The term “atmospheric river” isn’t new, but the phrase is making the rounds online because the weather forecast for Northern California is so active. Here’s what you need to know about these unique storm systems. What is an atmospheric river? An atmospheric river is a long, narrow band of tropical moisture that is transported into the middle and upper parts of the atmosphere. These “rivers in the sky” can transport significant amounts of water vapor from tropical regions near the equator to midlatitude locations such as northern California. As these systems move over land, they can produce extreme rainfall rates and strong winds. Cold atmospheric river systems can produce significant snow at high altitudes. Are all Northern California rain events atmospheric rivers? No! By definition, these storms form in the tropics where there is more moisture in the air. Systems from areas farther north are often less humid and are not considered atmospheric rivers. According to NOAA, atmospheric river storms, on average, account for 30% to 50% of the annual rainfall on the US West Coast. 2022-2023 rainfall and snow season will be above average. This week’s storm will bring gusty winds and heavy rain with scattered showers Thursday afternoon through Friday afternoon. Temperatures with this storm are on the high side, meaning snow levels will rise as the storm moves through. Expect snow levels around 4000′ due to rain on Thursday. Snow levels will rise above 6000′ by Thursday night. High passes may see snow throughout this storm, which could cause travel problems for those trying to get over the mountains. Rain and warmer temperatures can cause rapid snowmelt in areas below 5,000 feet. Flooding is likely in low-lying areas. Creeks and streams should be carefully monitored. As of Wednesday afternoon, the Cosumnes River, Tuolumne River and Mogelumne River are forecast to rise above flood stage by Friday afternoon. More storm coverage Check storm and travel updates Share the latest forecast Share your weather video Check the latest chain restrictions and road conditions See our latest news Check school closings See a list of sandbag locations How to sign up for emergency alerts Report outages What are the current power outages Download our app | Track Doppler Radar | Real-time traffic map
The term “atmospheric river” isn’t new, but the phrase is making the rounds online because the weather forecast for Northern California is so active.
Here’s what you need to know about these unique storm systems.
What is an Atmospheric River?
An atmospheric river is a long, narrow band of tropical moisture that travels along the middle and upper parts of the atmosphere.
These “rivers in the sky” can transport significant amounts of water vapor from tropical regions near the equator to midlatitude locations such as northern California.
As these systems move over land, they can produce extreme rainfall rates and strong winds.
Cold atmospheric river systems can produce significant snow at high altitudes.
Are all Northern California rain events atmospheric rivers?
No!
By definition, these storms form in the tropics where there is more moisture in the air.
Systems from areas farther north are often less humid and are not considered atmospheric rivers.
According to NOAA, atmospheric river storms, on average, account for 30% to 50% of the annual rainfall on the US West Coast.
2022-2023 rainfall and snow season will be above average.
Storm this week
Strong winds and heavy rain are possible starting Thursday afternoon, with scattered showers continuing through Friday afternoon.
Temperatures with this storm are on the warmer side, meaning snow levels will rise as the storm moves through.
Expect snow levels around 4000′ due to rain on Thursday. Snow levels will rise above 6000′ by Thursday night.
High passes may see snow throughout this storm, which could cause travel problems for those trying to get over the mountains.
Rain and warmer temperatures can cause rapid snowmelt in areas below 5,000 feet. Flooding is likely in low-lying areas. Creeks and streams should be carefully monitored.
As of Wednesday afternoon, the Cosumnes River, Tuolumne River and Mogelumne River are forecast to rise above flood stage by Friday afternoon.
Also storm protection
