Updated at 8:30 a.m. EDT
The atmospheric environment over the tropical Atlantic is unusually hostile this year. Disturbances that move off Africa run into dry air and a less-than-optimum wind profile as they trek west toward the Caribbean islands. Currently, the steering flow is weak, which increases the odds of hostile conditions impinging on the systems as they mosey along.
The large disturbance we have been watching appears to be developing something of a circulation, but thunderstorms are not well established. Likely dry air is wrapping into the system.
Another disturbance is due to move off Africa in a couple days. It is also likely to encounter excessive dry air.
The National Hurricane Center gives the disturbances a low chance of developing in the next five days. They are heading in the general direction of the northeastern Caribbean islands. If they survive that long, the projected environment closer to the Bahamas and the U.S. may be somewhat more conducive for development, so we’ll keep an eye on developments next week. Though forecasts for undeveloped systems that far in advance are fuzzy at best.
As a general statement, the ocean temperature and the upper-level winds continue to favor development, so a disturbance that can find a moist pocket of the atmosphere might well develop. Although it’s becoming likely, there are other factors at work beyond the dry air prohibiting development.
The atmosphere is a complicated system, and sometimes a number of little factors gang up to make the weather unexpectedly extreme or surprisingly benign. In any case, as we saw 30 years ago in the slow hurricane season of 1992, sometimes conditions can suddenly come together to produce an off-the-charts storm. So vigilance is required for a couple more months no matter how busy the hurricane season is overall.