Hurricane Nadine

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Hurricane Nadine
Category 1 hurricane (SSHWS/NWS)
Nadine Sep 30 2012 1535Z.jpg
Hurricane Nadine at peak intensity on September 30
FormedSeptember 10, 2012
DissipatedOctober 4, 2012
( Extratropical after October 3 [1] )
Duration3 weeks and 1 day
Highest winds 1-minute sustained:90 mph (150 km/h)
Lowest pressure978 mbar (hPa); 28.88 inHg
FatalitiesNone
DamageMinimal
Areas affected Azores, United Kingdom
Part of the 2012 Atlantic hurricane season

Hurricane Nadine was the fourth longest-lived Atlantic hurricane on record. The fourteenth tropical cyclone and named storm of the 2012 Atlantic hurricane season, Nadine developed from a tropical wave west of Cape Verde on September 10. By the following day, it had strengthened into Tropical Storm Nadine. After initially tracking northwestward, Nadine turned northward, well away from any landmass. Early on September 15, Nadine reached hurricane status as it was curving eastward. Soon after, an increase in vertical wind shear weakened Nadine and by September 16 it was back to a tropical storm. On the following day, the storm began moving northeastward and threatened the Azores but late on September 19, Nadine veered east-southeastward before reaching the islands. Nonetheless, the storm produced tropical storm force winds on a few islands. On September 21, the storm curved south-southeastward while located south of the Azores. Later that day, Nadine transitioned into a non-tropical low pressure area.

Tropical cyclone Rotating storm system with a closed, low-level circulation

A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain. Depending on its location and strength, a tropical cyclone is referred to by different names, including hurricane, typhoon, tropical storm, cyclonic storm, tropical depression, and simply cyclone. A hurricane is a tropical cyclone that occurs in the Atlantic Ocean and northeastern Pacific Ocean, and a typhoon occurs in the northwestern Pacific Ocean; in the south Pacific or Indian Ocean, comparable storms are referred to simply as "tropical cyclones" or "severe cyclonic storms".

Tropical cyclones and subtropical cyclones are named by various warning centers to provide ease of communication between forecasters and the general public regarding forecasts, watches, and warnings. The names are intended to reduce confusion in the event of concurrent storms in the same basin. Generally once storms produce sustained wind speeds of more than 33 knots, names are assigned in order from predetermined lists depending on which basin they originate. However, standards vary from basin to basin: some tropical depressions are named in the Western Pacific, while tropical cyclones must have a significant amount of gale-force winds occurring around the centre before they are named in the Southern Hemisphere.

2012 Atlantic hurricane season hurricane season in the Atlantic Ocean

The 2012 Atlantic hurricane season was the final year in a consecutive string of three very active seasons, although many of the storms were weak. It is tied with 1887, 1995, 2010, and 2011 for having the third-most named storms on record. It was also the third-costliest season, behind 2005 and 2017. The season officially began on June 1 and ended on November 30, dates that conventionally delimit the period during each year in which most tropical cyclones form in the Atlantic Ocean. However, Alberto, the first system of the year, developed on May 19 – the earliest date of formation since Tropical Storm Ana in 2003. A second tropical cyclone, Beryl, developed later that month. This was the first occurrence of two pre-season named storms in the Atlantic basin since 1951. It moved ashore in North Florida on May 29 with winds of 65 mph (100 km/h), making it the strongest pre-season storm to make landfall in the Atlantic basin. This season marked the first time since 2009 where no tropical cyclones formed in July. Another record was set by Hurricane Nadine later in the season; the system became the fourth-longest-lived tropical cyclone ever recorded in the Atlantic, with a total duration of 22.25 days. The final storm to form, Tony, dissipated on October 25 – however, Hurricane Sandy, which formed before Tony, became extratropical on October 29.

