Tropical Storm Nicholas (2003) - Meteorological History

Meteorological History

The origin of Tropical Storm Nicholas can be traced to a tropical wave that moved off the coast of Africa on October 9. It moved westward, and developed a broad area of low pressure along the wave on October 10. Convection organized around the low early on October 12 while located 800 miles (1300 km) southwest of the Cape Verde islands. As upper level winds became more favorable, the system became better organized, though the circulation center initially remained located to the west of the area of heavy showers. The surface circulation of the large circulation envelope moved towards a position near the western edge of the deepest convection, and it is estimated the system developed into Tropical Depression Nineteen late on October 13 while located 1,030 miles (1,660 km) west-southwest of the Cape Verde islands.

Located within an area of moderate southwesterly wind shear, the depression was slow to organize; early on October 14, a clear center was not depicted on Infrared satellite imagery. The depression moved to the west-northwest and gradually strengthened into Tropical Storm Nicholas late on October 14 while located 1,200 miles (1,930 km) east of the Windward Islands. On October 15, deep convection became much better organized, though the center of Nicholas remained displaced from the deepest of the shower activity. Despite the shear, the storm continued to strengthen as it moved to the west-northwest, a motion caused by a mid-level ridge to its north. On October 16, Nicholas transitioned from a sheared, unorganized system to a more organized system, as a result of banding features and improvement in its convective pattern due to lesser amounts of vertical shear and a healthier anticyclone over the storm. Nicholas continued to strengthen, and attained a peak intensity of 70 mph (110 km/h) on October 17 while located 875 miles (1,410 km) east of the Leeward Islands. Dvorak estimates suggested Nicholas potentially attained hurricane status, though microwave images of the storm showed a sheared system without any evidence of an eye feature.

Shortly after peaking in strength, Nicholas weakened due to increasing southwesterly wind shear, and the center of circulation briefly became exposed from the deep convection. In response to a break in the subtropical ridge, the storm turned to the north on October 18. Nicholas turned more to the west on October 20, and later on the winds in the storm decreased to minimal storm strength. Convection diminished greatly, though Nicholas unexpectedly re-strengthened as deep convection refired. After reaching winds of 50 mph (85 km/h), the storm again weakened due to increasing shear, and after turning to the northwest Nicholas degenerated into a tropical depression on October 23. Nicholas tracked northward in response to a break in the subtropical ridge, and on October 24, after degenerating to a remnant low pressure area, Nicholas lost what tropical characteristics it retained and transitioned into an extratropical cyclone. The remnant storm executed a large anticyclonic loop, resulting in a westward motion and a brief re-intensification into an extratropical storm on October 29. The storm continued to the west along a warm front associated with a non-tropical low to its southwest, and executed a second anticyclonic loop to the south. On October 30, convection increased over the low-level circulation of what was left to Nicholas, and the National Hurricane Center indicated a potential for tropical or subtropical development as it moved towards warmer waters. The system executed a small cyclonic loop, and on October 31 the system organized into a tropical low. It turned westward towards a non-tropical low, and on November 1 the remnants of Nicholas was absorbed by the low.

On November 1, convection increased in the complex system that absorbed the remnants of Nicholas, and the National Hurricane Center indicated the system could develop into a tropical or subtropical cyclone at any time. The low continued quickly westward, generating only sporadic convection, and crossed Florida on November 3. After entering the Gulf of Mexico, it turned to the west-northwest, and without organizing it made landfall in southeast Louisiana on November 4. It continued inland, and quickly weakened over Louisiana and Mississippi on November 5.