The Atlantic hurricane season peaks on September 10.
Enlarge / The Atlantic hurricane season peaks on September 10.

This year's Atlantic Hurricane season has been unconventional.

Everyone from the US agency devoted to studying weather, oceans, and the atmosphere predicted an above-normal season for hurricanes.

A 65 percent chance of an above-normal season, a 25 percent chance of a near-normal season and a 10 percent chance of a below-normal season were predicted by the forecast by the National Oceanographic and Atmospheric Administration. The expectation that La Nia would persist in the Pacific Ocean led to the predictions. The storms have not come in large numbers.

All quiet

The Atlantic has had five named storms, which is not all that far away from normal activity, as measured by the average of the last two decades. The National Hurricane Center gives names to tropical storms and hurricanes in the Atlantic.

When we look at the duration and intensity of storms, we can see that the disparity is more significant. The value of 28.6 is less than half of the normal value through Saturday.

The most striking thing about this season is that we are at the peak of the storm season, and there is nothing going on. Although the Atlantic season begins on June 1, it starts slowly, with a storm here or there in June, and sometimes a quiet July before the tropics get rolling in August. In the 14 weeks prior to September 10, about half of all activity takes place, and then the majority of storms spin up before the end of October.

We're not seeing any signs of a madcap finish in the Atlantic basin at the moment. The National Hurricane Center is keeping a close eye on a tropical wave that will move off the African coast into the Atlantic Ocean. None of the global models anticipate much from the system and it has a low chance of development. There is a 20 to 30 percent chance of a tropical depression developing in the Atlantic during the next 10 days.


The tropics are usually lit up like a Christmas tree this time of year. September is a good time to see some of the lowest wind shear values because the Atlantic is still warm from the summer months.

What went wrong

At least so far, what has happened this year has caused a quiet season. A detailed analysis will have to wait until after the season, but to date we have seen a lot of dust in the atmosphere, which has prevented the formation of storms. The upper-level winds in the atmosphere have been hostile to storm formation.

It is important to understand that the forecasting of actual storms is different from the forecasting of seasonal activity. The seasonal forecasting is still evolving. Predicting hurricanes months in advance is not an established science.

The Atlantic tropics are extraordinarily quiet for the peak of hurricane season.
The Atlantic tropics are extraordinarily quiet for the peak of hurricane season.

The tracks of tropical storms and hurricanes have already been predicted by the forecasters. Our ability to predict strength or weakness has improved. The National Hurricane Center's track forecast accuracy has improved since Hurricane Andrew devastated Florida in 1992.

More powerful supercomputers, a better understanding of the physics of tropical systems, and better tools for gathering real-time data about atmospheric conditions are some of the reasons why this is happening.