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The 2006 Atlantic hurricane season was the least active in the basin since 1997, with nine named storms as well as an additional unnamed tropical storm identified by the National Hurricane Center. 2006 was the first season since 2001 in which no hurricanes made landfall in the United States, and was the first since 1994 in which no tropical cyclones formed during October. Following the intense activity of 2003, 2004, and 2005, forecasters predicted that the 2006 season would be only slightly less active. Instead, it turned out to be a below average season, as activity was slowed by a rapidly forming moderate El Niño event, the presence of the Saharan Air Layer over the tropical Atlantic, and the steady presence of a robust secondary high-pressure area to the Azores High centered on Bermuda. There were no tropical cyclones after October 2.
The season began on June 10 with the formation of Tropical Storm Alberto, which moved from the Caribbean Sea through the east coast of the United States. Hurricane Ernesto caused heavy rainfall in Haiti, and directly killed at least seven in Haiti and the United States. Four hurricanes formed after Ernesto, including the strongest storms of the season, Hurricanes Helene and Gordon. In total, the season was responsible for 14 deaths and $500 million in damage. The calendar year 2006 also saw Tropical Storm Zeta, which arose in December 2005 and persisted until early January, only the second such event on record. The storm is considered a part of the 2005 season, as it developed in that calendar year.
Seasonal forecasts
Forecasts of hurricane activity are issued before each hurricane season by Philip J. Klotzbach, Dr. William M. Gray, and their associates at Colorado State University; and separately by NOAA forecasters.
Klotzbach's team (formerly led by Gray) has defined the average number of storms per season (1950–2000) as 9.6 tropical storms, 5.9 hurricanes, and 2.3 major hurricanes (storms exceeding Category 3 strength in the Saffir–Simpson scale). A normal season, as defined by NOAA, has 6–14 named storms, with 4–8 of those reaching hurricane strength, and 1–3 major hurricanes.
{| class="toccolours" cellspacing=0 cellpadding=3 style="float:right; margin-left:1em; text-align:right; clear: right;"
|+Predictions of tropical activity in the 2006 season
|- style="background:#CFCFCF; text-align:center;×÷≥"
|align="center"|Source
|align="center"|Date
|align="center"|<span style="font-size: 80%;">Named<br />storms</span>
|align="center"|<span style="font-size: 80%;">Hurricanes</span>
|align="center"|<span style="font-size: 80%;">Major<br />hurricanes</span>
|-
|align="left"|CSU
|align="left"|Average <span style="font-size: 80%;">(1950–2000)</span>
|6–14
|4–8
|1–3
|-
|align="center" colspan="2"|Record high activity from 1950–2006
|28
|15
|7
|-
|align="center" colspan="2"|Record low activity from 1950–2006
|4
|2
|0
|-
|align="left"|CSU
|align="left"|December 5, 2005
|17
|9
|5
|-
|align="left"|CSU
|align="left"|April 4, 2006
|17
|9
|5
|-
|align="left"|NOAA
|align="left"|May 22, 2006
|13–16
|8–10
|4–6
|-
|align="left"|CSU
|align="left"|May 31, 2006
|17
|9
|5
|-
|align="left"|CSU
|align="left"|August 3, 2006
|15
|7
|3
|-
|align="left"|NOAA
|align="left"|August 8, 2006
|12–15
|7–9
|3–4
|-
|align="left"|CSU
|align="left"|September 1, 2006
|13
|5
|2
|-
|align="left"|CSU
|align="left"|October 3, 2006
|11
|6
|2
|-
|align="center" colspan="2"|Actual activity
| 10
| 5
| 2
|}
Pre-season forecasts
On December 5, 2005, Klotzbach's team issued its initial extended-range forecast for the 2006 season, predicting an above average of 17 named storms, nine of them hurricanes, and five classified as Category 3 intensity or higher.
On May 22, 2006, NOAA released its pre-season forecast for the 2006 season. The prediction was for 13–16 named storms, 8–10 of those becoming hurricanes, and 4–6 becoming major hurricanes.
Midseason outlooks
On August 3, 2006, Klotzbach's team lowered its season estimate to 15 named storms, with 7 becoming hurricanes and 3 becoming major hurricanes, noting that conditions had become less favorable for storms than they had been earlier in the year. The sea-level pressure and trade wind strength in the tropical Atlantic were reported to be above normal, while sea surface temperature anomalies were on a decreasing trend.
