Tropical Storm Dean was a strong tropical storm that affected at least twelve islands along its path from the tropical

Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...

to east of

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in August 2001. Dean developed from a

tropical wave A tropical wave (also called easterly wave, tropical easterly wave, and African easterly wave), in and around the Atlantic Ocean, is a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, which ...

on August 22 over the

Lesser Antilles The Lesser Antilles is a group of islands in the Caribbean Sea, forming part of the West Indies in Caribbean, Caribbean region of the Americas. They are distinguished from the larger islands of the Greater Antilles to the west. They form an arc w ...

, and was initially predicted to intensify further to reach hurricane status. However, strong

wind shear Wind shear (; also written windshear), sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical ...

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 Bermuda is a British Overseas Territories, British Overseas Territory in the Atlantic Ocean, North Atlantic Ocean. The closest land outside the territory is in the American state of North Carolina, about to the west-northwest. Bermuda is an ...

. 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 about southwest of

Newfoundland Newfoundland and Labrador is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region of Labrador, having a total size of . As of 2025 the population ...

. The storm subsequently weakened over cooler waters, and became

extratropical Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are low-pressure areas which, along with the anticyclones of high-pressure areas, drive the weather over much of the Earth. Extratropical cyclones are capable of p ...

on August 28. The precursor tropical wave dropped heavy rainfall and produced moderate winds throughout the

, though no serious damage was reported. In

Puerto Rico ; abbreviated PR), officially the Commonwealth of Puerto Rico, is a Government of Puerto Rico, self-governing Caribbean Geography of Puerto Rico, archipelago and island organized as an Territories of the United States, unincorporated territo ...

, rainfall of up to produced widespread flooding across the island. Thousands were left without power or water, and two houses lost their roofs from the storm. The passage of Dean resulted in $7.7 million (2001 USD, $9.4 million 2008 USD) in damage in Puerto Rico. The storm produced light to moderate rainfall in

and later in

, though no damage was reported.

Meteorological history

A large tropical wave with minimal convection moved off the coast of

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near

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between August 14 and August 15. It moved westward, and gradually developed thunderstorms across the wave axis. On August 21, while located about east of the

, convection increased further within the system, though unfavorable upper-level

prevented rapid development. It continued to become better organized, and though a Reconnaissance flight into the system reported strong winds, it lacked a surface circulation. Late on August 21 the wave passed through the northern Lesser Antilles, and subsequent to a decrease in wind shear the system became much better organized on August 22. A surface circulation formed, and the system developed into Tropical Storm Dean on August 22 near

Saint Croix Saint Croix ( ; ; ; ; Danish language, Danish and ; ) is an island in the Caribbean Sea, and a county and constituent Districts and sub-districts of the United States Virgin Islands, district of the United States Virgin Islands (USVI), an Unin ...

. Dean was upgraded directly to a tropical storm due to the presence of winds in the storm. Reconnaissance Aircraft and surface reports confirmed the existence of a circulation. Dean moved northwestward at , under the influence of the

Bermuda High The Azores High also known as North Atlantic (Subtropical) High/Anticyclone or the Bermuda- High, is a large subtropical semi-permanent centre of high atmospheric pressure typically found south of the Azores in the Atlantic Ocean, at the Horse lat ...

to its northeast. The storm strengthened slightly to reach winds of later on August 22, though the circulation was exposed on the western edge of the convection due to the storm's quick forward motion and persistent

. Initial forecasts predicted the shear to decrease, allowing Dean to attain hurricane status with winds of over . However, an upper-level

trough Trough may refer to: In science * Trough (geology), a long depression less steep than a trench * Trough (meteorology), an elongated region of low atmospheric pressure * Trough (physics), the lowest point on a wave * Trough level (medicine), the l ...

produced an increase of shear over the storm, and by August 23 Dean weakened to a tropical depression. Hours later, the circulation dissipated, and Dean degenerated into a tropical wave to the east of the

Bahamas The Bahamas, officially the Commonwealth of The Bahamas, is an archipelagic and island country within the Lucayan Archipelago of the Atlantic Ocean. It contains 97 per cent of the archipelago's land area and 88 per cent of its population. ...

. Regeneration was considered unlikely at the time. The remnants of Dean turned to the north, and became embedded within a large mid-level trough off the

East Coast of the United States The East Coast of the United States, also known as the Eastern Seaboard, the Atlantic Coast, and the Atlantic Seaboard, is the region encompassing the coast, coastline where the Eastern United States meets the Atlantic Ocean; it has always pla ...

