1981 Pacific hurricane season

The 1981 Pacific hurricane season was a slightly below average Pacific hurricane season. The season officially started on May 15 in the eastern Pacific basin and June 1 in the central Pacific basin. Both basins' seasons ended on November 30; these dates conventionally delimit the period during which most tropical cyclones form in the northeastern Pacific Ocean. The first tropical cyclone of the season was designated on May 30, and the final storm of the season, Hurricane Otis, dissipated on October 30. The season produced fifteen named storms and a total of eight hurricanes, which was near normal. However, the total of one major hurricane was below the average of three.

The strongest tropical cyclone of the season was Hurricane Norma, which was a powerful Category 3 hurricane on the Saffir–Simpson Hurricane Scale. The storm caused six deaths – five in Texas, and one in Mexico, due to severe flooding. Additionally, the storm caused $74 million (equivalent to $ million in ) in damage, which is credited to significant crop damage and many tornadoes. However, the deadliest tropical cyclone of the season was Tropical Storm Lidia, which made two landfalls – one on the southern tip of the Baja California Peninsula and the other along the shores of Sinaloa in early October. As the result of its heavy rainfall in northwestern Mexico, seventy-three fatalities were reported, along with $80 million in damage.

Seasonal summary

There was an absence in storm activity across the Central Pacific Hurricane Center's area of responsibility, as no storms developed in the basin. However, two tropical cyclones from the eastern Pacific, Greg and Jova, entered the central Pacific, the latter entering as a hurricane.

Six tropical cyclones made landfall in Mexico. First, Tropical Storm Adrian made landfall east-southeast of Acapulco, but did not cause any damage. Afterwards, Tropical Storm Irwin made landfall in Baja California Sur, but similarly to Adrian, did not cause any damage. Tropical Storm Knut later made landfall near Mazatlán with winds equivalent to a minimal tropical storm, but no deaths or damage was reported. Tropical Storm Lidia struck about south of Los Mochis on October 8, with winds of 45 mph (75 km/h). Heavy rainfall associated with the cyclone caused moderate damage in northwestern Mexico, and at least seventy-three deaths can be attributed to the storm. On May 30, an area of intense shower and thunderstorm activity located 270 mi (430 km) south of the Mexican coastline. The second to strike the area in 10 days, Norma was absorbed by a frontal system on October 14. The combined entity produced heavy rainfall and severe weather across Texas, which subsequently led to severe crop damage. The final storm to make landfall on Mexico during the 1981 season was Hurricane Otis. Intensifying into a hurricane by October 26, the hurricane brushed the coast of Jalisco before making landfall near Mazatlán at hurricane intensity on October 30. Otis was the second of two hurricanes to make landfall in the country this season.

Systems

Tropical Storm Adrian

On May 30, an area of intense shower and thunderstorm activity located to the south of the Mexican coastline intensified into a tropical depression. Drifting towards the north and then east-northeast around an area of high pressure centered off the southern coast of Mexico, the depression began to strengthen over water. Twelve hours after formation, the depression strengthened into Tropical Storm Adrian. Reaching a peak intensity of 45 mph (75 km/h), Adrian began to move over slightly cooler ocean temperatures of and subsequently began to weaken. After being downgraded to a tropical depression by June 2, data from two cargo ships, the Androemda and Santa Maria, were helpful in locating Adrian's center of circulation as it moved towards the Mexican coastline. On June 4, the system made landfall east-southeast of Acapulco; however, no damage associated with the tropical cyclone was reported, and Adrian dissipated later that same day.

Tropical Storm Calvin

An area of disturbed weather located several hundred miles to the south of Acapulco organized into a tropical depression on July 4. Moving towards the west-northwest over warm sea-surface temperatures, the depression intensified into a tropical storm on July 5, receiving the name Calvin. Reaching a peak intensity of 50 mph (85 km/h) later that day, Calvin began to move north-northwest around the western periphery of a high pressure system located over extreme northern Mexico. Calvin then moved over cooler water and subsequently weakened to a minimal tropical storm. Located 98 mi (158 km) south-southeast of Cabo San Lucas on July 8, Calvin further weakened to a tropical depression and turned to the west. The system dissipated the following day.

Hurricane Dora

Based on satellite imagery and data from a nearby ship, Yamazuru, a tropical depression formed far away from land on July 10. Passing north of Clipperton Island, the depression began to strengthen under favorable atmospheric conditions, and was designated Tropical Storm Dora twelve hours after formation. Moving towards the west-northwest, Dora attained hurricane status on July 13; subsequently, the ship Amestelmolen reported seas of , a minimum barometric pressure of , and winds as it passed north of the storm's center. As Dora reached its peak intensity of 90 mph (150 km/h) on July 14, a well-defined eye became apparent on satellite imagery, and the storm turned more towards the west. Cooler ocean temperatures below 74 °F (23 °C) subsequently caused the hurricane to weaken, and it was downgraded to a tropical storm on July 15. The storm's structure further deteriorated the following day, and Dora dissipated over southwest of Cabo San Lucas.

