More recently, another rare snow event occurred in San Francisco on February 12, 2025, when an atmospheric river approached the continent. The accumulation of snow is rarer to see in San Francisco than in New Orleans or the Florida Panhandle. The reason this event was so rare is because this region is influenced by the California current which creates one of the most stable climates in the world where temperature inversions are highly common, and air pollution becomes trapped almost constantly. This is important to note because in the middle of February, just two days ago, even the world’s most stable climate showed vulnerability to modern climate change.
Atmospheric rivers are a natural phenomenon that existed in the atmosphere before anthropogenic climate change became a real problem, but we can expect AR events to be more common and extreme as the global temperature continues to rise. Satellites operated by NOAA track the movement of water vapor in the AR’s and results show that 30 – 50% of annual rainfall for west coast states comes from AR precipitation. Presently there are 4-5 atmospheric rivers on Earth. According to NOAA, a category 5 AR is estimated to contain 7-15 times the amount of water that flows from the Mississippi River into the Gulf of Mexico in one day.
The atmospheric river that hit San Francisco this month was a level 3 AR event with no fatalities reported. A lead author scientist from NASA’s Jet Propulsion Laboratory, Duane Waliser has projected that by the end of the 21st century, there will be 10% less global AR event but are also projected to become 25% wider and longer on average with global AR conditions also increasing by about 50%. It is helpful that AR events occur for recharging aquifers and river systems, but it is the unpredictability and dangerous amount of water that also occurs with this growing phenomenon that could lead to deadly floods and ruin crop yields.
In an aerial view, floodwaters surround homes and farms on November 20, 2021 in Abbotsford, British Columbia.
I have been really curious on learning more about these mysterious snowstorms. It takes time for us to acclimate to different temperatures, as I think this was mentioned in nomad century. Thinking about being in a warmer area that never gets snow I can’t imagine the lack of understanding and unpreparedness those people must have felt.
ReplyDeleteI am always excited to read your blog posts. It' so interesting to see climate change from this perspective.
ReplyDeleteThank you Liz!
DeleteThe connection between AR events and water supply is very interesting, and the potential for flooding is really concerning. I did not know that the California current creates one of the most stable climates in the world. The unpredictable weather is definitely scary!
ReplyDeleteClimate change is rapidly changing the world around us and effecting usually stable climates. Places that are not use this weather are unprepared for the change in climate.
ReplyDeleteBefore a few years ago, I hadn't heard of atmospheric rivers. While they almost certainly have happened in the past, it seems like their intensity is increasing like you mention. Which is definitely in line with what our knowledge of climate change effects is. We should be making efforts to adapt to the reduced frequency and increased intensity of precipitation events all around.
ReplyDeleteIt is kind of crazy how much the climate has changed and people are now experiencing weather like they have never before.
ReplyDeleteReading about all of the southern states flooded due to snow while kentucky is also flooded due to heavy rains is wild. Now i hear them discussing tornadoes soon, i feel like it is a bit early for tornadoes in the year. But this all ties together, the weather events are happening with harsher effects and more sporadically. You brought up a lot of great points!
ReplyDeleteI had never heard of atmospheric rivers before so this was a really interesting and informative post for me! However, it is disheartening to hear about another climate disaster affecting the southern coast. It seems like every year these areas become more and more unstable and makes me wonder how much longer people will be able to live in these areas.
ReplyDeleteAs atmospheric rivers are projected to become wider and more intense, the potential for devastating floods and agricultural disruption underscores the urgent need for adaptive strategies to manage these evolving climate challenges.
ReplyDeleteThis was a great post something that stood out to me the most was the fact that the deadly amount of water could ruin crops and if the crops and fields are ruined how are some people going to get food it could turn into a big problem.
ReplyDeleteI have heard very little about atmospheric rivers, and it's alarming to see predictions of their coming frequency. This overwhelming amount of water cannot be contained, and damage mitigation efforts should be invested in ahead of time as to not wait for disaster to strike.
ReplyDeleteI've never heard of atmospheric rivers before. Perhaps I am a bit scientifically adverse but I am still struggling to understand what they are? Is it simply a specific altered flow of air that influences precipitation?
ReplyDeleteHey Michael, really interesting post! Crazy to see places like San Francisco getting snow. With ARs getting stronger, do you think we’re ready for the flooding risks? Would love to hear your thoughts!
ReplyDeleteHey Yusuf, great question and thank you for asking! My instinctual answer is no, because the patterns of the AR’s and the amount of precipitation that will occur are only predictions, so far. Also tracking the atmospheric rivers and other major storm systems is also only one part of the risk prevention. In the future I think we will be collecting and storing AR rainfall for drinking water and agricultural use but right now the events are mostly leading to negative outcomes.
DeleteHowever, we are seeing insurance companies denying coverage in flood prone areas so there are researchers and legal corporations that are taking flood risk very seriously and trying to be ready. Thanks for the question Yusuf!
This is a pretty cool post, I didn't even know that atmospheric rivers were a thing until now. The statistic about them carrying more water than 7 to 15 times the amount that flows from the Mississippi is wild.
ReplyDeleteI had no idea about the role of atmospheric rivers in the severe and "out of place" snow storms that we have been having, such as the ones that brought record-breaking snowfall in places like Florida. It must be terrifying for the people living in these areas to face such climate disasters.
ReplyDeleteThis was really cool to learn about. I wondered about events like these
ReplyDeleteI have never heard of the phenomena of atmospheric rivers so I am really intrigued reading your post. It is insane how climate change deniers are so quick to discredit climate change due to these freezing conditions, but that is only a factor of the damage that is to come.
ReplyDeleteThis was a very interesting read. I had never heard of Sky Rivers before, and I appreciate all the details. I wonder if there will be more links between flooding and flash floods. Climate change also seems to play a devastating role in atmospheric control.
ReplyDelete