On September 15, a tropical wave entered the Atlantic ocean. Some disorganized thunderstorm activity developed near the northern end of the tropical wave over the next couple of days. A weakness in the Azores high pressure allowed the disturbance to lift northward, though this brought it into generally less favorable conditions for cyclone development. Around September 19, a weak low formed in association with the system; rather unexpectedly, it became Tropical Depression Eight the next day. Finding a window of light wind shear and an unstable atmosphere, it began to intensify and became Tropical Storm Gaston by the evening.
Gaston was not completely tropical; it derived some of its energy from baroclinic processes, which allowed it to intensify in a rather unfriendly environment. On the 21st, it became a strong tropical storm. It had moved north-northeast since formation, but turned more toward the east the next day, following a clockwise path around the northern edge of the Azores high. Speaking of the Azores, the system was approaching the westernmost islands by that evening. Gaston was a relatively small storm and was beginning to lose its inner core by that point, but it still brought scattered heavy rains to the Azores beginning late on September 22.
The center in fact veered south and moved very close to the islands the next day. Gaston even underwent an bit of unexpected strengthening and reached its peak intensity of 65 mph winds and a central pressure of 995 mb that afternoon. Soon after, upper level winds and more stable air quelled convective activity and caused the system to weaken. The storm continued its clockwise path, turning back toward the west on September 24. Though a few bursts of thunderstorms halted weakening temporarily, the general degradation of Gaston continued until it became post-tropical on September 25.
The above image shows Gaston approaching the Azores on September 23.
Gaston took a meandering track across the subtropical Atlantic away from any land besides the western islands of the Azores.
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