2011 Atlantic hurricane season
Encyclopedia
The 2011 Atlantic hurricane season is tied for the third most active season
on record with 1887
, 1995
and 2010
. It began on June 1, 2011, and ended on November 30, 2011, however these dates conventionally delimit the period of each year when most tropical cyclones develop in the Atlantic basin. The season began with Arlene
, which developed on June 29 in the Gulf of Mexico, and made landfall near Veracruz
, causing 25 fatalities, and at least $223 million (2011 USD) in damage. After Arlene, the Atlantic basin featured a series of weak tropical systems, mainly forming off frontal boundaries
. Thus, for the first time since reliable records began in 1851, none of the first eight tropical storms attained hurricane strength. This streak ended when Hurricane Irene
, the first hurricane and major hurricane of the season, formed in late August. Shortly after Irene, Hurricane Katia
became the second major hurricane of the season. Despite the twenty tropical cyclones that have developed in the season, only seven storms have become hurricanes (all of them from late August onward), with the most recent being Hurricane Rina. There were three tropical cyclones active between September 7–9, consisting of Katia
, Maria
, and Nate
. It was then acknowledged in early September that La Niña
had returned, prompting a La Niña Advisory from the Climate Prediction Center
. In addition to the eighteen named storms, the National Hurricane Center identified a tropical storm that developed in early September near Bermuda that was not classified operationally.
Forecasts of hurricane activity
are issued before each hurricane season by noted hurricane experts Philip J. Klotzbach, William M. Gray
, and their associates at Colorado State University
; and separately by NOAA
forecasters.
Klotzbach's team (formerly led by Gray) defined the average number of storms per season (1950 to 2000) as 9.6 tropical storms, 5.9 hurricanes, 2.3 major hurricanes (storms reaching at least Category 3 strength in the Saffir-Simpson Hurricane Scale
) and ACE Index 96.1. NOAA
defines a season as above-normal, near-normal or below-normal by a combination of the number of named storms, the number reaching hurricane strength, the number reaching major hurricane strength and ACE Index
.
(ACE) value of approximately 165, citing that El Niño conditions were unlikely to develop by the start of the season. Lastly, the team noted a higher chance for storms to make landfall in the United States
than in 2010. In addition, Tropical Storm Risk (TSR), a public consortium
that comprises experts on insurance, risk management and seasonal climate forecasting at University College London
, issued an extended-range forecast a few days prior to that of CSU, with similar estimates for the year. In its report, TSR noted that tropical cyclone activity could be about 40% above the 1950–2010 average, with 15.6 (±4.3) tropical storms, 8.4 (±3.0) hurricanes, and 4.0 (±1.7) major hurricanes anticipated, and a cumulative ACE index of 141 (±58). On April 6, 2011, the CSU team slightly revised their December forecast, predicting 16 named storms, nine hurricanes, and five major hurricanes.
On May 19, 2011, the Climate Prediction Center
issued NOAA
's outlook for the Atlantic hurricane season. The CPC expected that 12–18 named storms, 6–10 hurricanes, and 3–6 major hurricanes would form in the Atlantic during 2011. The center cited above-normal sea surface temperature
s, a weakening La Niña
, and the effect of the warm regime of the Atlantic multidecadal oscillation
as the basis behind their forecast, adding that seasonal climate models hint that "activity comparable to some of the active seasons since 1995" could occur. On May 26, the UK Met Office
(UKMO) issued a forecast of a slightly above-average season. They predicted 13 tropical storms with a 70% chance that the number would be between 10 and 17. However, they do not issue forecasts on the number of hurricanes and major hurricanes. They also predicted an ACE Index
of 151 with a 70% chance that the index would be in the range 89 to 212.
of 163. No prediction for the number of major hurricanes was made.
that tracked westward across the Caribbean Sea
in late June. It proceeded toward the west-northwest along Central America
, bringing heavy rainfall to the area that caused flooding and killed three people. By June 27, the disturbance had crossed the Yucatán Peninsula
and emerged into the Bay of Campeche
. Despite moderate wind shear
, it organized over warm waters and was designated as Tropical Storm Arlene at midnight June 29 about 280 mi (450 km) south-southeast of Tampico, Tamaulipas.
As it continued to strengthen, Arlene began to move to the west along a ridge
to its north and northwest. Although forecast models supported intensification to hurricane status, the storm attained a peak intensity of only 65 mph (100 km/h). Arlene moved ashore near Cabo Rojo
as a strong tropical storm around 0900 UTC June 30. Turning west-southwestward, the storm began to weaken as it decreased in organization. On July 1, Arlene was downgraded to a tropical depression just before dissipating over the Sierra Madre Mountains
; however, rainfall and gusty winds continued to affect portions of Mexico. Arlene's impact resulted in damaging floods and mudslides throughout the country, as well as a total of 22 confirmed deaths. Across the state of Hidalgo, damage from the storm reached 2.6 billion pesos
($207.4 million).
extended westward over the North Atlantic, as its westernmost component remained stationary near Florida
. On July 16, a low-pressure area developed to the north of the Bahamas along the weakening boundary; it became better organized under abating shear conditions
. A closed circulation center formed, and the next day at 2100 UTC, the NHC issued the formation of Tropical Depression Two about 100 mi (160 km) northwest of Great Abaco Island
. It strengthened into Tropical Storm Bret just three hours after formation. Moving little, Bret continued to strengthen as thunderstorms intensified around the center. The storm developed an eye-like feature
on July 18, indicating peak surface winds of around 65 mph (100 km/h) before it began to accelerate northeastward. Although strong wind shear and dry inhibited further development, Bret maintained a well-defined circulation for the next couple of days, with patches of persistent thunderstorms. However, its center remained exposed, causing it weaken to a tropical depression early on July 22. Despite very hostile wind shear conditions, Bret retained tropical cyclone status for several hours prior to dissipating about 375 mi (605 km) north of Bermuda
.
, the depression moved northeast and maintained this general direction for the remainder of its existence. Hours later, the system strengthened into Tropical Storm Cindy. Convection steadily increased over the storm and a ragged eye-like
featured appeared on both visible and microwave satellite imagery. Corresponding with this, Cindy attained its peak intensity just below hurricane status late on July 21 with winds of 70 mph (110 km/h) and a barometric pressure of 994 mbar (hPa; 29.35 inHg). Shortly thereafter, the storm moved over waters cooler than 78.8 °F (26 °C). Throughout July 22, convection diminished and Cindy transitioned into a post-tropical cyclone about 985 mi (1,585 km) southwest of Ireland
. The remnants persisted for another 12 hours before degenerating into a trough over the North Atlantic.
flight observed gale force winds and a broad circulation, which prompted the National Hurricane Center to initiate advisories on Tropical Storm Don on July 27. After the storm was named, officials in Texas
began making preparations for Don. The University of Texas Medical Branch
in Galveston
issued a level one alert for Don, and city officials began preparing for a possible evacuation. The NHC later downgraded Don into a tropical depression then a remnant low after it quickly disintegrated upon making landfall and hitting the dry air over Texas as a result of the state's extreme drought, dropping much less than the forecasted rainfall at no more than 2/3 of an inch along the coast.
's southeastern coast, as it slowly strengthened. Later, on August 6, Emily regenerated into a weak depression, dissipating again the next day. The remnants of Emily tracked east-northeastward toward Bermuda. Soon afterwards, Emily's remnants took an eastward turn, and moved towards the open Atlantic. On August 10, convection significantly re-developed in the middle of the Atlantic Ocean, and the National Hurricane Center assessed the system as having a 10% chance of regeneration into a tropical cyclone.
. Although well to the north of Bermuda, the system brought unsettled weather to the archipelago, with rainfall reaching 0.07 in (1.8 mm) at L.F. Wade International Airport.
Maintaining a northeasterly track, the depression intensified into Tropical Storm Franklin early on August 13 following a large burst of convection over its center. Later that morning, Franklin attained its peak winds of 45 mph (75 km/h) before encountering increasing wind shear
and decreasing sea surface temperatures. Rapid deterioration of the storm's structure took place as environmental conditions became increasingly hostile for tropical cyclones. Convection was sheared more than 100 mi (155 km) from the center of circulation and Franklin began acquiring characteristics of an extratropical cyclone
. Early on August 14, Franklin quickly completed its transition into an extratropical system, prompting the final advisory from the NHC.
