders are not out of the question for these areas.
The Los Angeles County fire and sheriff's departments both deployed additional staffing into the burn area in light of the threat of potentially damaging flooding. Officials with both agencies stressed the need for residents to adhere to whatever evacuation orders are issued.
"Evacuation orders should not be taken lightly and are ordered because there is a threat to life and property," according to a joint statement from the agencies.
The rain and the uncertainty of the canyon roads it is surrounded by prompted Pepperdine University to cancel classes and close its offices on its Malibu campus.
Flood advisories were issued for Thousand Oaks, Simi Valley, Agoura Hills, Westlake Village, Oak Park, Malibu, Woodland Hills, Calabasas and Malibu Creek State Park through 9:15 a.m.
(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. City News Service contributed to this report.)
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