Influences of Large-Scale Climate on Whether Hurricanes Make Landfall in the United States

We use observations and numerical model experiments to examine the influences of large-scale climate on U. S. landfalling hurricanes. It is shown that the Atlantic warm pool (AWP) – a large body of warm water comprised of the Gulf of Mexico, the Caribbean Sea and the western tropical North Atlantic – plays an important role in the hurricane track. An eastward expansion of the AWP shifts the hurricane genesis location eastward, decreasing the possibility for a hurricane to make landfall. 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. Due to these two mechanisms, hurricanes are steered toward the northeast without making landfall in the U. S. during large AWP years. As an example, the AWP in 2010 was extremely large and the 2010 Atlantic hurricane season was very active; however, no hurricanes made landfall in the United States. Although the La Niña event in the Pacific may be associated with the increased number of Atlantic hurricanes, its relationship with landfalling activity has been offset in 2010 by the effect of the extremely large AWP. The impacts of other climate factors on the hurricane track are also discussed.