Contents

Due to favorable conditions, the remnants of Nadine regenerated into a tropical cyclone on September 24. After re-developing, the storm executed a cyclonic loop and meandered slowly across the eastern Atlantic. Eventually, Nadine turned south-southwestward, at which time it became nearly stationary. By September 28, the storm curved northwestward and re-strengthened into a hurricane. The tenacious cyclone intensified further and peaked with winds of 90  mph (150  km/h) on September 30. By the following day, however, Nadine weakened back to a 65 mph (105 km/h) tropical storm, as conditions became increasingly unfavorable. Strong wind shear and decreasing sea surface temperatures significantly weakened the storm. Nadine transitioned into an extratropical cyclone on October 3, and merged with an approaching cold front northeast of the Azores soon after. The remnants of Nadine passed through the Azores on October 4 and again brought relatively strong winds to the islands.

Miles per hour unit of speed

Miles per hour is an imperial and United States customary unit of speed expressing the number of statute miles covered in one hour. It is used in the United States, United Kingdom and some Commonwealth nations, notably in the Caribbean region.

Kilometres per hour unit of speed

The kilometre per hour is a unit of speed, expressing the number of kilometres travelled in one hour.

Extratropical cyclone type of cyclone

Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are low-pressure areas which, along with the anticyclones of high-pressure areas, drive the weather over much of the Earth. Extratropical cyclones are capable of producing anything from cloudiness and mild showers to heavy gales, thunderstorms, blizzards, and tornadoes. These types of cyclones are defined as large scale (synoptic) low pressure weather systems that occur in the middle latitudes of the Earth. In contrast with tropical cyclones, extratropical cyclones produce rapid changes in temperature and dew point along broad lines, called weather fronts, about the center of the cyclone.

Origins

Map plotting the track and the intensity of the storm, according to the Saffir-Simpson scale Nadine 2012 track.png
Map plotting the track and the intensity of the storm, according to the Saffir–Simpson scale

A large tropical wave emerged into the Atlantic Ocean from the west coast of Africa, on September 7. [1] The system passed south of Cape Verde on September 8, bringing disorganized showers and thunderstorms. [2] Around that time, the National Hurricane Center gave the system a medium chance of tropical cyclogenesis within 48 hours. A low pressure area developed along the axis of the tropical wave on September 9, which further increased convective activity. [1] The system was assessed with a high chance for tropical cyclone formation on September 10. [3] Based on satellite intensity estimates, the National Hurricane Center declared the disturbance as Tropical Depression Fourteen at 1200 UTC on September 10, while the storm was about 885 miles (1,425 km) west of Cape Verde. [1] [4]

National Hurricane Center Division of the United States National Weather Service

The National Hurricane Center (NHC) is the division of the United States' National Weather Service responsible for tracking and predicting tropical weather systems between the Prime Meridian and the 140th meridian west poleward to the 30th parallel north in the northeast Pacific Ocean and the 31st parallel north in the northern Atlantic Ocean. The agency, which is co-located with the Miami branch of the National Weather Service, is situated on the campus of Florida International University in University Park, Florida.

Tropical cyclogenesis

Tropical cyclogenesis is the development and strengthening of a tropical cyclone in the atmosphere. The mechanisms through which tropical cyclogenesis occurs are distinctly different from those through which temperate cyclogenesis occurs. Tropical cyclogenesis involves the development of a warm-core cyclone, due to significant convection in a favorable atmospheric environment.

Although thunderstorm activity was initially minimal around the center of circulation, a convective band associated with the depression was becoming more organized. [4] Late on September 10, convection began to increase slightly near the center, but because Dvorak intensity T-numbers were between 2.0 and 2.5, the depression was not upgraded to a tropical storm. [5] However, dry air briefly caused showers and thunderstorms to decrease later that day. Initially, it headed just north of due west around the southern periphery of a large subtropical ridge. However, by September 11, the depression re-curved northwestward. Later that day, the depression began to regain deep convection. Geostationary satellite imagery and scatterometer data indicated that the depression strengthened into Tropical Storm Nadine at 0000 UTC on September 12. [1]

Atmospheric circulation The large-scale movement of air, a process which distributes thermal energy about the Earths surface

Atmospheric circulation is the large-scale movement of air, and together with ocean circulation is the means by which thermal energy is redistributed on the surface of the Earth.

