Super El Niño, Kelvin Waves, and California
“Very strong El Nino events tend to generate multiple Kelvin waves over their life cycle that eventually make it to California. And if El Nino is strong enough, they can substantially elevate the coastal ocean height— essentially inducing a temporary months-long sea level rise that can have significant impacts along the California coast”
A conversation with Daniel Swain (University of California Agriculture and Natural Resources) about the Super El Niño's impacts in California including coastal impacts and preparedness strategies. Released November 13, 2026.
guests on the show
Daniel Swain
Daniel Swain is a weather and climate scientist focused on the dynamics and impacts of extreme events—including droughts, floods, storms, and wildfires—on a warming planet. His primary appointment is as a climate scientist (Associate Researcher) in the California Institute for Water Resources within University of California Agriculture and Natural Resources (UCANR), and has been a longtime research partner at the NSF National Center for Atmospheric Research. He engages extensively with journalists as a recurring expert source—averaging over 200 interviews per year across hundreds of news outlets—helping make extreme weather, climate change, and associated natural hazards accessible and accurate in public discourse.
Daniel is an alumnus of the University of California, Davis (B.S., Atmospheric Science) and of Stanford University (Ph.D., Earth System Science), and completed his postdoctoral work at UCLA. He also authors the widely-read Weather West blog (weatherwest.com), which provides real-time perspectives on California weather and climate, and can be found on YouTube (@WeatherWest), Bluesky (@WeatherWest), Twitter/X (@Weather_West), as well as other social media platforms. His publications can be found via Google Scholar and ORCID
TRANSCRIPT
Faith Kearns
Hi, Water Talk listeners. Today we are talking about El Niño and specifically the impacts of El Niño in California. And in terms of the ideas that come up during the episode, I think obviously just defining El Niño again is something to look out for. I hope that by the end of this cycle of El Niño, I really will have a definition right at hand anytime I would like it. And I think the other thing that comes up pretty strongly in this episode to think about is this idea of a compound hazard.
So, you know, the impacts of El Niño are somewhat difficult to predict, but in coastal areas, particularly the California coast, the western U.S., I think in general, there are already hazards that exist. So, king tides can raise the sea level. And then there's also just background sea level rise. And then there's also water that potentially is coming down from rivers and streams to the coast. And so, you can imagine this collision of a whole bunch of water coming both from the ocean and toward the ocean and how that might play out in certain places.
And so, one of the things that folks are particularly worried about in California this year is compound coastal flooding impacts due to the particular way that El Niño plays out in addition to other high tide issues. What about you, Mallika? Are there things that you think listeners should be attuned to?
Mallika Nocco
Yeah, I always think it's interesting when we start to think about a warmer, wetter winter in California and what that means for the hydrology of California and similar western states. So, I think you can apply this to western states that are using snowpack as a reservoir. But you know, we've talked about it related to climate change.
And then in this episode, we're going to talk about it related to El Niño. And it's this idea that like what happens when you have rain versus snow in the winter in California? Where does it go? Does it, you know, if you have rain, it's not going to get stored in that snowpack reservoir. How else can we consider capturing the rain? And how are we thinking about the hydrology? Like, what does that mean for our overall hydrology and reservoir operations and things like that? So, I really love thinking about those connections. And again, this is another episode where we're going to start to think about those connections in that Mediterranean context.
Faith Kearns
So, without further ado, let's go ahead and get right into our interview with Daniel Swain.
Welcome to Water Talk. For today's episode, we are going to be talking about El Niño and what a potentially historic event could mean for California's winter with Dr. Daniel Swain. Daniel is a climate scientist and science communicator focused on the dynamics and impacts of extreme events, including droughts, floods, storms, and wildfires on a warming planet.
Daniel holds joint appointments as a climate scientist within the California Institute for Water Resources in the University of California's Ag and Natural Resources, and as a research partner at the NSF National Center for Atmospheric Research. He also authors the widely read Weather West blog, which provides real-time perspectives on California weather and climate and can be found on pretty much every social media platform, including a popular YouTube channel.
So, Daniel, welcome back to Water Talk. It's been a little while. I think we're in our seventh season, and you were with us during our first. So, we thank you for that. And thank you for return being a returning guest.
Daniel Swain
Thanks for having me back. And it's great to be here now as a member of UCANR as well.
Faith Kearns
Yeah, it's super exciting. Now you're a colleague and not just a guest. I mean an institutional colleague, I should say. Daniel and I are now working together in the same institution for the first time. So exciting times.
You are the California El Niño expert. And so, we're going to start with just the basics. I can never personally hear this enough times, describing what is El Niño? And what the heck this Kelvin wave thing has to do with anything? And where are we in this event right now? And why are forecasters saying this could really rank as one of the strongest El Niño on record?
