|Tropical Storm (SSHWS/NWS)|
|Formed||August 4, 2018|
|Dissipated||August 7, 2018|
|Highest winds|| 1-minute sustained:65 mph (100 km/h)|
|Lowest pressure||998 mbar (hPa); 29.47 inHg|
|Damage||≥ $737,000 (2018 USD)|
|Areas affected||Western Mexico|
|Part of the 2018 Pacific hurricane season|
Tropical Storm Ileana was a tropical cyclone that affected Western Mexico, causing multiple deaths and flooding. The ninth named storm of the 2018 Pacific hurricane season, Ileana originated from a tropical wave that the National Hurricane Center began monitoring on July 26 as it left the west coast of Africa. The wave travelled across the Atlantic Ocean with no thunderstorm activity, before crossing into the Eastern Pacific Ocean on August 4. The disturbance quickly and unexpectedly organized into a tropical depression later in the day. Initially, the depression was well defined, but it soon degraded due to unfavorable conditions. It began to strengthen on August 5, becoming Tropical Storm Ileana. On August 6, Ileana peaked with winds of 65 mph (100 km/h) and a pressure of 998 mbar (29.47 inHg). Ileana began to develop an eyewall structure soon after, but became intertwined with nearby Hurricane John. John disrupted Ileana and ultimately absorbed it on August 7.
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".
Mexico, officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatemala, Belize, and the Caribbean Sea; and to the east by the Gulf of Mexico. Covering almost 2,000,000 square kilometres (770,000 sq mi), the nation is the fifth largest country in the Americas by total area and the 13th largest independent state in the world. With an estimated population of over 120 million people, the country is the eleventh most populous state and the most populous Spanish-speaking state in the world, while being the second most populous nation in Latin America after Brazil. Mexico is a federation comprising 31 states and Mexico City, a special federal entity that is also the capital city and its most populous city. Other metropolises in the state include Guadalajara, Monterrey, Puebla, Toluca, Tijuana and León.
The 2018 Pacific hurricane season produced the highest accumulated cyclone energy (ACE) value on record in the Eastern Pacific basin. 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.
Ileana prompted the issuance of multiple watches and warnings along the coast of Baja California Sur and Western Mexico. Ileana caused a total of four deaths in Guerrero, with two occurring in Chilpancingo and the remainder in Acapulco. Additionally, Ileana caused flooding in the Mexican states of Oaxaca, Guerrero, and Mexico.
Tropical cyclone warnings and watches are two levels of alert issued by national weather forecasting bodies to coastal areas threatened by the imminent approach of a tropical cyclone of tropical storm or hurricane intensity. They are notices to the local population and civil authorities to make appropriate preparation for the cyclone, including evacuation of vulnerable areas where necessary. It is important that interests throughout the area of an alert make preparations to protect life and property, and do not disregard it on the strength of the detailed forecast track. Tropical cyclones are not points, and forecasting their track remains an uncertain science.
Baja California Sur, officially the Estado Libre y Soberano de Baja California Sur, is the second-smallest Mexican state by population and the 31st admitted state of the 31 states which, with Mexico City, make up the 32 Federal Entities of Mexico.
Guerrero, officially the Free and Sovereign State of Guerrero, is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided in 81 municipalities and its capital city is Chilpancingo and its largest city is Acapulco.
The origins of Ileana can be traced back to a tropical wave that the National Hurricane Center (NHC) began monitoring on July 26 as it departed from the west coast of Africa. The wave had virtually no convection as it crossed over the Atlantic. Once the wave entered the Eastern Pacific Ocean early on August 4, thunderstorm and convective activity rapidly increased.At 17:00 UTC, the NHC raised its development chances to 50% after satellite imagery indicated an area of low pressure had formed a few hundred miles south of the Gulf of Tehuantepec and was showing signs of organization. At 18:00 UTC, the system was designated as a tropical depression. Around that time, the NHC noted the depression had a well defined low pressure center and a distinct, curved band of deep convection. Six hours later, the structure of the depression had degraded due to wind shear from the north. The low-level center had become exposed in the northwest and convection in the east and south had decreased. Despite the disruptive wind shear, the depression then began to strengthen, reaching tropical storm status on August 5, afterwhich it was assigned the name Ileana. At that time, Ileana had a fairly symmetrical shape and a central dense overcast-like feature had developed over the system.
