Every year when hurricane season approaches, you’ll start to see tropical talk centered around something called an “invest.” Invest is short for “investigation” and it refers to a weather feature that the National Hurricane Center (NHC) is investigating. It should be noted that it is NOT necessarily an area that is expected to develop into a tropical system. It’s simply an area being investigated for any number of reasons.
In their glossary, the NHC defines an invest as: “a weather system for which the NHC is interested in collecting specialized data sets and/or running model guidance. Once a system has been designated as an invest, data collection and processing is initiated on a number of government and academic websites.”
Dan Brown, Warning Coordination Meteorologist at the National Hurricane Center, told me that there are no set standards for initializing an invest. It’s really a procedural thing within the Hurricane Center and wasn’t originally meant for public consumption. Sometimes an invest is named simply to test the models and products. Sometimes no skillful computer models are even run on a invest. There are no latitude/longitude coordinates plotted. Part of the NHC glossary definition says: “The designation of a system as an invest does not correspond to any particular likelihood of development of the system into a tropical cyclone.”
A good meteorologist may talk about an area of potential tropical development long before an invest is triggered by NHC. Conversely, you may not hear your favorite TV meteorologist say a word about an invest, even though you’ve seen it posted somewhere online.
Areas of investigation in the Atlantic Basin are given numbers from 90-99. The first invest of a season will be named Invest 90-L. The “L” means it’s in the Atlantic (“A” is assigned to invests in the Arabian Sea and “E” is for areas in the Eastern Pacific Ocean). The numbers repeat, which means the second invest of a season will get the name Invest 91-L. After Invest 99-L, the numbers recycle back to 90.
The purpose of the numbers is basically just to name which disturbance is being tracked since there is usually more than one happening at the same time.