The 2017 Atlantic hurricane season has featured the first major hurricane to make landfall in the United States since 2005, as well as the most rainfall for any Atlantic tropical cyclone in the United States and the fifth highest rainfall total for a tropical cyclone in the Atlantic basin; 51.88 in (1,318 mm) from Hurricane Harvey in Texas. It is also the third costliest season on record with 58 billion dollars of damages. It is an ongoing event in the annual formation of tropical cyclones in the Atlantic basin. The season officially began on June 1 and will end on November 30. These dates historically describe the period of year when most tropical cyclones form in the Atlantic basin and are adopted by convention. However, as shown by Tropical Storm Arlene in April, the formation of tropical cyclones is possible at any time of the year.
For the third consecutive year activity began early, with the formation of Tropical Storm Arlene on April 19, nearly a month and a half before the official start of the season. It is only the second named storm on record to exist in the month of April, with the first being Ana in 2003, as well as the strongest overall for the month of April. In mid-June, Tropical Storm Bret struck the island of Trinidad, which is rarely impacted by tropical cyclones due to its low latitude. Tropical Storm Cindy struck the state of Louisiana a few days later, becoming the first tropical cyclone to strike the state since Hurricane Isaac in 2012. In late August, Hurricane Harvey became the first major hurricane to make landfall in the United States since Wilma in 2005.
Beginning this year, the National Hurricane Center has the option 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, including track forecasts and cyclone watches and warnings, as advisories 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. Wikipedia