An El Niño is a weather phenomenon produced by unusually warm waters off the northwest coast of South America. The event causes prevailing upper level winds – known as the jet stream – to shift southward over the Atlantic. The winds disrupt hurricane formation.
But meteorologists think next summer could be more active than this year because the El Niño effect probably is going to dissipate before next spring. And while the El Niño kept the lid on the Atlantic season, it was a major factor in a very active hurricane season in the Pacific. The central and eastern Pacific saw 20 named storms, including powerful Hurricane Rick, the second-most-powerful hurricane on record for the Pacific.
Meteorologists at Colorado State University also noted a few other characteristics of the 2009 Atlantic hurricane season, including:
• A late-starting season. Tropical Storm Ana – the season’s first named storm – did not form until August 15. That’s the latest that the first storm formed since 1992. That year’s first storm was memorable, however, because it was Hurricane Andrew.
• The nine named storms that occurred during 2009 are the fewest since 1997 when eight named storms formed.
• There were 27.25 days during which a named storm was active. That’s the lowest number since 1991, when only 24.25 named storm days were recorded.
• Three hurricanes occurred in 2009 - the fewest hurricanes since 1997 when there were also three hurricanes.
• There were only 11.25 days during which a hurricane was active, the fewest hurricane days since 2002 when 10.75 hurricane days were reported.
• Only two major hurricanes formed during the 2009 hurricane season. The last time that fewer than two major hurricanes occurred in a season was in 1997 when only one major hurricane (Erika) formed.
• No Category 5 hurricanes developed in the Atlantic in 2009. This is the second consecutive year with no Category 5 hurricanes. The last time that two or more years occurred in a row with no Category 5 hurricanes was 1999-2002.
• No named storms formed in June or July. The last time that no storm activity occurred in June or July was 2004 (Alex formed that year on August 1). This is the 18th year of the past 66 years with no storm formations in June or July.