A powerful atmospheric river storm is expected to hit California this Wednesday, bringing heavy rains and significant snowfall to the mountains. This is the latest in a series of intense storms that are getting worse, according to new research.

Much of northern California is under a winter storm warning due to strong winds and heavy snowfall that the National Weather Service warns will make travel difficult or impossible. Severe thunderstorms and high winds are also forecasted in the San Francisco Bay area.

A flood watch has been issued in southern California through Thursday afternoon, with dangerous driving conditions and the risk of road flooding and debris flows in areas affected by recent wildfires. Los Angeles has placed several areas under evacuation warnings and closed several roads, including a portion of the Pacific Coast Highway.

The state’s office of emergency services has sent over 400 workers, including rescue teams and search personnel, across the state to prepare for the storm. Residents have been advised to have emergency bags and be prepared for power outages.

Atmospheric rivers are crucial in replenishing the state’s reservoirs and snowpack, but they have also been responsible for some of the most devastating storms in California. Research has shown that these events are increasing in frequency and severity due to the warming of the planet.

According to a comprehensive study, atmospheric rivers have increased in the area they affect by 6% to 9% since 1980, increased in frequency by 2% to 6%, and are slightly wetter than before.

While atmospheric rivers can bring much-needed rain to drought-stricken areas, they are often dangerous. Several atmospheric rivers have caused mudslides and killed people in California in recent years.

These events occur all over the US and the world, though some may not be recognized as atmospheric rivers. An atmospheric river in New England in 2023 brought a foot of rain and 50mph winds, while a 2020 atmospheric river in Alaska dumped 99 inches of snow.