30 Oct 2012

What made Hurricane Sandy’s impact so great?

A week after hitting the Caribbean, Hurricane Sandy made landfall along the east coast of the US on Monday evening as a powerful storm.

Worst fears have been realised, with 16 people killed, millions of homes without power, and road, rail and airline networks paralysed.

Only last year, New York City and other parts of the eastern US were hit by Hurricane Irene, which left a trail of damage and disruption, estimated by NOAA to have cost $19bn.

So what has made Hurricane Sandy’s impact so great?

Size

The size of Hurricane Sandy was truly phenomenal – something that can only be fully appreciated when looking at the storm on a satellite picture.

Prior to making landfall, hurricane-force winds (sustained speed of 74mph and above) and tropical storm-force winds (sustained speed of 39-73mph) extended 175 miles and 485 miles from the centre of the storm respectively.

According to NOAA, in a typical large hurricane, tropical storm-force winds would only reach out 300 miles from a storm’s centre.

To put this into context, if the centre of hurricane Sandy was placed over Paris, the tropical-storm force winds would affect much of western Europe – as shown by the green circle on the map below.

Track

Sandy’s track has been crucial in terms of the impact that it has had. Normally, hurricanes that move along the east coast of the US are steered out across the Atlantic Ocean by the west to east movement of the jet stream.

However, on this occasion, the jet stream was taking a more north to south track, having less of a steering effect on Sandy.

In addition, there was a big area of high pressure to the north east of the US which effectively blocked Sandy from moving out into the Atlantic. As a result, the storm was forced to take a left turn, slamming into the east coast.

Not only is this an unusual route for a hurricane to take, it is a route that put around 60 million people in its path.

Storm surge and high tide

As the storm made landfall, there was a major storm surge along coastal areas on its northern side caused by onshore hurricane-force winds pushing water onto the coastline.

Also, with a full moon, high tides were occurring, which only added to the water levels along the shore.

These factors combined to cause major coastal flooding – especially for low-lying areas. Battery Park, New York City had storm surges reaching a record-breaking 14ft, sending torrents of water into lower Manhattan.

Damaging winds

Hurricane-force winds lashed the coastline from New Jersey to Massachusetts where gusts of up to 90mph were experienced.

This strength of wind came at a time of year when some trees are still in leaf. Leaves on trees act as sails and make them more prone to being blown down, as does heavy rain, softening the ground that holds their roots.

Urban areas are even more prone to damage from strong winds because the layout of buildings can cause the wind to funnel between them, giving the wind an extra kick.

Very tall buildings like skyscrapers would have experienced even stronger winds than those measured at ground level. This is because the wind blows even faster just a few hundred metres above the ground due to it experiencing less friction and flowing more freely.

It is probable that the top of the Empire State building experienced wind gusts in the range of 120mph, if not a little more.

Climate change?

There’s no doubt that some will debate on whether climate change can be said to have had an influence on hurricane Sandy. However, it’s not wise or reasonable to use a single weather event when considering a changing climate.

On the other hand, future predictions of a warmer world would allow the atmosphere to hold more moisture, which could equate to more significant rainfall events taking place.

Also, warmer ocean waters could potentially give hurricanes a bigger playground in which to roam, as this is where they draw their energy from in order to thrive.

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21 reader comments

  1. Tom says:

    “There’s no doubt that some will debate on whether climate change can be said to have had an influence on hurricane Sandy. However, it’s not wise or reasonable to use a single weather event when considering a changing climate.”

    Mr. Dutton…the only debate about climate change have an influence on hurricanes like Sandy come from those who ignore science, ignore facts, and perpetually keep their heads in the sand so they don’t have to face reality.

    How many single catastrophic weather events would it take for you to “consider a changing climate” caused by human-generated greenhouse gases and continual global pollution?

    The problem with journalism like yours is that it keeps diverting people’s attention from the truth. Your article starts off very strong. But your summary sucks…and doesn’t show any journalistic strength.

