A subtropical cyclone is a weather system that has some characteristics of both tropical and extratropical cyclones.
The 2003 Atlantic hurricane season was a very active season with tropical cyclogenesis occurring before and after the official bounds of the season—the first such occurrence since the 1970 season. The season produced 21 tropical cyclones, of which 16 developed into named storms; seven of those attained hurricane status, of which three reached major hurricane status. The strongest hurricane of the season was Hurricane Isabel, which reached Category 5 status on the Saffir–Simpson hurricane scale northeast of the Lesser Antilles; Isabel later struck North Carolina as a Category 2 hurricane, causing $3.6 billion in damage and a total of 51 deaths across the Mid-Atlantic region of the United States.
The 2002 Atlantic hurricane season was a near-average Atlantic hurricane season. It officially started on June 1, 2002, and ended on November 30, dates which conventionally limit the period of each year when most tropical cyclones develop in the Atlantic Ocean. The season produced fourteen tropical cyclones, of which twelve developed into named storms; four became hurricanes, and two attained major hurricane status. While the season's first cyclone did not develop until July 14, activity quickly picked up: eight storms developed in the month of September. It ended early however, with no tropical storms forming after October 6—a rare occurrence caused partly by El Niño conditions. The most intense hurricane of the season was Hurricane Isidore, a Category 3 storm with a minimum central pressure of 934 mbar; however, Hurricane Lili, with a minimum pressure of 938 mbar, attained higher winds and peaked at Category 4.
The 2000 Atlantic hurricane season was a fairly active hurricane season, but featured the latest first named storm in a hurricane season since 1992. The hurricane season officially began on June 1, and ended on November 30. It was slightly above average due to a La Niña weather pattern although most of the storms were weak. It was also the only season to have two of the storms affect Ireland. The first cyclone, Tropical Depression One, developed in the southern Gulf of Mexico on June 7 and dissipated after an uneventful duration. However, it would be almost two months before the first named storm, Alberto, formed near Cape Verde; Alberto also dissipated with no effects on land. Several other tropical cyclones—Tropical Depression Two, Tropical Depression Four, Chris, Ernesto, Nadine, and an unnamed subtropical storm—did not impact land. Five additional storms—Tropical Depression Nine, Florence, Isaac, Joyce, and Leslie—minimally affected land areas.
The 1967 Atlantic hurricane season was an active Atlantic hurricane season overall, producing 13 nameable storms, of which 6 strengthened into hurricanes. The season officially began on June 1, 1967, and lasted until November 30, 1967. These dates, adopted by convention, historically describe the period in each year when most tropical cyclogenesis occurs in the Atlantic Ocean. The season's first system, Tropical Depression One, formed on June 10, and the last, Tropical Storm Heidi, lost tropical characteristics on November 2.
The 1978 Atlantic hurricane season was a slightly above average hurricane season in terms of number of named storms. Eleven tropical cyclones were named in all, and five of these became hurricanes; two of the five became a major hurricane. This was also the last Atlantic hurricane season to use an all-female naming list. The season officially began on June 1, 1978, and ended on November 30, 1978. These dates, adopted by convention, denote the period in each year when most tropical cyclogenesis occurs in the Atlantic basin. However, the formation of subtropical or tropical cyclones is possible at any time of the year, as shown by the formation of an unnamed subtropical storm on January 18.
The 1984 Atlantic hurricane season was the most active since 1971, though the season was below average in hurricanes and major hurricanes. It officially began on June 1, 1984, and lasted until November 30, 1984. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin. The 1984 season was an active one in terms of named storms, but most of them were weak and stayed at sea. Most of the cyclones tracked through the northwest subtropical Atlantic west of the 50th meridian to near the Eastern coast of the United States between mid-August and early October. The most damaging storm was Hurricane Klaus, which caused $152 million (1984 dollars) in damage in Puerto Rico. Hurricane Diana was the first hurricane to strike a nuclear power plant without incident; it was also the first major hurricane to strike the U.S. East Coast in nearly 20 years. Also of note was Hurricane Lili, which lasted well after the official end of the season. It was downgraded from a named storm on December 24. Damage overall from the tropical cyclones in 1984 totaled $228.7 million. Unusually, no hurricanes developed from tropical waves in 1984, which usually are the source of the strongest storms in an Atlantic hurricane season.
