Thursday, September 17, 2015

Tropical Depression Nine (2015)

Storm Active: September 16-19

On September 10, a tropical wave began to produce some shower activity as it moved off of the coast of Africa. Atmospheric conditions were initially unfavorable for any further development, but the system's environment improved on September 12, allowing it to organize. Meanwhile, it passed well south of the Cape Verde Islands, moving on a west-northwestward trajectory. On September 14, dry air interrupted the system's development and convection collapsed. The low associated with the system continued to persist and deepen, however, as upper-level winds remained low. After making a turn to the northwest, the system rebounded on September 16 and was classified Tropical Depression Nine.

Almost immediately after becoming a tropical cyclone, Nine entered an area of strong upper-level winds as it moved closer to an upper-level low to the northwest. Despite its convection being displaced well to the east of the center, Nine still managed a little strengthening early on September 17. In the midst of powerful wind shear associated with the strong El Nino event, the depression did little besides generate limited convection east of the center throughout that day and the next. By September 19, the system had become devoid of convection for the final time and the circulation became elongated along the southeast-northwest axis. Shortly afterward, the system lost tropical cyclone status. Its remnants continued generally northwestward until losing their identity.

Tropical Depression Nine was at its most organized immediately after formation (as shown above) while it remained in an environment that supported development.

The above image shows the track of Nine.

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