2011 Atlantic hurricane season

The 2011 Atlantic hurricane season officially began on June 1 and ended on November 30. During this period, make the most tropical storms, since only at this time suitable conditions, such as a warm ocean, moist air and little wind shear, exist to allow the formation of tropical cyclones.

• 2.1 Tropical Storm Arlene
• 2.2 Tropical Storm Bret
• 2.3 Tropical Storm Cindy
• 2.4 Tropical Storm Don
• 2.5 Tropical Storm Emily
• 2.6 Tropical Storm Franklin
• 2.7 Tropical Storm Gert
• 2.8 Tropical Storm Harvey
• 2.9 Hurricane Irene
• 2:10 Tropical Depression Ten
• 2:11 Tropical Storm Jose
• Hurricane Katia 2:12 / hurricane (ex ) Katia
• 2:13 Untitled tropical storm
• 2:14 Tropical Storm Lee
• 2:15 Hurricane Maria
• 2:16 Hurricane Nate
• 2:17 Hurricane Ophelia
• 2:18 Hurricane Philippe
• Hurricane Rina 2:19
• 2:20 Tropical Storm Sean

Season forecasts

Predictions about the activity of the coming hurricane season will be created each year by the hurricane experts Philip J. Klotzbach and William M. Gray and her staff at Colorado State University and separately by the meteorologists at the NOAA, and the consortium Tropical Storm Risk.

Klotz 's team defined the average number of storms per season on average (1950-2000) to 9.6 tropical storms, 5.9 hurricanes and 2.3 major hurricanes ( ie, those at least on the Saffir -Simpson Hurricane Scale are classified to category 3 ). A normal season, as it was defined by the NOAA, consists of 9-12 named storms, 5-7 of which reach hurricane strength and 1-3 major hurricanes.

Predictions before the season

On 8 December 2010 Klotz 's team predicted an above-average activity with 17 named storms in a first forecast for the Atlantic hurricane season of 2011. From the team is expected that it will be nine storms into a hurricane, with five of them reach at least Category 3. The team also went from a Accumulated Cyclone Energy (ACE ) from about 165 and stated that the formation of El Niño conditions is unlikely before the start of hurricane season. Finally, the team stated in its prediction that the probability of storms that will make landfall in the United States was greater than in 2010.

Tropical Storm Risk ( TSR), belonging to a consortium at University College London, the experts in the fields of insurance, risk management and climatic season predictions, gave a similar assessment known several days before the team of the CSU. TSR is based on a tropical cyclone activity, which might be about forty percent higher than the average for the years 1950-2010. In the TSR forecast expects 15.6 ( ± 4.3 ) tropical storms, 8.4 ( ± 3.0 ) hurricanes and 4.0 ( ± 1.7 ) major hurricanes (values ​​in parentheses indicate the error band on ), the ACE was predicted by TSR to 141 (± 58).

The April 6, published forecasts of Klotz 's team is comprised only minor changes. According to the April 2011 forecast sixteen named storms could occur in the season, of which nine would become hurricanes and five of them to hurricanes of Category 3 or higher.

The Climate Prediction Center of NOAA announced on May 19 its pre-season forecast known. Accordingly, the NOAA expects at a probability of 70 percent with 12-18 named storms, including 6-10 hurricanes, of which three to six are likely to develop into major hurricanes. The expected Accumulated Cyclone Energy (ACE ) is estimated at 105-200 percent of the median of the years 1981 to 2010. The forecast put the climatologists NOAA the persistence of the begun in 1995 warm phase of the Atlantic Multi- decadal Oscillation ( AMO), the continued high level of water surface temperatures in the tropical Atlantic Ocean and the Caribbean Sea as well as the decaying over the summer La Niña effect and the adoption of the following normal phase of the El Niño - Southern Oscillation based.