The 1991 Atlantic hurricane season was the first season since 1984 in which no hurricanes developed from tropical waves, which are the source for most North Atlantic tropical cyclones. The hurricane season officially began on June 1, and ended on November 30. It was the least active in four years due to higher than usual wind shear across the Atlantic Ocean. The first storm, Ana, developed on July 2 off the southeast United States and dissipated without causing significant effects. Two other tropical storms in the season – Danny and Erika – did not significantly affect land. Danny dissipated east of the Lesser Antilles, and Erika passed through the Azores before becoming extratropical. In addition, there were four non-developing tropical depressions. The second depression of the season struck Mexico with significant accompanying rains.
The 2006 Atlantic hurricane season was the least active in the basin since 1997, with nine named storms as well as an additional unnamed tropical storm identified by the National Hurricane Center. 2006 was the first season since 2001 in which no hurricanes made landfall in the United States, and was the first since 1994 in which no tropical cyclones formed during October. Following the intense activity of 2003, 2004, and 2005, forecasters predicted that the 2006 season would be only slightly less active. Instead, it turned out to be a below average season, as activity was slowed by a rapidly forming moderate El Niño event, the presence of the Saharan Air Layer over the tropical Atlantic, and the steady presence of a robust secondary high-pressure area to the Azores High centered on Bermuda. There were no tropical cyclones after October 2.
Subtropical Storm Nicole was the first subtropical storm to receive a name using the standard hurricane name list that did not become a tropical cyclone. The fifteenth tropical or subtropical cyclone and fourteenth named storm of the 2004 Atlantic hurricane season, Nicole developed on October 10 near Bermuda from a broad surface low that developed as a result of the interaction between an upper level trough and a decaying cold front. The storm turned to the northeast, passing close to Bermuda as it intensified to reach peak winds of 50 mph (80 km/h) on October 11. Deep convection developed near the center of the system as it attempted to become a fully tropical cyclone. However, it failed to do so and was absorbed by an extratropical cyclone late on October 11.
Hurricane Ioke, also referred to as Typhoon Ioke, was a record-breaking, long-lived and extremely powerful storm that traversed the Pacific for 17 days, reaching the equivalent of Category 5 status on the Saffir–Simpson hurricane scale on three different occasions. It was the most intense hurricane ever recorded in the Central Pacific, as well as the fifth-most intense Pacific hurricane on record, tied with 1973's Hurricane Ava. It also generated the most accumulated cyclone energy for a single storm, until Cyclone Freddy surpassed its record in 2023. Ioke was the ninth named storm, fifth hurricane, and third major hurricane of the active 2006 Pacific hurricane season.
Hurricane Karen was a hurricane of non-tropical origin that formed in October of the 2001 Atlantic hurricane season. It developed out of the interaction between a cold front and an upper level trough on October 10 located to the south of Bermuda, and quickly strengthened as an extratropical storm. The storm passed near Bermuda on October 12, producing hurricane-force winds on the island. It then organized, becoming a subtropical cyclone on October 12 and a tropical cyclone on October 13. Karen strengthened to reach 80 mph (130 km/h) winds as a Category 1 hurricane on the Saffir-Simpson Hurricane Scale, and after weakening over cooler waters, it made landfall on Nova Scotia as a tropical storm. It quickly became extratropical.
The 2005 Azores subtropical storm was the 19th nameable storm and only subtropical storm of the extremely active 2005 Atlantic hurricane season. It was not named by the National Hurricane Center as it was operationally classified as an extratropical low. It developed in the eastern Atlantic Ocean, an unusual region for late-season tropical cyclogenesis. Nonetheless, the system was able to generate a well-defined centre convecting around a warm core on 4 October. The system was short-lived, crossing over the Azores later on 4 October before becoming extratropical again on 5 October. No damages or fatalities were reported during that time. Its remnants were soon absorbed into a cold front. That system went on to become Hurricane Vince, which affected the Iberian Peninsula.
Hurricane Erin was the longest-lived hurricane in the 2001 Atlantic hurricane season. The sixth tropical depression, fifth tropical storm, and first hurricane of the season, Erin developed from a tropical wave on September 1. After strengthening to a 60 mph (97 km/h) tropical storm as it moved to the west-northwest, wind shear weakened Erin and caused it to degenerate into a remnant low on September 5. The remnants re-organized into a tropical depression the next day, and Erin strengthened into a hurricane on September 9 while moving northwestward. This was the latest date for the first hurricane of the season since Hurricane Diana on September 10, 1984. Erin quickly intensified and reached peak winds of 120 mph (190 km/h) later on September 9. At its closest approach, Erin passed 105 miles (169 km) east-northeast of Bermuda near peak intensity, and subsequently weakened as it turned to the east. A trough turned Erin to the northeast, and after passing just east of Cape Race, Newfoundland it became extratropical on September 15. The extratropical remnant continued northeastward and was absorbed into another extratropical storm near Greenland on September 17.
