|Category 4 major hurricane (SSHWS/NWS)|
|Formed||September 25, 2018|
|Dissipated||October 3, 2018|
|( Remnant low after October 2)|
|Highest winds|| 1-minute sustained:150 mph (240 km/h)|
|Lowest pressure||936 mbar (hPa); 27.64 inHg|
|Damage||$50.5 million (2018 USD)|
|Areas affected||Baja California Peninsula, Northwestern Mexico, Southwestern United States|
|Part of the 2018 Pacific hurricane season|
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 (240 km/h) and a minimum central pressure of 936 mbar (27.64 inHg) 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.
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".
Baja California, officially the Free and Sovereign State of Baja California, is a state in Mexico. It is the northernmost and westernmost of the 32 Federal Entities of Mexico. Before becoming a state in 1952, the area was known as the North Territory of Baja California. It has an area of 70,113 km2 (27,071 sq mi), or 3.57% of the land mass of Mexico and comprises the northern half of the Baja California Peninsula, north of the 28th parallel, plus oceanic Guadalupe Island. The mainland portion of the state is bordered on the west by the Pacific Ocean, on the east by Sonora, the U.S. state of Arizona, and the Gulf of California, and on the south by Baja California Sur. Its northern limit is the U.S. state of California.
Hurricane Nora was only the third tropical cyclone on record to reach Arizona as a tropical storm, and one of the rare cyclones to make landfall in Baja California. Nora was the fourteenth named tropical cyclone and seventh hurricane of the 1997 Pacific hurricane season. The September storm formed off the Pacific coast of Mexico, and aided by waters warmed by the 1997–98 El Niño event, eventually peaked at Category 4 intensity on the Saffir–Simpson hurricane scale.
Rosa prompted the issuance of tropical storm watches and warnings along the coast of Baja California as well as various flood related watches and warnings throughout the Southwestern United States. Rainfall from Rosa affected a large geographical area, due to the remnants having split apart in the Gulf of California. Rosa caused significant flooding throughout northwestern Mexico, which has resulted in the deaths of one person. Rosa also caused flash-flooding in Arizona, with several inches of rain falling in areas, which indirectly resulted in the deaths of two individuals. Additionally, remnant moisture from Rosa led to rainfall throughout the Southwestern United States. Flood damage from Rosa totaled about US$50.5 million.
The Southwestern United States, also known as the American Southwest, is the informal name for a region of the western United States. Definitions of the region's boundaries vary a great deal and have never been standardized, though many boundaries have been proposed. For example, one definition includes the stretch from the Mojave Desert in California to Carlsbad, New Mexico, and from the Mexico–United States border to the southern areas of Colorado, Utah, and Nevada. The largest metropolitan areas are centered around Phoenix, Las Vegas, Tucson, Albuquerque, and El Paso. Those five metropolitan areas have an estimated total population of more than 9.6 million as of 2017, with nearly 60 percent of them living in the two Arizona cities—Phoenix and Tucson.
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 tenth 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 United States dollar is the official currency of the United States and its territories per the United States Constitution since 1792. In practice, the dollar is divided into 100 smaller cent (¢) units, but is occasionally divided into 1000 mills (₥) for accounting. The circulating paper money consists of Federal Reserve Notes that are denominated in United States dollars.
Hurricane Rosa originated from a vigorous tropical wave that departed from the west coast of Africa on September 6. The wave spawned Hurricane Helene on September 7,and then travelled across the tropical Atlantic with minimal convective activity. On September 19, the National Hurricane Center (NHC) began monitoring the wave for tropical development, anticipating that an area of low pressure would form a few hundred miles south of the Gulf of Tehuantepec over the weekend. On September 22, a broad area of low pressure formed approximately 200 mi (320 km) south of Mexico. The NHC continued to track the disturbance for a few more days as it moved westward to west-northwestward. On September 25 at 06:00 UTC, the NHC reported that a tropical depression had formed approximately 350 mi (565 km) south-southwest of Manzanillo, Mexico. Around that time, the NHC stated that the system had a well defined center and deep convection that was increasing in both coverage and intensity. Additionally, the depression was located in an environment with warm sea surface temperatures and minimal vertical wind shear. Six hours later, the depression strengthened into a tropical storm and was assigned the name Rosa.