Dvorak technique

The Dvorak technique is a widely used system to estimate tropical cyclone intensity based solely on visible and infrared satellite images. Within the Dvorak satellite strength estimate for tropical cyclones, there are several visual patterns that a cyclone may take on which define the upper and lower bounds on its intensity. The primary patterns used are curved band pattern (T1.0-T4.5), shear pattern (T1.5–T3.5), central dense overcast (CDO) pattern (T2.5–T5.0), central cold cover (CCC) pattern, banding eye pattern (T4.0–T4.5), and eye pattern (T4.5–T8.0).

Ridge (meteorology) elongated region of high atmospheric pressure

A ridge or barometric ridge is a term in meteorology describing an elongated area of relatively high atmospheric pressure compared to the surrounding environment, without being a closed circulation. It is associated with an area of maximum anticyclonic curvature of wind flow. The ridge originates in the center of an anticyclone and stretch between two low-pressure areas, and the locus of the maximum curvature is called the ridge line. This phenomena is the opposite of a trough.

Strengthening and initial peak intensity

Hurricane Nadine at its initial peak intensity on September 15 Nadine Sept 15 2012 1610Z.jpg
Hurricane Nadine at its initial peak intensity on September 15

By September 12, a central dense overcast developed and due to favorable conditions, the National Hurricane Center noted the possibility of rapid deepening. [6] Intensification continued at a quicker albeit less than rapid rate on September 12. Later that day, sustained winds reached 65 mph (105 km/h). [7] [8] By early on September 13, convective banding wrapped almost completely around the center and cloud tops reached temperatures as low as −112  °F (−80  °C ). However, because microwave satellite data could not determine if an eye had developed, Nadine's intensity was held at 70 mph (110 km/h) – just below the threshold of hurricane status. [9] The National Hurricane Center noted that "the window for Nadine to strengthen may be closing", citing computer model consensus of an increase in wind shear and little change in structure. [10] The storm then began experiencing moderate southwesterly wind shear on September 13, generated by a mid- to upper-level trough and a shear axis located a few hundred miles to the west of Nadine. As a result, the storm struggled to develop an eye and the center became more difficult to locate. [11]

Central dense overcast

The central dense overcast, or CDO, of a tropical cyclone or strong subtropical cyclone is the large central area of thunderstorms surrounding its circulation center, caused by the formation of its eyewall. It can be round, angular, oval, or irregular in shape. This feature shows up in tropical cyclones of tropical storm or hurricane strength. How far the center is embedded within the CDO, and the temperature difference between the cloud tops within the CDO and the cyclone's eye, can help determine a tropical cyclone's intensity. Locating the center within the CDO can be a problem for strong tropical storms and with systems of minimal hurricane strength as its location can be obscured by the CDO's high cloud canopy. This center location problem can be resolved through the use of microwave satellite imagery.

Fahrenheit unit of temperature

The Fahrenheit scale is a temperature scale based on one proposed in 1724 by Dutch–German–Polish physicist Daniel Gabriel Fahrenheit (1686–1736). It uses the degree Fahrenheit as the unit. Several accounts of how he originally defined his scale exist. The lower defining point, 0 °F, was established as the freezing temperature of a solution of brine made from equal parts of ice, water and a salt. Further limits were established as the melting point of ice (32 °F) and his best estimate of the average human body temperature. The scale is now usually defined by two fixed points: the temperature at which water freezes into ice is defined as 32 °F, and the boiling point of water is defined to be 212 °F, a 180 °F separation, as defined at sea level and standard atmospheric pressure.

Celsius Scale and unit of measurement for temperature

The Celsius scale, also known as the centigrade scale, is a temperature scale used by the International System of Units (SI). As an SI derived unit, it is used worldwide. In the United States, the Bahamas, Belize, the Cayman Islands and Liberia however, Fahrenheit remains the preferred scale for everyday temperature measurement. The degree Celsius can refer to a specific temperature on the Celsius scale or a unit to indicate a difference between two temperatures or an uncertainty. It is named after the Swedish astronomer Anders Celsius (1701–1744), who developed a similar temperature scale. Before being renamed to honor Anders Celsius in 1948, the unit was called centigrade, from the Latin centum, which means 100, and gradus, which means steps.

