University of Miami Researcher Weighs in on Key 2024 Hurricanes Season Trends

A Conversation With Brian McNoldy

As the 2024 Atlantic hurricane season approaches, the climate signals are anything but typical. The transition from El Niño to La Niña and unprecedented sea surface temperatures in the Atlantic have meteorologists and communities paying close attention to the potential severity and frequency of this year’s hurricane potential.

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Brian McNoldy:

We don’t have any historical examples to look at of what happens when the ocean is this warm and during a La Niña, we don’t know. We’ve never had a La Niña combined with ocean temperatures in the tropical Atlantic, as warm as they are. So we don’t know.

Maiclaire Bolton Smith:

Welcome back to Core Conversations: A CoreLogic Podcast where we tour the property market to investigate how economics, climate change, governmental policies, and technology affect everyday life. I am your host Maiclaire Bolton Smith, and I’m just as curious as you are about everything that happens in our industry.

Hurricane season officially starts every year on June 1st, and while weather doesn’t always follow a calendar, it does follow patterns. From sea surface temperatures to the shift from El Niño back towards La Niña, there’s plenty to pay attention to as the 2024 Atlantic hurricane season begins. However, even though there are indications that this may be a very active season, the future remains far from certain. So to talk about what these meteorological trends mean for this hurricane season, what we should pay attention to and what we can possibly expect, we have Brian McNulty, a senior research associate at the University of Miami’s Rosenstiel School of Marine, Atmospheric, and Earth Science. Brian, welcome to Core Conversations.

BS:

Maiclaire, thank you. I appreciate the invitation to be here. Thank you very much.

Erika Stanley:

Before we get too far into this episode, I wanted to remind our listeners that we want to help you keep pace with the property market. To make it easy, we curate the latest insight and analysis for you on our social media where you can find us using the handle @CoreLogic on Facebook and LinkedIn or @CoreLogicInc on X, formerly known as Twitter and Instagram. But now let’s get back to Maiclaire and Brian.

MBS:

I guess you’ve seen a couple of hurricane seasons since and now very experienced in this field. So based on what you know and what you’ve seen and the research that you’ve done, what do you think we might expect for this year?

BS:

This is really quite a year to be in the field and not in a great way, I guess. And I say that because we fully expect El Niño, which we’ve been in for almost a year now, to transition to La Niña by the heart of hurricane season.

And just to zoom out on what that means, generally El Niño’s reduce Atlantic hurricane activity and La Niña’s enhance Atlantic hurricane activity. So we’ve got that shift happening, but on top of that, we’ve got ocean temperatures in the tropical Atlantic that are warmer than we’ve ever seen them be for this time of year. So I guess where I would rank this year then is we don’t have any historical examples to look at, what happens when the ocean is this warm. And during a La Niña, we don’t know. We’ve never had a La Niña combined with ocean temperatures in the tropical Atlantic, as warm as they are, so we don’t know.

MBS:

Wow, okay. There’s a lot of unknown, and we do talk a lot on this podcast or we have talked a lot on this podcast of the importance of sea surface temperatures, ocean temperatures, and how they’re important for hurricane generation. When you say we’re seeing something we haven’t seen before, what degree do you mean? Is it a degree more than ever, or is it significant?

BS:

It’s significant, and it depends on what region you’re looking at. If it’s the Caribbean, the Tropical East Atlantic, the Gulf of Mexico, all of those regions are warmer than they’ve ever been for this date. So the exact number depends on what region you’re looking at, but the Caribbean is actually really striking right now. If you average the sea surface temperatures over the whole Caribbean, it’s higher now than it would be at its normal peak. So in mid-September to late September is when it normally reaches its warmest. It’s already warmer than that.

MBS:

Wow. How many degrees does the temperature usually go up throughout the season? Are we looking that now? So it is expected that it’s not going to get there and stay, it’s going to continue to increase. Are we looking at, it may go up five degrees, 10 degrees? What is an on average, and again, this sounds like it’s probably different depending on the region of where you are, but how much more can we expect the temperatures to increase?

BS:

So again, if we just pick on the Caribbean since I was talking about that, that generally hits its coolest in March or so, late February into early March. And then as I mentioned, it reaches its peak into late September-ish. And the range we’re talking about there is about two and a half to three degrees C, so about five to six degrees Fahrenheit is what the Caribbean changes by.

MBS:

The fluctuation is?

BS:

Yeah.

MBS:

So it’s not extreme, but it’s still an oscillation that it goes from cooler to warmer?

BS:

Yeah. Yeah, and I guess that’s a point of reference in general when we’re talking about ocean temperatures is small differences really do matter.

MBS:

Okay, that’s important.

