{"id":71619,"date":"2025-08-10T04:59:09","date_gmt":"2025-08-10T04:59:09","guid":{"rendered":"https:\/\/www.newsbeep.com\/us\/71619\/"},"modified":"2025-08-10T04:59:09","modified_gmt":"2025-08-10T04:59:09","slug":"atmospheric-rivers-may-be-diminishing-on-the-west-coast-and-surging-in-the-east-study-finds","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/us\/71619\/","title":{"rendered":"Atmospheric Rivers May be Diminishing on the West Coast and Surging in the East, Study Finds"},"content":{"rendered":"

It makes sense that atmospheric rivers would flood West Coast headlines as well as its coastlines. Eighty percent<\/a> of all West Coast flood damage is attributable to these immense highways of water vapor, which can drench Central California with a season\u2019s worth of rain<\/a> or freeze Seattle in place with a blizzard<\/a>. Damages to Pacific states from the surges of precipitation can add up to about a billion dollars annually<\/a>.<\/p>\n

But what about East Coast atmospheric rivers?<\/p>\n

The daughter of former NOAA research scientist, Wenhao Dong, posed that exact question to her father when she was in first grade.<\/p>\n

\u201cShe was listening to the report about an atmospheric river over California,\u201d he recalled. \u201cShe asked me, \u2018Dad, do we have atmospheric rivers [in New Jersey]?\u2019\u201d<\/p>\n

That question partly motivated Dong and his collaborators to investigate how atmospheric rivers might be impacting the East Coast and West Coast differently. In a study published earlier this year in Nature that looked at 40 years of water vapor, precipitation and wind speed observations, Dong and his co-authors found that<\/a> wintertime atmospheric rivers are growing significantly more frequent and intense over the Eastern U.S. while diminishing over the West. Their research showed that, over a 20-year period, atmospheric rivers could double the amount of rain falling in parts of the Southeast.<\/p>\n

And while they might not produce as many headlines, East Coast atmospheric rivers are far from forgettable. One that hit New England at the end of 2024 left over 80,000 homes without electricity<\/a>. But research into the phenomenon in the Eastern U.S. is limited. More than three-fourths of all atmospheric river studies focus on either the Western U.S. or Western Europe, Dong said. That bias makes sense because atmospheric rivers are the West\u2019s grand rainmakers, while hurricanes, large thunderstorms and Nor\u2019easters dominate at least the news about Eastern weather. But the two coasts\u2019 big storms might have more in common than the headlines suggest.<\/p>\n

\u201cWhen you look at the data\u2014the precipitation contribution from [atmospheric rivers]\u2014you will see comparable contributions over the West and the Eastern U.S.,\u201d Dong said.<\/p>\n

\"\"<\/p>\n

Dong\u2019s team found that between 1980 and 2020, atmospheric river frequency over the Eastern U.S. increased by almost five percent each decade, with the storms slamming the South particularly hard. Parts of Mississippi, Alabama and Tennessee saw average atmospheric river rainfall rates increase by as much as two millimeters per day per decade over the last 40 years. With average daily precipitation in Mississippi being about 3.9 millimeters per day<\/a>, if this trend continues, atmospheric rivers could double the average rainfall in some parts of the state in 20 years. Extreme rainfall rates in parts of Georgia have risen by almost four millimeters per day per decade, according to the study.\u00a0<\/p>\n

In the meantime, states such as Washington, Oregon and California have seen atmospheric river frequency decrease by nearly 4 percent per decade since 1980, the researchers found. This has led to long-term wintertime drying of the West Coast. Portland, Oregon, for example, has seen its average atmospheric river rain rate decrease by over two millimeters per decade. Its average daily rainfall over the past 20 years has been just over 2.5 millimeters<\/a>. While the West is drying out overall, there is an increase in extreme precipitation events that are associated with catastrophic atmospheric rivers, Dong added.<\/p>\n

\"ClarksvilleClarksville Fire Rescue members perform water rescues to evacuate people trapped during intense flooding after heavy rains on Feb. 16 in Clarksville, Tenn. Credit: Clarksville Fire Rescue via Getty Images<\/p>\n

Forming a river in the atmosphere requires tropical water vapor sources, jet streams to push that moisture and favorable regional weather conditions such as low-pressure systems. Dong and his colleagues investigated these and other background atmospheric and oceanic conditions, which can change on seasonal, annual or even longer timescales to transform atmospheric river patterns.\u00a0<\/p>\n

