Atlantic Hurricane Season 2008 Withers on the Vine

Atlantic Hurricane Season 2008 Withers on the Vine

The North Atlantic hurricane season has nearly come to an end. As November progresses, the chance of another storm developing becomes smaller. Climatology (last 60 years) tells us that roughly 4 in 10 years see a November storm formation including 4 in 2005 (Beta, Gamma, Delta, Epsilon), Hurricane Michelle (2001), Hurricane Lenny (1999), and Hurricane Kate (1985). Jeff Masters from the Weather Underground has an image of previous early-November storm tracks especially clustered in the Western Caribbean.

So, what has the 2008 season wrought in the North Atlantic and how well did the seasonal prognosticators fare?

Even with the expected post-season tinkering of the real-time storm tracks by the folks at the National Hurricane Center, we can provide fairly accurate preliminary numbers. The community at Wikipedia constantly updates many interesting facts about the ongoing 2008 hurricane season.

Total Named storms (34 knots + one-minute maximum sustained winds): 15

Total Hurricanes (64 knots +): 7

Total Major Hurricanes (96 knots +): 4

Accumulated Cyclone Energy: 132

The respective forecasts made by CSU (Klotzbach and Gray), NOAA, as well as the UK Met Office came in quite close to the actual experienced storm activity. Before handing out trophies, please keep in mind that forecast “skill” is a function of many forecasts over longer time periods. Each of the forecasting outfits prefers to use different techniques and variables to calculate their storm numbers, so we will have to wait until each completes their post-season analysis to determine if they were “right for the right reason” or got lucky.

Now, to answer the question: how active was the 2008 hurricane season, we need to define climatology. This is where the tricksters can play pranks on the public. Where is the beginning point of the analysis? How well do we trust the frequency and the estimated intensities of each storm? What metric do we use – number of tropical storms, number of hurricanes, ACE (accumulated cyclone energy), Power Dissipation, or perhaps some complicated statistical measure? All of these questions are entangled in the debate surrounding whether anthropogenic climate change is indeed a modulating influence upon current and future Atlantic hurricane activity.

A well-accepted metric which convolves storm frequency, intensity, and duration is called accumulate cyclone energy (ACE) and is calculated very simply: take the maximum sustained winds reported by the NHC every 6-hours for all storms (> 34 knots), square this value, and sum over the entire lifetime, then divide by 10,000. In 2007, even though there were also 15 storms, the ACE was only 72 compared to 132 for 2008 with the same number of named storms. This is partially because the storms in 2008 were much longer lived especially Bertha.

Here are three different views of the Atlantic hurricane climatology depending upon what period you look at. The data is from the NHC Best Tracks without any corrections to the intensity data.

Links to two other time periods:

1978-2008

1944-2008

Thus, since 1995, Atlantic hurricane activity measured by ACE is hugely variable with feast (i.e. 2005) and famine (1997). 2008 ACE is nearly equivalent to 2006 and 2007 combined, but about half as what was experienced in the record 2005 season. The choice of 30-years is a particular favorite for many researchers in the tropical cyclone community (1978-2007). The second image clearly shows the nearly stepwise increase in ACE between 1994 and 1995. In this reference frame, 2008 ranks as one of the more active years of the past 30. Now, back up to 1944, when admittedly the intensity (and detection) data is somewhat less reliable. However, since the ACE metric is the convolution of an entire year’s worth of storm lifecycle information, and is most sensitive to higher wind speeds, the track data points prior to satellite observation (~1970s) are probably sufficient for this exercise.

Final verdict: When encapsulated in the recent active period in North Atlantic activity (1995-2007), 2008 experienced normal or expected activity as measured by ACE. In terms of a long-term climatology, either the last 30 or 65 years, 2008 is clearly an above average year.

Note: for the Climate Audit seasonal forecasters, especially those that showed exemplary skill (however you wish to measure it), please fill us in on your methodology and perhaps provide guidance for 2009. Or, for those feeling shame about being “blown off track”, time to think of good excuses.

