• Bryan Norcross

THE TROPICAL DISTURBANCE IN THE EASTERN ATLANTIC IS CLOSE TO DEVELOPING INTO A DEPRESSION

There is still a profound lack of certainty about what’s going to happen with the two tropical disturbances we’ve been watching, although one is closer to developing.


Disturbance #1 is not expected to organize for another two or three days, until it reaches the extreme western Caribbean Sea. Disturbance #2, however, will probably organize into a tropical depression sooner. It’s on the cusp now. But it will be fighting dry Saharan air and marginally hostile upper winds.

We are watching Disturbance #2 closely because it is positioned in a part of the ocean that sometimes spawns storms that affect Florida.

The circulation that the National Hurricane Center is focusing on for development into a tropical depression or tropical storm is on the west end of a wide, elliptical area of disturbed weather. The circulation is strong and is finally consolidating. But dry air in the vicinity has been causing thunderstorms that develop to collapse or disperse, which has been keeping the system from meeting the criteria for a tropical depression. In addition, there has been a second prominent circulation embedded in the same broad disturbance, which has thrown a monkey wrench in the computer forecast models’ ability to track the center of the system.

Both inhibitors appear to be decreasing, so now the system can likely develop.

Assuming the disturbance continues to pull itself together into a single defined circulation, it will likely track in the general direction of the northeastern Caribbean islands. As it does, the computer forecast models anticipate that dry air will continue to nag the system for at least the next few days. In addition, an upper lever disturbance northeast of the islands is generating hostile upper-level winds. This marginal environment should keep the system from organizing quickly into a very strong system, if it develops much at all.

It has to be watched carefully however because sometimes a strong circulation can find a patch of conducive atmosphere and spin up quicker than expected over the warm tropical ocean. When it does that, it can pull in enough moisture to create a protective bubble, which can hold off the dry air. That doesn’t appear to be a likely scenario, but it’s not impossible.

At the end of the week and into the weekend, the system is forecast to be in the vicinity of the northeastern Caribbean islands, the Virgin Islands, and Puerto Rico. It may just be a gusty moisture surge at that point, or it might have organized into a tropical depression or tropical storm, but it’s not likely, based on what we know now, to be very strong.

Moving ahead, assuming a depression or storm is able to organize, and it is not torn apart by the tall mountains on the Caribbean islands, the atmospheric pattern near Florida may be more conducive for development. But that assumes a circulation makes it this far west early next week.

That’s a lot of ifs piled on top of other ifs, so the bottom line is, we have to wait a day or two and see if the system can overcome its immediate challenges and achieve a structure that will allow it to strengthen. Only then will computer model forecasts be meaningful. So far, they haven’t been, in part due to the multiple circulation centers in the broad disturbance.

For now, we can assume that some aspect of Disturbance #2, whether it’s mostly moisture or some sort of developed system, will be in the vicinity of Florida early next week. Again, there is no indication it would be a strong system at this time, but we can’t completely rule that out.


Disturbance #1 is a well-defined kink in the wind flow whose organization is also being impeded by a tongue of dry air. Its opportunity to develop should come in a couple of days when it reaches the western Caribbean. At that time, a dip in the jet stream will be plunging south into the Gulf of Mexico. If the disturbance can organize quickly and be far enough north, it could get scooped north into the Gulf. If it’s weaker or farther south, it’s more likely to track into the western Gulf toward Mexico or South Texas.

Because the exact location and intensity of the system isn’t knowable at this time, there is no reason to speculate on which way the system might go. It’s another case where we have to see what emerges from the current hostile environment before we can make a reasonable prediction.

Interestingly, about Friday, both of these systems should have either cleared these initial obstacles or not. Stay tuned.

The third disturbance is quite large. Tropical Disturbance #3 is just about to emerge from the African continent. The atmospheric conditions over the eastern tropical ocean appear marginal at this time, so it’s given a lower chance of development over the next five days.

© 2019 by Bryan Norcross Corporation

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