Tropical waves, easterly waves, or tropical easterly waves, also known as African easterly waves in the Atlantic region, are a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, which moves from east to west across the tropics, causing areas of cloudiness and thunderstorms. West-moving waves can also form from the tail end of frontal zones in the subtropics and tropics, and may be referred to as easterly waves, but these waves are not properly called tropical waves; they are a form of inverted trough sharing many characteristics with fully tropical waves. All tropical waves form in the easterly flow along the equatorward side of the subtropical ridge or belt of high pressure which lies north and south of the Intertropical Convergence Zone (ITCZ). Tropical waves are generally carried westward by the prevailing easterly winds along the tropics and subtropics near the equator. They can lead to the formation of tropical cyclones in the north Atlantic and northeastern Pacific basins. A tropical wave study is aided by Hovmöller diagrams, a graph of meteorological data.
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.
Africa is the world's second largest and second most-populous continent, being behind Asia in both categories. At about 30.3 million km2 including adjacent islands, it covers 6% of Earth's total surface area and 20% of its land area. With 1.2 billion people as of 2016, it accounts for about 16% of the world's human population. The continent is surrounded by the Mediterranean Sea to the north, the Isthmus of Suez and the Red Sea to the northeast, the Indian Ocean to the southeast and the Atlantic Ocean to the west. The continent includes Madagascar and various archipelagos. It contains 54 fully recognised sovereign states (countries), nine territories and two de facto independent states with limited or no recognition. The majority of the continent and its countries are in the Northern Hemisphere, with a substantial portion and number of countries in the Southern Hemisphere.
Ileana continued to strengthen over the next day after entering an area with sea surface temperatures of 30 to 31 °C (86 to 88 °F). On August 6 at 12:00 UTC, Ileana reached peak intensity with maximum sustained winds of 65 mph (100 km/h) and a minimum central pressure of 998 mbar (29.47 inHg). Around the same time, the NHC reported that Ileana had strong deep convection with cloud temperatures of −85 to −90 °C (−121 to −130 °F). Additionally, a banded eye feature had developed within the central dense overcast. Soon after, microwave imagery and Acapulco radar showed the emergence of an eyewall structure at the mid-levels of the system. By 21:00 UTC, Ileana was becoming increasingly intertwined in the outer bands of Hurricane John to the west as the two systems began to experience the Fujiwhara effect. At 12:00 UTC on August 7, Ileana was completely absorbed by John.
The maximum sustained wind associated with a tropical cyclone is a common indicator of the intensity of the storm. Within a mature tropical cyclone, it is found within the eyewall at a distance defined as the radius of maximum wind, or RMW. Unlike gusts, the value of these winds are determined via their sampling and averaging the sampled results over a period of time. Wind measuring has been standardized globally to reflect the winds at 10 metres (33 ft) above the Earth's surface, and the maximum sustained wind represents the highest average wind over either a one-minute (US) or ten-minute time span, anywhere within the tropical cyclone. Surface winds are highly variable due to friction between the atmosphere and the Earth's surface, as well as near hills and mountains over land.
Acapulco de Juárez, commonly called Acapulco, is a city, municipality and major seaport in the state of Guerrero on the Pacific coast of Mexico, 380 kilometres (240 mi) south of Mexico City. Acapulco is located on a deep, semicircular bay and has been a port since the early colonial period of Mexico's history. It is a port of call for shipping and cruise lines running between Panama and San Francisco, California, United States. The city of Acapulco is the largest in the state, far larger than the state capital Chilpancingo. Acapulco is also Mexico's largest beach and balneario resort city.
