A look back at the 2020 Hurricane Season – An Interview with Hurricane Researcher and Forecaster Dr. Phil Klotzbach
What we’re talking about
The 2020 hurricane season ends November 30th. This hurricane season resulted in historic impacts across the U.S. including a record five landfalling storms hitting Louisiana. The effects from this season were felt in almost every state along the Gulf Coast and up the Eastern Seaboard of the U.S. In fact, every coastal county or parish east of the Mississippi — except one — was under a tropical-related watch or warning at some point during the season. To put this historic season in perspective we welcome back Dr. Phil Klotzbach — one of the world’s leading researchers in tropical meteorology and heads up the research division at Colorado State University.
Key Takeaways
- One of the major takeaways from the 2020 Hurricane Season was the number of storms that underwent rapid intensification right at landfall. Another impact from this record season was the unusual activity in the last third of the season in October and November.
- Louisiana was the hardest hit state with an historic five landfalling storms. This season’s atmospheric conditions produced a favorable environment for storms, especially in the Gulf of Mexico.
- As Dr. Klotzbach looks ahead to 2021 he predicts no significant El Nino or other major change in the atmosphere to indicate a dramatic change in next year’s season. Although, he doubts we will see the 2020 record number of storms repeated.
Supplemental Links:
- Colorado State’s November 30th 2020 Season Verification Report.
- Learn more about Colorado State’s Tropical Meteorology Project.
The 2020 hurricane season ends as one of the most noted in history with the most active named storms in a season, the most landfalls in the continental U.S. in a season, the most activity recorded so late in the season, the list goes on. Just how significant was 2020? Colorado State Tropical Meteorology Researcher Dr. Phil Glotzbach joins us to take a look back at this year and a look ahead to what might be in store for 2021. Storm after storm this year were these kind of rapidly intensifying storms or at least intensifying storms right up to the point of landfall which obviously is a huge challenge from a warning perspective as well as a preparation perspective and a mitigation perspective.
As storms are intensifying right up to the point of landfall that poses extremely problematic in that regard. This is the Disaster Recovery Roundtable, a platform to explore, engage, and educate the emergency management community. Our topics are timely and relevant, intended to promote the exchange of ideas and best practices.
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Now, here’s your host, Greg Paget. And thank you Steve Henderson. Thankfully the 2020 hurricane season officially ends today after historic impacts in the United States.
Louisiana alone saw five landfalling storms and impacts from this season were felt in almost every state along the coast and all the way up the eastern seaboard. In fact, every coastal county or parish in the U.S. east of the Mississippi except one was under a tropical related watch or warning at some point during this historic season. To put the season in perspective, we welcome back Dr. Phil Glotzbach, one of the world’s leading researchers in tropical meteorology and who also heads up the research division at Colorado State University.
Phil, welcome back to Disaster Recovery Roundtable. Hey, thanks so much for having me, Greg. Phil, we had you back in the early part of the season, first week of June, as part of our special coverage of the 2020 season and you told us back then it was going to be a busy year.
I don’t think any of us predicted it was going to be as crazy a hazard that it was with so many storms. Have you even yourself been surprised at what 2020 has produced? Yeah, I mean 2020 has been a really, really interesting year. Obviously, we broke the number of storms forming in a season record, so the prior record was 28.
Had we done this interview at the end of September, however, I would have said, okay, at the end of September, we had 23 storms, but we’d only had two major hurricanes. So, you know, from an intensity perspective, it was kind of, you know, the storms have been there. We obviously had Hurricane Laura, which was very damaging and devastating to southwest Louisiana, but all in all, those integrated metrics that we look at like accumulated cyclone energy, just a little bit above normal.
However, October, November, we had seven storms and we had four major hurricanes. We had Delta, we had Epsilon, we had Eta, and we had Iota, and we just missed out on the fifth major hurricane was Eta. So, we had four major hurricanes out of seven storms.
So, the last few storms of the year were very intense, and so when you look at those integrated metrics like accumulated cyclone energy, those metrics shot up to very high levels now. So, now pretty much any number that you look at, the season was very active, and especially active, obviously, for the United States. We were hit by 12 different storms, and six of those were hurricane strength.
So, obviously, a very, very active season from a landfall perspective, especially for the state of Louisiana. And you talk about seven storms in that October, November period. That’s the same number of storms we had in 1992 for the whole season.
Is that a pretty big number to have such so late in the season? It is, and especially the number of major hurricanes. And one of the things I was looking back at today was, you know, you look back, we had three major hurricanes form after October 20th this year. The most we had ever seen in any prior season was one.