Also, a new Science perspective has been published by Vecchi et al. (2008) entitled Whither Hurricane Activity? More on that later…

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45 thoughts on “Atlantic Hurricane Season 2008 Withers on the Vine

  1. I believe the scaremongers are crying in their beer. No horrific Cat 5 hurricanes to report and no damage to property and deaths… jeez, can’t sell global warming with such good news… 😉

  2. Here in South Florida we’re happy to have this season fading. Apart from the storms themselves, the biggest issue for us is that our insurance rates are constantly threatening to go up (even more than they already have) and the annual predictions of above-average seasons are constantly being used as ammo against us homeowners.
    Several insurance companies have already pulled out of Florida. Others threaten to do the same if the state doesn’t permit them to raise premiums to their satisfaction.
    Front and center of the discussion are the forecasts for upcoming hurricane seasons by various climatologists. Those predictions have a direct impact on family finances all over the Southeast coast.
    There have already been lawsuits, and I keep hearing rumors of more in the works. These are mostly tactical, i.e. not trying to intimidate scientists, but rather to prevent anyone (insurance companies) from using some climatologist’s honest best-guess from being treated as fact.

  3. Richard deSousa, you missed the part where force is not only on the 1-5 scale but also is about diameter. They learned about that in and around when Ike caused damage in the Caribbean, killing many tens and mainland fall e.g. at UMTB Galveston alone a billion US damage was caused.
    If you think that was good news for the denialists, good for you.

  4. Sekerob, there is no objective proof that any recent hurricanes are anything out of the ordinary. Nothing to see here–move along.

  5. I would imagine most regular people who live in places where hurricanes can hit consider each season by the number of times we have go into final storm prep mode. How many times did I have to stop everything else and secure my residence or business and then get them back to normal after the threat is over. 2004 I did that 5 times, a real pain in the butt. This year only once and then only a minimal effort, a good season. But in Haiti it was a different story, a really bad season. So how well do I think the predictors did, honestly I don’t even bother to check. I prepare as if it will be the mother of all hurricane years and go from there. But Dan Lee has made a great point. Insurance companies have been using these predictions to set rates. And as Dan said, there are real life consequences to these predictions. So while you all chart your numbers, calculate your ACEs and delta this & that to rank the years and argue your points, it is only your personal pride that is hurt if you come up short. Not so for some of the rest of us.

  6. I wonder what all these ridiculous predictions and measurements would look like with the slight breezes factored out? You bet there are real life consequences of all this gibberish, and all this inflation of reality. And people pay dearly for the crap. I am in South Florida and all the insurance rates do is go up.
    We did nothing this year … there was no reason to do anything.
    When they do the predictions, I wonder if they take into account things like in the past, like say the 1900 Galveston hurricane, they new it was coming when it got there. So how many hurricanes out in the open ocean didn’t they know about? There are plenty of instances in the last 100 years where there was no warning to speak of about landfalling hurricanes. So how do we have any way of knowing the records are apples and apples.

  7. Actual, there is allot to see and learn “objectively” and was responding to the “I believe the scaremongers are crying in their beer. No horrific Cat 5 hurricanes to report and no damage to property and deaths… jeez, can’t sell global warming with such good news… ;)”
    There were many deaths particularly on the isles from a “2” and many billions of damage… not something to celebrate. The Saffir-Simpson 1-5 scale as the NHC has come to realise is wanting.
    How did Ike cause the massive damage as a 2 opposed to Katherine being 3?

  8. One of the unfortunate consequences of people living in nice locations (lifestyle-wise etc) and the continuing development of coastal areas (happens here in Australia more than in most countries) is that the incidence of damage, and the value of damage increases.
    Can’t blame the insurance companies for putting up their premiums.