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.
Gulf of Tehuantepec is a large body of water on the Pacific coast of the Isthmus of Tehuantepec, southeastern Mexico, at. Many Pacific hurricanes form in or near this body of water. A strong, gale-force wind called the Tehuano periodically blows out over the waters of the Gulf of Tehuantepec, inducing strong upwelling of nutrient-rich waters which support abundant sea life.
Over the next day, Rosa continued to strengthen, becoming the tenth hurricane of the season at 12:00 UTC on September 26.Around that time, the NHC indicated that Rosa had a solid mid-level ring and strong, well developed banding in the southern half of the system. Rosa's intensity leveled off for about eighteen hours before strengthening resumed, resulting in the system attaining Category 2 status on September 27 at 12:00 UTC, and major hurricane status six hours later. On September 28, at 03:00 UTC, Rosa peaked with maximum sustained winds of 150 mph (240 km/h) and a minimum central pressure of 936 mbar (27.64 inHg), becoming the seventh Category 4 hurricane of the season. Shortly after, the NHC stated that Rosa's eye had warmed considerably and the clouds in the inner ring had warmed considerably, which marked the commencement of an eyewall replacement cycle. By the afternoon of September 28, Rosa began to track northwest in response to an approaching mid- to upper-level trough. As the eyewall cycle took place and Rosa began to track towards cooler water, the storm steadily weakened and was dwongraded to Category 2 status at 00:00 UTC on September 29. After completing its eyewall replacement cycle, the storm briefly re-intensified, following a major increase in organization and the expansion of its northeastward outflow channel. However, westerly wind shear caused the circulation to become displaced, as it tracked due north under the increasing influence of the trough. Rosa resumed weakening, falling to Category 1 status at 12:00 UTC on September 30.
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.
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.
Eyewall replacement cycles, also called concentric eyewall cycles, naturally occur in intense tropical cyclones, generally with winds greater than 185 km/h (115 mph), or major hurricanes. When tropical cyclones reach this intensity, and the eyewall contracts or is already sufficiently small, some of the outer rainbands may strengthen and organize into a ring of thunderstorms—an outer eyewall—that slowly moves inward and robs the inner eyewall of its needed moisture and angular momentum. Since the strongest winds are in a cyclone's eyewall, the tropical cyclone usually weakens during this phase, as the inner wall is "choked" by the outer wall. Eventually the outer eyewall replaces the inner one completely, and the storm may re-intensify.
By September 30, a combination of strong southwesterly wind shear, dry air entanglement, and cooler sea surface temperatures caused the core of Rosa to quickly erode, resulting in the collapse of its eye and convection in the storm's southern semicircle.On the morning of October 1, at 00:00 UTC, Rosa weakened into a tropical storm. Shortly after, Rosa began travelling towards the northeast. Twenty-four hours later, Rosa weakened into a tropical depression, with the NHC reporting that the remaining convection was displaced to the northeast of the system's center and that the circulation was becoming elongated. At 11:00 UTC, Rosa made landfall approximately 70 mi (115 km) southeast of Punta San Antonio in Baja California. The NHC issued its last advisory on Rosa at 16:00 UTC as it began to cross into the Gulf of California, after which the Weather Prediction Center (WPC) began issuing storm summaries on the system. On the same day, the WPC noted that Rosa's low-level and mid-level remnants had split, with the surface low of Rosa located in the Gulf of California while its mid-level remnants were over northeast Arizona. On October 3, the remnants of Rosa were absorbed into a developing upper-level low off the coast of California, and the WPC issued their last advisory on the system.
The Gulf of California is a marginal sea of the Pacific Ocean that separates the Baja California Peninsula from the Mexican mainland. It is bordered by the states of Baja California, Baja California Sur, Sonora, and Sinaloa with a coastline of approximately 4,000 km (2,500 mi). Rivers which flow into the Gulf of California include the Colorado, Fuerte, Mayo, Sinaloa, Sonora, and the Yaqui. The gulf's surface area is about 160,000 km2 (62,000 sq mi). Depths range from fording at the estuary near Yuma, Arizona, to in excess of 3,000 meters (9,800 ft) in the deepest parts.
