Almost 1 million Californians without power amid second atmospheric river impact in a week

California is grappling with the effects of a second atmospheric river in just one week, as heavy rainfall and high-elevation snow continue to pummel the state on March 14, 2023. The National Weather Service (NWS) has warned of a high risk for excessive rainfall today, with the storm expected to persist into Wednesday, further exacerbating the potential for widespread flooding.

The powerful atmospheric river is forecast to produce multiple rounds of heavy rain and mountain snow across central and southern regions of California until tonight (LT). In combination with snowmelt below 1 524 m (5 000 feet), the heavy precipitation is likely to cause widespread flooding, particularly in areas that remain vulnerable due to recent rainfall. The situation could result in significant flooding impacts.

As a response, numerous Flood Watches, Warnings, and Advisories have been issued, along with a High Risk (level 4/4) of Excessive Rainfall for parts of the southern Sierra Nevada foothills and central and southern California coast.

The storm system is predicted to move further inland, affecting the Intermountain West by tonight, while the accompanying cold front completes its journey through southern California early on Wednesday, bringing an end to the excessive rainfall threat. In addition to the heavy rainfall, the potent storm is anticipated to generate heavy mountain snow from the Sierra to the central and northern Rockies through Wednesday and trigger gusty winds.

As the cold front enters the Southwest on Wednesday, locally heavy rain may also lead to isolated flooding in parts of central Arizona.

By 21:00 UTC on March 14, around 380 000 customers — or about 950 000 people — in California are without power.

This is the second atmospheric river event to impact the state in a week. The previous storm resulted in two fatalities and forced thousands to evacuate their homes.

Dangerous excessive rainfall event underway across much of Central California, widespread severe flooding expected

References:

¹ Short Range Forecast Discussion – NWS Weather Prediction Center College Park MD – 346 PM EDT Tue Mar 14 2023

Featured image: NOAA/GOES-West, RAMMB/CIRA, The Watchers. Acquired at 21:10 UTC on March 14, 2023