2001 Pacific hurricane season

The 2001 Pacific hurricane season was a relatively near-average Pacific hurricane season which produced fifteen named storms, though most were rather weak and short-lived. Only eight hurricanes formed and two major hurricanes. The season officially began on May 15 in the East Pacific Ocean, and on June 1 in the Central Pacific; they ended on November 30. These dates conventionally delimit the period of each year when most tropical cyclones form in the Pacific basin. However, the formation of tropical cyclones is possible at any time of the year.

The first storm of the season, Hurricane Adolph, formed on May 25 which became the strongest hurricane in the month of May at the time. Tropical Storm Barbara passed just north of Hawaii, bringing minimal impact. The most notable storm that year was Hurricane Juliette, which caused devastating floods in Baja California Peninsula. September was much more active with six systems developing, of which three became hurricanes. Activity decreased appreciably in October and November as most of the storms remained weak and short-lived. The final storm of the season, Hurricane Octave, dissipated on November 3, about twenty-seven days before the official end of the season. Overall, this season was drastically less active and destructive, causing about $401 million in damages and thirteen fatalities.

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Seasonal summary

thumb|270px|Hurricane Gil (left) and Tropical Storm Henriette (right) on September 7

The season officially began on May 15 in Eastern Pacific and on June 1 in Central Pacific; both ended on November 30. There were fifteen tropical storms in the eastern Pacific basin during the 2001 season. Of those, seven became hurricanes, of which two became major hurricanes by reaching Category 3 intensity or higher on the Saffir–Simpson hurricane wind scale (SSHS). Four tropical depressions formed and dissipated before reaching the intensity of a named storm. In the eastern Pacific proper, the season saw average activity in terms of the number of named systems, but the season also featured seven hurricanes and two major hurricanes, both totals a bit below long term averages. The first storm of the season, Hurricane Adolph, formed in late May, slightly ahead of schedule, and at the time was the strongest May hurricane on record. This season featured only one named storm in the month of June, followed by three in July and only one during August, including none during the first three weeks of August, a time that usually sees several storms. Activity picked up during the second half of the season, starting in September, when five named storms were observed, before decreasing to three and no storms in October and November respectively. The newly formed depression moved slowly eastward due to weak steering currents aloft. Located in conditions ideal for tropical development, the developing cyclone formed a central dense overcast, a large area of deep convection. The depression steadily intensified to become Tropical Storm Adolph on May 26 about south-southwest of Acapulco. Adolph was in a low wind shear environment with warm sea surface temperatures. thus causing the tropical storm to approach Mexico. A banding eye feature, a type of eye common in minor hurricanes, became apparent on satellite imagery. Convection around the eye deepened while the eye became more pronounced, and Adolph was upgraded to hurricane strength on May 27. allowed the hurricane to begin a burst of rapid intensification, dropping 1.46 mbars per hour. While reducing in size, The trend of weakening continued as the eye definition and convection oscillated in presentation. As the storm passed over increasingly colder waters and into an area of stable air, the system weakened more quickly, and dissipated on June 1, while located about south-southwest of Baja California. resulted in the issuance of a tropical storm warning and a hurricane watch for southern Mexico around the time when the cyclone attained major hurricane strength. The threat for heavy rainfall was mentioned for areas from Puerto Ángel to Zihuatanejo when Adolph was a depression and later from Acapulco to Lázaro Cárdenas. The government of Mexico expressed concern that rain and waves from Adolph would affect Oaxaca, Colima, Jalisco, Michoacán, and Guerrero. The hurricane was responsible for the closure of ports in Acapulco to small vessels. Adolph ultimately produced rainfall and heavy surf to the southwest Mexican coastline. Although the depression remained poorly organized, it was upgraded to Tropical Storm Barbara. At 12:00 UTC on June 21, the storm attained its peak intensity with maximum sustained winds of and a minimum barometric pressure of . Shortly thereafter, Barbara began encountering unfavorable conditions, such higher wind shear and cooler sea surface temperatures.

It weakened to a tropical depression at 18:00 UTC on June 26, while crossing 140°W into the Central Pacific Hurricane Center's area of responsibility. The depression passed north of the Hawaiian Islands on June 25, then weakened to an easterly wave to the northwest of Kauai on June 26. The remnants of Barbara continued west-northwest until being absorbed by a frontal zone near the International Date Line on June 30. Barbara was the first tropical cyclone in the Central Pacific during the month of June, the second being Tropical Storm Boris in 2020.

