2019 Atlantic hurricane season (Hypothetical/actual)

The 2019 Atlantic hurricane season was the fourth in a row of above average Atlantic hurricane seasons, only slightly above average, with 14 named storms, 6 hurricanes, and 3 major hurricanes. The season costed a total of 37.6 billion USD. The season officially began on June 1, 2019, and ended on November 30, 2019. These dates historically describe the period each year when most tropical cyclones form in the Atlantic basin and are adopted by convention. However, tropical cyclogenesis is possible at any time of the year, as demonstrated by the formation of Subtropical Storm Andrea on May 20, and the formation of Tropical Storm Nestor on December 17, marking the record fifth year in a row where a tropical or subtropical cyclone developed before the official start of the season, breaking the previous record of four years set in 1951–1954, and the first in seven years to form after the offical end of the season. This was also the second year in a row in which no storms formed during the month of June. The season was the second slowest-starting Atlantic hurricane season of the 21st century, as the third named storm (Chantal) formed on August 21; the previous second latest formation date was Tropical Storm Chantal of 2001, which formed on August 14. The slowest-starting Atlantic hurricane season of the 21st century is the 2014 Atlantic hurricane season, and the latest formation date which corresponds to the two storms mentioned previously was Hurricane Cristobal, which formed on August 23 in that year. This was the record fourth season with atleast one Category 5 hurricane forming (Hurricane Dorian) including Matthew in 2016, Irma and Maria in 2017, and Michael in 2018.

Seasonal forecasts
Ahead of and during the season, several national meteorological services and scientific agencies forecast how many named storms, hurricanes, and major hurricanes (Category 3 or higher on the Saffir–Simpson scale) will form during a season and/or how many tropical cyclones will affect a particular country. These agencies include the Tropical Storm Risk (TSR) Consortium of University College London, the National Oceanic and Atmospheric Administration (NOAA) and Colorado State University (CSU). The forecasts include weekly and monthly changes in significant factors that help determine the number of tropical storms, hurricanes, and major hurricanes within a particular year. Some of these forecasts also take into consideration what happened in previous seasons and the state of the El Niño–Southern Oscillation (ENSO). On average, an Atlantic hurricane season between 1981 and 2010 contained twelve tropical storms, six hurricanes, and three major hurricanes, with an accumulated cyclone energy (ACE) index of between 66 and 103 units.

Subtropical Storm Andrea
On May 17, 2019, the National Hurricane Center (NHC) began forecasting the formation of an area of low pressure south of Bermuda, which had the potential to later develop into a tropical or subtropical cyclone.[18] On the following day, a large and elongated area of clouds and thunderstorms developed well to the east of the Bahamas. The disturbance gradually organized over the next two days as it moved westward and then northward, though it still lacked a well-defined circulation. However, an Air Force reconnaissance flight late on May 20 revealed that the storm had a well-defined center with winds reaching gale force, due to being involved with an upper-level low to its west, leading to the classification of the system as Subtropical Storm Andrea at 22:30 UTC that day. Soon afterward, Andrea reached its peak intensity. The nascent storm did not last very long, as the storm encountered dry air from the south, as well as southerly wind shear. These hostile conditions caused Andrea's convection to dissipate, and the storm degenerated into a remnant low early on the next day.

