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2007 Atlantic hurricane season

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Through El Niño–Southern Oscillation

Pre-season forecasts by Colorado State University called for 14 named storms and 7 hurricanes, of which three were expected to attain major hurricane status. The National Oceanic and Atmospheric Administration (NOAA) later issued its initial forecast, which predicted 13 to 17 named storms, 7 to 10 hurricanes and three to five major hurricanes. After several revisions in the projected number of storms, NOAA and CSU lowered their forecasts by the middle of the season.

Several storms made landfall or directly affected land. Hurricanes Dean and Felix made landfall at Category 5 intensity, causing severe damage in parts of Mexico and Central America, respectively. Both storm names, as well as Noel, the name of a hurricane that affected the Caribbean, were retired from the naming list of Atlantic hurricanes. The United States was affected by five cyclones, although the storms were generally weak; three tropical depressions and only two tropical storms, Barry and Gabrielle, and one hurricane, Humberto, made landfall in the country. Elsewhere, three storms directly affected Canada, although none severely. The combined storms killed at least 416 people and caused about $3.24 billion (2007 USD, 5.04 billion 2026 USD) in damage.

Seasonal forecasts

Philip J. Klotzbach, William M. Gray, and their associates at Colorado State University issue forecasts of hurricane activity each year, separately from 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 exceeding Category 3 on the Saffir–Simpson scale). A normal season, as defined by NOAA, has 9 to 12 named storms, of which five to seven reach hurricane strength, and one to three become major hurricanes.

Pre-season forecasts

On December 8, 2006, Klotzbach's team issued its first extended-range forecast for the 2007 season, predicting above-average activity (14 named storms, seven hurricanes, three of Category 3 or higher). It listed a 64 percent chance of at least one major hurricane striking the U.S. mainland. This included a 40 percent chance of at least one major hurricane strike on the East Coast, including the Florida peninsula, and a 40 percent chance of at least one such strike on the Gulf Coast from the Florida Panhandle westward. The potential for major hurricane activity in the Caribbean was forecast to be above average, and the team predicted that El Niño, associated with reduced hurricane activity in the Atlantic, would dissipate by the active portion of the season.

On April 3 a new forecast was issued, calling for a very active hurricane season of 17 named storms, nine hurricanes and five intense hurricanes. The increase in the forecast was attributed to the rapid dissipation of El Niño conditions. The team also forecast a neutral or weak-to-moderate La Niña and noted that sea surface temperatures were much higher than average. The estimated potential for at least one major hurricane to affect the U.S. was increased to 74 percent; the East Coast potential increased to 50 percent, and from the Florida Panhandle westward to Brownsville, Texas, the probability rose to 49 percent. However, the team's report noted that while they predicted an active season, it was not suggesting that 2007 would be "as active as the 2004 and 2005 seasons".

Midseason outlooks

On June 19 the UK Met Office (UKMO) issued a forecast of 10 tropical storms in the July to November period with a 70 percent chance that the number would be in the range of 7 to 13. On August 3, 2007, Klotzbach's team lowered its season estimate to 15 named storms, of which eight were to become hurricanes and four to become major hurricanes. Team members noted that conditions had become slightly less favorable for storms than earlier in the year. Sea surface temperature anomalies were cooler, and several Saharan Air Layer events had suppressed development of tropical cyclones. El Niño-Southern Oscillation (ENSO) conditions were also noted to have been slightly cooler.

On August 9, 2007, NOAA revised its season estimate slightly downwards to 13 to 16 named storms, of which seven to nine were to be hurricanes, and three to five major hurricanes. However, the agency reaffirmed its prediction of an above-average season, citing warmer-than-normal sea surface temperatures in parts of the Atlantic Ocean and Caribbean and the likelihood of La Niña conditions during the peak of the season.

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