  9. sakerob…
    First, you are completely missing the point, which is that count + intensity is what is used to sell global warming. Advocates of same tend to claim that the count of storms will go up; others claim that the counts will be similar to today but more intense; yet others claim both. It’s good to see discussion of the data. What *did* happen this year vs the historical record? Is it unusual? If so…. why?
    Second, I don’t recall seeing size as being what I’m to look for, and I’ve been watching weather news for about 35 years. Yours is the first mention of size I’ve seen. Fascinating. How could I have missed this?
    Third, the purpose of such a blog post as this one is to examine the ability of the forecasters to forecast accurately, which tells us about how well their models work. This is interesting regardless of one’s take on global warming. Refer to my point #1 if you have difficulty understanding this.
    Fourth, your comment reads like “you idiots forgot to factor in X, pretty typical of dumb denialists” which I find amusing. Condescenion AND missing the point AND name calling tend to go hand in hand, and your contribution wasn’t an exception. Nicely done.

  10. I will retire in Texas, on the gulf coast, in spite of the hurricane risk.
    Why?
    Because a hurricane only lasts a few hours. Winter lasts 8 months.

  11. It would be more interesting, I think, to see this bar graph made into a line graph. In something cyclical like this it is more helpful to illustrate the highs and lows with that type of graph rather than the bar graph. You can kind of already see that if you follow the tips of each of bar from one to the other. It seems to have some fairly wild swings, both up and down. I know there was a reason for starting with 1995, since I am familiar with Gray’s most recent work in 2008, but can we get something up to 2007 at least? Also could we delineate but also include non-active years of the AMO? That would help for contrast.

  12. Sorry, I guess I did not read carefully enough. Plenty of data. Just lines over bars would be nice.

  13. Really, and I’ve only been reading up an all for a little while, not only the sources we ‘like’. You missed more, to include the impact of [Saharan] desert sand/dust blown up over the Atlantic which works to suppress hurricane forming… it’s not only “watching the weather”
    What you further read into what I wrote is classic… thumbs up.
    Tom in Florida, totally agree with you.

  14. Not just Florider (sic) but in Cape Cod MA where I own oceanfront property, the insurance companies used the exaggerated hurricane predictions to cover a massive insurance rate increase mid-decade. Thank you algore for the first of many gaffes where you cost me money.

  15. Kohl Piersen: “Can’t blame the insurance companies for putting up their premiums.”
    Nor do I, unless they use ridiculous models that were based on a simplistic notion that “as SST goes up the number and intensity of hurricanes increases” and then get away with it because of people like Algore and his legions of fear mongers.

  16. Previous post and this for G Alstum: Possibly the comparison of a 1.6 litre 4 cylinder doing 9000 rpm versus a 5 litre V6 doing 2500 rpm would be a good analogy to “size matters”. Ike had massive surprises as my friends in Galveston and Houston came to find out.

  17. In 2008, not a single Taiphoon has landed here in Japan. This has happened only 3 times since 1951 when they started to keep such records in Japan. There were totoal of 18 Taiphoons recorded this year (average is 23.1). GW was to bring increase size and number of Taiphoons.
    A good site to track information on Taiphoons in English is: http://agora.ex.nii.ac.jp/digital-typhoon/index.html.en

  18. Sekerob makes a good point about size. When Charley hit Punta Gorda in 2004 it was a very compact, small storm with top winds above 145 mph. I live 22 miles as the crow flies from where the eye wall came ashore and traveled up Charlotte harbor. I experienced winds of around 50 mph and had very little damage. As I drove to Port Charlotte a couple of days later to look in on some friends and customers, I didn’t notice much damage until I got about 3-4 miles from the harbor. Then within a very small radius there was total devastation. The angle of landfall is another factor as Charley took a hard right turn to make landfall which resulted in a very small storm surge for a Cat4. Ike, a Cat2, had days to travel across the Gulf allowing a massive dome of water to build under it and then hit head on into the Galveston area destroying everything. Lastly, I believe because there has been so much ado about Cat4s and 5s that inexperienced people do not understand that even a minimal Cat1 can do lots of damage and therefore tend to poo poo anything but the “big ones”.

