26 October 2012

ICAT on Hurricane Sandy Damage Benchmarks

ICAT just sent out this summary (here in PDF) of an analysis using the ICAT Damage Estimator (based on our normalized hurricane loss database):
The ICAT Damage Estimator (www.icatdamageestimator.com) can be used to obtain statistics regarding historic storms that have followed similar paths to Hurricane Sandy’s current forecast path. For this analysis, the Active Storms search feature was used to select all historic storms that have made landfall within the current range of computer model forecasts. This range includes the coastline from near the MD/VA border on the DelMarVa Peninsula to the eastern edge of Long Island, NY. The ICAT Damage Estimator shows that there have been 7 damaging tropical cyclones that have made landfall along this segment of coastline since 1900. The tool shows the storm parameters, the damage at the time of landfall, and the estimated damage if the storms were to make landfall in 2012. The 2012 damage estimations are made by “normalizing” the data by adjusting for population change, inflation, and change in wealth per capita.

The most damaging storm to make landfall within the current range of computer model forecasts was the New England hurricane of 1938, which would cause an estimated ~$47B in damage today. However, this storm was a category 3 hurricane when it made landfall, while Sandy is only expected to have category 1 force winds. Of the 7 storms selected, only two made landfall as category 1 hurricanes. Hurricane Agnes of 1972 made landfall with 85 mph sustained winds near New York City and would cause an estimated $19B in damage today. Agnes initially made landfall over the FL Panhandle, then moved NE and emerged off the NC coast. As it approached New England, the
storm strengthened as it underwent extratropical transition, which is also expected to occur with Hurricane Sandy. Hurricane Agnes’s impacts were felt across a very wide area of the Northeast. Hurricane Belle of 1976 also had 85 mph winds, but moved much more quickly than Agnes and was weakening as it made landfall. It is estimated that Belle would cause less than $1B in damage today.

As can be seen from the storms selected by the ICAT Damage Estimator, the sample size of category 1 hurricanes making landfall along the Northeast is not very large. While Agnes appears to be the most similar to Sandy, it made landfall near New York City, which explains why the damage estimates are so high. Hurricane Irene of 2011 officially made landfall further south, but impacted a similar area that will be affected by Hurricane Sandy. That storm caused ~$7B in damage, but was not quite as strong as Sandy is expected to be. This data can be used as a benchmark to assess the range of possibilities for Sandy’s impact.
Full report here in PDF.