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Atlantic Warm Pool Influences on U.S. Land-Falling Hurricanes
Wang, C., Liu, H., Lee, S.-K. and Atlas, R. 2011. Impact of the Atlantic warm pool on United States landfalling hurricanes. Geophysical Research Letters 38: 10.1029/2011GL049265.

The authors note that the 2010 Atlantic hurricane season was extremely active, with 19 named storms, of which 12 were hurricanes and 5 were major hurricanes. However, they also note that during the 2010 hurricane season "not a single hurricane made landfall in the United States." So what's going on here?

What was done
Wang et al. attempt to get to the bottom of the question by focusing their attention on tropical cyclones (TCs) that form in the Atlantic Ocean's main development region (MDR), utilizing both observations and model experiments.

What was learned
Working with data for the period 1970-2009, the two researchers found that a large Atlantic Warm Pool (AWP, a large body of warm water that includes the Gulf of Mexico, the Caribbean Sea and the western tropical North Atlantic) tends to produce a greater number of TCs, while at the same time it shifts the TC genesis region eastward, so that "it increases the chance for a TC to move northward without making landfall in the United States." And they add that "a large AWP also induces barotropic stationary wave patterns that weaken the North Atlantic subtropical high and produce the eastward steering flow anomalies along the eastern seaboard of the United States."

What it means
It is interesting to note that although several studies have indicated that Atlantic Ocean hurricanes of the past few decades have been no more numerous than they were in prior cooler periods -- see Tropical Cyclones (Atlantic Ocean - Global Warming Effects) in our Subject Index -- in this special case, where extra warmth does appear to enhance their numbers, they seem to be preferentially steered away from the coastal regions of the United States, sparing the country much of the extra damage they might otherwise cause.

Reviewed 28 December 2011