Southern California is preparing for what is expected to be the largest storm of the season, bringing with it potentially damaging and life-threatening rain, wind, and flooding. This powerful atmospheric river is being amplified by a combination of climate change and El Niño, which are warming ocean waters and increasing the likelihood of significant downpours. Experts believe this storm offers a glimpse into the future of a warming world.
The current storm is being fueled by abnormally warm waters between California and Hawaii, where a long-lasting marine heat wave has persisted. Daniel Swain, a climate scientist with UCLA, explains that the warming of ocean and atmospheric temperatures leads to increased evaporation of water vapor into the lower atmosphere. This, in turn, results in more moisture in the lower atmosphere, contributing to heavier rainfall.
The warm ocean waters are partly a result of the climate pattern El Niño, which is associated with warm and wet conditions in Southern California. However, climate change is also a significant factor in driving up marine temperatures. While the exact extent to which each factor contributes is not clear, both are important players in the warming of the oceans.
The impact of the warm waters can already be seen this season, with California experiencing numerous thunderstorms characterized by intense downpours. In December, a storm in Oxnard delivered a month’s worth of rain in less than an hour. Last month, San Diego saw a historic event with more rain in a few hours than usual for the entire month of January. Experts believe the warm ocean waters played a role in both events, which were considered “thousand-year events” due to their rarity.
This pattern has continued with another atmospheric river causing heavy rain and flash flooding in San Francisco, Ventura, Long Beach, and San Diego. Swain emphasizes that warm ocean temperatures have been a crucial ingredient in each incident. This suggests that California’s future winters may increasingly resemble these conditions in a warming climate.
The upcoming storm is expected to bring similar conditions to a wide area of Southern California, including the Los Angeles area. Officials are preparing for up to 6 inches of rain, along with flooding, debris flows, and damaging winds. The National Weather Service predicts rainfall rates of half-an-inch per hour, with local rates of 1 inch per hour possible.
Authorities in Los Angeles County are closely monitoring areas prone to land movement and mudslides, especially those with recent burn scars. Preparations include clearing storm drains and flood control channels, as well as issuing warnings and potential evacuation notices in at-risk areas.
The forecast for this storm is subject to change as it approaches, but the potential for major hydrologic problems is significant. The weather service advises people to start preparing now for a major flooding event. This storm serves as a reminder of the potential impacts of climate change and the need to adapt to a warming world.