  19. Katrina damage was mainly due to failed dikes. Flood damage, not direct storm damage. Haitian losses due to ill-preparations for a typical storm. Hurricane-related losses are not a direct function of wind speed in most cases. Many other factors at play.
    Like the fabled grasshopper who fiddled while the ants prepared for winter, those who blame the weather/climate are often proved foolish.

  20. This was the worst hurricane season on record for Cincinnati — Ike came through here with 70+ mph winds and knocked out my power for two and a half days. Some folks were out for a week.
    We don’t get a lot of hurricane damage up here. Nobody predicted that one, I bet.

  21. I am just wondering where the evidence is that the size of hurricanes has increased? But whatever. It will take more than lack of evidence to end the Global Warming doomsday cult.

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  23. // Les Johnson (15:58:08) :
    I will retire in Texas, on the gulf coast, in spite of the hurricane risk.
    Why?
    Because a hurricane only lasts a few hours. Winter lasts 8 months. //
    But death lasts somewhat longer. I have been quite amazed at the accuracy of the science regarding the prediction of the path of these hurricanes. As these scientists can only be 90% accurate though why does anybody take any notice of them?

  24. Philw1776 and Tom in Fla – If that is the case then it is just profiteering and can’t be defended. On the other hand, maybe they’re just running scared, scared by the rubbish sprouted by Al Gore et al.
    Christian – “70+ mph winds and knocked out my power for two and a half days”.
    I’ve been in that situation in a small country town in Australia – BUT it was not a hurricane or a tornado or… it was just a few gusts of very hard wind and heavy rain in a thunderstorm. Such things happen regularly, but not in the same place. Perhaps that’s just a bit of weather.

  25. @MikeRossTky,
    Relative neutral ENSO conditions, PDO tending towards cool too, and 18 Typhoons sounds like a good correlation to “only” 18 “so far” in 2008.
    I did look up the http://agora.ex.nii.ac.jp/digital-typhoon/index.html.en
    and the ACE data they show lists:
    2004 – 29
    2005 – 23
    2006 – 23
    2007 – 24
    2008 – 18, [till Nov.1]
    Is this some form of support of GW not true? Looks to me like 2008, so far, is an anomalous year against a 58 year mean of 23.1, with the ’04-’07 period clearly having an above mean.

  26. Mike Dubrasich:”Katrina damage was mainly due to failed dikes. Flood damage, not direct storm damage. Haitian losses due to ill-preparations for a typical storm. Hurricane-related losses are not a direct function of wind speed in most cases. ”
    The Katrina damage you state was only for New Orleans. Coastal Mississippi and Alabama were destroyed by storm surge and wind directly from that storm. The news only focused on New Orleans. Same with this year. I was speaking with a medical office in Baton Rouge after Gustav hit them and asked how they were doing. They were hit really hard with severe wind damage, power outages and flooding. What made them really mad was that no one seemed to care. They were incensed that as soon as New Orleans was in the clear all the reporters went home and the story was over.

  27. The graphs would seem to correlate nicely with regime changes in the AMO, and one is reminded that the great Bill Gray was already warning during the blase ’70’s that an uptick in Atlantic tropical cyclone activity was a few decades down the road.

  28. Though it was an active hurricane season , I have to say that as far I’m concerned , I have never seen so many storms affecting so many countries in the caribbean , central america and the gulf region in one single year .

  29. By the way, Anthony, is that poster child ‘cane Floyd from 1999?
    Floyd didn’t look so purdy by the time it huffed and puffed its way up here to 40 N, but it dumped 15 inches of rain in as many hours on central New Jersey, and the ensuing Floydian flood (not Floydian slip) knocked out a major water filtration plant for two weeks.

