Tropical Storm Colin was a tropical cyclone that brought squally weather to Bermuda and caused extensive rip currents across the East Coast of the United States in August2010. The fourth tropical cyclone and third named storm of the 2010 Atlantic hurricane season, Colin developed as a tropical depression from a low-pressure area in the central Atlantic on August2. After forming, the storm initially strengthened gradually, attaining tropical storm status early on August3. However, due to its acceleration to the west-northwest, Colin was unable to maintain a closed circulation and subsequently degenerated into a trough later that day. The National Hurricane Center noted the possibility of regeneration over subsequent days, and by August5, Colin had once again become a tropical cyclone. Despite moderate wind shear impacting the system, Colin reached a peak intensity of 60mph (97km/h) on August5. However, vertical wind shear prevented further intensification and eventually weakened the storm. By early on August8, Colin had weakened to a tropical depression, and dissipated near Bermuda shortly after. Though it remained well offshore, Colin produced rough seas along the East Coast of the United States. At least 205ocean rescues were made. In Bermuda, effects were generally minimal. Less than 1 inch (25mm) of rain fell and winds remained below tropical storm force.
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Tropical Storm Colin
Colin shortly after regenerating into a tropical storm on August5
The origins of Tropical Storm Colin can be traced back to an elongated tropical wave that moved westward from Nigeria to Senegal on July28. A nearly stationary trough separated from the wave as it continued westward. A larger tropical wave emerged off the west coast of Africa a few days later. A broad area of low pressure resulted from the consolidation of the two waves on August1, when it was situated about 750mi (1,210km) west-southwest of the Cape Verde Islands. Over the course of the next 24 hours, shower and thunderstorm activity became increasingly consolidated with the low, but the system lacked a well-defined circulation to be considered a tropical cyclone at the time. However, on the next day, an Advanced Scatterometer (ASCAT) pass revealed that the circulation center had become sufficiently defined, and the National Hurricane Center (NHC) initiated advisories on Tropical Depression Four at 1200UTC on August2.[1] Further organization occurred as the depression moved around the southern periphery of a strong subtropical ridge. Thunderstorm activity became increasingly well defined, and it is estimated that the depression became Tropical Storm Colin at 0600UTC on August3 while centered 840mi (1,350km) east of the Lesser Antilles.[1]
Early on August3, Colin's forward motion increased, and the cyclone was unable to maintain a closed circulation. The tropical storm degenerated into a trough at 1800UTC, although tropical storm-force winds persisted.[1] As the remnants passed north of the northern Leeward Islands, a reconnaissance aircraft investigated the system on August4, but no closed circulation was found. As the remnants approached a weakness in the subtropical ridge across the western Atlantic on August5, its forward speed gradually slowed as well. A combination of microwave and satellite imagery during the morning hours of August5 revealed the reformation of a closed low, and Colin's remnants regained tropical storm status at this time while located 280mi (450km) north-northeast of San Juan, Puerto Rico.[1]
Despite relatively unfavorable vertical wind shear impacting Colin, deep thunderstorm activity developed atop its center of circulation. Data from a reconnaissance aircraft during the afternoon hours of August5 revealed that the system reached a peak intensity with winds of 60mph (97km/h) and a minimum barometric pressure of 1,005mbar (29.7inHg). A few computer models, namely the Geophysical Fluid Dynamics Laboratory (GFDL) and Hurricane Weather Research and Forecasting model (HWRF), predicted that Colin would briefly attain hurricane status.
[2] However, the surrounding moderate vertical wind shear prevented this. While turning towards the north on August6, the cyclone entered an area increasingly unfavorable wind shear and cooler sea surface temperatures, subsequently prompting the NHC to downgrade Colin to a tropical depression by 0000UTC on August8. Further weakening occurred over the next few hours as the cyclone's center of circulation became elongated, and Colin once again degenerated into a trough of low pressure at 1200UTC while located approximately 100mi (160km) southwest of Bermuda. The remnant trough persisted until early on August9, at which time it was situated 150mi (240km) northwest of the island.[1]
Preparations and impact
Following Colin's regeneration into a tropical cyclone on August5, the Government of Bermuda simultaneously issued a tropical storm warning for the island.[3] Along south-facing beaches, Colin was expected to produce a storm surge between 2 and 3ft (0.61 and 0.91m), possibly reaching as high as 5ft (1.5m). Significant rainfall was also anticipated, with totals averaging 4 to 6in (100 to 150mm).[4] These values were later decreased after Colin weakened on August6, with only a minimal storm surge forecast and rainfall roughly 1in (25mm) less than previously stated.[5] By August7, all beaches were closed across the island due to rough seas and dangerous rip currents.[6] The Royal Caribbean cruise ship, MS Explorer of the Seas, arrived in Bermuda that same day and was scheduled to set sail again on August8; however, due to the threat of Colin, the vessel was forced leave later in the day instead of staying overnight.[7] On August8, the tropical storm warning in place for Bermuda was downgraded to a watch as Colin weakened to a tropical depression;[8] it was discontinued hours later as the storm quickly dissipated.[9]
Due to Colin's weakening to a tropical depression prior to its closest pass to Bermuda, its effects were significantly less than initially anticipated. Winds from the storm reached 31mph (50km/h), with gusts to 37mph (60km/h). Rainfall was limited to isolated showers and thunderstorms; the Bermuda International Airport measured 0.16in (4.1mm) of rain in relation to Colin. Throughout the island, there were no reports of damage.[10]
Although situated several hundred miles off the coast of the East Coast of the United States, the outer effects of Colin were expected to create dangerous rip currents along the North and South Carolina coastlines,[11] as well as waves as high as 3 to 4ft (0.91 to 1.22m).[12] On August7, a 51-year-old man drowned off the coast of Ocracoke, North Carolina after being caught in a rip current. Shortly after his death, officials issued rip current and undertow threats for the region.[13] Between August7 and 9, at least 205 ocean rescues were made along the North Carolina coastline due to rough seas produced by Colin.[14]
Beven, Jack L. (August 5, 2010). Tropical Storm Colin Advisory 7 (Report). National Hurricane Center. Archived from the original on January 2, 2014. Retrieved January 15, 2012.
Stewart, Stacy R. (August 6, 2010). Tropical Storm Colin Advisory 9 (Report). National Hurricane Center. Archived from the original on January 3, 2014. Retrieved August 7, 2010.
Beven, Jack L. (August 6, 2010). Tropical Storm Colin Advisory 12 (Report). National Hurricane Center. Archived from the original on January 3, 2014. Retrieved August 7, 2010.
Brown, Daniel P. (August 8, 2010). Tropical Storm Colin Advisory 19 (Report). National Hurricane Center. Archived from the original on January 3, 2014. Retrieved August 9, 2010.
Brown, Daniel P. (August 8, 2010). Tropical Storm Colin Advisory 20 (Report). National Hurricane Center. Archived from the original on January 2, 2014. Retrieved August 9, 2010.