Monday, November 9, 2015

Hurricane Kate (2015)

Storm Active: November 8-12

Kate originated from a trough of low pressure that moved across the tropical Atlantic during the first week of November. The system moved west-northwest across the northeastern Caribbean, passing near Puerto Rico on November 7. Early on November 8, a low pressure center appeared on the south end of the trough just north of Hispaniola and thunderstorm activity became better organized. The low became well-defined enough to be classified Tropical Depression Twelve late that evening. The next morning, the depression was upgraded to Tropical Storm Kate as deep convection increased near the center. At that time, the storm was moving northeast over the Bahamas, but its small size limited rainfall totals.

After the center briefly became exposed on the south side of the convective canopy, organization began to improve, with banding features appearing. Kate strengthened as it moved northward away from the Bahamas during the afternoon. The system meanwhile began to accelerate toward the north and eventually northeast on November 10. Despite diminishing sea surface temperatures, the storm continued to intensify through November 11, when it strengthened into a hurricane. Hurricane Kate reached its peak intensity of 75 mph winds and a pressure of 985 mb that morning, at which time it was already north of Bermuda, speeding toward the northeast at 40 mph. The cyclone was already showing signs of extratropical transition that afternoon as it moved over the cold northern Atlantic. By November 12, the circulation had become quite elongated and the remaining convection warm and asymmetric, so Kate was declared extratropical. The still powerful system continued north and east across the Atlantic before merging with another low a few days later.

The above image shows Kate at peak strength moving rapidly out to sea on November 11. The cyclone was already exhibiting some asymmetry and diminished central convection, two signs of extratropical transition.

Hurricane Kate affected the Bahamas as a tropical storm before recurving away from the United States coastline.