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The Meteorological Reasons Why There Have Been So Many Hurricanes This Year

September 19, 2017

By Paul Homewood

While Hurricane Maria continues this year’s run of hurricanes, it is worth reading this Telegraph article from Sep 8th. It certainly makes a refreshing change from the wearying drivel written by Jillian Ambrose and co:

 

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The destruction left by hurricanes Irma and Harvey has left many wondering why this year has been particularly bad for disastrous weather.

Harvey pummeled Texas, while Irma has been barrelling through the Carribbean and Bahamas, hurtling towards Florida.

Many thousands of homes have been destroyed and lives have been lost after the worst hurricanes seen for some years came in from the Atlantic Ocean.

The US expects hurricanes – they have a season of them every year – but not of this magnitude.

So why is it so bad? And can we expect more in the future? We asked scientists and other experts to explain.

 

What is causing these large hurricanes?

Julian Heming, the Met Office’s tropical prediction scientist, told The Telegraph about the reasons Irma is such a large hurricane.

"Irma is a powerful hurricane because all the characteristics required to produce an intense hurricane in the Atlantic are coinciding:

  • Sea surface temperatures under Irma are 1 to 1.5°C higher than the average for this time of year providing abundant moisture and warmth.
  • The wind shear (change in wind with height) is low, meaning air can flow in up and out of the hurricane very efficiently, thus promoting intensification.
  • There are no drying influences at present, such as pockets of Saharan dust which sometimes drift out over the Atlantic.
  • Irma is moving fast enough to prevent cool water up-welled under the hurricane from having any impact on the continued feed of warm, moist air into the hurricane.
  • Up until now there has been no interaction with large land masses that might disrupt intensification due to cutting off the moisture supply."

The Met Office said that this is not totally unexpected and we have seen hurricanes of this magnitude in the past.

Mr Heming said: "It is worth pointing out that it is the peak of the hurricane season, so having hurricanes in this region now is not unexpected.

"Having three simultaneous hurricanes in the Atlantic region does not happen every year, but has been recorded several times before in the last 50 years: 1967, 1980, 1995, 1998, 2010.

"The North Atlantic hurricane season runs from June-November, with peak activity during August-October. During peak season around 96% of all Atlantic major hurricanes (categories 3, 4 and 5 on the Saffir-Simpson Hurricane wind scale) occur."

http://www.telegraph.co.uk/news/2017/09/08/hurricane-irma-many-hurricanes-will-future-asked-experts/

 

Unfortunately they then go on to spoilt it quoting the usual crooks.

They might instead have quoted some of the ample evidence that hurricanes are not becoming bigger or more powerful, despite the theories.

For instance, NOAA’s own data from their Hurricane Research Division:

 

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Atlantic basin cyclone intensity by Accumulated cyclone energy, timeseries 1895-2014

http://www.aoml.noaa.gov/hrd/tcfaq/E11.html

 

Contrary to popular myth, the season with the highest ACE was not 2005, but 1933.

And as NOAA’s Chris Landsea explains, data prior to 1966 almost certainly underestimates ACE.

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12 Comments
  1. September 19, 2017 3:57 pm

    Reblogged this on Climate Collections.

  2. September 19, 2017 4:14 pm

    Trends in tropical cyclone formation and intensification can be studied only on globally averaged data for all six basins. Also a decadal or longer time scale is needed because of extreme variability at an annual time scale particularly when the geographic span is limited to a single basin (Tom Knutson,”Tropical cyclones and climate change”. Nature Geoscience, 3.3 (2010): 157-163).

    The other problem in tropical cyclone studies is that a significant bias is introduced into the time series because of changes in data collection activity, methods, and technology over the years produces a trend of its own that must be separated from natural variability and climate change effects (Landsea, 2007) (Landsea, 2010). A high level of tropical cyclone activity in a single basin in a single year does not contain information that can be generalized or understood in a climate change context.

    The other more damning issue is that the connection between AGW and tropical cyclone formation and intensification trends is SST. The theory is that emissions cause SST to rise and that in turn changes tropical cyclone activity in excess of natural variability. But alas, we have no evidence to relate the rate of warming in SST to emissions.

    So the anthropogenic cause of changes in tropical cyclone formation and intensification trends cannot be established. Please see

    https://ssrn.com/abstract=3033001

    • HotScot permalink
      September 19, 2017 10:43 pm

      I enjoy reading your informed opinions chaamjamal.

      I’m not a scientist. Your explanations are clear and help me understand climate issues.

      Thank you.

  3. September 19, 2017 4:52 pm

    Reblogged this on WeatherAction News.

  4. September 19, 2017 9:50 pm

    It must be getting ever harder to keep people interested in global-not-much-if-any-warming.

    Frothing about hurricanes will have to do for a few weeks, then think of something else to whine about.

    • nigel permalink
      September 20, 2017 6:29 am

      People WILL get bored. It is like a pop song sung by a pretty girl. At first you think it is wonderful, and you listen to it all the time. Then you realize one day that it is too familiar, and it is kind of annoying. And the girl does not look so good when photographed falling out of a night-club at two in the morning.

  5. David Bishop permalink
    September 20, 2017 5:36 am

    Paul
    I can’t see how to send you a message outwith comments, so please excuse me if I drop this OT item here:
    https://capx.co/is-the-world-is-warming-to-clean-coal/?omhide=true&utm_source=CapX+briefing&utm_campaign=77398fd32c-EMAIL_CAMPAIGN_2017_07_17&utm_medium=email&utm_term=0_b5017135a0-77398fd32c-241821869
    Apart from a mention of carbon capture, it well describes the reasons for the huge increase in coal-powered generation in emerging countries.
    Key quote: As (Indian) minister for power Piyush Goyal put it: “Every country needs a baseload. I cannot tell my country, ‘guys, it’s 6pm in the evening, shut everything down because the solar has gone off’.”

    • bea permalink
      September 20, 2017 6:07 am

      Good for Goyal! Sometimes you do not need complicated science; just common-sense – and an absence of fanaticism!

  6. Athelstan permalink
    September 20, 2017 7:05 am

    On Monday it inflicted substantial damage on Dominica and the first aerial images of the island have emerged.

    The storm briefly weakened to a four but is now again packing top sustained winds of 280km/h (175mph).

    “packing” ?

    Um, Sky tell us this morning that ‘Maria’ is gusting at 130 mph, BBC weather Scot’s lass informed us this morning that ‘Maria’ is a Cat 5 – it must be coz winds gusting at + 157 mph, while on Radio 5 they told us that, “wind speed” estimated at 127 mph are they in a fugue of confusion and guesswork – no don’t answer that.

    An objective observer might posit:

    a) they getting their knickers tied in ‘knots’ and twisting out by miles?

    b) Al beeb, it seems that, they do fix, focus on the misery of these islanders stuck in the path of the new ‘big wind’?

    c) Are the bbc and their mates in the Wet office just a bunch rubber necking ghouls and by rather unsubtle method, actually implicating “more evidence” of man made catastrophe?

  7. avro607 permalink
    September 20, 2017 10:56 am

    Just seen the BBC interview a Professor of atmospheric physics who apparently believes that the warming air due to climate change,is the cause of warmer oceans,and thus more severe hurricanes.I felt ambarassed for the professor.

    • Athelstan permalink
      September 20, 2017 11:08 am

      “A professor” ‘air warming water’………………..ffs and to what did he also profess – enfeeblement on the grounds of insanity?

      • Gerry, England permalink
        September 20, 2017 12:52 pm

        He must have missed the comment from Dr Judith Curry that the sea temperature was low for the formation of a strong storm.

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