The NHC classified the storm as a “preseason subtropical storm.” While there is a difference in the classification of storms – from extratropical, to subtropical, to tropical – they are all capable of threatening life and property.
Here’s a look at the characteristics of both subtropical and tropical systems.
A subtropical storm is basically a low-pressure system that is partially a winter-type storm and partially a tropical storm.
They are colder than tropical storms, meaning the core temperature is lower than a tropical storm’s core temperature. Warm water feeds tropical systems making them spin faster and become stronger.
There is a closed low-pressure center of circulation with the storms, just as with tropical storms, but the rains and wind are not near the center. Instead, thunderstorm activity and strong winds are miles (sometimes hundreds of miles) from the center of circulation. Think of the shape of a comma.
They are less likely to become hurricanes, though they can.
They are generally large storms.
Tropical storms are powered by very warm water, and are well-connected to the upper atmosphere. The warm water is drawn up into the system through the upper atmosphere and pushed down again as the cycle repeats, causing a heat pump effect that fuels the storm.
Tropical storms gain strength by thunderstorm activity around the eye, or center of circulation.
MIAMI, FL - MAY 24: Hurricane Specialist John Cangialosi (L) and Dennis Feltgen, the Communications and Public Affairs Officer, work at the National Hurricane Center as they look at a computer screen showing the first subtropical depression of the 2018 Atlantic hurricane season on May 24, 2018 in Miami, Florida. Subtropical Storm Alberto formed Friday in the Caribbean Sea. (Photo by Joe Raedle/Getty Images)