The Met Office ( UKMO ) published on May 26, his prediction of a slightly above average active hurricane season with 13 named storms and a 70 - percent probability that the number of 10 to 17 would be. However, the Met Office makes no differentiation in terms of intensity, so had not a number of hurricanes and major hurricanes from. The Institute predicted an ACE value of 151 and that the ACE - value will lie with 70 percent probability, 89-212.

Storms

Tropical Storm Arlene

On the evening of June 28 ( local time) was formed in the Gulf of Mexico, the first tropical storm of the season. He was moving at 11 km / h in west- northwesterly direction toward the Mexican coast. Its central pressure was 1003 hPa and the wind speed in the center was around 65 km / h Later the system to up to 100 km / h increased before reaching Mexican mainland on the morning of June 30 ( local time) between Tuxpan and Tampico Cabo Rojo. In the evening (local time) the same day, Arlene broke up in the mountains of the Sierra Madre Oriental. By caused by the remaining remnant low heavy rains two people have been killed, according to the Mexican authorities in the central highlands of Mexico.

Tropical Storm Bret

Mid-July, extended westward across the North Atlantic, a cold front, stationary was the westernmost component near Florida. On 16 July, the Bahamas developed along the weakening front north, a low pressure area that organized itself better under decreasing amount of wind shear. It formed a closed circulation, so that the NHC on July 17 at 21:00 UTC clock, the formation of the second tropical depression of the season the area reported that as the center was about 160 km northwest of Great Abaco Island Iceland. It strengthened within three hours to a tropical storm and was named Bret. The system moved only slightly, while Bret further intensified and increased the thunderstorm activity around the center. The storm developed on 18 July, a similar feature eyes and developed with wind speeds around 100 km / h its greatest strength, before announcing it was moving in a northeasterly direction. Although strong wind shear and dry air masses hindered the further development, Bret kept in the following two days at a well-organized circulation and a persistent thunderstorm activity. However, the center broke away from the convection and then Bret weakened on 22 July to tropical depression off. Despite very unfavorable conditions Bret remained several hours a tropical system, then broke up about 600 km north of Bermuda.

Tropical Storm Cindy

On July 19, emerged from the weather front that was involved in the formation of Tropical Storm Bret, a large low pressure system over the North Atlantic. The system quickly moved eastward and formed to be the center of circulation is minimal convection from, yet the NHC saw the potential for a further tropical or subtropical development. The low intensified and appeared better defined so that it after the convection on the warm center of the circulation revived closer, was classified as Tropical Storm Cindy on July 20 at 21:00 UTC clock. The center was located 1065 km east-northeast of Bermuda at this time. At the time of formation, the cyclone was in a strong southwest flow of air along the subtropical ridge, so for most of the existence of the system a fast, steady northeastward directed migration was expected. Cindy stepped up to the climax with wind speeds of 110 km / h and a minimum central pressure of 994 hPa, the train speed of the system increased, and a strong front in the north-west caused a wind shear. Late on July 22, the final warning was issued at Cindy, because the system is dissolved by the strong wind shear. The remnant low sped to the northeast of it until it came up in the southern region of the extratropical system.

Tropical Storm Don

The fourth tropical depression of the season formed on July 27, 2011 north of the Yucatán Peninsula in the Gulf of Mexico from a tropical wave that moved long time undeveloped west through the Caribbean. Hurricane Hunters have measured in their mission winds of about 39 mph and 1001 -mb central pressure, which is why the system was declared a tropical storm. The system was moving towards the west -northwest toward the coast of the U.S. state of Texas. For the coastal areas immediately a storm warning has been issued.

Tropical Storm Emily

A strong tropical wave moved the end of July for several days over the open tropical Atlantic. However, the wave remained fairly disorganized and lacked a well-defined circulation. The system slowly organized better than it was on July 31, approached the Leeward Islands, where the storm led to violent weather conditions. Late on August 1, a closed circulation found the Hurricane Hunters ago during a reconnaissance flight. The system was then classified by the National Hurricane Center directly as Tropical Storm Emily, shortly after the center of the storm had crossed the Antilles arc.

