Pacific Gas and Electric Company (PG&E) is monitoring a potential dry offshore wind event expected to begin Wednesday evening, Oct. 14, and last through Saturday evening, Oct. 17.
Due to the threat of high winds, dry conditions and extremely dried vegetation, PG&E may need to proactively shut off power in portions of 29 counties, including San Luis Obisbo, to reduce the risk of wildfires sparked by energized powerlines.
The potential Public Safety Power Shutoff (PSPS) event could affect approximately 70,000 customers. The shutoff is expected to last from Wednesday evening through Saturday afternoon.
Click here to see PG&E’s outage center map
PG&E sent one-day advance notifications Tuesday afternoon to customers in targeted areas. Initial customer notifications via text, email and automated phone call began Monday, approximately two days prior to the potential shutoff. Subsequent notifications, due to an increased scope, began Tuesday, approximately one day prior.
PG&E employees will conduct individual in-person visits, when possible, to customers enrolled in the company’s Medical Baseline Program who do not verify they have received these important safety communications. The primary focus will be on customers who rely on electricity for critical life-sustaining equipment.
At the time PG&E issued this release, the planned outage was approximately 12 hours away and conditions were subject to change.
What conditions are driving the potential shutoff?
The strongest winds are expected in the Sierra, southern Central Coast and portions of the North and East Bay.
Offshore Diablo winds will peak Thursday across the northern and central Sierra, as well as portions of the North and East Bay. Mono winds will be strongest Friday in the southern Sierra, with Santa Ana winds also expanding into southern Los Padres and across the Tehachapis on Friday. Strongest winds overall will be in the south, but relative humidity will be in the single digits and teens across most areas; vegetation is dry in all areas. New modeling tools have been implemented to allow for higher-resolution weather data, enabling PG&E to be more precise when scoping the affected area. Machine learning wind gust models at the weather station level help fill gaps left by coarser traditional weather models. Sectionalizing is another key factor.
PG&E initiates a PSPS when the weather forecast calls for such severe weather that people’s safety, lives, homes and businesses may be in danger of wildfires. Factors PG&E considers include:
Low humidity levels, generally 30% and below A forecast of high winds, particularly sustained winds above 19 miles per hour and wind gusts above 30-40 miles per hour Condition of dry material on the ground and low moisture content of vegetation A Red Flag Warning declared by the National Weather Service Real-time ground observations from PG&E’s Hazard Awareness and Warning Center and from crews working across the service territory
PG&E’s decision-making process also accounts for the presence of trees tall enough to strike powerlines. This set of criteria is a first step that may lead to further analysis by PG&E’s meteorology team to determine if a PSPS event is necessary.
Which counties are potentially affected?
Customers can look up their address online to find out if their location is being monitored for the potential safety shutoff.
The potential shutoff affects customers across 29 counties, including 3,920 Medical Baseline customers and 5 Tribal governments:
County Estimated Customers Impacted Estimated Medical Baseline Impacted Alameda 4,705 213 Alpine 660 9 Amador 48 5 Butte 3,098 256 Calaveras 8,550 407 Contra Costa 1,605 92 El Dorado 6,907 569 Fresno 3,934 275 Kern 1,117 48 Lake 57 4 Lassen 88 5 Madera 1,724 114 Mariposa 931 20 Mendocino 27 1 Napa 3,027 138 Nevada 2,238 95 Placer 9,063 681 Plumas 706 30 San Luis Obispo 10,460 357 Santa Barbara 1,100 26 Shasta 3,019 296 Sierra 1,149 46 Solano 30 1 Sonoma 1,783 69 Tehama 835 60 Tulare 281 9 Tuolumne 1,787 48 Yolo 8 0 Yuba 419 46
Tribal governments also affected:
Tribe Forecasted Customers Impacted Forecasted Medical Baseline Impacted Big Sandy Rancheria 59 2 Cold Springs Rancheria of Mono Indians 51 5 Mooretown Rancheria 4 1 North Fork Rancheria 2 0 Pit River Tribes 6 0
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