Here’s What a ‘Potential Tropical Cyclone’ Means
The National Weather Center has added the term ‘potential tropical cyclone’ to its arsenal…and there’s a good reason for it.
A new phrase, a “potential tropical cyclone,” has emerged during this year’s hurricane season and it’s causing a bit of confusion.
As Hurricane Harvey made its assault on the Texas coast, meteorologists were also watching a system off the Carolina coast they initially expected to become Tropical Storm Irma.
That system never developed, I’m told, because of atmospheric conditions that didn’t allow it to organize well enough.
In the past, we’d hear more about “Invests,” which are areas being investigated for possible tropical development. Some meteorological friends of mine say that term still exists and is still being used.
But the potential tropical cyclone is a special circumstance that allows forecasters to get the word out more effectively. When an “invest” is approaching land, government regulations won’t allow certain advisories, like a Tropical Storm Watch, to be issued until the invest actually becomes a tropical storm.
A system that develops the rotating, “cyclonic” conditions and that has maximum sustained winds of at least 39 miles per hour, becomes a tropical storm and receives a name.
Tropical depressions, tropical storms and hurricanes are all cyclones.
But earlier this week, parts of the South Carolina and North Carolina coastlines were suddenly under a Tropical Storm Watch — meaning tropical storm conditions were expected within about 36 hours — when there was no tropical storm.
What was nearing the coastline, however, was “Potential Tropical Cyclone 10.” And with that change in nomenclature, authorities were able to declare a tropical storm watch ahead of time to alert residents that the potential danger was there.
It’s a clever way to bypass rules and red tape so that when a storm is believed to be imminent, the word about the potential danger can be sent out that much sooner.
It’s worth noting that while the system off the coastline did not officially become Tropical Storm Irma, we do now have a storm by that name. It’s a new system that formed off the coast of Africa and rapidly formed into a tropical storm and could be a hurricane today or tomorrow. As of 5 a.m., Thursday, its maximum sustained winds were already up to 70 miles per hour. If that speed increases to 74 miles per hour, we’ll have a Category 1 hurricane.
Since the system that lingered along the Carolina coast didn’t develop, there’s always the fear that people won’t take such phrases seriously the next time.
People seem too quick these days to dismiss warnings designed to make them aware of the potential impact even though they often say they’d rather know of potential problems with as much notice as possible.
But the counties affected did have heavy amounts of rain and some flooding as if a tropical storm had actually developed. Thanks to the new policy, alerts about the potential for such conditions was sent out more emphatically and sooner than would have been possible otherwise.
Though the terminology may sound a bit confusing, we can at least hope it will make people pay attention and use the extra notice to safeguard their families and belongings.