2005 Hurricane Season in the North Atlantic Approached Theoretical Limit

By Nathaniel Scharping | August 22, 2018 5:44 pm
Hurricane Katrina, imaged on Sunday, August 28, 2005, near the peak of its intensity. Credit: Jeff Schmaltz, MODIS Rapid Response Team, NASA/GSFC)

Hurricane Katrina, imaged on Sunday, August 28, 2005, near the peak of its intensity. (Credit: Jeff Schmaltz, MODIS Rapid Response Team, NASA/GSFC)

2005 was a crazy year in the North Atlantic. That hurricane season saw not only the most tropical cyclones in recorded history for the region, it also spawned the lowest pressure measured in the Atlantic, the strongest Atlantic hurricane ever, the most hurricanes and the highest accumulated cyclone energy index on record. There were so many storms that we ran out of names for them. By the time Hurricane Epsilon died away in December, 28 tropical cyclones had swept through the area.

Tropical cyclones include hurricanes, typhoons and tropical depressions, and are characterized by rapid rotation, a central low-pressure center, strong winds and heavy rain.

Storm Overload

Now, writing in Science Advancesresearchers find that the 2005 season can go down as essentially the most tropical cyclone-rich year ever. Using several different models, they find that 28 tropical cyclones is very near the effective limit for storms in the North Atlantic in one season, and is unlikely to be topped under current climate conditions.

If there was a dial for the North Atlantic, that year it would have been set to “Max Hurricane”.

Researchers led by two scientists from Australia’s Climate Science Center used data on storms in the North Atlantic dating back to 1851. That allowed them to capture storms that meteorologists may have missed before the era of satellite surveillance. They plugged this data into two separate models of storm formation to generate what’s called genesis potential indices (GPI’s), estimates of how large-scale climate conditions play into the formation of tropical cyclones.

They ran the two models for long periods of time — 1,000 years for one, and 5,000 years for another — to see what the upper limit on the number of storms in a single season might be. There was just a 3.5 percent chance that any given year would exceed the 2005 total of 28 storms, and even then, it did not exceed that number by much.

So, while a given year could be theoretically more stormy than 2005, it offers a good practical limit for what we might expect. That being said, predicting how storm-filled any given year might be using their models is difficult because there are many variables that change randomly (or, at least, are beyond our abilities to predict) from year to year.

Their work offers some guidance to disaster-relief agencies and organizations when it comes to assessing the worst they may need to prepare for, the researchers say. And they don’t need to prepare for any more storms than we saw in 2005, in other words.

The researchers models couldn’t say anything about how fierce the storms of the near future might be though, nor could they predict where they might fall, and thus, where preparations should be made. There’s been an increasing upward trend in the severity of hurricanes, and that only seems poised to continue. In addition, we could see more storms that cross the line from tropical depression to hurricane, meaning that hurricane numbers could tick upward in the future.

While we may have already experienced the max amount of tropical cyclones we’ll ever get in a season, that doesn’t mean they can’t get stronger.

CATEGORIZED UNDER: Environment, top posts
  • OWilson

    Looking at the actual study, the data goes back to 1860.

    Today we have satellite technology that is observing and recording in minute detail the Earth’s constantly changing winds, weather, and cloud patterns.

    Aside from NOAA’s revisions to it’s parameters (lowered wind speed) and storm naming conventions over time, even a disturbance that briefly hits the parameters of a “tropical storm” or “hurricane” over an uninhabited area. and dissipates just as quickly, it is recorded as a “hit”.

    As Spacedotcom reports, NOAA’s “new GOES-East satellite launched in 2016, has provided (high definition) views of developing weather in unprecedented detail. The satellite will be able to scan each spot below it every 5 minutes, or every 1 minute to 30 seconds on special focus areas — in the latter case, for developing weather events”.

    Until the satellite age these often temporary disturbances would go unobserved and unreported, except by unfortunate seafarers who actually encountered one.

    So until we have a record of consistent observation using the same definitions, we should be careful of extrapolating from inconsistent data.

    Else we find ourselves in the situation we have today, where NOAA’s and CSU forecasts of “above average” storm activity, where all the “models” were in place, for this to happen, is quietly revised to “near normal”, and a “less active” season. But these revised forecasts are made in August, halfway through the Hurricane Season! :)

    But that will go down nonetheless as a successful forecast (by their standards), so its (intentionally?) difficult to quantify their forecasting record :)

    No doubt we will get there in time, but we are not there yet! In the meantime predicting anything more than an average hurricane season is just speculation!

    That’s why climatology is considered a “soft” science!

  • Mike Richardson

    Considering the amount of heat humankind has trapped with our greenhouse gas emissions, it’s hardly surprising that we are approaching the theoretical limits. If anything, the estimates of global warming’s impact have been too conservative. Only the willfully ignorant and blindly partisan continue to deny that now, though they grow fewer in number each year. Unfortunately, that attrition rate may be too little, too late for the rest of us.


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