For the last 10 days, meteorologists watching activity in the Atlantic Basin have singled out the Saharan Air Layer (SAL) as the reason behind the tranquil waters being experienced this week.

Despite sea temperatures being favourable, repeated waves of Saharan dust are negatively impacting the development potential of weather disturbances, as countries continue to keep a watchful eye nearly two months into the 2021 North Atlantic Hurricane Season.

The theory is supported by data collected in a 2006 study, which suggests tropical storms, and their larger, more dangerous hurricane counterparts, get incrementally weaker in the presence of the African dust.

Researcher Jason Dunion, speaking with the Earth Observatory run by the US-based National Aeronautics and Space Administration (NASA), surmised dust storms like the Saharan Air Layer have three factors that lead to storms eventually fizzling out.

“One, it’s got super-dry air. Hurricanes don’t like dry air in the middle parts of the atmosphere, and that’s exactly what the Saharan Air Layer has. A Saharan dust storm also has a very strong surge of air embedded within it, called the mid-level easterly jet, that can rip a storm apart that’s trying to develop. We call that vertical wind shear. And then the third piece is all this dust.”

Dunion was among 100 meteorologists and researchers who participated in the NASA African Monsoon Multidisciplinary Analyses (NAMMA) campaign—a joint effort between NASA and the National Oceanic and Atmospheric Administration (NOAA), during the North Atlantic Hurricane Season of 2006.

Researchers think the dust itself suppresses cloud formation, playing a role in preventing tropical waves from becoming more intense.

In fact, during the biggest wave of Saharan dust in decades last year, the phenomenon was responsible for ‘stunting’ the growth of Tropical Storm Gonzalo.

The Trinidad and Tobago Meteorological Service (TTMS), tracking the approach of Gonzalo, had anticipated the storm to have intensified into a category one hurricane.

However, in its afternoon advisory on July 23, 2020, the system remained at tropical storm strength, with maximum sustained winds of 95 kilometres/hour.

This, the TTMS said, was due to Gonzalo’s interaction with a plume of Saharan dust in the vicinity of the eastern Caribbean at the time.

In this current hurricane season, Jamaica also witnessed the impact on Saharan dust as a plume was responsible for weakening a tropical wave approaching the island at the start of July.

The tropical wave, which was just ahead of Hurricane Elsa, had its thunderstorms neutralised by the dust cloud, and lead to weather sleuths at the Jamaica Meteorological Services reducing rainfall projections.

• Unlikely hero? Saharan dust breaking up weak tropical wave entering Jamaican waters

Today, and nearly a year later, weather sleuths at the Florida-based National Hurricane Center (NHC) have declared there was no tropical storm activity expected within the next 48 hours—an outlook repeated since last Monday.

It seems that while the bothersome Saharan dust plume has proved to be a nuisance and health concern for humans, storms dislike them just as much as we do.

• See related article: Saharan dust plume creeps closer to Jamaica; more of the Caribbean under its influence