Daniel Swain
Yeah, you know, El Niño is both something that is fundamentally important in the global climate system and also probably the subject of more misunderstandings and misconceptions than you could possibly imagine. So, I do think it's worth always starting out with a quick overview of just what El Niño is and also what it isn't. And what it is, is essentially just this episodic warming of the eastern equatorial Pacific Ocean. That is El Niño by definition. It's not a storm or rain, it isn't even really something that happens that close to California.
El Niño is a process that unfolds in the tropical Pacific Ocean, west of the Galapagos Islands, thousands of miles away from California, when that patch of ocean is significantly warmer than average, and it is part of a truly natural climate cycle, the broader term for which is the El Niño Southern Oscillation or ENSO is the acronym.
La Nina is the cool counterpart, although I won't say it's El Niño's opposite for a variety of reasons, including geophysical ones, but essentially La Niña is the cool phase of this natural oscillation, and El Niño is the warm phase. And as you might expect, El Niño and La Niña can have a wide range of intensities and impacts.
And right now, the reason why everybody is so excited about this particular event is that it is already essentially tied for the strongest using the most conservative available metric, or already the strongest on record using other metrics that we've seen in at least since the 1950s. There was a stronger one in the 50s, it just means we don't have clear records to distinguish prior to that point. So, you know, we're already in rare to unprecedented territory as it stands today.
And the Kelvin wave, this term that's been bouncing around newspaper headlines and social media graphics, including some egregious ones that show like a tsunami like wall of water heading for LA or something, which to be very clear, it does not characterize a Kelvin wave in any way, shape, or form. I've been kind of my line has recently been that Kelvin waves are both a lot more subtle and a lot more important than you think they are, in the sense that, you know, in the dimension that we often think about ocean waves, which is the vertical dimension, how tall is the as a crusting wave at the beach, you know, the breakers, the people surfing waves, or the giant waves that are smashing against the coastal bluffs or something, it's not that kind of wave. It's only really at its absolute maximum, about 18 inches high.
And so, you might say, okay, so what's the big deal? Or something that's you know maybe knee height on some people and usually below. I think the key aspect of a Kelvin wave is that what it lacks in vertical amplitude, it has in in width and duration. So, it probably is more useful to think of an oceanic Kelvin wave as a bulge in the ocean surface height rather than a wave. It is technically a wave because it's cyclical and it has sort of a mathematical structure known as a sinusoid. But really, what it is a bulge in the height of ocean water that's anywhere from about six inches if it's a small one to about 18 inches if it's about the strong as they can get.
And we're in that territory now with the Kelvin wave that just arrived and sort of was passing through California's coastal regions, it is in that in that 12-to-16-inch range. It's getting up there as about as high as they ever get. And the reason why we're talking about it so much right now is that very strong El Niño events tend to generate multiple Kelvin waves over their life cycle that eventually make it to California. And if El Niño is strong enough, they can substantially elevate the coastal ocean height, essentially inducing a temporary months-long sea level rise that can have significant impacts along the California coast.
And the physics of how these things form are complicated. We can get into them because it's kind of fascinating, but it is a remarkable reflection of the fact that what's happening, you know, in the distant tropical Pacific Ocean, literally thousands of miles from California, in the case of Kelvin waves, they form, you know, in this in the central tropical Pacific, which then propagate east to the coast of South America, and then they go both north and south along the coasts of the Americas, both in the northern and the southern hemisphere.
So, it's an incredibly sort of a daisy-chained Rube Goldberg machine type process, depending on your generation is maybe the right the right analogy to use there about this this this interactive chain of loosely connected events that results in a fairly you know noticeable outcome along the California coast.
Faith Kearns
And so, I think area-wise, I get what you're saying, height-wise, but t sounds like these Kelvin waves then area-wise are also very large. Or do they not have to be?
Daniel Swain
Yes, and thank you for that. I kind of skipped over that part in my in my haste to get to the to the Rube Goldberg analogy. I think, as we've been talking about these Kelvin waves are on the order of a foot tall, maybe sixteen inches tall, something like that. But they can be hundreds of miles wide. So, the total volume of water involved is very large, and they move slowly, unlike a breaking ocean wave, which you might see coming, it arrives and it dissipates over the course of maybe 30 seconds, right?
A Kelvin wave is by the time it's moving up the coast in what's known as a coastally trapped form, it kind of hugs the coast, a really narrow width of ocean distance from the coast, just a couple of miles, really, is this whole thing is contained in, but it can extend along hundreds of miles of coast, even though it only extends a few miles out. And so, you know, these waves, once they start moving up and down the coast of the Americas in their coastally trapped form, they're only moving at about a slow jog speed, like six miles an hour or so.
So, you could, in theory, outrun, outrun a Kelvin wave, but to do so, you'd have to keep that slow jog pace all the way from the beaches of Peru all the way north to Southern California without stopping for several weeks. So, I doubt anybody has ever tried. But, you know, because they're slow moving and because they're several hundred miles wide, it takes weeks for the peak of one of these waves to pass a particular point. So, it results in very prolonged elevation of that ocean level.
