Hurricane Earl was a long-lived and powerful Cape Verde hurricane that impacted the Leeward Islands, Puerto Rico, the Bahamas, the East Coast of the United States, and Atlantic Canada. The fifth named storm of the season, Earl originated from a tropical wave to west of the Cape Verde Islands on August 25, 2010. Tracking nearly due west, the system attained tropical storm intensity within hours of genesis. After maintaining winds of for nearly two days, Earl began to strengthen as it neared the Lesser Antilles. The storm intensified into a hurricane on August 29 and later a major hurricane on August 30 as it brushed the Leeward Islands. A temporary weakening trend took place as Earl moved northwestward, contributed to moderate southwesterly wind shear, but intensification later resumed by September 1. Once reorganized, Earl reached its peak winds of . Executing a gradual curve to the northeast, the hurricane slowly weakened over decreasing sea surface temperatures; the storm's center passed roughly east of Cape Hatteras, North Carolina on September 3. Accelerating northeastward, the system briefly weakened to a tropical storm before reattaining hurricane strength as it made landfall near Western Head, Nova Scotia. After traversing the peninsula, the hurricane became extratropical and was later absorbed by a larger low pressure area on September 6, while located north of Newfoundland.
In the Lesser Antilles, the storm brought strong winds, damaging houses and toppling trees, signs, and power lines, resulting in hundreds of thousands of electrical outages. Heavy rainfall led to flooding, inundating streets and leaving waist-deep water on some islands. One death occurred in Antigua and Barbuda when a person was electrocuted while attempting to restore power. The region was inflicted with at least $40.8 million (2010 USD) in damage. Along the coast of the Eastern United States, tropical storm-force winds affected portions of North Carolina and Massachusetts; however, little damage resulted, totaling about $3.8 million in the Outer Banks. Six fatalities were confirmed in the United States as a result of rip currents and rough seas; three in Florida, two in New Jersey and one in Massachusetts. In Nova Scotia, Canada, where Earl made landfall as a Category 1 hurricane, one person drowned and hundreds of thousands of people lost power for days.
Meteorological history
Earl was detected from an vigorous tropical wave that emerged on early August 22. The wave formed in a well-organized area of low pressure and moved into the Atlantic Ocean as early August 23. After moving off the west coast of Africa, a surface low started to develop near the area of thunderstorms. The surface low was able to organize the area of thunderstorms, allowing deep convection to occur near it. Because of the area's increasing thunderstorm organization, the National Hurricane Center (NHC) indicated on August 24 that the system had a 90% chance of becoming a tropical depression within the next 48 hours. 24 hours later, the NHC classified the system as Tropical Depression Seven at around 1500 UTC on August 25, while it was located about west of the southernmost Cape Verde Islands. Six hours later, at about 2100 UTC, the system's maximum sustained winds were estimated to be . Accordingly, the depression was declared to have become the fifth tropical storm of the season, and received the name Earl.
Earl was forecast to head westward while gradually strengthening under the influence of low wind shear and warm ocean temperatures. However, dry air caught in Earl's circulation precluded additional intensification, causing the storm to maintain maximum sustained winds for 36 hours. On August 29, the storm resumed gradual intensification, even though wind shear increased due to the outflow from nearby Hurricane Danielle. The wind shear caused Earl's low level center of circulation to become exposed, limiting Earl's intensification to maximum sustained winds during the following 12 hours. As the storm neared the Leeward Islands, convection increased around Earl and defined banding features formed. Around 1230 UTC, Earl strengthened into a hurricane roughly east of the northern Leeward Islands. Rapid intensification ensued throughout the day as a wide eye became apparent in radar imagery from Guadeloupe.
Hurricane Earl's outflow steadily improved through August 30 and sustained winds rose above , making Earl a Category 2 storm. Around 1200 UTC, the center of Earl passed roughly east-northeast of St. Martin with sustained winds of . Several hours later, the storm further intensified into a major hurricane. That afternoon, Earl became a Category 4 hurricane, attaining winds of before leveling out in intensity. A northwestward track began to become apparent by this time as the system neared the southwestern periphery of a subtropical ridge over the Atlantic Ocean. Early on August 31, an eyewall replacement cycle, a process in which a storm's eye dissipates and is replaced by a larger one, began to take place. Despite increasing wind shear, the system maintained its intensity through September 1, when it briefly weakened to a Category 3 system. Gradual strengthening took place throughout the day as the eye became better defined and convection deepened around the center. Additionally, the storm began to turn northward in response to the ridge over the Atlantic and a strong trough over the Great Lakes. Hurricane Earl later attained its peak intensity during the morning of September 2 with winds of and a barometric pressure of 928 mbar (hPa; 27.40 inHg).
