The giant tropical disturbance in the eastern Atlantic is finally showing signs of organization as it’s rapidly approaching the Caribbean islands.
When a system is spinning as good as this one is, it usually develops into a tropical depression or tropical storm. The National Hurricane Center is counting on that, saying it likely will consolidate into a tighter, organized system. Satellites are already measuring winds of over 40 mph, so this one will likely jump right to Tropical Storm Isaias if organization continues.
The circulation is currently oblong, huge and there is a lot of dry air around it. These are all factors that normally slow or sometimes completely stifle development.
But even though it’s taking a while, the consolidation process finally appears to be happening. Hurricane hunters will examine the system close up this afternoon, and we’ll know if a reasonably circular, organized circulation has developed.
The whole system is speeding toward the northeastern Caribbean islands. The circulation, whatever shape it’s in, should start affecting the islands later today with gusty winds and heavy rain – especially in the northeastern islands. The bad weather will spread over the Virgin Islands then Puerto Rico tomorrow and tomorrow night.
As the system tracks farther and farther north, it gets deeper into the Saharan Dust belt. There will be a battle between the disturbance and the dust. Unless enough moisture can wrap around an organized circulation to keep the dry air out, the dust should help keep the system from getting super strong.
The system is being drawn to the north because the blocking high pressure system has backed off for now, so there’s a gap around its western nose.
On the current schedule, the storm will be in the vicinity of Florida, the Bahamas or Cuba over the weekend. At that time, the upper-level winds are forecast to become somewhat more hostile, and the computer forecast models generally show the system weakening a bit or in some cases falling apart.
But forecasting how strong the storm will be with all of factors in play is a bit of a crap shoot. The system is going to deal with dry air, the hostile upper winds and the mountains of the Caribbean islands. So we have to say vigilant.
The computer forecast models generally agree that Isaias won’t be terribly strong. But a couple of days ago, the story was the opposite. Many models were showing a hurricane. So we have to be sure the tempering factors stay in place.
For now, there’s nothing to do but stay informed.
It looks like the next disturbance in line will be forced to stay on a southern track. Dry air is forecast to make its life difficult as it heads to the west, at least for now.
No other systems of note are expected to develop this week.