Long Island Hurricane Climatology

Epic Hurricanes (Hughes)	Hurricane Frequency (Scheffner & Butler, 1996)
1938 1893 1821 1815 1635	Click for Full Size

New Yorkers give little thought to hurricanes since Long Island is so far from the warm, tropical oceans that feed hurricanes. However, according to the 1984 Hurricane Damage Mitigation Plan by the Long Island Regional Planning Board, several hurricanes and 15 tropical storms have made landfall in this area since 1886. According to historical record, there have been five "epic hurricanes" (Category 3 or higher on the Saffir Simpson Scale) in the years 1938, 1893, 1821, 1815, and 1635 (Hughes).

An empirical study of 20 past hurricanes that have impacted the New York City and Long Island coast regions by Scheffner and Butler (1996) found that the return period of a category 3 or greater hurricane is approximately 80 years. A strong category 3 or minimal category 4 hurricane has a return frequency of approximately 200 years. (Click graph to the right for larger image.) Therefore, it is not unlikely that another "epic" hurricane will strike the Long Island coastal region in the coming decades.

Research done by hurricane experts at the National Center for Atmospheric Research (NCAR) reveals that hurricane frequency in the Atlantic Ocean and Caribbean Sea regions runs on a 20-30 year cycle. (Time, 1998) The graphic to the left (Risk Prediction Initiative, 1998) clearly illustrates this cycle. The last intense period was in the 1950's and 1960's with a lag between 1970 and 1994. The hurricane frequency is on the upswing once again which increases the chances for landfall everywhere along the east coast of the U.S.

Unfortunately, in the past few decades, the coastal population has also increased substantially which further increases the hurricane risk. Even though more sophisticated forecasting tools such as satellites and Doppler radar are providing more lead-time for issuing warnings, the threat of massive deaths remains fairly high due to the increased coastal populations. Source: USGS, 1998 Click for Larger View

Source: Time Magazine, 1998 The tables to the right show probability estimates for the occurrence of various disaster events (including hurricanes) that could impact the U.S. in the future. While it may not be surprising to see that there is a >99% likelihood of at least 10 deaths from a hurricane in the next 10 years, it should be noted that the data indicates a 71% probability of 1,000 deaths from a hurricane in the next 20 years!

Climate Change and Hurricanes:

According to a review of the most recent literature, Vechi, Swanson, and Soden (2008) conclude that predicting the future of hurricane activity is at a crossroads. Vechi et al. compared the observed relation of the power dissipation index (PDI) vs. sea-surface temperatures (SST) in the main development region of Atalntic hurricanes. (PDI is the cube of the instantaneous tropical cyclone wind speed integrated over the life of all storms in a given season; more intense and frequent basinwide hurricane activity lead to higher PDI values.) There are two very different futures depending on whether absolute SST or relative SST controls PDI.

Figure 29b (ibid) shows PDI anomolies based on absolute SST.

Figure 29b: PDI anomolies based on absolute SST

By 2100, the lower end of the model projections shows a PDI comparable to that of 2005, when four major hurricanes (sustained winds of over 100 knots) struck the continental United States, causing more than $100 billion in damage. The upper end of the projections exceeds 2005 levels by more than a factor of two. Combined with rising sea levels, coastal communities face a bleak future if absolute SST determines hurricane activity and strength.

Figure 29c (ibid) shows PDI anomolies based on "relative SST" which is the SST in the tropical Atlantic main development region relative to the tropical mean SST.

Figure 29c: PDI anomolies based on relative SST

A future where relative SST controls Atlantic hurricane activity is a future similar to the recent past, with periods of higher and lower hurricane activity relative to present-day conditions due to natural climate variability, but with little long-term trend.

Because the correlation of PDI vs. absolute SST and PDI vs. relative SST are equivalent, Vechi et al. conclude that more research is needed in this area.

The next section deals the future threat of New York hurrricanes and some worst-case scenario simulations of older events.

Geological Impact

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Future Hurricanes?

Scott A. Mandia, Professor - Physical Sciences T-202 Smithtown Sciences Bldg. 451-4104 mandias@sunysuffolk.edu <-- PREFERRED CONTACT METHOD http://www2.sunysuffolk.edu/mandias/ BOBBY v.3.2 approved site