This study looked at a handful of changes to these \u201cmodes of variability,\u201d including more common La Ni\u00f1a-like, or colder, temperatures in the Pacific and variations in the location of the East Asian Subtropical Jet Stream, to determine what was happening to atmospheric rivers. Modes of variability often work in tandem\u2014two or three overlapping at a time\u2014to impact atmospheric rivers by changing the intensity of atmospheric circulations in the East Pacific and tropical Atlantic. For example, warm waters in the Eastern Pacific during an El Ni\u00f1o year could change the location of the East Asian Subtropical Jet Stream, leading atmospheric rivers to hit Los Angeles instead of Seattle.\u00a0<\/p>\n

Long-term changes in these modes of variability are bringing dry, cold air down from the Arctic to dry out the East Pacific, cutting off the flow of tropical, moist air that would drive atmospheric rivers to the West Coast. This is bringing a measured decline in atmospheric river frequency in California, Oregon and Washington.\u00a0<\/p>\n

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The Eastern seaboard is seeing a bit of the opposite, the researchers found. Changes in the Atlantic are bringing warm, moist air out of the Gulf of Mexico, increasing the formation of atmospheric rivers. But while the decades of change that make one region drier and another one wetter might seem like human-driven climate change at work, the study authors hesitate to go that far.<\/p>\n

\u201cWe do not understand how the natural modes of variability are getting affected by the broad global change,\u201d said Venkatachalam Ramaswamy, director of NOAA\u2019s Geophysical Fluid Dynamics Laboratory and a study co-author. Most continuous records of weather observations only go back into the 1950s, so \u201cwe don\u2019t really have necessarily a comprehensive picture of the changes in atmospheric circulation, \u201d he added.\u00a0<\/p>\n

Because some of the modes of variability oscillate very slowly\u2014over years or even decades\u2014hundreds of years of observations might be needed to definitively demonstrate that outside factors, like human impacts on the climate, are causing the observed changes.\u00a0<\/p>\n

The different ways researchers determine if a circulation of wet weather is an atmospheric river\u2014the amount of moisture, its persistence, how it\u2019s transported and the size and the shape of its flow\u2014means different observers get varying results, said Christine Shields, Project Scientist at the National Center for Atmospheric Research.\u00a0<\/p>\n

She\u2019s cautious about some results about East Coast atmospheric rivers. \u201cA lot of these detection algorithms, and I would say, especially the global ones, may pick up things that you might not consider [atmospheric rivers],\u201d she said. For instance, some \u201cblobby\u201d flows of water vapor, particularly those coming from the Gulf of Mexico, could have the \u201cmassive signal\u201d and statistical significance to be atmospheric rivers in the new study, but not be viewed as such by many other researchers, she said.<\/p>\n

But the study\u2019s approach to measuring the relationship between modes of variability and the changes in atmospheric rivers is still robust, she emphasized.<\/p>\n

And understanding how much of the increase in rainfall over the East Coast is coming from atmospheric rivers\u2014regardless of how they are defined\u2014can be important to some stakeholders. Knowing how much rain could surge from an atmospheric river is valuable information for water resource managers who need to manage both drinking water and flood risk concerns, Ramaswamy noted.\u00a0<\/p>\n

\t\tAbout This Story<\/p>\n

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Thank you,<\/p>\n

\t\t\t\t\t\"\"<\/p>\n

\t\t\t\t\t
\n\t\t\t\t\t\tChad Small\t\t\t\t\t<\/a><\/p>\n

\t\t\t\t\tFellow<\/p>\n

Chad Small is the 2025 AAAS Mass Media fellow with Inside Climate News. He is a third-year PhD student in Atmospheric and Climate Science at the University of Washington. Chad currently researches how information about tropical phenomena can improve our understanding of extreme rainfall and flooding events in both tropical regions and midlatitude regions, like the United States. Originally from New York City, he has also written as a freelance journalist with work appearing in the Bulletin of the Atomic Scientists, Grist, Imagine5, Next City and elsewhere. Most recently, Chad has been the Climate Change Editorial Fellow at the Bulletin of the Atomic Scientists.<\/p>\n","protected":false},"excerpt":{"rendered":"It makes sense that atmospheric rivers would flood West Coast headlines as well as its coastlines. Eighty percent…\n","protected":false},"author":2,"featured_media":71620,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[47],"tags":[192,79],"class_list":{"0":"post-71619","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-environment","8":"tag-environment","9":"tag-science"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/71619","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/comments?post=71619"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/71619\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media\/71620"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media?parent=71619"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/categories?post=71619"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/tags?post=71619"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}