Facts Worth Knowing About Tropical Storms

Satellite image of Hurricane Rafael, courtesy of NOAA

Here we are in the middle of October, well past the peak of the tropical storm season. Yet, the final advisory for Hurricane Rafael, the 17th named storm of the season, was just issued yesterday. The actual peak of the season happens on September 10th, and the season officially ends on November 30th, but the number of tropical cyclones rapidly declines after the September 10th peak. Here are some other interesting facts from the Atlantic Basin:

1.There are more storms beginning with the letters "I" and "C" that have been retired than any other letter. Since 1954, when the naming convention became official, 9 "I" and "C" named storms have been retired. Of course, 2011's Irene is one of these retired names. 

2.In the entire 68-year history of named tropical storms, only one name- Allison- was retired without the storm ever reaching hurricane status. Despite the lack of wind, experts decided to retire Allison because of the devastating floods that it caused, especially in the Houston metro area, in 2001.

3.We all remember the record-breaking year of 2005 for several reasons- It was the year when we literally ran out of names for tropical storms, and had to use Greek letters; it was the year with the latest hurricane formation of any season; and of course, it was the year of Katrina.

4.The 2005 season will be remembered for generations to come, because it was the year with the most storm names retired; in addition to Katrina, the names Dennis, Rita, Stan and Wilma have also been removed from the rolls. 

5.In most years, the first hurricane of the season forms in June, but one of the most notorious hurricanes in American history, Andrew, was the first tropical storm of 1992. Andrew did not become a Tropical Storm until August 16th, making it one of the latest "first storms" of a single season, and one of only three Category 5 hurricanes to make landfall in the United States. 

Hurricane return rate along the East Coast and
Gulf Coast of the USA, courtesy of NOAA

DC Hurricane climatology: The above map shows the Return Period for hurricanes in the Atlantic Basin. The Return Period is the average number of years in between hurricane landfalls in a particular area, and as you can see, we have at least 12 years on average between landfalls in our area. In the immediate DC Metro, it's extremely rare to get winds of 74mph or greater from a hurricane itself. The Chesapeake Bay and the DelMarVa peninsula help insulate us; even with our proximity to the Chesapeake, we really can't consider Washington to be a coastal city because we are not right along the ocean. Once hurricanes make landfall, they lose their windspeed rapidly, and the worst of the wind is removed from a storm while it's over the DelMarVa. The Beltway can be thankful for this barrier of protection from tropical systems!