What's the difference between subtropical storm and tropical storm?
Tropical storms and hurricanes are familiar terms to everyone who keeps a wary eye on the tropics, but what about subtropical storms?
What is a subtropical storm and how is it different from a tropical storm?
There are a lot of similarities between the two and for residents on the ground, the same conditions can be expected.
Summary of differences between subtropical and tropical storms
First, how they are the same:
Both need warm water near 80 degrees to develop.
Both form out of low-pressure weather systems over the ocean.
Both have well-defined centers and a closed center of circulation.
They both bring possible similar impacts on land, including rain, high winds, storm surge, dangerous surf and potential flooding.
Both have maximum sustained surface wind speeds of at least 39 mph.
However, subtropical storms:
Have the characteristics of both a tropical storm and a non-tropical weather system.
Generally are more disorganized than tropical storms.
Have cooler upper-level temperatures in their core.
Can still be dangerous and can develop into tropical storms or, more rarely, into hurricanes.
Have a much larger wind field and the strongest winds and thunderstorms are much farther from the center. In a tropical storm, the strongest winds are close to the center.
Look more ragged and asymmetrical than tropical storms. There may be a lot of showers on the south and east sides but virtually nothing on the west side.
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Forecasters describe subtropical storms as a 'hybrid' storm
Meteorologists divide storms, or cyclones, into two general types: extratropical storms and tropical storms.
A subtropical storm is what's known to forecasters as a "hybrid" storm, a meteorological mix of a tropical and extratropical storm.
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Should people in the path of a subtropical storm be less concerned?
Forecasters warn that, for people on the ground, there is little difference between a tropical and subtropical storm. Both bring rain, high winds, dangerous surf and potential flooding.
"The wind speeds of tropical and subtropical systems are the same, so we are telling folks not to focus on the wording because the impacts will be the same,” said Morgan Barry, a meteorologist with the National Weather Service.
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Can a subtropical storm become a hurricane?
If the subtropical storm remains over warm water for several days, it may eventually become fully tropical, and be called a tropical storm. This happens when thunderstorms start building close to the center of circulation, and the strongest winds and rain are no longer in a band far from the center.
Once that happens, further intensification into a hurricane is possible.
In 2018, seven storms were designated as subtropical for at least part of their existence.
Subtropical storms in the Atlantic basin
The NHC began naming subtropical storms in 2002.
Between 1968 and 2001, subtropical storms were given numbers.
Before 1968, subtropical storms were never classified as such, but were sometimes called "Unnamed storm."
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This article originally appeared on Fort Myers News-Press: Subtropical storm vs. tropical storm: What's the difference, impacts?
