The 2011 Atlantic hurricane season was one of the most active Atlantic hurricane seasons since 1851. The season started on June 1, 2011 and it ended on November 30, 2011. This season has been "above-average". This means that there has been a lot of tropical cyclones that have developed in the Atlantic basin. The season started when Tropical Storm Arlene formed on June 29. It formed in the Gulf of Mexico. It then made landfall on Veracruz. The storm killed 25 people. The amount of damage was $223 million (2011 USD). After Arlene dissipated, a lot of tropical storms began developing. Most of them developed from a frontal boundary. Which makes this season the first time to have the first eight named storms to have not reached hurricane status.

The record ended when Hurricane Irene formed in late August. Irene also became the first major hurricane (being a category three or higher on the Saffir–Simpson Hurricane Scale). After Irene dissipated, Hurricane Katia became the second major hurricane of the season. With seventeen tropical storms, only four became hurricanes. The following hurricane was Hurricane Rina. Between September 7-9, there were three tropical cyclones active, which were Katia, Maria and Nate. This information made the Climate Prediction Center issue a La Niña Advisory.

Season summary

Storms

Tropical Storm Arlene 

Tropical Storm Arlene formed off of a tropical wave. It moved across Central America. It brought a lot of rain and caused local flooding. Because of this, three people were killed. On June 27, the disturbance crossed the Yucatán Peninsula and into the Bay of Campeche. The storm began to develop over warm water. It was then given the name Arlene on June 29, around midnight. Arlene made landfall on Cabo Rojo with maximum sustained winds of 65 mph. It then died on July 1. About 22 people were killed while the storm passed through. Arlene cost over 2.6 billion pesos ($207.4 million) of damage.

Tropical Storm Bret 

Tropical Storm Bret formed off of a cold front. This front was near Florida. On July 16, a low-pressure area formed north of the Bahamas. It then began strengthening. The storm became tropical depression number 2 when it was near the Great Abaco Island. Within three hours, the storm was given the name Bret. Bret strengthen while it moved north-east. The storm began to weaken because of wind shear. It then died on July 22 with maximum sustained winds of 65 mph.

Tropical Storm Cindy 

Tropical Storm Cindy formed on July 20, when it developed into a tropical depression east of Bermuda. It then died two days later. It did not make landfall.

Tropical Storm Don 

Tropical Storm Don formed on July 27. It then made landfall as it weakened at Galveston, Texas. The storm did not help the drought the state of was in, dropping no more than  of an inch, which was lower than was forecasted.

Tropical Storm Emily 

Tropical Storm Emily formed on August 1. The storm made landfall as a remnant low in Haiti. It then strengthened while it passed through the Bahamas. When the storm left, it began to die.

Tropical Storm Franklin 

Tropical Storm Franklin formed on August 12. It did not make landfall. Bermuda was able to get some rain bands from the storm when it moved close by. The storm began to dissipate after it had left Bermuda.

Tropical Storm Gert 

Tropical Storm Gert formed on August 14. It did not make landfall. As Gert neared Bermuda, a small  eye-like feature became apparent on radar imagery. Coinciding with this, Gert reached its peak strength with winds of 60 mph (100 km/h).
Passing roughly 90 mi (150 km) east of Bermuda, Gert brought light rain and winds up to 25 mph (40 km/h) to the islands.
By August 16, convection associated with Gert had mostly dissipated and whether or not the system retained a closed surface low was ambiguous. As a result, Gert deteriorated into a post-tropical cyclone over the open Atlantic.

Tropical Storm Harvey 

Tropical Storm Harvey formed on August 18. Harvey made landfall in Belize. It was upgraded to Tropical Storm Harvey on August 19. By late August 19 the storm was strengthening rapidly and it was announced that it could become a hurricane just before landfall. However, it only strengthened a little bit. The storm then broke the Atlantic record for having eight tropical storms that did not become a hurricane. Harvey was then downgraded into a depression though it briefly regained tropical storm status in the Bay of Campeche. The storm then dissipated on August 22.

Hurricane Irene

Hurricane Irene formed on August 20. It became a hurricane while it passed through Puerto Rico. Irene then became the first hurricane of the season. Irene became a category 2 hurricane before reaching the Bahamas. It then strengthen into a major hurricane. Irene then became the first major hurricane of the season as well. Irene made landfall on Cape Lookout, North Carolina as a category 1 hurricane with 85 mph winds with an unusually low pressure for a category 1 hurricane. It then moved northeast. After weakening to a tropical storm, Irene made a second U.S. landfall at Brigantine Island in New Jersey at 5:35 a.m. The storm then moved northern and impacted New York City and New England. A total of 56 people were confirmed dead across the Caribbean, 10 U.S. states and Canada in the aftermath and damage from Hurricane Irene totaled $19 billion (2011 USD), making it the fifth costliest hurricane in the Atlantic basin. Irene then dissipated on August 29.

