Hurricane Sandy's huge size: freak of nature or climate change?

By: Dr. Jeff Masters , 1:10 PM GMT on November 13, 2012

Hurricane Sandy was truly astounding in its size and power. At its peak size, twenty hours before landfall, Sandy had tropical storm-force winds that covered an area nearly one-fifth the area of the contiguous United States. Since detailed records of hurricane size began in 1988, only one tropical storm (Olga of 2001) has had a larger area of tropical storm-force winds, and no hurricanes has. Sandy's area of ocean with twelve-foot seas peaked at 1.4 million square miles--nearly one-half the area of the contiguous United States, or 1% of Earth's total ocean area. Most incredibly, ten hours before landfall (9:30 am EDT October 30), the total energy of Sandy's winds of tropical storm-force and higher peaked at 329 terajoules--the highest value for any Atlantic hurricane since at least 1969. This is 2.7 times higher than Katrina's peak energy, and is equivalent to five Hiroshima-sized atomic bombs. At landfall, Sandy's tropical storm-force winds spanned 943 miles of the the U.S. coast. No hurricane on record has been wider; the previous record holder was Hurricane Igor of 2010, which was 863 miles in diameter. Sandy's huge size prompted high wind warnings to be posted from Chicago to Eastern Maine, and from Michigan's Upper Peninsula to Florida's Lake Okeechobee--an area home to 120 million people. Sandy's winds simultaneously caused damage to buildings on the shores of Lake Michigan at Indiana Dunes National Lakeshore, and toppled power lines in Nova Scotia, Canada--locations 1200 miles apart!

Largest Atlantic tropical cyclones for area covered by tropical storm-force winds:

Olga, 2001: 780,000 square miles
Sandy, 2012: 560,000 square miles
Lili, 1996: 550,000 square miles
Igor, 2010: 550,000 square miles
Karl, 2004: 430,000 square miles

Figure 1. Hurricane Sandy’s winds (top), on October 28, 2012, when Sandy was a Category 1 hurricane with top winds of 75 mph (this ocean surface wind data is from a radar scatterometer on the Indian Space Research Organization’s (ISRO) Oceansat-2.) Hurricane Katrina’s winds (bottom) on August 28, 2005, when Katrina was a Category 5 hurricane with top winds of 175 mph (data taken by a radar scatterometer on NASA’s defunct QuickSCAT satellite.) In both maps, wind speeds above 65 kilometers (40 miles) per hour are yellow; above 80 kph (50 mph) are orange; and above 95 kph (60 mph) are dark red. The most noticeable difference is the extent of the strong wind fields. For Katrina, winds over 65 kilometers per hour stretched about 500 kilometers (300 miles) from edge to edge. For Sandy, winds of that intensity spanned an region of ocean three times as great--1,500 kilometers (900 miles). Katrina was able to generate a record-height storm surge over a small area of the Mississippi coast. Sandy generated a lower but highly destructive storm surge over a much larger area, due to the storm's weaker winds but much larger size. Image credit: NASA.

How did Sandy get so big?
We understand fairly well what controls the peak strength of a hurricane's winds, but have a poor understanding of why some hurricanes get large and others stay small. A number of factors probably worked together to create a "prefect storm" situation that allowed Sandy to grow so large, and we also must acknowledge that climate change could have played a role. Here are some possible reasons why Sandy grew so large:

1) Initial size of the disturbance that became Sandy was large
Sandy formed from an African tropical wave that interacted with a large area of low pressure that covered most of the Central Caribbean. Rotunno and Emanuel (1987) found that hurricanes that form from large initial tropical disturbances like Sandy did tend to end up large in size.

Figure 2. The initial disturbance that spawned Sandy, seen here on October 20, 2012, was quite large.

2) High relative humidity in Sandy's genesis region
The amount of moisture in the atmosphere may play an important role in how large a hurricane gets (Hill and Lackmann, 2009.) Sandy was spawned in the Caribbean in a region where the relative humidity was near 70%. This is the highest humidity we saw during 2012 during the formation of any Atlantic hurricane.

3) Passage over Cuba
Sandy struck Cuba as an intensifying Category 2 hurricane with 110 mph winds. While the core of the storm was over Cuba, it was cut off from the warm ocean waters surrounding Cuba. Most of Sandy's large circulation was still over the ocean, though, and the energy the storm was able to extract from the ocean went into intensifying the spiral bands over water. When Sandy's core re-emerged over water, the hurricane now had spiral bands with heavier thunderstorm activity as a result of the extra energy pumped into the outer portion of the storm during the eye's passage over land. This extra energy in the outer portions of Sandy may have enabled it to expand in size later.

