The 2001 Atlantic hurricane season was a fairly active Atlantic hurricane season that produced 17 tropical cyclones, 15 named storms, nine hurricanes, and four major hurricanes. The season officially lasted from June 1 to November 30, 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 5, and ended with Hurricane Olga, which dissipated on December 6.
The most damaging storms of the season were Allison, which caused extensive flooding in Texas; Hurricane Iris, which struck Belize; and Hurricane Michelle, which left a trail of destruction across Cuba. Three tropical cyclones made landfall in the United States, three directly affected Canada, and three directly affected Mexico and Central America. Overall, the season caused 148 fatalities, and $11.45 billion (2001 USD) in damage. Due to their severe damage, the names Allison, Iris, and Michelle were retired by the World Meteorological Organization.
Similar to the previous season, of the three cyclones (Allison, Barry, and Gabrielle) that made landfall in the United States, none achieved higher than tropical storm status.
Seasonal forecasts
Forecasts of hurricane activity are issued before each hurricane season by noted hurricane experts William M. Gray. Philip J. Klotzbach, and their associates at Colorado State University; and separately by NOAA forecasters.
Gray's team defined the average number of storms per season (1950 to 2000) as 9.6 tropical storms, 5.9 hurricanes, 2.3 major hurricanes (storms reaching at least Category 3 strength in the Saffir-Simpson Hurricane Scale) and ACE Index 96.1. The National Oceanic and Atmospheric Administration (NOAA) defines a season as above-normal, near-normal or below-normal by a combination of the number of named storms, the number reaching hurricane strength, the number reaching major hurricane strength and ACE Index.
Pre-season forecasts
On December 7, 2000, Gray's team issued its first extended-range forecast for the 2001 season, predicting above-average activity (13 named storms, 8 hurricanes, and about 4 of Category 3 or higher). It listed a 63 percent chance of at least one major hurricane striking the U.S. mainland. This included a 43 percent chance of at least one major hurricane strike on the East Coast, including the Florida peninsula, and a 36 percent chance of at least one such strike on the Gulf Coast from the Florida Panhandle westward. The potential for major hurricane activity in the Caribbean was forecast to near average.
On April 5, 2001, a new forecast was issued, calling for 12 named storms, 7 hurricanes, and 3 major hurricanes. The increase in the forecast was attributed to the warm sea surface temperatures, although the agency noted that the season would likely not be as active as previous ones due to the effect of a weak to moderate El Nino. The estimated potential for at least one major hurricane to affect the U.S. was upped slightly to 65 percent; the East Coast potential also went up slightly, and from the Florida Panhandle westward to Brownsville, Texas, the probability remained nearly the same.
Mid-season forecasts
On August 7, 2001, Gray's team issued their first mid-season forecast for the 2001 season, keeping the forecast number at 12 named storms, with 7 becoming hurricanes and 3 becoming a major hurricane, noting that sea surface temperatures and sea level pressures continued to be favorable for above-average hurricane activity. The estimated potential for at least one major hurricane to affect the U.S. was upped slightly once again to 69 percent; the East Coast potential also went up slightly to 50%, and from the Florida Panhandle westward to Brownsville, Texas, the probability was also upped slightly.
On August 8, 2001, NOAA revised its season estimate slightly upwards to nine to twelve named storms, of which 6 to 8 were to be hurricanes, and 2 to 4 major hurricanes. The agency noted that sea surface temperatures continued to be favorable for above-average hurricane activity, and due to the likelihood that El Nino would not develop during the peak of the season, there was a reduced likelihood of a below-average year.
Seasonal summary
The Atlantic hurricane season officially began on June 1, 2001. It was an above-average season in which 17 tropical cyclones formed. Fifteen depressions attained tropical storm status, and nine of these reached hurricane status. Four hurricanes further intensified into major hurricanes. Favorable sea surface temperatures and sea-level pressures were the main factors in the season being above-average. The season was the fourth, and final, above-average season in a row. This streak set a record that stood until six consecutive seasons featured above-average activity from 2016 to 2021. Four tropical cyclones during the season would degenerate in the deep tropics but later re-develop. Four other systems were classified as subtropical cyclones at some point in their duration, though each later became fully tropical systems. Overall, the Atlantic tropical cyclones of 2001 collectively resulted in 148 deaths and around $11.45 billion in damage. The season ended on November 30, 2001.
Tropical cyclogenesis began in June, with Tropical Storm Allison forming just offshore Texas on June 5. After Allison transitioned into an extratropical cyclone on June 17, no further activity occurred until Tropical Depression Two developed on July 11. However, the depression dissipated the following day. Another break in activity ensued, which ended on August 2, when Tropical Storm Barry formed in the Gulf of Mexico. August featured two other tropical storms, Chantal and Dean.
Five systems formed in September, of which four become a hurricane, while one remained a tropical depression. October featured an equal number of systems, of which all five attained at least tropical storm intensity. One, Hurricane Iris, attained the highest sustained winds of any storm in 2001, at 145 mph (230 km/h), and devastated southern Belize on October 9. Another, Hurricane Michelle, attained the lowest barometric pressure of any storm that year, at 933 mbar (27.55 inHg), and cut a path of destruction across Cuba on November 4. Two additional systems developed in November, Hurricane Noel and Hurricane Olga. Olga dissipated on December 4, ending seasonal activity.
The season's activity was reflected with an accumulated cyclone energy (ACE) rating of 110, above the 1950–2000 average of 96.1. 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. It is only calculated for full advisories on tropical systems at or exceeding 39 mph (63 km/h), which is the threshold for tropical storm status.
