A formidable and potentially historic atmospheric river is taking aim at the West Coast of the United States, threatening to unleash a multi-day deluge of torrential rain and destructive, hurricane-force winds. Weather officials are warning of catastrophic flooding and widespread disruption from northern California to the Pacific Northwest.
The event, known as a 'Pineapple Express' for its plume of tropical moisture stretching back to Hawaii, is forecast to be particularly severe. The National Weather Service (NWS) office in San Francisco has issued a stark warning, stating the incoming storm could be "one of the most impactful systems in recent memory."
Timeline of a Tempest
The onslaught is expected to begin in earnest on Wednesday, with the most intense conditions predicted for Thursday. The NWS has highlighted a high risk of excessive rainfall for millions of people, a warning level that is only issued on about 4% of days per year but is responsible for over 80% of all flood-related damage.
Key Dangers and Impacts
- Torrential Rainfall: California's coastal ranges and parts of Oregon could see a staggering 5 to 8 inches (12 to 20 cm) of rain, with isolated areas receiving even more.
- Life-Threatening Flooding: The heavy rain on already saturated ground significantly raises the risk of debris flows and mudslides, especially in recent wildfire burn scar areas.
- Destructive Winds: A major wind event is anticipated, with gusts potentially reaching 60 to 70 mph (95-110 km/h) along the coast and even higher speeds possible in the mountains, raising the threat of downed trees and prolonged power outages.
- Travel Chaos: Residents are urged to avoid all unnecessary travel during the peak of the storm, as road closures and extremely hazardous driving conditions are imminent.
Meteorologists are also closely monitoring the risk of thunderstorms embedded within the system, which could bring brief tornadoes and even more intense downpours to the region.
This powerful system serves as a stark reminder of the intense and disruptive weather that atmospheric rivers can bring to the West Coast. Residents across the affected regions are advised to finalise their preparations, heed all evacuation orders from local officials, and have multiple ways to receive urgent weather warnings.
