2001 Atlantic hurricane season

The 2001 Atlantic hurricane season was a fairly active Atlantic hurricane season that produced 17 tropical cyclones, 15 named storms, 9 hurricanes, and 4 major hurricanes. The season officially lasted from June 1, 2001, to November 30, 2001, dates which by convention limit the period of each year when tropical cyclones tend to form in the Atlantic Ocean basin. The season began with Tropical Storm Allison on June 4, and ended with Hurricane Olga, which dissipated on December 6. The most intense storm was Hurricane Michelle, which attained Category 4 strength on the Saffir-Simpson Hurricane Scale.

The most damaging storms of the season were Tropical Storm Allison, which caused extensive flooding in Texas, Hurricane Iris which struck Belize, and Hurricane Michelle, which affected several countries. Three tropical cyclones made landfall on the United States, three directly affected Canada, and three directly affected Mexico and Central America. Overall, the season caused 105 fatalities, and $7.1 billion (2001 USD; $8.6 billion 2008 USD) in damage. Due to their severe damage, the names Allison, Iris, and Michelle were retired by the World Meteorological Organization.

Storms

June–August

Tropical Storm Allison developed from a tropical wave in the northern Gulf of Mexico on June 4, 2001, and struck the northern Texas coast shortly thereafter. It drifted northward through the state, turned to the south, and re-entered the Gulf of Mexico. The storm continued towards the east-northeast, made landfall on Louisiana, then moved across the southeast United States and Mid-Atlantic.¹ Allison was the first storm since Tropical Storm Frances in 1998 to affect the northern Texas coastline.²

A tropical depression formed from a low level circulation on July 11, well to the east of the Windward Islands. It attained a maximum strength of 30 mph (48 km/h), with a pressure of 1010 mbar, though vertical wind shear from a subtropical ridge to the north caused it to dissipate on July 12.³

On July 24, a tropical wave moved off the coast of Africa and tracked westward. The wave entered the Caribbean on July 29 and gained in organization and convection, and organized into Tropical Storm Barry on August 3. After fluctuations in intensity, the system attained peak winds of 70 mph (110 km/h) in the Gulf of Mexico, and headed northward before moving ashore along the Gulf Coast.⁴

Tropical Storm Chantal developed from a tropical wave on August 14 in the tropical Atlantic Ocean. It tracked rapidly westward for much of its duration, and after degenerating into a tropical wave it passed through the Windward Islands. Chantal reformed and reached a peak intensity of 70 miles per hour (110 km/h) twice in the Caribbean Sea, and each time, wind shear and later land interaction prevented strengthening to hurricane status. On August 21 Chantal moved ashore near the border of Mexico and Belize, and it dissipated the next day.⁵

A tropical wave spawned Tropical Storm Dean on August 22 over the Lesser Antilles. Strong wind shear quickly weakened Dean to cause it to dissipate on August 23. The remnants turned northward, and redeveloped on August 26 to the north of Bermuda. Located over warm waters and in an area of favorable conditions, Dean steadily strengthened while moving to the northeast, and peaked just below hurricane status on August 27 southwest of Newfoundland. The storm subsequently weakened over cooler waters, and became extratropical on August 28.⁶

September

Hurricane Erin developed from a tropical wave on September 1, and strengthened to a 60 mph (95 km/h) tropical storm as it moved to the west-northwest. After weakening due to wind shear, the remnants re-organized into a tropical depression the next day, and Erin strengthened into a hurricane on September 9 while moving northwestward. The hurricane quickly intensified and reached peak winds of 120 mph (195 km/h) later on September 9. A trough turned Erin to the northeast, and after passing just east of Cape Race, Newfoundland it became extratropical on September 15. The extratropical remnant continued northeastward and lost its identity near Greenland on September 17.⁷

A tropical wave off the coast of Africa organized into Tropical Depression Seven on September 7 while near the Cape Verde islands. It moved rapidly to the west, and degenerated to a tropical wave the next day. By September 10, the wave had reorganized, and it was again named Tropical Depression Seven. The depression continued to strengthen, and became Hurricane Felix by September 13. Tracking roughly northward, Felix intensified rapidly, reaching Category 3 status, and subsequently turned to the north as it began to weaken. By September 17, Felix had dropped to tropical storm strength, and it dissipated two days later.⁸

Hurricane Gabrielle originated in a weak low- to mid-level trough that was nearly stationary a short distance off the southeastern coastline of the United States. A cut off low formed over Florida on September 9, and an associated surface low pressure system formed, that was soon designated Tropical Depression Eight. The storm gradually intensified, and made landfall on Florida before emerging into the Atlantic Ocean and accelerating northeastward, as it reached peak intensity as a minimal hurricane.⁹