BS:

The numbers don’t always sound big, but when you’re talking about an area average of an ocean, it’s a big deal.

MBS:

Sure. Now, what do we think it’s going to mean for hurricane season this year? So if we are above average temperatures at this time of the year now, it’s going to increase. Is that just going to mean that it’s ripe generation for hurricanes?

BS:

Yes, that’s the very brief answer to that. Yes. Hurricanes need a handful of ingredients to come together. So even though the tropical Atlantic right now is absolutely ripe for hurricanes, the rest of the components, they’re not there yet. But as soon as the atmosphere is ready to play, the ocean is more than ready to play.

ES:

Ocean temperatures in the Atlantic have already been consistently higher than the record warm temperatures set in 2023. Interested to learn more about how sea surface temperatures may affect the 2024 hurricane season? Click the link in the show notes.

MBS:

Now, I remember last year we heard the same thing, that the temperatures were warmer than they’d ever been before, and last year’s hurricane season didn’t really amount to very much of anything. And you’ve already alluded to the fact that we were in an El Niño and we’re heading towards a La Niña now, and that maybe had something to do with it too, but ocean temperatures are not the full picture, but we were kind of anticipating a more active season last year than we probably got. What happened last year? What do you think happened last year and what might be different about this year?

BS:

Yeah, that’s a great question. So 2023, when we were heading into that hurricane season, there was the great unknown of which of the major influences would win out. We had very warm ocean temperatures in the Atlantic versus El Niño, and those two have opposite tugs on hurricane activity. As it turns out, 2023 hurricane season was above average. We had in terms of there’s this quantity called ACE, the accumulated cyclone energy that was about 20% above a normal hurricane season. We had three major hurricanes, two category fours and a category five last year. And so all of that was in the midst of an El Niño, so for sure the warm Atlantic Ocean temperatures won.

MBS:

I think what we saw last year, it was a very active season. There were a lot of events. Those events were significant tropical cyclones, but there wasn’t necessarily landfalling hurricanes, which is why maybe it seems like it wasn’t that a big hurricane season year last year, but it actually indeed was.

BS:

Yeah, that’s exactly it. Last year was very odd in terms of tracks. So with all that action that we had, there was only one hurricane landfall anywhere in the Atlantic all of last year, and that was Hurricane Idalia in Florida, but that’s it. That was the only landfall anywhere in the Atlantic.

MBS:

That’s crazy.

BS:

Everything else stayed way far east and turned north out over the ocean.

MBS:

And I guess that really does tell you too, that we hear these forecasts come from the National Hurricane Center, and then there’s a number of other outlets as well that do their forecast on hurricane season. And just because they’re saying it’s an above average year, that doesn’t mean we’re going to get a major loss that year, but it does mean there’s a higher probability of getting a major loss that year because the more events we have, the higher probability that one may make landfall and making landfall in a populated center as well too, I guess.

BS:

Bingo. Yeah. And last year with the amount of activity there was, and a major hurricane landfall in the US still ended up relatively nice, I guess, for an insurance viewpoint in that even hurricane Idalia that did make landfall in Florida managed to find a very sparsely populated part of Florida to hit.

MBS:

Well, it is really interesting, and part of me does worry when we have active seasons like that that don’t have a major impact because I think it gives a bit of a false sense of reality, especially to the public and potentially to insurers as well too, who are insuring these events that they feel like, “Oh, well, this was a very active season and it didn’t amount to anything from a loss perspective, so maybe we don’t need to worry about it.” And that just seems like a recipe to disaster in many ways.

BS:

Yeah, I think that’s pretty much it. You could have easily had 2023 end up in a very different way, even if that single landfalling Hurricane Idalia, if that had hit a major natural area, it would’ve been an extremely expensive year.

MBS:

It really could have been.

BS:

Just with that one change.

ES:

It’s that time again, grab a cup of coffee or your favorite beverage. We’re going to do the numbers in the housing market. Here’s what you need to know. In March, US single family rents held relatively steady at 3.4% on an annual basis. However, attached rental prices declined by 0.6% year over year. That is the largest drop recorded in 14 years. For homeowners, prices were not as steady. Thanks to skyrocketing home prices in 2021 and 2022, a growing number of homeowners are finding they may owe taxes if they sell their properties. Almost 8% of US homes sold in 2023 exceeded the capital gains tax limit of $500,000.

Another surprise for some homeowners were property taxes in 2023. For homeowners in the 33109 zip code of Miami Beach, Florida, median annual property taxes exceeded $50,000. The second-highest median property tax payment was in the 94027 zip code for Atherton California. Median property taxes in 2023 were just above $46,000. Although Texas is not always associated with a high cost of living, the Dallas area communities of University Park and Highland Park ranked number five and number 10 respectively for highest property taxes in the nation. And that’s the SIP. See you next time.