4) Interaction with a trough of low pressure over the Bahamas
As Sandy passed through the Bahamas on October 25, the storm encountered strong upper-level winds associated with a trough of low pressure to the west. These winds created high wind shear that helped weaken Sandy and destroy the eyewall. However, Sandy compensated by spreading out its tropical storm-force winds over a much wider area. Between 15 and 21 UTC on October 25, Sandy's area of tropical storm-force winds increased by more than a factor of two.

5) Leveraging of the Earth's spin
As storms move towards Earth's poles, they acquire more spin, since Earth's rotation works to put more vertical spin into the atmosphere the closer one gets to the pole. This extra spin helps storms grow larger, and we commonly see hurricanes grow in size as they move northwards.

6) Interaction with a trough of low pressure at landfall
As Sandy approached landfall in New Jersey, it encountered an extratropical low pressure system to its west. This extratropical storm began pumping cold air aloft into the hurricane, which converted Sandy into an extratropical low pressure system, or "Nor'easter". The nature of extratropical storms is to have a much larger area with strong winds than a hurricane does, since extratropical storms derive their energy from the atmosphere along a frontal boundary that is typically many hundreds of miles long. Thus, as Sandy made landfall, the hurricane's strongest winds spread out over a larger area, causing damage from Indiana to Nova Scotia.

Are we likely to see more such storms in the future?
Global warming theory (Emanuel, 2005) predicts that a 2°C (3.6°F) increase in ocean temperatures should cause an increase in the peak winds of the strongest hurricanes of about about 10%. Furthermore, warmer ocean temperatures are expected to cause hurricanes to dump 20% more rain in their cores by the year 2100, according to computer modeling studies (Knutson et al., 2010). However, there has been no published work describing how hurricane size may change with warmer oceans in a future climate. We've seen an unusual number of Atlantic hurricanes with large size in recent years, but we currently have no theoretical or computer modeling simulations that can explain why this is so, or if we might see more storms like this in the future. However, we've seen significant and unprecedented changes to our atmosphere in recent decades, due to our emissions of heat-trapping gases like carbon dioxide. The laws of physics demand that the atmosphere must respond. Atmospheric circulation patterns that control extreme weather events must change, and we should expect extreme storms to change in character, frequency, and intensity as a result--and not always in the ways our computer models may predict. We have pushed our climate system to a fundamentally new, higher-energy state where more heat and moisture is available to power stronger storms, and we should be concerned about the possibility that Hurricane Sandy's freak size and power were partially due to human-caused climate change.

Emanuel, K. (2005). Increasing destructiveness of tropical cyclones over the past 30 years. Nature, 436(7051), 686-688.

Hill, Kevin A., and Gary M. Lackmann (2009), "Influence of environmental humidity on tropical cyclone size," Monthly Weather Review 137.10 (2009): 3294-3315.

Knutson, T. R., McBride, J. L., Chan, J., Emanuel, K., Holland, G., Landsea, C., ... & Sugi, M. (2010). Tropical cyclones and climate change. Nature Geoscience, 3(3), 157-163.

Rotunno, R., & Emanuel, K. A. (1987). An air–sea interaction theory for tropical cyclones. Part II: Evolutionary study using a nonhydrostatic axisymmetric numerical model. J. Atmos. Sci, 44(3), 542-561.

The Atlantic is quiet, but a Nor'easter expected next week
The Atlantic is quiet, with no threat areas to discuss. An area of low pressure is predicted to develop just north of Bermuda on Wednesday, and the GFS model predicts that this low could become a subtropical cyclone as moves north-northeastwards out to sea late in the week.

The long-range models are in increasing agreement that a Nor'easter will develop near the North Carolina coast on Sunday, then move north to northeastwards early next week. High winds, heavy rain, and coastal flooding could affect the mid-Atlantic coast and New England coasts next Monday and Tuesday due to this storm, but it appears likely that the Nor'easter will stay farther out to sea than the last Nor'easter and have less of an impact on the region devastated by Sandy. Ocean temperatures off the coast of North Carolina were cooled by about 4°F (2.2°C) due to the churning action of Hurricane Sandy's winds, but are still warm enough at 22 - 24°C to potentially allow the Nor'easter to acquire some subtropical characteristics. I doubt the storm would be able to become a named subtropical storm, but it could have an unusual amount of heavy rain if it does become partially tropical. The Nor'easter is still a long ways in the future, and there is still a lot of uncertainty on where the storm might go.

