Days away from the official start of Atlantic hurricane season, the first tropical system of 2018 formed Friday in the Caribbean Sea.

What is a subtropical storm and why you should care

The first tropical system has formed in 2018, and it’s heading straight for the Gulf of Mexico and Gulf shore. 

Subtropical Storm Alberto should affect most people in the Southeast over the next week, but why is it called “subtropical” and not just a tropical storm?

» For a detailed forecast, visit The Atlanta Journal-Constitution weather page.

In practical effect, there isn’t too much different. Both subtropical and tropical storms brings strong winds, stronger gusts and lots of rain with them, but they get their energy from different sources, Channel 2 Action News chief meteorologist Glenn Burns said.

Subtropical storms are colder than tropical storms, meaning they aren’t powered by warm water.

“(Subtropical Storm Alberto) is not feeding on water evaporation in the ocean,” Burns said.


This also makes them typically weaker than tropical storms, although they can develop into tropical storms

If either type of storm reaches sustained winds of 74 mph, it then becomes a hurricane, but that’s less likely to happen with subtropical storms due to the lack of warm water. It’s mostly a winter-type weather system.

Another difference is how spread out the eye of the storm is, Burns said.

“The center of circulation is a tropical storm can be very, very small – maybe 10 to 20 miles wide,” Burns said. “But in a subtropical storm, that can be more than 100 miles wide.”

This makes subtropical storms larger by comparison but weaker since their energy is spread out.

This doesn’t mean subtropical storms should be overlooked or underestimated.

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Alberto’s standing wind speeds when it hits the Gulf shore Monday is expected to be around 60 mph. There’s a low chance that tornadoes can form along the outer regions of the storm, Channel 2 reported.

It’s also expected to rain a lot. Florida and the Gulf Coast is expected to get up to 15 inches of rain, and North Georgia could see up to 5 or 6 inches. 

Beach erosion and riptides are also expected along the coast, which can endanger swimmers, so the ocean should definitely be avoided until the storm dissipates.


And that’s all if it doesn’t develop into a stronger, tropical storm. Given the possibility, Tropical Storm Warnings have been issued for parts of Mississippi, Alabama and Florida. A Tropical Storm Watch was issued for Louisiana coastlines near New Orleans. 

A state of emergency was declared Saturday for Florida, Mississippi and Alabama.

Regardless of Alberto’s categorization, it shouldn’t be ignored and has the chance to threaten property and life.

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