Hurricane Barry
A trough of low pressure in the Midwest began moving south, towards the Gulf of Mexico. On July 6, the NHC began monitoring it over the Tennessee Valley and forecast it to move southwards, emerge into the northeastern Gulf of Mexico, and potentially develop into a tropical cyclone within several days. Over the next few days, the trough drifted southward, due to the steering influence of a ridge of high pressure, and the trough developed a broad area of low pressure on July 9, shortly before the system entered the Gulf of Mexico from the Florida big bend. The low-pressure system, while still lacking a well-defined center of circulation, became a little better defined on the following day. As the system had a high potential of producing tropical storm conditions and storm surge along the coast of Louisiana within the next couple of days, the NHC initiated advisories on Potential Tropical Cyclone Two at 15:00 UTC on July 10. The system subsequently organized into a tropical storm at 15:00 UTC on July 11. The system slowly moved westward, affecting the U.S. Gulf Coast. The system finally strengthened into a hurricane at 15:00 UTC on July 13 making it the first of the season.[31]However, three hours later, at 18:00 UTC, wind shear began to increase, causing the system to begin weakening. Around that time, Barry made landfall on Intracoastal City, Louisiana, as a Category 1 hurricane, before weakening to tropical storm status afterward, causing extensive damage to Lafayette, Lake Charles, and Baton Rouge. Barry gradually weakened while slowly moving inland, weakening into a tropical depression at 21:00 UTC on July 14.[33]At 21:00 UTC on July 15, Barry weakened into a remnant low over northern Arkansas. During the next several days, Barry's remnant moved eastward while gradually weakening, before being absorbed into another frontal system off the coast of New Jersey on July 19. Barry caused one fatality, with a man killed by a rip current off the coast of the Florida Panhandle on July 15. Damage from the storm is currently at >$600 million (2019 USD).

Tropical Depression Three
Early on July 21, the NHC began monitoring a tropical wave located about 300 miles east of the Bahamas for potential tropical cyclone development. Despite the disturbance having a low chance of tropical cyclone formation, rapid organization ensued on the following day, with a closed low-level circulation developing, as deep convection increased in association with the small low-pressure system. Subsequently, at 21:00 UTC on July 22, the NHC classified the system as Tropical Depression Three. However, deep convection associated with the tropical depression soon dissipated, and although convection redeveloped early on July 23, the cyclone remained disorganized. An Air Force reconnaissance aircraft investigating the system that morning found no evidence of a surface circulation, and at 15:00 UTC that day, the tropical depression degenerated into a trough of low pressure while located off the east coast of Florida. The storm's remnants continued to move northward, before being absorbed by a frontal system several hours later, early on the next day. The impacts were very minimal with the storm, with only 1-3 inches of rainfall in South Florida and The Bahamas.

Tropical Storm Chantal
Late on August 16, the NHC began monitoring a surface trough located over northeastern Florida for tropical cyclone development. A small low pressure system developed in association with the trough as it moved northeastward along the East Coast of the United States, although the system's proximity to the coast prevented significant development at that time. Although environmental conditions were not forecast to favor significant development, thunderstorm activity associated with the system became better organized on August 20, and the circulation became better defined. By 03:00 UTC on August 21, the system had developed a well-defined surface circulation and was producing tropical storm-force winds to the south of its center, resulting in the classification of Tropical Storm Chantal over the far northern Atlantic. Chantal lasted 24 hours as a tropical storm before weakening into a tropical depression and dissipating over open waters a day later.

Hurricane Dorian
Early on August 23rd, a low-pressure system formed in the open Atlantic Ocean, between the Cape Verde Islands and the Lesser Antilles on August 23. The system quickly organized overnight and on August 24, it was classified as a tropical depression several hundred miles east-southeast of Barbados. That same day, it achieved tropical storm status and was given the name Dorian. At first, the system remained small and weak; however, on August 25, it began to strengthen and expand in size. At 1800 UTC on August 28, Dorian reached hurricane status at landfall on the US Virgin Islands. A weather station reported winds of 82 mph (132 km/h) and a gust of 111 mph (179 km/h). There was some dry air still in the system after moving to the north. Eventually, the dry air was expelled from the system, which promoted rapid intensification; Dorian reached Category 3 major hurricane strength on August 30. Rapid intensification continued thereafter, and Dorian reached Category 4 intensity that night, having intensified from a Category 2 hurricane to a Category 4 hurricane in just over 9 hours. Dorian strengthened into a Category 5 hurricane on September 1. This made 2019 the record fourth consecutive year to feature a Category 5 hurricane, surpassing the three year period 2003–2005. The system continued to strengthen rapidly throughout the day, becoming the strongest hurricane to impact the northwestern Bahamas since modern records began. Dorian made landfall on Elbow Cay at 16:40 UTC on later that day at peak intensity with 1-minute sustained winds of 185 mph (295 km/h); the storm continued strengthening during landfall, with its minimum central pressure bottoming out at 910 millibars (26.87 inHg) a few hours later. At 02:00 UTC on the next day, Dorian made landfall on Grand Bahama near the same intensity, with the same sustained wind speed. A few hours later, Dorian stalled just north of Grand Bahama island, as the Bermuda High situated to the northeast of the storm collapsed. Around the same time, the combination of an eyewall replacement cycle and upwelling of cold water caused Dorian to begin weakening.[64] Hurricane Dorian weakened to a Category 2 storm on September 3, before beginning to move northwestward at 15:00 UTC, parallel to the east coast of Florida; Dorian's wind field expanded during this time. At 06:00 UTC on September 5, Dorian moved over the warm waters of the Gulf Stream and completed its eyewall replacement cycle, reintensifying into a Category 3 hurricane. However, several hours later, high wind shear began to take its toll, causing the storm to weaken to a Category 2 hurricane, and later to Category 1. On September 7, Dorian transitioned into an extratropical cyclone. At 18:00 UTC that day, Dorian intensified into a Category 2-equivalent extratropical storm, due to baroclinic forcing.[68] Several hours later, the system transitioned to an Extratropical cyclone as it made landfall in Sambro Creek, Nova Scotia at 7:05 p.m. EDT on September 7.