Although the storm was disorganized, a scatterometer pass indicated tropical storm force winds extended outward up to 230 miles (370 km). The satellite appearance of Nadine became more ragged by September 14. Despite this, the storm remained just below hurricane status and the National Hurricane Center noted the possibility of intensification if wind shear decreased in the next few days. Nadine turned northward on September 14 as it tracked along the periphery of a subtropical ridge. [12] Soon after, a Tropical Rainfall Measuring Mission (TRMM) pass indicated that core convection began re-organizing. However, because wind shear displaced the mid-level circulation to the north of the low-level circulation, Nadine was not upgraded to a hurricane. [13] Because Nadine would approach colder sea surface temperatures, significant strengthening was considered unlikely. [13] Due to an increase in satellite intensity estimates and re-organization, Nadine was upgraded to a hurricane at 1800 UTC on September 14. Six hours later, Nadine reached an initial peak intensity with winds of 80 mph (130 km/h). [1] Satellite imagery indicated that a ragged eye feature was attempting to develop late on September 15. [14]

Tropical Rainfall Measuring Mission

The Tropical Rainfall Measuring Mission (TRMM) was a joint space mission between NASA and the Japan Aerospace Exploration Agency (JAXA) designed to monitor and study tropical rainfall. The term refers to both the mission itself and the satellite that the mission used to collect data. TRMM was part of NASA's Mission to Planet Earth, a long-term, coordinated research effort to study the Earth as a global system. The satellite was launched on November 27, 1997 from the Tanegashima Space Center in Tanegashima, Japan. TRMM operated for 17 years, including several mission extensions, before being decommissioned in April 2015. TRMM re-entered Earth's atmosphere on June 16, 2015.

Weakening and initial post-tropical transition

Tropical Storm Nadine passing south of the Azores on September 20 Nadine Sept 20 2012 1450Z.jpg
Tropical Storm Nadine passing south of the Azores on September 20

Late on September 15, National Hurricane Center forecaster Robbie Berg noted that Nadine began "to look a little more ragged", as microwave data observations noted shearing of deep convection to the northeast of the center. [15] Late on September 16, the eye became tilted and disappeared, convective bands began disorganizing, and the overall shower and thunderstorm activity waned since early that day. [16] Nadine weakened back to a tropical storm on September 17 and a trough reduced its satellite appearance. [1] [17]

Dry air began impacting Nadine on September 17, though outflow from the storm prevented significant weakening. [18] Despite a large flare of deep convection over the northern semicircle, Nadine weakened slightly later that day. [19] Further weakening occurred on the following day, after the burst in deep convection on September 17 deteriorated. [20] Later on September 18, most of the deep convection dissipated. The strongest showers and thunderstorms that remained were in a band to the west and northwest of Nadine's center. [21]

Nadine threatened the Azores while moving northeastward and then northward between September 18 and September 19, though a blocking ridge prevented the storm from approaching closer to the islands. Its closest approach to the Azores was about 150 miles (240 km) south-southwest of Flores Island on September 19. [1] The storm then re-curved east-southeastward on September 20, after the ridge weakened and the mid- to upper-level trough deepened. [1] By late on September 21, much of the remaining deep convection was composed of only a ragged convective band with warming cloud tops. [22] Operationally, the National Hurricane Center re-classified Nadine as a subtropical storm at 2100 UTC on September 21, due to an above-average, asymmetrical wind field and an upper-level low pressure area near the center. [23] However, post-season analysis concluded that Nadine degenerated into a non-tropical low pressure area three hours earlier. [1]

Regeneration, peak intensity, and demise

Tropical Storm Nadine on September 25 Nadine Sept 25 2012 1510Z.jpg
Tropical Storm Nadine on September 25