Jeff Masters

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Good Morning all,
41 degrees,P/Cloudy,76%RH,5 mph winds from the NNE,30.27"
A webcam pic from around here..

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510. etxwx
Good morning everyone. It's a chilly morning here in East Texas, possible frost tonight.

In today's insect news....
Grasshoppers that live in noisy urban environments are having to change their song, a study has found.
BBC 11.14.12
Excerpt: Researchers suggest that high levels of background noise may affect the grasshoppers' mating process. They say the insects are forced to increase the volume of the low-frequency sections of their call.

Results of the study, by scientists from the University of Bielefeld, Germany, are published in the journal Functional Ecology. The research, which shows traffic noise could upset bow-winged grasshoppers' (Chorthippus biguttulus) mating system, is the first of its kind, according to lead researcher Ulrike Lampe.

"Increased noise levels could affect grasshopper courtship in several ways," commented Ms Lampe. "It could prevent females from hearing male courtship songs properly, prevent females from recognising males of their own species, or impair females' ability to estimate how attractive a male is from his song."

More details here.
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Following yesterday's block-buster by the professional business service giant PricewaterhouseCoopers, today brings a statement in the International Energy Agency, World Energy Outlook 2012 that looks like it was written by a member of

The IEA report can be downloaded here.

The statement for those who just want the meat is:

"No more than one-third of proven reserves of fossil fuels can be consumed prior to 2050 if the world is to achieve the 2 °C goal, unless carbon capture and storage (CCS) technology is widely deployed. This finding is based on our assessment of global “carbon 16 reserves”, measured as the potential CO2 emissions from proven fossil-fuel reserves. Almost two-thirds of these carbon reserves are related to coal, 22% to oil and 15% to gas. Geographically, two-thirds are held by North America, the Middle East, China and Russia. These findings underline the importance of CCS as a key option to mitigate CO2 emissions, but its pace of deployment remains highly uncertain, with only a handful of commercial- scale projects currently in operation."

Personally, I think they are placing too much hope in CCS, sort of like a friend of mine who keeps taking about fusion.

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Sorry to be so verbose on here this morning. Is there a Jet Stream and ITCZ overlay for the Sat Animation?
Member Since: December 28, 2006 Posts: 119 Comments: 1638
hydrus, that concrete dock deck must have had serious design issues to get completely removed by a cat 1 in the first year after construction.
I guess naming your town big mouth is better than rat's mouth.
Yo' has a good point in that you don't notice sea level rise year in and year out as tide cycles and storm systems rise and fall. It is the major events bringing storm surge from into your yard, to into your house...or into the subway and tunnels,that cause you to take notice. Why would you notice two or three or four millimeters a year when the tide rises and falls thousands of times that twice a day?
Sure over 20 years it adds up, but if it isn't your house or hotel whose foundation is getting washed out during a strong new moon tide (like today) on year 19, you don't notice.
[FYI sea level rise is the climate, not climate change. The rate can be argued]
Member Since: December 28, 2006 Posts: 119 Comments: 1638
Quoting allancalderini:
Good Morning.Td 26 in the WPAC has a weird and little unusual track in that region even though it has occurred in the past.

I didn't even know there was a TD in the WPAC until you just mentioned it. It could become a tropical storm before landfall.

Member Since: March 16, 2012 Posts: 128 Comments: 7990
Quoting TropicalAnalystwx13:

IMO,NHC thinks this area near Bermuda will not develop.
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Good Morning.Td 26 in the WPAC has a weird and little unusual track in that region even though it has occurred in the past.
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501. biff4ugo
12:41 PM GMT on November 14, 2012
Why does the UV map seem to take into account Cloud Cover and Latitude but not Altitude? that seems like a major oops.
Member Since: December 28, 2006 Posts: 119 Comments: 1638
500. GeoffreyWPB
12:37 PM GMT on November 14, 2012
For West Palm Beach...

Member Since: September 10, 2007 Posts: 0 Comments: 12596
499. GeoffreyWPB
12:34 PM GMT on November 14, 2012
498. SFLWeatherman
12:32 PM GMT on November 14, 2012
6 to 10day

8 to 14day
Member Since: May 23, 2012 Posts: 0 Comments: 5179
497. TropicalAnalystwx13
12:31 PM GMT on November 14, 2012
Member Since: July 6, 2010 Posts: 128 Comments: 35274
496. PensacolaDoug
12:30 PM GMT on November 14, 2012
Quoting RussianWinter:

...Power corrupts.

