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  • Writer's pictureBryan Norcross

Watching the Atlantic just in case

The flurry of excitement the last day and a half about the large tropical disturbance in the far eastern Atlantic has largely died down. The computer forecast models that got people jazzed are no longer predicting much to occur with the large tropical disturbance near Africa.

The National Hurricane Center is still giving the disturbance a slight chance of becoming at least a tropical depression on its trek toward the Caribbean islands over the next 5 days. But the system is plowing through a big plume of Saharan Dust, and the ocean water below is quite cool – both of which are natural inhibitors to organization.

If a disturbance’s circulation ingests some of the dust, the dry air can throttle development. This tropical disturbance is quite large, however, and sometimes a big system contains enough moisture and enough of an envelope to hold off the dusty air. But even if it did that, the ocean water would still be providing only low-octane fuel for the system.

The odds are low that this disturbance will be able fight off the negative factors and significantly develop, and even if it gets a circulation and is designated a tropical depression, it appears that hostile upper-level winds will come into play when the system reaches the Caribbean, which would seem to prohibit significant further development.

This situation is a prime example of how important it is to ignore the premature doomcasting on social media.

One and only one run of the European computer forecast model developed the system. Then it backed off. One run of the American GFS model developed it a bit. These are excellent computer forecast systems – state of the art, in fact – but the rule is: Wait for consistency in a given model, and especially in multiple models, to predict something unusual. Which a significant storm coming out of the eastern Atlantic in June would be.

The fact to note from this situation is that robust disturbances are developing over Africa again this early summer. There is no reason to think that won’t continue, so we should expect an active tropical Atlantic when we get to August and September.

The tropical ocean water is cooler than last year, however, so in spite of the vigorous disturbances developing over land, they will have less fuel to work with this year, if the water-temperature trend continues.

We’ll keep an eye on the big east-Atlantic disturbance as it heads west over the next week or more. High pressure sprawled over the ocean is forecast to get quite strong, which should keep systems, including this one, to the south for the foreseeable future.

Elsewhere, the little system we were watching as it approached the southeastern Caribbean islands is passing over the islands today. It’s barely visible on the satellite, but may still prompt a few tropical downpours with gusty winds. We will have to watch it next week as it moves into the extreme southern Gulf of Mexico and joins with the broad low-pressure system over Central America.

In general, the tropics are fairly calm, but as always, we’ll keep an eye on the tropical ocean.


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