Other than a brief scare with Hurricane Joaquin, 2015 went down as another relatively quiet year for hurricanes across the Atlantic. In fact, last year was the third year in a row with below normal tropical activity. So with the 2015 season well in the rear-view mirror, is the Atlantic Basin expected to see a rebound in 2016? Let’s take a look at some of the players expected to impact the upcoming hurricane season.
One of the major ingredients necessary for a tropical cyclone to develop and strengthen is very warm ocean temperatures. Currently, sea surface temperature (SST) anomalies across the North Atlantic are quite variable. Ocean waters just south of the Greenland are rather chilly, while SSTs off the East Coast are mainly above normal. In the eastern Tropical Atlantic, ocean temperatures are fairly typical. The biggest exception is right off the coast of Africa, where SSTs are cooler than usual. These negative anomalies are a product of predominately positive North Atlantic Oscillation (NAO). When the NAO is in a positive state, easterly winds across the region are generally enhanced. When this occurs, upwelling off the coast of Africa increases. This allows colder water to mix up to the surface and results in relatively cool SSTs.
Despite being a major story over the past year, the strong El Niño in the Tropical Pacific is rapidly diminishing. However, ENSO (El Niño Southern Oscillations) could continue to have an impact on tropical activity through the end of the year. Current long range model guidance points to the transitioning of El Niño to La Niña during the second half of 2016. La Niña is essentially the opposite of El Niño, as La Niña is characterized by cooler than normal ocean temperatures across much of the Tropical Pacific. While there is still some uncertainty, we currently favor La Niña conditions to emerge by either the late summer or the fall. This is important because La Niña promotes decreased amounts of wind shear across the Caribbean and central Atlantic. Overall this correlates with above average activity for the Atlantic Basin.
Image courtesy of International Research Institute of Climate and Society
So with La Niña favored to emerge, we certainly expect an increase in the number of tropical cyclones in 2016. When it is all said and done, we anticipate that the Atlantic Basin will experience slightly above normal activity this year. In fact, the 2016 season already got off to an extremely early start. Way back in January, Hurricane Alex reach peaked winds of 85 mph. Alex was significant as it was first hurricane to form in January since 1938.
The late summer and early fall will be the main time frame to watch. Not only is this the peak season, but this is when La Niña is most likely to start exerting its influence on the tropics. Other than La Niña, we will have to monitor SSTs across the Atlantic. If ocean temperatures across the Tropical Atlantic end up cooler than normal, this would act to counter La Niña and curb overall activity.
When looking at past La Niña seasons, an overwhelming majority of landfalling hurricanes have either hit the Gulf or Southeast coastlines. However, it is important to always stay vigilant, as Hurricane Irene caused major flooding and damage during the La Niña of 2011. With that said, Irene is not a strong analog, as the storm occurred while La Niña was already well established and not during an ENSO transition year like this one. Regardless, make sure to follow us here at WeatherWorks (on Facebook and Twitter!), as we will be watching the tropics closely all season long.