And remember...."Never underestimate the power of stupid people in large groups".

I'm not sure who said that 1st, but I do agree with it.
Member Since: July 25, 2006 Posts: 2 Comments: 955
495. wxchaser97
12:29 PM GMT on November 14, 2012
Good morning everyone, it is a cold morning this morning at 22F in SE MI. I even had a light dusting of snow last morning.
Member Since: March 16, 2012 Posts: 128 Comments: 7990
494. TropicalAnalystwx13
12:23 PM GMT on November 14, 2012
Quoting TomTaylor:
thanks. TA's post had succession in it, I blame it on him.

Succession when talking about states leaving the union is completely correct. Don't let others tell you otherwise.
Member Since: July 6, 2010 Posts: 128 Comments: 35274
493. aislinnpaps
12:19 PM GMT on November 14, 2012
Ugh, got son up and new battery in smoke detector and it is still beeping. None of the others are.

Everyone have a wonderful Wednesday!
Member Since: August 22, 2009 Posts: 0 Comments: 3200
492. SFLWeatherman
12:18 PM GMT on November 14, 2012
Member Since: May 23, 2012 Posts: 0 Comments: 5179
491. MahFL
11:53 AM GMT on November 14, 2012
Drizzle here in downtown JAX.
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490. HondosGirl
11:48 AM GMT on November 14, 2012
Good morning. Looks very gloomy out this morning here in NWFL -- cool, but not cold. Despite being densly overcast, it seems much drier out today. Have a great day!
Member Since: August 20, 2011 Posts: 0 Comments: 112
489. aislinnpaps
11:15 AM GMT on November 14, 2012
Good morning/evening, all. Horrible night here, the smoke detector needs a new battery and started going off every few seconds all night long in my bedroom. Being as I lost everything in a house fire almost two years ago to the day, it really spooked me. It's too high for me to fix, so I'll get my son on a ladder later today to fix it.

A little warmer today, 40 degrees with a windchill of 36. I'll warm up the car again today before leaving for work.
Member Since: August 22, 2009 Posts: 0 Comments: 3200
488. indianrivguy
10:57 AM GMT on November 14, 2012
Top o the morning to you sir!
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487. LargoFl
10:36 AM GMT on November 14, 2012
Good Morning Folks!.........................
Member Since: August 6, 2011 Posts: 7 Comments: 64175
486. LargoFl
10:33 AM GMT on November 14, 2012
Member Since: August 6, 2011 Posts: 7 Comments: 64175
485. TomTaylor
10:19 AM GMT on November 14, 2012
Quoting drs2008:
please. Its secession not succession( to be successful)
thanks. TA's post had succession in it, I blame it on him.
Member Since: August 24, 2010 Posts: 19 Comments: 4358
484. yonzabam
9:56 AM GMT on November 14, 2012
Some of the regular contributors on here are concerned about chemical pollutants in drinking water. This article is from today's New York Times, about the pollution in tapwater delivered to southern Californian agricultural workers. It makes for disturbing reading.

Member Since: July 20, 2008 Posts: 0 Comments: 3560
483. HadesGodWyvern (Mod)
9:24 AM GMT on November 14, 2012
India Meteorological Department
Tropical Cyclone Outlook
8:30 AM IST November 14 2012

a low pressure area has formed over southeast and adjoining southwest Bay of Bengal. The system would become well marked during next 48 hours.
Member Since: May 24, 2006 Posts: 62 Comments: 54027
482. HadesGodWyvern (Mod)
7:29 AM GMT on November 14, 2012
Japan Meteorological Agency
Tropical Cyclone Advisory #5
15:00 PM JST November 14 2012

SUBJECT: Tropical Depression In South China Sea

At 6:00 AM UTC, Tropical Depression (1004 hPa) located at 8.1N 109.0E has 10 minute sustained winds of 30 knots with gusts of 45 knots. The depression is reported as moving west northwest at 6 knots.

