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The 2017 Pacific hurricane season was an above average Pacific hurricane season in terms of named storms,[nb 1] though less active than the previous three, featuring eighteen named storms, nine hurricanes, and four major hurricanes.[nb 2] Despite the considerable amount of activity, most of the storms were weak and short-lived. The season officially started on May15 in the eastern Pacific Ocean, and on June1 in the central Pacific; they both ended on November30. These dates conventionally delimit the period of each year when most tropical cyclones form in the respective regions. However, the formation of tropical cyclones is possible at any time of the year, as illustrated in 2017 by the formation of the season's first named storm, Tropical Storm Adrian, on May9. At the time, this was the earliest formation of a tropical storm on record in the eastern Pacific basin proper (east of 140°W). The season saw near-average activity in terms of accumulated cyclone energy (ACE), in stark contrast to the extremely active seasons in 2014, 2015, and 2016; and for the first time since 2012, no tropical cyclones formed in the Central Pacific basin. However, for the third year in a row, the season featured above-average activity in July, with the ACE value being the fifth highest for the month. Damage across the basin reached $375.28million (2017USD),[nb 3] while 45people were killed by the various storms.
Prior to the start of this season, the National Hurricane Center (NHC) changed its policy to permit issuance of advisories on disturbances that were not yet tropical cyclones but had a high chance to become one, and were expected to bring tropical storm or hurricane conditions to landmasses within 48hours. As a result of this change, watches and warnings could be issued by local authorities. Such systems would be termed as "Potential Tropical Cyclones".[2] The first system to receive this designation was Potential Tropical Cyclone Fourteen-E, which developed into Tropical Storm Lidia south-southeast of the Baja California Peninsula on August30.
Forecasts include weekly and monthly changes in important factors that help determine the number of tropical storms, hurricanes, and major hurricanes within a particular year. According to the National Oceanic and Atmospheric Administration (NOAA), the average hurricane season in the Eastern and Central Pacific between 1981 and 2010 contained approximately 15 tropical storms, 7 hurricanes, and 3 major hurricanes. The NOAA generally classifies a season as above average, average, or below average based on the cumulative ACE index, but occasionally the number of tropical storms, hurricanes, and major hurricanes within a hurricane season is also considered.
On May25, 2017, the National Oceanic and Atmospheric Administration released its annual forecast, predicting an 80% chance of a near- to above-average season in both the Eastern and Central Pacific basins, with a total of 14–20 named storms, 6–11 hurricanes, and 3–7 major hurricanes.[nb 4][4] During May 28, the Servicio Meteorológico Nacional (SMN) issued its first forecast for the season, predicting a total of 16 named storms, 10 hurricanes, and 6 major hurricanes to develop.[5]
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Tropical Storms Greg (left), Irwin (center), and Hurricane Hilary (right) spanning the East Pacific on July24
Although hurricane season in the eastern Pacific does not officially begin until May15, and on June1 in the central Pacific,[6] activity began several days prior with the formation of a tropical depression in the eastern region on May9. This was the earliest formation of a tropical cyclone on record in the eastern Pacific basin proper,[7] until broken by Tropical Depression One-E in 2020. When it intensified into Tropical Storm Adrian a few hours later, the system became the earliest named storm on record in the region,[8] a record that stood until broken by Tropical Storm Andres in 2021.[9] Near normal activity occurred in June, with Tropical Storm Calvin formed on June 11, and Hurricane Dora on June 25.[10] For the third year in a row, July featured above average activity, with the fifth highest ACE value for that month on record.[11]This total was due to long-lived hurricanes Eugene, Fernanda, Hilary, and Irwin. August saw significantly less activity, with only three storms forming in the month; however it featured Hurricane Kenneth, the third major hurricane of the season. September featured four storms, including Hurricane Otis, which became the fourth major hurricane of the season. Only two storms formed after October 1, Ramon and Selma. Both did not attain hurricane status, though Selma became the first and last storm to make landfall in El Salvador. No systems were active in November for the first time since the 2010 season.[citation needed][original research?] The Accumulated Cyclone Energy index for the 2017 Pacific hurricane season as calculated by Colorado State University using data from the National Hurricane Center was approximately 100.7units,[nb 5][12] about 20 percent near average.
