San Francisco braces for potentially historic El Niño

The big picture: Federal forecasters say there's an 83% chance of a record-breaking El Niño developing through the end of the year, KQED reports.

• El Niño is a climate pattern marked by unusually warm ocean waters in the tropical Pacific. It can shift weather patterns worldwide, sometimes bringing wetter winters to California.
• A recent UC Davis report identified several Bay Area locations that are particularly vulnerable to flooding, including runways at SFO and Oakland's airport, Highway 37 and the eastern approach to the Bay Bridge.
• Meanwhile, unusually warm ocean temperatures are already contributing to higher coastal water levels, with more extreme tides expected around Thanksgiving and Christmas, per the SF Chronicle.

Catch up quick: Mayor Daniel Lurie declared a local emergency late last week, allowing city departments to speed up purchases of storm-response supplies and prepare flood protections before severe weather arrives.

Flashback: The winter of 2022-23 offered a glimpse of the destruction heavy downpours can bring after multiple atmospheric rivers caused widespread flooding and damage across the Bay Area.

Threat level: The city is preparing for everything from flooded streets and downed trees to power outages and disruptions to Muni service.

The bottom line: A strong El Niño doesn't guarantee a disastrous winter, but San Francisco is preparing for the possibility that heavy storms and unusually high tides could arrive at the same time.