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Hurricane Rafael (17L) Completing Extra-Tropical Transitioning

46.0N 53.9W

October 18th, 2012 Category: Tropical Cyclones

Hurricane Rafael (17L) – October 18th, 2012

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Track of Hurricane Rafael (17L) - October 18th, 2012 © Univ. of Wisconsin

Track of TS 17L

A tropical wave exited the coast of Africa on October 5. On October 8, the NHC first monitored a tropical wave about halfway between Cape Verde and the coast of South America, which had a weak low pressure area and elongated convection. The thunderstorms gradually became more concentrated, and the system became better organized.

By October 10, the area was producing tropical storm-force winds in its northern periphery. Early on October 12, the system crossed into the eastern Caribbean Sea, passing near Saint Lucia. Later that day, a Hurricane Hunters flight confirmed a closed circulation, which prompted the NHC to initiate advisories on Tropical Storm Rafael (17L) about 125 mi (200 km) west-southwest of Dominica. At the time, the deepest convection was located to the east and southeast of the center, due to southwesterly wind shear from an upper-level low near Puerto Rico.

A weakness in the subtropical ridge allowed Rafael to track north-northwestward, and conditions were expected to favor further intensification. On the morning of October 13th, Rafael was observed to be moving north-westward followed by a slight left turn caused by a rebuilding mid–level ridge. On October 15, 2012, Rafael strengthened into a Category 1 hurricane with winds of 75 knots (85 mph, 140 km/h) as it was moving northeast. Rafael’s center was found to be relocated which has resulted in a track proceeding farther to the east. Rafael slowly intensified further, and reached its peak winds of 90 mph. Soon after, it began to weaken very slowly as it entered an environment of very strong vertical wind shear and cooler sea surface temperatures. During the afternoon hours of October 17, Rafael transitioned into a post-tropical cyclone, but remained powerful.

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