A developing El Nino is not usually good news, but signs that the equatorial eastern Pacific Ocean is heating up should elicit smiles from hurricane-wary residents of the East and Gulf coasts.
Officially, the National Hurricane Center is predicting an average season for the Atlantic Basin, with a 70 percent chance that there will be nine to 14 named storms, of which four to seven would become hurricanes, with one to three of those achieving major hurricane status.
However, forecasters freely acknowledge that this outlook is something of a punt. It takes into account recent history, which since 1995 has meant greater than normal hurricane activity, as well as emerging atmospheric trends, which point to a below-average number of storms. The hurricane season that runs from June through November could go either way, say the weatherfolks.
El Nino is the most important of the emerging atmospheric trends meteorologists must consider when making predictions about the upcoming hurricane season. After a cold episode—often called La Nina or, sometimes, El Viejo—sea surface temperatures in key regions of the Pacific have been warming for several months. Typically, El Nino emerges during the Northern Hemisphere summer, reaches a peak near the end of the year (hence the name, given generations ago by South American fishermen who observed that “The Child” appeared near Christmas), and fades away during the following spring.
Strong El Ninos usually produce global weather mayhem. Droughts parch tropical rain forests in Indonesia and Australia, floods batter the desert coastlines of Peru and Chile, and monsoon rains that support vital crops in India become erratic. In winter, powerful Pacific storms smash into California, and twisters scoot across the U.S. Deep South. Fish may wander far from their usual habitat to find hospitable water temperatures, leaving fishermen empty-handed.
But, as they say, it is an ill wind that blows no good. El Nino often produces strong westerly winds across the tropical Atlantic. These winds can shear apart a tropical cyclone before it reaches hurricane force. Studies have shown that the chance of a hurricane making landfall in the United States during El Nino is only one-third as high as in a typical year.
Still, the chance of a hurricane strike is not zero, even during El Nino. A mild El Nino emerged in June 2004 and lasted until March 2005. In spite of this, the 2004 season produced nine Atlantic hurricanes, including Ivan, a Category 5 hurricane that devastated the Caribbean, and six other storms that struck or grazed the United States — four in Florida alone. Max Mayfield, then the head of the National Hurricane Center, said it felt as though the Sunshine State was wearing a meteorological “kick me” sign.
If hurricanes worry you, be hopeful for a nice El Nino, but don’t let down your guard.