Potent Atmospheric River Storms Bring Heavy Rain and Flooding to California
A series of potent atmospheric river storms is hitting California, bringing heavy rain and flooding across the state.
California Under Flood Alerts as Storms Raise Flood Threat
More than 20 million people in California are under flood alerts as the first of two atmospheric river storms brings heavy rain and wind. This wet pattern is expected to continue well into February as an El Niño pattern kicks into gear.
El Niño causes changes in the jet stream, directing storms towards California. These storms can also tap into an extra-potent supply of moisture called an atmospheric river. While atmospheric rivers have been sparse in California this winter, that is changing this week.
The first storm is impacting Northern California and will move down the state, targeting Southern California. It is fueled by moisture from near Hawaii, earning it the nickname "pineapple express." Steady rainfall and gusty winds are expected, with cooler air overspreading the state.
Snow Accumulation and Flood Risks
The storm will bring more snow to Northern California and the Sierra Nevada, helping to replenish the state's snowpack. California's snowpack is currently at 52% of average for this time of year. Low-elevation mountain roadways could see at least 6 inches of snow.
There is also a risk of thunderstorms producing heavier rain in western California. Flooding is possible across a significant portion of the state, with roadways and low-lying areas being most at risk. Showery weather will continue on Friday as the storm slowly moves out of the region.
Second Potent Atmospheric River Storm Expected
Following the first storm, another, more potent atmospheric river storm is expected to arrive on Sunday. This storm could bring a prolonged flood threat, especially for Southern California. Forecast models indicate the potential for several inches of rain and lower elevation snow from Sunday to midweek.
Temperatures with the second storm are expected to be cooler, and below average temperatures and above average precipitation amounts are likely to persist into mid-February.
