Two Atmospheric Rivers Lashing California, Causing Flooding and Heavy Rainfall
Image source: CNN
First Storm Expected to Strike Southern California
The first of two atmospheric rivers is forecasted to hit Southern California on Thursday, bringing with it gusty winds and heavy rainfall that may lead to flooding in certain areas [1].
Over 20 Million People Under Flood Alerts
More than 20 million people across California have been issued flood alerts as storms threaten flash flooding in cities like San Diego, Sacramento, San Francisco, San Jose, and Oakland. The flood threat is expected to last until Friday morning [1].
Another Stronger Storm Forecasted
Although there may be a brief respite after Thursday’s storm drenches Southern California, a second atmospheric river, potentially stronger, is poised to move across the region starting from Sunday [1].
El Niño Pattern and Its Influence on the Weather
Rainy conditions are expected to persist well into the next month as a more typical El Niño pattern comes into effect. El Niño, a natural phenomenon in the tropical Pacific that influences global weather, can cause changes in the jet stream, leading storms to target California. These storms can tap into a moisture supply known as the atmospheric river, which originates in the tropics [1].
View this interactive content on our website
Two Atmospheric River Storms Continue Their Reign
On Wednesday, the first of two atmospheric river storms pummeled Northern California. As the storm shifted south, central California experienced a steady downpour that will continue into Thursday [1].
Locations Most Affected by the Storm
The heaviest rainfall is expected from areas north of San Luis Obispo to the California-Oregon state line, which includes the Bay Area. Southern California will start to see steady rainfall and periods of stronger winds by Thursday morning, along with a decrease in temperature [2].
Potential Rainfall and Flood Risks
Rainfall of 1 to 4 inches is projected in the southern part of the state, with rates exceeding 1 inch per hour. Southern California is at a Level 2 out of 4 risk for excessive rainfall, with roads and low-lying areas being the most susceptible to flooding. Rising water levels in certain waterways are also possible [2].
Preparations and Response Efforts
California officials are taking action and preparing for potential impacts. Hundreds of crew members from multiple agencies are on standby to respond to rescue calls. Governor Gavin Newsom stated, “The state is working around the clock with our local partners to deploy life-saving equipment and resources statewide” [2]. The California Office of Emergency Services has also readied swift water personnel and equipment in 12 counties for immediate action [3].
Winter Conditions and Snowfall in Northern California
Northern California is bracing for wintry weather, with more snow expected to accumulate at lower elevations and several feet of snowfall in the Sierra Nevada. Winter storm warnings are in effect, with up to 4 feet of snow predicted in higher elevations [3].
Improving the Water Supply: California’s Snowpack
The snowfall is of great importance for California’s snowpack, which is currently at 52% of the average for this time of year. The state’s snowpack is a vital water source, and California relies on it to determine the water availability for the remainder of the year [3].
Forecast for the Coming Days
Showery weather is expected to persist on Friday throughout California as moisture gradually moves across the Southwest. Moreover, a more potent storm, driven by an atmospheric river, is projected to strike Southern California starting from Sunday. Meteorologists predict this storm to become the largest of the season, with extended flood threats and a chance of significant snowfall in lower elevation areas [3].