Early on September 22, the National Hurricane Center noted that regeneration into a tropical cyclone was a distinct possibility. [24] The remnant low pressure area soon moved over warmer seas and a low-shear environment, causing deep convection to re-develop. Thus, Nadine became a tropical storm at 0000 UTC on September 23. Another blocking ridge over the Azores forced Nadine to move west-northwestward on September 24, causing it to execute a small cyclonic loop. Although winds increased to 60 mph (95 km/h), the storm weakened again and decreased to a 45 mph (72 km/h) tropical storm on September 25. [1] Despite this regression, satellite imagery indicated that Nadine developed an eye-like feature. [25] However, the National Hurricane Center later noted that it was a cloud-free region near the center of the storm. [26] By September 26, Nadine curved south-southwestward to southwestward around the southeastern portion of a mid- to upper-level ridge located over the western Atlantic. [1]

After minimal change in strength for several days, Nadine finally began to intensify on September 27, due to sea surface temperatures warmer than 79 °F (26 °C). At 1200 UTC on September 28, Nadine re-strengthened into a Category 1 hurricane on the Saffir–Simpson hurricane wind scale. [1] Around that time, satellite imagery indicated that the storm re-developed an eye feature. [27] After becoming disorganized, the National Hurricane Center erroneously downgraded Nadine to a tropical storm on September 29 [28] before upgrading it to a hurricane again six hours later. [29] Nadine had actually remained a hurricane and was intensifying further. [1] Winds increased to 85 mph (140 km/h) on September 30, after the eye became more distinct. [30] At 1200 UTC, the storm attained its peak intensity with maximum sustained winds of 90 mph (150 km/h) and a minimum barometric pressure of 978 mbar (28.9 inHg). [1]

After peak intensity, Nadine began weakening once again and deteriorated to a tropical storm at 1200 UTC, on October 1. [1] Northwesterly winds began to increase on October 3, after an upper-level trough that was causing low wind shear moved eastward. [31] A few hours later, the low-level center became partially exposed, [32] before becoming fully separated from the convection by 1500 UTC. [32] Due to strong wind shear and cold sea surface temperatures, showers and thunderstorms rapidly diminished, and by late on October 3, Nadine became devoid of any deep convection. [33] At 0000 UTC on October 4, Nadine transitioned into an extratropical low-pressure area, while located about 195 miles (315 km) southwest of the central Azores. The low rapidly moved northeastward, degenerated into a trough of low pressure, and was absorbed by a cold front later that day. [1]

Impact and records

Tropical Storm Nadine re-approaching the Azores on October 3 Tropical Storm Nadine 2012-10-03 1245 UTC.jpg
Tropical Storm Nadine re-approaching the Azores on October 3

Tropical cyclone warnings and watches were issued on two separate occasions as Nadine approached the Azores. At 1000 UTC on September 18, a tropical storm watch was issued for the islands of Flores and Corvo. Although the tropical storm watch was discontinued at 2100 UTC, a tropical storm warning was implemented at that time for the islands of Corvo, Faial, Flores, Graciosa, Pico, São Jorge, and Terceira. At 1500 UTC on September 19, a tropical storm warning was also issued for São Miguel and Santa Maria. All watches and warnings were discontinued by late on September 21. After re-generating, Nadine posed a threat to the Azores again, which resulted in a tropical storm watch for the entire archipelago at 1500 UTC on October 1. Nine hours later, 0000 UTC on the following day, the watch was upgraded to a tropical storm warning. After Nadine became extratropical, the warning was discontinued. [1] On the storm's second approach toward the Azores, schools were closed and flight were cancelled. [34]

Late on September 20, Flores reported a wind gust of 46 mph (74 km/h). [35] A sustained wind speed of 62 mph (100 km/h) and a gust up to 81 mph (130 km/h) were reported at Horta on the island of Faial, as Nadine passed to the south on September 21. During the second Azores impact on October 4, the highest sustained wind speed reported was 38 mph (61 km/h) on São Miguel, while the strongest gust was 87 mph (140 km/h) at the Wind Power Plant on Santa Maria. [1] On Pico Island, the pavement of the sports hall of the primary and secondary school in Lajes do Pico was destroyed. [36] The remnants of Nadine produced a plume of moisture that dropped heavy rainfall over the United Kingdom, particularly in England and Wales, reaching 5.12 in (130 mm) at Ravensworth in the former. The rains flooded houses and disrupted roads and rails. [37] [38]