MBS:

The other thing that comes to mind is there’s a lot of talk when people talk about climate change, about sea level rise, and can we talk a little bit about what does this mean from a hurricane perspective? I know obviously related to storm surge probably, but can you just talk about sea level rise and how that may be an increasing risk that we need to think about?

BS:

Yeah. It’s kind of a threat that gets overlooked because on the scale of storm surge, it’s relatively minor. Let’s say in southeast Florida here where I’m at, we’ve had probably about seven to eight inches of sea level rise in the past 30 years. And that might sound like a small number to people that don’t live here. It’s a very observable change to people who do live here.

MBS:

Especially if you have a coastal property, I’m sure.

BS:

Yeah, because it’s a flat, low-lying place, so that makes a difference. And so when we look at that in terms of hurricanes and what a storm surge can do, and I’m just going to make up a number. Let’s say there’s a hurricane here that produces a four-foot surge, and now we just use that eight inches that I just used as an example in the past 30 years. So that exact same hurricane now compared to 30 years ago, will flood more places than it would have without sea level rise. And you can go from ocean water just coming up to your property and causing basically no damage to having eight inches of ocean water in your property and causing a lot of damage.

MBS:

Significant damage. Wow.

BS:

You can go from none to a lot in those eight inches.

MBS:

Wow, okay. No, that is significant. So I think something that definitely to keep an eye on because sea level rise is not going away. It’s something that is projected to continue as well. So definitely could continue to be more of a threat as we continue within years to come as well.

BS:

Yeah. It just makes a bad problem worse.

MBS:

Sure. Well, I think when we’re talking about hurricanes having a bad problem get worse is not necessarily a good thing.

BS:

Exactly.

MBS:

I guess the other thing too, that comes to mind, anybody that pays attention to hurricanes, whether you live in a hurricane-prone area or not, are very familiar when the National Hurricane Center puts out their forecast, they have this cone of uncertainty. And over the years, I think there’s been a lot of refinements on that cone of uncertainty, but there’s a lot of just that, uncertainty, and what the actual path of the event will be when the track of the hurricane is traveling. So can you talk a little bit about what exactly is the cone of uncertainty? Why did they start doing it and how can it improve and what are some of the things that you know about that?

BS:

Yeah, so there’s a lot to unpack in that, but I’ll start with just explaining what the cone is. It was introduced in 2002 basically as a way to show uncertainty around a track format because they’re not perfect. The errors in a forecast do increase with time. And so what the cone of uncertainty is it’s a way to show the National Hurricane Center’s own track error over the past five years. So they only use their own track errors in a certain way, but only using the past five years. So it kind of updates itself slowly because each year you’re only including a new year and throwing the oldest year out, and it notches its way up that way. And in general, the cone shrinks each year because track forecasts generally improve. So when you’re throwing out an old year and including a new year and five year bins shift.

MBS:

A bit more refined each year?

BS:

Generally, but there is a bit of a… In 2024 now, the newest cone is actually increased in size compared to recent years. For a two-day lead time, it’s the largest it’s been since 2018. And for a five-day lead time, which is at the end of the cone, that’s the largest it’s been since 2016. Not by huge numbers, but it’s not shrinking.

MBS:

Right. So that’s interesting. I want to unpack that a little bit because I think generally people would like there to be, “This is the path with zero uncertainty”, but that is fairly impossible to do because understanding what mother nature is going to do is not always intuitive. And even though we may suspect how a hurricane is going to travel for various reasons, it may change path. And I think having uncertainty is always important. So I think a lot of people may intuitively think, “Well, why is it getting bigger?” But me personally, I think, “Well, I think I want that uncertainty there so that I can capture the bounds of what might happen here.”

BS:

Yeah. And it brings up a really important part of forecasting nature in general. The forecast error will never be zero. In fact, it’s impossible to have zero forecast error. So there is this thing called the limit of predictability, and there’s hints. One can make a case maybe that we’re approaching that, especially for the days one, two, and three forecasts. When you go out a little further, I think there’s still room for improvement, but the days one, two, and three track forecasts over the past ten-ish years, the cone size is more or less flatlining.

MBS:

Oh, wow. Okay. Interesting.

BS:

Yeah, it’s an interesting property that might suggest that at least at those nearer lead times, we’re nearing that limit.

MBS:

This then relates to modeling of hurricane tracks and where it’s going to go. And can you talk a little bit about that too? Because I know that generally when we’re looking at what the hurricane can do, there’s various models and you can look at these are the different options and based on different things like this is potentially how this event may go. And sometimes these models are very different or have very different outputs. So can you talk a little bit about why these models are important, how they differ, and how they can be used or interpreted in ways too?