The Fujiwhara effect, sometimes referred to as the Fujiwara effect, Fujiw(h)ara interaction or binary interaction, is a phenomenon that occurs when two nearby cyclonic vortices orbit each other and close the distance between the circulations of their corresponding low-pressure areas. The effect is named after Sakuhei Fujiwhara, the Japanese meteorologist who initially described the effect. Binary interaction of smaller circulations can cause the development of a larger cyclone, or cause two cyclones to merge into one. Extratropical cyclones typically engage in binary interaction when within 2,000 kilometres (1,200 mi) of one another, while tropical cyclones typically interact within 1,400 kilometres (870 mi) of each other.
As a precautionary measure, the Government of Mexico issued a Tropical Storm Watch for the coast of Mexico from Lazaro Cardenas to Cabo Corrientes on August 5 at 22:40 UTC.At 03:00 UTC, the watch was upgraded to a Tropical Storm Warning. Six hours later, the Government of Mexico issued a Hurricane Watch for Punta San Telmo to Playa Perula and a Tropical Storm Watch was also issued for the southern tip of Baja California Sur from Los Barilles to Todo Santos. At 12:00 UTC, the Tropical Storm Warning was extended eastward to include Lazaro Cardenas to Tecpan de Galeana. All watches and warnings were gradually discontinued after Ileana was no longer forecast to strengthen.
Cabo Corrientes is a cape on the Pacific coast of the Mexican state of Jalisco. It marks the southernmost point of the Bahía de Banderas, upon which the port and resort city of Puerto Vallarta stands. The municipality in which the cape lies is also called Cabo Corrientes.
In the Mexican state of Guerrero, Ileana caused a total of four deaths. On August 5, the body of 35-year-old man was discovered in the Huacapa River in Chilpancingo. The man had reportedly been pushing a car when a strong current pulled him down to the river where he drowned. Additionally, an 8-year-old and a 15-year-old fell into the Laguna de Tres Palos in Acapulco and drowned after their fishing boat capsized. There, multiple power outages occurred due to a fallen tree. A peak rainfall total of 3.54 inches (90 mm) was recorded at the Acapulco International Airport. The lowest rainfall total in the area, 0.46 inches (11.75 mm), was recorded at Renacimiento. In the municipality of Coyuca de Benítez, at least 20 homes were inundated and numerous streets were flooded. Rip currents along the coast of Chilpancingo resulted in the death of a tourist at La Condesa beach. He was rescued by lifeguards, but later died despite receiving medical treatment. In the municipality of Santiago Choapam in Oaxaca, heavy rains from Ileana caused a landslide that left a house buried. While in the Mexican state of Chiapas, Ileana caused another four deaths. In Jiquipilas on August 6, a car containing 18 individuals was dragged away by the current while attempting to cross a flooded bridge. Three children and one adult were later found dead. In Michoacán, the state required MX$13.6 million (US$737,000) to repair the road and highway.
Chilpancingo de los Bravo is the capital and second-largest city of the state of Guerrero, Mexico. In 2010 it had a population of 187,251 people. The municipality has an area of 2,338.4 km2 (902.9 sq mi) in the south-central part of the state, situated in the Sierra Madre del Sur, on the bank of the Huacapa River. The city is on Mexican Federal Highway 95 which connects Acapulco to Mexico City. It is served by Chilpancingo National Airport, which is one of the five airports in the state.
Acapulco International Airport, officially General Juan N. Álvarez International Airport, is the main airport of Acapulco, Guerrero, Mexico, located 26 km from the city.
Coyuca de Benítez is one of the 81 municipalities of Guerrero, in south-western Mexico. The municipal seat lies at Coyuca de Benítez. The municipality covers an area of 1,602.9 km².
In the state of Mexico, heavy rains from Ileana caused severe flooding. The Anillo Periférico and several other roads in Mexico City experienced flooding. As a result of the rains, the Mexico City Metro (STC) implemented safety measures for several of its lines.The San Jerónimo Canal overflowed in the El Rosal neighborhood in Magdalena Contreras. Additionally, two trees fell and total of 33 structures were inundated throughout Mexico City. In the Huixquilucan municipality, a sewage pipe overflowed and two homes were flooded.
