Tropical Storm Dean was the fourth named storm of the 2001 Atlantic hurricane season. Dean formed on August 22 just east of Puerto Rico from a tropical wave. Dean moved northwest and quickly dissipated on August 23 because of strong upper-level wind shear. On August 26, Dean re-generated, then moved northeast and out to sea. Dean peaked as a 70 mph tropical storm with a pressure of 994 mb. Dean became extratropical on August 28. The precursor wave to Dean dropped heavy rainfall and caused moderate damage in the Lesser Antilles, but damage was not serious. In Puerto Rico, Dean produced rainfall up to 12.7 inches, which caused widespread flooding across the island. Thousands of homes were left without power and water as a result of Dean, and two homes lost their roofs. Dean caused light to moderate rainfall in Bermuda and Newfoundland, but caused no damage in those places.
Dean caused $7.7 million (2001 USD) in damage, but caused no fatalities.
|Formation||August 22, 2001|
|Dissipation||August 28, 2001|
|Highest winds||70 mph|
|Lowest pressure||994 mbar|
|Damages||$7.7 million (2001 USD)|
|Areas affected||Lesser Antilles, Virgin Islands, Puerto Rico, Bahamas, Bermuda, Atlantic Canada|
A large tropical wave with limited convection moved off the coast of Africa between August 14 to August 15 near Dakar. The wave moved westward across the Atlantic Ocean, and convection gradually increased along the wave axis. On August 21, while the wave was located about 450 miles east of the Lesser Antilles, convection increased further, although strong upper-level wind shear prevented rapid development. The wave continued to become better organized, and although a reconnaissance aircraft flight reported strong winds within the wave, there was no well-defined circulation center. Late on August 21, the wave passed through the Lesser Antilles. At this time, vertical wind shear decreased, and a surface circulation developed on August 22. Based on this, the wave was promptly upgraded to Tropical Storm Dean while located near the island of St. Croix. The reason Dean skipped depression status was because it contained tropical storm-force winds upon being classified. After forming, Dean moved northwest under the influence of the subtropical ridge to its northeast. Late on August 22, Dean strengthened to reach 60 mph winds, although the circulation was exposed on the western edge of the convection because of Dean's fast foward speed as well as strong upper-level shear.
Initially, it was forecast that Dean would become a hurricane with winds of 80 mph because of a decrease in vertical shear. However, upper-level trough caused an increase in shear, and by August 23, Dean had weakened to a tropical depression. Hours later, Dean's circulation dissipated, and it degenerated into a tropical wave east of the Bahamas. At the time, regeneration of Dean was considered unlikely by the National Hurricane Center. Dean's remnants turned north, and they became embedded within a large mid-level trough off the East Coast of the United States. Early on August 24, convection increased in association with Dean's remnants. Dean's remnants continued to become better organized, and there were indications of a broad surface circulation forming about 400 miles west-southwest of Bermuda. Despite this, a reconnaissance flight into the remnants of Dean reported a broad low-pressure area with the strongest winds and convection located far from the area of minimum pressure, indicating it had some non-tropical characteristics. Early on August 25, the disturbance passed west of the island of Bermuda, then began to recurve to the northeast.
Dean's remnants continued to organize convection around the low-level circulation center. On August 26, while located 220 miles north of Bermuda, the remnants organized enough to warrant classifying the system as a tropical depression. Operationally, the National Hurricane Center did not re-initiate advisories until 15 hours later. Dean continued northeast, and re-strengthened into a tropical storm early on August 27 while located 580 miles south of Halifax, Nova Scotia. Dean continued northeast, steadily strengthening as convection continued to increase. A ship near Dean's center confirmed that Dean did re-develop. Convection became much better organized near Dean's center, and an eye-like feature developed. Because Dean remained over warm waters, it strengthened to reach a peak of 70 mph winds late on August 27, while located about 465 miles southwest of Cape Race, Newfoundland. The eye failed to develop further, and after maintaining peak intensity for 12 hours, Dean began to weaken over progressively cooler waters. Convection with Dean quickly diminished, and late on August 28, Dean became an extratropical cyclone about 145 miles east-southeast of Cape Race, Newfoundland. Dean's extratropical remnants continued northeast until being absorbed by a frontal low on August 29.
