Below-normal hurricane season forecast as El Niño returns

Meteorologists are forecasting a below-normal hurricane season thanks to the expected return of the climate phenomenon known as El Niño.

Forecasters at the Tropical Meteorology Project at Colorado State University predict about 11 named storms, four of them becoming hurricanes.

AccuWeather meteorologists are calling for 10 named storms, half of which could become hurricanes.

Both forecasts suggest a season that is slightly quieter than normal — on average, a dozen named storms and six hurricanes form in a given season.

That is common when El Niño is present because some of the climate conditions for which it is known tend to discourage tropical cyclones from forming and strengthening. For example, El Niño commonly brings high wind shear in the Atlantic, with varying wind speeds and directions at different levels of the atmosphere that inhibit cyclone development.

Tropical storms get a name when they develop a defined cyclonic circulation and maximum sustained winds of at least 39 mph. When those winds reach at least 74 mph, it becomes a hurricane, and if they surpass 111 mph, it is considered a “major” storm.

No major hurricane has made landfall in the United States since Hurricane Wilma in 2005. The meteorology project’s forecast suggests a 42 percent chance of that streak ending this year, and a 24 percent that a major hurricane strikes the East Coast.

Climate forecasters expect a weak or moderate El Niño by the end of summer, hurricane season’s peak. The climate pattern is marked by warm surface temperatures along the equator in the Pacific Ocean, sending heavier than normal precipitation across the southern United States and other parts of the world. In other parts of the world, El Niño triggers droughts.

This season’s list of hurricane names is the same one used in 2011, and starts with Arlene. This time around, however, any “I” named storm would be Irma instead of Irene — the latter name was retired after it wreaked havoc from the Southeast to New England, causing hundreds of thousands of power outages in the Baltimore region.

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