On May5, the National Hurricane Center (NHC) indicated that an area of low pressure was forecast to form south of Mexico over subsequent days, with the possibility of tropical cyclone development thereafter.[13] A broad cyclonic circulation began to develop as expected late on May7,[14] gradually organizing into the season's first tropical depression by 21:00UTC on May9, while located about 545mi (875km) south-southeast of Salina Cruz, Mexico.[15] The depression intensified into Tropical Storm Adrian six hours later.[9] Initially, forecasts expected the small storm to intensify into a powerful hurricane. Shortly after reaching peak intensity early on May10, an unexpected increase in mid-level wind shear caused Adrian to quickly weaken and degenerate to a remnant low by 00:00UTC on May11.[16] Adrian's remnant low persisted for another day, before dissipating on May12.[16]
A tropical wave emerged off the western coast of Africa on May18 and entered the East Pacific about a week later, where steady organization led to the formation of a tropical depression around 12:00UTC on May31. Embedded within southwesterly flow around a large upper-level trough across northern Mexico, the depression moved steadily northeast in a favorable environment, and it intensified into Tropical Storm Beatriz by 06:00UTC on June1. After attaining peak winds of 45mph (70km/h), the system made landfall around 00:00UTC on June2 about 25miles (40km) west of Puerto Ángel before the mountainous terrain of Mexico quickly made Beatriz dissipate inland twelve hours later.[17]
In the state of Oaxaca, flights out of Bahías de Huatulco International Airport were cancelled and schools were closed until June3. Dozens of roads were impassable due to mudslides and flooding; numerous locales received over 4in (102mm) of rain, with rainfall at a maximum of 19.07in (484.4mm) in Huatulco.[17] Numerous landslides caused significant disruption across the state; the storm blocked large areas of Federal Highway 200 in Oaxaca. A landslide in San Marcial Ozolotepec killed two girls and buried several houses, while another in San Carlos Yautepec killed a woman.[18] As of June 4, a total of six people have been killed—five in Oaxaca and two in Tehuantepec.[19] Damage in Oaxaca reached MXN$3.2 billion (US$172 million).[20]
In the second week of June, the NHC forecast the development of a broad area of low pressure a few hundred miles south of Mexico over the next several days.[21] This prediction came to fruition on June9,[22] and the fledgling disturbance steadily organized into a tropical depression by 12:00UTC on June11 while located about 150mi (240km) south-southeast of Salina Cruz.[23] It was slow to organize initially due to moderate easterly wind shear as it drifted northwestwards;[24] by 18:00UTC on June12, however, the tropical depression intensified into Tropical Storm Calvin.[23] Intensifying slightly to reach winds of 45mph (70km/h),[23] Calvin made landfall halfway between Salina Cruz and Puerto Ángel, near Paja Blanca, around 00:00UTC on June13.[25] Just 12hours later, Calvin dissipated into a remnant low.[23] The remnants of the storm caused heavy rainfall and some flooding in the area,[26] however no fatalities were reported.[23] Calvin affected proximate areas of Mexico as Tropical Storm Beatriz less than two weeks earlier, causing at least 70million pesos (US$3.88million) additional damage in Oaxaca.[27]
A large gyre developed over Central America around June15. A trough detached from the gyre and drifted across just south of the Gulf of Tehuantepec between June21 and June23. By June23, a tropical wave associated with the remnants of Tropical Storm Bret in the Atlantic began merging with the trough. A surface low formed early on the next day, followed by the development of a tropical depression at 18:00UTC. Initially located about 230mi (370km) south-southeast of Acapulco, the depression moved west-northwestward due to a mid-tropospheric ridge, which stretched from northern Mexico westward into nearby Pacific waters. At 06:00UTC on June25, the depression intensified into Tropical Storm Dora. Thereafter, favorable conditions including low wind shear and warm sea surface temperatures allowed Dora to undergo rapid intensification, becoming a hurricane at 06:00UTC on June26 and a Category2 hurricane about six hours later.[28]
With impressive outflow and an eye apparent on satellite imagery,[29] the storm peaked with maximum sustained winds of 105mph (170km/h) and a minimum barometric pressure of 974mbar (28.8inHg) by 18:00UTC June26. Dora remained a Category2 hurricane for about 12more hours before beginning to rapidly weaken over cooler sea surface temperatures and in an environment of drier air, falling to Category1 intensity at 06:00UTC on June27 and deteriorating to a tropical storm around 18:00UTC. The storm later degenerated into a remnant low near Socorro Island early on June28, after all of the storm's convection had been diminished. The remnant low moved slowly over the eastern Pacific before dissipating early on July1.[28] The outer bands of Dora brought heavy rains to Guerrero, resulting in flash floods that inundated 20homes. Overall damage was minor, however.[30]
Hurricane Eugene developed from a disturbance located 765mi (1,230km) south of the southern tip of the Baja California Peninsula on July 7.[31] On the following day, Eugene underwent a period of rapid intensification; in an 18-hour period starting at 21:00UTC on July8, Eugene intensified from a tropical storm with 70mph (115km/h) winds to a Category3 hurricane with 115mph (185km/h) winds, making it the first major hurricane of the season.[32][33] However, by 12 hours later, the entrainment of dry air caused Eugene to weaken to a Category2 hurricane,[34] and due to traveling over cooler waters, Eugene weakened to a tropical storm on the following day.[35] As the coverage of deep convection steadily dwindled, Eugene fell to tropical depression intensity around 15:00UTC on July12, and degenerated to a remnant low six hours later.[36][37]
Dangerous rip currents combined with swells of 4 to 8ft (1.2 to 2.4m) across southern California resulted in hundreds of rescues. On July10 alone, lifeguards in Huntington Beach made 200rescues while 600 were made in Los Angeles County; lifeguards also responded to 700medical emergencies.[38]
Late on July10, the NHC began monitoring a broad area of low pressure several hundred miles southwest of Manzanillo. Contrary to predictions of gradual development,[39] the disturbance rapidly organized into a tropical depression by 03:00UTC on July12,[40] and further strengthened to become Tropical Storm Fernanda around 15:00UTC that day.[41] The nascent cyclone initially battled moderate northeasterly wind shear, with its low-level circulation displaced to the northeastern edge of the deep convection.[42] This period of unfavorable upper-level winds was brief, and soon afterwards Fernanda commenced a period of rapid intensification, intensifying into a hurricane at 21:00UTC on July13.[43] A well-defined eye formed within a growing central dense overcast, and Fernanda further intensified into a major hurricane early on July 14.[44] Only six hours later, the system was upgraded to a Category 4 hurricane.[45] At 10.9°N, Fernanda became the second strongest hurricane to occur at such a low latitude in the Eastern Pacific, only behind Hurricane Olaf (2015).[46]