So, it isn't just a quick little rise that recedes, it's an elevation in sea level that persists across many high and low tide cycles, across multiple potential storm systems. And so, in so doing, it doesn't need to be exactly aligned with any particular high tide or any particular storm. They're so persistent that whenever you do get a particularly high tide or significant storm, that elevated sea level is there and waiting to potentially cause some inundation.
Faith Kearns
Okay, so the Kelvin wake can somewhat compound potential El Niño impacts, I think, is what I'm understanding.
Daniel Swain
Yes, it can both compound them and is itself one of El Niño's impacts. So, El Niño through various processes is what generates these Kelvin waves in the first place. And so, we get the 6, 12, maybe 14, 16-inch elevation in sea level from the Kelvin wave, and we usually get at least two or three of them during a big El Niño event. We might get as many as four or five this year. We're sort of in number one now, so we're just at the beginning here.
But also, El Niño is warming these near shore ocean temperatures off the coast of California. So even though El Niño is defined based on how warm the tropics are, thousands of miles away, a big event does tend to warm the near shore waters right along the California coast, too. And if you've been anywhere on the beach, anywhere south of about Mendocino County in the last couple of weeks, you may have noticed that it is conspicuously balmily warm. We have water temperatures closer to 80 than 70 Fahrenheit in Southern California waters right now. We have water that's almost 70 degrees getting up toward Monterey Bay right now. So that's very warm water for the Central Coast.
And that has additional implications for coastal communities. Obviously, it has large ecosystem impacts because of the disruption to ecosystems from this prolonged marine heat wave. Species are not used to that level of persistent heat, and it means that species are sort of coming in from elsewhere because of the shifted currents and the warmer water, seeing some more subtropical species show up on the beaches, but also because that warm water also causes thermal expansion. So, water being warmer than it usually is on top of the Kelvin wave means that it gets even higher because it literally takes up more space. The volume of a given amount of seawater is greater when it is warmer. So we kind of stack these things. We start stacking these things.
Our colleague at UCANR, Christina Richardson, has a great visual showing this stacking effect where we have, you know, lurking in the background is long-term sea level rise from global warming. That's six to maybe 10 or 12 inches, depending on where you are along the California coast. And then we've got the thermal expansion from this extreme marine heat wave, which right now is close to a foot. So it's actually not, you know, it's comparable to sea level rise in its own right. And then on top of that, we have the effects of the Kelvin wave, which are on the order of a foot or more.
So depending on exactly how we count the math and the stacking between sea level rise and the direct and indirect effects of El Niño through the Kelvin wave processes and the thermal expansion, we're you know, sort of sitting potentially between about a foot and a half and three feet of temporary sea level elevation this year, which, you know, we talk about long-term sea level rise over decades, and it's on that order. So, you know, we're seeing a lot of it suddenly all at once right now along the California coast.
Faith Kearns
And just in terms of you know, the sort of super El Niño terminology, why is that used this year? I mean, it's so hard to keep track of like Godzilla this and super that and whatever. And so, I'm just like clarifying what the super El Niño for this year really means.
Daniel Swain
Yeah, it's kind of funny. You can trace back some of these superlatives to specific sources, like their first usage in a particular context on the internet somewhere, and you can kind of see where it went viral for better or for worse from there. Super El Niño is a term that has been around for a while. It doesn't have a formal quantitative scientific definition, but it's one that I'm not bothered by it, I think, in the same way that some meteorologists and climate scientists have professed to be before, mainly because it is intended to connote that literally, in this case, superlative, meaning that it is it is beyond some reasonable range. In this case, it literally means beyond strong.
And so you can kind of it's quasi-equivalent with the official NOAA federal government definition of a very strong El Niño event, being one that significantly exceeds strong, as you might expect, and usually is defined to mean about two degrees Celsius, or about, I think that's about 3.8 degrees Fahrenheit or so, warmer than average water in the eastern tropical Pacific Ocean, which may not sound like a lot, but you know, it takes a lot of energy to heat that vast volume of the tropical ocean by even a degree.
So, once you start getting into the multiple degrees territory, that's above that two-degree number, we're kind of in rare territory. So really Super El Niño just means at the upper echelon of what we've observed historically. And Godzilla means even less specifically, you know, some it was really a term coined, I think, by one Southern California climatologist.
Mallika Nocco
Oh, I thought people were joking about Godzilla.
Daniel Swain
People are saying Godzilla in California about this, or just not heard Godzilla El Niño climate scientists back in about 10 years ago, and it kind of took off from there. I don't personally use that term. I will occasionally throw in super just because it's so widely used, and it does have a quasi-quantitative definition. So, I guess I drew the line at super, and between super and Godzilla, maybe.
I think you know, this year, though, I mean, is a good example of okay, clearly, we're in super territory or very strong territory, as Noah Wood is calling it. But arguably this year's event is already so beyond by some metrics what we've seen before. And interestingly, no matter what metric we use, even the most conservative ones, it's actually expected to become by a significant margin the strongest on record, which is really quite notable. Maybe we do need a term to describe the anomalousness of something like this to distinguish it from merely strong, because we really are in territory that we just haven't really seen before or are certainly headed there.
