Sunday, August 13, 2017

Hurricane Gert (2017)

Storm Active: August 12-17

On August 2, a vigorous tropical wave left Africa and moved westward over the Atlantic Ocean. While environmental conditions seemed conducive for development, the system was unable to consolidate. Dry air interfered with the production of deep convection, and the associated circulation remained highly elongated. Competing vortices on the northeast and southwest sides vying for dominance cost the wave the chance to organize over the next several days. By August 7, conditions had become unfavorable due to the presence of an upper-level low to the northeast. Nevertheless, the system proceeded steadily west-northwestward, passing a bit north of the Lesser Antilles on August 10. Wind shear diminished and the wave encountered more humid air soon after, giving it another chance at development. Convection increased and the circulation became better defined over the next two days, and Tropical Depression Eight finally formed late on August 12.

The system was experiencing some wind shear out of the north, but conditions were otherwise supportive of intensification. August 13 saw the naming of Tropical Storm Gert when the system lay well east of the Florida coastline and was turning toward the north. The inner core structure improved considerably that night and into August 14. The first hints of an eye appeared that afternoon, and Gert was upgraded to a hurricane that night. The cyclone then began to feel the influence of a frontal system moving off of the U.S. east coast, and turned northeast on August 15, accelerating as it did so. Even as it gained latitude, Gert still took advantage of warm Gulf Stream waters to continue strengthening. A compact eye feature became apparent on both visible and satellite imagery by the morning of the 16th. That evening, the system reached its peak intensity as a category 2 hurricane with 105 mph winds and a minimum pressure of 967 mb near 40° N. Cooler waters and deteriorating atmospheric conditions finally caught up with Gert overnight and it weakened, beginning extratropical transition. The system became extratropical on the afternoon of August 17 as it sped east-northeastward over the open ocean.

The above satellite image shows Gert at peak intensity as a category 2 hurricane. Nova Scotia is visible at the top of the image.

A frontal boundary interacting with Gert steered it out to sea, minimizing land impacts.

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