Peak tropical storm year – 2005 – all downhill from there

In a multi-national collaborative study published August 22, 2018 in Science Advances, climate simulations and subsequent analyses of tropical cyclone activity were led by the Commonwealth Scientific and Industrial Research Organization (CSIRO), the University of Melbourne and the Barcelona Supercomputing Center (BSC). Project leads used climate models to estimate the maximum number of tropical cyclones that might occur in the North Atlantic in the current climate.

They found the record number of tropical cyclones that occurred in 2005 (28 storms) is close to the maximum number that might occur in this region given existing climate conditions. This information is useful for risk management because the year 2005 has already been extensively studied and its tropical cyclone hazards and risks to infrastructure are well known. Thus, it could serve as a tropical cyclone risk benchmark for future hurricane seasons in this basin.

The year 2005 was certainly the biggest year for tropical storm and hurricane numbers in the Atlantic since the 1940s and, by some measures, the biggest for at least 150 years. There were so many tropical storms in 2005 that the U.S. National Hurricane Center ran out of tropical cyclone names; by late in the hurricane season, they resorted to calling tropical storms by letters of the Greek alphabet. It is of considerable interest whether a year like 2005 might occur again, and how often, not only for hurricane forecasters but for emergency and risk managers throughout the North Atlantic region.

In this study, thousands of years of climate model simulations were examined to see if they could produce climate conditions more favourable for tropical cyclone formation in this region than occurred in 2005. The statistical relationship between climate conditions during the tropical cyclone season and tropical cyclone formation has been previously calculated using a variety of indices, which were examined in this study. The year-to-year simulated variations of these indices in the climate models were compared to total observed tropical cyclone numbers in 2005, but the models only exceeded the observed 2005 numbers rarely, about 1% of the time, and maximum index values simulated in the models were still comparable to 2005 numbers.

Lead author, Dr. Sally Lavender of CSIRO said “It’s hard for the Atlantic climate to generate a lot more tropical cyclones in this region than occurred in 2005. Even when we looked at thousands of years of climate model simulations, they didn’t really indicate a convincing possibility of many more tropical storms.”

While the study does provide an estimate of the maximum number of tropical cyclones in the Atlantic, there are important remaining issues. “The indices do show generally good relationships between climate and tropical cyclone formation rates, but they are not perfect,” added Dr. Louis-Philippe Caron (BSC), “and the climate model simulations of the Atlantic climate could be improved.”

The work was sponsored by the Risk Prediction Initiative (RPI) and had further input from Stockholm University’s Bolin Centre for Climate Research. Dr. Mark Guishard of RPI said, “This work is important in the context of risk management, so it’s not surprising that our industry sponsors were keen to support this research.” RPI is a science-business partnership based at the Bermuda Institute of Ocean Sciences, supporting researchers in academia and providing independent insights for decision makers in the insurance industry.

The study also does not directly examine the potential for damage caused by the storms. Hurricane damage in a season is correlated with the overall number of hurricanes, but there is variation within those hurricanes as to the extent of that damage–an issue that Dr. Lavender and her colleagues plan on looking into in an upcoming study.


For more information about the Risk Prediction Initiative at BIOS, visit


45 thoughts on “Peak tropical storm year – 2005 – all downhill from there

  1. I wonder what the relationship is between the total number of tropic storms, and landfalling tropic storms.

    • The goal posts are being moved too rapidly to tell.
      A storm becomes a tropical storm if a satellite notices indications that the wind may be of tropical force for a very brief period. This continual observation has not been available for many years. Previously, it would have required a ship or aircraft report of sustained storm force winds.
      Similarly, hurricanes are now graded not by winds but by central pressure. A meteorological researcher obviously thought that this was a good scheme. However, there does not appear to have been any thought to the pressure gradient which is what provides the damaging winds. Irma a huge storm – the size of Florida – may well have had strong winds in the Caribbean but by the time it reached the Keys the wind strength was nowhere near the claimed Category 3 status.