I think we sometimes have this challenge in a changing world, in a warming world where we do see events that are significantly beyond the historical envelope of conditions we've experienced before. And so, what language we use to describe that, I do think becomes important. And, you know, I'm somebody who thinks a lot about the specific language I use, you know, in having these conversations. And I think we are at that point where, you know, like I'm calling it an extreme El Niño event or a record-breaking El Niño event because those are like grounded in actual statistics. But, I'm not going to deny anybody their super El Niño. I far be it from me.
Mallika Nocco
So, to shift gears a little bit, Daniel, you've said that you have very high confidence in there being a wetter than average California winter with the biggest signal in January and February. What's driving your confidence and what is still genuinely uncertain? Like, you know, spatial trends and patterns like north versus south, or just the timing of big storms, or where is the uncertainty?
Daniel Swain
A lot of this comes from, you know, this level of confidence, which by the way, is very unusual for California seasonal prediction. We often have low confidence, or maybe you could say no confidence in what the coming winter might hold. There often isn't very much predictability.
But, you know, as a physical climate scientist, as a meteorologist, as an atmospheric scientist, by the way, those are more terms that I use almost interchangeably because I wear slightly different hats on slightly different days. Um, and I'm going to extend this hat metaphor, just bear with me here. But then, you know, this event really is so intense. It is so overwhelmingly intense that it's almost certain that it will be the dominant global influence on climate this winter, aside from human-caused climate change, which is always there now, lurking in the background. But aside from that, I mean, this is a really profound temporary shift in the system.
And there really isn't anything else like a very strong El Niño event, Super El Niño, extreme El Niño, whatever you want to call it, in terms of its relative influence on global climate on seasonal scales. There really isn't any other even conceivable factor short of some, you know, geophysical global catastrophes that I won't dwell upon here. But short of that, something really cataclysmic, a really big El Niño event is the biggest kick to the climate system we can give it on short timescales. So, A, this event is extremely intense and will probably be the strongest we've ever seen. But B, you know, you might say, well, okay, 2015-2016 was at the time also the strongest El Niño event we've we had seen at that point in history, and it was not a particularly wet winter in California. I would note that it was also not a dry winter, but it definitely wasn't unusually wet, as was the forecast for a strong tilt in the odds towards a wet winter, which did not materialize.
One thing to recognize is that these kinds of predictions are always probabilistic, meaning that they, you know, we can't say ever with certainty what's going to happen in a given region in a given season. We can at best give a sense of what the tilt and the probabilities will be. Sometimes they're subtle, sometimes, in rare cases, they're rather profound, like I would argue they are this year. But in retrospect, it turns out that there were a few indications that 2015-2016 probably we should have anticipated that it did not have as elevated a likelihood of a wet winter as we thought at the time.
This is partly because the science has advanced. It's also partly because looking backward is usually easier in retrospect than looking forward because you know what your signals, you're trying to look for. But the other thing that's going on this winter is that the spatial pattern of this El Niño event is also much more favorable for a higher confidence prediction regarding the winter. So not only is it essentially the strongest El Niño event we've ever seen, but it is also the most eastern-centered that we've ever seen. So it's actually breaking superlatives both in terms of its intensity and its position, and both would favor an even higher confidence of an even wetter winter this year, putting it really more into the territory of the kind of El Niño events we saw in 1997, 1998, or 1982, 1983, but with 30 to 40 years of global warming on top of it, warming ocean temperatures even more, accelerating the hydrologic cycle by another 10 or 15% on top of those events.
That's kind of my mental model is 97, 98 like, 82, 83 like, but possibly with a higher ceiling in terms of coastal flooding and rain risk. And, you know, those were very substantially impactful winters in California to a different extent in different regions. But all of that put together, you know, we have a very strong El Niño event that is very far east in the basin, and we have some additional atmospheric factors that look like they're going to be in alignment with El Niño this year, as opposed to opposing it as they did in 1516. So, all of that stacks up to, you know, a winter outlook where there is, we could even say unprecedentedly high confidence.
I don't think that the level of confidence we've ever had in a California seasonal precipitation outlook is as high as we have this year. And that extends also to Northern California. The odds are always greatest in central and southern California during even the strongest El Niño events, but I think the tilt is so substantial that even Northern California, maybe even Southern Oregon this year, is significantly more likely to be wetter than average. And just to put this into a little bit of perspective, you know, digging around with the data, which is becoming a little bit easier than it used to be, as various entities make these data products open access immediately.
And by various entities, I'm mostly talking about the European Union Climate Services, which is where I'm getting a lot of this data this year. You know, this data is becoming available. It's a little easier to use coding tools to write up your own analysis really quickly. But the long story short is that there's technically still a slight chance that we could see a dry winter in California.