The 2007 Pacific hurricane season was a below-average Pacific hurricane season, featuring one major hurricane. The season officially started on May 15 in the eastern Pacific and on June 1 in the central Pacific, and ended on November 30; these dates conventionally delimit the period during which most tropical cyclones form in the region. The first tropical cyclone of the season, Alvin, developed on May 27, while the final system of the year, Kiko, dissipated on October 23. Due to unusually strong wind shear, activity fell short of the long-term average, with a total of 11 named storms, 4 hurricanes, and 1 major hurricane. At the time, 2007 featured the second-lowest value of the Accumulated cyclone energy (ACE) index since reliable records began in 1971. Two tropical cyclones – Cosme and Flossie – crossed into the central Pacific basin during the year, activity below the average of 4 to 5 systems.
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 started on May 15 in the eastern Pacific, and on June 1 in the central Pacific, and ended on November 30; these dates conventionally delimit the period during which most tropical cyclones form in the northeastern Pacific Ocean. However, with the formation of Tropical Storm Aletta on May 14 the season slightly exceeded these bounds.
Tropical Storm Norman was a weak tropical cyclone that brought heavy rainfall to southwestern Mexico in October 2006. The twelfth named storm of the 2006 Pacific hurricane season, Norman developed on October 9 from a tropical wave well to the southwest of Mexico. Unfavorable conditions quickly encountered the system, and within two days of forming, Norman dissipated as its remnants turned to the east. Thunderstorms gradually increased again, as it interacted with a disturbance to its east, and on October 15 the cyclone regenerated just off the coast of Mexico. The center became disorganized and quickly dissipated, bringing a large area of moisture which dropped up to 6 inches (150 mm) of rainfall to southwestern Mexico. Rainfall from the storm flooded about 150 houses, of which 20 were destroyed. One person was injured, and initially there were reports of two people missing due to the storm; however, it was not later confirmed.
Tropical Storm Julio in 2002 was a weak and short-lived tropical storm that made landfall along the southern Mexican coast. An area of convection organized into a tropical depression on September 25. Initially forecast to stay offshore, the depression headed northward and strengthened into a tropical storm that same day. Julio turned to the northwest and peaked as a minimal tropical storm just before landfall near Lázaro Cárdenas, on September 26. The storm soon weakened into a tropical depression and later on September 26, it rapidly dissipated over Mexico.
Tropical Storm Odile was a late season tropical storm that formed during the 2008 Pacific hurricane season and affected parts of southern Mexico. A tropical depression formed on October 8, and became Tropical Storm Odile 18 hours later. The storm paralleled the south coast of Mexico, with the center located only several miles offshore. After peaking in intensity, increasing southeasterly vertical wind shear induced a trend of rapid weakening on the storm. Correspondingly, Odile was downgraded to a tropical depression early on 12 October, subsequently degenerating into a remnant low about 55 mi (85 km) south of Manzanillo, Colima. From thereon, the low proceeded slowly south-southwestward before dissipating on October 13. Since Odile stayed at sea, its effects along coastlines were limited. The most notable damages were caused by flooding along the southern coast of Mexico, mostly in Chiapas, Oaxaca, Guerrero and Michoacán. The exact amount of damage, however, remains unknown, and no fatalities were reported as a result of the storm.
Tropical Storm Carlos was the first of five tropical cyclones to make landfall during the 2003 Pacific hurricane season. It formed on June 26 from a tropical wave to the south of Mexico. It quickly strengthened as it approached the coast, and early on June 27 Carlos moved ashore in Oaxaca with winds of 65 mph (100 km/h). The storm rapidly deteriorated to a remnant low, which persisted until dissipating on June 29. Carlos brought heavy rainfall to portions of southern Mexico, peaking at 337 mm (13.3 in) in two locations in Guerrero. Throughout its path, the storm damaged about 30,000 houses, with a monetary damage total of 86.7 million pesos. At least nine people were killed throughout the country, seven due to mudslides and two from river flooding; there was also a report of two missing fishermen.
