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 in the Eastern Pacific Ocean (east of from 140°W), and on June 1 in the Central Pacific (from 140°W to the International Date Line) in the Northern Hemisphere. The season ended in both regions 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. 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.
In June, Tropical Storm Dolores made landfall near the border of the Mexican states of Colima and Michoacán, killing three people and resulting in US$50 million in insured losses. Just a week later, Hurricane Enrique paralleled the west coast of Mexico, causing an additional two fatalities and a similar amount of damage. In August, Hurricane Nora made landfall on the state of Jalisco and paralleled the Pacific coast of Mexico until dissipating, resulting in an estimated $100 million in damage and three more deaths. Less than two weeks later, Hurricane Olaf made landfall on Baja California Sur as a Category 2 hurricane. In October, Hurricane Pamela struck Nayarit at Category 1 intensity, leaving four people missing and severe flooding. Later that month, Hurricane Rick struck near the Michoacán-Guerrero border at peak intensity as a strong Category 2 hurricane. Altogether, five systems made landfall in Mexico in 2021, the greatest number since 2018.
Seasonal forecasts
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 1991 and 2020 contained approximately 15 tropical storms, 8 hurricanes, and 4 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. Factors they expected to reduce activity were near- or below-average sea surface temperatures across the eastern Pacific and the El Niño–Southern Oscillation remaining in the neutral phase, with the possibility of a La Niña developing.
On May 12, 2021, the Servicio Meteorológico Nacional issued its forecast for the season, predicting a total of 14–20 named storms, 7–10 hurricanes, and 4–5 major hurricanes to develop. On May 20, 2021, the National Oceanic and Atmospheric Administration (NOAA) issued their outlook, calling for a below-normal to near-normal season with 12–18 named storms, 5–10 hurricanes, 2–5 major hurricanes, and an accumulated cyclone energy index of 65% to 120% of the median.
Seasonal summary
The 2021 Pacific hurricane season began on May 15 in the East Pacific and on June 1 in the Central Pacific. Overall activity included 19 named storms, 8 hurricanes, and 2 major hurricanes. The total of named storms was above the 1991–2020 average, while the number of hurricanes was average, and the sum of major hurricanes was below average. The official start date was preceded by the formation of Tropical Storm Andres, the earliest named storm on record in the East Pacific. It was accompanied by Tropical Storm Blanca later in May. The following month included the formations of tropical storms Carlos and Dolores, in addition to Hurricane Enrique. While Carlos remained away from land, Dolores made landfall on the Mexico coastline and Enrique delivered impacts across southwestern sections of the country while it passed just offshore. Above-average seasonal activity continued into July with the development of hurricanes Felicia and Hilda, Tropical Storm Guillermo, and Tropical Depression Nine-E; none of these cyclones impacted land. In August, Hurricane Nora made landfall along the west-central coastline of Mexico. Its formation was preceded by Hurricane Linda and tropical storms Ignacio, Kevin, and Marty, which did not impact land. September marked a stark turn around to the activity of the previous months, as it only featured Olaf, which struck San José del Cabo as a Category 2 hurricane. Two hurricanes – Pamela and Rick – moved ashore the Mexico coastline in October. An additional two storms, Terry and Sandra, developed in November, the fourth consecutive November with at least one named storm. Furthermore, those cyclones existed simultaneously, the first occurrence in the East Pacific during November on record. The Accumulated Cyclone Energy index for the 2021 Pacific hurricane season as calculated by Colorado State University using data from the National Hurricane Center was approximately 94 units, about 30 percent below average.
Systems
Tropical Storm Andres
In early May, the passage of a convectively-coupled Kelvin wave (CCKW) enhanced the eastern Pacific monsoon trough, leading to an area of disturbed weather. This disturbance interacted with a Gulf of Tehuantepec gap wind event, which led to the formation of an ill-defined low-pressure area. Despite a marginal environment of wind shear and dry air, the system slowly organized and developed into a tropical depression around 06:00 UTC on May 9. Six hours later, it intensified into Tropical Storm Andres, becoming the earliest tropical storm on record in the East Pacific basin. Andres maintained peak winds of 40 mph (64 km/h) as it curved north-northwest, and the compounded effects of colder waters and drier air atop moderate wind shear instead caused the system to begin weakening. All associated convective activity dissipated by 06:00 UTC on May 11, when Andres was downgraded to a remnant area of low pressure. The low curved west on May 12 and dissipated later that day.
There are no reports of damage or casualties directly associated with Tropical Storm Andres; however, some other rainstorms associated with Andres produced heavy rainfall in Southwestern Mexico. Moisture from the storm caused intense rain and even a hailstorm as far east as the State of Mexico, including in the state's capital, Toluca. Vehicles became stranded in floods, some small trees got knocked over, and about 50 houses were damaged by a flooding river. Four municipalities in the Toluca Valley were flooded; 30 cars were stranded in a flooded parking lot of a church in Metepec, and in Lerma, a shopping center's roof was damaged due to flying debris and hail.