With expansive upper-level outflow and spiral bands, a distinct eye, and a symmetric central dense overcast, Fernanda attained peak winds of 145mph (235km/h) around 03:00UTC on July15.[47] A series of microwave passes around that time began to indicate the formation of a secondary eyewall that halted the cyclone's development as it tracked west-northwest to northwest.[48] The eyewall replacement cycle concluded early on July16, allowing Fernanda to remain a powerful hurricane amid favorable environmental conditions.[49] By late on July18, however, cooler ocean temperatures and a more stable environment prompted the storm's weakening trend.[50] Fernanda fell below hurricane intensity shortly before entering the Central Pacific as it succumbed to stronger southwesterly wind shear,[51] becoming a tropical depression at 03:00 UTC on July 21,[52] and after failing to produce sustained deep convection, degenerated to a remnant low about 500miles (805km) east of Hilo, Hawaii, by 21:00UTC on July22.[53]
A low-pressure trough began producing disorganized convection over the waters of the Pacific Ocean, well to the south of Baja California Peninsula, on July14.[54] Despite only marginally conducive environmental conditions, the disturbance began to show signs of organization two days later,[55] and it attained tropical depression status by 06:00UTC on July17.[56] Strong west-northwesterly wind shear confined the storm's intermittent bursts of convection well to the southwest of its low-level circulation, and the depression consequently failed to produce winds above 35mph (55km/h).[57] The system's center later degenerated into a low-pressure trough within the Intertropical Convergence Zone, prompting the NHC to discontinue advisories at 21:00UTC on July20.[58]
On July12, the NHC forecast the formation of a broad area of low pressure south of Mexico over subsequent days.[59] The disturbance formed two days later and slowly organized into a tropical depression by 15:00UTC on July17.[60][61] The tropical cyclone battled strong west-northwesterly wind shear after formation, intensifying into Tropical Storm Greg by 09:00UTC on July18, as deep convection burst near the center. However, the storm remained in a steady state for several days thereafter, despite continued predictions of intensification.[62][63] Ultimately, given global models' poor handling of the environment, NHC lowered their intensity forecast for Greg.[64] The cyclone continued west for the remainder of its life and maintained a similar convective structure, with intermittent bursts of deep convection near the center.[65] Approaching the Central Pacific, Greg's low-level circulation became increasingly difficult to locate as it moved into a cooler, drier environment intertwined by increasing southerly wind shear, and the system weakened to a tropical depression around 21:00UTC on July25.[66] It degenerated to a remnant low 24 hours later.[67]
Part of an exceptionally active July, the NHC began highlighting the far eastern reaches of the Pacific basin on July19 for tropical development in later days.[68] A large area of disturbed weather progressed westward across Costa Rica later that day,[69] steadily organizing into a tropical depression by 15:00UTC on July21.[70] The cyclone failed to organize immediately after formation, and its low-level center migrated to the southern extent of associated convection.[71] By 03:00UTC on July23, though, better defined banding features and a more organized convective structure led the NHC to designate the system as Tropical Storm Hilary.[72] Over the coming hours, the cyclone's convective structure evolved into a small central dense overcast while hints of an eye became apparent;[73] in accordance with satellite estimates, Hilary was upgraded to a hurricane at 09:00UTC on July24.[74] A moist environment and warm ocean waters propelled Hilary to its peak as a Category2 hurricane with winds of 110mph (175km/h) 24 hours later, at which time its core was most symmetric.[75] After maintaining its intensity, the hurricane began to weaken late on July26 as northerly wind shear increased.[76] It fell back to tropical storm intensity around 03:00UTC on July27, and ultimately degenerated to a remnant low four days later.[77][78]
On July16, the NHC highlighted the expected formation of an area of low pressure south of Mexico later that week.[79] A tropical wave began producing disorganized cloudiness three days later,[68] and the broad system slowly organized into a tropical depression by 15:00UTC on July22.[80] Its structure changed little after formation, impacted by strong wind shear; despite this, satellite wind data indicated the cyclone intensified into Tropical Storm Irwin by 09:00UTC on July23.[81] Over the next 24 hours, deep convection began to wrap around the center and a mid-level eye formed as environmental conditions improved;[82] by 09:00UTC on July25, Irwin intensified into a hurricane.[83] Although coolest cloudtops were located in the western semicircle of the system, a well-defined eye and convection in the eyewall propelled Irwin to its peak with winds of 90mph (145km/h) late on July25.[84] Almost immediately, outflow from nearby Hurricane Hilary increased wind shear over the system and caused it to begin weakening;[85] Irwin rapidly fell to tropical storm strength around 15:00UTC on July26.[86] Contrary to projections of continued weakening, however, the storm's cloud pattern maintained or even improved over subsequent days as it passed over marginal ocean temperatures.[87] Finally, after losing its deep convection and being reduced to a swirl of low-level clouds, Irwin was declared a remnant low around 21:00UTC on August1.[88]
On July28, the NHC noted the possibility of an area of low pressure well south of Mexico developing over subsequent days.[89] An area of disorganized showers and thunderstorms associated with a tropical wave materialized three days later, but little change occurred thereafter.[90] Early on August3, a surface circulation formed in association with concentrating convection,[91] and this process led to the formation of a tropical depression by 06:00UTC the next day.[92] The newly formed cyclone did not intensify after designation, and its low- and mid-level circulations separated by over 265mi (425km) on August5 due strong easterly wind shear.[93] Falling short of the tropical storm criteria, the short-lived depression was declared a remnant low at 18:00UTC that day.[92] The lingering vortex slowed its northwestward motion and executed a counter-clockwise loop, before dissipating completely 205miles (335km) southwest of the Baja California Peninsula on August8.[92]
