What Is a Potential Tropical Cyclone?

Potential tropical cyclones allow advisories to be issued on systems that have yet to develop but pose a threat of bringing tropical-storm-force or hurricane-force winds to land areas within 48 hours.

This allows watches and/or warnings to be issued with more lead time.

June 2017's Potential Tropical Cyclone Two and Potential Tropical Cyclone Three went on to become Tropical Storm Bret and Tropical Storm Cindy, respectively.

They are treated like tropical depressions, named storms and hurricanes even though they haven't officially developed.

According to James Franklin, former branch chief of the hurricane specialist unit at the NHC, "the likelihood of tropical-storm-force land impacts would be at least as important a consideration as the likelihood of tropical cyclogenesis." 

Franklin described this update as an option for the NHC that will allow for more emphasis on impacts. The new option breaks down some of the barriers between certain categories and the ability to warn the public about potentially deadly impacts.  

Systems that have a chance of development anywhere in the Atlantic Basin will still be outlooked in the NHC's Tropical Weather Outlook product.

Those tropical disturbances, sometimes called invests, or areas of investigation, are given a forecast chance of formation for the next five days. This will still be tagged this season; however, systems that will likely impact land with a potentially deadly or damaging threat will be referred to as potential tropical cyclones.