12 April 2018

Four names retired from 2017 hurricane season, the most since 2005

In a recent meeting of the World Meteorological Organization (the agency that decides on tropical cyclone names), four names were retired from the 2017 list: Harvey, Irma, Maria, and Nate.  There is a series of six name lists that rotate every six years, so the same list we had in 2017 was also in place for 2011, 2005, 1999, etc, and will be used again 2023.

However, names can be permanently retired from use and replaced with different ones if the storm associated with that name was "so deadly or costly that the future use of its name on a different storm would be inappropriate for obvious reasons of sensitivity" (NHC). The new names in the 2023 list will be Harold, Idalia, Margot, and Nigel.

2017 was impressive in that more than three names were retired from a single season... the other such seasons were 2005 (5), 2004 (4), 1995 (4), and 1955 (4).

Irma was retired on its first time on a list (it replaced Irene from 2011).  The other names that were retired on their list debut were Igor (2010), Ike (2008), and Michelle (2008).  [Note that Joaquin first appeared on a list in 2009, but did not get used... it was retired after its first use in 2015.]

Having yet another retired "I" name amplifies that letter as the most commonly-retired (11 times)... "C" is in second place at 9 times.

And, not surprisingly, the most frequent month for a retired storm name to have occurred in is September.

Finally, although Category 5 storms are the strongest, they are rare... so the majority of names that get retired are from storms that peaked at Category 4 intensity.  But, notice that "major hurricanes" (Category 3 or higher) account for 84% of all retired names.

05 April 2018

April outlook for 2018 Atlantic hurricane season activity

As they have done every year since 1984, Colorado State University (CSU) has released their initial predictions for the upcoming Atlantic hurricane season. Phil Klotzbach and I take a look at the numbers in this post on the Washington Post's Capital Weather Gang blog: