2013 Hurricane Season: Sometimes “We Don’t Know” Is the Best Answer


The Atlantic Multidecadal Oscillation (AMO) average value in Jan to March since 1948 – I looked at this earlier this season to project what the 2013 season may look like.

Back at the peak of the 2013 hurricane season, in a newsletter article for Stormpulse.com, I outlined why I thought activity could pick up as the second half of the season got underway

Like most experts at the time, I expected the season to observe at least a few more hurricanes and at least two major hurricanes in the tropical Atlantic. However, only one additional hurricane formed (making the seasonal total = 2) and we are on track to not see a major hurricane in the Atlantic for the first time since the Atlantic flipped into “active” mode after then 1994 season.

Several meteorologists have been chipping in explanations as to why things have been so quiet. Reasons cited have been:

1. Lack of mid-level moisture during the peak of the season
2. Unusually strong upper-level winds
3. Continued outbreaks of African dust spreading across the Atlantic

Still others are trying to find a link between the warming climate to less storms, even though some of the same scientists were trying to link the busy 2004 and 2005 hurricane seasons to the same cause.

Obviously, it can’t be both. A warming planet can’t cause more hurricanes in the Atlantic one year and still be responsible for quiet seasons too (unless, somehow, the global temperature gets to “choose” which seasons are busy).

However, one explanation seems to be missing from the debate. The principal of Occam’s Razor (which has an entire, well written analytics blog dedicated to the idea) states the simplest solution, in the absence of compelling evidence to the contrary, is most often the best available solution.

The Atlantic basin shows the most year to year variability of all of the major hurricane producing basins in the world. Water temperatures were very warm this year, pressures were low in the main development region (MDR) and we had two tropical storms in the deep tropics in July. These are usually indicators of a very busy hurricane season – but something else has kept the storms away.

Unless someone is able to come up with proof beyond speculation, my belief is this year is simply a case of unexplained variance, which said another way is “we don’t know“. We saw several storms develop close to land, which is impossible to anticipate in seasonal forecasts, and other factors in other basins, such as the cold Pacific, may have added stability to the tropics.

We have a very small sample of years to work with as a base period for seasonal forecasting, which is like taking a temperature sample for 45 minutes from one location on one day and trying to project, based on that data, temperatures for a location for the next 10 years.

The validity of even issuing seasonal forecasts is a different discussion for a different blog. However, for this Atlantic season, I think more scientists should admit that “we don’t know” is often the best answer instead of guessing.

Mike Watkins
Hurricane Analytics

Have a better explanation? Send it to me!

About Michael Watkins

Mike Watkins is the founder of Hurricane Analytics, a private organization specializing in data visualization and predictive analytics, with a special focus on tropical meteorology. They analyze complex meteorological data and communicate that information in easy-to-understand terms, to help clients prepare and anticipate the disruptive impact of Atlantic hurricanes.