The system continued to move towards Haiti, which is only slightly increased. However, there was still not well organized upon arrival on August 4, so that Emily at the crossing of the Haitian mainland greatly lost its force and moved just as so-called tropical wave in the direction of Cuba. Nevertheless, the remnant low brought heavy rainfall to the west of the island of Hispaniola (Haiti, Dominican Republic) and the East of Cuba.

Two days later, the remnant low reactivated over the northern Bahamas Islands and was reclassified as a tropical depression. The next day, the system broke up again.

Tropical Storm Franklin

On August 10, formed off the east coast of Florida, a disorganized area of ​​showers and thunderstorms, which was connected to an elongated area of ​​low pressure in combination. The system moved slowly to the northeast, the fault it developed slowly; the morning of 12 August, however the chances of developing further were low in a tropical system. During the following hours, the thunderstorm activity, however, noticeably organized in a zone around a well-defined area of ​​low pressure. The system was therefore declared in the course of the day for the sixth tropical depression of the season and was located about 420 kilometers north of Bermuda at this time.

The system maintained a northeastern course and intensified early on 13 August after a major outbreak of convection in its center to Tropical Storm Franklin. Before noon, reached Franklin with a sustained wind speed of 75 km / h its greatest strength, but then hit on increasing Windgescherung and came over cooler water. A rapid decay of the structure of the storm followed, as because the conditions for a tropical system were increasingly unfavorable. The convection was displaced by more than 150 km from the circulation center and Franklin began to take extratropical characteristics. Early on August 14 FULL Franklin in the North Atlantic, the transition an extratropical system, which is why the NHC issued the final warning. The next day, the low disintegrated west of Ireland.

Tropical Storm Gert

In the second week of August, a weak low pressure area was east of Bermuda. By 13 August, the low pressure area was very well defined. Therefore, it was named on the same day as a tropical depression seven and that day was about 360 km south- southeast of Bermuda. It intensified quickly and became Tropical Storm Gert. Gert was approaching Bermuda. At the same time achieved Gert its peak with winds of 100 km / h Gert brought rain and wind of 40 km / h on the islands. On August 16, Gert weakened greatly and became an extratropical storm over the open Atlantic, where he soon broke up.

Tropical Storm Harvey

In mid-August came a moving westward tropical wave in the Caribbean. It eventually gained enough organization to be classified as Tropical Depression Eight on August 18. On August 19 it was upgraded to Tropical Storm Harvey. Later on August 19, the storm intensified rapidly and it was announced that Harvey just before landfall, a hurricane is. But on August 20, Harvey made ​​landfall, but never with hurricane strength. Harvey was then downgraded to a low pressure area and dissipated on August 22.

Hurricane Irene

On the evening of August 20 was a large area of ​​low pressure enough to be classified as Tropical Storm Irene. It attracted early on 21 August over the Leeward Islands. Early on August 22, Irene strengthened into a Category 1 hurricane with winds of 120 km / h and a central pressure of 987 hPa So Irene was the first hurricane of the season. Early on August 24, Irene was upgraded to a Category 3 hurricane with winds of 185 km / hr. On August 27, Irene made ​​landfall on the coast of North Carolina as a Category 1 hurricane with winds of 140 km / h and an unusually low air pressure. Hurricane Irene made ​​a second U.S. landfall in New Jersey at 5:35 clock, so it was the first hurricane since 108 years, made landfall in New Jersey. On August 28, Irene was downgraded to a tropical storm and made around 9:00 clock its third U.S. landfall in Brooklyn, New York City. Irene was an extratropical storm over Quebec, Canada on August 29. As a result, there remained a few days as powerful Iceland low, and fell apart there at 3 September.

