Why did Hurricane Sandy take such an unusual track into New Jersey?

By: Dr. Jeff Masters , 4:33 PM GMT on October 31, 2012

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We're used to seeing hurricane-battered beaches and flooded cities in Florida, North Carolina, and the Gulf Coast. But to see these images from the Jersey Shore and New York City in the wake of Hurricane Sandy is a shocking experience. New Jersey only rarely gets hit by hurricanes because it lies in a portion of the coast that doesn't stick out much, and is too far north. How did this happen? How was a hurricane able to move from southeast to northwest at landfall, so far north, and so late in hurricane season? We expect hurricanes to move from east to west in the tropics, where the prevailing trade winds blow that direction. But the prevailing wind direction reverses at mid-latitudes, flowing predominately west-to-east, due to the spin of the Earth. Hurricanes that penetrate to about Florida's latitude usually get caught up in these westerly winds, and are whisked northeastwards, out to sea. However, the jet stream, that powerful band of upper-atmosphere west-to-east flowing air, has many dips and bulges. These troughs of low pressure and ridges of high pressure allow winds at mid-latitudes to flow more to the north or to the south. Every so often, a trough in the jet stream bends back on itself when encountering a ridge of high pressure stuck in place ahead of it. These "negatively tilted" troughs have winds that flow from southeast to northwest. It is this sort of negatively tilted trough that sucked in Sandy and allowed the hurricane to take such an unusual path into New Jersey.


Figure 1. Inlet section of Atlantic City, N.J., after Hurricane Sandy. Image credit: 6 ABC Action News.

The 1903 Vagabond Hurricane
The only other hurricane to hit New Jersey since 1851 besides Sandy was the 1903 Category 1 Vagabond Hurricane. According to Wikipedia, the Vagabond Hurricane caused heavy damage along the New Jersey coast ($180 million in 2006 dollars.) The hurricane killed 57 people, and endangered the life of President Theodore Roosevelt, who was sailing on a yacht near Long Island, NY, when the hurricane hit. However, the Vagabond Hurricane hit in September, when the jet stream is typically weaker and farther to the north. It is quite extraordinary that Sandy was able to hit New Jersey in late October, when the jet stream is typically stronger and farther south, making recurvature to the northeast much more likely than in September.


Figure 2. The path of the 1903 Vagabond Hurricane, the only other hurricane to hit New Jersey since 1851.

The blocking ridge that steered Sandy into New Jersey
A strong ridge of high pressure parked itself over Greenland beginning on October 20, creating a "blocking ridge" that prevented the normal west-to-east flow of winds over Eastern North America. Think of the blocking ridge like a big truck parked over Greenland. Storms approaching from the west (like the fall low pressure system that moved across the U.S. from California to Pennsylvania last week) or from the south (Hurricane Sandy) were blocked from heading to the northeast. Caught in the equivalent of an atmospheric traffic jam, the two storms collided over the Northeast U.S., combined into one, and are now waiting for the truck parked over Greenland to move. The strength of the blocking ridge, as measured by the strength of the North Atlantic Oscillation (NAO), was quite high--about two standard deviations from average, something that occurs approximately 5% of the time. When the NAO is in a strong negative phase, we tend to have blocking ridges over Greenland.


Figure 3. Jet stream winds at a pressure of 300 mb on October 29, 2012, as Hurricane Sandy approached the coast of New Jersey. Note that the wind direction over New Jersey (black arrows) was from the southeast, due to a negatively tilted trough of low pressure over the Eastern U.S. caused by a strong blocking ridge of high pressure over Greenland. Image credit: NOAA/ESRL.

Arctic sea ice loss can cause blocking ridges
Blocking ridges occur naturally, but are uncommon over Greenland this time of year. According to NOAA's Climate Prediction Center, blocking near the longitude of Greenland (50°W) only occurs about 2% of the time in the fall. These odds rise to about 6% in winter and spring. As I discussed in an April post, Arctic sea ice loss tied to unusual jet stream patterns, three studies published in the past year have found that the jet stream has been getting stuck in unusually strong blocking patterns in recent years. These studies found that the recent record decline in Arctic sea ice could be responsible, since this heats up the pole, altering the Equator-to-pole temperature difference, forcing the jet stream to slow down, meander, and get stuck in large loops. The 2012 Arctic sea ice melt season was extreme, with sea ice extent hitting a record lows. Could sea ice loss have contributed to the blocking ridge that steered Sandy into New Jersey? It is possible, but we will need to much more research on the subject before we make such a link, as the studies of sea ice loss on jet stream patterns are so new. The author of one of the new studies, Dr. Jennifer Francis of Rutgers, had this say in a recent post by Andy Revkin in his Dot Earth blog: "While it’s impossible to say how this scenario might have unfolded if sea-ice had been as extensive as it was in the 1980s, the situation at hand is completely consistent with what I’d expect to see happen more often as a result of unabated warming and especially the amplification of that warming in the Arctic."