But what do I mean by slight chance here? I mean about five percent. So, there's a 95% chance, essentially, at this point, that we won't have a dry winter and that we'll have a wetter than average winter in California. And that is an extraordinary tilt in the odds for perspective. The odds of an even slightly dry winter in California are probably on the order of 5, 10%. The odds of a record wet winter, literally the wettest winter in over 100 years, are at least that large. So that maybe gives you a sense of the tilt in the odds, is if there's you know a 10 to 20% chance of a record wet winter and only a five to 10% chance of an even slightly dry winter. I know I'm throwing a lot of numbers around, but from a seasonal predictive perspective, which is just an extraordinary forecast for California.
Faith Kearns
It's really interesting to think too. I don't know how well any of the models predict things like rain versus snow. So obviously this is one of the big questions you're getting is just, you know, what where and sort of when and what form will the precipitation take, right? Like will it be rain, will it be snow, will it be more in the mountains, less in the mountains, etc. So, you know, just from an on-the-ground perspective, what are you what are you seeing in terms of thinking about snowpack and reservoirs and also drought over the long term?
Daniel Swain
Yeah, and this is where the slightly broader geographic picture gets interesting in the US West and the Southwest in particular, you know, California versus the Colorado, the rest of the Colorado basin. And yes, I've been getting that snow question a lot, both from water people and from people who like frozen precipitation and to go downhill fast on sliding on said frozen water. So obviously, there's a lot of interest from people who like to go skiing and from the ski industry about what this might look like. So often this these are the two big interest groups when it comes to mountain snowpack, the water folks and the ski folks.
And I think this winter is going to be have an interesting dynamic at play because in California, and certainly you know, central and southern Sierra, and probably Northern Sierra as well, also, you know, a good portion of the Great Basin and Southern Rockies have a pretty good shot at a wetter than average or maybe even a much wetter-than-average winter. And while most of California is not in a serious long-term drought, the broader Colorado basin to the, as you go inland, certainly has been long-term aridification plus short-term drought. There has been a huge problem, a growing crisis in the Colorado River. The strongest signal for a wet winter is in the lower Colorado basin. So, it's the part of the basin that is lower in elevation and doesn't contribute as much to runoff in the broader Colorado system. It is certainly better than indicating a dry winter in this region. Um any significant amount of water is going to be better than not having that water.
But the temperature question gets really interesting. And here is where the long-term climate trend, I think, becomes really important, because El Niño itself doesn't actually exert a super profound temperature signal throughout most of the West. It does usually make the California coastal region warmer than usual because it makes the water along the coast warmer than usual, and that does translate inland.
So, to a certain extent along the coast, a milder winter, not necessarily a warm one like last year, where there were lots of 70, 80, even 90 degree days in the middle of winter with a lot of sun, but sort of a higher floor, so not as much cool weather and just this rainy, mild conditions for much of the winter along the coast. I think in the mountains, you know, Sierra Nevada is coastally influenced enough because it's close enough to that Pacific Ocean, which right now is already much warmer than average and looks like it might actually be as much as 10 degrees Fahrenheit warmer than average this winter, which is an extraordinary number for a marine heat wave.
That probably means the snow lines are going to be creeping up the mountains. So, we might see well above average precipitation in a place like South Lake Tahoe, for example, which is at about 6,500 feet in elevation, but there's a good chance a lot of that precipitation is going to be falling as rain. And this is a good example of a place that has in recent decades seen a major shift from seeing mostly snow, if it was precipitating in the winter, to now seeing rain more often than not. It doesn't mean it doesn't snow in South Lake Tahoe, of course. It still does. They still get very heavy snowfall sometimes, but on average, they're typically on the wrong side of the rain snow line as that warming trend has caused that snow line to retreat further up the mountain.
And it's, you know, it's dark in a place like South Lake Tahoe because there's a ski resort where the chairlifts goes essentially right down to lake level, and so you can kind of traverse the elevational gradient, go back a couple of decades in terms of temperature by going up the mountain a couple thousand feet. This could well be a case this winter where the top of the mountain, you know, up at 8,000, 9,000 feet gets a tremendous amount of heavy, wet snow due to the increased precipitation and the just cold enough temperatures. But lower elevations, even you know, elevations that historically would have seen mostly snow, might this year see mostly rain.
And to the extent that this plays out across the intermountain west, it could be tricky because a lot of the west has some pretty high mountains. So, once you start getting into eastern Utah and Colorado, the upper basin, then it mostly is a question of high or low precipitation because even in a warm winter, it's usually still cold enough for snow in a lot of those upper elevation regions. So, if it's wet there, that's probably good news. But in the lower basin and in the Sierra Nevada, where the mountain where the average mountain height is a lot lower than it is in the central and southern Rockies, there's a good chance that we'll see high snow lines for most of this winter. And that has a couple of implications.