, became associated with a synoptic-scale
trough. Dropping west-southwestward, it interacted with an upper low to produce an area of disorganized convection, and by then the NHC began to monitor the system. By August 13, the small low had become very well-defined, with a tight wind circulation center and deep convection; it was designated as a tropical depression at 0300 UTC that day, about 360 mi (580 km) south-southeast of Bermuda. As the depression re-curved west-northwestward along the weakening subtropical ridge
, it intensified into Tropical Storm Gert, due to light wind shear and moist air, about 15 hours after its formation. As Gert neared Bermuda, a small 7 to 9 mi (11.3 to 14.5 km) eye-like feature
became apparent on radar imagery
. Coinciding with this, Gert reached its peak intensity with winds of 65 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 degenerated into a post-tropical cyclone over the open Atlantic.
entered the Caribbean Sea. It eventually gained enough organization to be classified as Tropical Depression Eight on August 18. It was upgraded to Tropical Storm Harvey on August 19. By late August 19 the storm was intensifying rapidly and it was announced that it could become a hurricane just before landfall. However, by Saturday afternoon, August 20, Harvey made landfall, never having reached hurricane strength, resetting the Atlantic record as the first eight named storms of the season did not reach hurricane strength. Harvey was then downgraded into a depression and it dissipated on August 22.
which weakened it slightly, but caused its wind field to greatly expand. On August 26, New York
mayor Michael Bloomberg
told coastal residents to 'get moving, now.' The next day, Irene made landfall on Cape Lookout, North Carolina as a category 1 hurricane with 85 mph winds and unusually low pressure for a category 1 hurricane. Hurricane Irene made a second U.S. landfall at Little Egg Inlet in New Jersey at 5:35 a.m., making it the first landfalling hurricane in 108 years for New Jersey. On August 28, Irene was downgraded to a tropical storm as it made its third U.S. landfall in the Coney Island
area of Brooklyn, New York, at approximately 9:00 a.m. on August 28. Irene became a post-tropical storm over Quebec
and Atlantic Canada
on August 29.
Forming on August 20, Irene was the second earliest ninth Atlantic tropical cyclone on record, along with an unnamed tropical storm from the 1936 season
. At least 55 people were confirmed dead across the Caribbean, 10 U.S. states and Canada in the aftermath and damage from Hurricane Irene totaled $10.1 billion (2011 USD).
exited the west coast of Africa
. During the first few days, the tropical wave produced convection, as it slowly moved westward, and became associated with an area of low pressure. But by the next week, the wave dissipated to a weak area of low pressure – due to high wind shear – as it began to move northwestward, while fluctuating slightly in intensity. In the next few days, the tropical wave approached Bermuda
; while remaining disorganized, and weakening even further. 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.
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
.
. At 4 a.m. CDT September 4, Lee made landfall roughly 50 miles (80.5 km) to the southwest of Lafayette, Louisiana
with maximum sustained winds of 45 mph (75 km/h). Further weakening occurred as Lee moved across Louisiana, and the last NHC advisory on Lee was issued early on September 5, while its remnants proceeded to wreak havoc (mainly flooding) over the following two to three days northward into Pennsylvania, New York State and Canada (Quebec
and Ontario
).
with winds recorded at 64 mph (103 km/h). The capital city of St. John's
experienced heavy rain and gale-force winds, but not as severe as anticipated.
oil rigs not available operationally. Due to the storm's slow movement, Nate began to upwell cooler waters in its wake, resulting in weakening. Additionally, very dry air began getting entrained into the system. On September 11, Nate made landfall on the Mexican coastline as a weak tropical storm, with maximum sustained winds of 45 mph (75 km/h). Shortly after making landfall, much of Nate's showers and thunderstorms dissipated, and thus rainfall totals were not as high as expected.
began impacting the system. Ophelia slowly strengthened despite the unfavorable conditions and attained winds of 65 mph (100 km/h) on September 22. The system briefly weakened to a minimal tropical storm before strengthening again. However, because of the extremely strong wind shear, Ophelia was ripped apart and dissipated into a post-tropical remnant low on September 25.
Wind shear remained strong, but not as strong as before. Thus, during the afternoon hours of September 27, Ophelia was able to develop convection near its center, and was designated a tropical depression. Ophelia gradually strengthened further into a tropical storm as it passed to the north of the Caribbean
. In Dominica
, heavy rains from the storm caused widespread flooding. During the afternoon hours of September 29, despite the relatively unfavorable environment, Ophelia strengthened into a Category 1 hurricane. As wind shear relaxed, early on September 30, Ophelia rapidly intensified
and became a Category 2 hurricane. Later that day, Ophelia further strengthened into a Category 3 hurricane, becoming the third major hurricane of the season. The eye of Ophelia passed directly over a NOAA buoy
early on October 1, which reported sustained winds of 96 mph (155 km/h) and a pressure of 952 mbar (28.11 inHg). The intensification trend continued, and Ophelia strengthened further to a Category 4 hurricane late that day east of Bermuda
. Through the following day (Sunday), increasing southwesterly wind shear and cooler water temperatures combined to cause Ophelia to progressively weaken back into a Category 1 hurricane by evening and weakened to a tropical storm during the morning hours of October 3. Several hours later, Ophelia was declared as a post-tropical cyclone soon after making landfall on the Avalon Peninsula
in Newfoundland.
emerged off the coast of Africa, associated with plentiful shower and thunderstorm activity
. Moving westward and embedded within a favorable environment for development, the wave quickly became organized. During the morning hours of September 24, the National Hurricane Center designated the low as a tropical depression, while located about 290 mi (465 km) south of the southernmost Cape Verde Islands. Later that day, the depression was upgraded to a tropical storm, designated "Philippe". Since that time strong shear from both upper level winds and later on from Ophelia's outflow, as well as periodic entrainment of dry air kept the cyclone both small and disorganized, with the center often exposed to the point where the low level circulation reformed under the convection that defines a tropical system at least once. An exposed cyclone can be seen as a wispy series of clouds circling a small area, rather than under the canopy of thunderstorms. Because of this hostile environment, Philippe remained near the minimum for a tropical storm. On the afternoon of October 2, an Advanced Scatterometer (ASCAT)
pass confirmed that Philippe was a strong tropical storm, contrary to satellite estimates. Despite high wind shear, it remained a strong tropical storm afterward and actually at times developed an eye
feature. On October 6, after over 12 days as a tropical storm, Philippe became a strong Category 1 hurricane. On October 8, Philippe weakened to a tropical storm, then became post-tropical hours later, on October 9.
moved into the western Caribbean. The front, in conjunction with east-southeasterly trade winds, produced a broad area of cyclonic circulation over the southwestern Caribbean. Moving slowly towards the north and northwest, barometric pressures in the area began falling, and the disturbance was expected to move into an environment more conducive for development. Thus, the National Hurricane Center gave the disturbance a medium chance, 30%, of developing into a tropical cyclone within 48 hours. Further organization occurred during the afternoon hours of October 21, as the low pressure area became more consolidated. However, the following day, the disturbance became slightly less organized, depicted by a decrease in tropical cyclone formation probabilities.
On October 23, a reconnaissance aircraft
flew into the disturbance, finding a well-defined center of circulation. This, combined with satellite imagery
, led to the formation of Tropical Depression Eighteen during the evening hours of that day; it strengthened to a tropical storm just several hours later, and earned the name "Rina". Moving towards the north-northwest, Rina rapidly intensified
on October 24, becoming a hurricane just 21 hours after formation. Further strengthening commenced for the remaining of the day, although Rina did not reach peak intensity until the evening hours of October 25. Shortly thereafter, the increase of wind shear and dry air led to weakening the following day, and Rina weakened to a tropical storm early on October 27. Scraping the Yucatan Peninsula, Rina brought heavy rainfall and gusty winds before turning towards the north. Early the next day, Rina weakened into a tropical depression, and during the afternoon hours, further dissipated into a remnant low.
. On November 6, the National Hurricane Center began monitoring a non-tropical area of low pressure producing a large area of gale force winds to the southwest of Bermuda. Moving towards the south and southeast, the low pressure area began to enter higher Sea Surface Temperatures and subsequently became better organized. By the early morning hours of November 8, the low had become sufficiently organized to be declared as a subtropical storm, and then a fully tropical storm several hours later. Sean strengthened to attain a peak intensity of 65 mph (100 km/h) on November 9 and 10 before it began to enter an area of higher wind shear. Early on November 12, Sean was absorbed by a cold front, associated with a powerful extratropical cyclone centered over Newfoundland
, while Sean was located several hundred miles to the northeast of Bermuda.
with the exception of Don, Katia, Rina, Sean, and Whitney, which replaced Dennis
, Katrina
, Rita
, Stan
, and Wilma
, respectively. The names Don, Katia, Rina, and Sean were used for the first time in the Atlantic Basin. Retired names, if any, will be announced by the World Meteorological Organization
in the spring of 2012. The names not retired from this list will be used again in the 2017 season.
for each storm in the season. Broadly speaking, the ACE is a measure of the power of a 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 calculated for only full advisories on specifically tropical systems reaching or exceeding wind speeds of 34 knots (39 mph, 63 km/h), or tropical storm strength. Accordingly, tropical depressions are not included here. The ACE also does not include subtropical storms, therefore values accrued while Sean was subtropical are not calculated in its ACE. Later the NHC reexamines the data, and produces a final report on each storm, which can lead to the ACE for a storm being revised either upward or downward. Until the final reports are issued, ACEs are, therefore, provisional.
Atlantic hurricane season
The Atlantic hurricane season is the period in a year when hurricanes usually form in the Atlantic Ocean. Tropical cyclones in the North Atlantic are called hurricanes, tropical storms, or tropical depressions. In addition, there have been several storms over the years that have not been fully...
on record with 1887
1887 Atlantic hurricane season
Another May storm formed south of Jamaica on May 17, way outside of the season and moved generally northward. It crossed Cuba on the 19th as a tropical storm, and moved out to sea. Two peaked at twice, once on May 18 and May 20. Two dissipated on the 21st in the Atlantic Ocean...