Tropical Storm Chantal was a short-lived tropical storm that affected Bermuda in its formative stages and caused flooding and gusty winds in Newfoundland while extratropical. The third named storm of the 2007 Atlantic hurricane season, Chantal developed on July 31 from non-tropical origins between Bermuda and Cape Cod, and with favorable conditions, the storm rapidly attained peak winds of 50 mph (80 km/h). The storm accelerated northeastward over an area of progressively colder water temperatures, and after a decrease in convection the National Hurricane Center ceased issuing advisories as Chantal began undergoing extratropical transition early on August 1. Shortly thereafter, the extratropical remnant crossed over southeastern Newfoundland before tracking into the open waters of the north Atlantic Ocean. Prior to forming, the storm dropped moderate rainfall on Bermuda. Subsequent to becoming extratropical, the remnants of Chantal produced gusty winds and heavy precipitation across the Avalon Peninsula of Newfoundland, causing flooding and wind damage; insured damage totaled $25 million.
The 2006 Pacific hurricane season was the first above-average season since 1997 which produced twenty-five tropical cyclones, with nineteen named storms, though most were rather weak and short-lived. There were eleven hurricanes, of which six became major hurricanes. Following the inactivity of the previous seasons, forecasters predicted that season would be only slightly above active. It was also the first time since 2003 in which one cyclone of at least tropical storm intensity made landfall. The season officially began on May 15 in the East Pacific Ocean, and on June 1 in the Central Pacific; they ended on November 30. These dates conventionally delimit the period of each year when most tropical cyclones form in the Pacific basin. However, the formation of tropical cyclones is possible at any time of the year.
Tropical Storm Laura was a large but short-lived tropical cyclone that developed over the north-central Atlantic Ocean in late September during the 2008 Atlantic hurricane season. Laura's remnants later impacted the Netherlands, Germany, and Norway. The 12th named storm of the season, Laura formed out of a large extratropical area of low pressure located about 1,015 miles (1,633 km) west of the Azores on September 29. Laura slowly developed tropical characteristics throughout the day as it moved over warmer waters. On the afternoon of September 30, Laura had acquired enough tropical characteristics to be designated a tropical storm. Shortly after being declared tropical, Laura began to undergo an extratropical transition, which did not fully take place until the morning of October 1. Laura degenerated into a post-tropical cyclone later that morning, and the final advisory by the National Hurricane Center was issued. The remnants of Laura contributed to heavy rainfall and power outages in the British Isles, the Netherlands, and Norway on October 5 to 8.
Hurricane Grace was a short-lived Category 2 hurricane that contributed to the formation of the powerful 1991 Perfect Storm. Forming on October 26, Grace initially had subtropical origins, meaning it was partially tropical and partially extratropical in nature. It became a tropical cyclone on October 27, and ultimately peaked with winds of 105 mph (165 km/h). The storm had minor effects on the island of Bermuda as it passed to the south. A developing extratropical storm to the north turned Grace eastward; the hurricane was eventually absorbed into the large circulation of the larger low-pressure system. Fed by the contrast between cold air to the northwest and warm air from the remnants of Grace, this storm became a large and powerful nor'easter that caused extremely high waves and resulted in severe coastal damage along the East Coast of the United States.
The following is a glossary of tropical cyclone terms.
Hurricane Pablo was a late-season tropical cyclone that became the farthest east-forming hurricane in the North Atlantic tropical cyclone basin on record, beating the previous record set by Hurricane Vince in 2005. The seventeenth tropical/subtropical cyclone, sixteenth named storm and sixth hurricane of the 2019 Atlantic hurricane season, Pablo originated from a baroclinic cyclone a few hundred miles west of the Azores Islands. The precursor cyclone formed on October 22, traveling eastward towards the island chain. The system initially had multiple centers of circulation, but they consolidated into one small low-pressure system embedded within the larger extratropical storm. On October 25, the embedded cyclone developed into a subtropical cyclone, receiving the name Pablo. The cyclone continued eastwards, transitioning into a fully tropical storm later that day. Pablo quickly intensified between October 26 and 27, forming an eye and spiral rainbands. At 12:00 Coordinated Universal Time (UTC) on October 27, Pablo intensified into a Category 1 hurricane. The storm continued to strengthen, reaching its peak intensity of 80 mph (130 km/h) and a minimum central pressure of 977 mbar (28.9 inHg) at 18:00 UTC on the same day. The storm quickly weakened the next day, becoming extratropical again, and dissipated on October 29.
