Tuesday, August 28, 2012

Hurricane Kirk (2012)

Storm Active: August 28-September 2

On August 23, a tropical wave, already featuring a broad circulation, emerged off of Africa. Though the circulation deepened significantly over the next two days, convection remained scant, as the bane of the 2012 season, dry air, prevented further organization. The low moved northwest into less favorable environment the following day and wind shear took its toll on the system.

There was convection associated with the system as it moved over open waters, but it was displaced to the northwest. However, as shear abated slightly on August 27, the convection became nearer to, and even covered the center at times. On August 28, the system became more organized, and took a turn back to the west-northwest. By later that day, convection had persisted to such a degree that the cyclone was classified Tropical Depression Eleven.

Deep convection generally increased with the system overnight, giving it a more symmetrical appearance by the morning of August 29. Therefore, the cyclone was upgraded to Tropical Storm Kirk. Kirk increased in organization rapidly during that day, and, being a small cyclone, was able to quickly develop strong winds in its eyewall. On August 30, the structure of the system improved further as shear decreased, and a small eye formed, meriting the upgrade of Kirk to a hurricane that morning.

The cloud tops of the eyewall continued to cool that day, and the circulation became even more defined later that day, and Kirk rapidly strengthened through the night, bringing the cyclone to its peak intensity of 105 mph winds and a pressure of 970 mb early on August 31. By this time, the small cyclone was beginning to accelerate northward, as it came under the influence of mid-latitude winds.

However, conditions surrounding Kirk started to degrade later that day, as shear increased and the hurricane moved over cooler waters. Dry air finally invaded the system that afternoon, and the eye quickly vanished, as the compact circulation lost organization. Rapid weakening ensued.

By early September 1, Kirk had weakened to a tropical storm, and was accelerating towards the northeast. The system had already begun extratropical transition by later that day, but an area of deep convection near the center allowed Kirk to remain tropical through the morning of September 2, at this time still a moderate tropical storm. However, by the afternoon, the storm had lost any vestige of central convection, and was declared extratropical. It had been absorbed by a frontal boundary by the next day.

Kirk near peak intensity. Though a small system, Kirk featured a very symmetrical eye feature.

Track of Kirk.

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