, 1995
1995 Atlantic hurricane season
The 1995 Atlantic hurricane season was the third most active Atlantic hurricane season on record. It officially began on June 1, 1995, and lasted until November 30, 1995. These dates conventionally delimit the period of each year when most tropical cyclones form in the north Atlantic ocean...
and 2010
2010 Atlantic hurricane season
The 2010 Atlantic hurricane season was the third most active Atlantic hurricane season on record, tying with the 1887 Atlantic hurricane season, 1995 Atlantic hurricane season and the 2011 Atlantic hurricane season. It had the most number of named storms since the 2005 season and also ties with the...
. It began on June 1, 2011, and ended on November 30, 2011, however these dates conventionally delimit the period of each year when most tropical cyclones develop in the Atlantic basin. The season began with Arlene
Tropical Storm Arlene (2011)
Tropical Storm Arlene was a strong tropical storm that affected much of eastern Mexico, as well as the first tropical cyclone to form during the 2011 Atlantic hurricane season. Originating from an Atlantic tropical wave, the precursor disturbance crossed the Yucatán Peninsula before emerging into...
, which developed on June 29 in the Gulf of Mexico, and made landfall near Veracruz
Veracruz
Veracruz, formally Veracruz de Ignacio de la Llave officially Estado Libre y Soberano de Veracruz de Ignacio de la Llave , is one of the 31 states that, along with the Federal District, comprise the 32 federative entities of Mexico. It is divided in 212 municipalities and its capital city is...
, causing 25 fatalities, and at least $223 million (2011 USD) in damage. After Arlene, the Atlantic basin featured a series of weak tropical systems, mainly forming off frontal boundaries
Weather front
A weather front is a boundary separating two masses of air of different densities, and is the principal cause of meteorological phenomena. In surface weather analyses, fronts are depicted using various colored lines and symbols, depending on the type of front...
. Thus, for the first time since reliable records began in 1851, none of the first eight tropical storms attained hurricane strength. This streak ended when Hurricane Irene
Hurricane Irene (2011)
Hurricane Irene was a large and powerful Atlantic hurricane that left extensive flood and wind damage along its path through the Caribbean, the United States East Coast and as far north as Atlantic Canada in 2011...
, the first hurricane and major hurricane of the season, formed in late August. Shortly after Irene, Hurricane Katia
Hurricane Katia (2011)
Hurricane Katia was the eleventh named storm, second hurricane and second major hurricane of the 2011 Atlantic hurricane season. A Cape Verde-type hurricane, Katia developed from a tropical wave south of the Cape Verde Islands on August 29. Tracking west-northwestward, the system gradually...
became the second major hurricane of the season. Despite the twenty tropical cyclones that have developed in the season, only seven storms have become hurricanes (all of them from late August onward), with the most recent being Hurricane Rina. There were three tropical cyclones active between September 7–9, consisting of Katia
Hurricane Katia (2011)
Hurricane Katia was the eleventh named storm, second hurricane and second major hurricane of the 2011 Atlantic hurricane season. A Cape Verde-type hurricane, Katia developed from a tropical wave south of the Cape Verde Islands on August 29. Tracking west-northwestward, the system gradually...
, Maria
Hurricane Maria (2011)
Hurricane Maria was the thirteenth named storm and third hurricane of the 2011 Atlantic hurricane season. Maria developed from a strong tropical wave that moved off the coast of Africa in early September. Moving westward, the wave organized rapidly, and became a tropical storm on September 6...
, and Nate
Hurricane Nate (2011)
Hurricane Nate was an Atlantic hurricane that made landfall on the Gulf Coast of Mexico in early September. The sixteenth named storm and fourth hurricane of the 2011 Atlantic hurricane season, Hurricane Nate formed in the Bay of Campeche on September 7 and initially moved erratically...
. It was then acknowledged in early September that La Niña
La Niña
La Niña is a coupled ocean-atmosphere phenomenon that is the counterpart of El Niño as part of the broader El Niño-Southern Oscillation climate pattern. During a period of La Niña, the sea surface temperature across the equatorial Eastern Central Pacific Ocean will be lower than normal by 3–5 °C...
had returned, prompting a La Niña Advisory from the Climate Prediction Center
Climate Prediction Center
The Climate Prediction Center is one of the National Centers for Environmental Prediction, which are a part of NOAA's National Weather Service. It is located in Camp Springs, Maryland.-Products:...
. In addition to the eighteen named storms, the National Hurricane Center identified a tropical storm that developed in early September near Bermuda that was not classified operationally.
Seasonal forecasts
| Source | Date | Named storms |
Hurricanes | Major hurricanes |
|
| Average (1950–2000) | 9.6 | 5.9 | 2.3 | ||
| Record high activity | 28 2005 Atlantic hurricane season The 2005 Atlantic hurricane season was the most active Atlantic hurricane season in recorded history, repeatedly shattering numerous records. The impact of the season was widespread and ruinous with an estimated 3,913 deaths and record damage of about $159.2 billion... |
15 2005 Atlantic hurricane season The 2005 Atlantic hurricane season was the most active Atlantic hurricane season in recorded history, repeatedly shattering numerous records. The impact of the season was widespread and ruinous with an estimated 3,913 deaths and record damage of about $159.2 billion... |
8 1950 Atlantic hurricane season The 1950 Atlantic hurricane season was the first year in which tropical cyclones were given official names in the Atlantic basin. Names were taken from the Joint Army/Navy Phonetic Alphabet, with the first named storm being designated "Able", the second "Baker", and so on. It was an active season... |
||
| Record low activity | 4 1983 Atlantic hurricane season The 1983 Atlantic hurricane season was the least active Atlantic hurricane season in 53 years, with only four tropical storms forming. The season officially began on June 1, 1983, and lasted until November 30, 1983. These dates conventionally delimit the period of each year when most storms... |
2 1982 Atlantic hurricane season The 1982 Atlantic hurricane season officially began on June 1, 1982 and lasted until November 30, 1982, and was a below average season. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin... |
0 1994 Atlantic hurricane season The 1994 Atlantic hurricane seasonofficially began June 1, 1994, and officially ended November 30, 1994. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin.... † |
||
| ––––––––––––––––––––––––––––––––––––––––––––––––––––––– | |||||
| TSR | December 6, 2010 | 11–20 | 5–11 | 2–6 | |
| CSU Colorado State University Colorado State University is a public research university located in Fort Collins, Colorado. The university is the state's land grant university, and the flagship university of the Colorado State University System.The enrollment is approximately 29,932 students, including resident and... |
December 8, 2010 | 17 | 9 | 5 | |
| TSR | April 4, 2011 | 10–18 | 5–10 | 2–5 | |
| CSU | April 6, 2011 | 16 | 9 | 5 | |
| NOAA National Oceanic and Atmospheric Administration The National Oceanic and Atmospheric Administration , pronounced , like "noah", is a scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere... |
May 19, 2011 | 12–18 | 6–10 | 3–6 | |
| TSR | May 24, 2011 | 10–18 | 5–10 | 2–5 | |
| UKMO | May 26, 2011 | 13 | N/A | N/A | |
| CSU | June 1, 2011 | 16 | 9 | 5 | |
| FSU COAPS | June 1, 2011 | 17 | 9 | N/A | |
| WSI | July 26, 2011 | 15 | 8 | 4 | |
| CSU | August 3, 2011 | 16 | 9 | 5 | |
| NOAA | August 4, 2011 | 14–19 | 7–10 | 3–5 | |
| WSI | September 21, 2011 | 21 | 7 | 4 | |
| ––––––––––––––––––––––––––––––––––––––––––––––––––––––– | |||||
| 19 | 7 | 3 | |||
| *† Most recent of several such occurrences. (See all) | |||||
Forecasts of hurricane activity
Tropical cyclone seasonal forecasting
Tropical cyclone seasonal forecasting is the process of predicting the number of tropical cyclones in one of the world's seven tropical cyclone basins during a particular tropical cyclone season. In the north Atlantic Ocean, one of the most widely publicized annual predictions comes from the...
are issued before each hurricane season by noted hurricane experts Philip J. Klotzbach, William M. Gray
William M. Gray
William M. "Bill" Gray is Emeritus Professor of Atmospheric Science at Colorado State University , and head of the Tropical Meteorology Project at CSU's Department of Atmospheric Sciences. He is a pioneer in the science of forecasting hurricanes and one of the world's leading experts on tropical...
, and their associates at Colorado State University
Colorado State University
Colorado State University is a public research university located in Fort Collins, Colorado. The university is the state's land grant university, and the flagship university of the Colorado State University System.The enrollment is approximately 29,932 students, including resident and...
; and separately by NOAA
National Oceanic and Atmospheric Administration
The National Oceanic and Atmospheric Administration , pronounced , like "noah", is a scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere...
forecasters.
