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Did Climate Change Have A Role in Hurricane Sandy’s Unusual Track Into New Jersey?

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"Did Climate Change Have A Role in Hurricane Sandy’s Unusual Track Into New Jersey?"

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

by Jeff Masters, via Wunderblog

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.

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 co-founded the Weather Underground. This piece was originally published at the Wunderblog and was reprinted with permission.

Related Post:

Increasingly Variable Summer Rainfall in Southeast Linked to Climate Change A new study by a Duke University-led team of climate scientists suggests that global warming is the main cause of a significant intensification in the North Atlantic Subtropical High (NASH).

The NASH, commonly referred to as the Bermuda High, is an area of high pressure that forms each summer near Bermuda, where its powerful surface center helps steer Atlantic hurricanes and plays a major role in shaping weather in the eastern United States, Western Europe and northwestern Africa.

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18 Responses to Did Climate Change Have A Role in Hurricane Sandy’s Unusual Track Into New Jersey?

  1. prokaryotes says:

    Isn’t it very strange that another storm is predicted to hit the area?

    Maybe this is the new pattern…

  2. Hmm. Didn’t consider the negative pressure over N.J., only the high pressure over Greenland. Maybe the two acted together, with the high pressure steering the storm and the low pressure helping suck it into shore? I do remember that Sandy unexpectedly picked up speed a couple of hours before it hit shore.

    Any help for us non-specialists is appreciated.

  3. Joan Savage says:

    I really like this piece, but the Vagabond Hurricane was not the only late-season hurricane to affect the upper Mid-Atlantic and Northeast.

    Hurricane Hazel developed in mid-October 1954, made landfall in North Carolina like a ‘regular’ hurricane, but then resembled Sandy as it moved inland and northward, complete with encounter with an Arctic cold front.

    Sandy has more areal extent, more ability to develop a wide-and-high storm surge, and made landfall further north than Hazel, but the elements of the storm track have shown up – rarely – before this. I want to be careful in presenting the climate change components of Sandy’s behavior in a way that others like me, who remember Hazel, can grasp without technical expertise.

    • Thank you, Joan.

      I bumped into a denialist who brought up Joe Bastardi’s argument that this couldn’t have anything to do with global warming since Hazel was similar and took place in the 1950s. Couldn’t find anything really comparing the two until today, that Sandy made landfall further north, happened later in the year, and had a larger wind field.

      Of course, even if things were reversed in the case of these two storms, our understanding of climate change is that this sort of thing is what we should expect to sea more of in our future. Sea levels will be higher, particularly along the eastern seaboard, making higher storm surge more likely. There will be fewer but stronger hurricanes. With the heating of the oceans, hurricane season will expand, with hurricanes showing up earlier and later in the year. Their range will extend further north. The jet stream will slow and meander more, making negatively tilted troughs more likely. There will be more blocking highs later in the year as the Arctic spirals further to ice free conditions. So even if this sort of thing has happened before, we should experience it more frequently, and more frequently as time goes on.

      The fact that denialists have to reach back that far to find something similar strongly suggests that this sort of thing is highly unusual, or at least has been, and our understanding of the physics involved strongly suggests that this sort of thing will become much more frequent.

  4. A.J. says:

    Interesting stuff. This adds another possible influence to those typically highlighted in the media. I wonder, though, if certain news outlets are at risk of appearing to overstate the climate change connection, given how people like Kevin Trenberth are treating it. He acknowledges the effects of warming and rising seas, but suggested that the human influence was small (though “important”), and much of the event was a “crap-shoot”:
    http://www.loe.org/shows/segments.html?programID=12-P13-00044&segmentID=1

    Of course, a lot of the concern is about the future, and climate change acceleration. And one thing I’ve been questioning is whether saying the seas have warmed about about one degree F tells the whole story, given that the extra warmth isn’t evenly distributed, spatially or temporally. It would seem that it can be “pooled” to some extent by the oceans, and modulated by variability in heat exchange with the deeper ocean. So presumably the regional anthropogenic effect can fluctuate some, just as natural factors can.

    • Mark E says:

      Some have estimated how much of the extra warmth (BTUs) in the “unusually warm “ocean current was due to AGW.

      BUT….. even if the rest of the extra BTUs in that current were not attributable to a human SOURCE no one seems to be asking whether humans played a role in making them appear in that unusual place/time/concentration.

      Reductionist science will only look at the human signal in terms of the extra units of energy the climate system acquires.

      Systems science will also look at how humans are changing the way all the units of energy slop around – whether they apportioned to AGWs extra warming or for lack of a better phrase – just normal pre-AGW warming.

      So its not just how many extra BTUs are we collecting…. its how are we changing the distribution of ALL of them that we should think about.

      • Timeslayer says:

        Great point Mark.

        In other words, if there had been no anthropogenic climate change in the past 50 years, would Sandy have occurred as it did? No, it would not have. A basic understanding of causality gives a definite answer on this.

