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Rare April tropical storm forms in Atlantic, marking abnormally early start to hurricane season

Tropical Storm Arlene, April 20. (NOAA)

Atlantic hurricane season doesn’t officially begin until June 1, but 2017’s edition is off to a premature start thanks to the formation of Tropical Storm Arlene.

Arlene formed Thursday in the middle of the Atlantic Ocean, some 815 miles west of the Azores. Early Friday, it was moving westward at more than 30 mph with maximum sustained winds near 50 mph. But Arlene is not expected to be around for long. The National Hurricane Center expects it to get absorbed by a nearby nontropical storm and dissipate later Friday.

As it’s no threat to any land, Arlene is more or less just a curiosity for forming so early in the year. It is only the second named storm on record to develop in April since forecasters began monitoring the Atlantic using weather satellites in 1960. The other named April storm, Ana, also formed April 20, in 2003.

Before weather satellites, it is quite possible — if not likely — additional tropical storms formed in April, but “this type of storm was practically impossible to detect,” the National Hurricane Center said.

Arlene becomes the sixth preseason formation in the past six years — the others were Alberto and Beryl in 2012, Ana in 2015, and Alex and Bonnie in 2016.

Despite the unusually early kickoff to Atlantic hurricane season, it is not forecast to be particularly active. The seasonal hurricane forecast from researchers at Colorado State University calls for a slightly less active than normal season, with 11 named storms, four hurricanes and two major hurricanes.

2017 hurricane outlook: Colorado State predicts a slightly below-average season