During the afternoon of September 2, Earl finally succumbed to the effects of increased shear and cooler water temperatures. Embedded within the mid-latitude westerlies, a gradual northeasterly turn was expected over the following day, preventing Earl from making landfall along the East Coast of the United States. Around 0600 UTC the next morning, the storm made its closest approach to the United States, passing roughly east of Cape Hatteras, North Carolina with winds of . Further weakening took place throughout the day as convection weakened and the eye dissipated. Earl was downgraded to a tropical storm that evening; however, the central pressure remained at an unusually low 958 mbar (hPa; 28.29 inHg). At the same time, the storm made its closet approach to Massachusetts, passing roughly southeast of Nantucket. Continuing northeastward, Earl neared the Canadian Maritimes, re-strengthening slightly and regaining hurricane intensity as it approached the region. The storm made landfall in Queens County near Western Head, Nova Scotia around 1400 UTC on September 4, as a Category 1 hurricane with sustained winds of . After crossing Prince Edward Island, the storm entered the Gulf of Saint Lawrence. There, the system finally transitioned into a post-tropical storm as its windfield became asymmetric and the eastern portion of the circulation became associated with a frontal system. During the afternoon of September 5, the remnants of Earl were absorbed by a mid-latitude low roughly north-northeast of St. Anthony, Newfoundland.
Research
As Hurricane Earl tracked along the East Coast of the United States, a new program, the Genesis and Rapid Intensification Processes (GRIP), was launched. A former military aircraft, a WB-57 able to reach an altitude of , carrying 15 new instruments was flown into the storm. Additionally, routine Hurricane Hunter missions were flown into Earl, a DC-8 and the first use of an unmanned research drone. Combined, these missions made Hurricane Earl the most studied tropical cyclone in history, according to Tim Miller, the lead scientist in GRIP. The outcome of the extensive research allowed for substantially improved forecasts during the latter part of Earl's existence. As compared to a similar storm, Hurricane Floyd in 1999, warnings covered roughly less coastline, saving residents and businesses roughly $1 billion in evacuation losses.
In Anegada, a geological study, focusing on beach deposits from two significant wash-out events between 1650 and 1800, was given additional research material by the storm. Deposits left behind by the major hurricane were substantially less than the time period being studied. This led researchers to determine that a tsunami was likely the cause, rather than a hurricane. This also allowed for a connection to the 1755 Lisbon earthquake to be confirmed.
Preparations
Caribbean On August 27, France issued a tropical storm watch for the French side of Saint Martin and Saint Barthélemy. The next day, Antigua and Barbuda and the Netherlands Antilles issued tropical storm watches for Antigua, Barbuda, Montserrat, St Kitts and Nevis and Anguilla and for Sint Maarten, Saba and Sint Eustatius. Hours later, most of the watches were upgraded to tropical storm warnings; a tropical storm watch was also issued for the United States Virgin Islands. By August 28, hurricane warnings were in place for the areas between Anguilla and Montserrat; hurricane watches were declared for the U.S. and British Virgin Islands as well as Puerto Rico. As Earl moved closer to the northeastern Caribbean, warnings were extended westward through the Virgin Islands.
Throughout the Leeward Islands, heavy rains produced by the storm flooded low-lying areas. During the late morning of August 30, some of the hurricane warnings were replaced by tropical storm warnings; the Turks and Caicos islands were also placed under a tropical storm watch. Several hours later, all warnings for Antigua and Barbuda were discontinued. That afternoon, all hurricane advisories were discontinued as Earl moved away from the Caribbean islands. By August 31, the remaining advisories for the Caribbean were discontinued; the Turks and Caicos were also placed under a tropical storm warning. Early on September 1, the Government of the Bahamas discontinued all advisories in relation to Hurricane Earl.
Beginning on August 28, local governments placed emergency agencies on standby for possible damage from Hurricane Earl. Press releases were made to the public in order to give sufficient time for preparations. The following day, emergency shelters were opened on Anguilla, Antigua, Barbuda, Montserrat, St. Kitts, Nevis and the Virgin Islands. On St. Kitts and Nevis, the Robert L. Bradshaw International Airport and Vance W. Amory International Airport were shut down and scheduled to re-open the following day. All emergency services were placed on standby on Anguilla, Antigua and Barbuda. Prior to Earl's arrival in the Leeward Islands, the Leeward Islands Air Transport canceled 42 flights to and from the region. The V. C. Bird International Airport on Antigua was closed on August 29 and set to reopen after the storm passes. Although not in the direct path of Hurricane Earl, officials in the Dominican Republic prompted evacuations of coastal towns and canceled flights across the country.
United States