The NHC began monitoring a strong tropical wave over the eastern Caribbean on August3.[94] The feature pushed westward, developing into Hurricane Franklin before making landfall on the Yucatán,[95] and attaining its peak as a Category1 hurricane before making landfall near Vega de Alatorre, Veracruz on August10.[96] Although its low-level circulation dissipated, the NHC in days prior noted the potential for Franklin's mid-level remnants to reform in the East Pacific.[97] The remnants of Franklin induced a surface low off the coast of southwestern Mexico on August11, and steady organization led to the formation of Tropical Storm Jova by 03:00UTC the next day.[98] On a westward course, Jova was plagued by strong wind shear from an area of high pressure over northwestern Mexico, with a very disorganized appearance on satellite.[99] After lacking sufficient organization to be declared a tropical cyclone, the storm was declared a remnant low around 03:00UTC on August14.[100]
On August12, the NHC noted the potential for an area of low pressure to form well south of Baja California Peninsula during the following days.[101] A large area of disturbed weather developed two days later as predicted;[102] however, organization was slow to occur, and a tropical depression only formed four days later, around 15:00UTC on August18.[103] The newly formed cyclone embarked on a west to west-northwest course, intensifying into Tropical Storm Kenneth early on August19 and further into a hurricane by 15:00UTC on August20.[104] Despite forecasts of only slight additional intensification,[105] Kenneth's small size allowed it to begin to rapidly intensified, with its eye warming dramatically and the surrounding cloud tops cooling quickly. The cyclone attained major hurricane strength around 03:00UTC on August21,[106] and six hours later reached its peak as a Category4 hurricane with sustained winds of 130mph (210km/h).[107] Progressively cooler sea surface temperatures and increasing wind shear caused Kenneth to steadily weaken following the intensification trend, with its inner core eroding and low-level circulation becoming displaced.[108] By 21:00UTC on August22, the storm weakened below hurricane strength.[109] On the following day, at 21:00 UTC, Kenneth was declared to be post-tropical. The remnant low meandered due to weak steering currents, before finally dissipating on August 27.
A vigorous tropical wave emerged off the western coast of Africa on August16; it crossed Central America into the East Pacific on August25. Part of a large cyclonic gyre, the disturbance failed to organize for several days—despite already producing tropical storm-force winds—amid high wind shear from Hurricane Harvey in the Gulf of Mexico. After Harvey weakened, however, an increase in the system's organization led to the formation of Tropical Storm Lidia around 18:00UTC on August30. Flow between a subtropical high and upper-level trough directed Lidia on a north-northwest track, and the cyclone strengthened to a peak of 65mph (105km/h) later on August31. Lidia passed very close to Cabo San Lucas early the next morning, and interaction with the high terrain of Baja California Sur caused the storm to weaken slightly; it made its first landfall near Punta Marquez with winds of 60mph (95km/h) around 12:00UTC, and its second landfall near Punta Abreojos early on September2 with winds of 45mph (70km/h). Lidia continued to weaken as it moved northwest, degenerating to a remnant low around 06:00UTC on September3 and dissipating twelve hours later.[110]
On September8, Atlantic Hurricane Katia made landfall in Mexico, dissipating on September9. However, its mid-level circulation survived, and eventually spawned an area of low pressure off the coast of Mexico. On September11, the system organized into Tropical Depression Fifteen-E.[111] It strengthened into a tropical storm at 00:00UTC on September13 and reached its initial peak intensity of 40mph with its pressure falling to 1003mb. However, the upgrade was not made operationally and the system weakened back to a tropical depression 12hours later without being named. During the next several days the depression slowly drifted westward and struggled to intensify as it was situated within a dry environment. Some models even predicted the depression would dissipate without ever reaching tropical storm strength again.[112] However, by 15:00UTC on September16, the system unexpectedly started to organize with a small area of deep convection developing near its low-level center, which allowed it to finally restrengthen into a tropical storm later that day, at which time it was given the name Otis.[113] Only marginal strengthening was forecast, but Otis unexpectedly rapidly intensified into a Category2 hurricane by 15:00UTC on September17, despite low ocean temperatures, dry air, and increased wind shear.[114] Otis continued to intensify into a Category3 major hurricane by 03:00UTC on September18, developing a well-defined eye with a diameter of 12mi (19km).[115] Twelve hours after developing a well-defined eye, however, Otis started weakening as quickly as it had intensified, and by 21:00 UTC on September 19, Otis had weakened back into a tropical storm with maximum sustained winds of only 45mph (70km/h).[116] After losing most of its deep convection due to low sea surface temperatures, Otis degenerated to a remnant low.[117][118]
On September9, the NHC mentioned the possibility for an area of low pressure to form south of Mexico over later days.[119] A trough of low pressure materialized the next day,[120] steadily organizing into a tropical depression near the southwestern coast of Mexico around 15:00UTC on September13. Despite forecasts of little or no intensification,[121] the newly formed cyclone intensified into Tropical Storm Max six hours later.[122] Quick intensification ensued as the storm improved in structure and developed a well-defined eye, prompting the NHC to upgrade Max to a hurricane around 12:00UTC on September14.[123] Max attained peak winds of 90mph (145km/h),[124] while making landfall on the coastline of Guerrero. The mountainous terrain of inland Mexico severely disrupted Max's circulation, causing it to degenerate into a remnant low by 09:00UTC on September15, dissipating over Mexico later that day.[125]
In preparation for Max, about 788 people evacuated to temporary shelters.[126] Throughout Guerrero, over 1,500 homes were inundated by floodwaters or damaged by strong winds that ripped off roofs. Over 100 trees were downed, mudslides and sinkholes closed several roads (including Mexican Federal Highway 200), and telephone service was cut. At the height of the storm, 126,503 Comisión Federal de Electricidad customers lost electricity. A bridge between Cruz Grande and Copala was severely damaged, and access to Juchitán de Zaragoza was severed due to a flooded highway. One of 17 rapidly-rising rivers swept away a residence and two neighbors who attempted to rescue the homeowner; one of the neighbors died, constituting one of two deaths attributed to the storm. At least 3,000 residents across five municipalities in Guerrero were stranded.[126][127] Waves of 10–16ft (3–5m) battered the coastline, where six ships were sunk.[128] Damage from the hurricane was estimated to be around US$13million.[129]
