Another mostly tranquil week in the tropics

Despite the Madden Julian Oscillation or MJO – the big month-to-month driver for storminess in the tropics – landing in a more conducive configuration for tropical activity this week, the primary disturbance we’re tracking over the eastern Atlantic appears unlikely to take advantage of this MJO pulse, the first we’ve seen in the Atlantic since middle June.

Earlier forecast models that indicated the potential for slow development have gradually backed off the idea, as dry and stable air envelop the westward-moving disturbance.

Several factors will impede development with the eastern Atlantic disturbance this week.

First, tropical disturbances emerging from Africa farther north – like the one we’re tracking this week – tend to be less successful developing early on over the eastern Atlantic.

This is largely due to drier and more stable conditions farther north near Africa which limit storminess near these disturbances.

Additionally, strong disturbances like the one we’re following often pull dry air southward and out ahead of their paths, which creates a less favorable environment for organization.

Our forecast models show this scenario, with dry air spiraling inward toward the disturbance in the days ahead. The upshot will be low prospects for development, at least for the next several days.

While some 60 to 70 percent of our tropical depressions, storms and hurricanes originate from these disturbances moving off Africa every three to five days, only about six percent of the 30 or so that typically roll off Africa between July and September each season actually form this far east in the Atlantic.

So the odds are naturally working against this one, especially in July. Nevertheless, we follow these disturbances more closely this time of year because they can reignite as they track farther west in the Atlantic.

For now, the eastern Atlantic disturbance should lay low, with no other areas of potential development on the horizon in the Atlantic this week.