California Declares State of Emergency as “Pineapple Express” Storm Approaches

A powerful winter storm, bringing gale-force winds and heavy rain, is hitting California and is expected to cause flooding, mudslides and rock slides in some areas due to the heavy snowpack.[0] The state’s governor, Gavin Newsom, has declared a state of emergency for 21 counties, including mountain communities still digging themselves out from the snow.[1]

The storm, classified as an atmospheric river, is made up of a long, narrow band of wind that transports warm water vapor from the tropics.[2] This is known as a “pineapple express” because of its origins near Hawaii.[3]

The rain is expected to be heaviest in central California, with some mountain areas above 8,000 feet expected to see heavy, wet snow.[4] Creeks and streams in the foothills of the Sierra Nevada are forecast to be the most vulnerable to flooding from rain and snowmelt.[2]

Evacuation warnings have been issued in parts of Fresno, Tulare, Madera, Mariposa, Santa Cruz, Monterey and Merced counties. The City of Merced has issued evacuation warnings for several areas as the storm moves in.

The rain is expected to arrive Thursday afternoon and continue into the middle of next week, with strong southerly winds developing Thursday afternoon to Friday afternoon, with gusts up to around 50 mph.[5] The Bay Area and California’s Central Coast could receive up to 3 inches of rain through the weekend, while the Santa Cruz mountains may receive up to 7 inches.[3]

In the South Bay, 2 to 3 inches of precipitation is predicted, whereas the coastal hills of the North Bay may receive 5 to 6 inches.[6] In the Sierra Nevada mountains, heavy snow is expected at higher elevations, while towns at lower levels may see flooding as rain washes away recent snow.[7]

Flooding of roadways, rivers, creeks, streams, and other flood prone areas is possible, especially in areas that have poor drainage due to the snow blocking drains and culverts.[8] Some ski resorts in the Lake Tahoe area have closed due to high winds and avalanche concerns.[9]

In total, approximately 16 million individuals are under flood warning advisories.[10] Residents in affected areas are advised to stock up on supplies and sandbags.[10]

0. “Track California’s Latest Storm” The New York Times, 10 Mar. 2023,

1. “San Diego to Get Leftover Rain From Atmospheric River Pounding Northern California” NBC San Diego, 11 Mar. 2023,

2. “Atmospheric rivers hit California with heavy rain and snow” NPR, 11 Mar. 2023,

3. “California braces for more flooding as another winter storm nears” Al Jazeera English, 9 Mar. 2023,

4. “Atmospheric River-Fed Storm Pummels California |” The Weather Channel, 7 Mar. 2023,

5. “These California rivers may reach above flood level during the upcoming winter storm” KTXL FOX 40 Sacramento, 9 Mar. 2023,

6. “Bay Area storm watch: atmospheric river is here, what to expect” KTVU FOX 2 San Francisco, 8 Mar. 2023,

7. “Parts of California face ‘flooding emergency' as storm kills at least 2” The Washington Post, 10 Mar. 2023,

8. “Bay Area Weather: Atmospheric River to Bring Heavy Rain, Gusty Winds, Possible Thunderstorms” NBC Bay Area, 10 Mar. 2023,

9. “Atmospheric river storm brings headaches, traffic jams and wet weather, but Bay Area escapes severe damage” Red Bluff Daily News, 11 Mar. 2023,

10. “California declares state of emergency as subtropical storm moves over state” The Guardian US, 10 Mar. 2023,