The Weather Prediction Center (WPC), located in College Park, Maryland, is one of nine service centers under the umbrella of the National Centers for Environmental Prediction (NCEP), a part of the National Weather Service (NWS), which in turn is part of the National Oceanic and Atmospheric Administration (NOAA) of the U.S. government. Until March 5, 2013 the Weather Prediction Center was known as the Hydrometeorological Prediction Center (HPC). The Weather Prediction Center serves as a center for quantitative precipitation forecasting, medium range forecasting, and the interpretation of numerical weather prediction computer models.
Arizona is a state in the southwestern region of the United States. It is also part of the Western and the Mountain states. It is the sixth largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona shares the Four Corners region with Utah, Colorado, and New Mexico; its other neighboring states are Nevada and California to the west and the Mexican states of Sonora and Baja California to the south and southwest.
On September 29, the Government of Mexico issued a tropical storm watch for the Pacific Coast of the Baja California peninsula from Punta Abreojos to Cabo San Quintin.On the next day, the Government of Mexico changed the tropical storm watches on the west coast of Baja California to tropical storm warnings and issued watches for the east coast of Baja California from Bahia de los Angeles to San Felipe. All the watches and warnings were discontinued after Rosa weakened to a tropical depression.
Punta Abreojos is a fishing town in Mulegé Municipality, Baja California Sur, Mexico.
San Felipe is a town on the bay of San Felipe in the Gulf of California in the Mexican state of Baja California, 190 km south of the United States border and within the municipality of Mexicali. The population of San Felipe was 17,708 at the 2015 census, and can increase by up to 5,000 due to the presence of Canadian and U.S. part-time residents, who travel to the town from the United States during the American holidays Spring Break and Memorial Day. It also serves as a borough seat of its surrounding area.
On October 2, a woman drowned in Caborca after being swept away by flood waters.The governor of Baja California, Francisco Vega de la Madrid, issued a State of Emergency for the cities of Ensenada and Mexicali. Schools were closed on October 1 in several communities as Rosa approached the area. Classes were also suspended in the neighboring state of Sonora, as floodwaters inundated roads and highways across the state. Damage from the port of San Felipe totaled about MX$10 million (US$531,000). On October 3, an emergency declaration was approved for Puerto Peñasco after Rosa passed by. Dozens of homes and businesses experienced flooding after a total of 3.94 in (100 mm) of rain fell. Multiple road closures occurred as a result of the flooding.
After Rosa made landfall, its remnants tracked northward, spawning rain showers and thunderstorms in the Four Corners region.On September 30, in anticipation of severe rainfall from the remnants of Rosa, flood watches and warnings were issued for Southern California, Arizona, southwest Colorado, Utah, central Nevada, and a small portion of southeast Idaho. At that time, rainfall was causing flooding in Arizona and Southern California. In San Bernardino County, the remnants of Rosa and a Pacific low produced thunderstorms over the Mojave Desert. On October 1, portions of U.S. Route 95 were flooded out, with floodwaters depositing rocks and other objects on the road. Additionally, portions of State Route 62 and State Route 127 were also flooded out.
By 09:00 UTC on October 3, a preliminary total of 6.89 in (175 mm) was reported at Towers Mountain, Arizona, with other areas reporting 1 to 5.5 in (25 to 140 mm) of rain. After more than 2 in (51 mm) of rain fell, the National Weather Service issued a flash flood warning for the Phoenix area and firefighters were forced to rescue several people from flooded vehicles. Additionally, over two dozen road closures and 80 car crashes occurred. Multiple schools and businesses were closed due to flooding At the intersection of 35th Avenue and Cactus Road, it was reported that a sinkhole had formed. Rosa also caused flash flooding in the communities of Guadalupe, Glendale, Scottsdale, Fountain Hills, Deer Valley, and Sun City. Rosa caused thousands of power outages in Yuma. On October 3, a 26-year-old French woman was killed just north of Cameron after being struck by a vehicle. Portions of U.S. Route 89 were washed out after flash flooding affected the area. In Pioche, Nevada, flash flooding left several buildings inundated and water and debris on Main Street.
