New Take on Pacific Warming May Improve Hurricane Prediction

Scientists have identified a new type of warming event in the tropical Pacific, which, compared to its better known counterpart, El Niño, has predictable effects on tropical cyclones in the North Atlantic. These findings may allow researchers to make more accurate predictions, earlier in the year, about how frequently tropical cyclones may blow over the United States Gulf coast and Central America, they report in the July 3 issue of Science. During an El Niño event, which is the warm phase of the air-sea temperature disturbance known as ENSO, the trade winds relax and the surface of the eastern Pacific warms up, affecting weather patterns around the world, including tropical cyclone activity. Hye-Mi Kim and colleagues now report that the central Pacific also warms up on a quasi-periodic basis, also with a large effect on atmospheric circulation. In a related Perspective, Greg Holland points out that as the ENSO cycle teeters between the El Niño and La Niña phases in the spring, the system can be quite unpredictable. By the time an El Niño event is clearly underway in June, the insurance industry, for example, has already locked in its annual rates. In contrast, central Pacific warming events occur in a more predictable way, and these events are associated with tropical cyclones that occur more frequently and are more likely to make landfall in North and Central America. The authors say that central Pacific warming events have likely been mistaken for El Niño events in the past, so teasing these two types of events should help researchers predict tropical cyclones. They also note that central Pacific warming events have become increasingly frequent in recent decades, though the reason why is still unclear.

Article #14: "Impact of Shifting Patterns of Pacific Ocean Warming on North Atlantic Tropical Cyclones," by H-M. Kim; P.J. Webster; J.A. Curry at Georgia Institute of Technology in Atlanta, GA