Sunday, September 27, 2009

Tropical Depression Eight (2009)

Storm Active: September 25-26

A tropical wave moved off of Africa on August 23, and began to develop disorganized showers and thunderstorms as it moved to the west-north-west at about 15 mph. On September 24, the Cape Verde Islands received scattered showers and thunderstorms as it passed to the south of the region. On September 25, the wave began to organize west of the Cape Verde Islands, despite being in an area only marginally favorable for tropical cyclone formation and started to develop a center of circulation. The system was declared Tropical Depression Eight at 5 p.m. on September 25 already at its peak intensity of 35 mph winds and a pressure of 1008 millibars. Over the next day, the depression moved northwest into cooler waters and became less organized. Then, exactly a day after formation, Eight lost its center of circulation and dissipated. The tropical wave continued to produce shower activity as it moved northwest and was monitored for regeneration, but no new low formed, and the possibility for reformation was gone by September 27.

The tropical wave destined to become Tropical Depression Eight organizing in the East Atlantic.

Track of Eight

Saturday, September 12, 2009

Hurricane Fred (2009)

Storm Active: September 7-12

On September 6, a strong, organized, tropical wave associated with an area of low pressure moved off of Africa and quickly developed into Tropical Depression Seven the next day. The depression passed south of the Cape Verde Islands and intensified into Tropical Storm Fred on September 7. Fred's center became well-defined, and the system strengthened through the next day, becoming Hurricane Fred on September 8 with 75 mph winds and a pressure of 987 millibars. Hurricane Fred jumped to Category 3 intensity in just 12 hours and reached its peak intensity of 120 mph winds and a pressure of 958 millibars on September 9. At his time, Fred had a distinct eye feature, and it became the most southeasterly major hurricane ever to form in the Atlantic Ocean. Fred curved to the north, due to a ridge to its west, and its southeast side weakened. As a result, strong wind sheer ripped at the system from that direction, causing Fred to weaken, becoming a tropical storm on September 11. Convection began to separate from the center to the north, and Fred became nearly stationary, drifting east, then south, and weakening all the time and making a tight loop in the Eastern Atlantic. By mid-afternoon on September 12, Fred was a minimal tropical storm, with almost no convection. It was then downgraded to a remnant low that night, and moved west. The low continued to produce shower activity, but dissipated on September 16. However, a new low formed in association with Fred's remnants 500 miles south of Bermuda and the area was monitored once again. The low continued to drift west, and finally dissipated, becoming part of a frontal boundary, on September 20.

Hurricane Fred at Category 3 intensity in the far east Atlantic.

Track of Fred. Note that the triangles signifying Fred's remnant low continued much farther west before dissipating.

Wednesday, September 2, 2009

Tropical Storm Erika (2009)

Storm Active: September 1-3

On August 26, a tropical wave moving off of Africa became associated with a broad area of low pressure south of the Cape Verde Islands, producing shower and thunderstorm activity. However, the cloud cover and organization diminished over the next few days as the system moved west. By August 31, though, the low had regenerated into an organized ball of convection. The system was organized enough to be a tropical storm and had tropical storm force winds, but i still wasn't classified. This was because it lacked a center of circulation. The low was an elongated oval, widest north to south, and a center could have formed anywhere along the oval. During the afternoon of September 1, a center began to for, evident on visible imagery as a point just east of the cloud cover associated with with the system. Therefore, like the previous storm Danny, the system skipped tropical depression status and was upgraded directly to Tropical Storm Erika, with 50 mph winds and a pressure of 1007 millibars. Later that night, the pressure dropped to 1004 millibars and the winds increased to 60 mph, but Erika took a southerly turn and weakened the next morning. By mid-morning, Erika began to interact with the northern Leeward islands of the Caribbean Sea, causing wind and rain. Later on September 2, Erika entered the Caribbean, still maintaining minimal tropical storm winds of 40 mph. Erika struggled westward, its center well west of the convection, similar to Tropical Storm Danny's appearance several days earlier. Erika meandered through the Caribbean for another day, before weakening to a tropical depression south of Puerto Rico on September 3. Overnight, Erika weakened into a remnant low. The next day, the low dissipated. Damage was minimal and no fatalities resulted from Erika.

Erika near peak intensity. Even then, Erika was very disorganized.

Track of Erika.