Tropical Storm Cosme

A tropical wave crossed Central America and emerged into the eastern Pacific basin on July 6. The wave moved slowly westward from July 6 – July 10. On July 10, the convective pattern began to show signs of organization about south of Acapulco, Mexico, and the system received its first Dvorak satellite classification. Over the next two days, the system moved generally west-northwestward as multiple competing low-level circulations developed within the broad area of low pressure associated with it. During this period, development of the disturbance was hindered by southerly shear from an upper-level trough to the west of the disturbance that caused the system to become elongated north–south. On July 12, the upper trough cut off southwest of the disturbance and the organization improved. By early on July 13, a single low-level circulation center had become established and Tropical Depression Three-E formed about southwest of Manzanillo, Mexico.

Tropical Storm Erick

A poorly defined tropical wave traveled westward across the tropical Atlantic and reached the eastern North Pacific on July 16. The thunderstorm activity associated with the wave increased on July 18 when the disturbance was centered about south of the southern tip of the Baja California Peninsula. Thereafter, deep convection gradually developed around a large cyclonic gyre which accompanied the wave.

Hurricane Dalila

Dalila's origin is a tropical wave that moved westward from Africa and over the eastern tropical Atlantic Ocean on July 10. It crossed northern South America and Central America on the July 15 through July 17 accompanied by vigorous thunderstorm activity, and then entered the Pacific basin on July 18 as an organized area of disturbed weather. Early on July 21, the system acquired a low-level circulation and became Tropical Depression Five-E, about south of the Gulf of Tehuantepec. Moving west-northwestward, it became Tropical Storm Dalila with winds 12 hours later.

Tropical Depression Six-E

A westward moving tropical wave entered the Pacific from August 12 to 13 after crossing from the Atlantic and Caribbean. At 12:00 UTC on August 22, Tropical Depression Six-E developed from this wave. In addition to lowering sea surface temperatures, the system began to be affected by southerly wind shear, which displaced the mid-level circulation and deep convection from the low-level circulation. The National Hurricane Center later noted the disorganized state of the tropical depression as being only "... a swirl of low clouds with a few showers to the north and northeast of the center". It became elongated, and dissipated at 06:00 UTC on August 24. and after banding features increased, the system was upgraded to Tropical Storm Flossie later on August 26. While steering currents weakened, By early on August 29, further intensification was not expected, but Flossie suddenly deepened to a Category 2 hurricane. After peaking with winds of and a minimum barometric pressure of , Flossie weakened quickly, and weakened to a minimal hurricane 24 hours after peak intensity; Early on August 30, Flossie weakened to a tropical storm. On September 1, Flossie was downgraded to a tropical depression, and after becoming devoid of deep convection, the system degenerated into a remnant low on September 2. The remnants of Flossie moved inland over Baja California, eventually entering the southwestern region of the United States and dissipating.

Flossie's remnants caused flash flooding in San Diego and Riverside counties in California, dropping of rain in one hour. A strong downdraft knocked a tree onto a house. In addition, four people were struck by lightning, two of them fatally. The total cost of damage caused by Flossie's remnants was $35,000 (2001 USD).

Hurricane Gil

A tropical wave emerged into the Atlantic Ocean off the coast of Africa between August 14 and August 15. The northern part of the wave developed into Tropical Storm Dean on August 22, while the remaining portion entered the Pacific on August 24. The wave organized slowly and did not develop into a tropical depression until September 4. Situated roughly southwest of Cabo San Lucas, Mexico, the system quickly intensified and became a tropical storm six hours later, and was named Gil. By early on September 5, banding features became well-defined; the NHC simultaneously noted the possibility for interaction between Tropical Storm Gil and Tropical Depression Nine-E (later Tropical Storm Henriette), which was to the east-northeast. Although outflow from Henriette was predicted to slow or prevent intensification, Gil managed to become a hurricane early on September 6. Late on September 6, Gil intensified into a Category 2 hurricane, peaking with maximum sustained winds of and a minimum barometric pressure of . After weakening to a Category 1, Gil accelerated northward around the circulation of Henriette. Gil continued to weaken and was downgraded to a tropical depression early on September 9. Tropical Depression Gil eventually absorbed the remnants of Henriette, but dissipated by 00:00 UTC on September 10 while about east of the Hawaiian islands.