Klotzbach's team (formerly led by Gray) defined the average number of storms per season (1950 to 2000) as 9.6 tropical storms, 5.9 hurricanes, 2.3 major hurricanes (storms reaching at least Category 3 strength in the Saffir-Simpson Hurricane Scale
Saffir-Simpson Hurricane Scale
The Saffir–Simpson Hurricane Scale , or the Saffir–Simpson Hurricane Wind Scale , classifies hurricanes — Western Hemisphere tropical cyclones that exceed the intensities of tropical depressions and tropical storms — into five categories distinguished by the intensities of their sustained winds...
) and ACE Index 96.1. NOAA
National Oceanic and Atmospheric Administration
The National Oceanic and Atmospheric Administration , pronounced , like "noah", is a scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere...
defines a season as above-normal, near-normal or below-normal by a combination of the number of named storms, the number reaching hurricane strength, the number reaching major hurricane strength and ACE Index
Accumulated cyclone energy
Accumulated cyclone energy is a measure used by the National Oceanic and Atmospheric Administration to express the activity of individual tropical cyclones and entire tropical cyclone seasons, particularly the North Atlantic hurricane season. It uses an approximation of the energy used by a...
.
Pre-season forecasts
On December 8, 2010, Klotzbach's CSU team issued its first extended-range forecast for the 2011 season, predicting well above-average activity with 17 named storms, nine hurricanes, and five major hurricanes. In addition, the team expected an accumulated cyclone energyAccumulated cyclone energy
Accumulated cyclone energy is a measure used by the National Oceanic and Atmospheric Administration to express the activity of individual tropical cyclones and entire tropical cyclone seasons, particularly the North Atlantic hurricane season. It uses an approximation of the energy used by a...
(ACE) value of approximately 165, citing that El Niño conditions were unlikely to develop by the start of the season. Lastly, the team noted a higher chance for storms to make landfall in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
than in 2010. In addition, Tropical Storm Risk (TSR), a public consortium
Consortium
A consortium is an association of two or more individuals, companies, organizations or governments with the objective of participating in a common activity or pooling their resources for achieving a common goal....
that comprises experts on insurance, risk management and seasonal climate forecasting at University College London
University College London
University College London is a public research university located in London, United Kingdom and the oldest and largest constituent college of the federal University of London...
, issued an extended-range forecast a few days prior to that of CSU, with similar estimates for the year. In its report, TSR noted that tropical cyclone activity could be about 40% above the 1950–2010 average, with 15.6 (±4.3) tropical storms, 8.4 (±3.0) hurricanes, and 4.0 (±1.7) major hurricanes anticipated, and a cumulative ACE index of 141 (±58). On April 6, 2011, the CSU team slightly revised their December forecast, predicting 16 named storms, nine hurricanes, and five major hurricanes.
On May 19, 2011, the Climate Prediction Center
Climate Prediction Center
The Climate Prediction Center is one of the National Centers for Environmental Prediction, which are a part of NOAA's National Weather Service. It is located in Camp Springs, Maryland.-Products:...
issued NOAA
National Oceanic and Atmospheric Administration
The National Oceanic and Atmospheric Administration , pronounced , like "noah", is a scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere...
's outlook for the Atlantic hurricane season. The CPC expected that 12–18 named storms, 6–10 hurricanes, and 3–6 major hurricanes would form in the Atlantic during 2011. The center cited above-normal sea surface temperature
Sea surface temperature
Sea surface temperature is the water temperature close to the oceans surface. The exact meaning of surface varies according to the measurement method used, but it is between and below the sea surface. Air masses in the Earth's atmosphere are highly modified by sea surface temperatures within a...
s, a weakening La Niña
La Niña
La Niña is a coupled ocean-atmosphere phenomenon that is the counterpart of El Niño as part of the broader El Niño-Southern Oscillation climate pattern. During a period of La Niña, the sea surface temperature across the equatorial Eastern Central Pacific Ocean will be lower than normal by 3–5 °C...
, and the effect of the warm regime of the Atlantic multidecadal oscillation
Atlantic Multidecadal Oscillation
The Atlantic multidecadal oscillation is a mode of variability occurring in the North Atlantic Ocean and which has its principal expression in the sea surface temperature field...
as the basis behind their forecast, adding that seasonal climate models hint that "activity comparable to some of the active seasons since 1995" could occur. On May 26, the UK Met Office
Met Office
The Met Office , is the United Kingdom's national weather service, and a trading fund of the Department for Business, Innovation and Skills...
(UKMO) issued a forecast of a slightly above-average season. They predicted 13 tropical storms with a 70% chance that the number would be between 10 and 17. However, they do not issue forecasts on the number of hurricanes and major hurricanes. They also predicted an ACE Index
Accumulated cyclone energy
Accumulated cyclone energy is a measure used by the National Oceanic and Atmospheric Administration to express the activity of individual tropical cyclones and entire tropical cyclone seasons, particularly the North Atlantic hurricane season. It uses an approximation of the energy used by a...
of 151 with a 70% chance that the index would be in the range 89 to 212.
Mid-season forecasts
On June 1, CSU released their mid-season predictions, with numbers unchanged from those published in April. Concurrently, the Florida State University Center for Ocean-Atmospheric Prediction Studies (FSU COAPS) issued its third annual Atlantic hurricane season forecast, predicting seventeen named storms, nine hurricanes, and an ACE IndexAccumulated cyclone energy
Accumulated cyclone energy is a measure used by the National Oceanic and Atmospheric Administration to express the activity of individual tropical cyclones and entire tropical cyclone seasons, particularly the North Atlantic hurricane season. It uses an approximation of the energy used by a...
of 163. No prediction for the number of major hurricanes was made.
Tropical Storm Arlene
The origins of Tropical Storm Arlene trace back to a tropical waveTropical wave
Tropical waves, easterly waves, or tropical easterly waves, also known as African easterly waves in the Atlantic region, are a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, which move from east to west across the tropics causing areas of...
that tracked westward across the Caribbean Sea
Caribbean Sea
The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles, and to the east by the Lesser Antilles....
in late June. It proceeded toward the west-northwest along Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
, bringing heavy rainfall to the area that caused flooding and killed three people. By June 27, the disturbance had crossed the Yucatán Peninsula
Yucatán Peninsula
The Yucatán Peninsula, in southeastern Mexico, separates the Caribbean Sea from the Gulf of Mexico, with the northern coastline on the Yucatán Channel...
and emerged into the Bay of Campeche
Bay of Campeche
The Bay of Campeche is the southern bight of the Gulf of Mexico. It is surrounded on three sides by the Mexican states of Campeche, Tabasco and Veracruz. It was named by Francisco Hernández de Córdoba and Antonio de Alaminos during their expedition in 1517...
. Despite moderate wind shear
Wind shear
Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere...
, it organized over warm waters and was designated as Tropical Storm Arlene at midnight June 29 about 280 mi (450 km) south-southeast of Tampico, Tamaulipas.
As it continued to strengthen, Arlene began to move to the west along a ridge
Ridge (meteorology)
A ridge is an elongated region of relatively high atmospheric pressure, the opposite of a trough....
to its north and northwest. Although forecast models supported intensification to hurricane status, the storm attained a peak intensity of only 65 mph (100 km/h). Arlene moved ashore near Cabo Rojo
Cabo Rojo (Mexico)
Cabo Rojo is a barrier of quartzite sand deposited adjacent to the coast of the Mexican state of Veracruz, about south of the city of Tampico, Tamaulipas. It encloses the brackish lagoon called Laguna de Tamiahua...
as a strong tropical storm around 0900 UTC June 30. Turning west-southwestward, the storm began to weaken as it decreased in organization. On July 1, Arlene was downgraded to a tropical depression just before dissipating over the Sierra Madre Mountains
Sierra Madre Oriental
The Sierra Madre Oriental is a mountain range in northeastern Mexico.-Setting:Spanning the Sierra Madre Oriental runs from Coahuila south through Nuevo León, southwest Tamaulipas, San Luis Potosí, Querétaro, and Hidalgo to northern Puebla, where it joins with the east-west running Eje Volcánico...
; however, rainfall and gusty winds continued to affect portions of Mexico. Arlene's impact resulted in damaging floods and mudslides throughout the country, as well as a total of 22 confirmed deaths. Across the state of Hidalgo, damage from the storm reached 2.6 billion pesos
Mexican peso
The peso is the currency of Mexico. Modern peso and dollar currencies have a common origin in the 15th–19th century Spanish dollar, most continuing to use its sign, "$". The Mexican peso is the 12th most traded currency in the world, the third most traded in the Americas, and by far the most...
($207.4 million).
Tropical Storm Bret
In mid July, a cold frontCold front
A cold front is defined as the leading edge of a cooler mass of air, replacing a warmer mass of air.-Development of cold front:The cooler and denser air wedges under the less-dense warmer air, lifting it...
extended westward over the North Atlantic, as its westernmost component remained stationary near Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
. On July 16, a low-pressure area developed to the north of the Bahamas along the weakening boundary; it became better organized under abating shear conditions
Wind shear
Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere...