So, we just had a tremendous number of these late season storms that are very, very strong, and obviously, you know, like seemingly they were getting progressively stronger and stronger. We had Eta, which maxed out as a Category 4 hurricane. Then we had Iota, which actually even reached Category 5 hurricane strength.
Now, I know you’ll be doing a lot of research, I’m sure, in the off months as we get between this season and the next one starting, if there will even be a break between the two, who knows. But what is going to be some of the things you’re going to look at as far as the contributing factors that made this season just so unique and set all these records? So, for CSU, we do a seasonal hurricane forecast verification, which actually comes out today, November 30th. So, we’ll talk about how well the seasonal forecast verified, and then we’ll look it through kind of some of the large-scale factors that went into it.
But obviously, that’s a fairly short, or the document isn’t short, but, you know, that doesn’t allow much time for research because we’ve obviously been very busy with the season. So, there’s some data in there, but then we’re actually planning on doing one, if not two, kind of more peer-reviewed journal article-type papers, hopefully one specifically on the late season, the October-November period, and then probably another one looking at the full hurricane season, potentially looking at some aspects of kind of what made the season behave the way that it did, because we had a tremendous number of storms. We had six major hurricanes, which is just one below the record of seven major hurricanes.
But we didn’t have a lot of these long-track cyclones all the way from Africa. If you had asked me in June, and maybe we even talked about it in June, I probably would have said, yeah, we expect to see these storms tracking all the way across from Africa. We had a lot of storms form off Africa, but in general, those storms didn’t make it all the way across the basin.
The only kind of long-track storm that we had was Hurricane Teddy, which most people don’t remember because Teddy, thankfully, was mostly just a fish storm, mostly impacted water. It did make landfall as a post-tropical cyclone in Nova Scotia, but thankfully, the damage wasn’t too significant. A lot of the storms that were higher impact storms in 2020 formed much closer to land either in the Caribbean, in the Gulf of Mexico, or just off the southeast U.S. coast.
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Yeah, one of those other factors, though, is we saw so many storms rapidly intensify as they were coming on shore, making landfall. Was that another unique characteristic of the season? Yeah, and to me, that’s kind of what’s going to stand out in addition to, obviously, just the absolutely crazy number of storms that we got in 2020, was just how many of these storms are rapidly intensifying up to the point of landfall. Obviously, rapidly intensifying storms, that’s nothing necessarily new.
We’ve seen that in the past, but this year, oftentimes, storms rapidly intensify, but as they approach land, they tend to weaken. They start to interact with the landmass even before they make landfall. Usually, the water temperatures near the coast, especially in the Gulf of Mexico, tend to be somewhat cooler, especially in the Northern Gulf, so that tends to kind of weaken them.
They tend to get more dry air coming off of the land. It helps to kind of bundle up the thunderstorms, kind of mess those up, because storms tend to degenerate before they make landfall, but this year, obviously, again, for us in the U.S., Hurricane Laura was the most kind of the most classic example of a storm that basically was intensifying pretty much right up to the point of landfall. Also, Hurricane Zeta was also intensifying pretty much right up to the point of landfall as well.
Sadly, it didn’t quite meet that rapid intensification criteria up to the point of landfall, but it also was intensifying pretty much right up to the time that the eye crossed the coast, and so that’s one of the reasons why, if you look at the number of storms and then look at, say, the accumulated cyclone energy, you would have expected more ACE given the number of storms that we have, but that’s because these storms were still just ramping up right up to the point of landfall. Often, what kills storms is they run into cold water or they get sheared apart, whereas this year, what put the brakes on most of these storms was they just smacked into land, and even these last two significant major hurricanes in the Caribbean, both Eta and Iota, while they did weaken slightly right before landfall, they were pretty much ramping up to, say, about 12, 18 hours before they made landfall, so storm after storm this year were these kind of rapidly intensifying storms or at least intensifying storms right up to the point of landfall, which obviously is a huge challenge from a warning perspective as well as a preparation perspective and a mitigation perspective as storms are intensifying right up to the point of landfall, that poses extremely problematic in that regard. In referencing those two Caribbean monster storms that we had, both of them hit so close, you know, what, 12 miles or 15 miles from each other from the point of landfall.