A tropical depression formed from a tropical wave in the Caribbean on September 19, north-northwest of San Andres Island. It attained a maximum strength of 35 mph (56 km/h), and made landfall near Puerto Cabezas on September 20. After losing its closed circulation over land, it reformed into Hurricane Juliette in the East Pacific.¹⁰

Hurricane Humberto formed from an area of low pressure generated by Hurricane Gabrielle. The low formed into a tropical depression on September 21 while south of Bermuda, tracking northwest, and was named Tropical Storm Humberto the next day. It began moving north, and then northeast as it passed Bermuda and strengthened into a hurricane. Humberto headed over the colder waters of the far north Atlantic Ocean, and dissipated quickly on September 27.¹¹

Tropical Depression Eleven formed just southeast of Barbados on October 4. It traveled across the Windward Islands, and was named Tropical Storm Iris while south of Puerto Rico on the 5th. Iris continued to the west and intensified. After passing just south of Jamaica, Iris reached Category 4 hurricane strength, and made landfall near Monkey River Town, Belize on October 9 at Category 4 strength, but weakened rapidly. It dissipated later that day.¹²

October and November

Tropical Storm Jerry formed as a tropical depression from a tropical wave on October 6 near Barbados. The storm intensified into a tropical storm early the following day on October 7 while initially located under an environment of weak vertical wind shear. After reaching its peak of 50 mph (80 km/h), Jerry passed just south of Barbados late on October 7 and through the Windward Islands on October 8. Deterioration in organization occurred, and Jerry dissipated while moving rapidly westward well south of Puerto Rico.¹³

A cold front and an upper level trough interacted on October 10 to the south of Bermuda, and formed an extratropical storm. The storm passed near Bermuda on October 12, producing hurricane-force winds on the island. It then organized, becoming a subtropical cyclone on the 12th and a tropical cyclone on the 13th. Karen strengthened to reach 80 mph (130 km/h) winds as a Category 1 hurricane on the Saffir-Simpson Hurricane Scale, and after weakening over cooler waters, it made landfall on Nova Scotia as a tropical storm. It quickly became extratropical.¹⁴

An upper-level tropospheric trough persisted in the eastern Atlantic Ocean, developing a low-level circulation by October 26 which quickly gained organization. On October 27, the low developed into Tropical Depression Fourteen about 860 miles (1380 kilometers) south-southwest of the western Azores, and on October 30 it was upgraded to Tropical Storm Lorenzo. By early on October 31 Lorenzo became extratropical and merged with a frontal system.¹⁵

Hurricane Michelle developed from a tropical wave that moved across the Atlantic, and formed into atropical depression on October 29. Convection increased, and the system formed into Tropical Storm Michelle on November 1. It strengthened further, reaching its peak strength as a Category 4. One of only four November Category 4 hurricanes, Michelle made landfall on south-central Cuba with winds of 140 mph (225 km/h), the strongest Cuban landfall since Hurricane Fox in the 1952 Atlantic hurricane season.¹⁶

Hurricane Noel developed as a subtropical cyclone from a frontal low on November 4 to the west of the Azores. It moved northward, and following an increase in deep convection it transitioned in Hurricane Noel on November 5. Noel quickly weakened as it entered an area of cooler waters and higher wind shear, and it became an extratropical cyclone on November 6 to the southeast of Newfoundland. The extratropical remnant of Noel was absorbed by a larger extratropical storm which absorbed the remnants of Hurricane Michelle, and intensified as it moved westward into Atlantic Canada, reaching pressures as low as 946 mbar.¹⁷

Hurricane Olga formed as a subtropical cyclone on November 24 and meandered westward where it reached hurricane status on November 26. The storm attained peak winds of 90 mph (150 km/h) before turning southeastward and weakening back into a tropical storm. Olga dissipated as a tropical cyclone on December 6 east of the Bahamas.¹⁸

Impact

The 2001 season was severe in terms of damages. The most noteworthy storms include Tropical Storm Allison, Hurricane Iris, and Hurricane Michelle. The United States was directly affected by three tropical cyclones, the first of which was Allison. Tropical Storm Allison was a major flood disaster throughout its path from Texas to the Mid-Atlantic. The worst of the flooding occurred in Houston, Texas, where over 35 inches (890 mm) of rain fell. The storm killed 41 people, of which 27 drowned. The storm also caused over $5 billion in damage (2001 USD, $6.4 billion 2007 USD), making it the deadliest and costliest tropical storm on record in the United States.¹ Allison destroyed 2,744 homes, leaving 30,000 homeless with residential damages totaling to $1.76 billion (2001 USD, $2.05 billion 2007 USD).¹⁹ Tropical Storm Barry affected Florida; rainfall peaked at 8.9 in (230 mm) at Tallahassee, and winds gusts topped out at 79 mph (127 km/h).⁴ Three people in Florida were killed by the storm, and total damage is estimated at around $30 million (2001 USD, $36.5 million 2008 USD).²⁰ Later, Hurricane Gabrielle produced moderate winds along coastal areas of western Florida, reaching 58 mph (93 km/h) at Venice.⁹ The tide flooded the northern shoreline of Charlotte Harbor and at the entrance to the Peace River, while further to the south a surge of greater than 3 feet (0.91 m) inundated the barrier island at Fort Myers Beach and flooded some cars.²¹

