A tropical wave entered the Atlantic ocean around September 12 and moved slowly westward over the next several days. It produced a significant amount of thunderstorm activity but remained quite disorganized. The system was eventually designated Tropical Depression Seven on September 17. At the time, it was a little past halfway from Africa to the Windward Islands. Despite achieving tropical depression status, the cyclone was still a mess, with almost all convection displaced east of the center. Furthermore, the center itself was a warring group of vorticies rotating around one another. Later that day, the center reformed further north, coaxed poleward by an upper-level low over the subtropics. The storm's winds also increased enough that it was upgraded to Tropical Storm Gabrielle.
Gabrielle evened out to a more steady west-northwest heading on the 18th and consolidated its circulation, but struggled to produce thunderstorm activity. For most of the day, it was little more than a naked swirl. That evening, it began to put up a better fight against westerly wind shear and storm activity blossomed in the eastern semicircle. Nevertheless, atmospheric conditions remained hostile through the next day. It was only on the 20th that shear lessened and Gabrielle was able to start intensifying again. The storm spent the next few days curving around the western edge of the subtropical ridge, first turning toward the north and toward the east. This path kept it east of Bermuda, too far to cause any direct impacts to the island. This was fortunate, because Gabrielle strengthened significantly.
On the 21st, it was upgraded to a hurricane. Shortly after that, the cyclone's satellite presentation improved markedly. An eye quickly cleared out and became more symmetric. Gabrielle vaulted to major hurricane strength by the morning of September 22. That afternoon it reached its peak intensity as a category 4 hurricane, with maximum winds of 140 mph and a central pressure of 948 mb. The storm accelerated toward the east-northeast and encountered gradually increasing wind shear as well as decreasing ocean heat content. This began a decaying trend, though it remained a significant hurricane.
Gabrielle began to lose tropical characteristics late on September 24 as the central core collapsed and it weakened to a category 1 hurricane. By this time, the storm was speeding eastward toward the central Azores. During the afternoon of September 25, a few hours before arriving at the islands, Gabrielle transitioned to a post-tropical cyclone. This did not prevent the cyclone from bringing strong winds, storm surge, and brief heavy rains to the Azores; during the storm's passage, hurricane-force gusts were recorded at sea level as well as hurricane-force sustained winds at higher elevations. A fully extratropical ex-Gabrielle exited the island chain toward the east by the next morning. Its remnants passed near the coast of Portugal before dissipating days later.
The image above shows Gabrielle as a category 4 hurricane on September 22.
Gabrielle did not directly impact any land areas as a tropical cyclone, but did make a direct hit on the Azores shortly after losing tropical characteristics.
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