The tropics are back on pause. The dust won.
Not that it was very far off pause, but the disturbance that was given a slight chance to develop in the middle of the tropical Atlantic has given up on trying to organize. It is now expected to move through the Caribbean islands around Sunday and Monday as a moisture surge. Some gusty tropical squalls are likely, especially at the higher elevations.
It’s not 100% clear why the disturbance didn’t develop, and the tropics are so quiet. The broad swoop of Saharan dust that has spread from Africa all the way to the southeastern U.S. is part of it. But robust disturbances that track far enough south of the dust can often moisten a patch of atmosphere enough to get going, so there’s likely more going on.
The water in the tropical Atlantic is now quite warm. On average, the upper-level winds are conducive for development. And the current La Niña condition in the tropical Pacific is normally very conducive to more Atlantic storms forming. But so far, the atmosphere overall has been just hostile enough to limit development.
The Saharan dust is a big part of it, but there are likely factors in the overall circulation that have contributed. Also, a tongue of cool water just north of where the most recent disturbance was tracking might be a contributing factor to the hostile environment.
The long-range computer models are not showing much development until the latter part of next week - if then. We don’t make definitive forecasts much beyond five days because we’ve all seen systems spin up quickly near the heart of the hurricane season when atmospheric conditions suddenly become conducive for development.
Typically, the odds of storms developing increase dramatically around August 15th to 20th. Obviously, that time is right around the corner.
On average, the Saharan dust is receding by now, the ocean water is warm, and the jet stream moves far to the north into its summertime posture. But there are more factors in play.
For now, we can be happy with the apparent delay in the start of the busy part of season. Though we can’t rest yet. The conditions still seem quite conducive for an above average balance of the season,