On August 8, 2006, NOAA revised its season estimate to 12–15 named storms, with 7–9 becoming hurricanes, and 3–4 becoming major hurricanes. The reduction was attributed to less favorable environmental conditions, a decrease in La Niña conditions, and the lack of a "very persistent upper-level ridge pattern over the eastern U.S. and western Atlantic".
On September 1, Klotzbach's team also revised its season estimate, to 13 named storms, 5 hurricanes, and 2 major hurricanes, citing a larger volume of the Saharan Air Layer and an El Niño trend in the Pacific. The team again reduced the number of tropical storms expected for the season a month later, on October 3, with an updated forecast of 11 named storms, 6 hurricanes, and 2 major hurricanes, citing the ongoing El Niño.
Seasonal summary
195px|thumb|Satellite image on September 18 of Hurricane Gordon on the top, with Hurricane Helene to the bottom
Tropical Storm Zeta formed on December 30, 2005, and lasted until January 6, 2006. Although the majority of its existence occurred in 2006, it is officially a storm of the 2005 Atlantic hurricane season as 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 cyclones form in the Atlantic basin. Ten days into the start of the season, Tropical Storm Alberto developed in the Caribbean, During the season, only one tropical cyclone in the Atlantic – Alberto – affected Mexico.
left|thumb|A graph showing averages and statistics for Atlantic hurricane seasons
The National Hurricane Center's pre-season activity outlook predicted 13–16 named storms, 8–10 hurricanes and 4–6 major hurricanes. 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 78.5. 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 or tropical storm strength. Subtropical cyclones are excluded from the total.
Systems
Tropical Storm Alberto
On June 10, an area of disturbed weather associated with a broad low-pressure area off the coast of Belize organized over the warm waters of the Caribbean into the first tropical depression of the season. Southwesterly vertical wind shear initially prevented significant development, but as it moved closer to Florida, the depression strengthened into a tropical storm on June 11. Passing over the warm, deep water of the Loop Current allowed accelerated development, and the cyclone reached its peak winds of , just shy of hurricane strength. Subsequent weakening occurred as it moved over the cooler waters of the continental shelf, and Alberto made landfall near Adams Beach, Florida, on June 14 with winds of about .
Alberto caused record rainfall in North Carolina, peaking at . In Florida, two people died, and damage was estimated at $250,000 (2006 USD). Later, the storm left four sailors missing about south of Nova Scotia. It decayed and dissipated, leaving behind two areas of low pressure. The southern area near North Carolina became Tropical Storm Beryl, and the northern system became an extratropical low on July 16, south-southeast of Cape Cod, Massachusetts. The system separated itself from the dissipating front later that day while moving northeastward over warm waters. Convection developed near the center, and the system transitioned into a tropical depression early on July 17, about southeast of Nantucket, Massachusetts. The system was broad and ill-defined at first, although the low-level circulation became sufficiently organized to be designated a tropical depression on July 18, about 290 mi (465 km) east-southeast of the coast of North Carolina. Later that day, the depression developed organized rainbands over the eastern periphery of the circulation, and as a result, the NHC upgraded it to Tropical Storm Beryl. The nascent storm moved generally northward at first along the western periphery of a subtropical ridge, parallel to the East Coast of the United States. With low wind shear and favorable outflow, Beryl intensified to reach a peak intensity of early on July 20. Cooler waters caused Beryl to weaken, as it turned northeastward ahead of an approaching trough. Early on July 21, the storm struck the island of Nantucket with winds of 50 mph (85 km/h). Shortly thereafter, Beryl transitioned into an extratropical cyclone, which moved through Nova Scotia before merging with another extratropical cyclone on July 22 over Newfoundland. Waves along the southern coast of Nantucket reached in height as the storm approached the island, resulting in four people being rescued by lifeguards from rip currents. Light rainfall, reaching , was recorded on Nantucket, and wind gusts reached . The remnants of Tropical Storm Beryl dropped moderate precipitation in Atlantic Canada, with totals of up to ; in some locations of rain fell in an hour. Moderate winds were reported along its path, which peaked at in southern Nova Scotia. The storm caused minor street flooding and power outages across Atlantic Canada.