      Continual change of the metrics and their units and recording rate has resulted in a total loss of reliability. In consequence the number of tropical storms in the 1990’s may be a whole lot less than in the 2010’s purely due to the method of assessing weather systems and the continual observations.
      The question is – is the obfuscation deliberate? We need an approach to Atlantic storms that matches the approach to measuring sunspots in order to maintain a standard metric.

      • Totally agree. Depressions that would not have been designated Tropical Storms even five years ago are now getting names. And the 1 minute sustained windspeeds the Hurricane Hunters are coming up with are higher than those we see when the hurricane passes over buoys or land stations. Thus both the count of tropical storms and hurricanes and their strengths are being inflated these days.

        Just a note about the current Atlantic season. We’re coming into the peak period for development and conditions are changing to more favorable conditions for development so the probability of strong storms developing in the MDR, Gulf of Mexico, and Caribean is increasing and will do so for the balance of the season. Bottom line is we aren’t out of the woods yet and the probability of major hurricane development is rising.

      • Couple of years back when they were desperate to break the cat 3 hurricane drought. Whichever hurricane it was was shadowing the FL. coast. cat 3! cat 3! cat 3! I was suspicious because it seemed to defy physics that so little wind on the FL coast could spin up to cat 3 in that little distance. Lesson for now is that I go directly to buoy data. Buoy data even on the hot/right side was barely a hurricane. Did the same for Lane. Nothing spectacular in wind speed at buoy level though I’d expect some pretty wild flows around the mountains. Sucked that Lane slowed down. Nuclear alert, Volcanoes, Hurricanes Aloha HI.

  2. I am unconvinced that this is a robust study. Since they can’t reliably predict the current hurricane season, why do they think they have the physics correct to predict the maximum possible? That seems like a much more difficult test of their model. And one that can’t really be tested by historical data.

    • “Even when we looked at thousands of years of climate model simulations………..”
      Much of it is based on climate models which, as even the IPCC admits, are close to useless, as weather and climate are largely chaotic.
      Instead of relying on these fantasy playstation games, they could have saved a lot of money by tossing a coin. If their conclusions on the limits of the number of hurricanes per season is vaguely correct it’s probably due more to blind luck than skill.

      Still, to their credit, they didn’t “adjust” the results in order to predict yet more global warming doom.

  3. tropical storms 28…..or the big scary word they like to use….cyclones
    IIRC….18-20 of those were not hurricanes..and maybe about 4 actually hit something

    • Ren
      Go to this site:
      Scroll down to the free videos and click the one on the right. Joe Bastardi is far better than most at forecasting this kind of thing and what he is saying conflicts with your analysis. He thinks development will most likely occur in the next 10 days from one of two possible disturbances currently in the MDR. Waters have warmed in the MDR, Gulf, and along the east coast of Florida. Dust still coming off of Africa, but not as much as there was. And perhaps most importantly, the precipitable water level in the MDR is now much higher than it has been at any time during this season.

  4. OT a bit but related; has anyone seen that new hour-long piece by SCETV (South Carolina Educational TV) called “Sea Change” ? (In Sea Change, South Carolina Educational Television presents diverse perspectives on the impacts of sea level rise and other environmental changes on the entire Eastern Seaboard, as experienced and anticipated in Coastal South Carolina and Georgia. Narrator Patrick McMillan takes viewers from the sands of Hunting Island State Park to cities, towns and communities up and down the coast. ) It is a typical alarmist piece, lots of scary predictions and some whoppers, and send us money. It is mainly anecdotes, no science, pretty lame.

    • John, I didn’t see the documentary but I will bet that the discussed the tragedy that was going to befall the barrier islands and the impact further inland if barrier islands disappeared. Did they bother to mention that barrier islands have always come and gone and did so long before the beginning of the Industrial Revolution?

