Potential Tropical Cyclone Ten was a damaging storm that was the tenth tropical disturbance designated by the National Hurricane Center (NHC) during the 2017 Atlantic hurricane season. The disturbance was deemed to have a very high chance of becoming a tropical cyclone while posing a threat to populated areas and was designated a "Potential Tropical Cyclone". The storm caused flooding and brought tropical storm-force winds to parts of the Southeastern United States and the Mid-Atlantic states, particularly Florida and the Carolinas, before going on to affect parts of Atlantic Canada. Potential Tropical Cyclone Ten was the tenth storm that had advisories issued on it by the NHC in 2017, and the only such system that failed to fully develop into a tropical cyclone during that Atlantic hurricane season. Potential Tropical Cyclone Ten originated from a tropical wave that moved off the coast of West Africa on August 13. The disturbance slowly tracked its way westward across the Atlantic Ocean, before reaching Florida in late August. The disturbance came close to developing into a tropical storm while it was situated off the coast of the Carolinas; however, strong wind shear and outflow from Hurricane Harvey prevented the storm from organizing into a tropical cyclone. The system transitioned into an extratropical cyclone instead, and became a strong hurricane-force low to the south of Newfoundland, before being absorbed by another extratropical system near Iceland on September 3.
The storm caused flooding across Florida, especially around Fort Myers and other areas in southwestern Florida, forcing the evacuation of more than 200 people. The disturbance dropped a maximum total of rainfall in excess of of rain in Ten Mile Canal and Six Mile Cypress Slough Preserve, in southwestern Florida, in addition to of rain in the western parts of Fort Myers. The flooding was the worst seen in western Florida in at least 20 years. Overall, the storm killed two people and caused more than $1.923 million (2017 USD) in damages. Less than two weeks after the storm, Hurricane Irma made landfall in southwestern Florida, which further compounded the damage in the region.
Background
Beginning in 2017, the National Hurricane Center (NHC) decided to issue advisories, and thus allow watches and warnings to be issued on disturbances that are not yet tropical cyclones but have a high chance to become one, and are expected to bring tropical storm or hurricane conditions to landmasses within 48 hours. Such systems are termed "Potential Tropical Cyclones". Advisories on these storms contain the same content as typical tropical cyclone advisories, including track forecasts, and cyclone watches and warnings, similar to advisories that the NHC issues on active tropical cyclones. This was first demonstrated on June 18 with the designation of Potential Tropical Cyclone Two, which later developed into Tropical Storm Bret, east-southeast of the Windward Islands. In addition, the numbering that a potential tropical cyclone receives would be retained for the rest of the hurricane season, meaning that the next tropical system or disturbance would be designated with the following number, even though potential tropical cyclones are not treated as tropical cyclones. This was first demonstrated with Potential Tropical Cyclone Ten, which failed to develop into a tropical cyclone. After that storm's formation and dissipation, one of the following tropical systems, which would eventually become Hurricane Katia, was designated as "Tropical Depression Thirteen", even though the Atlantic hurricane season had a total of only 12 tropical cyclones at that point. Potential Tropical Cyclone Ten was the first system so designated not to become an organize as a tropical cyclone, and as of 2022, it was one of only three disturbances not to have developed, with the others being Potential Tropical Cyclone Seventeen-E during the 2019 Pacific hurricane season and Potential Tropical Cyclone Four during the 2022 Atlantic hurricane season.