Obviously, you know, if you're a skier, it means that the high elevation ski resorts are going to probably fare better than the lower. If you care about water, you know, the good news in California is that I don't think we're going to see a dry winter. So, and we're not in a drought currently. Reservoirs, you know, in California at least are in pretty good shape. I don't really think they could be storing much more water than they are right now. I actually think we swing a little toward overabundance and questions of how does our water system, which is so finely tuned to storing water during scarcity and during droughts, how do we make sure that it remains safe during a period where there is more water than we know what to do with potentially, and where some of the water that we would have liked to have been stored in snowpack in this convenient time release storage that then melts later in the spring or summer is instead falling as rain and immediately becoming runoff during the storms that we see this winter.
And so, it means that, you know, the as an aside, you know, there's a lot of folks who worry about quote unquote rain on snow events, this idea that warm rain falls onto a deep snowpack and then melts it, thereby amplifying potential flood event. It can happen, but it turns out that I this was something that was surprising to me, by the way, when I really looked into this, into the literature and talked to some of the hydrologists who study this, that doesn't often happen.
It's very rare for a rain event to actually melt a significant snowpack and increase the amount of flooding. A lot of times a deep snowpack can actually absorb a lot of that, a lot of that rain, and it just becomes heavier, denser snow, but it doesn't really come out the bottom, which can actually be good for snowpack water storage and water supply. But the bigger issue is actually rain falling on places where it would normally have been snow where there was no snowpack to begin with, because essentially, it means your watershed suddenly got larger. It's the same rivers, the same streams draining, but the watershed is effectively larger because you have a greater area of places where you're getting runoff during the winter.
So, I know it's a question about snowpack, and I think it's going to be a very elevationally dependent winter. High elevations could do very, very well. We could see very high snowpack at 8, 9,000, 10,000 feet. And lower elevations could be very wet, but also too warm for significant snow accumulation. But where that fine line ends up is well, I would say it's above my pay grade, but honestly, I don't think there's anybody who can really give us that answer at this juncture.
Mallika Nocco
So, thank you for that, Daniel. Beyond the rain totals, you've also just flagged some hazards that don't always get as much attention. So, examples of these are king tides and the potential for major coastal flooding. What should water managers and communities be doing right now to get ready for this stuff?
Daniel Swain
Yeah, and we're having this conversation still in October, you know, and so this is a good time to be having it because there is still time to do some things to prepare for this, which is the main reason about, you know, that we as meteorologists, we as climate and water people talk about these kinds of things before they happen. It's not just to scare people for the sake of making headlines, it's so that we can do things to reduce risks and mitigate hazards and you know, reduce the amount of potential, you know, damage or other harm that occurs later this year. Um we could get lucky and we could have a wet winter, but everything is nicely spaced out and just you know distributed such that we don't get any big floods, but we get a lot of water, and maybe it gets a little bit on the cooler side and we get a great mountain snowpack. Wouldn't that be nice?
But I do think we have to be preparing for other outcomes, including increased flood risk, because frankly, the risk is a lot higher in a year like this one than in a typical year. And to be clear, it doesn't mean that we can't see large floods that we need to be prepared for in other years, and California's historical record is a great illustrator of the fact that it certainly does not take a big El Niño event to have very wet conditions or large floods. They can happen in any year, but the odds are higher this year. And so, there's really two, in California at least, there's really two hazards that are kind of or primary hazards plus some secondary ones that stand out.
One, as you mentioned, is the coastal flooding, which is mainly going to occur, it's already beginning to occur. There have already been some houses lost to the ocean in Long Beach, the Balboa Peninsula, for example, down in Southern California, was mostly inundated. A lot of people wrecked their cars and the bottom floor of apartment buildings and homes there had a lot of water damage. And that was a sunny day. You know that was this initial Kelvin wave coinciding with an ordinary high tide producing that level of inundation. As we go toward the November, December, and January King tides, we'll have another foot or two on top of the average high tides.
We can predict these in advance because they're essentially, they're astronomical, they're related to the sun and moon orbit around the Earth, highly predictable. So, we know exactly the dates that these high tides are going to occur. Because El Niño, as you're talking about the Kelvin wave and the thermal expansion, are probably going to add another one to two plus feet on top of that. And it's also the peak of winter storm season; we could see a significant winter storm coinciding with one of these three several day-long king tide periods.
The more of these risk factors we stack, the greater the risk that places not only along the oceanic coast, so facing the Pacific Ocean directly, but also connect coastally connected bodies of water. So, bays, estuaries, even some river systems, you know, and creeks that have some tidal influence, you know, in Northern California. I think folks who are outside of the area might forget it, but there's a tidal influence most of the way to Sacramento through the Carquinez Strait and into the San Francisco Bay Delta region, and then south and eastward toward Stockton. Stockton has a port that has a deep-water port for ships because it is tidal influenced and directly connected to the ocean.
