Hurricane Danielle, TS Earl, Hurricane Frank

Pre-Landfall 1 | Summary
Posting Date: August 26, 2010, 7:00:00 AM

The 2010 Atlantic hurricane season, which all major forecasting agencies expected to be well above average, may finally be showing signs of increased activity. Hurricane Danielle, the second hurricane and fourth named storm of the season, is churning in the mid-Atlantic with maximum sustained wind speeds of 105 mph, although it poses no immediate threat to land. The system developed from a tropical wave in the warm waters off the west coast of Africa near the Cape Verde Islands, strengthening to a tropical depression on August 21. From there it tracked northwest as it grew steadily more organized in the moist, low wind shear environment, eventually reaching Category 2 hurricane strength on the Saffir-Simpson scale on August 24. Encountering the unfavorable conditions of increased wind shear and drier air, Danielle briefly weakened to tropical storm status before restrengthening into a Category 2 hurricane. Because these “Cape Verde” type storms—common during the peak of the hurricane season—travel over water for a significant amount of time before threatening land, they have the potential to develop into some of the largest and most intense hurricanes. Indeed, as of the National Hurricane Center’s (NHC) 11:00 AM EDT advisory, Danielle is expected to intensify into major hurricane status within the next day or so, with expected maximum sustained winds of up to 115 mph (Category 3). Hurricane Danielle is currently located approximately 770 miles southeast of Bermuda and moving north-northwest at a forward speed of 15 mph, steered by a trough of low pressure in the mid-Atlantic Ocean. The storm is expected to maintain this general speed and direction over the next two days. On Saturday, a new trough of low pressure off the east coast of the United States is expected to steer Danielle due north. On its current projected path, Danielle is forecast to pass approximately 250 miles east of Bermuda on Sunday morning as a Category 3 hurricane before curving north-northeast. However, the NHC’s cone of uncertainty (representing 60–70% confidence in the forecast track) extends to within 100 miles of Bermuda. The Bermuda Weather Service has issued a small craft warning for large waves up to 9 ft, effective starting tomorrow evening. Meanwhile, Tropical Storm Earl, which strengthened from a tropical depression in the eastern Atlantic on Thursday, is located approximately 1600 miles east of the Lesser Antilles, as of the NHC’s 11:00 AM advisory. The storm is in a favorable environment for continued strengthening and is currently forecast to become a Category 1 hurricane on Saturday. With sustained maximum wind speeds of 45 mph, Earl is tracking west-northwest at 16 mph along the Atlantic trade winds and is expected to maintain this general direction for the next two days, at which point it may curve to the northwest. The NHC expects Earl to pass approximately 300 miles northeast of the Leeward Islands on Monday morning at Category 2 strength. However, because Earl is still in its formative stages, there is considerable uncertainty with regards to its track. In the eastern Pacific, Hurricane Frank, with maximum sustained wind speeds of 80 mph, is located approximately 380 miles south of Cabo San Lucas, Mexico and is moving west-northwest at 12 mph. By Saturday, the storm is expected to curve to the north toward the Baja peninsula, but it is forecast to gradually weaken and dissipate before landfall, if it makes one. While still a tropical storm, Frank brought heavy rains to some southern states of Mexico as it tracked along the coast from August 22 to August 23, causing some local flooding and landslides. As it moved farther away from the coast on August 24, the government of Mexico dropped all coastal warnings and watches. The AIR tropical cyclone team will continue to monitor all developments in the Atlantic and eastern Pacific and will provide updates as warranted by events. For information on current environmental conditions that may impact tropical storm activity (including sea-surface temperatures, wind shear conditions and steering currents), AIR offers a new service on the ALERT website called ClimateCast®.

Pre-Landfall 1 | Downloads
Posting Date: August 26, 2010, 7:00:00 AM