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How historic is that for Central America? I mean, yeah, I mean, it’s really, I mean, it’s very historic for them. If you look at Nicaragua, the frequency of getting hit by any significant major hurricanes is fairly low. I mean, we had one Category 3 hurricane hit Nicaragua in November before, that was the strongest one, and we had two Category 4 hurricanes hit Nicaragua 13 days apart in 2020, so it was extremely significant for them, also very significant for Honduras, especially from a rainfall perspective, tremendous amounts of flooding, you know, still with the death toll coming on from Iota, you know, that death toll is likely to still continue to increase as we kind of get more information from that region.
Unfortunately, it just takes time to kind of get that information out, but yeah, I mean, it’s going to be just a humanitarian, real humanitarian challenge down there, because I know having supported some of these groups, like World Vision and things like that, and you get their emails, and they say like some of their distribution centers and stuff were damaged or destroyed by Iota, and then so Iota comes along, and they can’t even help as much because their distribution centers aren’t there anymore, so it’s going to be, you know, a long haul for Nicaragua, Honduras, and other parts of Central America after these two hurricanes. I also think it’s kind of unusual or maybe just crazy that we had all these storms. Florida really got spared, if you look at really what happened to Louisiana and the rest of the Gulf, and with so many storms, you know, 30 plus, whatever, you would have thought that there would have been a few more impacts, at least, across the Florida peninsula.
I mean, until you had Iota late, you know, really late in the season, Florida hadn’t been, no hurricanes have been, you know, named storms that made landfall in Florida. Obviously, Sally, even though it made landfall officially in Alabama, did do quite a bit of damage in the panhandle, so the panhandle of Florida have been significantly impacted, but in terms of actual landfall of a storm crossing the coast, they hadn’t had any until Iota, which Iota made two landfalls in Florida, one down along the Keys and then recurved up and made landfall north of Tampa, but even from, even Iota wasn’t a particularly highly impactful event, not nearly as impactful as the storms, obviously. From a 2020 perspective, Louisiana was really ground zero for these, the storms this year.
Stay with us. We’ll have more from Dr. Glotzbach when we return, including how his two-week short-term forecast product is helping emergency managers keep a closer eye on the season as it progresses through the year. We’ll be right back.
You’re listening to Disaster Recovery Roundtable. Now, here’s a preview of our next episode. Giving Tuesday, 2020 is December 1st, and for those of us who work in emergency management, there are so many great non-profits to support, especially this year.
We’ll hear how the United Way’s Emergency Response Program has adjusted to support this year of disasters. Our guest is United Way’s Tamika Fales. Most United Ways are so embedded in their communities, and they have very good working knowledge of not only what they are doing, but what all of their local partners are doing.
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You’re listening to our special coverage of Hurricane Season 2020. Now, back to your host, Greg Paget. And welcome back.
This is the official end of the 2020 hurricane season, and our guest today is Dr. Phil Glotzbach with Colorado State University. Phil, I know you and your team were very busy this year trying to keep up with 30 named storms, and I guess it was helpful that you did have your product where you look at the season on a two-week interval compared to just the season as a whole, which helps to really look at trends that might be developing as the season progresses. You can have active periods in an inactive season, or alternatively, you can have quiet periods during an active season.
And so, for example, in 2020, we had a period of about from September 22nd to October 2nd, we had no storms. That’s typically a very active part of the Atlantic season. And so, you know, we kind of saw it coming and talked about it, but it’s one of those things that, you know, when you’re forecasting active season, you get a really quiet period during what should be a climatological peak.
It’s surprising, but also, maybe the forecast isn’t going to verify, and then things really ramp up. And so, we put out two-week forecasts, one forecast every two weeks. And so, the forecast this year verified pretty well.
It was actually pretty challenging, though, because the way that they timed, the way that these forecasts timed, we put out a forecast, I believe, on September 30th. And so, we had had nothing for about eight or nine days, and the models were kind of all over the place with whether we’re going to get more storms. And so, I look at what the models are forecasting, but then also look at kind of what the large scale environment looks like.
And it looked like the environment was favorable, but the models weren’t in great agreement as to what was going to happen. But I said, well, the environment looks favorable, then something should happen. And then 24 to 48 hours, it was like, oh, and then the models all jumped on.
It was like, then it looked like it was an easy forecast. But the day I put it out, it was a really hard forecast. I agonized over that one.
And so, I think, first of all, I enjoy putting them out, because I think it’s hard. It’s really hard doing these two-week forecasts when you don’t have storms actually out in the ocean, trying to figure out what’s going to form. Models don’t do a great job predicting storm genesis.