So, all of these places, too, not just the immediate coast along the sandy beaches or the bluffs, but also these low-lying areas around San Francisco Bay, San Diego Bay, all the other bays and harbors in California, could potentially be, you know, at significant risk of inundation that could rival or even exceed anything we've seen historically. I mean, I've been speaking with several oceanographers, including, you know, from UC Santa Cruz, down at Scripps, UC San Diego, all of whom have indicated to me they think it's fairly likely that at least some parts of California will see record-breaking coastal flooding this year.
And if you think back to what that looked like in the past when there's been record-breaking flooding in previous years and decades, it has been very disruptive and, in some cases, quite damaging in places when it's occurred. So that's going to be something to keep an eye on. A lot of California's major infrastructure, transportation infrastructure along the coast or along the bays, low-lying areas, is potentially at risk, at least of being flooded and being unusable for a period, or potentially of being damaged. There are hundreds of thousands of Californians who live within a couple feet of sea level along a coastally connected body of water. And so that's something I know, you know, local communities, the state is already preparing for this.
You know, there's been some pretty urgent action to try and shore up the beaches, the sand berms, Southern California coast, Caltrans, the California Department of Transportation is essentially pre-positioning roadway barriers to try and make it so that people don't make bad decisions and drive into flooded areas. Um they're preparing to have vehicles and trucks and excavation equipment if there are mudslides and landslides and you need to open a road quickly. But you know, one thing I've been pointing out to some of these communities and some of these state agencies is that, you know, one of the challenges maybe we're not just going to have one episode of this. We're going to have multiple episodes, some of which could last several days at a time, in a semi-predictable way aligned with King Tide.
So, thinking about how do you message people, how do you communicate to people, these specific windows, you might not be able to drive on Highway 101. The Pacific Coast Highway might not be open. In fact, it probably won't be during these periods. So, what are the alternatives? Maybe you don't need to go there. Maybe if you do need to go there, you're going to have to know your alternate safe route. I can tell you that, as you know, as somebody who will be traveling on two different occasions in potential coastal flood zones during two of the three King Tide areas, boy, did I choose my travel windows correctly this year? I am planning to travel around the expectation that I will not be able to take the most efficient routes and that I might have to change my plans entirely to accommodate not driving through flooded areas.
So, you know, practical planning like that, especially since a lot of these coincide with the winter holidays this year, is important. For inland areas, you know, the freshwater flood risk is real from heavy precipitation. And, you know, this is something else. A lot of Californians, as you know, in fact, a vast majority, do not have flood insurance. There, I think that there's not as much awareness as there could be that your typical homeowners or renters’ policy doesn't typically cover flooding from a storm from fresh water. It might cover flooding if your sewer backs up or if your washing machine leaks or something, but it isn't going to cover if the creek rises. It isn't going to cover in many cases, in most cases, if the bay rises into your garage or the bottom floor of your home, for example. So that is still something that you can do now.
Flood insurance is a bit different than other kinds of insurance. It's an unusual case where you can buy it, you can buy it now. It goes into effect not more than 30 days from the date of finalizing a policy. And it's a rare occasion where you can buy insurance knowing your risk is going to be higher than average without the premium going up because of it. That isn't not usually how insurance works. That's a whole other conversation in the long run.
But in the short run, I think it is strongly advisable if you live in a flood zone a known flood zone or even in a place you think might could be in a flood zone or is close to a known flood zone, it's a great year to really seriously consider flood insurance. Um, but also basic things, you know, I'm having friends and family make sure that the culverts near their houses are clear, that that costs little or no money, helping your neighbors do that if they aren't inclined or able to do that themselves for whatever reason. Um, you know, talking to your neighbors about these sorts of potential relative interventions like clearing gutters, things that seem kind of trivial, you'll be glad you did these things.
You know, state of California is making sandbags available early so people don't have to go wait in line in the cold and the rain right before a storm. You can do it at your leisure on a 65-degree sunny day. Go fill up some sandbags if you think you need them, a couple of rolls of duct tape if you think you might just get a couple of inches of water. That's another great simple low-cost intervention. So, there's, you know, it's anything from a local government to a state government scale. The state is preparing, you know, the state has declared a preemptive state of emergency, you know, and having read through it. I think it's very grounded in the science and the predictions that we've got this year. It seems, you know, in my professional view, quite appropriate and well justified.
It doesn't mean there's a guarantee of disaster. It just means that, you know, some of the some of the stuff that I think can reasonably be characterized as red tape in terms of getting resources pre-positioned, making certain permitting processes more streamlined. You know, this year we might need to do some things quickly and pivot, and that you know enables local governments and state agencies to do those things faster. You know, some of these things are in place. You know, the good news is that there is there are there is preparedness activity going on, there is awareness, I think, that's spreading.
And, you know, peak impacts, I think, maybe this is the most important part, probably not arriving until later in November or maybe even December. So, whatever happens over the next month or two, it could be wet, it could be dry, and we'll get some rain. You know, we're having this conversation in late October. Looks like it'll be some finally some rain in Southern California later this week.
