Hurricane Irene (2005)

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This article is about the Atlantic hurricane of 2005. For the 1999 hurricane that affected Florida, see Hurricane Irene (1999). For other uses, see the main article Tropical Storm Irene.

Hurricane Irene

Category 2 hurricane (SSHS)

Hurricane Irene on August 15, 3 days before dissipating

Formed

August 4, 2005

Dissipated

August 18, 2005

Highest
winds

105 mph (165 km/h) (1-minute sustained)

Lowest pressure

970 mbar (hPa; 28.66 inHg)

Fatalities

None reported

Damage

None

Areas
affected

East Coast of the United States

Part of the
2005 Atlantic hurricane season

Hurricane Irene was a long-lived Cape Verde-type hurricane during the 2005 Atlantic hurricane season. The August storm formed near the Cape Verde Islands and crossed the Atlantic, looping around Bermuda before becoming extratropical southeast of Newfoundland. Irene survived for 14 days as a tropical system, the longest survival of any storm of the 2005 season. It was the ninth named storm and fourth hurricane of that record-breaking season.

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 before being absorbed by a larger extratropical system late on August 18. Although there were 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.

1 Storm history
2 Impact, records and naming
3 See also
4 References
5 External links

[edit] Storm history

Storm path

A vigorous tropical wave moved off the coast of Africa on August 1, initially weakening due to cooler waters. It moved westward and passed near the Cape Verde Islands, where convection started to increase. The wave became more organized and developed into Tropical Depression Nine on the afternoon of August 4, 690 miles (1100 km) southwest of the Cape Verde Islands.^[1] 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 forecaster Dr Lixion Avila to comment, "How little we know about the genesis of tropical cyclones." ^[2] Despite the unfavorable conditions in its vicinity and its poor organization, Tropical Depression Nine continued to strengthen, becoming Tropical Storm Irene on August 7.^[1]

Irene as a Tropical Storm on August 12.

Because Irene was in an environment laden with dry air and high shear, it soon weakened to a tropical depression, on August 8.^[1] On the morning of August 10, as it was passing north of the Lesser Antilles, Irene nearly dissipated into a remnant low, with forecasters predicting that the storm would survive with "very low confidence".^[3] However, warm waters allowed Irene to become gradually more organized while south of Bermuda, and it became a tropical storm once again late on August 10.

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.^[4] 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.^[1] Though NHC meteorologists thought it was likely that Irene would become a hurricane, they were not expecting an intensification of such a magnitude.^[5]

Irene entered a region of increased wind shear and began to weaken, and as a result it was downgraded to a tropical storm late on August 17, when it was 520 miles (830 km) south of Cape Race, Newfoundland. Tropical Storm Irene finally became extratropical on August 18 after moving over much cooler waters, and was absorbed by a larger extratropical system later that day. Irene survived for 14 days as a tropical system, the longest survival of any storm of the 2005 season.^[1]

[edit] Impact, records and naming

As Hurricane Irene stayed well away from land, no coastal warnings or watches were issued for it. Despite Irene lasting for such a long time over the Atlantic, there were no reports of tropical storm force winds affecting ships. There were no damage or fatalities as a result of Irene.^[1] However, the hurricane generated strong waves and increased the risk of rip currents along the East Coast of the United States. Many beaches in New Jersey restricted swimming activities, and lifeguards at one beach performed more than a hundred rescues over a three-day period.^[6]

When Tropical Storm Irene formed on August 7, it was the earliest date for the formation of the ninth tropical storm in an Atlantic hurricane season, beating the previous record held by Storm Nine of the 1936 season by 13 days. This storm also marked the fifth occasion the name "Irene" had been used to name a tropical cyclone in the Atlantic, as well as the seventh occurrence worldwide. Due to the lack of any effects from Hurricane Irene, the name was not retired by the World Meteorological Organization and will be on the list of names for the 2011 season.