Hurricane Hilary

Based on a report from a cargo ship, the Eastern Pacific Hurricane Center upgraded a tropical disturbance into a tropical depression roughly west of the Mexican coast at 2105 UTC on August 21. Four hours later, the system strengthened into Tropical Storm Hilary. After turning towards the west, it passed about south of Socorro Island. Even though Hilary developed a well-defined eye late on August 23, the cyclone was not upgraded into a hurricane until the next afternoon. Accelerating, Hilary reached its peak strength of 85 mph (140 km/h) while located west of Cabo San Lucas. Moving west, Hilary began to weaken over water. Late on August 28, nearly 24 hours following Hilary's downgrade into a tropical depression, the tropical cyclone dissipated far from land. the depression intensified into Tropical Storm Lidia on October 7. Lidia moved generally north, and reached its peak wind speed of 50 mph (85 km/h). Despite encountering warm ocean temperatures, Lidia slowly weakened as it moved towards southern Baja California Peninsula. The tropical cyclone passed over the southern tip of the Baja California Peninsula on 1700 UTC October 7; at the time of the landfall Lidia was located about northwest of Cabo San Lucas. Two hours later,

Heavy rain caused flooding that cut off seven towns in Sinaloa from the outside world. It also contaminated the water supply in Culiacán, leaving many without clean drinking water. In one village, six soldiers died. Around Los Mochis, four people were killed, In Culiacán, eleven people were killed. Losses to cattle, crops, and fishing vessels were more than $80 million (equivalent to $ million in ).

Tropical Storm Max

On October 7, a tropical depression developed several hundred miles to the south of the Mexican coastline. Under favorable environmental conditions, the depression began to organize, and became a tropical storm twelve hours after formation, receiving the name Max. Moving north-northwestward, Max reached a peak intensity of briefly on October 9 before the system began to move into an area with cooler ocean temperatures and stronger wind shear. Early on October 10, Max weakened to a tropical depression, and dissipated during the afternoon hours of the same day without any effects to land. while weakening. Five thousand two hundred residents need to be evacuated from low-lying areas. The remnants of the storm moved into Texas and Oklahoma. The heavy rainfall caused two rivers to reach flood-stage. A total of five people were killed in the United states, During October 13 and 14, a total of 13 tornadoes were reported in northern Texas and southern Oklahoma, including a F2 tornado in McLennan that injured four people and caused $25 million in damage. In Oklahoma, 60 bridges were washed away due to flooding.

Hurricane Otis

On October 24, the season's last tropical cyclone developed to the south of the Mexican coastline. Moving towards the west-northwest, the depression quickly strengthened into a tropical storm, receiving the name Otis. Turning towards the north and eventually northeast, Otis steadily strengthened, and intensified into a Category 1 hurricane early on October 26. Sharply bending back towards the west-northwest, and eventually the north, Otis reached a peak intensity of before higher wind shear and cooler sea surface temperatures began to impede on the system's organization. On October 29, Otis skirted the coast of Jalisco as a minimal Category 1 hurricane before weakening to a tropical storm. The next day, Otis made landfall near Mazatlán before being absorbed by a frontal system. but the system is not recognized by either NHC or CPHC.

On August 4, a tropical depression developed southwest of Cabo San Lucas. Despite being over warm sea surface temperatures, the depression dissipated the following day as wind shear began to significantly increase. Thus, the depression was never named, and never had any effects on land. Two weeks later, a tropical disturbance developed south-southeast of Socorro Island drifted north-northwest of a couple of days before organizing into a tropical depression a short distance southwest of Cabo San Lucas. Despite being located over warm sea surface temperatures, it failed to intensify. Tropical Depression Nine-E moved westward for 12 hours prior to dissipation. Most of these names were used for the first time, except for Fernanda, Hilary, and Norma, which were previously used in the old four-year lists. No names were retired from this list following the season, and it was next used (expanded to include "X", "Y", and "Z" names) for the 1987 season.

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Adrian
Beatriz
Calvin
Dora
Eugene
Fernanda
Greg*

Hilary
Irwin
Jova*
Knut
Lidia
Max
Norma

Otis

Had any tropical storms formed in the North Pacific from 140°W to the International Date Line, their names would have come from a series of four rotating lists. Names are used one after the other without regard to year, thus when the bottom of one list is reached, the next named storm receives the name at the top of the next list.