page_title: Hurricane Irene (2005)
section_title: Meteorological history
hierarchical_section_title: Hurricane Irene (2005) / Meteorological history
caption_attribution_description: English: Irene was building towards a hurricane when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured this image at 2:20 p.m. U.S. Eastern Daylight Savings Time on August 14, 2005. By 11 p.m., Irene had become the third hurricane of the 2005 Atlantic hurricane season. The storm is moving northeast along the east coast of the United States and is not expected to make landfall, by National Hurricane Center predictions. Along the top of the image, a pall of haze hugs the coast, blowing out over the Atlantic over the Chesapeake Bay. Such haze develops when hot, muggy weather caused by a high pressure system traps stagnant air. Emissions from cars and power plants build up, leading to hazy skies. The U.S. Environmental Protection Agency’s AirNow web site warned that air quality levels in the Mid-Atlantic states would be unhealthy for sensitive groups to unhealthy for all groups on August 13. Clearly, haze continued to affect the region on the following day. The large image provided above has a resolution of 500 meters per pixel. The MODIS Rapid Response Team provides the image in additional resolutions, including MODIS’ maximum resolution of 250 meters per pixel.
context_page_description: Hurricane Irene was a long-lived Cape Verde hurricane during the 2005 Atlantic hurricane season. The storm formed near Cape Verde on August 4 and crossed the Atlantic, turning northward around Bermuda before being absorbed by an extratropical cyclone while situated southeast of Newfoundland. Irene proved to be a difficult storm to forecast due to oscillations in strength. After almost dissipating on August 10, Irene peaked as a Category 2 hurricane on August 16. Irene persisted for 14 days as a tropical system, the longest duration of any storm of the 2005 season. It was the ninth named storm and fourth hurricane of the record-breaking season.
  Although there were initial fears of a landfall in the United States due to uncertainty in predicting the storm's track, Hurricane Irene never approached land and caused no recorded damage; however, swells up to 8 ft and strong rip currents resulted in one fatality in Long Beach, New York.
context_section_description: Hurricane Irene began as a Cape Verde storm. A vigorous tropical wave moved off the west coast of Africa on August 1, initially weakening due to cooler sea surface temperatures. It moved westward and passed near Cape Verde, where convection started to increase. The system subsequently developed into a tropical depression on the afternoon of August 4, 690 miles (1100 km) southwest of the Cape Verde Islands. Early on August 5, the depression abruptly turned to the northwest into an area of higher wind shear, causing some computer models to predict that the depression would dissipate, while others predicted steady strengthening. The sudden threat to the storm's existence prompted National Hurricane Center (NHC) forecaster Lixion Avila to comment, "How little we know about the genesis of tropical cyclones." Despite the unfavorable conditions in its vicinity and its poor organization, Tropical Depression Nine continued to strengthen, becoming Tropical Storm Irene on August 7.
  Because Irene was in an environment laden with dry air and high shear, it soon weakened to a tropical depression, on August 8. On the morning of August 10, as it was passing north of the Lesser Antilles, Irene nearly dissipated into a remnant low, but forecasters predicted with "very low confidence" that the storm would survive. Contrary to these expectations, warmer waters and less wind shear allowed Irene to become gradually more organized while south of Bermuda, and it became a tropical storm once again early on August 11.
  Due to uncertainties about how the region's subtropical ridge would interact with Irene, the models continued to give unclear signals of the storm's future. Some of the models predicted that Irene would make landfall in North Carolina, while others continued to anticipate that Irene would dissipate. The uncertainty ended when a weakness in the subtropical ridge allowed Irene to turn sharply northward, which caused the storm to pass midway between the Outer Banks of North Carolina and Bermuda on August 15. Soon after, upper-level shear weakened greatly, and Irene rapidly intensified, first to a hurricane, then to its peak strength as a 105 mph (170 km/h) Category 2 hurricane on the afternoon of August 16, while located 350 miles (560 km) northeast of Bermuda; at the same time it also attained minimum pressure of 970 mbar. Though NHC meteorologists thought it was likely that Irene would become a hurricane, they were not expecting an intensification of such a magnitude.
  Irene entered a region of increased wind shear and began to weaken, and as a result it was downgraded to a tropical storm early on August 18, when it was 520 miles (830 km) south of Cape Race, Newfoundland. All convection within 230 mi (370 km) of the cyclone dissipated on August 18. Irene was subsequently absorbed by an extratropical cyclone later that day. Irene lasted for 14 days as a tropical system, the longest duration of any storm of the 2005 season.
caption: Tropical Storm Irene off the United States East Coast on August 14
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