Tropical Storm Ivo

Ivo formed from a large tropical wave that moved off the African coast on August 26. The wave was accompanied by a large cyclonic rotation at the low to middle levels and numerous thunderstorms when it entered the eastern Atlantic. On August 28, the wave spawned a northward-moving vortex in the eastern Atlantic, but the wave's southern portion continued westward with very limited convective activity. Once the wave reached the western Caribbean Sea on September 5, the shower activity increased and the whole system continued slowly westward over Central America. The cloud pattern gradually became better organized and by September 9, satellite images showed a low to middle-level circulation centered near Acapulco, Mexico. The next day, a portion of the system moved over water and it became a tropical depression about south-southwest of Acapulco on September 10.

Tropical Depression One-C

Tropical Depression One-C formed on September 11 more than southeast of the Big Island of Hawaii. The system moved west-northwestward to 15°N 153°W initially, and then shifted southwestward shortly thereafter. A poorly organized system, the convection of Tropical Depression One-C dissipated later on September 11, after having been a depression for only 12 hours.

Hurricane Juliette

An area of disturbed weather associated with the remnants of Atlantic Tropical Depression Nine organized directly into Tropical Storm Juliette in the East Pacific on September 21. Moving generally northwestward under the influence of a mid-level ridge to the north, Juliette strengthened, aided by a low wind shear environment. It became a hurricane the next day, and rapidly intensified to a Category 4 hurricane on September 23. A pinhole eye appeared on the 24th, and Juliette reached peak intensity on September 25 with winds and a minimum barometric pressure of 923 millibars. Juliette developed rare concentric eyewalls as it reached peak intensity, which persisted from September 24 to the 27th. On September 26, Juliette turned northward around a strong trough over the western United States and began to weaken. Passing just west of Cabo San Lucas on September 28 with winds, it made landfall near San Carlos as a minimal tropical storm two days later. Juliette crossed the Baja California Peninsula into Gulf of California as a tropical depression and dissipated over the far northern part of the gulf on October 3. The total estimated cost of damage was $400 million (2001 USD; $  USD).

Hurricane Kiko

A tropical wave that led to the formation of Atlantic Hurricane Felix over the eastern Atlantic on September 7 also seems to have produced Kiko. This wave moved westward at low latitudes, crossing northern South America and Central America into the East Pacific from September 13 to 16. By September 17, cloudiness and showers increased near the Gulf of Tehuantepec. The area of disturbed weather moved westward for the next few days, without much increase in organization. On September 21, the system's cloud pattern became more consolidated, and curved bands of showers were evident. It is estimated that Tropical Depression Twelve-E had formed that day, at which time it was centered about southwest of the southern tip of Baja California.

Tropical Depression Two-C

Tropical Depression Two-C formed near 10°N 147.4°W on September 22, southwest of Tropical Storm Kiko (in the East Pacific). Throughout September 23, Tropical Depression Two-C remained a poorly organized system that slowly moved west-northwestward. A slight increase in convection became apparent on September 24, and was followed by a period of consistent thunderstorm activity near the circulation center as the depression continued in the west-northwest direction. The system dissipated during September 25.

Tropical Storm Lorena

The tropical wave that eventually developed into Lorena moved off the west coast of Africa on September 13. The poorly defined wave tracked rapidly westward across the Atlantic for more than a week. There was little or no thunderstorm activity associated with the wave until it moved across Central America on September 27. Significant deep convection finally developed on September 29 and satellite classifications began on September 30 when the system was located about south of Acapulco, Mexico. The wave possessed a well-defined closed low-level circulation at that time.

Tropical Depression Fourteen-E

Tropical Depression Fourteen-E developed from a small swirl of low clouds that was first observed along the Intertropical Convergence Zone well to the south-southwest of Baja California on September 30. Little development occurred until October 3, when the system began to generate more persistent deep convection. While the system was located about southwest of the southern tip of Baja California, the NHC began to classify it as Tropical Depression Fourteen-E. Although it appeared that wind shear was at initially predicted to remain at a favorable level, an upper-level low to the southwest of the depression generated wind shear greater than expected, and convection significantly weakened only hours later. Despite significant effects from wind shear, the depression was still forecast to intensify into a tropical storm. Later that day, the low-level center of the depression became more difficult to locate on satellite images, and the location of the poorly defined center was estimated. Convection significantly decreased again early on October 4, and the depression dissipated southwest of the southern tip of Baja California. The remnant low cloud swirl continued westward for another 24–36 hours before dissipating completely.