Sometimes it’s some storms, all the models get like iota. I mean, every model was like, this thing’s going to go and it’s going to be big. But other storms like Delta, most of the models didn’t have it.
It was a category four hurricane, but most of the models three or four days out had nothing. So, not every monster hurricane or even every hurricane is well forecast. The models go over the place.
So, you try to use a large-scale environment and what the large-scale environment looks like it’s going to be. So, one of the factors that we look at is what’s known as the Madden-Julian Oscillation. And the Madden-Julian Oscillation is basically tropical thunderstorm activity that propagates around the globe about every 30 to 70 days.
And as that does so, it alters basically where your thunderstorms form and then also alters what your wind patterns are going to be like. So, whether you’re going to have more or less of that vertical wind shear, which is the change in wind direction with height in the atmosphere. Too much shear is good for us, bad for the hurricanes.
And so, for example, especially late in the season, we’ve had extremely low vertical wind shear, which is one of the reasons why we’re seeing hurricanes in November to look at hurricanes you expect in September because the shear has been so low. And so, that’s one of the things that we look at when we’re doing these two-week forecasts. So, we do six of them in our final two-week forecast.
We put out around the middle of October because climatologically, that’s when the season is really wrapping up. And of course, this year, we couldn’t put out a seventh one just given that November was more like October or September. But certainly, obviously, the late season was really, really active.
And to me, that’s really what stood out early on. We had a lot of storms, but not that many strong hurricanes, except for, obviously, the most notable one being Laura. But then, once you got to October, overall, maybe not as many storms, but the storms that formed were much stronger.
And especially, obviously, Ada and Iota were kind of the exclamation point on just, you know, it turned out to be a really, really active late season. There’s a lot of comparisons to 2005 this year. I’m trying to remember back 15 years.
Sometimes, it’s hard for me to remember back 15 minutes. But remembering back 15 years, didn’t we have one or two storms in December? We did, yes. You can get storms until the hurricane season officially ends November 30th.
But hurricanes don’t necessarily respond to the calendar year. I mean, hurricane season doesn’t start until June 1st. We obviously, we already had two storms prior to June 1st.
And our third storm formed June 2nd or 3rd, crystal ball, this year. And we also, I was looking back, we also had another area that the Hurricane Center was monitoring in late May and gave up to like a 60% chance of forming. So, we almost had four storms by June 3rd this year.
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So, it was a very, very active early season. And then, obviously, the season has gone on through mid-November. And then, you know, they’re still monitoring areas out there now.
And just because November 30th is the official end of the season, it’s not like the Hurricane Center packs up and leaves and, you know, anything in December. You can get storms in December. It’s not very common, but it does happen.
And every now and then, you can get hurricanes in December. So, basically, if it, whatever gets, whatever’s there through December 31st, that before, before the, you know, they drop the ball in Times Square, that counts for 2020. And then, anything else will be tacked on to 2021.
So, really then, if we have something June, January 2nd, it’s the first name off the 2021 list. Correct. Yes.
Yep. Yeah. Yeah.
That’s just the way it works. It’s, it’s, it’s kind of arbitrary. You could argue January should be more along what’s in 2020 than 2021, but it’s kind of hard because it’s like, well, how do you, you know, it’s not a very common occurrence, but in 2016, we had Alex in January.
So, it can happen really early. It just depends on the year. And I’m sure all people believe with 2020 going the way it’s gone so far that anything’s possible, Phil, for the rest of the, the rest of the year.
And hopefully, things will be different in 2021. Let’s talk about 2021 a little bit. I know it’s way early, but do you see any major atmospheric changes, a La Nina, El Nino, whatever, where we might see a significant difference in the 2021 season than what we saw this year? Yeah.
I mean, obviously the obfuscating 30 storms again are very, very low just because you could have, so when we do our forecast, the primary metric we forecast is this accumulated cycle and energy metric. And then, basically, what we do from that is we take kind of, okay, historically, when you have an ACE, say, of 180% of normal, how does that break down? How many storms, how many hurricanes, how many major hurricanes? And if you look at our forecast from this year, then you look at the ACE forecast, the ACE forecast are really close to being what actually observed, but the number distribution was very different. We had a lot more storms, but the longevity of the storm was shorter.
So, you could, for the same environment, you don’t necessarily know exactly how that’s going to break down. You know, it’s going to be very active, but whether you get a whole pile of storms that are weaker or shorter lived versus fewer storms, but longer lived. And so, the kind of the classic example I give is 2004 and 2005, both very active seasons, very devastating for the US, but broke down very differently.
