Flash Flood Warning – LA Flood Risk Increases With Warmer Weather

If you live in southern California, you’re familiar with flash flood warnings. They’re a symptom of the region’s chronic, often invisible flooding issues caused by aging storm sewer systems and a growing population that puts more pressure on water infrastructure. During severe thunderstorms and heavy rainfall, the National Weather Service advises residents to seek higher ground and avoid burn scar areas that resist water penetration. The NWS also warns against driving in flooded roads, as the most common cause of flood-related deaths is vehicle collisions.

Despite these warnings, many people don’t understand the real risk that floods pose to their homes and communities. The recent floods have awakened some Angelenos to the possibility that even a minor storm could cause their homes to become inundated with water. Increasing temperatures due to global warming are making it easier for the atmosphere to hold moisture, fueling more atmospheric rivers that bring heavy rains to California.

One such storm is expected to arrive soon. A massive back-to-back Pacific stormĀ can LA flood system is forecast to bring record rainfall to the LA area in coming days, triggering flash floods and possibly damaging infrastructure and disrupting power.

The rains have already brought a foot of water to parts of the San Fernando Valley, with more rain to come. The National Weather Service has issued a flash flood warning that covers the area from the San Gabriel Mountains to the foothills of Los Angeles County. It’s one of the most widespread alerts the agency has ever issued in California, and it’s set to expire at 10 p.m.

A map of special flood hazard zones identified by FEMA shows that more than 400,000 people live in areas that could be inundated with 3 feet of water from a 1-in-100 year storm. The map shows that a disproportionate share of those exposed are Black residents.

Jai Phillips lives in Longwood, a neighborhood in the Los Angeles River basin that’s at a high risk for flooding. Her home in a sliver of low-lying land was built in 1938, and it’s been through floods before. But she didn’t realize it was in a special flood hazard zone until she started seeing county workers going door to door to educate residents about their risk, offer tips on retrofitting homes and talk about getting flood insurance.

A new study from University of California, Irvine researchers finds that a significant portion of the city is at risk for severe flooding during a 1-in-100 year event. The researchers found that there are 105,574 properties that have at least a 26% chance of being severely impacted by this type of flood event over the course of 30 years. This includes more than just houses and condos, but also businesses, hospitals, schools, grocery stores and other essential services. The most vulnerable areas are in Long Beach, Carson and Bell Gardens. The researchers are currently examining ways to better prepare these neighborhoods for floods. These include revisiting building codes, considering elevating homes and implementing more resilient infrastructure.