Analysis of December Atlantic storms

[Hurricanehink]

The season ended on November 30, but if the calendar decides to produce a new storm before the ball in Times Square reaches 0, then it still counts as part of this season's total. Per Wikipedia's List of off-season Atlantic hurricanes - http://en.wikipedia.org/wiki/List_of_off-season_Atlantic_hurricanes - there have been 13 tropical cyclones that formed in December, including one in 1822. Of the 12 remaining, two were tropical depressions, which leaves 10 such tropical storms/hurricanes in the best track, or a 6.25% in a given year. The average number of storms in those ten seasons is 16, although Zeta from 2005 skews it upward. Removing that leaves an average of 15. One thing to caution, however, is that only 9/10 storms does not mean much in terms of data analysis. In addition, both 2003 and 1887 had two storms that formed in December, both in a short time span.

With so few storms, I expanded my analysis to include storms that formed in November and were still tropical cyclones in December. There were 21 storms on Wiki's list, and, when removing the tropical depressions and the 1822 storm, I have 18 storms. The average season activity is 15 storms, but is again bolstered by two 2005 storms. Removing Epsilon and Zeta gives 14, which is still above-average by all definitions.

While it seems that December storms are more likely to happen in above-average seasons, that doesn't necessarily mean that an above-average season will have a December storm. Of the top 22 most active seasons (those with 13 or more storms), 1933, 1995, 2010, 1969, 1936, 2008, 2000, 1990, 1949, 1950, 1971, and 1996 (12/22) did not have a post-season storm. We will see as the re-analysis project progresses on how this data changes, but I just wanted to throw this out there.