Tuesday, September 3, 2019

Tropical Storm Gabrielle (2019)

Storm Active: September 3-10

As August came to an end, another tropical wave moved over the Atlantic waters from its origin in west Africa. A circulation quickly developed over the next few days, but thunderstorm activity remained rather scattered. The system tracked west-northwest and more intense convection appeared on September 3. It was therefore designated Tropical Depression Eight. Due to a weakness in the Bermuda high about halfway Bermuda and the Azores, the cyclone was able to steadily gain latitude on a northwest heading over the next several days. The waters under the system were hovering right around the benchmark 80 ° F (26.6 ° C) typically needed for tropical development and the atmospheric conditions were only marginally favorable. Despite this, Seven strengthened steadily into Tropical Storm Gabrielle on September 4.

Southerly shear helped to give the storm a "comma" shape, with convection nearest the center on the northwest side, arcing off to the northeast. It lost some convection that day as shear increased a bit more, making conditions actually fairly hostile. Nevertheless, Gabrielle maintained its intensity into September 5. During the day though, shear eliminated any remaining cloud cover from near the system. Devoid of convection for 24 hours, the system was briefly declared extratropical during the morning of September 6. However, the storm redeveloped just 6 hours later as thunderstorm activity reappeared. Meanwhile, the storm continued northwest, but accelerated a little. Shear from the south decreased the next day, only to be replaced by strong shear out of the northeast! In fact, this drove a reformation of the center of the circulation farther west that morning.

Conditions finally improved a bit for Gabrielle later that day, and it strengthened some overnight. As it gained latitude, the system moved around the edge of the high pressure to its east and began to recurve northeastward. Meanwhile, it reached its peak intensity of 65 mph sustained winds and a pressure of 995 mb. By the morning of September 9, Gabrielle was speeding off toward the northeast. It weakened gradually in response to increasing wind shear and cooler ocean temperatures that day. Extratropical transition began that day and completed during the morning of September 10. The remnants of Gabrielle continued northeast until dissipation within a couple days.



Gabrielle was a relatively small cyclone, beset by shear most of its life.



Gabrielle did not affect any landmasses as a tropical cyclone.

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