Hurricane Sandy a 1-in-700-Year Event Says NASA Study

Rebecka writes "Hurricane Sandy, which pelted multiple states in Oct. and created billions of dollars in damage, was a freak occurrence and not an indication of future weather patterns, according to NASA's Goddard Institute for Space Studies via LiveScience. The study (abstract), which calculated a statistical analysis of the storm's trajectory and monitored climate changes' influences on hurricane tracks, claims that the tropical storm was merely a 1-in-700-year event. 'The particular shape of Sandy's trajectory is very peculiar, and that's very rare, on the order of once every 700 years,' said senior scientist at NASA and study co-author, Timothy Hall. According to Hall, the extreme flooding associated with the storm was also due to the storm's trajectory which was described as being 'near perpendicular.' The storm's unusual track was found to have been caused by a high tides associated with a full moon and high pressure that forced the storm to move off the coast of the Western North Atlantic."

Comments

Re:Once in a Hundred-Year storm...

[MightyYar]

You are conflating what NASA said with something your local weatherman may have said.

Re:The problem with Probability...

[vux984]

False. 0.5^1000 == 0.5^1000 no matter how many trials there are

Your right of course. But he's saying the longer you flip a coin, the more likely you will see an occurrence of 1000 heads in a row, and this is true.

Lets look at a smaller set 2 heads in a row:

The odds when flipping a coin twice is 0.5^2. or 1 in 4.
The odds when flipping a coin twice more is again 1 in 4.
repeat ad nauseum, which is your argument.

His observation is that if you flip it 3 times, the odds of two heads coming up in a row increases, and it does. It's now 3 in 8 which is greater than 1 in 4. If you flip it 4 times... its up to 8 in 16 (or 50%), 5 times, and your odds get to 19/32 which is almost 60%, 6 times 51/64 (almost 80%).

That doesn't change the odds of a superstorm happening next year, or next week. Its still a 1 in 700 year probability. But the thing about statistically unlikely things is not only that they can happen, but that they DO happen, and over a long enough period unlikely things are nearly inevitable.

The NASA paper bears no resemblance to the summary

[petaflop]

The NASA paper does not say that Sandy was not influenced by climate change. What they actually calculate is that Sandy-like hurricanes occur once in 700 years under pre-industrial conditions. Here is one of many relevant quotes:

The fact that our calculations show Sandy’s track to be so rare under long-term average climate conditions lends support to a climate-change influence. On the other hand, the most recent climate model simulations project reductions in blocking frequency in a warmer climate [Dunn-Sigouin and Son, 2012]. Global high-resolution models suggest that tropical cyclone frequency will decrease globally, while mean intensity will increase. There is growing consensus that the most intense events will increase in frequency, but there is high uncertainty, especially in individual basins [Knutson et al., 2010]. On the other hand, further sea level rise is almost certain, with a meter or more expected in the next century [Nicholls and Cazenave, 2010]. This will exacerbate TC-induced flooding even if the storms themselves do not change.

Someone should have RTFA.