The 2013 Pacific hurricane season was the costliest Pacific hurricane season on record, with a total of about $4.2 billion in damages. The season produced above normal activity; however, the majority of the storms were weak. The season officially began on May 15, 2013 in the Eastern Pacific and started on June 1, 2013 in the Central Pacific. Both ended on November 30, 2013. These dates conventionally delimit the period of each year when most tropical cyclones form in the eastern Pacific basin. However, the formation of a storm is possible at any time.
Hurricane Beatriz was a Category 1 hurricane that killed four people after brushing the western coast of Mexico in June 2011. Originating from an area of disturbed weather on June 19, several hundred miles south of Mexico, Beatriz gradually intensified. Gaining latitude, the system became increasingly organized and reached hurricane status on the evening of June 20. The following morning, Beatriz attained winds of 90 mph (150 km/h) as it passed roughly 15 mi (20 km) of Mexico. Due to its interaction with land, the hurricane abruptly weakened hours later. Early on June 22, Beatriz dissipated over open waters. Prior to Beatriz's arrival in Mexico, hurricane watches and warnings were issued for coastal areas. Hundreds of shelters opened across the states of Colima and Guerrero. Heavy rains from the storm triggered significant flooding along the Sabana River in Acapulco, killing four people. However, the overall effects of Beatriz were limited and the rains were largely beneficial in mitigating a severe drought.
Hurricane Adrian was an intense, albeit short-lived early-season category 4 hurricane that took part during the 2011 Pacific hurricane season. Adrian originated from an area of disturbed weather which had developed during the course of early June, off the Pacific coast of Mexico. On June 7, it acquired a sufficiently organized structure with deep convection to be classified as a tropical cyclone, and the National Hurricane Center (NHC) designated it as Tropical Depression One-E, the first one of 2011. It further strengthened to be upgraded into a tropical storm later that day. Adrian moved rather slowly; briefly recurving northward after being caught in the steering winds. After steady intensification, it was upgraded into a hurricane on June 9. The storm subsequently entered a phase of rapid intensification, developing a distinct eye with good outflow in all quadrants. Followed by this period of rapid intensification, it obtained sustained winds fast enough to be considered a major hurricane and reached its peak intensity as a category 4 hurricane that evening.
The 2012 Pacific hurricane season was an above-average year in which seventeen named storms formed. The hurricane season officially began on May 15 with the formation of Tropical Storm Aletta in the East Pacific—defined as the region east of 140°W—and on June 1 in the central Pacific—defined as the region west of 140°W to the International Date Line—and ended on November 30 in both basins. These dates conventionally delimit the period during each year when most tropical cyclones form. The final cyclone of the year, Tropical Storm Rosa, dissipated on November 3.
Tropical Storm Barry was a weak and short-lived tropical cyclone that brought heavy rains to parts of Central America and Mexico in June 2013. Barry originated from a tropical wave that developed in the southern Caribbean Sea. The wave tracked northwestward and began to develop in marginally favorable conditions. On June 17, the disturbance was upgraded to Tropical Depression Two by the National Hurricane Center. Due to its close proximity to land, the system failed to intensify before crossing the southern Yucatán Peninsula. The depression emerged over the Bay of Campeche late on June 18 and became increasingly organized. During the afternoon of June 19, data from Hurricane Hunters revealed the system had intensified into a tropical storm. The newly named Barry attained peak winds of 45 mph (75 km/h) before making landfall in Veracruz, Mexico on June 20. Once onshore, the storm quickly weakened and degenerated into a remnant low that night.
