Thursday, July 22, 2010

Tropical Storm Bonnie (2010)

Storm Active: July 22-24
On July 14, a tropical wave emerged off of Africa and moved westward. By July 17, the wave became associated with a broad upper-level low. However, very little storm activity accompanied the system at that time, as it moved westnorthwestward. On July 18, cloud cover increased in the system, but the circulation remained in the upper levels, prohibiting development. Over the next few days, the surface pressure began to drop and heavy rain from the system caused widespread flooding in Puerto Rico and Hispaniola. On July 22, a surface circulation appeared, and the system was upgraded to Tropical Depression Three, with 35 mph sustained winds and a pressure of 1008 mb just north of eastern Cuba. However, shower activity was primarily displaced to the north and east of the center due to wind shear.

Despite wind shear, a small intensification of the system during the evening of July 22 allowed the system to develop into Tropical Storm Bonnie, with 40 mph sustained winds. Due to an upper level ridge to the system's north, Bonnie accelerated to the westnorthwest during the morning of July 23, reaching a forward speed of 19 mph by 8:00 am EDT that morning. Soon after, the system slammed into Florida with 40 mph winds. Bonnie lost most of its convection before entering the Gulf, and was downgraded to a tropical depression. Despite a redevelopment of convection overnight, the surface pressures continued to rise and the system's center was stripped away by shear, leaving a exposed circulation. Bonnie continued struggling northwestward through the Gulf of Mexico during the morning of July 24, but it ultimately degenerated to a remnant low later that day. The low made landfall in Louisiana on July 25 as it dissipated. Damage was minimal, and one death was recorded in association with this system.

Bonnie after landfall in Florida.

Track of Bonnie.

Thursday, July 8, 2010

Tropical Depression Two (2010)

Storm Active: July 7-8
The tropical wave that eventually became Two formed over northeast South America within the ITCZ (Intertropical Convergence Zone). It slowly moved northwestward and as it moved into the western Caribbean, scattered thunderstorm activity began to be associated with it. However, this activity remained disorganized, and the system tracked over the Yucatan Peninsula on July 6. Although the system lost a lot of cloud cover over land, a low pressure center actually developed during this time, allowing the system to be more organized as it emerged into the Gulf of Mexico on July 7. However, the low pressure became elongated over the next few hours, and did not assume the perfect circular shape reminiscent of a healthy circulation. Nevertheless, convection continued to organize, and late that night the system was declared Tropical Depression Two with 35 mph winds and a minimum pressure of 1005 mb.

As had been the trend for a few days, the system lost much of its convection overnight, as it moved towards the Texas-Mexico border at 12 mph, but the circulation remained intact, and even strengthened a little. However, the system did not have enough time to reach tropical storm strength and made landfall in northern Mexico at 11:15 a.m. EST on July 8. The system quickly dissipated over land that evening. Overall, the main effect of Two was flooding, as it hit in an area which had already suffered from Hurricane Alex a few days eariler.

Two at landfall.

Track of Two.