. A closed circulation center formed, and the next day at 2100 UTC, the NHC issued the formation of Tropical Depression Two about 100 mi (160 km) northwest of Great Abaco Island
Abaco Islands
The Abaco Islands lie in the northern Bahamas and comprise the main islands of Great Abaco and Little Abaco, together with the smaller Wood Cay, Elbow Cay, Lubbers Quarters Cay, Green Turtle Cay, Great Guana Cay, Castaway Cay, Man-o-War Cay, Stranger's Cay, Umbrella Cay, Walker's Cay, Little Grand...
. It strengthened into Tropical Storm Bret just three hours after formation. Moving little, Bret continued to strengthen as thunderstorms intensified around the center. The storm developed an eye-like feature
Eye (cyclone)
The eye is a region of mostly calm weather found at the center of strong tropical cyclones. The eye of a storm is a roughly circular area and typically 30–65 km in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the second most severe weather of a cyclone...
on July 18, indicating peak surface winds of around 65 mph (100 km/h) before it began to accelerate northeastward. Although strong wind shear and dry inhibited further development, Bret maintained a well-defined circulation for the next couple of days, with patches of persistent thunderstorms. However, its center remained exposed, causing it weaken to a tropical depression early on July 22. Despite very hostile wind shear conditions, Bret retained tropical cyclone status for several hours prior to dissipating about 375 mi (605 km) north of Bermuda
Bermuda
Bermuda is a British overseas territory in the North Atlantic Ocean. Located off the east coast of the United States, its nearest landmass is Cape Hatteras, North Carolina, about to the west-northwest. It is about south of Halifax, Nova Scotia, Canada, and northeast of Miami, Florida...
.
Tropical Storm Cindy
On July 17, an area of showers and thunderstorms, associated with the same frontal system that spawned Tropical Storm Bret, consolidated around a developing area of low pressure about 345 mi (555 km) west-southwest of Bermuda. Tracking east-northeastward, the system gradually organized and became better defined. Passing south of the territory on July 19, the disturbance produced moderate rains, peaking at 1.16 in (29.5 mm), and gusty winds across the area. On July 20, the low developed into a tropical depression east of Bermuda. Embedded within the mid-latitude westerliesWesterlies
The Westerlies, anti-trades, or Prevailing Westerlies, are the prevailing winds in the middle latitudes between 30 and 60 degrees latitude, blowing from the high pressure area in the horse latitudes towards the poles. These prevailing winds blow from the west to the east, and steer extratropical...
, the depression moved northeast and maintained this general direction for the remainder of its existence. Hours later, the system strengthened into Tropical Storm Cindy. Convection steadily increased over the storm and a ragged eye-like
Eye (cyclone)
The eye is a region of mostly calm weather found at the center of strong tropical cyclones. The eye of a storm is a roughly circular area and typically 30–65 km in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the second most severe weather of a cyclone...
featured appeared on both visible and microwave satellite imagery. Corresponding with this, Cindy attained its peak intensity just below hurricane status late on July 21 with winds of 70 mph (110 km/h) and a barometric pressure of 994 mbar (hPa; 29.35 inHg). Shortly thereafter, the storm moved over waters cooler than 78.8 °F (26 °C). Throughout July 22, convection diminished and Cindy transitioned into a post-tropical cyclone about 985 mi (1,585 km) southwest of Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...
. The remnants persisted for another 12 hours before degenerating into a trough over the North Atlantic.
Tropical Storm Don
Toward the end of July, a persistent westward moving tropical wave showed signs of organization in the Yucatan Channel. A Hurricane HuntersHurricane Hunters
The Hurricane Hunters are aircraft that fly into tropical cyclones in the North Atlantic Ocean and Northeastern Pacific Ocean for the specific purpose of directly measuring weather data in and around those storms. In the United States, the Air Force, Navy, and NOAA units have all participated in...
flight observed gale force winds and a broad circulation, which prompted the National Hurricane Center to initiate advisories on Tropical Storm Don on July 27. After the storm was named, officials in Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
began making preparations for Don. The University of Texas Medical Branch
University of Texas Medical Branch
The University of Texas Medical Branch is a component of the University of Texas System located in Galveston, Texas, United States, about 50 miles southeast of Downtown Houston...
in Galveston
Galveston, Texas
Galveston is a coastal city located on Galveston Island in the U.S. state of Texas. , the city had a total population of 47,743 within an area of...
issued a level one alert for Don, and city officials began preparing for a possible evacuation. The NHC later downgraded Don into a tropical depression then a remnant low after it quickly disintegrated upon making landfall and hitting the dry air over Texas as a result of the state's extreme drought, dropping much less than the forecasted rainfall at no more than 2/3 of an inch along the coast.
Tropical Storm Emily
A strong tropical wave tracked the open Atlantic for several days in late July. The wave remained fairly disorganized, lacking a defined circulation. By July 31, it approached the Lesser Antilles and became better defined, producing inclement weather over much of the area. Late on August 1, it finally developed a closed circulation center, prompting the National Hurricane Center to declare the formation of Tropical Storm Emily just after it had crossed the islands. On August 2, Emily continued to show signs of strengthening, even though most of the convection was off to the south and west of the circulation center. On August 4, Emily weakened into a remnant low but was expected to regenerate at least into a tropical depression. Over the next 2 days, Emily moved over the Bahamas, and up to FloridaFlorida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
's southeastern coast, as it slowly strengthened. Later, on August 6, Emily regenerated into a weak depression, dissipating again the next day. The remnants of Emily tracked east-northeastward toward Bermuda. Soon afterwards, Emily's remnants took an eastward turn, and moved towards the open Atlantic. On August 10, convection significantly re-developed in the middle of the Atlantic Ocean, and the National Hurricane Center assessed the system as having a 10% chance of regeneration into a tropical cyclone.
Tropical Storm Franklin
During the early afternoon of August 10, a disorganized area of showers and thunderstorms developed off the east coast of Florida, in association with an elongated area of low pressure. Tracking northeastward in response to deep southeasterly flow, the disturbance slowly organized; however, by the morning of August 12, the chances of the system developing into a tropical cyclone remained low. Over the following several hours, marked organization of thunderstorm activity took place around a well-defined low pressure area. Subsequently, the system was classified as Tropical Depression Six that day roughly 260 mi (420 km) north of BermudaBermuda
Bermuda is a British overseas territory in the North Atlantic Ocean. Located off the east coast of the United States, its nearest landmass is Cape Hatteras, North Carolina, about to the west-northwest. It is about south of Halifax, Nova Scotia, Canada, and northeast of Miami, Florida...
. Although well to the north of Bermuda, the system brought unsettled weather to the archipelago, with rainfall reaching 0.07 in (1.8 mm) at L.F. Wade International Airport.
Maintaining a northeasterly track, the depression intensified into Tropical Storm Franklin early on August 13 following a large burst of convection over its center. Later that morning, Franklin attained its peak winds of 45 mph (75 km/h) before encountering increasing wind shear
Wind shear
Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere...
and decreasing sea surface temperatures. Rapid deterioration of the storm's structure took place as environmental conditions became increasingly hostile for tropical cyclones. Convection was sheared more than 100 mi (155 km) from the center of circulation and Franklin began acquiring characteristics of an extratropical cyclone
Extratropical cyclone
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
. Early on August 14, Franklin quickly completed its transition into an extratropical system, prompting the final advisory from the NHC.
Tropical Storm Gert
During the second week of August, a weak low-pressure area, located east of BermudaBermuda
Bermuda is a British overseas territory in the North Atlantic Ocean. Located off the east coast of the United States, its nearest landmass is Cape Hatteras, North Carolina, about to the west-northwest. It is about south of Halifax, Nova Scotia, Canada, and northeast of Miami, Florida...
, became associated with a synoptic-scale
Synoptic scale meteorology
The synoptic scale in meteorology is a horizontal length scale of the order of 1000 kilometres or more. This corresponds to a horizontal scale typical of mid-latitude depressions...
trough. Dropping west-southwestward, it interacted with an upper low to produce an area of disorganized convection, and by then the NHC began to monitor the system. By August 13, the small low had become very well-defined, with a tight wind circulation center and deep convection; it was designated as a tropical depression at 0300 UTC that day, about 360 mi (580 km) south-southeast of Bermuda. As the depression re-curved west-northwestward along the weakening subtropical ridge
Subtropical ridge
The subtropical ridge is a significant belt of high pressure situated around the latitudes of 30°N in the Northern Hemisphere and 30°S in the Southern Hemisphere. It is characterized by mostly calm winds, which acts to reduce air quality under its axis by causing fog overnight, and haze during...
, it intensified into Tropical Storm Gert, due to light wind shear and moist air, about 15 hours after its formation. As Gert neared Bermuda, a small 7 to 9 mi (11.3 to 14.5 km) eye-like feature
Eye (cyclone)
The eye is a region of mostly calm weather found at the center of strong tropical cyclones. The eye of a storm is a roughly circular area and typically 30–65 km in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the second most severe weather of a cyclone...
became apparent on radar imagery
Weather radar
Weather radar, also called weather surveillance radar and Doppler weather radar, is a type of radar used to locate precipitation, calculate its motion, estimate its type . Modern weather radars are mostly pulse-Doppler radars, capable of detecting the motion of rain droplets in addition to the...
