Same storm, different names: How Invest 97L could graduate to Tropical Storm Debby
It is an area of low pressure, thunderstorms and wind that flows from the Caribbean Sea over Cuba to the Gulf of Mexico and towards FloridaBut by the time it disappears, weather experts may have given it as many as five different names.
First it was Invest 97L, then it was Potential Tropical Cyclone Four. Friday night when it strengthened it became Tropical Depression Four. It is expected to become Tropical Storm Debby on Saturday and could intensify into Hurricane Debby on Sunday or Monday.
The different names are used to classify the intensity of a storm in the Atlantic and eastern and central Pacific. Most storms begin as an area of intense thunderstorms before developing the cyclonic rotation of winds that travel in a circle, sometimes around a clear eye.
In the Northern Hemisphere, the winds blow counterclockwise, while in the Southern Hemisphere they blow clockwise.
Before the National Hurricane Center issued its first advisory on the system Friday, it was designated “Invest 97L.” Jack Beven, senior hurricane specialist at the National Hurricane Center, said “invest,” short for investigation, is primarily an internal designation used to indicate a tropical wave or area of disturbed weather that meteorologists want to keep an eye on.
Beven said an investment doesn’t necessarily mean the system is more dangerous or on the verge of becoming a tropical cyclone, but it is a status marker that indicates the disturbance has reached a point where the agency can monitor it.
“It’s a bit of an indication that the system has become more interesting,” Beven said.
The weather bureau uses the letter “L” to indicate its location in the Atlantic Ocean, Beven said. The bureau alternates between the numbers 90 and 99 to name and track the systems.
On Friday, the National Hurricane Center was confident that Invest 97L would develop into something more serious.
The agency’s initial advisory on Friday indicated the system was strengthening, designating it Potential Tropical Cyclone Four. The storm became a tropical depression on Friday evening, indicating it was organizing into a cyclone but still had 1-minute sustained winds of less than 39 mph (62 kilometers) per hour.
Forecasters expect the storm to continue to strengthen. Once they judge it has passed the 39 mph mark, it will be given a name: Tropical Storm Debby.
Like a tropical storm When winds reach 74 mph (119 km/h), it is reclassified as a hurricane.
In the Atlantic basin, hurricanes are classified by their wind speed on a scale of 1 to 5, with 1 being weakest and 5 being strongest. However, wind strength tells us nothing about how much tidal storm surge a hurricane can push toward coastal areas, or how much rain it can bring.
Some of the rainiest tropical systems don’t even make it to hurricane status, such as Tropical Storm Allison of 2001, which billions of dollars in flood damage in and around Houston.
Weather forecasters began naming storms after World War II to better communicate the threat to the public. Before that, storms were usually given names after the fact, and they could vary — such as the Galveston Hurricane of 1900, the Labor Day Hurricane of 1935, or the Great New England Hurricane of 1938.
Initially, meteorologists named hurricanes only after women, but in 1979, men’s names were also used. The World Meteorological Organization takes another list of names each year for each major tropical cyclone region worldwide. The Atlantic names are used every six years.
No. Intense tropical cyclones in the western Pacific and near Japan and Asia are called typhoons. Those around India are called cyclonic storms. And around Australia and in the southwestern Pacific they are called tropical cyclones.
There are some similarities in the intensity scales. For example, the wind threshold to become a hurricane in the Gulf of Mexico is the same as to become a typhoon in Asia or a very severe cyclonic storm near India.