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Friday, October 10, 2014

Hurricane Fay (2014)

Storm Active: October 10-13

Around October 8, persistent shower and thunderstorm activity appeared in conjunction with a low pressure system located northeast of the Windward Islands. As the low moved west-northwestward over the following day, environmental conditions improved. On October 9, the trough associated with the circulation center became visibly curved with the development of a semicircular rain band about the low's north and east sides. Meanwhile, surface pressures continued to fall, and the circulation became much better defined by the morning of October 10. At this time, the system was organized enough to be designated Subtropical Depression Seven.

Through the evening, an area of deeper convection within the rain band developed northwest of the center. Since aircraft reconnaissance data indicated that higher winds were occurring in this area, the intensity of the system increased significantly, and Seven was upgraded to Subtropical Storm Fay. By the morning of October 11, Fay had come to the western edge of a subtropical ridge and had assumed a northward motion toward Bermuda. In addition, the area of deep convection moved close enough to the center and became symmetrical enough that Fay transitioned to a tropical storm that same morning.

Later that day, despite moderate shear aloft, the convective canopy covered Fay's center for the first time. The central pressure continued to drop meanwhile, and Fay intensified to near-hurricane strength. By this time, conditions were rapidly deteriorating in Bermuda. Early in the morning on October 12, the center of the cyclone passed almost directly over Bermuda, bringing winds gusting to hurricane strength, 3-5 inches of rain, and large sea swells. The system continued to curve to the east and accelerate as it passed the island that day. During the afternoon, Fay briefly developed a small eye, and became more symmetrical as shear temporarily lessened. As a result, the cyclone was upgraded to a minimal hurricane and reached its peak intensity of 75 mph winds and a pressure of 986 mb.

During the evening and overnight, however, wind shear increased substantially, quickly weakening the system back below hurricane strength and displacing its convection to the northeast of the center. On October 13, a frontal boundary moving off of the United States was steering Fay nearly due east, and the interactions between the two systems contributed to the tropical storm's dissipation later that day. The remnant vortex of Fay became embedded in the same front by the afternoon.



The above image shows Fay passing near Bermuda on October 12.



Fay's track includes square points, indicating a time at which the cyclone was subtropical.

Sources: http://upload.wikimedia.org/wikipedia/commons/a/a9/Fay_Oct_12_2014_1455Z.jpg, http://upload.wikimedia.org/wikipedia/commons/8/83/Fay_2014_track.png

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