Damage from the storm is currently estimated at $7 billion in the Bahamas by Bloomberg L.P.; the death toll from Dorian is currently estimated at 52 deaths (47 direct and 5 indirect deaths).

Tropical Storm Erin
Early on August 21, the NHC started to monitor a disturbance over the Bahamas for potential development. The disturbance continued northwestward, and briefly moved over Florida. This weakened the system, and then it re-emerged over the Atlantic. A few days later, after having moved northeastward away from Florida, the system was still poorly organized, but a closed circulation prompted the NHC to initiate advisories on Tropical Depression Six at 2100 UTC August 26. Due to northwesterly wind shear, convection was displaced to the south-east quadrant of the center. Due to this, the system struggled to strengthen for a while. However, the center soon moved closer to the convection, which then began to envelop the center. This prompted the National Hurricane Center to upgrade the depression to Tropical Storm Erin. Wind shear displaced the center from the convection a few hours later, weakening the system back to a tropical depression as a result. A day later, the system transitioned into an extratropical cyclone, and the NHC discontinued advisories on the system.

In Nova Scotia, precipitation from the remnants of Erin was higher than for all of July and August combined before the storm. According to the Meteorological Service of Canada, the Annapolis Valley and the Bay of Fundy region received the most precipitation with a maximum of 162 mm at Parrsboro and 127 mm at Greenwood. Elsewhere, 53 mm fell in Halifax, 79 mm in Yarmouth, and at the peak of precipitation, several stations reported rates greater than 30 mm per hour, resulting in increased runoff, causing flash floods and the wash out of roads.

On the New Brunswick side, rain affected the southern part of the province with maximums of 56 mm in Fredericton, 50 mm in Moncton and 44 mm in Saint John. In Prince Edward Island, accumulations ranged from 30 to 60 mm with a maximum of 66 mm in Summerside. However, volunteers' weather stations reported up to 111 mm at Jolicure/Sackville in New Brunswick and up to 95 mm at Borden-Carleton on Prince Edward Island, along the same axis as the Nova Scotia maximums. In Quebec, the regions near the Gulf of St. Lawrence also received about 50 mm of rain.

A broad area of low pressure began to be monitored over the southeast Gulf of Mexico on August 31 for potential tropical cyclone development. The system gradually developed while moving slowly westward. On September 2, the satellite imagery showed that the surface circulation became better defined, and that the system was more concentrated.

On September 3, the disturbance was designated Potential Tropical Cyclone Seven, with a virtually certain chance of tropical cyclone development. Six hours later, the system organized into the seventh tropical depression of the season and rapidly developed into Tropical Storm Fernand. Fernand made landfall in Mexico on September 4, bringing heavy rainfall and storm surge. Heavy rainfall was also recorded in South Texas. The storm weakened rapidly and dissipated within 12 hours of landfall.