Hurricane Raymond was the only major hurricane in the eastern Pacific in 2013 and briefly threatened the southwestern coast of Mexico before recurving back out to sea. The seventeenth named storm and eighth hurricane of the annual cyclone season, Raymond developed from a tropical wave on October 20 south of Acapulco, Mexico. Within favorable conditions for tropical cyclone development, Raymond quickly intensified, attaining tropical storm intensity and later hurricane intensity within a day of cyclogenesis. On October 21, the hurricane reached its peak intensity with winds of 125 mph (205 km/h). A blocking ridge forced the hurricane to the southwest, while at the same time Raymond began to quickly weaken due to wind shear. The following day, the tropical cyclone weakened to tropical storm status. After tracking westward, Raymond reentered more favorable conditions, allowing it to intensify back to hurricane strength on October 27 while curving northward. The hurricane reached a secondary peak intensity with winds of 105 mph (165 km/h) several hours later. Deteriorating atmospheric conditions resulted in Raymond weakening for a final time, and on October 30, the National Hurricane Center (NHC) declared the tropical cyclone to have dissipated.
Hurricane Cosme caused flooding along the Pacific coast of Mexico in June 2013. The third named tropical cyclone of the 2013 Pacific hurricane season, the storm system formed from a tropical wave south of Manzanillo, Colima, on June 23. The cyclone intensified into a tropical storm on June 24, and soon after strengthened into a hurricane on June 25. Early the following day, Cosme attained its peak intensity as a Category 1 hurricane on the Saffir–Simpson scale with maximum sustained winds of 85 mph (140 km/h) and a minimum barometric pressure of 980 mbar. However, Cosme then began to encounter stable air and lower sea surface temperatures, causing the system to weaken to a tropical storm late on June 26. The system continued to weaken and degenerated into a remnant low pressure surface trough about 690 mi (1,110 km) west-southwest of Cabo San Lucas, Mexico, on June 27. The remnants persisted until dissipating well east-southeast of the Hawaiian Islands on July 1.
The 2014 Pacific hurricane season was an event in the annual cycle of tropical cyclone formation. It officially began on May 15 in the eastern Pacific—defined as the region east of 140°W—and began on June 1 in the central Pacific, defined as the region west of 140°W to the International Date Line; both ended on November 30.
Hurricane Marty was a tropical cyclone that produced heavy rains and flooding in several states in Southwestern and Western Mexico. The twentieth named storm and twelfth hurricane of the annual hurricane season, Marty developed from a tropical wave on September 26, 2015 to the southwest of Acapulco, Guerrero, in Mexico. Initially a tropical depression, the system strengthened into a tropical storm early on the following day. Due to favorable atmospheric conditions, Marty continued to intensify, but wind shear sharply increased as the storm approached a large mid- to upper-level trough. Despite this, the cyclone deepened further, becoming a hurricane on September 28 and peaking with sustained winds of 80 mph (130 km/h) shortly thereafter. Wind shear quickly took its toll on the hurricane, weakening it to a tropical storm early on September 29. About 24 hours later, Marty degenerated into a post-tropical low pressure area offshore Guerrero. The low further degenerated into a trough later on September 30, and eventually dissipated on October 4.
Tropical Storm Carlotta was a tropical cyclone that caused flooding in southwestern Mexico. Carlotta formed as the result of a breakdown in the Intertropical Convergence Zone to the south of Mexico. On June 12, the National Hurricane Center (NHC) reported that a broad area of low pressure had formed several hundred miles south of southeastern Mexico. The NHC continued to track the disturbance over the next couple of days as it drifted northward. After having increased in organization, the system was designated as a tropical depression on June 14. Late on the next day, the system strengthened into a tropical storm, after which it was named Carlotta. On June 16, Carlotta slowed down and unexpectedly stalled within a favorable environment, which led to more intensification than originally anticipated. Early on June 17, Carlotta reached peak intensity with maximum sustained winds of 65 mph and a minimum central pressure of 997 mbar. Soon after, Carlotta began to interact with land and experience wind shear, which resulted in the system weakening to tropical depression status later in the day. Carlotta weakened to a remnant low early on June 19 and dissipated several hours later.