But the real big event is probably from late November, December onward, and perhaps through March, so we're going to have elevated sea levels and a greatly increased likelihood of very wet conditions through at least March. So, it's really that mid-December through March period where I think that would be the best period to have all your preps completed by that point.
Faith Kearns
Thank you so much, Daniel. I think this is probably a good place for us to kind of wrap up because I really have been finding this interesting thing where people are seemingly taking the Super El Niño news pretty seriously. And there's a lot of people who are kind of scared about it. And so, I think, you know, it's a really fine line to walk in terms of talking about this event and helping people prepare, but also not scaring them too much. And so, I appreciate that you're kind of offering this is the set of things and you know, here are steps that people can take.
I've been trying to do the same, just you know, sort of telling people if you're inland or whatever, high winds, you know, your gutters, et cetera. Like, you know, I don't want to scare people unnecessarily, but there are very pragmatic steps you can take. And I think it's super important for people to also know that their town, city, regional governments are actually taking these things seriously, also already. So that's a positive thing.
We always like to kind of end on a note of asking our guests if there's anything else that you would like to add and anything that people can do to support the work that you do, which I know is quite prolific and almost all entirely publicly available. So, if there is anything we can do to support you, let our listeners know.
Daniel Swain
Well, thanks, Faith. I mean, I think I would close really by reiterating what you were just emphasizing yourself, which is that, you know, there is a bit of a dueling reality here. We do genuinely have an El Niño event that that is quite extreme. Um, and we may see impacts that rival or perhaps even exceed some of the impacts we've seen in California and elsewhere in the world from other previous very strong El Niño events. And there's a little bit of a global warming twist in there is that it kind of ups the ante a little beyond. And so that, you know, understandably, I think that does sound a little bit scary.
My own perspective as a climate scientist and a meteorologist is a level of genuine concern because we really haven't seen this before. But on the other hand, you know, we this is not some completely new phenomenon. This is not something that is totally misunderstood. This is something that we actually do understand quite well. In fact, our prediction to date, you know, from the spring has been really good. So, I think we do have a general sense, you know, of where we're headed.
It's not a complete mystery. It's you know, we can't be exactly 100% sure of the outcome, but we have a reasonable, bounded expectation about what could happen. And that is why, you know, those of us in this field have really been urging all these preparedness and preparatory actions, is precisely because we can't mitigate some of those risks if we have that advanced warning, and we do in this case. Isn't that amazing in a sense that we were able to sort of see some of this coming, not just a week or two in advance, not even just a month or two in advance, but in some cases, this will turn out to have been a prediction from the spring about an event that we'd never seen before happening that comes to pass roughly when we thought it would. So, I think there's some there's some good news in there about our ability to understand the way the world works and improve outcomes because we're able to anticipate when things might get a little bit dicey.
And I think, yes, I mean, I think in general, you know, we've all experienced winter storms before. We've all we all know that it can rain, it can get windy, and there are shades of you know, degrees of severity of all these things, and we might see sample more from the more severe side of the spectrum this winter, but they aren't. You know, it it's a familiar pattern, just a little more extreme, and there's a lot we can do in the meantime to, you know, to make sure that we're prepared, that our neighbors are prepared, that our communities are prepared.
And, you know, side note that a lot of those things we've been talking about in terms of preparedness, they're useful things to be doing anyway. They're things that ideally, we'd all be doing to begin with, but it's a good reminder that we should be doing them and that there might be extra benefit this year specifically to making sure everything's up to date, that we know how we want to manage these things. So that that would be my closing thought today.
Faith Kearns
Well, thank you so much, Daniel. It's been great having you on Water Talk again, and we really hope that this episode helps folks start to or finish up preparing for what could be a pretty large set of storms. So, thank you so much, Daniel.
Well, that was a fascinating conversation with Daniel Swain about El Niño, and we always like to leave folks with some of the things that we took away from the interview. And I think for me, one of the most interesting things about El Niño as somebody who works on kind of multiple other disasters, including wildfires and floods more generally, drought. Um, one of the interesting things about El Niño is we actually do have time to prepare. So, it's sort of this, you know, you can have a warning that's sort of a little bit more uncertain because forecasts in general can get kind of challenging the further you are out from the event, right? And so, in this case, we have kind of a long runway.
We have had and continue, even right now in October, to have kind of a long runway to prepare. And so, what I really appreciated was talking with Daniel a little bit about the things that people can do to prepare, because I do think there is a sort of potentially overwhelming sense of fear that people have. And on the other hand, sort of a sense of not worrying about it at all because it's in the news, but it's not happening, right?
And so, I think just this middle ground of being able to have the time to prepare and do some of the things that we always have to do around the places we live anyway. You know, cut, make sure your trees aren't going to fall on your house in high winds and clean out your gutters. And, you know, you know, if you live on a creek, you know, make sure that you're talking to your city officials about what happens if a culvert gets clogged with downed logs or whatever. So, I do think it's a really interesting event to have time to prepare for.