MONTECITO (CBSLA) — Fire-scarred communities still digging out from under a mudslide are getting ready for another storm that promises to dump heavy rain overnight, forcing mandatory evacuations in Santa Barbara County.

Flash flood watches are in effect in the foothills of Los Angeles and in Santa Barbara County, where last month a deadly mudslide devastated the wealthy seaside enclave of Montecito.

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The mandatory evacuation area as of March 1. (credit: Santa Barbara County Sheriff’s Department/ESRI)

Santa Barbara County Thursday issued mandatory evacuation orders for burn areas in the Goleta, Santa Barbara, Montecito, Summerland and Carpinteria areas. They apply to the Thomas, Sherpa and Whittier fire burn areas. The evacuation order took effect at noon. Residents must be out by 6 p.m.

“The extreme impact of the storm is expected to be in our area between 2 a.m. and 8 a.m. Friday morning,” Santa Barbara County Sheriff Bill Brown said at a news conference Thursday.

“This is the first storm since the 1/9 debris flow and we cannot take any unnecessary chances,” he said. “We want everyone to be safe and out of harm’s way.”

Light rain was seen in the area by 9 p.m. Earlier in the day, deputies from the Santa Barbara County Sheriff’s department were knocking on doors, ensuring residents were heeding the evacuation order and posting notices.

“It is therefore very important that you spread the word about this evacuation,” Brown said. “Tell your family members, neighbors and friends.”

He urged parents to promptly pick up their children from school Thursday, and to wait for word from schools on the status of classes Friday.

Twenty-one people were killed and hundreds of homes were destroyed or damaged in the Montecito mudslides that occurred on Jan. 9 in the area burned by the Thomas Fire, the largest wildfire in California history. The mudslides destroyed at least 65 homes and damaged more than 460 others.

“[We’re] taking precaution. I think now, since, you know, something’s happened, we just never know what else is gonna happen,” Montecito resident Mark Alfano told CBS2 News Thursday evening. “I think the best you can do is listen to the evacuations, at this point, and be somewhere safe.”

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“The heaviest rain is expected to happened Thursday night through Friday morning, when rainfall rates could reach a half-inch per hour, meeting the very low end of the USGS criteria for mud and debris flows over the Whittier, Thomas, Creek and La Tuna burn areas,” the National Weather Service said.

For comparison, half an inch of rain fell in five minutes during the storm that led to last month’s mudslide, which brought down boulders and trees and leveled homes in Montecito. Residents in the area are under an evacuation warning, which could be upgraded to a mandatory order.

“Rainfall of this intensity can produce dangerous mud and debris lows near the Creek and La Tuna burn areas,” the NWS said.

Burbank city officials distributed sandbags to residents hoping to protect their properties from flooding or mud from the La Tuna fire burn area. Several cars and homes were damaged in a mudslide in that area last month.

The Los Angeles Fire Department was offering ready-to-fill sandbags at all of its stations, and sand is available at select locations. More information is available on the LAFD website.

A voluntary evacuation order was issued for parts of Ventura County Thursday evening for homes along Nye Road, as well as Matilija Canyon, Hwy 33/North For and the Vista Fire burn area divison Z and B.

(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. City News Service contributed to this report.)