Canada was also affected by several storms. In August, Tropical Storm Dean lightly affected Newfoundland, though no damages were reported.⁶ Hurricane Erin brushed the same area, producing a sustained wind of 53 mph (85 km/h) with a gust of 67 mph (108 km/h) at Cape Race.⁷ Along the coast, the passage of the storm led to wave heights of up to 30 feet (9.3 m).²² Less than a week later, Hurricane Gabrielle brushed the eastern coast; the rainfall set the all time 6 hour precipitation record at St. John's, with a total of 3.54 inches (90 mm).²³ Hundreds of homes and buildings were damaged by the passage of Gabrielle, totaling several million dollars in damage.²⁴ Tropical Storm Karen produced light to moderate winds across Atlantic Canada, peaking at 47 mph (76 km/h) with a gust of 64 mph (103 km/h) in Cape George in Antigonish County, Nova Scotia, along with a 26 mph (42 km/h) report in Charlottetown, Prince Edward Island.¹⁴ Later, in Newfoundland and Nova Scotia, the storm system that absorbed Hurricane Noel produced strong winds that downed several trees and power lines which resulted in power outages.²⁵

Mexico and Belize were impacted by a number of storms, starting with Tropical Storm Chantal, which produced a wind gust of 71 miles per hour (115 km/h) in Caye Caulker, although stronger winds were possible in a convective band to the north.⁵ On the Yucatan Peninsula, heavy rainfall led to mudslides across Quintana Roo, leaving some areas isolated.²⁶ Hurricane Lili hit Belize hard, with an 8 to 15 ft (2.4 to 4.6 m) storm surge. Numerous homes were destroyed, and the banana crop suffered extensive damage. An exact death toll is unknown, but 31 are confirmed dead, 3 in the Dominican Republic, 8 in Guatemala, and 20 from the M/V Wave Dancer, a ship that capsized off the Belize coast.¹² What eventually became Hurricane Michelle dropped torrential rains in several countries, causing 6 deaths in Honduras and 4 deaths in Nicaragua, with an extensive yet unknown amount of damage. An additional 26 people were reported missing in Central America.¹⁶ Michelle went on to affect Cuba, where the storm produced 4 to 5 ft (1.2 to 1.5 m) waves, along with a heavy storm surge. Rainfall amounts up to 754 mm (29.69 in) were recorded across the island.²⁷

Accumulated Cyclone Energy (ACE) Ranking

The table on the right shows the Accumulated Cyclone Energy (ACE) for each storm in the season. ACE is, broadly speaking, a measure of the power of the hurricane multiplied by the length of time it existed, so storms that last a long time, as well as particularly strong hurricanes, have high ACEs. ACE is only calculated for full advisories on tropical systems at or exceeding 34 knots (39 mph, 63 km/h) or tropical storm strength. The highest ever ACE estimated for a single storm in the Atlantic is 73.6, for Hurricane San Ciriaco in the 1899 Atlantic hurricane season. This single storm had an ACE higher than many whole Atlantic storm seasons, like this one. Other Atlantic storms with high ACEs include Hurricane Ivan of the 2004 Atlantic hurricane season, with an ACE of 70.4, and Hurricane Donna in the 1960 Atlantic hurricane season, with an ACE of 64.6.²⁹

Of the storms, Hurricane Erin had the highest ACE, at 20.12, followed by Michelle at 15.65. Hurricane Felix had a total ACE of 15.22, and Olga ranked fourth-highest, at 10.64. Despite being one of most notable storms of the season, Tropical Storm Allison had the lowest rating, with an ACE of 0.61. Allison was only one of two storms below 1 point, the other being Tropical Storm Lorenzo at 0.74.²⁸

Season impact

Storm names

The following names were used for named storms that formed in the north Atlantic in 2001. The names not retired from this list will be used again in the 2007 season. This is the same list used for the 1995 season except for Lorenzo, Michelle, Olga, and Rebekah, which replaced Luis, Marilyn, Opal, and Roxanne. Storms were named Lorenzo, Michelle, and Olga for the first time in 2001.³⁰ Names that were allocated for the 2001 season but were not assigned are marked in gray.

Retirement

The World Meteorological Organization retired three names in the spring of 2002: Allison, Iris, and Michelle. They were replaced in the 2007 season by Andrea, Ingrid, and Melissa. Allison became the first Atlantic tropical storm to have its name retired.³¹

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