When you look at that ACE metric, they were very similar. 2005 had 28 storms, 2004 only had 15. But if you look at the ACE, it was very similar, and that’s because 2004 had several long-lived major hurricanes, most notable being Hurricane Ivan, which basically hit the ground running off Africa, went all the way across the Caribbean, and then ended up making landfall in Alabama.
But if you look at 2005, we obviously had, we had four Category 5 hurricanes. We had Dennis, Katrina, Rita, and Woma, but most of those storms didn’t last super long. They were very strong, very intense, but like Katrina, wasn’t a hurricane for that long.
It formed near the Bahamas, went through Florida, then really ramped up in the Gulf of Mexico. But once you’re in the Gulf of Mexico, it’s not that, you don’t have that many days before you’re going to be hitting something. So while Katrina was a very, obviously an extremely intense storm, in terms of those aggregate statistics, it didn’t generate a huge amount just because it wasn’t out there very long.
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So it’s hard when you’re doing it on a seasonal forecast to know, you can say, okay, we know it’s going to be an active season, but whether it’s going to be like this year, where there’s just a tremendous number of storms, and not necessarily as long lived, or you’re going to have fewer storms, but that they’re longer lived. And so that’s something that’s, I would say the odds of that in 2021, of having other storms is very low. But, you know, right now we’re headed into a moderate to potentially even strong La Niña this winter, which is colder than normal water in the tropical Pacific.
One of the reasons why we saw this active late season was likely the La Niña, because La Niña tends to reduce the vertical wind shear, as we talked about before, too much shear tears apart the hurricanes. This year we tend to have very low shear, especially late in the season. Typically when you have a strong La Niña, the odds of going all the way back to a strong El Niño for the fall and summer and fall is fairly low.
So from that perspective, you say, okay, if we’re not going into a strong El Niño, or a moderate to strong El Niño, perhaps then the odds for an above average season next year are also still elevated. But obviously there’s a tremendous amount that can change between November 30th and June 1st. So we put out a very short discussion.
In a couple of weeks we’ll do a discussion about the hurricane season, but then we’ll go into a lot more detail with our first formal forecast with numbers in early April. And also remember Dr. Bill Gray always used to talk about, you know, historical factors. When you look back over decades, we see these rises and these falls of seasonal activity.
And if you look back just the last six years, if we go by that 10 or 11 average number of storms a year, we’ve had this increasingly number of storms each season. Are we in an upswing of activity on a larger scale perspective? Yeah, we’ve generally been in a very active era for Atlantic storms since 1995. Since 1995 in general, seasons have been more active.
So when it comes to the number of storms, one of the reasons why we’re seeing an increase in the overall number of storms in say the last 30-40 years is due to the fact that we have improved observational capabilities. So that’s not going to necessarily change your number of major hurricanes or your number of hurricanes. Even in the 80s we knew where the hurricanes were, but these kind of really weak marginal storms that are storms for a day or a day and a half, these are storms that Chris from the Hurricane Center calls the shorties, storms that last two days or fewer.
There’s a large increase in those. And so a lot of that is just improvements in technology. However, even if you say get rid of all those short-lived storms in 2020, we still would have been in the Greek alphabet.
So this year obviously was still incredibly active no matter how you look at it. But that’s one reason why we forecast the number of storms that we really like using say even just the number of hurricanes or accumulated cyclone energy, because it tends to kind of smooth out any of those increases that are just due to observational factors or basically an improved observational network. But certainly 2020, definitely a very active season no matter how you slice it.
And again, since 95 in general, the Atlantic has been in an active era characterized by warmer water in the Atlantic, so more fuel for the storms, lower shear, more unstable atmosphere in 2020 is kind of a classic example of what you get when you have one of these active era kind of years. We had a very active mid-September. We had storms popping up all over the place.
We had three storms forming today. And then obviously the very active late season is a classic example of both an active overall season but also a strong La Niña, which really helps to ramp up your late season storms. Seems like everything checked the box this year to make it just one of those seasons.
Dr. Phil Glotzbach with Colorado State’s Tropical Meteorology Department. Thank you so much. We’ll be on our edge of the seat now as we get closer into the spring and start hearing some of your preliminary forecasts for 2021.
And then of course everybody should stay tuned your typical forecast that comes out the 1st of June as we look at the season starting and underway for next year. Thanks so much Dr. Glotzbach for being part of the Disaster Recovery Roundtable. Sure, thanks so much Greg.
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