1st tropical depression of season forms far from land

First tropical depression of the year forms in the Atlantic

Tropical storms and hurricanes require a warmer ocean surface temperature to get going (about 82F/28C), whereas subtropical lows are possible with sea temperatures of about 70F/21C.

Tropical Storm Arlene developed on Thursday from Tropical Depression One, which itself emerged from a subtropical system which developed Wednesday.

It may have formed in open water, well away from any human habitation, but Sub-Tropical Depression One has already made a name for itself.

Little change in strength is expected throughout the rest of Arlene's lifespan, and the storm will have no direct impact on any land areas.

The arrival of Tropical Depression 1 is a reminder that hurricane season is around the corner.

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You'd be right to think it's very early for development in the Atlantic.

While our official hurricane season doesn't start for another month or so, don't tell Mother Nature.

The wind fields of new tropical cyclones will be depicted a couple of new ways.

There has been five other disturbances (including Tropical Storm Ana) that tried to develop since the satellite era began in the early 1960s. "Unexpectedly, the subtropical cyclone became a tropical depression this morning, and then it intensified to a tropical storm".

The next update from the National Hurricane Center will be issued at 11 p.m. Thursday. In fact, storms have formed before June 1st in four of the last six years. The 2016 season got a jump-start when Hurricane Alex formed january 14. When April tropical systems emerged in 1973 and 1992, storm activity was below average.

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