Dvorak Intensity: T2.0

Forecast and Intensity
24 HRS: 9.0N 106.6E - 35 knots (CAT 1/Tropical Storm) South China Sea

Additional Information

Tropical Depression will move west northwestward for the next 24 hours

Tropical Depression will be upgraded to tropical storm within 24 hours

System will develop because cyclone will stay in high sea surface temperature area

Final initial Dvorak number will be 2.5 after 24 hours
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481. LostTomorrows
5:40 AM GMT on November 14, 2012
...Is that wave in the eastern Atlantic trying to make a comeback?
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480. listenerVT
5:20 AM GMT on November 14, 2012
Thanks, Dr. Masters! I'll share this with my cousin in Milton, CT who has been asking "Why??" a lot lately.
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479. hydrus
5:07 AM GMT on November 14, 2012
Quoting Slamguitar:
On an off-topic note, all temp readings now below freezing for the LP. Hot chocolate season is here!

They should sell that stuff by the gallon, not by the cup..:)
Member Since: September 27, 2007 Posts: 1 Comments: 27397
477. hydrus
5:05 AM GMT on November 14, 2012
Quoting etxwx:

Way back in 1972, a group of us hitchhiked to Antigonish, Nova Scotia to see the total eclipse of the sun. (no Lear jets were involved...)
It was truly an amazing experience. A one of things I remember was that all the shore birds came into shore like it was evening and then went back out again a little while later when the eclipse was over . I bet they were wondering what the heck was going on.

Thanks for posting the eclipse images and info, Aussie...brings back good memories.
Sounds like a really cool experience. We had a relatively brutal beating from Agnes that year. It was only cat-1, but the winds lasted almost two days and beat the tar out of all the piers and docks. This was a solid concrete pier at Boca Grande that was totally wrecked by Agnes. It was less than a year old.
Member Since: September 27, 2007 Posts: 1 Comments: 27397
476. RussianWinter
5:03 AM GMT on November 14, 2012
Quoting yoboi:

true but why did so many die during sandy here????

Unfamiliarity with danger.
Failure to listen to government warnings.
More over, post-storm accidents.
Can't save everyone, so try to save as many as you can.

...Remember the fact that meteorological history doesn't go back that long...
...On the American continents.
Member Since: August 21, 2011 Posts: 0 Comments: 666
475. uncwhurricane85
4:55 AM GMT on November 14, 2012
Quoting yoboi:

i am talking about weather read back.....and chill

weather is weather in any book...but i gotcha
Member Since: August 4, 2010 Posts: 0 Comments: 583
472. RussianWinter
4:51 AM GMT on November 14, 2012
Quoting yoboi:

another example look at isaac they rebuilt the levees in new orleans after katrina protected them but caused cat 4 flooding south of new orleans....

The good thing is, a good amount of people were able to evacuate with a lower death count. Sure, property damage is high, but at least it's not people.
Member Since: August 21, 2011 Posts: 0 Comments: 666
471. uncwhurricane85
4:44 AM GMT on November 14, 2012
Quoting yoboi:

how can you prove the book of revelations is wrong please steer me to a book or study that debunks it...

just stop! nobody can prove the BIBLE is right or wrong period! let alone a part of the bible! get over it, lets talk about the weather!
Member Since: August 4, 2010 Posts: 0 Comments: 583
469. Slamguitar
4:36 AM GMT on November 14, 2012
On an off-topic note, all temp readings now below freezing for the LP. Hot chocolate season is here!

Member Since: July 2, 2011 Posts: 0 Comments: 1185
466. RussianWinter
4:17 AM GMT on November 14, 2012
Quoting yoboi:

not really we all are corrupt sorry can't use the word sinned....because i will get bashed....i just go by we should not throw rocks in a glass house...

We all have selfish desires. But that doesn't mean we can't help other people, right?
Member Since: August 21, 2011 Posts: 0 Comments: 666
465. RussianWinter
4:13 AM GMT on November 14, 2012
Quoting yoboi:

what i am saying is i can't say the sea rise cliff will not happen in 2100 if that holds true what is the plan to save cities and people????

Rome wasn't built in a day...

...But Europe has recovered nicely from WW2.
...And so will Manhattan.
Member Since: August 21, 2011 Posts: 0 Comments: 666
463. RussianWinter
4:12 AM GMT on November 14, 2012
Quoting yoboi:

if the sea rise cliff is in 2100 what is the plan to save life???

Do you think water levels will just rise in a snap in New Year 100?

No, they are going to rise by tiny millimeters in a slow amount of time?

There will be some rough times handling all the... displacement of people, but climate change sea rises is not a storm surge.
Member Since: August 21, 2011 Posts: 0 Comments: 666
461. RussianWinter
4:08 AM GMT on November 14, 2012
Quoting yoboi:

good idea knowledge is power...

...Power corrupts.
Member Since: August 21, 2011 Posts: 0 Comments: 666

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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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