    1. Liam Dutton says:

      Tom,

      Thanks for your message, although I think that you’ve misunderstood my point. If you read it again, it’s making the point that Sandy would need to be considered amongst a range of storms in order to make any conclusions representative.

      When it comes to science or anything else being studied to evaluate a hypothesis, more than one case study would be examined to make it robust.

    2. Aimee says:

      Although this is a valid point, its not a case of ignoring global warming. We have had many similar climate events in the past and although many species get wiped out afterwards the biodiversity continues to climb higher than before. This suggests that climate change is a normal pattern in the long term life of our planet and trying to do anything to stop it is futile. The best we can do is learn how to handle such events like issuing warnings, evacuation orders and finding ways to cope in harsh climate conditions.Looking at how many people would have been killed in a similar event 100 years ago shows that we are very aware of our climate and are making rapid advances in our methods of coping with it. On the other hand, how many people get killed by motor vehicles every year compared to those killed by hurricanes still shows where the problems in human society lay. Basically, not with mother nature.

    3. Baran Karakus says:

      Tom, the idea of humans contributing to global warming is still nothing but a theory. It is not certain. Let us look at the facts…

      The oceans contain 37,400 billion tons (GT) of suspended carbon, land biomass has 2000-3000 GT. The atmosphere contains 720 billion tons of CO2 and humans contribute only 6 GT additional load on this balance. The oceans, land and atmosphere exchange CO2 continuously so the additional load by humans is incredibly small.

      Now, even though our contribution may pale into insignificance compared to CO2 released naturally, it IS a possibility for our contribution to upset the balance of CO2 being naturally released and naturally absorbed. These 6 billion tons of extra CO2 are, for a fact, NOT being FULLY absorbed, thus leaving us with a few tons of CO2 floating in the atmosphere.

      Now, you might be thinking, so what am I getting at? Well, yes, there IS that man-made carbon dioxide building up in the atmosphere every year. BUT, and this is a big BUT, it’s not even for certain, just like how the idea of ‘global warming’ is not certain, that CO2 ACTUALLY causes global warming on the scale for our tiny contribution to cause climate change. For example, water vapour, for a start, is far more influential on world temperatures than CO2 levels.

    4. EssexGurrl says:

      I agree, why are people still wondering about climate change? The overwhelming opinion of peer-reviewed experts on climate change is agreed that climate change is happening and it is caused by humans.
      What I want to know is when will those affected start to sue climate change deniers, especially the oil companies, for damages. They are responsible, alongside the media who think the general public are gullible. We are not.

  2. David Higgins says:

    ‘it’s not wise or reasonable to use a single weather event when considering a changing climate’

    It’s even less wise to think climate change is selective switching on and of between individual weather events. It effects every weather event with greenhouse gasses emitted by us now part of the climate.

  3. Julia says:

    Great piece. Puts the storm into context for Europeans and explains why the impact was so high. Nice to see proper knowledge sharing rather than sound bites are still available from the BBC.

  4. geetasoman says:

    Man proposes and God disposes!concret jungle.the high risers buildings are giving extra force to the hurricanes.the weather patern is rap.idly changing where all the new technology is failing .we will have to look for the old, conventional ways of merging with the nature, the five elements are the supreme power and we must accept and respect them.

  5. Carl Boniface says:

    Liam thank you for your informative report that shed light on Hurricane Sandy, the size and impact it has created, and basically well founded facts that give the majority of ordinary people. like me, an idea of the scale of this event. Glad to know your report is aimed at us. Perhaps it is not scientifically accurate, but then so what, it drew a very good picture. Thanks Liam. Nice job!

  6. Christina Gross says:

    CORRECTION

    I can see that there are no scientists commenting on this article as one of them would have spotted the error ‘also, with a new moon, high tides . . .’

    There was a ‘full moon’ during the onshore approach which caused the high tides.

    Do your research, then write.

    1. Liam Dutton says:

      Well spotted Christina. Now corrected!