Nadine lasted a total of 24 days as a tropical, subtropical, and post-tropical cyclone, including 22.25 days as a tropical system. This makes it the fourth longest-lasting Atlantic tropical cyclone on record, only behind the 1899 San Ciriaco hurricane at 28 days, Hurricane Ginger in 1971 at 27.25 days, and Hurricane Inga in 1969 at 24.75 days. When only counting time spent as a tropical storm or hurricane – 20.75 days – Nadine is the third longest-lasting, behind only Hurricane Ginger in 1971 and the 1899 San Ciriaco hurricane. [1] When Nadine was upgraded to a hurricane at 1800 UTC on September 14, it marked the third-earliest forming eighth hurricane, behind only an unnamed system in 1893 and Ophelia in 2005. [39]

See also

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The 2018 Atlantic hurricane season was the third in a consecutive series of above-average and damaging Atlantic hurricane seasons, featuring 15 named storms, 8 hurricanes, and 2 major hurricanes, which caused a total of over $50.205 billion in damages. The season officially began on June 1, 2018, and ended on November 30, 2018. These dates historically describe the period each year when most tropical cyclones form in the Atlantic basin and are adopted by convention. The formation of Tropical Storm Alberto on May 25, marked the fourth consecutive year in which a storm developed before the official start of the season. The next storm, Beryl, became the first hurricane to form in the eastern Atlantic during the month of July since Bertha in 2008. Chris, upgraded to a hurricane on July 10, became the earliest second hurricane in a season since 2005. No hurricanes formed in the North Atlantic during the month of August, marking the first season since 2013, and the eighth season on record, to do so. On September 5, Florence became the first major hurricane of the season. On September 12, Joyce formed, making 2018 the first season since 2008 to feature four named storms active simultaneously. On October 9, Michael became the second major hurricane of the season, and a day later, it became the first Category 5 hurricane to make landfall in the continental United States since Hurricane Andrew in 1992. With Michael, 2018 became the third consecutive season to feature at least one Category 5 hurricane. With the formation of Oscar on October 26, the season is the first on record to see seven storms that were subtropical at some point in their lifetimes.

Hurricane Carlos (2015)

Hurricane Carlos was an unusually small tropical cyclone which affected the western coast of Mexico in June 2015. Forming as the third named storm and hurricane of the annual hurricane season, Carlos developed from a trough first noted by the National Hurricane Center on June 7. The disturbance gradually organized and was designated as a tropical depression three days later while south of the Mexican Pacific coast. Drifting slowly northwestward, the depression was upgraded further to a tropical storm. Although persistent wind shear and dry air hampered intensification early on, Carlos strengthened into a hurricane on June 13 after moving into a more favorable environment. However, the return of dry air and upwelling of cooler waters caused the system to deteriorate into a tropical storm. Paralleling the Mexican coast, Carlos later regained hurricane intensity on June 15 and attained peak winds of 90 mph (150 km/h) a day later. The reprieve was brief, however, as the onset of wind shear, land interaction, and dry air afterward led to rapid weakening. On June 17, Carlos degenerated into a remnant area of low pressure, having made landfall in Jalisco earlier that day. By the morning of June 18, Carlos was declared to have completely dissipated.

Hurricane Danny (2015)

Hurricane Danny in August 2015 was the first major hurricane to develop between the Lesser Antilles and Western Africa since Hurricane Julia in 2010. The hurricane originated from a well-defined tropical wave that emerged over the Atlantic Ocean on August 14. Traveling west, the system gradually coalesced into a tropical depression by August 18. After becoming a tropical storm later that day, dry air slowed further development. On August 20–21, dry air became removed from the system, and Danny rapidly intensified into a Category 3 on the Saffir–Simpson hurricane wind scale. Its peak was short-lived as wind shear soon increased and prompted significant weakening. Degrading to a tropical storm by August 23, Danny approached the Lesser Antilles. It degenerated into a tropical wave as it traversed the archipelago on August 24 and was last noted over Hispaniola the following day.