Tropical Storm Chris
In late July, a tropical wave moved off the coast of Africa and traversed the Atlantic Ocean. The associated convection organized and became a tropical depression on August 1 about east of Antigua. The depression tracked westward and soon intensified into Tropical Storm Chris before reaching peak winds of northeast of the United States Virgin Islands. The storm was forecast to strengthen further and become a hurricane as it moved into the Bahamas. However, Chris began to be affected by wind shear and became disorganized. The storm weakened to a tropical depression on August 4, and dissipated as it approached the Cuban coast on August 5.
The storm's effects were limited to moderate rainfall in Hispaniola and Cuba. Cruise lines such as Royal Caribbean re-routed their ships to avoid the storm. The storm dropped light rainfall in Puerto Rico, peaking at in Fajardo. The rainfall from the storm caused the Fajardo River to overflow its banks, which temporarily closed a highway in the northeastern portion of the island.Rainfall reached up to 2 inches (50 mm) across portions of Hispaniola, the Turks and Caicos, the Bahamas, and eastern Cuba, and reached in some mountainous areas. In Santo Domingo in the Dominican Republic, heavy rainfall caused severe flooding. Las Américas reported of rainfall from Chris. Several people were left temporarily homeless due to flooding entering their households. The flooding left many roads impassable near the capital city, and also resulted in landslides. The flooding also covered rice fields in the northeastern portion of the country. The National Office of Meteorology issued flood warnings for residents in low-lying areas and near rivers in the northeast and southeast portions of the country. Overall damage was minor.
Tropical Storm Debby
On August 20, a vigorous tropical wave exited the coast of Africa, developing convective banding and a broad circulation. A broad area of low pressure formed within the wave the next day and despite convection weakening, the area of low pressure remained well-organized, becoming Tropical Depression Four later that day with water temperatures and minimal upper-level shear conducive for further intensification. The next day, the depression intensified into Tropical Storm Debby about 300 mi (485 km) southwest of Cape Verde. Convection redeveloped over a portion of the center, while banding features redeveloped as well. Organization continued, and Debby once again peaked with the next day. Soon after, southerly wind shear displaced the convection to the north of the center, causing Debby to weaken into a tropical depression the next day. Soon after, Debby degenerated into a remnant low. The remnants of Debby persisted before dissipating on August 28. However, all warnings were discontinued six hours later, the depression moved away from the islands. Despite that, the depression produced a gust of 35 mph (55 km/h) at Fogo Despite Debby being forecast to remain far away from the Gulf of Mexico, investors tracking the storm caused the price of crude oil to rise significantly due to its potential impact to oil installations.
Hurricane Ernesto
Hurricane Ernesto originated from a tropical wave which moved off the coast of Africa on August 18. The wave progressed westward and reached the Western Atlantic, spawning a tropical depression on August 24 near the Windward Islands. It moved west-northwestward through the Caribbean Sea and intensified into Tropical Storm Ernesto on August 25. The storm briefly attained hurricane status on August 27 to the southwest of Haiti, before land interaction caused weakening. Ernesto made landfall near Guantánamo Bay, Cuba, early in the morning on August 28 as a tropical storm. At one point the storm was predicted to become a major hurricane in the Gulf of Mexico and threaten parts of the Gulf Coast. However, Ernesto moved much farther east than anticipated, and made landfall as a tropical storm on the southern tip of Florida on August 29. Ernesto retained tropical storm strength as it crossed Florida and emerged from land near Cape Canaveral, and was just below hurricane strength when it made landfall again in North Carolina on August 31. Ernesto transitioned into an extratropical cyclone over Virginia on September 1, which ultimately dissipated over Quebec on September 4.
Large swells, rip tide, and undertow were reported on Bermuda, the Leeward Islands, the Virgin Islands, and Hispaniola. Florence affected Bermuda with wind gusts up to and heavy rain which left 23,000 houses without electricity. In all, the storm caused $200,000 (2006 USD; $ USD) in damage. Florence then brought heavy rains across Newfoundland as an extratropical storm, destroying one house and causing minor damage to several others. There were no fatalities as a result of the hurricane.
