|This swirl of clouds way out over the Atlantic Ocean|
could become a subtropical storm today. If it does,
it would be named Arlene.
Wednesday, April 19, 2017
Rare April Subtropical Storm Might Be Forming In Atlantic Ocean
A rare - for this time of year anyway - subtropical storm might be forming way out over the Atlantic Ocean today.
Subtropical storms are hybrids between pure tropical storms and hurricanes, which have warm cores.
Most other kinds of storms have cold air at their cores, and have cold and warm fronts attached to them.
Subtropical storms have elements of regular storms, such as a cold pocket of air within them.
However, like tropical storms, subtropical storms have no cold or warm fronts, and thunderstorms spinning around an often cloud-free center.
Subtropical storms are given names, just like tropical storms, and would show up on a list of any year's tropical storms or hurricanes if they form.
Tropical or subtropical storms in the Atlantic Ocean are very rare in April, when ocean tempeatures tend to be coolest. Most of these storms need warm water to survive.
The possible subtropical storm now is forming way out there in an expanse of ocean between Bermuda and the Azores. The National Hurricane Center gives it a 70 percent chance of becoming a subtropical storm.
If it does form, it will be named Arlene.
Deciding whether a storm like this one is subtropical or not is pretty subjective. I've seen some pretty spirited arguments on Twitter today from weather geeks as to whether this one qualifies or not.
If it's decided a subtropical storm forms today, it won't last long. Forecasters expect it to be swallowed up by a larger regular storm on Thursday.
Subtropical storms can grow and change into purely tropical storms, with totally warm cores and no cold air anywhere near them.
The only time this has been known to happen was with the already-mentioned Ana in 1993.
If a subtropical storm forms today, it is very unlikely to become purely tropical.