Residents living in the burn areas of the Palisades, Sunset and Hurst fires are particularly susceptible to flooding and mudslides and should be prepared to evacuate, the Los Angeles Fire Department officials warned.

The evacuation orders will be in effect from 7 a.m. Wednesday to 6 p.m. Thursday, amid the heaviest downpours. Residents under evacuation orders and high risk areas will be visited at home by Los Angeles Police Department officers. If no one is home, a flyer will be left on their door.

Residents in the evacuation warning zones may choose to leave preemptively or be prepared to leave on a moment's notice.

The storm is expected to drop as much as four inches of rain in some parts of the Los Angeles.

"The time period of greatest concern is overnight Wednesday into Thursday morning. Rainfall amounts are predicted to be from 1-2 inches on the coasts and valleys and 2-4 inches in the foothills and mountain areas," Los Angeles Emergency Management Department warned. " Get ready and take extra precautions, especially if you are in an area impacted by the recent wildfires."

Fire officials said the following burn areas were "especially susceptible to heavy rain":

: Getty Villa area, Highlands near the burn areas, Bienveneda area near Temescal Canyon Park, Rivas Canyon/Will Rogers State Park area, Mandeville Canyon above Tanners Road, Old Ranch Road and Rustic Creek;

: East and south of Runyon Canyon;

: Olive Lane in the Oakridge Mobile Home Park;

Caltrans will close a segment of Pacific Coast Highway to residents and businesses in burn scar areas at noon Wednesday. At that point, only emergency vehicles and U.S. Army Corps of Engineers contractors will be allowed to pass.

It's not yet clear when PCH will reopen to residents and businesses. Caltrans and other officials will reassess the situation Thursday to determine if the highway can reopen to residents and businesses with passes by Friday for morning commute.

LA County Public Works crews have prepared debris basins, stabilized slopes, and reinforced drainage systems to reduce flood risk, particularly in recent burn areas including Eaton, Palisades, Bridge, Hurst, Kenneth, Hughes, Sunset, Lidia and Franklin, officials said.

"While these efforts reduce flood risk, the storm could still bring moderate debris and mudflows to burn areas, potentially blocking streets and threatening structures depending on their location and the local terrain," the department said.

"To mitigate potential impacts, LA County Public Works has activated 24/7 storm patrols and remains fully mobilized," officials added.

Through Tuesday night, rainfall was expected to range from one-third to two-thirds of an inch from the coast to the mountains with local amounts exceeding one inch in the mountains, the National Weather Service said.

A cold front will move over the area overnight Wednesday into early Thursday, bringing a storm with potential flooding.

"Lighter precipitation will develop on Wednesday with the most likely time for more widespread and heavier precipitation with the cold front for late Wednesday night into Thursday morning," the NWS said.

This system will also likely be the biggest snow maker of the season, with 1 to 2 feet of snow forecast for higher elevations.

"Steady rain will turn to showers Thursday. The snow levels will drop to around 3,000 ft and a few inches of snow is possible over the Grapevine and other lower elevations passes," the NWS said.

Stronger, gusty southwest to west winds will develop Wednesday night and continue through Thursday night, the NWS said.

Cooler temperatures are expected all week, with daytime highs dropping to around 60 degrees in downtown Los Angeles on Tuesday and Wednesday and around 55 on Thursday and Friday. Overnight lows will generally be in the 40s and lower 50s, but will drop into the 30s on Thursday and Friday in the mountains and the Santa Clarita and Antelope Valley.

A weaker storm system moving inland to the north on Friday could keep some showers going into Friday night, according to forecasters. However, things dry out and warm up for the weekend.

The Los Angeles Emergency Management Department urges residents to prepare ahead of time by:

During the storm, residents should:

• limit driving in burn areas;
• give yourself extra time to safely drive to your destination;
• call 911 with any life-threatening emergencies;
• call 311 to report downed tree branches, blocked storm drains, or localized flooding.

City News Service contributed to this report.