. Coinciding with this, Gert reached its peak intensity with winds of 65 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 degenerated into a post-tropical cyclone over the open Atlantic.
Tropical Storm Harvey
In mid-August, a westward moving tropical waveTropical wave
Tropical waves, easterly waves, or tropical easterly waves, also known as African easterly waves in the Atlantic region, are a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, which move from east to west across the tropics causing areas of...
entered the Caribbean Sea. It eventually gained enough organization to be classified as Tropical Depression Eight on August 18. It was upgraded to Tropical Storm Harvey on August 19. By late August 19 the storm was intensifying rapidly and it was announced that it could become a hurricane just before landfall. However, by Saturday afternoon, August 20, Harvey made landfall, never having reached hurricane strength, resetting the Atlantic record as the first eight named storms of the season did not reach hurricane strength. Harvey was then downgraded into a depression and it dissipated on August 22.
Hurricane Irene
In the evening of August 20, a large low pressure area became organized enough to be classified as Tropical Storm Irene. It passed over the Leeward Islands early on August 21. Early on August 22, Irene strengthened into a Category 1 hurricane, with winds of 75 mph (120 km/h) and a central pressure of 987 mbar (29.1 inHg), becoming the first hurricane of the season. This broke a streak of eight consecutive tropical cyclones to start the 2011 season, all of which did not strengthen beyond tropical storm force. Early on August 24, Irene became a Category 3 major hurricane, with winds of 120 mph (150 km/h). Irene went through a partial eyewall replacement cycleEyewall replacement cycle
Eyewall replacement cycles, also called concentric eyewall cycles, naturally occur in intense tropical cyclones, generally with winds greater than 185 km/h , or major hurricanes...
which weakened it slightly, but caused its wind field to greatly expand. On August 26, New York
New York City
New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...
mayor Michael Bloomberg
Michael Bloomberg
Michael Rubens Bloomberg is the current Mayor of New York City. With a net worth of $19.5 billion in 2011, he is also the 12th-richest person in the United States...
told coastal residents to 'get moving, now.' The next day, Irene made landfall on Cape Lookout, North Carolina as a category 1 hurricane with 85 mph winds and unusually low pressure for a category 1 hurricane. Hurricane Irene made a second U.S. landfall at Little Egg Inlet in New Jersey at 5:35 a.m., making it the first landfalling hurricane in 108 years for New Jersey. On August 28, Irene was downgraded to a tropical storm as it made its third U.S. landfall in the Coney Island
Coney Island
Coney Island is a peninsula and beach on the Atlantic Ocean in southern Brooklyn, New York, United States. The site was formerly an outer barrier island, but became partially connected to the mainland by landfill....
area of Brooklyn, New York, at approximately 9:00 a.m. on August 28. Irene became a post-tropical storm over Quebec
Quebec
Quebec or is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking population and the only one whose sole official language is French at the provincial level....
and Atlantic Canada
Atlantic Canada
Atlantic Canada is the region of Canada comprising the four provinces located on the Atlantic coast, excluding Quebec: the three Maritime provinces – New Brunswick, Prince Edward Island, and Nova Scotia – and Newfoundland and Labrador...
on August 29.
Forming on August 20, Irene was the second earliest ninth Atlantic tropical cyclone on record, along with an unnamed tropical storm from the 1936 season
1936 Atlantic hurricane season
The 1936 Atlantic hurricane season officially began on June 16, 1936, and lasted until October 31, 1936. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin....
. At least 55 people were confirmed dead across the Caribbean, 10 U.S. states and Canada in the aftermath and damage from Hurricane Irene totaled $10.1 billion (2011 USD).
Tropical Depression Ten
In late August, a new, well-defined tropical wave moved off the west coast of Africa into the Atlantic Ocean. By August 25, the system had developed sufficient deep convection for the NHC to classify it as Tropical Depression Ten. At this time, the depression attained its peak intensity with winds of 35 mph (55 km/h) and a minimum pressure of 1007 mbar (hPa). Shortly thereafter, wind shear and decreasing sea surface temperatures caused the depression to weaken, degenerating into a remnant low by the evening hours of August 26.Tropical Storm Jose
On August 17, a tropical waveTropical wave
Tropical waves, easterly waves, or tropical easterly waves, also known as African easterly waves in the Atlantic region, are a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, which move from east to west across the tropics causing areas of...
exited the west coast of Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
. During the first few days, the tropical wave produced convection, as it slowly moved westward, and became associated with an area of low pressure. But by the next week, the wave dissipated to a weak area of low pressure – due to high wind shear – as it began to move northwestward, while fluctuating slightly in intensity. In the next few days, the tropical wave approached Bermuda
Bermuda
Bermuda is a British overseas territory in the North Atlantic Ocean. Located off the east coast of the United States, its nearest landmass is Cape Hatteras, North Carolina, about to the west-northwest. It is about south of Halifax, Nova Scotia, Canada, and northeast of Miami, Florida...
; while remaining disorganized, and weakening even further. 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
Bermuda
Bermuda is a British overseas territory in the North Atlantic Ocean. Located off the east coast of the United States, its nearest landmass is Cape Hatteras, North Carolina, about to the west-northwest. It is about south of Halifax, Nova Scotia, Canada, and northeast of Miami, Florida...
; 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. 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 IrelandNorthern Ireland
Northern Ireland is one of the four countries of the United Kingdom. Situated in the north-east of the island of Ireland, it shares a border with the Republic of Ireland to the south and west...
and Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
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
Saint Petersburg
Saint Petersburg is a city and a federal subject of Russia located on the Neva River at the head of the Gulf of Finland on the Baltic Sea...
.
Tropical Storm Lee
In late August, a tropical wave producing scattered showers and thunderstorms entered the Western Caribbean. Moving generally west-northwestward, the wave began to organize in the southeastern portion of the Gulf of Mexico. During the afternoon hours of September 1, the hurricane hunters went out to investigate the well-defined wave, and found a closed low-level circulation. Thus, advisories were initiated on Tropical Depression Thirteen. Moving northwest, the tropical depression was upgraded to a tropical storm, given the name "Lee" on September 2. Continuing to organize, Lee reached a peak intensity of 60 mph (95 km/h) early on September 3, while located just south of LouisianaLouisiana
Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...
. At 4 a.m. CDT September 4, Lee made landfall roughly 50 miles (80.5 km) to the southwest of Lafayette, Louisiana
Lafayette, Louisiana
Lafayette is a city in and the parish seat of Lafayette Parish, Louisiana, United States, on the Vermilion River. The population was 120,623 at the 2010 census...
with maximum sustained winds of 45 mph (75 km/h). Further weakening occurred as Lee moved across Louisiana, and the last NHC advisory on Lee was issued early on September 5, while its remnants proceeded to wreak havoc (mainly flooding) over the following two to three days northward into Pennsylvania, New York State and Canada (Quebec
Quebec
Quebec or is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking population and the only one whose sole official language is French at the provincial level....
and Ontario
Ontario
Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....
).
Hurricane Maria
On September 5, a low pressure area associated with a tropical wave to the west of Africa quickly organized. It was designated Tropical Depression Fourteen on the evening of September 6. On the morning of September 7, it was upgraded to Tropical Storm Maria. Over the tropical Atlantic, high wind shear hindered its development, and Maria nearly dissipated, before convection began to rebuild by September 9. The following day, it began to encounter more favorable conditions, and the tropical cyclone intensified into a Category 1 hurricane on September 15. On the afternoon of September 16, the storm lost tropical characteristics off the northeast coast of Newfoundland. Landfall was reported on the southern tip of the Avalon PeninsulaAvalon Peninsula
The Avalon Peninsula is a large peninsula that makes up the southeast portion of the island of Newfoundland.The peninsula is home to 257,223 people, which is approximately 51% of Newfoundland's population in 2009, and is the location of the provincial capital, St. John's. It is connected to the...
with winds recorded at 64 mph (103 km/h). The capital city of St. John's
St. John's, Newfoundland and Labrador
St. John's is the capital and largest city in Newfoundland and Labrador, and is the oldest English-founded city in North America. It is located on the eastern tip of the Avalon Peninsula on the island of Newfoundland. With a population of 192,326 as of July 1, 2010, the St...
experienced heavy rain and gale-force winds, but not as severe as anticipated.