      I got to sit through a lecture on the East Coast of Florida. The geologist had searched the archives for aerial photos and satellite imagery of the coast. He had managed to put them into comparable imagery. It was amazing to see. He showed the dramatic changes in the coast line just since the first airplane flew with a camera taking pictures of the coast.

      I also worked for about five years with a sixth generation commercial fishermen along the SW coast of Florida who was in his late 60s at the time. He gave us a great lesson in the dramatic changes in that coast line just in his lifetime. Then for about a week his father joined us and took us even farther back in time.

  5. The hurricane drought didn’t start in 2005, but 2006. The 2005 Atlantic basin hurricane season was extremely above average to the end of the year with it’s last hurricane in December and it’s last tropical storm going into early the following January.

  6. This summer I learned about the relationship between a hot European summer and hurricanes, a hot European summer prevents the west African Atlantic from heating, resulting in a low hurricane number. A wet European summer therefore means less clouds over the west African Atlantic and a warner ocean meaning more hurricanes.
    The record breaking hurricane year 2005 removed so much heat from the west African Atlantic that the following summer in Europe was record breaking hot. Pinot Noir 2006 is excellent.

  7. One slim possibility from my perspective is that the high number of TCs in 2005 had something to do with the warm trend which started in 1976/77 coming to an end in 2006/07. As I read the above post I wondered “When was the last similar high year for TCs”. Then that is stated as happening in the 1940s. Which brings me back to how I view the shift points of the climate. The climate also shifted from warm to cool in 1946/47. So is that the connection between 2005 having a high count as well as the 1940s also having a high count? If so, then the next similar high count would occur approximately in the mid to late 2060s which should be the next shift point from a warm trend back to a cool trend.

  8. Hurricane damage in a season logically should relate to the number of landfalling tropical storms. However we know that there are those on the AGW side of the aisle that use total dollar value and even some of those numbers are hinky. They seldom discuss the dramatic expansion of coastal development all over the world but especially in the Americas and most especially in the USA. Example, in 1959 there were about 3 million residents in Florida. Many of those lived inland away from the coast because of the frequency of hurricanes from the 1920 through the 1950s. Today there are over 21 million people with a large percentage of the population living on the coast.

    When I began my professional career places like Cozumel and Cancun were little more than coastal villages. Today they are major resorts.

    My questions relative to the models that were used are (1) did the models all assume that carbon dioxide was the primary driver of climate? (2) How in the heck did they model the influences of the Atlantic Ocean on climate? (3) a more general question, how are the oceans dealt with in any of the climate models? Oceans are indeed a primary driver of tropical cyclone development.

  9. There are many factors determining the number of storms which form, but the main one that counts is wind shear.
    If wind shear exists storms get torn apart in hours, or else can never spin up.
    No one has mentioned 2004, which is when the burst of hurricanes, and strong storms, and increased numbers, started.
    In fact it was a particular week towards the end of 2004 Summer.
    It was like someone threw a switch, and every area of persistent cloudiness developed.
    At that point random factors largely predominate: Which way are steering currents pushing the storm, what is in the path of the storm given location and vector, and how many people live there, what is the topography, affluence of the area of impact and hence property value, has the area hit been hit recently, which if the answer is yes means that structures have been rebuilt or strengthened to higher standards, and so forth.
    IOW…the amount of damage is largely random chance. There is no way to determine it in advance, even if accurate forecasts of sheerless zones exist, or even if someone sent a message back in time stating number of storms that will form that season, because you need something to start with…the persistent area of cloudiness/low pressure, and this is random.
    The same thing happens on smaller scales: Here in Florida this time of year we have daily thunderstorms that start as cumulus and towering cumulus and grow into cumulonimbus.
    But no one can say ahead of time exactly where a thunderstorm will pop up…it is simply too random due chaotic factors.
    I am certain that to a large degree the best that will ever be achieved is to have huge numbers of accurate data points, and continuous real time imaging that is watched very carefully, so that regions of potential formation can be assessed constantly, and incipient storms observed as soon as possible.
    Anticipating where they will then travel, and grow or diminish, becomes a function of data collection and raw computing power. Even then random factors will keep it a guessing game ,with high certainty possible in certain situations and over a certain distance and time horizon, but low certainty in other such circumstances.

