What are Atmospheric Rivers? Jan 11, 2017

The heavy precipitation in California is largely in part to what’s known as an atmospheric river. These periodic surges of moisture help bring 30-50% of the West Coast’s rain every year. But what are they?

Atmospheric rivers are relatively long, narrow regions in the atmosphere – like rivers in the sky – that transport most of the water vapor outside of the tropics. These columns of vapor move with the weather, carrying an amount of water vapor roughly equivalent to the average flow of water at the mouth of the Mississippi River. When the atmospheric rivers make landfall, they often release this water vapor in the form of rain or snow.

Although atmospheric rivers come in many shapes and sizes, those that contain the largest amounts of water vapor and the strongest winds can create extreme rainfall and floods, often by stalling over watersheds vulnerable to flooding. These events can disrupt travel, induce mudslides and cause catastrophic damage to life and property. A well-known example is the “Pineapple Express,” a strong atmospheric river that is capable of bringing moisture from the tropics near Hawaii over to the U.S. West Coast.

Not all atmospheric rivers cause damage; most are weak systems that often provide beneficial rain or snow that is crucial to the water supply. Atmospheric rivers are a key feature in the global water cycle and are closely tied to both water supply and flood risks — particularly in the western United States.

While atmospheric rivers are responsible for great quantities of rain that can produce flooding, they also contribute to beneficial increases in snowpack. A series of atmospheric rivers fueled the strong winter storms that battered the U.S. West Coast from western Washington to southern California from Dec. 10–22, 2010, producing 11 to 25 inches of rain in certain areas. These rivers also contributed to the snowpack in the Sierras, which received 75 percent of its annual snow by Dec. 22, the first full day of winter.

NOAA research uses satellite, radar, aircraft and other observations, as well as major numerical weather model improvements, to better understand atmospheric rivers and their importance to both weather and climate.

Scientific research yields important data that helps NOAA’s National Weather Service forecasters issue warnings for potential heavy rain and flooding in areas prone to the impacts of atmospheric rivers as many as five to seven days in advance.

To learn more about atmospheric rivers, please visit: http://www.esrl.noaa.gov/psd/atmrivers/.

Leave a comment

Your email address will not be published. Required fields are marked *

Tweets

This was the scene today in Johnston County, NC where prolonged #rain has #flooded streets. Photo from Kiya Rice.… https://t.co/jFZaESpenA

1 hour ago by WeatherNation

Aurora Australis, the Southern Lights, light up the New Zealand skies - https://t.co/stZPIEI1LE https://t.co/q45vOTrqnb

1 hour ago by WeatherNation

What's your favorite weather day? #April25th https://t.co/zRRIvgC7pf

3 hours ago by WeatherNation

NASA Astronaut Robert Kimbrough is no Julia Child but his PB&J is still pretty stellar How to Make a PB&J in Space… https://t.co/akFRtrGXI6

3 hours ago by WeatherNation

Winter seems far from over in portions of the West and Upper Midwest with snow and ice ahead -… https://t.co/5smCw6Ttgx

5 hours ago by WeatherNation

For more information on the flooding in @RaleighGov, check here: https://t.co/Su80lSoA9V

6 hours ago by WeatherNation

Downtown @RaleighGov is seeing major flooding with a Flash Flood Emergency in place earlier Tuesday morning.… https://t.co/lfjJimwQsk

6 hours ago by WeatherNation

Happy Tuesday! A look at today's high temperatures: https://t.co/OCgepofiTU

10 hours ago by WeatherNation

Finally, a needed soaking rain in the Sunshine State. #FLwx https://t.co/8McZkuDDYd https://t.co/AZfMcvEoma

16 hours ago by WeatherNation

Heavy rain came down in #SaltLakeCity Monday. But the rain could be turning over to #Snow by the end of the week.… https://t.co/JpDEwZtTWK

17 hours ago by WeatherNation

Another dry day across #Florida. Wild fires continue to burn, but it wasn't all bad; check out these #Birds smilin… https://t.co/XNSDGhNULe

19 hours ago by WeatherNation

Flooding today in Charleston, SC. Much dryer times ahead this week. Thanks @johnorrccim . https://t.co/WEqRJ7eGxs https://t.co/VGI1tqYMQq

20 hours ago by WeatherNation

A new 90 day forecast has been issued by the @NWSCPC. It has warmer than normal weather across much of the nation… https://t.co/Jmf3QmKj1l

23 hours ago by WeatherNation

A construction crane fell into the Holston River in Weber City, VA as heavy rain fell and flooding hit the area.… https://t.co/DGkNDkik5s

24 April by WeatherNation

More than 7" of rain has fallen in parts of the Mid Atlantic, producing flooding problems. More rain ahead tonight… https://t.co/CKostOfJYa

24 April by WeatherNation

Florida Wildfires Continue to Rage With the Weather Bringing Relief to Some. Details: https://t.co/A6wbFmZ0HP https://t.co/hHaleD71Hm

24 April by WeatherNation

Heavy rains brought flooding across parts of Tennessee. This out of the Fountain City neighborhood in Knoxville. 🎥… https://t.co/PRu4RJyv6A

24 April by WeatherNation

Winter seems far from over in portions of the West and High Plains with snow continuing to fall -… https://t.co/ClPlcwmnpi

24 April by WeatherNation
Follow Us