Hurricane Narda

Narda developed from a westward moving tropical wave that crossed Dakar, Senegal around the October 3. The wave became convectively active after it crossed Central America when it produced a large burst of convection in the Bay of Campeche on the October 15. The southern portion of the wave continued westward over the Pacific waters south of Mexico and under favorable upper-level winds, it began to acquire banding features and several centers of circulation. The system finally consolidated and developed one center at October 20. It became a tropical depression about southwest of Cabo San Lucas, Mexico. Moving on a west-northwest track, it intensified and reached tropical storm status later that day. The cloud pattern continued to become better organized and visible satellite imagery showed an intermittent eye feature, and it is estimated that Narda became a hurricane at October 21. Narda peak's intensity of 980 mbar (hPa; ) occurred on October 22. Thereafter, a gradual weakening began and strong shear took a toll on Narda. The tropical cyclone became a tight swirl of low clouds with intermittent convection on October 24, as it moved westward steered by the low-level flow and crossing 140°W over the Central Pacific area of responsibility. It then continued westward as a tropical depression until dissipation.

Hurricane Octave

The final tropical depression of the season likely developed from a weak tropical wave that moved westward across Central America on October 22. Following an area in convection on October 27 and the formation of a low-level circulation, the system was declared a tropical depression at 00:00 UTC on October 31, while centered about southwest of the southern tip of Baja California. The depression was initially affected by easterly upper-level winds and outflow was restricted on the eastern quadrant. The depression intensified and was upgraded to Tropical Storm Octave six hours after forming. Although cloud tops warmed on October 31, Octave organized further, and the NHC noted that the storm began to resemble a hurricane early on November 1. Shortly thereafter, no significant intensification was predicted, as the cloud pattern was becoming elongated, vertical wind shear would soon increase, and Octave would soon entering a region of decreasing sea surface temperatures. However, Octave re-organized and an eye feature began developing later on November 1.

The storm was upgraded to a hurricane after a ragged eye developed and T-numbers reached 4.0 on the Dvorak Scale. Early on November 2, Octave attained its peak intensity with maximum sustained winds of and a minimum barometric pressure of 980 mbar (hPa; ). However, the storm remained a hurricane until 18:00 UTC on November 2. The NHC downgraded the system to a tropical depression later that day. Deep convection associated with Octave remained minimal, and the system had degenerated into a remnant low located about west-southwest of the southern tip of Baja California at 00:00 UTC on November 4. This is the same list used for the 1995 season except for Ivo, which ultimately replaced Ismael. A storm was named Ivo for the first time in 2001.

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Adolph
Barbara*
Cosme
Dalila
Erick
Flossie
Gil
Henriette

Ivo
Juliette
Kiko
Lorena
Manuel
Narda*
Octave

For named storms that form in the North Pacific between 140°W and the International Date Line, the names come from a series of four rotating lists. Names are used one after the other without regard to year, and when the bottom of one list is reached, the next named storm receives the name at the top of the next list.

Retirement

After the 2001 season had begun the name Adolph was retired, and Israel, the original replacement for Ismael, was permanently withdrawn, both for political considerations, after controversy arose over their use. Adolph, already used in 2001, was replaced with Alvin starting with the 2007 season, while Israel was replaced with Ivo before having to take a turn in the 2001 name rotation.

Season effects

This is a table of all of the tropical cyclones that formed in the 2001 Pacific hurricane season. It includes their name, duration (within the basin), peak classification and intensities, areas affected, damage, and death totals. Deaths in parentheses are additional and indirect (an example of an indirect death would be a traffic accident), but were still related to that storm. Damage and deaths include totals while the storm was extratropical, a wave, or a low, and all of the damage figures are in 2001 USD.

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References

External links

National Hurricane Center Website
Servicio Meteorológico Nacional Website
NHC 2001 Pacific hurricane season archive
HPC 2001 Tropical Cyclone Rainfall Pages
Central Pacific Hurricane Center