Irene killed at least 56 people, ten U.S. states and Canada were affected by damage. Irene was the zwölftteuerste hurricane history. It caused a loss of 10.1 billion U.S. dollars.

Tropical Depression Ten

On August 21, a tropical wave left the west coast of Africa. During the next four days, the tropical wave moved into the Atlantic and slowly intensified. On August 25, it was in the eastern Atlantic to the tropical depression ten. However, the low pressure area remained poorly organized and broke up just one day later, on August 26, again.

Tropical Storm Jose

On August 17, a tropical wave left the west coast of Africa. During the first few days, the tropical wave generated convection and they moved slowly to the west. But in the next week was the wave to a weak area of ​​low pressure. The depression was moving at the time to the northwest, while the intensity was somewhat varied. In the next few days, the tropical wave approached Bermuda. But very early on 28 August and during the next few hours, the depression strengthened. A few hours later succeeded in the area of ​​low pressure to increase to the west of Bermuda short to a tropical storm. It got the name Jose. Jose began to slowly move north-northeast. It took only 27 hours to be Jose on August 29, again dissolved.

Hurricane Katia / hurricane (ex ) Katia

The eleventh named storm, Katia, the season was formed on August 29, south of the Cape Verde Islands and first moved rapidly westward across the tropical Atlantic. On August 30, the system intensified to a tropical storm and was named Katia. On September 1, Katia was upgraded to a hurricane. Due to very strong wind shear the hurricane lost strength and was downgraded during the day to a tropical storm. On September 2, Katia intensified into a hurricane again.

Katia then took a northerly course and eventually became distracted by an approaching trough to the northeast. Katia lost its tropical characteristics and arrived as a strong extratropical storm ( low ex - Katia ) on September 12 in Europe. He reached over the British Isles again hurricane strength ( to 158 km / h). The storm caused damage in the United Kingdom around 100 million pounds, and demanded a death toll. Even in the Baltic States and Russia led the far -attracting area of ​​low pressure with gusts to 90 km / h on the 15th of the month still to blackouts before it fell apart at the 17th in the White Sea region.

Unnamed tropical storm

As part of its follow-up analysis of the hurricane season, meteorologists of the National Hurricane Center classified a system that had formed on September 1 at 0:00 UTC clock about 370 kilometers north of Bermuda. It originated from a previously identified on the day of tropical disturbance that was classified at the beginning of September 1 as a tropical depression. Although the system was embedded in an area of ​​legitimate wind shear, it intensified rapidly into a tropical storm, was not named because in the operational this intensification was not noticed. The system reached early on September 2, its greatest intensity with winds of 75 km / h and transformed during the day to an extratropical system. This continued his trek continues in an east - north-easterly and then in an easterly direction, it weakened slowly. At the beginning of September 4 fell apart the rest of the system deep into a flat surface trough.

Tropical Storm Lee

The end of August produced a tropical wave in the western Caribbean Sea, scattered showers and thunderstorms. The system wander steadily west- northwestward, and the wave began to organize, as they had arrived in the south-east Gulf of Mexico. Late on September 1, presented Hurricane Hunters firmly on a flight into the system that a closed ground-level circulation was present, so the system was declared on September 2 at 0:00 UTC clock for Tropical Depression Thirteen. The depression moved to the north-west to has been upgraded throughout the day to Tropical Storm Lee. Lee organized further to reach its largest sustained wind speeds of 95 km / h early on September 3, when the center was located just south of the coast of Louisiana. On September 4, at 11:00 UTC clock, the center moved about 80 km southwest of Lavayette, Louisiana with sustained wind speeds of about 70 km / h over the country.

