A historic heat wave is affecting the West, breaking all-time, monthly and daily records and putting the California electricity grid to test. The heat is relentless, potentially peaking today but sticking around straight through the upcoming weekend.
The big picture: The immediate cause of the heat wave is an unusually strong area of high pressure, or heat dome, that is parked over the western U.S., causing air to sink and dry out, stifling any widespread rainfall.
- As of Tuesday morning, about 52 million people were under extreme heat warnings and advisories in six states.
Threat level: California ISO, the state's grid operator, on Tuesday afternoon declared a Stage 2 emergency, telling Californians "to be ready for potential rotating power outages."
- Grid management was expected to be more difficult on Tuesday with a forecast for record power demand. A Flex Alert is in effect for a seventh-straight day, calling on residents to conserve energy between 4 and 9 pm PT.
- California ISO says it needs two to three times the voluntary load reductions seen in the past few days to avoid rotating power outages.
- Yesterday, California ISO declared a separate Stage 2 emergency, switching on emergency generating capacity as demand threatened to exceed supply.
- Much of this emergency energy supply comes from natural gas plants, including generators meant specifically to kick on in events such as this one.
- Stage 3 emergencies trigger load shedding, otherwise known as rolling outages.
By the numbers: Here are a few of yesterday's notable records in California:...
- 112°F: High in Stockton, setting a