Not much hurricane activity for 2009

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Wednesday, December 2, 2009

The 2009 Atlantic hurricane season officially ended Monday. If you're saying, "Gee, I didn't hear much about hurricanes this year," you'd be right.

The nine named storms were only one short of the 10 seen in an average season. (A storm is named if it becomes a tropical storm, which means winds of at least 39 mph.) But only three became hurricanes (74-mph winds or stronger) compared with six in an average season. Last year there were 16 named storms and eight hurricanes.

Another measure of this year's hurricane season is the "accumulated cyclone energy," or ACE for short. ACE is based on the number of storms, how strong they are and how long they last. This year's ACE for the Atlantic was 52. The average is 106, and last year's ACE was 145, or almost three times as big as this year's.

Here's one more statistic: The total number of flights by the National Hurricane Center for the 2009 hurricane season was 38. Last year there were 169 flights. The average number of flights per year from 2004 to 2008 was 130. The hurricane center flies aircraft into storms to gather data. Forecasters and scientists use the data to improve forecasts of hurricanes and study how they work.

Most of this year's storms had little impact on land or people. An exception was Ida, the only storm to form during the final seven weeks of the season.

Ida made landfall as a tropical storm on Nov. 10 along the Gulf Coast, causing mostly minor flooding. The remnants of Ida turned into a large storm that resulted in flooding rains and fierce winds for parts of the East Coast, including Virginia.

So why was 2009 such a quiet hurricane season?

Experts think El Niño helped to limit the number of hurricanes this year. El Niño is the periodic warming of waters in the Pacific Ocean along the equator. It leads to winds over the Atlantic Ocean that change direction and speed with height. Such winds tend to rip storms apart, or prevent them from forming in the first place.

Now that the 2009 hurricane season is over, we can look forward to next year. The first named storm in 2010 will be Alex. Is your name on the 2010 list? Go to http://www.nhc.noaa.gov/aboutnames.shtml to find out, but ask your parents first.

-- Dan Stillman

The author is lead meteorologist for washingtonpost.com's Capital Weather Gang. For the latest weather news, check out http://washingtonpost.com/capitalweathergang.


© 2009 The Washington Post Company

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