Monday, June 17, 2013

Tropical Storm Barry (2013)

Storm Active: June 17-20

A tropical wave located off the eastern coast of Nicaragua began to show signs of organization on June 15. On June 16, a swirling of clouds became evident on satellite imagery, though a surface circulation had not yet formed and, in any case, the proximity of the developing circulation to central America limited thunderstorm activity.

However, the disturbance emerged into the northwest Caribbean on June 17, and late that morning, a low-level circulation appeared and the system was upgraded to Tropical Depression Two only 60 miles east of the coast of Belize. Later that day, the depression made landfall in Belize at an intensity of 35 mph winds and a pressure of 1008 mb, bringing heavy rainfall to the region.

The depression weakened over land, and lost definition, but the system continued to move west-northwest, and the northern half of the circulation regained convection as the northwestern portion emerged into the Bay of Campeche early on June 18. A ridge situated over the northern Gulf of Mexico weakened slightly that day, allowing the cyclone to shift north slightly in its path. As a result, the center entered the Bay of Campeche during the afternoon of that day, and thunderstorm activity soon recovered near the center.

Though moderate wind shear still affected the depression out of the southwest, the shear began to weaken during the morning of June 19, as the system made a turn westward toward the Mexican coast. This allowed the thunderstorm activity to increase markedly, and the depression was upgraded to Tropical Storm Barry that afternoon. The system continued to gain organization through the early morning of June 20, reaching its peak intensity of 45 mph winds and a pressure of 1003 mb before making its final landfall in Mexico later that morning.

The system quickly weakened over land, becoming a tropical depression that evening, and degenerating into a remnant low late that night. Barry main effect was heavy rainfall; the tropical storm dumped several inches of rain over a large swath of southern Mexico, with localized totals-especially in mountainous regions-exceeding 5 inches.

Tropical Storm Barry achieved its peak intensity as a weak tropical storm shortly before its second landfall in Mexico.

A combination of a slow forward speed and extensive moisture from the Bay of Campeche made Barry a significant flooding threat near the end of its life.

Thursday, June 6, 2013

Tropical Storm Andrea (2013)

Storm Active: June 5-7

On June 2, scattered shower activity associated with a trough situated near the eastern coast of the Yucatan Peninsula begin to organize. The system moved north-northwest, and despite only marginally favorable conditions, partially stemming from frontal boundaries moving through the north Gulf of Mexico, developed further. Surface pressures declined near the center of the disturbance during the day of June 4, but the circulation remained broad, and all convection was displaced to the east of the forming center by wind shear in the western Gulf. On June 5, conditions became briefly favorable for formation as the disturbance moved northward, and an aircraft investigating the system found that a well-defined center had formed. The system was therefore named Tropical Storm Andrea, the first tropical cyclone of the 2013 season.

By the early hours of June 6, Andrea was already accelerating north-northeast in the wake of a trough lifting out of the southeast United States. The structure of the cyclone already exhibited some extratropical properties, as its convection was still displaced generally to the north of the center, and a band southeast of the center, reminiscent of a frontal boundary, was forming. Despite this, the circulation deepened and Andrea underwent modest strengthening during that day.

Torrential rains had already begun over Florida and parts of South Carolina that afternoon as the northern bands of Andrea's circulation interacted with a frontal system moving towards the east coast. The system made landfall in northwestern Florida at its peak intensity of 65 mph winds and a pressure of 993 mb at 5:45 pm that evening. The system accelerated considerably and weakened quickly over land overnight as the circulation broadened and dry air invaded the center of circulation early on June 7. By that afternoon, the cyclone was declared post-tropical.

As the cyclone moved northeastward, it caused significant rainfall across the mid-Atlantic and towards New England as the center of circulation stayed near the coastline. The remnants of Andrea dumped a few inches of rain across a large swath of this region in conjunction with the frontal system steering it. By the afternoon of June 8, the cyclone had lifted out of New England.

Tropical Storm Andrea reached peak intensity shortly before making landfall in Florida.

Andrea tracked up the U.S. east coast, largely as a post-tropical cyclone, and brought heavy rainfall to many areas.