On September 10, the NHC started to monitor an area of low pressure — associated with the tropical wave that spawned Hurricane Irma in the Atlantic basin — well south of Manzanillo, Mexico.[130][131] The disturbance gradually organized during the following days and by 09:00UTC on September14 the system was noted to develop a well-defined center and spiral banding.[132] This led to the formation of Tropical Storm Norma, operationally skipping tropical depression status.[133] In post-season analysis, it was determined that Norma had formed as a tropical depression three hours earlier, and that it did not strengthen into a tropical storm until 12:00UTC.[131] The newly formed tropical storm continued to intensify at a steady pace while it moved slowly northward, becoming a Category 1 hurricane by 00:00UTC on September16 and reaching winds of 75mph (120km/h).[131] At this time warnings were being issued for the southern portions of the Baja California Peninsula as Norma was forecast to become a significant hurricane and make landfall in the area.[134] However, its broad circulation and the entrainment of dry air quickly became an impediment in doing so.[135] Norma then weakened back to a tropical storm at 12:00UTC later that day while becoming stationary, though a developing ridge over Mexico began to move the storm slowly towards the north.[131] Norma maintained its intensity the next day and continued being slowly steered by the ridge towards a northwesterly to west-northwesterly path, all tropical storm warnings were discontinued as Norma started to shift its track more to the west.[136] The cyclone continued weakening for several days as it slowly drifted to the west, until finally degenerating into a remnant low at 03:00UTC on September20.[131] The remnants of Norma persisted for a little over 2 days before they completely dissipated.[131]
During the week of September 18, the NHC began monitoring a tropical wave,[137] as it spawned a broad area of low pressure located offshore of the southwestern coast of Mexico.[138] The disturbance lacked any significant organization until September 23 at around 21:00UTC when the system was noted to developed surface winds of over 35mph (55km/h) becoming Tropical Depression Eighteen-E.[139] The depression organized into a tropical storm six hours later and was given the name Pilar, the sixteenth named storm of the annual Pacific hurricane season.[140] Thereafter, despite having a disorganized appearance on satellite, Pilar's winds increased in strength, and it reached its peak with sustained winds of 50mph (80km/h).[141] By 09:00UTC on September 24, Pilar continued to track north along the coast, with warnings being issued for the southwestern coast of Mexico.[142] However, early on September 25, these warnings were discontinued,[143] as Tropical Storm Pilar showed signs of weakening mainly due to land interaction, and was reduced to a tropical depression before ultimately dissipating at around 21:00UTC later that same day.[144] Although Pilar did not make landfall as a tropical cyclone, heavy rainfall was reported in Puerto Vallarta, Mexico, to the northeast of Islas Marías, and in other areas along the Mexican coastline.[145]
On October 3, the NHC noted a high chance of tropical development for an area of low pressure, to the south of Mexico.[146] The system increased in intensity and became Tropical Storm Ramon later on the same day.[147] Due to wind shear from a large anticyclone to its north, the storm did not intensify much further.[148] Although Ramon was forecast to linger over open waters as it moved westward, this did not occur and the system quickly grew disorganized.[149] Ramon weakened into a tropical depression on October 4, having lasted as a tropical storm only for 18 hours.[150] As it moved westward, Ramon continued to weaken, until it finally degenerated into a trough of low pressure by 00:00UTC the following day.[151] The National Hurricane Center issued its last advisory on the degenerate system at 09:00UTC, on October 5. The remnant low dissipated later that day.[152]
Late on October24, the NHC began to monitor the formation of an area of low pressure located south of eastern Central America.[153] The system quickly gained organization as it moved northwestwards,[154] and was declared Tropical Storm Selma at 09:00UTC on October27.[155] This marked only the second time that an Eastern Pacific tropical cyclone became a tropical storm east of 90°W, the other being Alma of 2008.[155] With the environment thought to be generally conducive to intensification, Selma was forecast to gain some strength before moving northwards into Central America. However, with wind shear stronger than expected,[156] this did not occur, and Selma never strengthened beyond minimal tropical storm status.[157] Eventually, at 12:00UTC on October28, Selma made landfall just southeast of San Salvador, El Salvador,[158] becoming the first Eastern Pacific tropical cyclone to make landfall anywhere in El Salvador.[159] Once over land, Selma weakened quickly, and degenerated into a post-tropical cyclone by 21:00UTC on October28. Selma's remnant dissipated overland within the next several hours.[160]
Heavy rains produced by Selma and a cold front resulted in flooding that killed seven people in Honduras. Dozens of landslides damaged homes and blocked roadways while 13rivers topped their banks. Approximately 38,000people required evacuation and more than 3,000homes were flooded as 13rivers topped their banks.[161] Rainfall extended into Nicaragua, causing floods that claimed another 10lives in areas recovering from Tropical Storm Nate two weeks prior.[162]
The following list of names was used for named storms that formed in the North Pacific Ocean east of 140°W during 2017.[163] This was the same list used for the 2011 season,[164] as no names were retired following that season.[165]
The usage of the name "Hilary" in July garnered some negative attention relating to former U.S. presidential candidate Hillary Clinton. People also took to Twitter to poke fun at the name and at Clinton with political jokes.[166]
For storms that form in the North Pacific from 140°W to the International Date Line, the names come from a series of four rotating lists. Names are used one after the other without regard to year, and when the bottom of one list is reached, the next named storm receives the name at the top of the next list.[163] No storms formed within the area in 2017. Named storms in the table above that crossed into the area during the season are noted (*).[167]
Season effects
This is a table of all of the storms that formed in the 2017 Pacific hurricane season. It includes their name, duration (within the basin), peak classification and intensities, areas affected, damage, and death totals. Deaths in parentheses are additional and indirect (an example of an indirect death would be a traffic accident), but were still related to that storm. Damage and deaths include totals while the storm was extratropical, a wave, or a low, and all of the damage figures are in 2017 USD.