  7. Parm says:

    may god bless New York

  8. D Brown says:

    There are those who consider that the world actually stopped getting warmer a decade ago so. As Liam writes, one must look at a range of events to suggest that global warming alone is to blame.
    The earth goes through cycles – there was intense cold in the UK during the 1600s and we have been coming out of a cold spell since the end of the 1950s. Yes, there has definitely been an upsurge in physical phenomena recently – not one but several of the worst recorded storms in the UK have occurred in the past 20 years or so, the four of the ten worst earthquakes on record have occurred recently, the list is endless.

    One can look at the present sunspot cycle and ask if that has some bearing on the question. I don’t know.

    There has been talk of the end of the present Mayan epoch; American scientists have discovered that at the end of the last one (several thousand years ago) their location was hit by a very sudden mini ice-age. Who understands that? I cannot imagine it was the emissions of camp fires!

    For all our scientific discoveries we are still at the dawn of learning, tentatively exploring hypotheses. Perhaps the current century will see a definitive understanding of our planet; then and only then can we definitively answer yes or no to the global warming question but we cannot do so now.

    What we can do now is to use our current knowledge to control the emission of those gases which seem to contribute to making a warming blanket in the upper atmosphere, perhaps to try to contain and even use the methane being given off by the tundra as permafrost melts, reduce poisonous emissions from factories and other makeshift controls.

    As for the problems faced by the US eastern seaboard, one of the problems is that major urban centres are so close to the sea and their infrastructure is so susceptible to weather problems. As others have written, the far east experiences far worse typhoons regularly and are prepared. Is New York prepared for the western slope of Grand Canaria slipping into the sea? Perhaps they should make real contingency plans

    1. ashley haworth-roberts says:

      It was Liam’s blog post of Friday, reporting on how the hurricane was expected by the forecasters to make a sharp left turn and hit New Jersey or thereabouts (I was assuming till then that the storm would stay offshore and perhaps just produce snow on the east coast), which first alerted me to the seriousness of the situation.

      On Saturday evening I started a thread at the BBC Points of View message board commenting on how BBC TV News were already referring – understandably – to a ‘superstorm’ (I attached four links including Friday’s blog). However, as is sadly predictable, I was censored by the moderators for ‘discussing news and current affairs’.

      There has been talk today about how New York City seems to require something similar to the Thames Barrier.

  9. David Higgins says:

    D Brown, these issues have been sorted out. Sunspot activity doesnt fit with the present warming. The only reasonable explanation is that we’re having an impact. Global warming has moved beyond hypothesis, its a theory and has a huge amount of corroborating evidence.

    1. David Higgins says:

      amazing how some people manage to dislike the evidence!

  10. René De Beaumarchais says:

    Now God will bless New York after rampaging it?

    Yeah, nice going “God”.

  11. D Brown says:

    David Higgins; it’s a matter of semantics. On the eastern side of the pond a theory is an idea with some evidence. A hypothesis is a fact proven by evidence until someone disproves it. For example Einstein’s Theory of Relativity seems to be hypothesis though some are questioning whether it is totally correct. A “certain fact” doesn’t exist in science; remember the Pope versus Galileo and Pope versus Copernicus.

    René De Beaumarchais ; it is a demonstration of a law “The Universe Doesn’t Care”. A human should and would be expected to apologise and refrain from a repetition but the Universe could do the same thing again next week and not care about the result – remember New Orleans.

  12. D Brown says:

    Apologies. I should have pointed out that the law “The Universe Doesn’t Care” was put forward by Lazlo Zalezac who, I assume, has the copyright.

  13. David Higgins says:

    It doesnt matter which side of the pond youre on in scientific terms its the other way round to have you have it. A hypothesis is an idea to be tested a theory is a tested hypothesis with a hefty weight of evidence behind it. A theory is a strong statement with validity borne from testing/experiments.

  14. Clara says:

    s grain consumption increased by 36,280,000 tonnes (40 million tons).
    Although everyone thought that their city or world would cease to exist,
    that was not the actuality. See how much of this change is attributed to greenhouse gases,
    albedo (i.

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