Hurricane Nate
During the morning hours of September 6, shower and thunderstorm activity associated with a low pressure system began to gather organization in the Bay of Campeche. The following day, the system gained enough organization to be classified as a tropical storm, earning the name Nate. Moving in an erratic motion at a very slow pace, Nate began to strengthen. During the afternoon hours of September 8, Nate reached its peak intensity of 75 mph (120 km/h), while moving off towards the Mexican coastline. The storm was originally thought to remain a tropical storm, but post-season analysis revealed that Nate was a hurricane for twelve hours based on data from PEMEXPemex
Petróleos Mexicanos or Pemex is a Mexican state-owned petroleum company. As of 2010, with a total asset worth of $415.75 billion, it is the second non-publicly listed largest company in the world by total market value, and Latin America's second largest enterprise by annual revenue as of 2009...
oil rigs not available operationally. Due to the storm's slow movement, Nate began to upwell cooler waters in its wake, resulting in weakening. Additionally, very dry air began getting entrained into the system. On September 11, Nate made landfall on the Mexican coastline as a weak tropical storm, with maximum sustained winds of 45 mph (75 km/h). Shortly after making landfall, much of Nate's showers and thunderstorms dissipated, and thus rainfall totals were not as high as expected.
Hurricane Ophelia
In mid-September, a well-defined tropical wave emerged off the African coastline. Moving westward, the disturbance began to gather organization, and become very well defined on September 20. Subsequently, the National Hurricane Center started issuing advisories on Tropical Storm Ophelia. Almost as soon as it became a tropical storm, vertical wind shearWind shear
Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere...
began impacting the system. Ophelia slowly strengthened despite the unfavorable conditions and attained winds of 65 mph (100 km/h) on September 22. The system briefly weakened to a minimal tropical storm before strengthening again. However, because of the extremely strong wind shear, Ophelia was ripped apart and dissipated into a post-tropical remnant low on September 25.
Wind shear remained strong, but not as strong as before. Thus, during the afternoon hours of September 27, Ophelia was able to develop convection near its center, and was designated a tropical depression. Ophelia gradually strengthened further into a tropical storm as it passed to the north of the Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
. In Dominica
Dominica
Dominica , officially the Commonwealth of Dominica, is an island nation in the Lesser Antilles region of the Caribbean Sea, south-southeast of Guadeloupe and northwest of Martinique. Its size is and the highest point in the country is Morne Diablotins, which has an elevation of . The Commonwealth...
, heavy rains from the storm caused widespread flooding. During the afternoon hours of September 29, despite the relatively unfavorable environment, Ophelia strengthened into a Category 1 hurricane. As wind shear relaxed, early on September 30, Ophelia rapidly intensified
Rapid deepening
Rapid deepening, also known as rapid intensification, is a meteorological condition that occurs when the minimum sea-level atmospheric pressure of a tropical cyclone decreases drastically in a short period of time. The National Weather Service describes rapid deepening as a decrease of...
and became a Category 2 hurricane. Later that day, Ophelia further strengthened into a Category 3 hurricane, becoming the third major hurricane of the season. The eye of Ophelia passed directly over a NOAA buoy
Buoy
A buoy is a floating device that can have many different purposes. It can be anchored or allowed to drift. The word, of Old French or Middle Dutch origin, is now most commonly in UK English, although some orthoepists have traditionally prescribed the pronunciation...
early on October 1, which reported sustained winds of 96 mph (155 km/h) and a pressure of 952 mbar (28.11 inHg). The intensification trend continued, and Ophelia strengthened further to a Category 4 hurricane late that day east of Bermuda
Bermuda
Bermuda is a British overseas territory in the North Atlantic Ocean. Located off the east coast of the United States, its nearest landmass is Cape Hatteras, North Carolina, about to the west-northwest. It is about south of Halifax, Nova Scotia, Canada, and northeast of Miami, Florida...
. Through the following day (Sunday), increasing southwesterly wind shear and cooler water temperatures combined to cause Ophelia to progressively weaken back into a Category 1 hurricane by evening and weakened to a tropical storm during the morning hours of October 3. Several hours later, Ophelia was declared as a post-tropical cyclone soon after making landfall on the Avalon Peninsula
Avalon Peninsula
The Avalon Peninsula is a large peninsula that makes up the southeast portion of the island of Newfoundland.The peninsula is home to 257,223 people, which is approximately 51% of Newfoundland's population in 2009, and is the location of the provincial capital, St. John's. It is connected to the...
in Newfoundland.
Hurricane Philippe
On September 23, a well-defined tropical waveTropical wave
Tropical waves, easterly waves, or tropical easterly waves, also known as African easterly waves in the Atlantic region, are a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, which move from east to west across the tropics causing areas of...
emerged off the coast of Africa, associated with plentiful shower and thunderstorm activity
Atmospheric convection
Atmospheric convection is the result of a parcel-environment instability, or temperature difference, layer in the atmosphere. Different lapse rates within dry and moist air lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to...
. Moving westward and embedded within a favorable environment for development, the wave quickly became organized. During the morning hours of September 24, the National Hurricane Center designated the low as a tropical depression, while located about 290 mi (465 km) south of the southernmost Cape Verde Islands. Later that day, the depression was upgraded to a tropical storm, designated "Philippe". Since that time strong shear from both upper level winds and later on from Ophelia's outflow, as well as periodic entrainment of dry air kept the cyclone both small and disorganized, with the center often exposed to the point where the low level circulation reformed under the convection that defines a tropical system at least once. An exposed cyclone can be seen as a wispy series of clouds circling a small area, rather than under the canopy of thunderstorms. Because of this hostile environment, Philippe remained near the minimum for a tropical storm. On the afternoon of October 2, an Advanced Scatterometer (ASCAT)
Scatterometer
A radar scatterometer is designed to determine the normalized radar cross section of the surface. Scatterometers operate by transmitting a pulse of microwave energy towards the Earth's surface and measuring the reflected energy. A separate measurement of the noise-only power is made and...
pass confirmed that Philippe was a strong tropical storm, contrary to satellite estimates. Despite high wind shear, it remained a strong tropical storm afterward and actually at times developed an eye
Eye (cyclone)
The eye is a region of mostly calm weather found at the center of strong tropical cyclones. The eye of a storm is a roughly circular area and typically 30–65 km in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the second most severe weather of a cyclone...
feature. On October 6, after over 12 days as a tropical storm, Philippe became a strong Category 1 hurricane. On October 8, Philippe weakened to a tropical storm, then became post-tropical hours later, on October 9.
Hurricane Rina
In mid-October, the southern extension of a cold frontCold front
A cold front is defined as the leading edge of a cooler mass of air, replacing a warmer mass of air.-Development of cold front:The cooler and denser air wedges under the less-dense warmer air, lifting it...
moved into the western Caribbean. The front, in conjunction with east-southeasterly trade winds, produced a broad area of cyclonic circulation over the southwestern Caribbean. Moving slowly towards the north and northwest, barometric pressures in the area began falling, and the disturbance was expected to move into an environment more conducive for development. Thus, the National Hurricane Center gave the disturbance a medium chance, 30%, of developing into a tropical cyclone within 48 hours. Further organization occurred during the afternoon hours of October 21, as the low pressure area became more consolidated. However, the following day, the disturbance became slightly less organized, depicted by a decrease in tropical cyclone formation probabilities.
On October 23, a reconnaissance aircraft
Hurricane Hunters
The Hurricane Hunters are aircraft that fly into tropical cyclones in the North Atlantic Ocean and Northeastern Pacific Ocean for the specific purpose of directly measuring weather data in and around those storms. In the United States, the Air Force, Navy, and NOAA units have all participated in...
flew into the disturbance, finding a well-defined center of circulation. This, combined with satellite imagery
Satellite imagery
Satellite imagery consists of photographs of Earth or other planets made by means of artificial satellites.- History :The first images from space were taken on sub-orbital flights. The U.S-launched V-2 flight on October 24, 1946 took one image every 1.5 seconds...
, led to the formation of Tropical Depression Eighteen during the evening hours of that day; it strengthened to a tropical storm just several hours later, and earned the name "Rina". Moving towards the north-northwest, Rina rapidly intensified
Rapid deepening
Rapid deepening, also known as rapid intensification, is a meteorological condition that occurs when the minimum sea-level atmospheric pressure of a tropical cyclone decreases drastically in a short period of time. The National Weather Service describes rapid deepening as a decrease of...
on October 24, becoming a hurricane just 21 hours after formation. Further strengthening commenced for the remaining of the day, although Rina did not reach peak intensity until the evening hours of October 25. Shortly thereafter, the increase of wind shear and dry air led to weakening the following day, and Rina weakened to a tropical storm early on October 27. Scraping the Yucatan Peninsula, Rina brought heavy rainfall and gusty winds before turning towards the north. Early the next day, Rina weakened into a tropical depression, and during the afternoon hours, further dissipated into a remnant low.
Tropical Storm Sean
During the mid-afternoon of November 4, the non-tropical cyclone that would later become Tropical Storm Sean, emerged off the extreme southern coast of North CarolinaNorth Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...
. On November 6, the National Hurricane Center began monitoring a non-tropical area of low pressure producing a large area of gale force winds to the southwest of Bermuda. Moving towards the south and southeast, the low pressure area began to enter higher Sea Surface Temperatures and subsequently became better organized. By the early morning hours of November 8, the low had become sufficiently organized to be declared as a subtropical storm, and then a fully tropical storm several hours later. Sean strengthened to attain a peak intensity of 65 mph (100 km/h) on November 9 and 10 before it began to enter an area of higher wind shear. Early on November 12, Sean was absorbed by a cold front, associated with a powerful extratropical cyclone centered over Newfoundland
Newfoundland
Newfoundland usually refers to either:* Newfoundland, the former name of Newfoundland and Labrador, a Canadian province in the eastern part of Canada* Newfoundland , an island that forms part of the province of Newfoundland and Labrador...
