2006 Atlantic Hurricane Season - Season Summary

Season Summary

See also: Tropical Storm Zeta (2005) and Timeline of the 2006 Atlantic hurricane season

Tropical Storm Zeta formed on December 30, 2005, and lasted until January 6, 2006. Although the majority of its existence was spent in 2006, it is officially a storm of the 2005 Atlantic hurricane season because that is the year in which it formed. Zeta joined Hurricane Alice as only the second North Atlantic tropical cyclone in recorded history to span two calendar years.

The season started on June 1, 2006, and officially ended on November 30, 2006. These dates conventionally delimit the period of each year when most tropical cylones form in the Atlantic basin. Ten days into the start of the season, Tropical Storm Alberto developed in the Caribbean Sea, and after four months of activity, Hurricane Isaac dissipated on October 3 south of Newfoundland. Compared to the devastating 2005 Atlantic hurricane season, 2006 was not severe in terms of deaths and damage.three tropical storms made landfall in the United States. The first of them, Tropical Storm Alberto, made landfall in Florida with winds of 50 mph (80 km/h), causing flooding and light damage. Tropical Storm Beryl made landfall on Nantucket, but left little impact. The third and more significant storm was Hurricane Ernesto, which killed two people in Virginia and two in Florida, as well as causing $500 million in damage (2006 USD). During the season, only one tropical cyclone in the Atlantic – Alberto – affected Mexico. Canada was affected by several tropical cyclones during 2006, including Alberto, the unnamed storm, Beryl, Florence, and Isaac.

On June 20, an upper-level disturbance formed east of the Bahamas and moved westward across the islands. Between June 24 and 26, areas of convection developed occasionally, and a low-level disturbance formed. The system turned northward and upon reaching the Gulf Stream on June 27, it began to mature. It made landfall near Morehead City, North Carolina and moved northeastward along the U.S. East Coast. The storm contributed to severe and deadly flooding in the Mid-Atlantic States. While the NHC did not operationally classify it, data from reconnaissance aircraft, NEXRAD weather radar, and surface observations suggest it may have met the criteria for a tropical cyclone.

The National Hurricane Center's pre-season activity outlook predicted 13–16 named storms, 8–10 hurricanes and 4–6 major hurricanes. They also predicted a high risk of at least one major hurricane strike to the Southeast United States. In the event, only ten storms formed during the season, the lowest number since the 1997 season, when there were seven. Five of the ten storms developed into hurricanes—also the lowest number since 1997—and only two attained major hurricane status, tying with 2002 for the fewest since 1997. Only one named storm was observed during October, the lowest number since 1994, when none were seen during that month. Additionally, only three named storms made landfall in the United States, the fewest since 2001. Because of several factors, including a rapidly forming El Niño event, the Saharan Air Layer over the tropical Atlantic and the presence of a high pressure area to the Azores high situated near Bermuda, it contributed to a below average season. Also, sea surface temperatures in the western Atlantic were just at or slightly below average. In contrast, sea surface temperatures during the 2005 season were well above average.

Overall, the season's activity was reflected with a low cumulative accumulated cyclone energy (ACE) rating of 79. ACE is, broadly speaking, a measure of the power of the hurricane multiplied by the length of time it existed, so storms that last a long time, as well as particularly strong hurricanes, have high ACEs. ACE is only calculated for full advisories on tropical systems at or exceeding 34 knots (39 mph, 63 km/h) or tropical storm strength. Subtropical cyclones are excluded from the total.