At Menager Lake near Sells, rainfall from Rosa filled the Menagers Dam above maximum capacity, raising concerns about its structural integrity.This prompted the National Weather Service in Tucson to recommend immediate evacuation for the village of Ali Chuk on October 2, stating that dam failure was imminent. On October 2, 162 people were evacuated from Ali Chuk, 32 from Kohatk, and 23 others from the Menegar's Dam community. Despite the water level having receded, there were still concerns that the dam could fail. On October 4, the Tohono O’odham Nation announced that they were assembling an engineering team to inspect the dam before more rain arrives. On the same day, a 34-year-old man was found deceased after the flooding in Golden Valley. Damage from flooding totaled about US$50 million.
Hurricane Juliette was a long-lasting Category 4 hurricane in the 2001 Pacific hurricane season. It caused 12 deaths and $400 million in damage when it hit Baja California in late September.
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.
Hurricane Howard was a powerful Category 4 hurricane which produced large swells along the coasts of the Baja California Peninsula and southern California. The eighth named storm of the 2004 Pacific hurricane season, Howard originated out of a tropical wave off the coast of Mexico on August 30. Traveling towards the northwest, the storm gradually strengthened, becoming a hurricane on September 1 and reaching its peak intensity the following day with winds of 140 mph (220 km/h). Decreasing sea surface temperatures then caused the storm to weaken. By September 4, Howard was downgraded to a tropical storm. The next day, it degenerated into a non-convective remnant low pressure area which persisted for another five days before dissipating over open waters.
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 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.
Hurricane Dora was the strongest tropical cyclone in the northeastern Pacific in 2011. Dora developed from a tropical wave south of Honduras on July 18. Moving northwestward in favorable conditions, the system quickly intensified to tropical storm status and attained hurricane intensity the next day. Rapid intensification ensued shortly thereafter, bringing the storm to its peak intensity on July 21 as a Category 4 hurricane, with a minimum barometric pressure of 929 mbar and maximum sustained winds of 155 mph (250 km/h). However, the storm's path into an area with cool sea surface temperatures and wind shear caused Dora to quickly deteriorate and weaken. By July 24, Dora had degenerated into a remnant low-pressure area west of the Baja California Peninsula. Dora brought stormy conditions to the southwestern Mexico coast and the Baja California Peninsula throughout its existence. Remaining off the coast from its formation to dissipation, Dora's effects on land were slight. However, the outer rainbands of the hurricane caused flooding and mudslides in southern Mexico and Guatemala, while rough surf toppled a lighthouse and damaged 60 restaurants along the coast. The hurricane's remnants contributed to heightened shower and thunderstorm activity across New Mexico and Arizona in late July.
Hurricane Lidia was the strongest tropical cyclone of the 1993 Pacific hurricane season. Forming from a tropical wave on September 8, Lidia steadily organized and became a hurricane on September 10. The hurricane continued to strengthen while developing a well-defined eye, and peaked as a Category 4 hurricane on September 11. However, it weakened considerably before making landfall in Sinaloa as a Category 2 storm. Lidia dissipated near Austin on September 14 and was later absorbed by a cold front. Across Mexico, the hurricane killed seven people; over 100,000 people were forced to evacuate their homes. A total of 160 homes were destroyed and 10,000 people were left homeless because of the storm. In the United States, five people suffered injuries and storm damage totaled $8 million.
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 Odile is tied for the most intense landfalling tropical cyclone on the Baja California Peninsula during the satellite era. Sweeping across the peninsula in September 2014, Odile inflicted widespread damage, particularly in the state of Baja California Sur, in addition to causing lesser impacts on the Mexican mainland and Southwestern United States. The precursor to Odile developed into a tropical depression south of Mexico on September 10 and quickly reached tropical storm strength. After meandering for several days, Odile began to track northwestward, intensifying to hurricane status before rapidly reaching its Category 4 hurricane peak intensity on September 14. The cyclone slightly weakened before making landfall near Cabo San Lucas with winds of 125 mph (205 km/h). Odile gradually weakened as it tracked across the length of the Baja California Peninsula, briefly crossing into the Gulf of California before degenerating into a remnant system on September 17. These remnants tracked northeastward across the Southwestern United States before they were no longer identifiable on September 19.