↑ Hurricanes reaching Category3 (111 miles per hour or 179 kilometers per hour) and higher on the five-level Saffir–Simpson wind speed scale are considered major hurricanes.[1]
↑ All damage totals are valued as of 2017 and in United States dollars, unless otherwise noted.
↑ A major hurricane is a storm that ranks as Category3 or higher on the Saffir–Simpson scale.
↑ The total represents the sum of the squares of the maximum sustained wind speed (knots) for every (sub)tropical storm's intensity of over 33knots (38mph, 61km/h), divided by 10,000 while they are above that threshold; therefore, tropical depressions are not included.
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The 1993 Pacific hurricane season included more than double the average number of major hurricanes – Category 3 or stronger cyclones on the Saffir–Simpson scale. This activity was the result of an El Niño event, which is the main factor contributing to above-average activity across the Pacific basin. The season featured 15 named storms, 11 hurricanes, and 9 major hurricanes. While the number of named storms was near the long-term average, the number of hurricanes was above the average of 8, and the number of major hurricanes far exceeded the long-term average of 4. Seasonal activity began on May 17 and ended on November 8, within the confines of a traditional hurricane season which begins on May 15 in the East Pacific and June 1 in the Central Pacific. The season ends on November 30 in both basins. These dates conventionally delimit the period during each year when most tropical cyclones form.
The 2005 Atlantic hurricane season was an event in the annual tropical cyclone season in the north Atlantic Ocean. It was the second most active Atlantic hurricane season in recorded history, and the most extreme in the satellite era. Officially, the season began on June 1, 2005 and ended on November 30, 2005. These dates, adopted by convention, historically delimit the period in each year when most tropical systems form. The season's first storm, Tropical Storm Arlene, developed on June 8. The final storm, Tropical Storm Zeta, formed in late December and persisted until January 6, 2006. Zeta is only the second December Atlantic storm in recorded history to survive into January, joining Hurricane Alice in 1955.
The 2011 Pacific hurricane season was a below average season in terms of named storms, although it had an above average number of hurricanes and major hurricanes. During the season, 13 tropical depressions formed along with 11 tropical storms, 10 hurricanes and 6 major hurricanes. The season officially began on May 15 in the East Pacific Ocean, 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. The season's first cyclone, Hurricane Adrian formed on June 7, and the last, Hurricane Kenneth, dissipated on November 25.
The 2012 Pacific hurricane season was a moderately active Pacific hurricane season that saw an unusually high number of tropical cyclones pass west of the Baja California Peninsula. The season officially began on May 15 in the eastern Pacific Ocean, and on June 1 in the central Pacific (from 140°W to the International Date Line, north of the equator; they both ended on November 30. These dates conventionally delimit the period of each year when most tropical cyclones form in these regions of the Pacific Ocean. However, the formation of tropical cyclones is possible at any time of the year. This season's first system, Tropical Storm Aletta, formed on May 14, and the last, Tropical Storm Rosa, dissipated on November 3.
The 2014 Pacific hurricane season was one of the busiest and costliest Pacific hurricane seasons since the keeping of reliable records began in 1949. The season officially started on May 15 in the East Pacific Ocean, 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 these regions of the Pacific.
The 2016 Pacific hurricane season was tied as the fifth-most active Pacific hurricane season on record, alongside the 2014 season. Throughout the course of the year, a total of 22 named storms, 13 hurricanes and six major hurricanes were observed within the basin. Although the season was very active, it was considerably less active than the previous season, with large gaps of inactivity at the beginning and towards the end of the season. It officially started 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 these regions of the Pacific Ocean. However, tropical development is possible at any time of the year, as demonstrated by the formation of Hurricane Pali on January 7, the earliest Central Pacific tropical cyclone on record. After Pali, however, no tropical cyclones developed in either region until a short-lived depression on June 6. Also, there were no additional named storms until July 2, when Tropical Storm Agatha formed, becoming the latest first-named Eastern Pacific tropical storm since Tropical Storm Ava in 1969.
Hurricane Dennis lasted 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 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.
Tropical Storm Lidia was a large tropical cyclone that caused flooding in Baja California Peninsula and parts of western Mexico. The fourteenth tropical cyclone and twelfth named storm of the 2017 Pacific hurricane season, Lidia developed from a large area of disturbed weather west of the Pacific Coast of Mexico on August 31. The storm intensified while moving generally northward or northwestward, peaking with maximum sustained winds of 65 mph (105 km/h) later that day. On September 1, Lidia made landfall in Mexico near Puerto Chale, Baja California Sur, at peak intensity. The storm weakened while traversing the peninsula, ultimately emerging over the Pacific Ocean on September 3, where the storm degenerated into a remnant low. The system brought thunderstorms and wind gusts to Southern California, before dissipating on September 4.
