We’re following two disturbances across the tropical Atlantic at the moment, but Tropical Disturbance #1, the one closest to the Caribbean islands, is most likely to develop into at least a tropical depression and is heading in the general direction of Florida.
The computer forecast models are in unusually good agreement about the system’s path this week - over or near the large Caribbean islands and toward the Bahamas and Florida. The open question is whether the disturbance will organize and how strong it might become.
The consensus is that Tropical Disturbance #1 will arrive in the vicinity of South Florida around Friday or Saturday at least as a strong moisture surge with some gusty downpours.
It would seem the disturbance has a hard road ahead of it. While the upper-level winds appear reasonably conducive for development, the system is plowing directly into a batch of Saharan air. Some of the dry air seems likely to wrap into the circulation, which would limit the thunderstorms that could form around the center, a requirement for significant strengthening.
In addition, the consensus track of the latest computer forecast models takes the system over or near the mountains of Puerto Rico Tuesday into Wednesday. Heavy rain and gusty winds are expected there. Wednesday into Thursday the system is forecast to interact with the tall mountains in the Dominican Republic and Haiti. Again, very heavy rain and flooding are possible.
If the disturbance ends up tracking over or near those mountainous islands, it diminishes the chance that a well-organized circulation would emerge in the Bahamas or around Florida or Cuba at the end of the week.
In addition, when the system gets near Florida, an upper-level disturbance will come into play, which could limit potential development, depending on how the two systems interact.
Nothing about the forecast is certain, of course. All forecasts for undeveloped or just developing systems are subject to large errors. We’ll have to see how things develop over the next few days. If an organized circulation emerges, the computer forecast models would likely become more reliable.
The National Hurricane Center is alerting residents of Puerto Rico and
the Virgin Islands that tropical storm watches or warnings might be required at any time if Tropical Disturbance #1 suddenly organizes and appears as if it could become Tropical Storm Fred before reaching those islands.
Note that the red area on the NHC’s map looks like a typical forecast cone, but it’s not. This is the area within which a tropical depression or tropical storm would likely form sometime within the next 5 days, if it forms at all. The length of the area is in recognition of the uncertainty given the negative factors involved. But it would only take a patch of conducive atmosphere and open water to allow the circulation to consolidate and organize into a depression or low-end tropical storm.
There are no indications at this time that this system will become a strong storm, but given the uncertainties around just-developing systems, we have to watch carefully until we’re sure.
Disturbance #2 is looking very weak. The National Hurricane Center is still only giving it a slight chance of developing into at least a tropical depression. The computer forecast models generally show it moving west and falling apart or getting pulled into Tropical Disturbance #1′s circulation.
Long-range computer forecast models show another system will soon move off Africa into the Atlantic. It looks like the hurricane season is picking up right on schedule.