By Lee produced heavy rainfall resulted in the Parish Iberia, Terrebone, Plaquemines, St. Bernard, St. Tammany and Jefferson counties in Louisiana and Hancock, Harrison, Jackson and Stone in Mississippi to flash floods and floods. In New Orleans, Mayor Mitch Landrieu of the emergency alert was initiated before the arrival of the storm, fell after its details 250-320 mm rainfall. The 24 pumping stations to protect the lies largely below sea level New Orleans before the full run remained fully functional, unlike in 2005 when the passage of hurricane Katrina, the failure of pumping stations that caused parts of the city were several meters high flooded. In some areas at risk of flooding, the oil production was set as Vorkehrungsmaßnahme, numerous oil rigs in the Gulf of Mexico had been evacuated. The effects of the tropical storm caused the death of at least five people, including two people who burned in Texas in her trailer after foothills of the storm had fanned a bushfire. While Lee went through Louisiana, the storm weakened rapidly and early on September 5, the NHC issued its last warning. The remnant low moved slowly to the northeast and made in the next three days for extreme precipitation, especially in Pennsylvania, New York and the Canadian provinces of Quebec and Ontario caused flooding in the West.

Hurricane Maria

On 5 September, a low pressure area organized west of Africa. It became a tropical depression Fourteen. On the morning of 7 September, it has been updated to Tropical Storm Maria. In the tropical Atlantic disabled high wind shear their development, and Mary had almost resolved before September 9 began the convection and he built up again. The following day, favorable conditions began to appear, and the tropical cyclone became a Category 1 hurricane. On the afternoon of September 16, the storm lost tropical characteristics off the coast of Newfoundland. It made landfall and was at the southern tip of the Avalon Peninsula. It sparked fierce rain in the Newfoundland capital of St. John's.

As Katia previously pulled the Deep (ex -Maria ) on to Europe, as a powerful low over Iceland and Scandinavia, and disintegrated until the 25th of the month in the room of the White Sea.

Hurricane Nate

In the morning hours of September 6 thunderstorms were associated with a low pressure system that in the Bay of Campeche organization began to collect. The following day, the system won enough organization to be considered a tropical storm to be classified and named Nate. In a very slow train speed Nate began to strengthen. In the afternoon of September 8, Nate reached a peak of 120 km / h, ie a weak Category 1 hurricane. Because of cooler waters Nate began to weaken somewhat. On September 11, Nate made ​​landfall on the Mexican coast; as a weak tropical storm with a maximum wind speed of 65 km / h Shortly after making landfall, many of Nate's thunderstorms and rain bands broke up quickly, so that the rainfall was not as high as previously thought.

Hurricane Ophelia

Early September was a well-defined tropical wave off the African coast. The disturbance began collecting organization, so that it was the fifteenth tropical depression of the season on 21 September. It strengthened rapidly to a tropical storm Ophelia. Almost as soon as it became a tropical storm, began the vertical wind shear and had an impact on the system. Ophelia increased slowly in spite of the unfavorable conditions, reaching on 22 September wind speeds of 100 km / h The system weakened briefly to a minimal tropical storm off, and was on September 25, briefly extratropisch. On September 27, Ophelia again developed into a tropical depression, already reached on September 29, wind speeds of 110 km / h and was due to favorable conditions, a strong tropical storm. The next day, reinforced Ophelia into a Category 1 hurricane, and later to a Category 2 hurricane with winds of 165 km / h and an air pressure of 970 hPa Ophelia intensified rapidly and was already 6 hours later a severe hurricane category 3, the third season. It has been suggested that Ophelia would weaken again, but on October 1, Ophelia was unexpectedly east of Bermuda into a hurricane of category 4 Ophelia, however, could not be further aggravated. On October 2, Ophelia became weaker and weaker, so it was only a day later, still a tropical storm, and passed over Newfoundland. On October 3, Ophelia was extratropisch over Newfoundland. As some lows of the previous season was also ex - Ophelia in Europe weather determinative (Sturm to 100 km / h and snow in Scotland), and dissolve until around the 8th of October above the Polar Sea, Novaya Zemlya on the east yet.

Ophelia was 220 km / h and an air pressure of 940 hPa of the strongest Atlantic hurricane season of 2012.

