when will the heaviest rain arrive in Southern California?

The National Weather Service has released its most detailed forecast to date for the arrival and intensity of rain associated with Hurricane Hilary. 

Hilary, which reached Category 4 strength on Friday, is expected to be downgraded to a tropical storm by the time it reaches Southern California on Sunday.

Light rain will begin to fall in Los Angeles, Orange, Riverside and Ventura counties between 6 p.m. and midnight on Saturday, NWS said, and continue through the morning. The rainfall intensifies Sunday afternoon and peaks during the evening and overnight hours into Monday.

Peak rain rates will be .50 to 1.0 inches per hour with higher amounts, 1.0 to 1.5 inches per hour, in the mountains and deserts. 

Hilary will continue to drench the region into Monday afternoon when rain begins to taper off, according to the NWS.

Rainfall total estimates through Monday are 1.5-3 inches for most coastal/valley areas in L.A./Ventura counties, with 3 to 7 inches possible in the L.A. County mountains and Antelope Valley.

“Prepare for life-threatening flooding of small streams, creeks, arroyos, and ditches, as well as debris flows in burn scars,” NWS said in a bulletin. “In addition, there will be the threat of rock and mudslides, especially in the mountains and canyons. Significant roadway flooding will be possible, causing dangerous driving conditions.”

The latest National Hurricane Center track continues with a slightly more eastward track, with the center of the tropical storm making landfall slightly east of San Diego around 6 p.m. Sunday.