        TS

  5. David Heintz says:

    Think of the inverse. Is it possible GW and sea rise DID NOT have an effect? Is it possible GW and sea rise made Sandy LESS powerful than otherwise? “.. can cause blocking ridges …” ? How about, Is it possible GW DID NOT redirect Sandy to the NW?

    If the obvious is only “possible” the “inevitable” can be discounted. Just sayin’.

    • Leif says:

      Think of it this way David: People the world over readily accept the scientific fact that changing a patch of South Pacific from warm to cool by only a couple of degrees C, and the resulting comparatively narrow El Nino/La Nina current across the Equatorial Pacific to South America, can have a profound effect on the weather. Not only here in the United States, but to a lesser degree Europe and Africa.
      On the other hand, transforming a much closer, (boarders in many cases), highly reflective patch of earth from significantly bellow freezing to dark open water above freezing, a difference of 10′s of degrees C and it is all business as usual? Couple that with an area that is larger than the states of Alaska and Texas combined and it is all just going to be “Ho Hum”! Get real. I am telling you, Science is telling you, and the on the ground reality are all raising red flags here. Of course vested interests are spending big bucks trotting out “red herrings” as fast as they can. Perhaps that must be factored into the attitudes of the masses, you think?
      Time to toast the deniers, not the Kidders…
      We all pay fees to dump garbage, waste water and more. Corpro/People dump tons for free and accumulate mega-bucks. Even get tax subsidies. The GOP don’t fund abortion. Fine. A precedent! Why must my tax dollars fund the ecocide of the PLANET via fossil subsidies?!!! We’re talking “MORALS” here. Try throwing 19 pounds of paper cups out the car window for each gallon of gas you burn. Who is making money here and who is losing? Toxins verses paper cups? (I bet you could be real creative about increasing your trash stream if it were paper cups.) Even absorb a “slap on the wrist” fine once in awhile. Surely a good lawyer on retainer. Once established perhaps even a congressman or two.
      I pay $150/ton to dump my household garbage. $50/T to recycle yard waste. Waste water fees, of course. I even have a rain water run off fee of $5/m. (guide lines here?) Yet Corpro/people piss all over themselves at the thought of $25/ton for TOXINS! Sweet Jesus… They are making billions, I get ~$30/day to stay alive and must fund health insurance. Go Figure!
      In brief:
      Stop profits from the pollution of the commons.
      Go Green, Resistance is FATAL to Earth’s life support systems, that is a given and proven. Socially enabled capitalism is a failed paradigm.

      • David Heintz says:

        Thank you. But I guess I was being unintentionally ironic, suggesting we should no longer think of the “possible” connections, but to force the concept of the certain and the undeniable. We’re on the same page, I just said it weird.

        • prokaryotes says:

          btw what are the odd’s for 2x, 500 year storms within 2 years?

          Last year Irene and now Sandy. And then you have the Derecho event from earlier this year. All events which are called very rare.

      • dick smith says:

        Several interesting anologies. I especially liked comparing the size and temperature variations of ENSO variations to the change from ice to blue sea in the arctic. It doesn’t prove anything, but it helped make the concept easier to understand and prima facie credible.

  6. Steve Bloom says:

    Joan, Sandy’s survival so far north of Cape Hatteras so late in the season is what sets it apart. Note in particular the extreme shear winds it had to survive starting around the Bahamas. Had SSTs not been so high, it would have been blown apart.

    • Joan Savage says:

      Steve, I think the 500+ mile swathe sets Sandy apart, and the swathe is easy to link to persistent late season SST, therefore climate change.

      The elements of a blocking pattern and a south-reaching Arctic cold front may become more frequent with climate change, but it’s early to say a new pattern has been established. My point is that some aspects of Sandy are more strongly correlated to global warming than others. It’s only fair to compare and contrast it to other late season hurricanes that made it into the northeast.

  7. The loss of Arctic sea ice has certainly had an effect on the atmosphere:

    Arctic Alaska’s Autumn Anomaly: Record Warm October at Barrow
    http://capitalclimate.blogspot.com/2012/10/arctic-alaskas-autumn-anomaly-record.html

  8. Paul Klinkman says:

    We might also ask what didn’t happen with Sandy.

    In 1938 the eye of a category 3 hurricane hit Westerly, Rhode Island. On its windward side, all of shallow Narragansett Bay turned into a ramp for piling up water into Providence. 600 people died. Sandy was a category 1, but with a huge wind field.

    So, we should think not about another Sandy hitting just before Halloween but an occasional category 3 strike (or, with climate change, a category 5) on the side of Manhattan, scattering the bowling pins. The bowling term “Brooklyn” also comes to mind.

    Movable gates across the Hudson and East Rivers will stop most floods, but the buildings may or may not be designed to survive the enhanced winds. What good is a freedom tower when it’s leaning over?

  9. Leif says:

    And now the European weather prediction center and the US prediction center are aligning with another serious storm next week. Not as bad as Sandy but damaging NE winds and snow inland. (Cliff Mass Weather blog has a report.) Still a ways out so lots of room for changes but it is yet another well formed large low forming.