Systems
Tropical Storm Allison
A tropical wave over the northwestern Gulf of Mexico developed into Tropical Storm Allison at 12:00 UTC on June 5 about 140 mi (225 km) south of Galveston, Texas. The cyclone strengthened and peaked six hours later with winds of 60 mph (95 km/h) and a minimum atmospheric pressure of 1,000 mbar (30 inHg). At 21:00 UTC on June 5, Allison made landfall near Freeport, Texas. It drifted northward through the state, turned to the south, and re-entered the Gulf of Mexico as a tropical depression on June 10. Allison then transitioned into a subtropical depression. The storm continued towards the east-northeast, made landfall on Louisiana early on June 11, and briefly became a subtropical storm despite being inland. Crossing the southeast United States and Mid-Atlantic, Allison emerged into the Atlantic at the Delmarva Peninsula on June 17. After temporarily re-attaining subtropical storm status, Allison interacted with a cold front offshore New England and became extratropical. Early on June 19, the remnant extratropical low dissipated near Nova Scotia.
Allison was the first storm since Tropical Storm Frances in 1998 to affect the northern Texas coastline. A major flood disaster occurred throughout its path and nearby areas from Texas to New England. The Greater Houston area of Texas suffered the brunt of the impact, as over 35 in (890 mm) of rain fell there when Allison stalled over the southeastern part of the state. In this area, flooding related to Allison destroyed or severely damaged more than 14,000 homes, while at least 51,430 others experienced some degree of damage. Floodwaters also entered over 95,000 vehicles and 1,700 businesses. The storm killed 50 people, including 27 who drowned. Overall, Allison caused about $8.5 billion in damage (2001 USD), making it the costliest and second-deadliest tropical storm on record in the United States.
Tropical Depression Two
A tropical wave emerged into the Atlantic from the west coast of Africa on July 7. Moving westward, the system displayed signs of a weak low-level circulation beginning on July 10, and after deep convection formed on the following day, a tropical depression developed around 18:00 UTC about 1,150 mi (1,850 km) east of the Windward Islands. A subtropical ridge north of the depression caused it to move west-northwestward at roughly 17 mph (27 km/h). Vertical wind shear prevented the cyclone from intensifying beyond sustained winds of 30 mph (45 km/h) and an atmospheric pressure of 1,010 mbar (30 inHg), with dissipation occurring late on July 12 approximately 690 mi (1,110 km) east of the Windward Islands. The remnant tropical wave reached the Lesser Antilles on July 13 and July 14.
Tropical Storm Barry
On July 24, a tropical wave moved off the coast of Africa and tracked westward. The wave entered the Caribbean Sea on July 29 and gained in organization and convection, before reaching the Gulf of Mexico on August 1. By the following day, a tropical depression developed about 200 mi (320 km) west-northwest of Key West, Florida, and soon strengthened into Tropical Storm Barry. After fluctuations in intensity, including when it weakened to a tropical depression on August 4, the system attained peak winds of 70 mph (110 km/h) in the Gulf of Mexico late on August 5. Around 05:00 UTC on the next day, Barry made landfall near Santa Rosa Beach, Florida, at the same intensity. The storm weakened to a tropical depression over southern Alabama about seven hours later, before degenerating into a remnant low over Mississippi early on August 7. The remnant low continued north-northwestward until dissipating over Missouri on August 8.
The tropical wave that developed into Barry generated rough seas over the Straits of Florida, capsizing a boat of Cuban refugees, six of whom drowned. Barry's precursor also dropped heavy rain over South Florida, peaking at 11.7 in (300 mm) near Stuart, damaging about 300 homes in Martin County, 69 severely. In the Florida Panhandle, rainfall reached 8.9 in (230 mm) in Tallahassee, and winds gusts topped out at 79 mph (127 km/h). Winds caused damage to some homes and downed trees, while floodwaters inundated streets and entered some cars and structures. Three people in Florida were killed by the storm, and total damage is estimated at $30 million (2001 USD). Several other states in the South reported rainfall.
Tropical Storm Chantal
A westward-moving tropical wave organized into a tropical depression about 1,500 mi (2,400 km) east of the Windward Islands on August 14. The depression moved rapidly westward and degenerated into an open wave sometime on August 16 while still well east of the Windward Islands. However, after reaching the southeast Caribbean, a circulation re-developed while the system was situated 290 mi (470 km) south of Saint Croix on August 17. With tropical storm-force winds, the system was reclassified as Tropical Storm Chantal. The cyclone strengthened to reach sustained winds of 70 mph (110 km/h) twice in the Caribbean; Chantal's atmospheric pressure also fell to 997 mbar (29.4 inHg) on August 19. Early on August 21, Chantal made landfall near the Belize–Mexico border with winds of 70 mph (110 km/h). The cyclone weakened to a tropical depression over Campeche on August 22, before dissipating over Tabasco several hours later.
The tropical wave associated with Chantal caused two deaths in Trinidad due to a lightning strike. In Belize, abnormally high tides along the coast damaged piers and seawalls. The storm produced a wind gust of 71 mph (114 km/h) in Caye Caulker, although stronger winds were possible in a convective band to the north. Winds and flooding due to heavy rainfall left damage to agricultural and infrastructural sectors. Overall, Belize suffered nearly $4 million in damage. Heavy rain fell in parts of Mexico, particularly in Quintana Roo, with up to 20.03 in (509 mm) observed at Othón P. Blanco. This led to mudslides, leaving some areas isolated.