Tropical Storm Blanca
Blanca originated from a tropical wave that crossed Central America on May 27. Shower and thunderstorm activity increased ahead of the wave axis, followed by the formation of a low-pressure area. After further organization, the developed into a tropical depression around 18:00 UTC on May 30. It intensified into Tropical Storm Blanca around 12:00 UTC the next day. Favorable environmental conditions allowed the cyclone to intensify, and it attained peak winds of 60 mph (97 km/h) on June 1 when prominent rainbands wrapped into the center. Thereafter, an upper-level trough off the southwestern United States increased shear over Blanca and injected dry air into the core, resulting in a weakening trend. The storm's low-level circulation became separated from convection, and it degenerated to a remnant low by 00:00 UTC on June 4. The remnants of Blanca, which were previously tracking west-northwest, curved toward the west before dissipating later the next day.
Tropical Storm Carlos
A trough developed within the Intertropical Convergence Zone (ITCZ) on June 1. It moved west across the eastern Pacific for several days but failed to develop into a tropical cyclone on several occasions, either because it lacked a coherent circulation or because it lacked sustained convection. A burst of thunderstorms resulted in the formation of a well-defined center on June 12, and the system steadily organized over ensuing hours, finally resulting in the formation of a tropical depression by 12:00 UTC that day. Six hours later, the depression intensified into Tropical Storm Carlos to the southwest of Baja California Sur. The surrounding environment was initially favorable for development and allowed the system to reach peak winds of 50 mph (80 km/h) as it curves west-southwest. However, increasing dry air around the storm caused Carlos to gradually lose its convection, which ultimately resulted in its degradation to a remnant low by 12:00 UTC on June 16. The remnant system was reabsorbed into the ITCZ the following day.
Tropical Storm Dolores
A broad cyclonic gyre over Central America, spawned from the interaction of the monsoon trough and a tropical wave, led to the formation of an area of low pressure south of Mexico on June 16. The low gradually organized and became a tropical depression around 18:00 UTC on June 17 while located about 195 mi (315 km) south-southwest of Acapulco. The depression became Tropical Storm Dolores within six hours. Ridging over Mexico shifted east as Dolores developed, causing the cyclone to curve to the north-northwest. A favorable environment facilitated its development, and the storm reached peak winds of 70 mph (110 km/h) as it made landfall near San Juan de Alima, Michoacán, around 15:00 UTC on June 19. It harbored a well-defined eyewall at the time, and it is possible that Dolores temporarily surpassed tropical storm intensity. Once inland, though, the system quickly weakened over the high terrain of southwestern Mexico, dissipating around 06:00 UTC on June 20.
Dolores produced a wide expanse of 5 in (130 mm) or greater rainfall across southwestern Mexico, including a peak accumulation of 17.31 in (440 mm) in Callejones, Colima. At least 20 municipalities in Michoacán were affected by flooding or uprooted trees, blocking many routes through these communities. In Jalisco, the Marabasco River overflowed its banks, briefly isolating 80 homes. Throughout Guerrero, Michoacán, Colima, and Jalisco, more than 50,000 customers lost power. Overall damage to more than 1,000 structures totaled in excess of $50 million. Three people were killed by lightning, two in Oaxaca and one in Jalisco.
Hurricane Enrique
A tropical wave left Africa on June 14 and crossed Central America a week later. The system coalesced as it moved south of Mexico, becoming Tropical Storm Enrique by 12:00 UTC on June 25 since the incipient system was already producing gale-force winds at the time of development. Moderate wind shear initially inhibited the cyclone, but these unfavorable winds slackened late on June 25, allowing the cyclone to begin a 24-hour period of rapid intensification. Enrique intensified into a hurricane around 12:00 UTC on June 26 and reached peak winds of 90 mph (140 km/h) the next morning as it was characterized by a cloud-filled eye. The storm curved north and then bent back northwest, passing within 45 miles (72 km) of the Mexico coastline. Dry air off the mountainous terrain of that country, and later colder waters, soon caused Enrique to lose organization. By 18:00 UTC on June 30, the increasingly disheveled circulation was absorbed into a broad trough east of Baja California.
Two people died from rip currents in Pie de la Cuesta, Guerrero. At least 207 homes were damaged by landslides and winds caused by Enrique in Guerrero. In Lázaro Cárdenas, Michoacán, areas were inundated by more than 50 cm (20 in) of floodwater. A total of 115,904 customers lost power across Jalisco, although 96% of homes returned with power a couple of hours later. A citywide power outage also occurred in Tepic.
Hurricane Felicia
A disturbance of unclear origin was identified over Central America and the far eastern Pacific on July 9. The system progressed westward over the open ocean during the following days, developing into a tropical depression around 00:00 UTC on July 14 and becoming Tropical Storm Felicia six hours later. Felicia immediately underwent rapid intensification, becoming a hurricane by 06:00 UTC on July 15 and a major hurricane 24 hours later. Early on July 17, the system attained peak winds of 145 mph (233 km/h). At that time, Felicia displayed a warm eye encapsulated by a ring of −70 °C (−94 °F) convection and little additional rainbands outside the eyewall, a signature sign of an annular tropical cyclone. It was also a very small storm, with hurricane-force winds extending only 15 miles (24 km) from the center. After a brief westward turn, Felicia resumed a west-northwestward motion into much more hostile environmental conditions on July 18. The cyclone rapidly weakened and degenerated to a remnant low by 18:00 UTC on July 20 while located well east of Hawaii. Low-level wind flow steered the remnant low of Felicia to the west-southwest, and it opened into a trough two days later.