    When someone thinks they can predict with accuracy where and at what time the first cumulus cloud of the day will form, over which house or hayfield, then maybe there will be an ability to anticipate at the outset of any particular interval, exactly or even roughly what is going to happen, before it does happen.

    • Further hindering efforts to protect lives and property while minimizing needless disruptions, are a myriad of other factors such as the tendency towards exaggeration and/or alarmism in certain quarters, and complacency and confidence in other quarters.
      Some forecasters are clearly exaggerating not just the strength and windspeed and damage potential, but their confidence level in the ability to prognosticate accurately.
      Some overestimate, and some underestimate.
      After a string of successful and accurate forecasts, prognosticators can forget or neglect to issue uncertainties along with their forecasts.
      And vice versa…a string of storms that defy predictions can lead to overly broad warnings and evacuations.
      Neither is desirable, and there are many consequences to both to grave of a warning, and being too phlegmatic.
      Evacuating people from wide areas when it turns out to not be necessary can be disastrous all by itself, not just by people stuck on roads under unpleasant and even deadly conditions of heat or lack of supplies, but also because people will refuse to evacuate at futures times when it is best if they had done.
      It is very important for people issuing evacuations to take into account what will happen to people once out on the road with supplies dwindling and workers themselves evacuating, and also to consider the ability of structures to withstand what is coming.
      This last, I think, gets too little attention: Last year in Irma we had millions evacuate homes that had every ability to withstand even catastrophic winds speeds. May of these people had severe difficulties out on the road and would have been better off at home.
      In short, it is complicated and difficult and there is a certain amount of unavoidable “damned if you do” and “damned if you don’t” to warnings and evacuations.
      Living in hurricane country is dangerous, period.
      Living near the coast in hurricane country borders on insanity, and at some point a huge price will be paid for lax attitudes to danger.
      Being too nervous and issuing excessive warnings may make that eventual day worse, because people will become accustomed to ignoring breathless warnings.

      BTW, in a totally unrelated but analogous disaster waiting to happen scenario…there seem to be an awful lot of people in places that are going to, at some point, have a catastrophic earthquake and/or tsunami, or a volcanic eruption. I wonder how many people in the Pacific Northwest have no idea what a lahar or a pyroclastic flow even is, or know exactly how certain an eventual tsunami is, or if people in many places have a true appreciation for the certainty and possible size of The Big One that will hit their area someday?

      There are a ton of people who have finished college at this point in time who have never seen a large volcanic eruption or earthquake strike the US or any place they are familiar with.
      I am certain many of these people have never for a minute taken the risk they face seriously.

  10. It’s hard for the Atlantic climate to generate a lot more tropical cyclones . . .” [Sally Lavender, Aug. 2018]

    I feel trouble is brewing in the North Atlantic in 2019.
    Just saying.

  11. Sigma Xi is having a symposium (Annual Meeting and Student Research Conference
    October 25–28, 2018) on Big Data, one session on Energy, Climate, and the Environment

    American Scientist just put out an issue on Big Data, nothing on climate, mostly space.
    I have been concerned and have posted about Sigma Xi’s administration’s advocacy without member input. American Scientist has maintained standards.

    Keynote Session on Energy, Climate, and the Environment by William (Bill) Collins,
    Director of the Climate and Ecosystem Sciences Division in the Earth and Environmental Sciences Area of Lawrence Berkeley National Laboratory (LBNL); Professor in Residence in the Department of Earth and Planetary Science at University of California, Berkeley; and Director of the Climate Readiness Institute and David Reidmiller, Director of the National Climate Assessment by the U.S. Global Change Research Program, White House Office of Science and Technology Policy

    Two sessions, Global Parameterization of Climate Change Indicators —
    Changes in carbon intensity (defined by the ratio of CO2 emissions to GDP), and Reduction of a Manufacturing Plant’s Electricity Demand During Grid Consumption Peaks with an Energy Storage System Managed by Neural Network-Based Big Data-Fed Demand Forecast and a Decision Model.

