Dodging a Bullet
Dreadfully busy. That’s probably the best way to describe the 2011 hurricane season. In all, there were 19 tropical storms and 7 hurricanes. Four hurricanes became “major” ones, that is, their winds exceeded 110 miles per hour.
The 2011 hurricane season was so busy, in fact, that we tied
the highest record of tropical storms since record-keeping began. [1] We also
had two more major hurricanes than average. But what made this season so odd
was not the number of storms, but the lack of number of storms that actually
made landfall. Irene was the only hurricane to make landfall, and Lee the only
tropical storm to hit the U.S.
Indeed, we dodged a bullet. The average number of named
storms per year is only 11.5. We had 19 named (tropical) storms. Thus, it stood
to reason that we would also have an above average number of landfalling hurricanes
– the average is 1.7 per year. [2] We had a few very close calls, nonetheless.
(Read more about them in The Big 7).
The Reasons
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| Map of Sea Surface Temperatures in May 2011. Retrieved from Examiner. In Public Domain Courtesy: NCEP/NWS |
There are many complex patterns within the climate that
resulted in this above average season. A
significant contributing factor to the busy season was La Niña. [3] La Niña is an
issue that originates as a result of weather off the west coast of South
America, but it has profound effects across the globe. One of those effects was
reduced winds in the Atlantic Ocean, which allowed hurricanes to approach the
coast without having to fight the winds.
Higher-than-average sea surface temperatures were also to
blame. [3] Because hurricanes need energy (in the form of heat), the above average temperature
of 2 degrees Fahrenheit helped feed the storms.The picture to the left shows how parts of the Atlantic were warm enough for hurricane development in May, even though the Atlantic Hurricane Season doesn't start until June 1. Hurricanes need temperatures of 82 degrees F (28 C) to develop.
1. "Active 2011 Hurricane Season Breaks 'Hurricane Amnesia'" NOAA News. National Oceanic and Atmospheric Administration, 28 Nov. 2011. Web. 27 Feb. 2012.
2. Landsea, Chris. "How Many Tropical Cyclones Have There Been Each Year in the Atlantic Basin?" Hurricane FAQ. Hurricane Research Divsion, NOAA, 26 May 2011. Web. 27 Feb. 2012.
3. NOAA. "NOAA Hurricane Outlook Indicates an Above-normal Atlantic Season." NOAA News. National Oceanic and Atmospheric Administration, 19 May 2011. Web. 27 Feb. 2012.
1. "Active 2011 Hurricane Season Breaks 'Hurricane Amnesia'" NOAA News. National Oceanic and Atmospheric Administration, 28 Nov. 2011. Web. 27 Feb. 2012.
2. Landsea, Chris. "How Many Tropical Cyclones Have There Been Each Year in the Atlantic Basin?" Hurricane FAQ. Hurricane Research Divsion, NOAA, 26 May 2011. Web. 27 Feb. 2012.
3. NOAA. "NOAA Hurricane Outlook Indicates an Above-normal Atlantic Season." NOAA News. National Oceanic and Atmospheric Administration, 19 May 2011. Web. 27 Feb. 2012.
