Hurricane Preventer: Saharan Dust
By: Marina Kobasiuk
Hurricanes need specific conditions in order to form and strengthen; generally this means higher ocean temperatures, warm and moist air above the water, and low wind shear so storms can stay organized and not loose the air masses that feed them. There are other factors as no weather phenomenon or condition exists in a vacuum, but these more prevalent ones tend to control much of hurricane development. Currently in this 2018 season though there has been a more unique occurrence that has been helping to keep the Atlantic quiet. That would be the clouds of dust carried from the Sahara in West Africa by winds moving towards the Americas.
These air masses are extremely dry, and while they’re not an uncommon event at all due to the Easterly winds in that region, the plume observed at the end of June was visibly larger than most on satellites. This larger mass of dust has likely been preventing larger storms from forming as the dryer conditions lie above the moist layer that’s at the surface and restrict convection and keep storms from intensifying. This is such a regular occurrence in the region that the term “Saharan air layer” is used to refer to the section of atmosphere all this heat and dust resides in. This influx of particles is also tied to air quality in the southern united states and the Caribbean with the dry, hot, and dusty air interacting with local air masses and adding to pollution problems.
In May, NOAA predicted that the Atlantic was likely to see an “near or above normal” hurricane season, but this hasn’t come to pass exactly. There have been relatively less storms and even fewer have intensified enough to be named. The conditions at face value should be favoring storms as sea surface temperatures are higher and broke records in June. The month was the fifth warmest June ever for the planet, and the sea surface temperatures when averaged made it the sixth warmest June ever for the sea surface. Ocean temperatures of this sort should be ripe for severe weather development, but the dust plumes that were also pushed into the atmosphere at the same time seem to be contributing to the lack of storms and keeping this available energy under wraps. But while this is the current pattern now, as the dust clears and ocean temperatures continue to rise with the rest of summer, the chance of a hurricane becomes higher. The later half of the season is normally the more active and intense part to begin with and this effect might only be a break before the 2018 shifts once again.
Summary: The recent weeks the Atlantic’s hurricane season has been going slowly, and while things can change, dust plumes from Africa could be keeping the effects of a warm ocean in check for now.