Tag Archives: Superstorm Sandy

Are Late, Wet Hurricanes Becoming a Trend?

By Max Dorfman, Research Writer, Insurance Information Institute

Hurricane Zeta became the 11th named storm and 6th hurricane to hit the United States yesterday, as the extremely active 2020 Atlantic hurricane season continues. Zeta struck just one day before the eighth anniversary of Superstorm Sandy.  

Sandy was the deadliest and most destructive hurricane of the 2012 Atlantic season, causing $70 billion in economic damages and resulting in over 70 fatalities when it made landfall in New Jersey. It surprised an under-prepared New Jersey and New York City when it arrived. Sandy was no longer a hurricane when it made landfall, having undergone transition into an extra-tropical (e.g., non-tropical) low pressure area earlier that day. Although it was no longer a hurricane upon its arrival, it was still immensely damaging due especially to its large size, as well as its interaction with a strong storm system moving east.

There is some history of late-season hurricanes, but Colorado State University climate scientist and Triple-I non-resident scholar Dr. PhilKlotzbach says it would be an overstatement to call this a trend.

“We haven’t really seen a trend in late-season hurricane activity,” Klotzbach said. “A lot of what drives late-season hurricane activity is the phase of El Niño or La Niña. If you have a La Niña, like we have this year, which is colder water in the eastern and central tropical Pacific, that tends to reduce the vertical wind shear that typically tears apart hurricanes. Reduced wind shear tends to keep the hurricane season going longer.”

Klotzbach noted that 2012 was neither an El Niño nor La Niña year.

What made Sandy different?

Hurricane Sandy was a massive aberration.

“Normally, when storms spin up in the Caribbean and move northeast, they continue moving northeast into the North Atlantic and do not significantly impact land,” Klotzbach said. “Unfortunately, with Sandy it started moving northwest.” Indeed, Sandy managed to wreak havoc across the Northeast and other parts of the country, including dumping as much as 36 inches of snow in West Virginia.

“There was a big high-pressure area over the Atlantic Provinces of Canada that built to the north of Sandy and drove the storm to the northwest,” Klotzbach explained. “The sustained winds were strong, maxing out around 80 mph, but the real problem with Sandy was its tremendous size.”

Given the large size of Sandy, it drove a huge storm surge that spanned from New Jersey to Connecticut including New York City.

“The storm surge from Sandy was incredible,” Klotzbach said. “The surge also coincided with astronomical high tide, which exacerbated the inland penetration of water from the coast. For example, the storm tide at the Battery on the southern tip of Manhattan exceeded 14 feet.”

What we can do

The public needs to be more informed about the dangers of these kinds of storms. Even though Sandy wasn’t technically a hurricane when it made landfall in New Jersey, Klotzbach believes the transition of the storm from hurricane to extra-tropical may have been confusing for people who didn’t understand that the storm wasn’t less of a threat after its classification was altered.

“Just because the storm was changing in structure doesn’t mean it wasn’t a significant threat,” Klotzbach said. “It had just about the same maximum winds as when it was a hurricane. People also looked at the maximum wind and saw that it was 80mph and didn’t think it was that much of a problem. But it was an enormous storm, so the surge was much bigger than what you’d expect from an average category 1 hurricane. From that perspective, there were challenges with conveying the magnitude of the threat.”

Indeed, Klotzbach gives a dire warning about the risks associated with not taking these storms seriously.

“A lot of it is in the messaging when these storms are going from tropical to extra-tropical,” he said. “We need to convey how these threats are changing and that just because a system is becoming extra-tropical doesn’t mean that the threat has gone away. We need to get more social science integrated into meteorology to better convey these results to the general public.”

Cross-posted from Triple-I’s Resilience Accelerator.

Superstorm Sandy

By Phil Klotzbach, lead author of the Colorado State University (CSU) hurricane forecasting team, and I.I.I. non-resident scholar.

Five years ago this month (October 29), Superstorm (hurricane until a few hours before landfall) Sandy made landfall along the coast of New Jersey just northeast of Atlantic City.  Sandy was one of the most devastating hurricanes to hit the northeast United States, causing more than 70 fatalities and $50 billion dollars in damage. It was the deadliest Northeast United States hurricane since Agnes (1972) and the 2nd most expensive United States hurricane on record behind Katrina (2005).  While heavy rainfall and strong winds were part of Sandy’s legacy, the primary cause of the massive destruction and damage that occurred was due to high storm surge levels.