  30. ‘…no damage to property and deaths.’
    Isn’t Texas still in the Union? How many missing and presumed dead on Galveston Island?
    It doesn’t take a Cat 5 or even a major hurricane to cause grief

  31. This was a fairly typical hurricane season, with typical storms.
    It will be the AGW promoters who seek to extract evidence supporting their faith from this.

  32. One thing to consider in re this last tropical season, is that many of the storms formed very close to land. One effect of this, e.g. with Faye, was that, even though upper level patterns were quite favorable for intensification, interaction with land, especially with mountainous Hispanola and western Cuba, inhibited development, while enhancing rainfall– sections of Florida got a half-year’s worth of rain in three days.

  33. It also seems, on the shorter term, that ENSO phenomena are reflected in the graphs: strong El Ninos correlate with decreased tropical cyclone activity in the Atlantic and La Ninas with increased activity.
    The opposite is true for the Southwest Pac, which leads me to wonder whether there are ACE figures available for the current typhoon season. The global ACE and its adventures over the past century would also be quite relevant in trying to grasp such cyclic patterns as can be discerned (Leif Svalgaard has wised me up on cyclomania as applied to systems with a significant chaotic input).

  34. ‘…so many storms affecting so many countries in the caribbean , central america and the gulf region in one single year .’
    How about one storm that, in a week or so, brought hurricane conditions to every one of the Greater Antilles, and then to every state on the Atlantic coast of the U.S. from Florida (both coasts) to Maine?
    That was Hurricane Donna in 1960–a year, by the way, with an anemic ACE.

  35. ‘Ike, a Cat2, had days to travel across the Gulf allowing a massive dome of water to build under it and then hit head on into the Galveston area destroying everything.
    Another important factor is the depth and configuration of the continental shelf just off a given target area.

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  37. It might be my imagination, but I’ve noticed pictures of the Earth from the Apollo missions in the late 60’s show a very cloudy Earth. Modern pictures from space show a very clear earth.
    Is there a difference in photo technology and filtering, or is there really that much less cloud cover?

  38. Pretty cool – a hurricane in the Carribean and a bilzzard in the Dakotas. I have no idea when that happened last. (BTW, the blizzard may not meet a rigorous characteristic, the temperature is above 20F. However, the storm is turning 10″ of snowfall into 10′ of drifts, and ready drifting is one reason for the cold temperature requirement.
    In the northeast, the NWS dropped the temperature requirement since coastal storms usually bring warm temps.

  39. According to Wikipedia, NOAA defines normaility in terms of ACE for tropical storms and hurricanes in the Atlantic basin as follow:
    “Measured over the period 1951–2005 for the Atlantic basin:
    Median annual index: 89.5
    Mean annual index: 102.3
    A season’s ACE is used to categorize the hurricane season by its activity. NOAA categorisation system[3] divides them into:
    Above-normal season: An ACE value above 103 (115% of the current median), provided at least two of the following three parameters exceed the long-term average: number of tropical storms (10), hurricanes (6), and major hurricanes (2).
    Near-normal season: neither above-normal nor below normal
    Below-normal season: An ACE value below 66 (74% of the current median):
    In the Above-normal case, ACE median ~ 1.15*ACE Medain, whereas, in the Below-normal case, 0.65*ACE ~ 0.74*ACE Median. This stikes me as rather odd. I would have thought the boundaries would have been more symmetrical. Can anyone help me, or direct be to a reference source that might help me, understand the reasoning for defining the categories this way?

  40. Re: My last message
    “In the Above-normal case, ACE median ~ 1.15*ACE Medain, whereas, in the Below-normal case, 0.65*ACE ~ 0.74*ACE Median.”
    should read:
    “In the Above-normal case, ACE Mean ~ 1.15*ACE Median, whereas, in the Below-normal case, 0.65*ACE Mean ~ 0.74*ACE Median.”
    Sorry about that …

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