• Bryan Norcross

THE TROPICS ARE HEATING UP AS WE HEAD TOWARD THE PEAK OF THE HURRICANE SEASON

The National Hurricane Center is focusing on two disturbances in the Atlantic between the Caribbean islands and Africa. Each has an opportunity to develop, especially toward the end of the week. This is all happening according to the book. Nominally, the peak eight weeks of hurricane season begin about August 20th, which is this Thursday.

The first disturbance we’re watching is a few hundred miles east of the eastern Caribbean islands. It is showing signs it’s trying to organize, but the upper winds are a bit hostile, which is stretching it out. It’s most likely to pass through the islands late today into tomorrow as a moisture surge with gusty squalls and some heavy rain.

In a few days, the disturbance will be in the western Caribbean. It has a better chance of finding a pocket of atmospheric conditions conducive for organizing and strengthening, although that’s not certain. Generally, the upper-wind regime is less than ideal. In any case, we will watch it toward the end of the week.


Well behind that system is another larger disturbance, which is still closer to Africa than the Caribbean, and it’s a bit farther south. This disturbance is still disorganized and mixed up with dry air, which is dominating the eastern Atlantic. In a few days, however, Disturbance #2 has a better chance of organizing.

Because this system is far to the south, we keep an especially close eye on it. Most tropical systems are going to want to lean to the right (bend to the north) at some point – an effect related to the spinning of the earth. When systems start farther south, if they develop, they are more likely to affect land just because they have to turn harder north to avoid it.

An unforecastable angle difference in its track, however, makes a huge difference in which land it affects, if it does. And it has a long way to go.

On the current schedule, the system will be in vicinity of the Caribbean islands late in the week, so it’s more than a week away from any effects in the Southeast U.S., if it makes it anywhere near here.

The rule of new systems applies: Forecasts for weak or developing systems intrinsically have higher than average errors.

So don’t look at long-range spaghetti plots or individual models. They will bounce around every few hours. They are only good for getting a rough idea when a system might arrive, broadly speaking, in the general vicinity.

Beyond these two systems, no other disturbances are expected to develop this week.