    There is also a session on Grant Writing and one on Science Communication. Did not see hurricanes but could be in there somewhere. I wonder how many in the symposium have been in a hurricane.

  12. This is an interesting paper as it starts to identify the maximum immediate energy available for release in the Earths system during a recognized period, albeit with an Atlantic focus. It makes a nice change from the from the dull repetitive drone, focused on temperature anomalies as the only measure of energy. It provides another perspective on how earths energy is utilized. 2005 Arctic sea ice was lower than both 2004 and 2006, another measure of the energy output.

    One day when atmospheric science matures, there will be a minimum of 5 or more key performance indicators to measure the current energy state, and how it was spent that year / season. Temperature anomalies are simply measuring the energy as heat without reflection of the reduction in other values such as cyclones, sea ice reduction, ice increase etc.

    • You will note that since 2000 Global ACE has reduced, Arctic sea ice minimum was reached in 2012, Antarctic sea ice maximum in 2014, the ozone hole is declining. These are all relevant to earths energy state. There is a big picture based on that same energy, used differently and influenced by annual variations. One value (temperature anomalies) is meaningless.

    • OzoneB

      Temperature is a nearly useless metric for any purpose involving energy unless coupled to other things, like water content. As others have pointed out, it is the enthalpy of a system that is of interest, not its temperature.

      An exception to that is the temperature of the ocean when referring to cloud feedback, but that is a special condition because everything else is fixed in that ‘thunderstorm’ discussion.

      A slightly higher temperature matters not a whit unless the local water vapour is also reported, per site, so as not to unduly influence a system energy calculation. Reporting the Humidex at each location instead of the temperature would be more useful in ‘telling us something’.

  13. The climate didnt change at all between 2005 and 2006 yet hurricane numbers swooned and did so for a dozen years! This tells anyone with game that the models are hopelessly inadequate and there seems no guidance on how or if there is a prospect of improving them. Yet they tell us how useful theyve been.

    All the major disasters spawned in the atmosphere show a decided disdain for modelers and forecasters offerings. With huge bands of cold water choking up the lanes, I was gobsmacked by NOAA’s Atlantic hurricane/tropical storm forecast for 2018! I suddenly realized a mining and metallurgical engineer’s common sense and cursory look at the playing field is more skillful than the well paid, one job specialists with the Govmint. Lift your heads from the XBox screen and look at the situation on the ground. At least modify the forecast with a coefficient drawn from reality.

  14. Al Gore made a big deal about 2005 having more than 21 tropical cyclones requiring NOAA to assign Greek letters to 7 additional storms, suggesting it was a new normal with much worse to come.

    NOAA’s use of Greek letters was “the first time in history,” as Gore says, but the practice of naming storms only goes back to 1953 ( Hurricane detection capabilities have improved dramatically since the 1950s, to say nothing of prior decades.

    So although 2005 had a record number of identified Atlantic basin hurricanes, this does not tell us much beyond the fact that 2005 was a very active hurricane year.

  15. Every time I read one of these articles, i get disgusted by the lack of scientific due diligence. NOAA, and most likely similar agencies in other countries has extremely good historical records of hurricanes, including normalized data (for observations, etc) and could have answered most of the questions presented in the study with about 5 minutes of research. I guess the question of what is the maximum number may be a reasonable question to ask, but they should be comparing the historical record published by NOAA to their calculations to determine if its reasonable. When I studied science, one of the required steps was to actually do research to see if my calculations agreed with results published elsewhere

Comments are closed.