Hurricane Gordon
A tropical wave moved off the coast of Africa on September 1. The wave tracked westward across the Atlantic for several days until it reached an area of relaxed wind shear and its associated low-pressure area organized into a tropical depression. It moved east-northeast and was upgraded to Tropical Storm Gordon on September 11, while located over the open waters of the Atlantic. Gordon turned north, and became a hurricane on September 13. It intensified to Category 3 status on the Saffir–Simpson scale and reached its peak intensity of on September 14. Tracking northward, it began to lose tropical characteristics. On September 20, the system affected Britain with high winds and heavy rain as an extratropical cyclone. During Gordon's passage through Britain, 120,000 homes were left without power after winds of affected the country.
Hurricane Helene
On September 11, a vigorous tropical wave moved off the west coast of Africa, which the NHC expected would develop into a tropical cyclone. The convection increased and organized further, leading to the development of a tropical depression on September 12, located 270 mi (370 km) south-southeast of the Cape Verde Islands. While passing south of the islands, the depression struggled to intensify due to easterly wind shear and the cyclone's large size. Improved rainbands developed over the northern periphery, signaling that the depression intensified into Tropical Storm Helene on September 14. A day later, as wind shear decreased, Helene began intensifying, reaching hurricane intensity on September 16, as it developed a ragged eye in the center of the convection. On September 17, the intensification became more rapid and Helene quickly became a Category 2 hurricane that morning as the eye became clearer and surrounded by deep convection. Helene also turned more northward and slowed in the central Atlantic, which was in response to a weakness in the subtropical ridge farther north created by Gordon to the north. Early on September 18, Helene peaked as a Category 3 hurricane with winds of . Further weakening occurred on September 20 as wind shear increased. A day later, Helene turned back to the north and later northeast ahead of a trough that exited the east coast of the United States. Helene remained a warm-core cyclone until September 24, when it transitioned into an extratropical cyclone northwest of the Azores. Continuing northeast, the cyclone passed near Iceland on September 27. Later that day, the remnants of Helene merged with another larger extratropical cyclone north of the British Isles. As a weakened extratropical system, strong wind gusts were reported in Ireland and northern Scotland. The strongest reported wind gust in Ireland was at the Valentia Observatory, where gusts were reported. In Scotland, the strongest gust was on South Uist Island in the Outer Hebrides, where gusts were reported. Around that time, a ragged eye feature appeared on satellite imagery.
After reaching peak intensity, Isaac curved the periphery of the subtropical ridge, turning to the north-northeast. Stronger wind shear and cooler waters caused Isaac to weaken to a tropical storm on October 2. That day, Isaac passed about to the southeast of the Avalon Peninsula of Newfoundland. At Cape Race, sustained winds peaked at , with gusts of up to . Shortly after passing the island, Isaac transitioned into an extratropical cyclone, and on October 3 the remnants merged with a larger extratropical storm. This is the same list used for the 2000 season, except for Kirk, which replaced Keith. No names were used for the first time in 2006. No names were retired following the season for the first time since the 1997 season, and this list was used again for the 2012 season.
{| style="width:90%;"
|
- Alberto
- Beryl
- Chris
- Debby
- Ernesto
- Florence
- Gordon
|
- Helene
- Isaac
|
|}
Season effects
This is a table of all of the storms that formed in the 2006 Atlantic hurricane season. It includes their name, duration, peak classification and intensities, areas affected, damage, and death totals. Deaths in parentheses are additional and indirect (an example of an indirect death would be a traffic accident), but were still related to that storm. Damage and deaths include totals while the storm was extratropical, a wave, or a low, and all of the damage figures are in 2006 USD.
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See also
- Tropical cyclones in 2006
- 2006 Pacific hurricane season
- 2006 Pacific typhoon season
- 2006 North Indian Ocean cyclone season
- South-West Indian Ocean cyclone seasons: 2005–06, 2006–07
- Australian region cyclone seasons: 2005–06, 2006–07
- South Pacific cyclone seasons: 2005–06, 2006–07
- South Atlantic tropical cyclone
- Mediterranean tropical-like cyclone
References
External links
- National Hurricane Center 2006 Advisory Archive
- HPC's Rainfall Page for tropical cyclones which affected the United States in 2006
- Unisys' 2006 Season Page – includes map of paths of all storms
- Flash Hurricane Tracker – track active and archived hurricanes.
- NRL hurricane page – Naval Research Laboratory page with extensive archives on individual storms
- 2006 Hurricanes – Free Google Earth Hurricane tracker