Jeff Masters

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American Red Cross ‏@RedCross

> 9,000 people spent Tuesday night in 171 #RedCross shelters in 13 states. You can help: http://www.redcross.org/charitable-donations …
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Quoting ncstorm:
I wonder if people in NY, MD, VA, PA, DC, NC, CT and NJ who have lost property and family members and currently without power care about the Artic Sea Ice?
If not before, then they probably will. CNN had an article yesterday about the general GW topic:

We should not be surprised. That's the view of many climate scientists as they survey the destruction wrought by the superstorm that ravaged the Northeast this week. The melting of Arctic ice, rising sea levels, the warming atmosphere and changes to weather patterns are a potent combination likely to produce storms and tidal surges of unprecedented intensity, according to many experts.

http://www.cnn.com/2012/10/31/us/sandy-climate-ch ange/index.html?iref=allsearch

Maybe these "super-storms" are indeed coming!...

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Thanks Doc!
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Quoting ncstorm:
I wonder if people in NY, MD, VA, PA, DC, NC, CT and NJ who have lost property and family members and currently without power care about the Artic Sea Ice?


They probably care a lot about any and all factors that may lead to more storms in their region. More so than ever.
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19/10/1 busy season...

Only significant hurricane was north of 25N, right around 28/30N. 2 dozen minimal intensity. wtf

Conditions are extremely hostile just about basin wide.
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I wonder if people in NY, MD, VA, PA, DC, NC, CT and NJ who have lost property and family members and currently without power care about the Artic Sea Ice?
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Thanks Dr. M!
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Thank you Dr. Masters
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Thanks Dr. Masters.
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Repost from last blog.
948. hydrus 4:29 PM GMT on October 31, 2012 1

Quoting MrMixon:
All of you people saying that the lottery is a sound financial investment are wrong.

All of you people saying puppies aren't cute are totally wrong too.

All of you people saying water isn't wet are also wrong.



OK, see how this works? I can come on here and say "all you people saying X are wrong" and I can insert whatever silly thing I want to insert for X even if nobody has actually said it. But, I think most of the adults in the room realize that doing this is intellectually dishonest.

If you're going to claim that "All the people saying X are wrong" your argument will carry more weight if you include actual quotes of people saying X.

Also, I must say the blog has disappointed me the past couple days. I'm used to the usual AGW arguments, but given the destructiveness of this storm I fully expected to see this comment section packed with current information, storm damage reports, photos, videos, radar loops, etc. Sure, some folks have been posting that kind of info, and of course I always expect a stray AGW comment here and there, but I NEVER would've predicted that such a large portion of the comments would be devoted to these arguments. So much for disasters bringing us closer together...


(Some of the pictures coming out of the Northeast look more like post-war images than post-hurricane...)

..( me :)..Good post. With massive devastating storms like Sandy and other similar storms affecting the globe, it was almost inevitable the GW debate would surface here on the good Dr,s blog. I posted my feelings on the subject simply to express my thoughts on posts I have read in the past that did not seem logical. We lost a house to the 1992 December Nor,Easter on the New Jersey Coast, and in no way would diminish the seriousness of situation that millions of folks are experiencing. I now put the GW topic to rest until a later date.
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Thanks Doc.
Member Since: September 27, 2007 Posts: 1 Comments: 22312
India Meteorological Department
Tropical Cyclone Advisory #21
CYCLONIC STORM NILAM (BOB02-2012)
17:30 PM IST October 31 2012
=========================================

Cyclonic Storm NILAM Crossed North Tamilnadu Coast

At 12:00 PM UTC, Cyclonic Strom Nilam moved north northwestwards and crossed northern Tamil Nadu coast near 12.6N 80.2E, south of Chennai, India between 1030 and 1130 AM UTC. The cyclone now lays near 12.7N 79.8E or about 50 km south southwest of Chennai, India. The system is likely to move northwestward and weaken into a deep depression during the next 6 hours.

According to satellite imagery, associated broken to solid intense to very intense convective clouds are observed north Tamil Nadu, adjoining Rayalseema, adjoining Bay of Bengal between 9.0N to 15.0N west of 82.0E.

The sustained winds near the center along and off northern Tamil Nadu, Puducherry, and adjoining southern Andhra Pradesh coast will continue to be about 35-40 knots. during the next 6 hours and decrease thereafter. Sea conditions is very rough to high along the coast for the next 5 hours before decreasing.

Forecast and Intensity
======================
6 HRS: 13.5N 79.0E - 30 knots (Deep Depression)
12 HRS: 14.5N 78.0E - 25 knots (Depression)
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Thank you Dr. Masters
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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