Parts of Southern California face the possibility of power shutoffs this week as hot, dry and windy conditions elevate the threat of wildfires across the region.
Southern California Edison has warned more than 162,200 of its customers about proactive power shutoffs in high-risk fire areas. The alert comes ahead of strong winds in the forecast for Thursday and Friday, which can fan brush fires sparked by downed power lines.
“Those winds are going to hold off for one more day before they get really strong,” said NBC4 forecaster Shanna Mendiola. “We will be seeing the humidity go down, the heat go up, and that fire threat go up, as well.”
Here’s what to know.
What Areas Are Being Considered for Power Shutoffs?
Los Angeles County: 21,302 customers
- Azusa, Covina, Glendora, Lancaster, San Fernando, Santa Clarita.
- Unincorporated areas including Rowland Heights, Vincent, Falling Springs, Leona Valley, Lake Hughes, Green Valley, Lake Elizabeth, Cantillas, Canyon Country, Lakeview Terrace, Agua Dulce, Mint Canyon, Chatsworth, Alta Dena, Acton, Singing Springs, Letteau Canyon, White Heather, and Boiling Point, Portal Ridge, Castaic, Mount Disappointment and Mount Wilson.
Orange County: 5,758 customers
- Irvine, Orange and unincorporated areas including El Modena, Trabuco Canyon, and Robinson Ranch.
Riverside County: 48,037 customers
- Banning, Beaumont, Desert Hot Springs, Palm Springs, Hemet, San Jacinto, Menifee, Perris
- Unincorporated areas including Banning Pass, North Palm Springs, between Beaumont and Banning, Riverside County, San Jacinto, Lake Perris North Shore, Lakeview**, Nuevo**, Moreno Valley, Perris, Lake Elsinore, Temecula, Weldon, Lake Isabella, Bella Vista, Cherry Valley, Lakeview Hot Springs, Cabazon, Med Valley, Goodhope, Eden Hot Springs, Juniper Flats, Gilman Hot Springs, Big Oaks Canyon, Owl, portions of Desert Hills Outlet Mall, and Mountain Center
San Bernardino County: 53,501 customers
- Fontana, Rancho Cucamonga, San Berndardino, Rialto, Upland, Yucaipa
- Unincorporated areas including southern Morongo Valley, Oak Glen, Lytle Creek, Etiwanda, Grapewine Canyon, San Sevaine Flats, Alta Loma, Chaffey College School, Verdemont, Hudson, Ridgeline, Cajon, Arrowhead, Phelan, Devils Canyon, Serrano Village, Kendall, University, Arrowhead Farms, North Park, San Bernardino High School, Shandin Hills, Rim of the World, Del Rosa, NE Sterling, Nena, Big Oaks Canyon, Snow Peak, Devore Heights, Devore, Wildwood Park, Cedar Pines Park, Valley of Enchantment, Crestline, Silverwood Lake, Twin Peaks, Agua Fria, Muscoy, Carey, Lincoln Crest, Leona Valley, Las Plazas, Alessandro, Roosevelt, Mount Vernon, Mentone, Running Springs, and North of Lake Arrowhead
Ventura County: 20,410 customers
- Camarillo, Fillmore, Moorpark, Ojai, Santa Paula, Simi Valley, Ventura
- Unincorporated areas including El Rio, Santa Susana Mountain, Sespe, Oak Village, Bardsdale, Lotus Canyon, Cavin, Saticoy, Limon, Somis, Buckhorn, and Piru
Kern County: 13,268 customers
- Tehachapi
- Unincorporated areas including Kernville, Cyrus Flats, Golden Hills, Old Town, Alpine Forest, Weldon, Lebec, Kern County, Walker Basin, Bear Valley Springs, Stallion Springs, Keene, Loraine, Sand Canyon, and Twin Oaks, South of Twin Lakes
Why Shut Off Power?
Most of the deadly California fires over the past several decades, including the fire that destroyed the town of Paradise in Northern California, have been the result of power lines in high-wind situations.
Add in Southern California’s infamous Santa Ana winds, and you have extermely volatile conditions. Santa Ana winds, which can fan flames sparked by downed power lines, are expected to pick up Thursday during one of the worst times of the year for wildfires.
The winds will develop by early Thursday and continue through Friday.
Where Are the Possible Outage Areas?
For a detailed listing of all areas affected and maps to check if you may face a proactive shutoff, visit SCE’s Public Safety Power Shutoff page.
Only SoCal Edison customers are affected by the shutoffs. Customers in the LADWP service area will not face power shutoffs. The LADWP does not shut off power due to strong winds, in part because the highly urbanized area has fewer wildfire prone areas.
How Proactive Power Outages Work
Meteorologists and other SoCal Edison staff members use high-resolution weather data maps and other tools to monitor extreme fire weather. SoCal Edison also uses weather stations, historical data and fire monitoring cameras to determine fire potential.
If conditions warrant, the utility will shut off power in high-risk areas. Customers can receive notifications about outages in their area through emails, text or phone calls. The utility will alert first responders, local governments and customers of power shutoff.
Here are some of the factors the utility considers before declaring an outage.
- High winds, including red flag warnings
- Low humidity
- Dry vegetation that provide fire fuel
- On-the-ground observations
- Fire threat to electric infrastructure
- Public safety risk
An initial notification is sent out about two days before a possible shutoff to warn customers. A second notification will be sent a day before, then notifications are sent when power is shut off and when it’s restored. Restoration is based on when weather conditions are deemed safe.
Customers can view this map to see whether they’re in a high-risk area.
Why Are Santa Ana Winds So Dangerous?
The fire-whipping winds are produced by surface high pressure over the Great Basin squeezing air down through canyons and passes in Southern California’s mountain ranges. They’re common in the fall and have a long history of fanning destructive wildfires in the region.
Fall is historically the worst time of the year for damaging wildfires in California. Seven of the state’s 10-most destructive wildfires have occurred in October and November.
Through mid-October, more than 4,800 fires burned nearly 47,000 acres in California. During the same period last year, 5,155 fires burned a staggering 631,900 acres. California’s five-year average for that timeframe is 5,109 fires and 372,344 acres burned.
Photo Credit: Noah Berger/AP
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Source: NBC Los Angeles