Parts of the Temescal Valley and Lake Elsinore were placed under a mandatory evacuation Wednesday with the approach of a winter storm that’s expected to trigger flooding, mud slides and debris flows along burn-scarred areas in the Cleveland National Forest.
The county’s Emergency Management Department declared the need for immediate evacuations around 3 p.m., replacing a prior evacuation warning in which residents were advised to voluntarily relocate ahead of the heavy rain, which is likely to begin late Wednesday night.
The mandatory evacuation applies to Lake Elsinore residents along Alberhill Ranch Road and Amorose Street, as well as residents on Glen Eden Road south of Corona, the Glen Ivy Hot Springs community, the Horsethief Canyon community, and the area around McVicker Park in Lake Elsinore.
A map delineating exactly which neighborhoods are impacted is available at rivcoready.org/Have-a-Plan/Flooding/Storm-Ready .
A care and reception center is open at Temescal Canyon High School, 28755 El Toro Road in Lake Elsinore.
The National Weather Service is forecasting around one-tenth of an inch of rain Wednesday evening in Lake Elsinore, Corona and Riverside before the storm system dumps over an inch of rain in the same areas Thursday.
The county mountains are expected to receive two-tenths of an inch of rainfall Wednesday evening and up to 3 inches of rainfall Thursday, according to the NWS. Snow levels are predicted to drop to 5,500 feet.
The Coachella Valley is not expected to see any rainfall Wednesday and will receive less than one-tenth of an inch of rain Thursday, according to the NWS. The San Gorgonio Pass near Banning is expected to get less than one-tenth of an inch of rain Wednesday evening and up to a quarter inch of rain Thursday.
A flash flood advisory is in effect from 6 a.m. to 8 p.m. Thursday for portions of Riverside County.
The burn-scarred slopes — the result of the August Holy Fire that began on the Orange County side of the Cleveland National Forest — are highly susceptible to heavy runoff that could prove damaging, according to county officials.
Multiple community meetings have been held over the last two months to inform residents of the risks and what to do in the event of a big storm. The Holy Fire, allegedly the work of an arsonist, scorched roughly 23,000 acres.
Officials are also anticipating flooding in the burn zone created by the 13,000-acre Cranston Fire in the San Jacinto Mountains. Both Idyllwild and Pine Cove were included in a flash flood watch in effect until 3 a.m. Friday.
The storm, packing 30 mph winds, will spread southeast into Southern California, and the heaviest rainfall is expected late Thursday morning into Thursday night, according to the NWS.
“Light rainfall is expected to develop this evening, with heavier rainfall developing on the south-facing coastal slopes of the San Bernardino Mountains toward daybreak on Thursday. Rainfall rates of around one-half inch per hour will be possible on southwest facing mountain slopes,” forecasters said in a statement. “These rainfall rates are capable of causing local urban flooding, ponding of water in poorly drained areas and deadly mud slides and debris flows on and below recent burn areas.”
Temperatures are expected to drop, with highs in the Riverside metropolitan area Thursday hovering in the upper 50s.
A weaker storm system is likely to edge into the region Saturday, producing little if any precipitation.