Valley News -

Heavy rainfall poses flood, debris flow risks in Riverside County


Last updated 11/29/2018 at 12:05pm

Courtesy photo

The Post Holy Risk evacuations map was updated to narrow the areas where evacuations should occur first, based on the potential for danger. The revisions are based on in-depth geographic data analysis about the potential for debris flows, given the amount of rain predicted in approaching storms. Emergency officials can easily expand evacuation warnings/orders into other areas if rainfall totals are greater than expected.

RIVERSIDE – Heavy rainfall will douse the Inland Empire today amid strong winds and mandatory evacuation orders in parts of the Temescal Valley and Lake Elsinore prompted by fears of mudslides, debris flows and some flash-flooding along burn-scarred areas in the Cleveland National Forest.

City of Lake Elsinore Mayor Natasha Johnson was broadcasting live on Facebook periodically throughout the day, giving residents updates on how the city's mitigation plan was holding up.

"News reporters are reporting active debris flows in Lake Elsinore, so as you can see, we do have some active debris flow, but please be reminded, this is best-case scenario," Johnson said. "This is what we hoped for, so far. All the planning has been helpful, we are as prepared as can be."

She showed the Rice Canyon area where dirt berms were installed to guide any debris flows.

"We have continued debris flow, but again, the berms have so far been very successful in keeping the debris flow guided on the path," Johnson said. "Now the concern is, not just when the rain stops, but the saturation of the ground, and making sure that at any point, we're still ready for increased debris flow. All of the structures we have in place for guiding the current debris flow are successful."

The county's Emergency Management Department declared the need for immediate evacuations around 3 p.m. Wednesday, replacing a prior warning in which residents were advised to voluntarily relocate ahead of the heavy rain, which is expected to peak late this morning.

The mandatory evacuation applies to Lake Elsinore residents along Alberhill Ranch Road and Amorose Street, residents west of Laguna Avenue, 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

A care and reception center is open at Temescal Canyon High School, 28755 El Toro Road in Lake Elsinore.

Residents can house large and small animal at the care and reception center at the San Jacinto Valley Animal Campus, 581 South Grand Ave. in San Jacinto.

The National Weather Service is forecasting up to one inch of rain in Lake Elsinore, Corona and Riverside with the heaviest rainfall expected late this morning.

The county mountains are expected to receive up to 3.75 inches of rainfall today, according to the NWS. Snow levels are predicted to drop to 6,000 feet.

The NWS issued a winter weather advisory for portions of the Riverside County mountains above 6,000 feet from noon today to 2 a.m. Friday.

The Coachella Valley will receive around two-tenths of an inch of rain and the San Gorgonio Pass near Banning is expected to see up to 2 inches of rain, according to the NWS.

A flash flood advisory will be in effect from 6 a.m. Thursday to 3 a.m. Friday for the Riverside County mountains, the San Bernardino County mountains and Orange County inland areas, which includes a small southwest portion of Riverside County west of La Cresta.

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.

Rainfall is expected in the burn zone created by the 13,000-acre Cranston Fire, but officials do not anticipate the rain will be heavy enough to trigger debris flows. But both Idyllwild and Pine Cove were included in a flash flood watch in effect until 3 a.m. Friday, but as of 3 p.m. Wednesday no evacuation orders had been issued for the area.

The storm was generating strong, gusty winds, prompting the NWS to issue a wind advisory from 8 a.m. to 6 p.m. today for the San Gorgonio Pass near Banning, the county valleys, Idyllwild and Pine Cove. The Coachella Valley was not included in the wind advisory.

Rainfall rates of around one-half inch per hour will be possible on the southwest facing slopes of the San Gabriel and San Bernardino mountains late this morning, said NWS meteorologist Greg Martin. The heaviest rainfall is expected to clear the mountains by this afternoon followed by widespread rainfall this evening.

High temperatures today are expected to reach 63 degrees in Riverside, 56 in the county mountains, 68 in the San Gorgonio Pass near Banning and 75 in the Coachella Valley.

A second, weaker storm is expected to bring rain Saturday afternoon into Sunday morning.


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