Dean south of Nova Scotia.
About a day before Dean developed, the National Hurricane Center advised residents in the central and northern parts of the Lesser Antilles to monitor the progress of the system. Also, routine statements by the NHC warned of strong winds and heavy rain. But because Dean formed after it passed the islands, no watches or warnings were issued for the Lesser Antilles.
In the Bahamas, the government issued a Tropical Storm Warning for the southeastern portion of the Bahamas as well as the Turks & Caicos Islands. The threat from Dean resulted in in the cancellation of several flights in and out of Providenciales. When Dean weakened and ultimately dissipated, all warnings were dropped. Dean had no impact on the Bahamas.
The precursor wave to Dean dropped heavy rainfall across the Lesser Antilles, including 1.5 inches of rain in Nevis. On the island of Antigua, the precursor wave produced 30 to 35 mph winds, with gusts over 50 mph on the higher terrain. In Saba, the wave produced rainfall around 1 inch. Due to the threat of mudslides, several schools were closed early. Officials at the Juancho E. Yrausquin Airport cancelled several flights due to the system. Also, rough seas in Saba caused many ships and boats to remain at port. The wave also dropped heavy rainfall in St. Martin, peaking around 5 inches, which caused flooding in some low-lying areas. Because of the threat from the then tropical wave, schools were advised to close early, and officials enacted preparations to reduce flooding. High waves on the southern portion of the island broke a cargo vessel from its moorings and washed it ashore. On the island of Tortola, heavy rain and strong winds left houses without cable, although no damage was reported on the island. On the island of Saint Thomas, the precursor wave produced about 1.07 inches of rain. Sustained winds were 40 mph, gusting to 48 mph. In addition, 6-8 foot seas caused disruption in coastal waters of the United States Virgin Islands. On the island of St. Croix, the wave produced a peak wind gust of 47 mph and it also dropped 0.49 inches of rain. Minor flooding was reported there. Also, moderate wind gusts from the wave downed small trees and branches in St. Croix and St. John, with some roads being damaged on St. John. Heavy rainfall and gusty winds caused power outages throughout the U.S. Virgin Islands. Total damage from Dean in the Leeward Islands resulted in minor damage totaling to $20,000 (2001 USD).
Tropical Storm Dean shortly after forming.
Dean dropped heavy rainfall in Puerto Rico, peaking at 12.7 inches in Salina. Despite the heavy rain, winds were fairly light in the country. Dean's passage caused widespread flooding in the eastern and southern portions of Puerto Rico, causing the collapse of two bridges and one road. Several highways were underwater, and one car was swept away by floodwaters. The four people inside the vehicle were later rescued, and, thankfully, unharmed. Throughout the country, 1,320 homes were flooded, and two houses had their roofs totally collapsed. Also, the heavy rains from Dean left various towns in the country without electricity or water. By the night after Dean passed the island, more than 16,000 residents were without power, and almost 70,000 people lacked potable water. Also, 130 people were evacuated from low-lying areas and moved to shelters. Two people were injured in Peñuelas, and three people were injured in Nagüabo when the ceiling of a day care center collapsed. Despite all of this, no deaths occured in Puerto Rico from Dean. One airline cancelled 17 flights in and out of the island, and one cruise line was required to alter its path because of Dean. Also, earlier on in the month, that same ship had to change its course because of Tropical Storm Chantal. Total damage in Puerto Rico is estimated at $7.7 million (2001 USD), of which $2.1 million (2001 USD) was from agricultural damage.
Dean's remnants produced a 41 mph wind gust in Bermuda. Also, rainfall was reported at 0.31 inches. Also, Dean's passage resulted in the coolest day during the entire month of August in 2001.
In Newfoundland, Dean produced wind gusts of 63 mph, along with heavy rainfall of 4.2 inches in eastern Newfoundland. On land, waves reached 30 feet, and a buoy offshore repoted waves as high as 47 feet.