. Convection increased around the system early on August 24. The system became better organized, with indications of a broad surface circulation forming about west-southwest of

. However, a reconnaissance flight into the remnants of Dean reported a broad

low pressure area In meteorology, a low-pressure area (LPA), low area or low is a region where the atmospheric pressure is lower than that of surrounding locations. It is the opposite of a high-pressure area. Low-pressure areas are commonly associated with inclem ...

with the strongest winds and convection located far from the area of minimum pressure, indicating it had some non- tropical characteristics. The weak disturbance passed to the west of Bermuda early on August 25, and subsequently began to drift to the northeast. The remnants of Dean produced convection near its developing circulation, and on August 26, while located north of Bermuda the system organized sufficiently enough to be re-classified a tropical depression. Operationally, the

National Hurricane Center The National Hurricane Center (NHC) is the division of the United States' NOAA/National Weather Service responsible for tracking and predicting tropical weather systems between the IERS Reference Meridian, Prime Meridian and the 140th meridian ...

did not re-initiate advisories until fifteen hours later. The depression continued to the northeast, and re-strengthened into Tropical Storm Dean early on August 27 while located south of

Halifax, Nova Scotia Halifax is the capital and most populous municipality of the Provinces and territories of Canada, Canadian province of Nova Scotia, and the most populous municipality in Atlantic Canada. As of 2024, it is estimated that the population of the H ...

. The convection became better organized, and Dean steadily strengthened as it tracked northeastward. A ship near the center of Dean confirmed the storm re-developed. The convection near the center greatly organized, and an eye feature began to develop. Remaining over warm waters, Dean continued to strengthen and reached peak winds of late on August 27 while located about southwest of

Cape Race Cape Race is a point of land located at the southeastern tip of the Avalon Peninsula on the island of Newfoundland, in Newfoundland and Labrador, Canada. Its name is thought to come from the original Portuguese name for this cape, "Raso", mean ...

. The eye feature failed to develop further, and after maintaining its peak intensity for 12 hours Dean weakened over progressively cooler waters. The convection quickly diminished, and on August 28 Dean became

while located east-southeast of Cape Race, Newfoundland. The extratropical storm continued northeastward until being absorbed by a frontal low on August 29.

Impact and preparations

Caribbean

About a day before Dean developed, the National Hurricane Center advised interests in the northern and central

to monitor the progress of the storm. Routine statements issued by the National Hurricane Center warned for the possibility of strong winds and heavy rains. However, because Dean formed after it passed the islands, no tropical cyclone warnings or watches were issued. The precursor disturbance dropped heavy rainfall on

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of around . The precursor disturbance to Tropical Storm Dean produced of rain in Saint Thomas, where winds reached with gusts to . On

, the system produced of rain and peak wind gusts of . There, minor flooding was reported. Moderate wind gusts downed small trees and branches in Saint Croix and Saint John, and some roads were damaged in Saint John, as well. Heavy rains and gusty winds caused power outages throughout the U.S. Virgin Islands. The passage of Tropical Storm Dean resulted in minor damage totaling to $20,000 (2001 USD). Tropical Storm Dean dropped heavy rainfall across

, peaking at in Salinas. Winds were generally light across the island. The passage of Dean resulted in widespread flooding in eastern and southern Puerto Rico, collapsing two bridges and one road. Several highways were under water, and one car was swept away by the floodwaters. The four inside the vehicle were later rescued and unharmed. Throughout the island, about 1,320 houses were flooded, and two houses experienced collapsed roofs. The rains left various towns without power or water. By the night after the storm passed the island, more than 16,000 were without power, while almost 70,000 lacked potable water. Over 130 people were evacuated from low-lying areas to hurricane shelters. Two people were injured in Peñuelas, and three were injured in Nagüabo when the ceiling of a day care center collapsed, though no deaths occurred on the island. One airline canceled seventeen flights in and out of the island, and one cruise line was required to alter its path to both Dean and earlier due to Tropical Storm Chantal. Damage in Puerto Rico totaled to $7.7 million (2001 USD), of which $2.1 million (2001 USD) was from agricultural damage.<

Bahamas, Bermuda, and Canada

Shortly after Dean formed, the government of the

issued a

tropical storm warning Tropical cyclone warnings and watches are alerts issued by national weather forecasting bodies to coastal areas threatened by the imminent approach of a tropical cyclone of tropical storm or hurricane intensity. They are notices to the local pop ...

for the southeastern Bahamas and the

Turks and Caicos Islands The Turks and Caicos Islands (abbreviated TCI; and ) are a British Overseas Territory consisting of the larger Caicos Islands and smaller Turks Islands, two groups of tropical islands in the Lucayan Archipelago of the Atlantic Ocean and no ...

. When the storm weakened and ultimately dissipated, the warnings were canceled. The remnants of Dean produced unsettled conditions across

, including a wind gust of and light rainfall of . The passage of Dean resulted in the coldest day of August 2001 on the island. Dean produced wind gusts peaking at in

, along with rainfall up to in eastern Newfoundland. On land, wave heights reached , while a

buoy A buoy (; ) is a buoyancy, floating device that can have many purposes. It can be anchored (stationary) or allowed to drift with ocean currents. History The ultimate origin of buoys is unknown, but by 1295 a seaman's manual referred to navig ...

offshore reported a peak wave height of .

References

External links

NHC Tropical Cyclone Report for Tropical Storm Dean
{{DEFAULTSORT:Dean (2001) 2001 Atlantic hurricane season Atlantic tropical storms Hurricanes in Puerto Rico Hurricanes in Bermuda Hurricanes in Canada