Meteorological history of Hurricane Dennis

The meteorological history of Hurricane Dennis spanned twenty-two days, beginning with its inception as a tropical wave over Africa on June 26, 2005, and terminating with its dissipation on July 18 over the Great Lakes of North America. The incipient wave that became Dennis emerged over the Atlantic Ocean on June 29 and moved briskly to the west. Dry air initially inhibited development, though once this abated the wave was able to consolidate into a tropical depression on July 4. The depression soon crossed Grenada before entering the Caribbean Sea whereupon increasingly favorable environmental factors, such as low wind shear and high sea surface temperatures, fueled intensification. Turning west-northwest, the system achieved tropical storm status on July 5 and hurricane status the following day.

Hurricane Alex (2016) Atlantic hurricane

Hurricane Alex was the first Atlantic hurricane in January since Hurricane Alice in 1955. Hurricane Alex originated as an extratropical cyclone near the Bahamas on January 7, 2016. The system initially traveled northeast, bypassing Bermuda on January 8 before turning southeast. It subsequently deepened and acquired hurricane-force winds by January 10. After weakening slightly, the system eventually turned east and northeast as it acquired tropical characteristics. On January 12, it developed into a subtropical cyclone well south of the Azores, becoming the first tropical or subtropical system during January in the North Atlantic since Tropical Storm Zeta in 2006. As it turned north-northeast, Alex transitioned into a tropical cyclone on January 14 and became a hurricane. The storm peaked as a Category 1 on the Saffir–Simpson scale with maximum sustained winds of 85 mph (140 km/h) and a central pressure of 981 mbar. After weakening slightly, Alex made landfall on Terceira Island as a tropical storm on January 15. Concurrently, Alex began transitioning back into an extratropical cyclone; it completed this cycle hours after moving away from the Azores. The system ultimately merged with another extratropical cyclone over the Labrador Sea on January 17.

Meteorological history of Hurricane Matthew

Hurricane Matthew was the first Category 5 Atlantic hurricane since Felix in 2007 and the southernmost Category 5 Atlantic hurricane on record. The system originated from a tropical wave that emerged off the west coast of Africa on September 22, and ultimately dissipated as an extratropical cyclone near Atlantic Canada on October 10. Late on September 29, it began a period of explosive intensification that brought it to Category 5 strength early on October 1. It weakened slightly and remained a Category 4 until its landfalls in Haiti and Cuba, afterwards it traversed through the Bahamas and paralleled the coast of Florida until making landfall in South Carolina as a Category 1 hurricane. Matthew later transitioned into a post-tropical cyclone on October 10.

Meteorological history of Hurricane Harvey

Hurricane Harvey was the costliest tropical cyclone on record, inflicting roughly $125 billion in damage across the Houston metropolitan area and Southeast Texas. It lasted from mid-August until early September 2017, with many records for rainfall and landfall intensity set during that time. The eighth named storm, third hurricane, and first major hurricane of the 2017 Atlantic hurricane season, Harvey originated from a broad area of low pressure southwest of Cape Verde that was first monitored on August 13. Tracking steadily westward, the disturbance developed strong convection, a well-defined circulation, and sustained tropical storm-force winds, leading to the classification of Tropical Storm Harvey late on August 17. Moderate easterly vertical wind shear kept Harvey weak, as it continued westwards into the Caribbean Sea; despite repeated predictions for gradual intensification by the National Hurricane Center, Harvey eventually opened up into a tropical wave on August 19. The remnants of Harvey continued to move westwards and reached the Yucatán Peninsula on August 22, and was forecast to regenerate into a tropical cyclone after exiting land.

2018 Pacific hurricane season Period of formation of tropical cyclones in the Eastern Pacific Ocean in 2018

The 2018 Pacific hurricane season produced the highest accumulated cyclone energy (ACE) value on record. With 23 named storms, it was the fourth-most active season on record, tied with 1982. The season officially began on May 15 in the eastern Pacific, and on June 1 in the central Pacific; they both ended on November 30. These dates conventionally delimit the period of each year when most tropical cyclones form in the Pacific basin, as illustrated when the first tropical depression formed on May 10.

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