, while Sean was located several hundred miles to the northeast of Bermuda.
Storm names
The following names were used for named storms in the North Atlantic in 2011. Names that were not used are marked in gray. This is the same list used in the 2005 season2005 Atlantic hurricane season
The 2005 Atlantic hurricane season was the most active Atlantic hurricane season in recorded history, repeatedly shattering numerous records. The impact of the season was widespread and ruinous with an estimated 3,913 deaths and record damage of about $159.2 billion...
with the exception of Don, Katia, Rina, Sean, and Whitney, which replaced Dennis
Hurricane Dennis
Hurricane Dennis was an early-forming major hurricane in the Caribbean and Gulf of Mexico during the very active 2005 Atlantic hurricane season. Dennis was the fourth named storm, second hurricane, and first major hurricane of the season...
, Katrina
Hurricane Katrina
Hurricane Katrina of the 2005 Atlantic hurricane season was a powerful Atlantic hurricane. It is the costliest natural disaster, as well as one of the five deadliest hurricanes, in the history of the United States. Among recorded Atlantic hurricanes, it was the sixth strongest overall...
, Rita
Hurricane Rita
Hurricane Rita was the fourth-most intense Atlantic hurricane ever recorded and the most intense tropical cyclone ever observed in the Gulf of Mexico. Rita caused $11.3 billion in damage on the U.S. Gulf Coast in September 2005...
, Stan
Hurricane Stan
Hurricane Stan was the eighteenth named tropical storm and eleventh hurricane of the 2005 Atlantic hurricane season. It was also the sixth of seven tropical cyclones to make landfall in Mexico. Stan was a relatively weak storm that only briefly reached hurricane status...
, and Wilma
Hurricane Wilma
Hurricane Wilma was the most intense tropical cyclone ever recorded in the Atlantic basin. Wilma was the twenty-second storm , thirteenth hurricane, sixth major hurricane, and fourth Category 5 hurricane of the record-breaking 2005 season...
, respectively. The names Don, Katia, Rina, and Sean were used for the first time in the Atlantic Basin. Retired names, if any, will be announced by the World Meteorological Organization
World Meteorological Organization
The World Meteorological Organization is an intergovernmental organization with a membership of 189 Member States and Territories. It originated from the International Meteorological Organization , which was founded in 1873...
in the spring of 2012. The names not retired from this list will be used again in the 2017 season.
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Tropical Storm Harvey (2011) Tropical Storm Harvey was a tropical storm that formed and dissipated during the 2011 Atlantic hurricane season. Harvey was also the last in a record-breaking string of eight consecutive storms that reached only tropical storm status. Hurricane Irene, the next storm to form after Harvey, reached... Hurricane Irene (2011) Hurricane Irene was a large and powerful Atlantic hurricane that left extensive flood and wind damage along its path through the Caribbean, the United States East Coast and as far north as Atlantic Canada in 2011... Hurricane Katia (2011) Hurricane Katia was the eleventh named storm, second hurricane and second major hurricane of the 2011 Atlantic hurricane season. A Cape Verde-type hurricane, Katia developed from a tropical wave south of the Cape Verde Islands on August 29. Tracking west-northwestward, the system gradually... Tropical Storm Lee (2011) Tropical Storm Lee was the twelfth named storm and thirteenth system overall of the 2011 Atlantic hurricane season, developing from a broad tropical disturbance over the Gulf on September 1. It was designated as Tropical Storm Lee the next day... Hurricane Maria (2011) Hurricane Maria was the thirteenth named storm and third hurricane of the 2011 Atlantic hurricane season. Maria developed from a strong tropical wave that moved off the coast of Africa in early September. Moving westward, the wave organized rapidly, and became a tropical storm on September 6... Hurricane Nate (2011) Hurricane Nate was an Atlantic hurricane that made landfall on the Gulf Coast of Mexico in early September. The sixteenth named storm and fourth hurricane of the 2011 Atlantic hurricane season, Hurricane Nate formed in the Bay of Campeche on September 7 and initially moved erratically... |
Hurricane Ophelia (2011) Hurricane Ophelia was a relatively large Atlantic tropical cyclone that affected the Leeward Islands, Bermuda, and Newfoundland during September and October 2011... Hurricane Rina Hurricane Rina was the eighteenth tropical cyclone, seventeenth named storm, and sixth hurricane of the 2011 Atlantic hurricane season. Rina developed from a low-pressure area in the western Caribbean Sea on October 23. The depression quickly intensified, and was upgraded to Tropical Storm Rina... Tropical Storm Sean (2011) Tropical Storm Sean was a tropical cyclone that affected the island of Bermuda in November of the 2011 Atlantic hurricane season. The nineteenth tropical system and the eighteenth named storm of the 2011 season, Sean developed from a non-tropical low pressure area on November 8. Initially... |
Season effects
This is a table of all of the storms that have formed in the 2011 Atlantic hurricane season. It includes their duration, names, landfall(s) –denoted by bold location names – damages, 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 2011 USD.Accumulated Cyclone Energy (ACE)
The table on the right shows the ACEAccumulated cyclone energy
Accumulated cyclone energy is a measure used by the National Oceanic and Atmospheric Administration to express the activity of individual tropical cyclones and entire tropical cyclone seasons, particularly the North Atlantic hurricane season. It uses an approximation of the energy used by a...
for each storm in the season. Broadly speaking, the ACE is a measure of the power of a 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 calculated for only full advisories on specifically tropical systems reaching or exceeding wind speeds of 34 knots (39 mph, 63 km/h), or tropical storm strength. Accordingly, tropical depressions are not included here. The ACE also does not include subtropical storms, therefore values accrued while Sean was subtropical are not calculated in its ACE. Later the NHC reexamines the data, and produces a final report on each storm, which can lead to the ACE for a storm being revised either upward or downward. Until the final reports are issued, ACEs are, therefore, provisional.
See also
- List of Atlantic hurricanes
- List of Atlantic hurricane seasons
- 2011 Pacific hurricane season2011 Pacific hurricane seasonThe 2011 Pacific hurricane season is an ongoing, annual cycle of tropical cyclone formation. The season officially started on May 15, 2011, for the eastern Pacific, and started on June 1, 2011, for the central Pacific, both of which ended on November 30, 2011. These dates conventionally...
- 2011 Pacific typhoon season2011 Pacific typhoon seasonThe 2011 Pacific typhoon season was the time of the year in which tropical cyclones form in the Western Pacific Ocean. The season ran throughout 2011 with most tropical cyclones forming between May and November. The scope of this article is limited to the Pacific Ocean to the north of the equator...
- 2011 North Indian Ocean cyclone season2011 North Indian Ocean cyclone seasonThe 2011 North Indian Ocean cyclone season is an event in the annual cycle of tropical cyclone formation. The North Indian Ocean cyclone season has no official bounds, but cyclones tend to form between April and December, with peaks in May and November...
- Timeline of the 2011 Atlantic hurricane seasonTimeline of the 2011 Atlantic hurricane seasonThe 2011 Atlantic hurricane season was an above-average Atlantic hurricane season, with a total of nineteen named storms throughout the Gulf of Mexico, Caribbean, and Atlantic basin...
- South-West Indian Ocean cyclone seasons: 2010–112010–11 South-West Indian Ocean cyclone seasonThe 2010–11 South-West Indian Ocean cyclone season was the least active tropical cyclone season in the South-West Indian Ocean on record. It began on November 1, 2010 and ended on April 30, 2011, dates which conventionally delimit the year in which most tropical cyclones form in the basin...
, 2011–122011–12 South-West Indian Ocean cyclone seasonThe 2011–12 South-West Indian Ocean cyclone season is an event in the annual cycle of tropical cyclone formation. It began on November 15, 2011, and will end on April 30, 2012, with the exception for Mauritius and the Seychelles, for which it will end on May 15, 2012... - Australian region cyclone seasons: 2010–112010–11 Australian region cyclone seasonThe 2010–11 Australian region cyclone season was a near average tropical cyclone season, with eleven tropical cyclones forming compared to an average of 12. The season began on 1 November 2010 and ended on 30 April 2011. The Australian region is defined as being to south of the equator, between the...
, 2011–122011–12 Australian region cyclone seasonThe 2011–12 Australian region cyclone season is an event in the ongoing cycle of tropical cyclone formation. It began on 1 November 2011, and it will end on 30 April 2012... - South Pacific cyclone seasons: 2010–112010–11 South Pacific cyclone seasonThe 2010–11 South Pacific cyclone season is a period of the year when tropical cyclones formed within the South Pacific Ocean to the east of 160°E...
, 2011–122011–12 South Pacific cyclone seasonThe 2011–12 South Pacific cyclone season will be the period of the year when most tropical cyclones form within the South Pacific Ocean to the east of 160°E. The season officially runs from November 1, 2011 to April 30, 2012...