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 were forecast to regenerate into a tropical cyclone after exiting land.
The 2019 Pacific hurricane season was an above average season which produced nineteen named storms, most of which were rather weak and short-lived. Only seven hurricanes formed, the fewest since 2010. The season officially began on May 15 in the East Pacific Ocean, 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. This season was one of the latest-starting Pacific hurricane seasons on record, with the first tropical cyclone, Hurricane Alvin, forming on June 25. The final system, Tropical Depression Twenty-One-E, dissipated on November 18.
The 2020 Pacific hurricane season was a near average Pacific hurricane season in terms of named storms, featuring 17, but well below average season for hurricanes and major hurricanes, with only 4 hurricanes and 3 major hurricanes forming. Additionally, no tropical cyclones formed in the Central Pacific basin for the first time since 2017. The season officially began on May 15 in the East Pacific Ocean, and on June 1 in the Central Pacific (from 140°W to the International Date Line, north of the equator; they both ended on November 30. These dates conventionally delimit the period of each year when most tropical cyclones form in the respective regions. However, the formation of tropical cyclones is possible at any time of the year, as illustrated in 2020 by the formation of the season's first system, Tropical Depression One-E, on April 25. This was the earliest formation of a tropical cyclone on record in the eastern Pacific basin proper. The final system of the season was Tropical Storm Polo, which dissipated on November 19.
The 2021 Pacific hurricane season was a moderately active Pacific hurricane season, with above-average activity in terms of number of named storms, but below-average activity in terms of major hurricanes, as 19 named storms, 8 hurricanes, and 2 major hurricanes formed in all. It also had a near-normal accumulated cyclone energy (ACE). The season officially began on May 15, 2021 in the Eastern Pacific Ocean, and on June 1, 2021, in the Central Pacific in the Northern Hemisphere. The season ended in both regions on November 30, 2021. These dates historically describe the period each year when most tropical cyclogenesis occurs in these regions of the Pacific and are adopted by convention. However, the formation of tropical cyclones is possible at any time of the year, as illustrated by the formation of Tropical Storm Andres on May 9, which was the earliest forming tropical storm on record in the Eastern Pacific. Conversely, 2021 was the second consecutive season in which no tropical cyclones formed in the Central Pacific.
The 2022 Pacific hurricane season was a slightly above average hurricane season in the eastern North Pacific basin, with nineteen named storms, ten hurricanes, and four major hurricanes. Two of the storms crossed into the basin from the Atlantic. In the central North Pacific basin, no tropical cyclones formed. The season officially began on May 15 in the eastern Pacific, and on June 1 in the central; both ended on November 30. These dates historically describe the period each year when most tropical cyclogenesis occurs in these regions of the Pacific and are adopted by convention.
The meteorological history of Hurricane Florence spanned 22 days from its inception on August 28, 2018, to its dissipation on September 18. Originating from a tropical wave over West Africa, Florence quickly organized upon its emergence over the Atlantic Ocean. Favorable atmospheric conditions enabled it to develop into a tropical depression on August 31 just south of the Cape Verde islands. Intensifying to a tropical storm the following day, Florence embarked on a west-northwest to northwest trajectory over open ocean. Initially being inhibited by increased wind shear and dry air, the small cyclone took advantage of a small area of low shear and warm waters. After achieving hurricane strength early on September 4, Florence underwent an unexpected period of rapid deepening through September 5, culminating with it becoming a Category 4 hurricane on the Saffir-Simpson scale. Thereafter, conditions again became unfavorable and the hurricane quickly diminished to a tropical storm on September 7.
Hurricane Douglas was a strong tropical cyclone that became the closest passing Pacific hurricane to the island of Oahu on record, surpassing the previous record held by Hurricane Dot in 1959. The eighth tropical cyclone, fifth named storm, first hurricane, and first major hurricane of the 2020 Pacific hurricane season, Douglas originated from a tropical wave which entered the basin in mid-July. Located in favorable conditions, the wave began to organize on July 19. It became a tropical depression on July 20 and a tropical storm the following day. After leveling off as a strong tropical storm due to dry air, Douglas began rapid intensification on July 23, becoming the season's first major hurricane the following day and peaking as a Category 4 hurricane. After moving into the Central Pacific basin, Douglas slowly weakened as it approached Hawaii. The storm later passed north of the main islands as a Category 1 hurricane, passing dangerously close to Oahu and Kauai, causing minimal damage, and resulting in no deaths or injuries. Douglas weakened to tropical storm status on July 28, as it moved away from Hawaii, before degenerating into a remnant low on July 29 and dissipating on the next day.
Hurricane Genevieve was a strong tropical cyclone that almost made landfall on the Baja California Peninsula in August 2020. Genevieve was the twelfth tropical cyclone, seventh named storm, third hurricane, and second major hurricane of the 2020 Pacific hurricane season. The cyclone formed from a tropical wave that the National Hurricane Center (NHC) first started monitoring on August 10. The wave merged with a trough of low pressure on August 13, and favorable conditions allowed the wave to intensify into Tropical Depression Twelve-E at 15:00 UTC. Just six hours later, the depression became a tropical storm and was given the name Genevieve. Genevieve quickly became a hurricane by August 17, and Genevieve began explosive intensification the next day. By 12:00 UTC on August 18, Genevieve reached its peak intensity as a Category 4 hurricane, with maximum 1-minute sustained winds of 130 mph and a minimum central pressure of 950 millibars (28 inHg). Genevieve began to weaken on the next day, possibly due to cooler waters caused by Hurricane Elida earlier that month. Genevieve weakened below tropical storm status around 18:00 UTC on August 20, as it passed close to Baja California Sur. Soon afterward, Genevieve began to lose its deep convection and became a post-tropical cyclone by 21:00 UTC on August 21, eventually dissipating off the coast of Southern California late on August 24.