Sandy developed in the SW Caribbean on October 22 (Figure 1). This region is a typical hotbed for October Atlantic hurricanes.  The system slowly intensified, eventually reaching hurricane strength before hitting Jamaica as a Category 1 hurricane.  It briefly reached major hurricane strength (Category 3+ on the Saffir-Simpson Wind Scale) before making landfall in Cuba.

Figure 1: Track of Hurricane Sandy from its formation in the SW Caribbean until its dissipation in the northeast United States.  Figure courtesy of National Hurricane Center.

Landfall in Cuba weakened Sandy somewhat, and the system began to undergo structural changes as it interacted with a large upper-level low pressure area.  This upper-level low caused the inner core to lose intensity, but it also caused the storm to grow considerably in size.  Sandy weakened to a tropical storm, but then vertical wind shear (the change in wind direction with height in the atmosphere), began to abate and Sandy was able to re-intensify to hurricane strength.  The storm, however, retained its large, sprawling circulation. (Figure 2).  Tropical storm-force winds extended more than 900 miles away from the center of the circulation as it approached the United States coast, making it the largest Atlantic hurricane on record (since 1988).

Figure 2: Infrared satellite imagery of Hurricane Sandy on October 29 showing the large, sprawling nature of its circulation.  Figure courtesy of NOAA.

A large blocking high to the north of Sandy caused the storm to track to the northwest (Figure 3).  Once Sandy had finished transiting the warm waters of the Gulf Stream and moved over cooler shelf waters near the New Jersey coast, it completed its transition into a post-tropical cyclone several hours before landfall.

Figure 3: Mid-level weather pattern causing the anomalous track that Hurricane Sandy took.  Strong high pressure to the north of Sandy prevented recurvature and caused Sandy to track towards the northwest.  Figure courtesy of National Hurricane Center.

While the maximum intensity at the time of its New Jersey landfall was 80 mph – equivalent to a Category 1 hurricane – the storm’s large size triggered huge amounts of storm surge.  In addition, tides were running higher than normal, due to the lunar cycle; storm tide values shattered records in parts of New York City.  At the Battery, Manhattan’s southernmost tip, the storm tide exceeded 14 feet, which was more than four feet higher than the previous record set during a winter storm in December 1992.   Many other areas along the coast of New Jersey and in New York City reported storm surge levels of 5-8 feet from Sandy which combined with astronomical factors to cause massive inundation.

Sandy’s transition from hurricane to post-tropical cyclone immediately prior to landfall as well as the massive size of the system has helped us to refocus efforts in the five years since the storm to clearly delineate between the Saffir-Simpson Wind Scale category and potential impacts that the storm may generate. Just because a system transitions from a hurricane into a post-tropical system does not mean that its impacts have been ameliorated. While it has now been five years since Sandy’s landfall, it will forever be remembered in the northeast United States as an incredibly damaging storm.

Marine Insurers Feel the Impact of Sandy too

As we look ahead to the start of the 2013 Atlantic hurricane season marine insurers are among those that will be closely monitoring forecast storm activity.

Annual spring statistics recently released by the International Union of Marine Insurance (IUMI) noted that the cost of Superstorm Sandy to the global marine market has been put at between $2.5 billion to $3 billion – effectively wiping out the entire U.S. marine premiums for 2012.

The statistics which cover the cargo, ocean hull and offshore energy sectors remain a litmus test for the marine insurance market and the impact of Sandy will define 2012 in the eyes of underwriters, IUMI said.

While Superstorm Sandy’s main areas of impact were the states of New York and New Jersey, it was one of the largest storms ever and its impact stretched over 1,000 miles from the Great Lakes to Boston.

In its  analysis of the cargo market, IUMI noted:

The total insured loss from Sandy is currently estimated to be between $25 billion-$30 billion of which approximately 10 percent or $2.5 billion-$3 billion is for the marine business.

It’s still unclear how much of that was for ocean cargo, but we do know that major industry groups such as automotive, coffee/cocoa trade and fine arts were particularly hard hit. There is also a substantial inland marine loss.

To put the claim in perspective this one loss has eroded an entire years worth of premium for the whole U.S. marine market.†

Insurance Journal has more on this story here.

Lessons learned from Superstorm Sandy are among the topics to be addressed at the 20th Biennial Marine Insurance Issues Seminar sponsored by the American Institute of Marine Underwriters (AIMU) on May 8 in New York City. The conference will be held at the New York Marriott Downtown, 85 West St.

To register for the seminar or for further information click here.