Hurricane Philippe

On September 23, a well-defined tropical wave was located off the coast of Africa, in conjunction with plenty of thunderstorm activity. Changing position and embedded in a favorable environment for the development of the shaft quickly organized in the west. In the early hours of 24 September, it was identified as a tropical depression, while it was about 465 km south of the Cape Verde Islands. Later, the tropical depression to a tropical storm of the day was up graded and got the name " Philippe ". Philippe reached the next day maximum speeds of 95 km / h The system moved into western - northwestern direction and weakened as more and more so that it had only wind speeds of 65 km / h on September 28. But on October 1, Philippe strengthened and became a strong tropical storm with winds of 110 km / h After Philippe had been classified twelve days as a tropical storm, it has been incremented to a category 1 hurricane shortly on October 2, despite high wind shear. On October 6, Philippe strengthened again and became a major hurricane category 1 On 8 October, the hurricane weakened to a tropical storm. Several hours later, Philippe lost its tropical characteristics and was on 9 October extratropisch. With its duration of 17 days is the longest- Philippe Hurricane Bertha in July since 2008, which had a similar cyclone track as Philippe.

Hurricane Rina

The end of October convection began at the end of a cold front to show signs of organization. When they had formed in a low pressure area, it started north- northwest to pull in the direction and to organize further. In the afternoon it was then declared a Tropical Depression Eighteen. The storm experienced an intensification and was in the evening 23 October to Tropical Storm Rina. Rapide reinforced the storm on 24 October in a hurricane. 100 people have been killed by Rina in Central America to flooding. 27 people who were on a ship are missing. After a further strengthening of the system is upgraded to a Category 3 hurricane. Increasing wind shear and dry air but ensured that Rina weakens only to a category 1 hurricane and then a tropical storm. On October 27, Rina made ​​landfall on the east coast of the Yucatán and moved directly over the city of Cancun. The next day, Rina weakened in the Yucatánstraße into a tropical wave.

Tropical Storm Sean

In the first week of November has developed over the southern North Carolina is a non-tropical low pressure system that moved to the open Atlantic beyond and fell on its southeastern course over increasingly warmer water. The non- tropical system that already reached gale force southwest of Bermuda, slowly became more organized and was declared by the National Hurricane Center for Subtropical Storm Sean on November 8.

Shortly thereafter, the system began to take tropical characteristics and was classified three hours later as a tropical storm. The storm moved westward first, then went in a more northern and northeastern finally cyclone track. Sean erreichete on 9 and 10 November with winds of 100 km / h its peak intensity before he met stronger wind shear.

Early on November 12, Sean was a few hundred kilometers northeast of Bermuda absorbed by a cold front, which was consistent with an extra- tropical low pressure center over Newfoundland in conjunction.

Accumulated Cyclone Energy (ACE )

The adjacent table shows the ACE for each storm this year. The ACE describes the energy of a tropical storm by the strength of a storm is multiplied by the duration, that is, long -lasting storms and severe storms have a high ACE value. Traditionally, from the NOAA only storms with wind speeds of over 34 knots (63 km / h) recorded.

Course of the season

Storm names

The Atlantic hurricane season of 2011, the following names were used. This list will be used again in 2017, with the exception of the name Irene, which has been deleted by the World Meteorological Organization in the spring of 2012 from the list of names of tropical cyclones and replaced by Irma. This list is identical to the list for the Atlantic hurricane season of 2005, with the exception of the name of Don, Katia, Rina, Sean and Whitney, who Dennis, Katrina, Rita, Stan and Wilma replaced.

• Arlene
• Bret
• Cindy
• Don
• Emily
• Franklin
• Gert

• Harvey
• Irene
• Jose
• Katia
• Lee
• Mary
• Nate

• Ophelia
• Philippe
• Rina
• Sean
• Tammy (unused)
• Vince (unused)
• Whitney (unused)