Hurricane Olivia was the first tropical cyclone to make landfall on Maui and Lanai in recorded history. The fifteenth named storm, ninth hurricane, and sixth major hurricane of the 2018 Pacific hurricane season, Olivia formed southwest of Mexico on September 1. The depression slowly organized and strengthened into Tropical Storm Olivia on the next day. Olivia then began a period of rapid intensification on September 3, reaching its initial peak on September 5. Soon after, Olivia began a weakening trend, before re-intensifying on September 6. On the next day, Olivia peaked as a Category 4 hurricane, with winds of 130 mph and a minimum central pressure of 951 mbar. Six hours later, Olivia began another weakening trend that resulted in the hurricane being downgraded to Category 1 status on September 8, east of the 140th meridian west. On September 9, Olivia entered the Central Pacific Basin. Over the next couple of days, Olivia prompted the issuance of Tropical Storm Watches and Warnings for Hawaii County, Oahu, Maui County, and Kauai County. Olivia weakened into a tropical storm on September 11, before making brief landfalls in northwest Maui and Lanai on the next day, becoming the first tropical cyclone to impact the islands in recorded history. Tropical storm-force winds mainly affected Maui County and Oahu. Torrential rains affected the same area from September 11 to 13, causing flash flooding. Olivia caused a total of US$25 million in damages. Olivia was downgraded to a tropical depression on September 13 while continuing to head west. Due to wind shear disrupting Olivia's convection, the system weakened into a remnant low on September 14. Olivia crossed into the West Pacific Basin on September 19 as a remnant low, before dissipating later that day.
Hurricane Rosa was the first tropical cyclone to make landfall in the Mexican state of Baja California since Nora in 1997. The seventeenth named storm, tenth hurricane, and seventh major hurricane of the 2018 Pacific hurricane season, Rosa originated from a broad area of low pressure that the National Hurricane Center began monitoring on September 22. The disturbance moved westward and then west-northwestward for a few days, before developing into a tropical depression on September 25. Later that day, the depression strengthened into Tropical Storm Rosa. One day later, Rosa became a hurricane. On September 27, Rosa began a period of rapid intensification, ultimately peaking as a Category 4 hurricane with maximum sustained winds of 150 mph and a minimum central pressure of 936 mbar on the next day. Over the next couple of days, Rosa turned towards the northeast. By September 29, Rosa had weakened into a Category 2 hurricane due to ongoing structural changes and less favorable conditions. Later on the same day, Rosa re-intensified slightly. On September 30, Rosa resumed weakening as its core structure eroded. Early on October 1, Rosa weakened into a tropical storm. On October 2, Rosa weakened to a tropical depression and made landfall in Baja California. Later in the day, Rosa's remnants crossed into the Gulf of California, with its surface and mid-level remnants later separating entirely. The mid-level remnants of Rosa continued to travel north, reaching northeast Arizona late in the day. On October 3, Rosa's remnants were absorbed into an upper-level low situated off the coast of California.
Tropical Storm Vicente was an unusually small tropical cyclone that made landfall as a tropical depression in the Mexican state of Michoacán on October 23, 2018, causing deadly mudslides. The twenty-first named storm of the 2018 Pacific hurricane season, Vicente originated from a trough of low pressure that formed within a large area of disturbed weather near Central America early on October 19. Around midday, the disturbance organized into a tropical depression, which prompted the National Hurricane Center to begin issuing advisories. Later in day, the depression strengthened into a tropical storm and was assigned the name Vicente. Despite having only been a weak tropical storm, Vicente developed an intermittent eye-like feature. Unfavorable conditions prevented strengthening until late on October 20. At that time, Vicente peaked with maximum sustained winds of 50 mph and a minimum central pressure of 1002 mbar. A day later, Vicente began to weaken due increasing wind shear before slightly restrengthening early on October 22. On October 23, Vicente weakened into a tropical depression. Later in the day, Vicente degenerated into a remnant low after making landfall in southwestern Mexico, before dissipating soon afterward.
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