Superstorm Sandy Slams the North East with Winds, Storm Surge, and Flooding

30-Oct-12

Sandy made landfall on Monday night around 8 pm EDT, October 29, near Atlantic City, NJ. Maximum sustained winds at the time were estimated at 80 mph, and the broad wind field stretching out hundreds of miles from the center brought damaging wind gusts and coastal surges from Virginia to New England. Sandy was an extraordinary storm - a combination of 3 different weather systems coming together and morphing into a large super storm. Arriving with a spring tide (when the sun, moon, and earth are in alignment, causing the tide range to be at maximum), storm surge combined with tidal variations exacerbate flood losses.

Sandy was a post-tropical storm system at landfall and it continued to slow down after landfall, exacerbating the wind and storm surge impacts along Virginia to New England. Record storm surge heights were observed in New Jersey and New York.

Hurricane Sandy is a major event that is responsible for multiple fatalities and significant damage and disruption. Sandy has struck the US region with the highest population and GDP contribution. Against this backdrop, Sandy is expected to produce very high absolute damage and loss numbers, but low losses as a portion of the underlying economy and asset base. EQECAT is currently working to produce a refined post-event loss estimate for this event.

Storm Track

Early Monday afternoon, a low-pressure trough in the eastern US began to steer Sandy to the northwest, then west-northwest, as it accelerated to 28 mph. Just a few hours before landfall, the remnant of the tropical core of Sandy was finally absorbed by the upper level trough and Sandy was officially declared a post-tropical storm. This final transition had only a small effect on Sandy's intensity, dropping its maximum winds to 80 mph just prior to landfall. Sandy also slowed slightly before landfall, moving at 23 mph to the west-northwest as the center of circulation crossed the coast near Atlantic City, NJ. Sandy continued to slow down after landfall, and is expected to move slowly through central and western Pennsylvania today.

As a post-tropical storm, Sandy made an almost perpendicular landfall in southern New Jersey at a west - northwest heading. The track of Sandy was unusual – it is far more typical of hurricanes and extra-tropical storms at this latitude to be on a north or northeastern path. The track geometry, including the continuing track west through Pennsylvania, contributed to the damage caused by Sandy. As Sandy headed west, the winds impacting the coastlines of New York and New Jersey continued to push water onto shore. A hurricane on a more typical track to the north or northeast would have produced winds that pushed the water offshore after the eye of the storm had passed landfall. Sandy's near- perpendicular landfall and very large size, contributed to storm surge and the resulting dramatic reports of coastal flooding.

Storm Winds

The primary agent of damage from hurricanes is wind, as wind gusts cause direct damage to buildings from the dynamic loading of wind pressure, and indirect damage from falling trees and falling debris. Based upon a combination of observed and forecasted wind speed measurements, EQECAT has produced an approximate map of the gust wind field from Sandy (below). Some of the preliminary reported wind speeds (gust, mph) from Sandy include:

  • Atlantic City, NJ - 77 mph
  • Cape May, NJ - 73 mph
  • Clifton, NJ - 80 mph
  • Coney Island, NY – 69 mph
  • Dennisville, NJ (Near Cape May) - 81 mph
  • Greenwich, CT - 70 mph
  • Islip Airport, NY - 90 mph
  • JFK Airport, NY – 79 mph
  • Montclair, NJ - 88 mph
  • New Haven, CT - 85 mph
  • Newark Airport, NJ - 78 mph
  • Ocean City, NJ - 60 mph
  • Sandy Hook, NJ - 87 mph (buoy)
  • Sandy Hook, NJ - 81 mph (onshore)
  • Surf City (Ocean County), NJ - 89 mph
  • Tompkinsville, NY – 90 mph
  • White Plains Airport, NY - 72 mph

EQECAT's windfield map and the wind observations are consistent with an uncharacteristically large Category 1 hurricane. Large portions of coastal New Jersey New York and southern New England reported wind gusts from 60 to 90 mph during this event. The slow translation speed of Sandy also caused many locations to endure high wind speeds for many hours, contributing to damage.

Superstorm Sandy Peak Wind Gusts - October 30, 2012

Superstorm Sandy Peak Wind Gusts - October 30, 2012
Source: EQECAT, Inc.

Affected Area

Hurricane Sandy has traversed the largest population centers along the US eastern seaboard, and areas with the highest population density. An estimated 50 million people live or work in the areas affected by Sandy. EQECAT's Insured Exposure Data (IED) identifies about $18 trillion in insurable assets in the regions affected by winds from Sandy.

Storm Surge

Significant storm surge levels were seen along much of the affected coast in New Jersey, Long Island, Connecticut, and Rhode Island. Severe flooding occurred in Manhattan and other portions of New York City and the New Jersey metropolitan areas. Record storm tides were also experienced in New York Harbor. A tide gauge at Battery Park (southern tip of Manhattan Island) recorded a record of 13.88 feet during high tide around 9 pm EDT Monday, as strong southeasterly winds pushed water into the confined area. The previous record of 10.5 feet was experienced during Hurricane Donna in 1960.

Preliminary Water Level vs. Predicted Plot - October 30, 2012

Preliminary Water Level vs. Predicted Plot - October 30, 2012
Source: NOAA

Levee breaches were reported in New Jersey, and several cases of localized flooding were reported in New Jersey, New York, and the DelMarVa Pennisula (Delaware, Maryland and Virginia). Mass transportation was also significantly impacted. The 108 year old New York Subway system was shut down with reports of several flooded stations and train tunnels.

Super Storm Sandy Potential Storm Track - October 30, 2012

Super Storm Sandy Potential Storm Track - October 30, 2012
Source: National Hurricane Center (NHC)

At 11 am this morning, Tuesday, October 30, 2012, the center of Sandy was 145 miles west of Philadelphia, PA, and was moving to the west at 10 mph. Maximum sustained winds were 45 mph, the center is expected to turn northward into western New York State this afternoon, and into Canada by Wednesday.

Briefing: Modeling the Effects of Superstorm Sandy

On Thursday, November 1, EQECAT will host a briefing, Modeling the Effects of Superstorm Sandy, at 3 pm Eastern / 12 pm Pacific. Please join EQECAT as we provide a first glimpse review of the information that we have gathered so far and our conclusions about the storm to date.

 

Engineering Risk and Site Evaluations

EQECAT Inc. and ABS Consulting are part of the ABS Group of Companies. ABS Consulting offers on-site risk assessments, evaluations and structural engineering services with more than 1,800 employees worldwide. ABS Consulting engineers and scientists use EQECAT catastrophe risk models to provide risk assessments, in addition to having performed inspections or repairs after more than 100 earthquakes and 25 major windstorms. Learn more about ABS Consulting's natural hazard risk assessment capabilities.

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