Hurricane Bud was a powerful tropical cyclone that produced heavy rainfall and flash flooding across Northwestern Mexico and the Southwestern United States. The second named storm and major hurricane of the 2018 Pacific hurricane season, Bud originated from a tropical wave that departed from Africa on May 29. It then travelled across the Atlantic Ocean before crossing over South America and entering the Northeast Pacific Ocean late on June 6. The system then moved northwest and steadily organized, becoming a tropical depression late on June 9 and Tropical Storm Bud early the next day. Favorable upper-level winds and ample moisture allowed the storm to rapidly intensify to a hurricane late on June 10 and further to a major hurricane on June 11. Bud ultimately peaked the next morning with maximum sustained winds of 140 mph (220 km/h) and a minimum barometric pressure of 943 mbar. It curved north while rapidly succumbing to the effects of ocean upwelling, making landfall on Baja California Sur as a minimal tropical storm early on June 15. On the next day, land interaction and increasing wind shear caused Bud to degenerate to a remnant low, and Bud dissipated completely on June 16.
Tropical Storm Carlotta was a tropical cyclone that caused flooding within several states in southwestern and central 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. Following an increase in organization, the system was designated as a tropical depression on June 14 and was upgraded to tropical storm status the following evening. On June 16, Carlotta 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.
Tropical Depression Nineteen-E was a weak tropical cyclone that caused flooding throughout Northwestern Mexico and several states within the United States. Nineteen-E originated from a tropical wave that left the west coast of Africa on August 29 to 30. It continued westward, crossed over Central America, and entered the northeastern Pacific Ocean by September 7. It then meandered to the southwest of Mexico for the next several days as it interacted with a mid-to-upper level trough. The National Hurricane Center (NHC) continued to track the disturbance for the next several days as it traveled northward. A surface trough developed over the Baja California peninsula on September 18. Despite disorganization and having close proximity to land, the disturbance developed into a tropical depression in the Gulf of California on September 19, after having developed a circulation center and more concentrated convection. The system peaked with maximum sustained winds of 35 mph (55 km/h) and a minimum central pressure of 1002 mbar.
Hurricane Sergio was a powerful and long-lived tropical cyclone that affected the Baja California Peninsula as a tropical storm. Sergio became the eighth Category 4 hurricane in the East Pacific for 2018, breaking the old record of seven which was set in 2015. The twentieth named storm, eleventh hurricane, and ninth major hurricane of the season, Sergio originated from a broad area of low pressure that formed a few hundred miles south-southeast of the southern coast of Mexico on September 26. The National Hurricane Center monitored the disturbance for a few days until it organized into a tropical storm, after which it was assigned the name Sergio. The system gradually strengthened for the next couple of days, becoming a hurricane on October 2. Sergio then began a period of rapid intensification, becoming a major hurricane later that day. Intensification then halted for about twelve hours before resuming on October 3. The next day, Sergio peaked as a Category 4 hurricane with maximum sustained winds of 140 mph and a minimum central pressure of 942 mbar. Sergio maintained peak intensity for six hours before beginning to weaken. On October 5, the system bottomed out as a low-end Category 3 hurricane. Sergio then began another period of intensification, achieving a secondary peak on October 6. The next day, Sergio began to weaken again, falling below major hurricane strength. At the same time, Sergio unexpectedly assumed the structure of an annular tropical cyclone. By October 9, Sergio had weakened into a tropical storm. On October 12, Sergio made landfall as a tropical storm on the Baja California Peninsula, and later in northwestern Mexico as a tropical depression before dissipating early on October 13.
Tropical Storm Vicente was a weak and small tropical cyclone affected the southwestern Mexico in late October 2018, causing deadly flooding and 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.
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. 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.
person reportedly drowned in Mexico after being swept away by floodwaters.
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