Monday, October 24, 2011

Hurricane Rina (2011)

Storm Active: October 23-28

During the day of October 18, a cold front swept across the Gulf coast. Heading unusually far south, the front continued to moved over the Gulf, crossing the Yucatan Peninsula during the afternoon of October 19. Simultaneously, a tropical wave, moving through the Caribbean, degenerated into a trough, though it still produced showers and thunderstorms. On October 20, these systems merged off of the coast of Nicaragua and a low pressure system formed.

Over the next day, the low drifted south and then west, all the while increasing in organization. Thunderstorm activity became concentrated just off the coast of Nicaragua during the evening of October 21, However southwesterly wind shear displaced thunderstorm to the west of the low pressure center, causing some heavy rainfall in Central America the following day. On October 23, now moving northward off of the coast of Honduras, the low experienced a reformation, with the new center within the southern edge of the convection. That afternoon, sufficient organization had been attained to classify the system as Tropical Depression Eighteen.

An increase in the symmetry of Eighteen later that night merited an upgrade to Tropical Storm Rina. A series of increases in sturutal organization followed early on October 24, with the outflow imporving in all quadrants. Despite this, the eyewall itself did not undergo any major changes until the early afternoon, at which time a contraction caused a well-defined eyewall, as well as a radiating band feature, to form. Rina was therefore upgraded directly from 45 mph to a hurricane.

Shortly afterward, Rina turned to the west and decreased in speed due to the influence of a ridge over the Gulf of Mexico. Meanwhile, Rina's internal structure continued to improve, and an eye appeared on visible, but not infrared images. Therefore, early on October 25, the cyclone underwent another burst of strengthening and became a Category 2 hurricane. Further fluctuations in the strength of the eyewall pushed Rina to its peak intensity that night, achieving winds of 110 mph and a pressure of 966 mb.

The hurricane maintained this intensity through the morning, but a tongue of dry air invaded from the north. This, coupled with increasing wind shear caused rapid deteriorated of the circulation, reducing Rina's intensity to that of a Category 1 hurricane. As the cyclone began to turn north, the area of deep convection associated with the system shrunk. By October 27, interaction with the Yucatan Peninsula to the west and the exposure of the center of circulation weakened Rina to a tropical storm. Later that day, Rina made landfall near Cancun, causing heavy rainfall and a small area of tropical storm force winds.

By the morning of October 28, the system emerged into the Yucatan Channel and weakened into a tropical depression. All convection had been displaced to the north by this time, and Rina degenerated into a remnant low that afternoon. It was absorbed by a front the next day. Due to its rapid degeneration, the cyclone caused only minimal damage in Central America.

Hurricane Rina at peak intensity, with an eye feature apparent on visible imagery.

Track of Rina.