Tropical Depression Ten 

Tropical Depression Ten formed on August 25. It moved off the coast from Africa. It then began to move northeast. The storm dissipated the next day.

Tropical Storm Jose 

Tropical Storm Jose formed on August 27. Jose did not make any landfall.
Yet very early on August 28 and during the next few hours, the tropical wave partially strengthened as conditions for development slightly improved. However, early on August 28 – during the morning hours – the tropical wave nearly dissipated due to the high wind shear once again, this time generated by Hurricane Irene, after the tropical wave passed east to the south of Bermuda. But soon afterwards on August 28, the tropical wave managed to develop into Tropical Storm Jose, just to the west of Bermuda; Jose then began to move north-northeast, slowly. It lasted only 27 hours, as it dissipated on August 29.

Hurricane Katia 

The eleventh named storm of the season formed south of the Cape Verde Islands on August 29. The system became a tropical storm on August 30, at which time it was named Katia.
Hurricane Katia formed on August 29. It became the season's second hurricane early on September 1; however, its strength fluctuated until September 4 when it reached category 2 hurricane strength. On September 5 the system reached Category 3 (major hurricane status). Katia further strengthened into a Category 4 hurricane on September 5. It was downgraded to a category 1 storm by the end of the following day, and remained at that strength even as it became extra-tropical. The storm was of potential concern and was being monitored closely as it may have indirectly impacted the east coast of the United States and Canada. Warnings of severe weather were made for Northern Ireland and Scotland for the remnants of Katia. Its remnants struck the UK and the Republic of Ireland on September 11 and September 12, killing one. Its remnants caused blackouts as far east as Saint Petersburg.

Unnamed Tropical Storm 

The Unnamed Tropical Storm formed on September 1 east of Boston, Massachusetts as a tropical depression. The storm continued to strengthen and became a tropical storm later that day. It lost all of its tropical characteristics on September 2.

Tropical Storm Lee 
Tropical Storm Lee formed on September 1. It moved into the Gulf of Mexico. It made landfall in Lafayette, Louisiana as a minor tropical storm. It then moved northeastern before it dissipated on September 5.

Hurricane Maria 
Hurricane Maria formed on September 6. It moved close to Puerto Rico bringing a lot of rain to the island. Maria became a category 1 hurricane before it made landfall in Newfoundland. Maria then dissipated on September 16.

Hurricane Nate 
Hurricane Nate formed on September 7. Nate made landfall near the Mexican coastline. It dissipated on September 12.

Hurricane Ophelia 
Hurricane Ophelia formed on September 20. Ophelia then became a remnant low five days later. On September 27, the storm began to build strength. It then became a category 1 hurricane on September 30. On the same day, it became a category 2 hurricane. The next day, the storm became a category 3 hurricane. On October 1, the storm became a category 4 hurricane. After wards, the storm weakened quickly and lost its tropical features on October 3.

Hurricane Philippe 
Tropical Storm Philippe formed on September 24. It was a tropical storm for 12 days before becoming a category 1 hurricane on October 6. It weakened again to a tropical storm the next day and was no longer tropical on October 8.

Hurricane Rina 
Hurricane Rina formed on October 23 in the Caribbean Sea as a tropical depression. It began to strengthen quickly and became Tropical Storm Rina just hours later. On October 24, Rina reached Category 1 hurricane status. It was still strengthening quickly by October 25, with Rina becoming a category 2 hurricane in the morning hours. It later weakened again to a Category 1 hurricane, then a tropical storm. It continued to weaken, it then became a tropical depression (39 mph or less) on October 28. It became post-tropical (lost its tropical features) later that day.

Tropical Storm Sean
A large area of cloud that moved off North Carolina became Tropical Storm Sean with winds of 50 mph on November 8. The storm continued to strengthen and peaked at 65 mph. It dissipated on November 12 because of being merged with a cold front.

Storm names

Retirement 
In the spring of 2012, the WMO (World Meteorological Organization) has retired the name "Irene". The name "Irene" will never be used again in the Atlantic. "Irma" was chosen to replace that name.

References

Other websites 

 HPC rainfall page for 2011 Tropical Cyclones
 National Hurricane Center Website
 National Hurricane Center's Atlantic Tropical Weather Outlook
 Tropical Cyclone Formation Probability Guidance Product

Atlantic hurricane seasons
Atlantic hurricane season