The strongest in a series of three storms was sliding into the Southland Sunday evening, with forecasters warning of possible thunderstorms overnight and sheriff’s officials warning people in some Topanga Canyon neighborhoods to prepare for evacuations if flooding occurs.
Despite cloudy conditions, Sunday was relatively dry, and many areas enjoyed some sunshine. But forecasters said the latest burst of rain was expected to arrive by late Sunday night into Monday morning.
“Periods of rain are expected through Monday as a series of storms move through the area,” according to the National Weather Service. “Additionally, there is a 20 to 40 percent chance of thunderstorms late (Sunday night) into Monday evening.”
Forecasters said the storm could produce rain falling at a rate of roughly three-quarters of an inch per hour, and there was a slight chance of rates as high as an inch per hour.
“Storms will likely be fast moving but the low level wind profile will be supportive of some back-building that could prolong the periods of heavy rain in isolated areas,” according to the NWS. “As a result, isolated flooding issues are possible, mostly in areas where thunderstorms develop.”
In response to the potential flooding risk, the Los Angeles County Office of Emergency Management issued an evacuation warning for residents in the Topanga Canyon area, affecting the area along Santa Maria Road north of Topanga Canyon Boulevard. The warning took effect at 9 p.m. Sunday and will remain in force until 6 a.m. Tuesday.
The warning urged residents to prepare for possible evacuations.
“Gather loved ones, pets and supplies,” the warning stated. “Monitor local weather, news and alertla.org for more information.”
A flood watch will be in effect most of the day Monday in Orange County coastal and inland areas, along with the Santa Ana Mountains and foothills.
As of Sunday night, there were no flood advisories or warnings in place in Los Angeles County.
“Showers and storms expected to start tapering off Monday afternoon, with most of the precipitation done by Monday evening except for some lingering showers over the north facing mountains as the winds shift around to the northwest,” according to the NWS. “Gusty northwest winds are likely in the mountains early Tuesday. Snow levels expected to remain above 7,000 feet through the bulk of the event but could drop briefly to around 6000 feet later Monday night.”
The rain was affecting some Southland amusement parks. Six Flags Magic Mountain was closed Saturday and will also be closed Sunday and Monday, with tickets purchased for those days honored through Dec. 29.
Knott’s Berry Farm announced the park closed early at 6 p.m. Saturday due to inclement weather. Unused tickets purchased will be valid until Feb. 25.
Due to the rainfall, the Los Angeles County Department of Public Health advises beach users to avoid all water contact, especially near discharging storm drains, creeks and rivers due to potentially higher bacteria levels in these areas. This includes any runoff that may flow onto or pond on the beach sand.
The advisory will be in effect until at least 11 a.m. Tuesday.