Sunday, August 22, 2010

Hurricane Danielle (2010)

Storm Active: August 21-30
On August 19, a broad area of low pressure formed just of the coast of Africa and quickly developed deep convection due to its proximity to the Intertropical Convergence Zone. Over the next day, the system developed two centers along the trough, one on the eastern side, toward Africa, and one on the western side. The one on the western side was 1008 mb, as opposed to the eastern's 1011 mb, and the former soon gained dominance as the other dissipated. During the day of August 20, the system remained disorganized. However, during the afternoon on August 21, a closed circulation formed, and a very apparent spin appeared on satellite images, and the disturbance was classified Tropical Depression Six that day with 30 mph winds and a pressure of 1008 mb. Six strengthened as it moved westnorthwest, and a burst of convection near the center merited an upgrade to Tropical Storm Danielle during the afternoon of August 22.

Favorable conditions with warm water and minimal wind shear allowed Danielle to strengthen significantly through the night and into August 23. By the afternoon of that day, Danielle reached hurricane strength and was still rapidly intensifying. Also, contrary to previous models, Danielle still continued on a generally westnorthwestward track overnight and into the next day. During the early morning of August 24, Danielle reached Category 2 hurricane strength. However, a dry air mass embedded itself in the system during the afternoon, briefly exposing the center! This caused Danielle to weaken to a tropical storm by the evening, but already it had recovered and started to regain strength. By early on August 25, Danielle's movement slowly was shifting to the northwest, although it was still westnorthwest for much of the morning.

The system was also a hurricane again by this time and gaining intensity. Danielle maintained an intensity of 85 mph winds and a pressure of 982 mb through the day, and turned northwest during the evening. Also, an eye feature began to develop during the night, albeit an asymmetrical one, as Danielle once again became a Category 2 hurricane. The eye had been clouded over due to the Eye Replacement Cycle, but Danielle still gained intensity into August 26. Danielle redeveloped a well-formed eye during the day, and its movement to the northwest slowed as a trough interfered with its motion. Danielle continued to strengthen, becoming the first major hurricane of the 2010 season at 2 am EDT on August 27, and became a Category 4 just three hours later with an amazing intensity of 135 mph winds and a minimum central pressure of 946 mb. Later that day, Danielle achieved its peak intensity of 135 mph winds and a central pressure of 942 mb.

After that, Danielle began to be exposed to some wind shear and cooler waters, resulting in some weakening. Danielle lost its major hurricane status early on August 28, and continued its downward trend during that day as it turned to the north. During the day of August 28, Danielle, despite being over 1000 miles from the east coast, influenced the surf along the coastline, and created 3-6 foot waves and rip currents, killing one person in Florida. However, a trough moving off the east coast picked up Danielle and began to steer it to the east. That evening, Danielle's circulation broadened and became asymmetrical, marking the beginning of its extratropical transition. This transition continued into August 29, as the cyclone accelerated northeast and weakened to a Category 1 hurricane. By August 30, it was clear that Danielle was nearly extratropical and barely holding on to minimal hurricane strength, but it somehow stayed tropical through the day and turned more eastward, weakening to a tropical storm. However, by 11:00 pm EDT on August 30, Danielle had become fully extratropical and the last advisory was issued.

Danielle's remnants became embedded in a frontal boundary the next day, and it dissipated soon after as it sped off to the east. No damage and 1 indirect death occurred from Danielle.

Danielle near peak intensity over the open waters of the Atlantic.

Track of Danielle.

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