The 2011 Atlantic hurricane season is an event in the annual cycle of tropical cyclone formation. The season officially started on June 1 and will end on November 30. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin. However, should a tropical or subtropical cyclone form outside these dates during the calendar year 2011, it would count as part of the 2011 season.
Pre-season forecasts
On December 8, 2010, Klotzbach's 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. As well, the team expected an accumulated cyclone energy (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 temperatures, a weakening La Niña, and the effect of the warm regime of the Atlantic multidecadal oscillation as the bases behind their forecast, adding that seasonal climate models hint that "activity comparable to some of the active seasons since 1995" could occur. On June 1, CSU issued its start-of-season forecast, with numbers unchanged from the numbers published in April. Storm names
The following names will be used for named storms that form in the North Atlantic in 2011. 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. This is the same list used in the 2005 season with the exception of Don, Katia, Rina, Sean, and Whitney, which replaced Dennis, Katrina, Rita, Stan, and Wilma, respectively.
Arlene (unused) Harvey (unused) Ophelia (unused)Seasonal forecasts
Noted hurricane experts Philip J. Klotzbach, William M. Gray, and their associates at Colorado State University issue forecasts of hurricane activity each year, separately from the National Oceanic and Atmospheric Administration (NOAA). Klotzbach's team, formerly led by Gray, determined the average number of storms per season between 1950 and 2000 to be 9.6 tropical storms, 5.9 hurricanes, and 2.3 major hurricanes (storms of at least Category 3 on the Saffir-Simpson Hurricane Scale). A normal season, as defined by NOAA, has 9 to 12 named storms, of which 5 to 7 reach hurricane strength and 1 to 3 become major hurricanes.Pre-season forecasts
On December 8, 2010, Klotzbach's 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. As well, the team expected an accumulated cyclone energy (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 temperatures, a weakening La Niña, and the effect of the warm regime of the Atlantic multidecadal oscillation as the bases behind their forecast, adding that seasonal climate models hint that "activity comparable to some of the active seasons since 1995" could occur. On June 1, CSU issued its start-of-season forecast, with numbers unchanged from the numbers published in April. Storm names
The following names will be used for named storms that form in the North Atlantic in 2011. 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. This is the same list used in the 2005 season with the exception of Don, Katia, Rina, Sean, and Whitney, which replaced Dennis, Katrina, Rita, Stan, and Wilma, respectively.
Bret (unused) Irene (unused) Philippe (unused)
Cindy (unused) Jose (unused) Rina (unused)
Don (unused) Katia (unused) Sean (unused)
Emily (unused) Lee (unused) Tammy (unused)
Franklin (unused) Maria (unused) Vince (unused)
Gert (unused) Nate (unused) Whitney (unused)
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