TAMPA, Fla. — As we head toward the end of the six-month-long hurricane season, we have another named storm.
- November storms more common than expected
- On average, named storms occur in Nov. every other year
- MORE weather blogs from our experts
Tropical Storm Sebastien has formed in the middle of the Atlantic. It is weak and will dissipate within a day or two.
November storms, although they seem unlikely, are more common than you may think.
There is a reason that hurricane season includes November. In fact, looking back at data over the last 50 years, 24 years had at least one named storm in November. So, on average, a named storm occurs in November every other year.
In analyzing the data over the last 50 years there are some things that stand out.
First, there appears to be no connection between the incidence of a November named storm and the frequency of storms during that season. There have been very active seasons with no November named storms. Consequently, there have been very quiet seasons with one or even two named November storms.
Also of note is that the overwhelming majority of named storms in November never affected land. Most occurred in the middle of the Atlantic Ocean.
The seasons that had named storms that affected the United States or Central America had later occurrences and frequency of October into November cold fronts. In other words, more than likely, there was less wind shear in the Caribbean and the water temperatures in the Caribbean, Western Atlantic, and the Gulf of Mexico was warmer and thus able to support tropical development.
An interesting tidbit is the incidence of “subtropical” storms. Prior to 2002, subtropical storms didn’t even get names. So, prior to 2002, there were no occurrences of named storms that since 2002 would have otherwise been classified. But, looking at the data, from 1969 through 2001, there were at least half of those years that had a subtropical storm in November.
It is simply that they weren’t named prior to 2002. Also, with respect to subtropical storms, since 2002, there have been an average of two each year that have received names, thus increasing the long term named storm averages.
There were some very notable absences of named storms in multiyear periods. There was a stretch of four straight years in the 1990s without a named November storm and eight straight years in the 1970s without one as well.
With respect to November hurricanes, of the 24 years that had a named storm or more during November, 14 of those years had at least one hurricane during November.
Finally, some other tidbits. In two of the years with no named November storm, those seasons had named storms after the hurricane season in December. And six of those years with a named storm in November had more than one. Those years were 2007, 2005 (which also had a storm in December), 2001, 1994, 1984, and 1980.