The 2023 Pacific hurricane season was an active and destructive Pacific hurricane season. In the Eastern Pacific basin, 17 named storms formed; 10 of those became hurricanes, of which 8 strengthened into major hurricanes – double the seasonal average. In the Central Pacific basin, no tropical cyclones formed for the fourth consecutive season, though four entered into the basin from the east. Collectively, the season had an above-normal accumulated cyclone energy (ACE) value of approximately 168 units. This season saw the return of El Niño and its associated warmer sea surface temperatures in the basin, which fueled the rapid intensification of several powerful storms. It officially began on May 15, 2023 in the Eastern Pacific, and on June 1 in the Central; both ended on November 30. These dates, adopted by convention, historically describe the period in each year when most tropical cyclogenesis occurs in these regions of the Pacific.
The 2024 Pacific hurricane season is the current Pacific hurricane season in the Northern Hemisphere. It officially began on May 15 in the eastern Pacific basin and on June 1 in the central Pacific ; both will end on November 30. These dates, adopted by convention, historically describe the period in each year when most subtropical or tropical cyclogenesis occurs in these regions of the Pacific Ocean. For the third consecutive year, there were no pre-season tropical cyclones in either basin, and the season got off to the slowest start of any Pacific hurricane season on record in the satellite era. The first eastern Pacific tropical storm, Aletta, did not form until July 4. The first central Pacific tropical storm, Hone, formed on August 22, becoming the first named storm to develop in the basin since 2019.
Hurricane Enrique was a Category 1 Pacific hurricane that brought heavy rainfall and flooding to much of western Mexico in late June 2021. The fifth named storm and first hurricane of the 2021 Pacific hurricane season, Enrique developed from a tropical wave the entered the Pacific Ocean off the coast of Nicaragua on June 22. In an environment conducive for intensification, the disturbance moved west-northwestward and developed into a tropical storm by 6:00 UTC on June 25, as it was already producing winds of 40 mph (65 km/h), and received the name Enrique. Enrique strengthened steadily within an environment of warm waters and low-to-moderate wind shear while continuing its northwestward motion. By 12:00 UTC on June 26, Enrique had intensified into a Category 1 hurricane as the storm turned more northwestward. Nearing the coast of Mexico, Enrique reached its peak intensity around 6:00 UTC the following day, with maximum sustained winds of 90 mph (150 km/h) and a minimum barometric pressure of 972 mbar (28.7 inHg). Enrique, passing closely offshore west-central Mexico, maintained its intensity for another 24 hours as it turned northward toward the Gulf of California. Turning back to the northwest on June 28, increasing wind shear and dry air caused the hurricane to weaken. Enrique dropped to tropical storm status at 18:00 UTC that day, and further weakened to a tropical depression on June 30 just to the northeast of Baja California. The depression was absorbed into a larger low pressure area to the southeast later that day.
↑ Dorst Neal. When is hurricane season? (Report). Atlantic Oceanographic and Meteorological Laboratory. Archived from the original on 6 December 2010. Retrieved November 25, 2010.
↑ Christopher W. Landsea; Nelsie A. Ramos (July 21, 2017). Tropical Storm Greg Discussion Number 19 (Report). Miami, Florida: National Hurricane Center. Retrieved July 21, 2017.
↑ Christopher W. Landsea; Nelsie Ramos (August 7, 2017). Graphical Tropical Weather Outlook (Report). Miami, Florida: National Hurricane Center. Retrieved August 22, 2017.
↑ Christopher W. Landsea; Nelsie Ramos (September 9, 2017). "Graphical Tropical Weather Outlook". Miami, Florida: National Hurricane Center. Retrieved September 16, 2017.
↑ David A. Zelinsky; Matthew Onderlinde (September 10, 2017). "Graphical Tropical Weather Outlook". Miami, Florida: National Hurricane Center. Retrieved September 16, 2017.
↑ Lixion A. Avila (September 14, 2017). Hurricane Max Discussion Number 5 (Report). Miami, Florida: National Hurricane Center. Retrieved September 16, 2017.
↑ Lixion A. Avila (September 15, 2017). Remnants of Max Discussion Number 9 (Report). Miami, Florida: National Hurricane Center. Retrieved September 16, 2017.
↑ Christopher Landsea (September 10, 2017). Graphical Tropical Weather Outlook (Report). Miami, Florida: National Hurricane Center. Retrieved September 27, 2017.
1 2 3 4 5 6 John L. Beven II; Christopher Landsea (March 12, 2018). HURRICANE NORMA (EP172017)(PDF) (Report). Tropical Cyclone Report. Miami, Florida: National Hurricane Center. Retrieved April 3, 2018.
↑ Lixion A. Avila (September 15, 2017). Hurricane Norma Advisory Number 4 (Report). Miami, Florida: National Hurricane Center. Retrieved September 27, 2017.
↑ Daniel P. Brown (September 16, 2017). Hurricane Norma Discussion Number 7 (Report). Miami, Florida: National Hurricane Center. Retrieved September 27, 2017.
↑ Christopher Landsea (September 25, 2017). Remnants of Pilar Advisory Number 9 (Report). Miami, Florida: National Hurricane Center. Retrieved September 25, 2017.
↑ Daniel P. Brown (December 11, 2017). Tropical Storm Ramon(PDF) (Report). Tropical Cyclone Report. Miami, Florida: National Hurricane Center. Retrieved May 9, 2018.
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