• Bryan Norcross

Tropics stay quiet as Sahara Dust spreads across the Atlantic

The tropics are taking a July break, as they often do. Dry air in the middle levels of the atmosphere is dominating the ocean, and the computer forecast models say there’s more to come. For the most part, the dryness is related to dust from the Sahara Desert getting caught in just the right air flow to bring it our way.



NASA runs a special computer model that predicts how Saharan dust is going to propagate. It shows surge after surge of dry, dusty air spreading across the Atlantic over at least the next 10 days. That should keep the rain in Florida to more of the off and on variety, as opposed to the tropical deluges we had going on for a while.



The Saharan dust should also keep the tropics mostly quiet. Last year, despite an unusually long dust season, storms still found a way to form in late July. Disturbances found a patch of atmosphere that was moist enough for a system to spin up, at least briefly.


There’s a difference this year, however – the tropical ocean water is cooler. In fact, the water temperature in the main development region in the tropical Atlantic is about average to slightly below. Last year, it was quite warm, so the storms had more fuel to work with.


Tropical Storm Elsa came along even earlier than the 5th named storm in 2020, but now we’re falling behind. Thankfully! Last year, 6 storms had been named by this point.


The 9th named storm of 2020, Isaias, came along at the end of the month, which ended up being consequential all the way up the East Coast, of course. Then we got a pause in the record-break onslaught, only for it to return in full force in August. There’s no sign anything like that will happen again.


Saharan dust season generally starts wrapping up at the end of July, but can sometimes extend until about mid-August. So we’ll see.


For now, enjoy the drier weather. The long-range computer forecast models show nothing of interest in the tropics through the middle of next week, at least.