BS:

Yeah. I mean, it’s getting increasingly hard to make improvements. As I was saying, for both track and intensity, I think there’s more room for improvement in intensity. Getting improvements in track, it’s getting harder and harder to squeeze moisture out of that sponge, but we try. So yeah, there’s a lot of effort going into the hurricane models. There’s actually in 2023, new hurricane models were put into operation and we’re going to retire a couple previous hurricane models.

So yeah, there’s a lot of work going into maintain and potentially squeeze out more improvements as much as we possibly can. And it’s important to have accurate models. That’s the reason so much money and effort gets put into this. There’s obviously a lot at stake. There’s property at stake, there’s lives at stake. If you can accurately evacuate people who need to evacuate and don’t evacuate people who don’t need to, that’s extremely important.

MBS:

Yeah. Yeah. Well, I mean, the famous saying is all models are wrong. Some of them are useful. And I think that’s the key, right? Is focusing on how can you make these models useful depending on what your purpose may be, whether it’s public safety from an evacuation perspective, if it’s from more of a scientific perspective or from an insurance perspective of understanding what the potential loss might be.

BS:

Yeah. And as you said, the models have very distinct answers sometimes what they show in their forecast. And I think it’s kind of important for the average person to not play too much in that realm of looking at the models because they really have their nuances and their biases, and it’s important to just let the experts at the Hurricane Center boil all that down. They assimilate all that. They are very, very well acquainted with all the different models and their quirks, and then that’s how they come up with their forecast. And that’s the one that we need to put our faith in because the models can do windshield wiper-y things, and that’s not what you want.

MBS:

Right, Right. And it is the boiled down view with the bands of uncertainty within the cone of uncertainty, that really is the focus.

BS:

Yeah.

MBS:

Wow. Well, so much to be said on what this year is going to look like. Brian, I think we are ripe for generation, as we have said, so it really is going to be interesting to see.

ES:

Before we end this episode, let’s take a break and talk about what’s happening in the world of natural disasters. CoreLogic’s Hazard HQ Command Central reports on natural catastrophes and extreme weather events across the world. A link to their coverage is in the show notes.

Looking at the 2024 hurricane season, CoreLogic released its annual hurricane risk report. In the report, we identified that over 32.7 million residential properties with a total reconstruction value of $10.8 trillion are at moderate or greater risk of hurricane wind damage. Additionally, approximately 7.7 million properties with a reconstruction cost value of $2.3 trillion are at risk of storm surge flooding. To read the full report, find a link in the show notes.

MBS:

If our listeners are interested in some of the research that you’re doing, how can they learn more about what you’re doing and some of the research that you’ve got?

BS:

Oh, yeah. I definitely try to keep a pretty active presence on social media. I generally use Twitter slash x and BlueSky. I’ve been doing that for I guess nine or 10 months now, and I am @BMcNulty on those two platforms. And I also have a blog that I started in 1996, actually before the term blog was even invented. So that’s still going. This is, I guess, I don’t know, what is this year 29 now or something like that. And that’s BMcNulty.blogspot.com.

MBS:

Fantastic. Well, Brian, thank you so much for joining us today on Core Conversations, a CoreLogic podcast.

BS:

My pleasure. Absolutely. Thank you.

MBS:

All right, well, everyone will be watching the season as we go through hurricane season, and I know that we will be back with tidbits throughout the season as well too as things happen. So thank you for listening. I hope you’ve enjoyed our latest episode. Please remember to leave us a review and let us know your thoughts and subscribe wherever you get your podcast to be notified when new episodes are released.

And thanks to the team for helping bring this podcast to life producer, Jessi Devenyns, editor, and sound engineer, Romie Aromin, our facts guru Erika Stanley and social media duo, Sarah Buck and Makaila Brooks. Tune in next time for another Core Conversation.

ES:

You still there? Well, thanks for sticking around. Are you curious to know a little bit more about our guest today? Brian McNoldy is a senior research associate at the University of Miami’s, Rosenstiel School of Marine, Atmospheric, and Earth Science. He works on three different teams, and his research covers a broad spectrum of hurricane related topics, including hazard communication, forecast valuation, and high resolution modeling. He is also a senior research fellow at the University of Miami’s Client Resilience Academy. Prior to Miami, he was involved with hurricane research at Colorado State University’s Department of Atmospheric Science for over a decade. In 2022, the Miami New Times selected him as best meteorologist in its annual Best of Miami rankings, citing him as Miami’s de facto hurricane expert.

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