Tropical Storm Gonzalo could strengthen into a hurricane

Tropical Storm Gonzalo formed on Wednesday in the central Atlantic Basin, about midway between the West African coast and the islands of the Lesser Antilles. At first it was expected to stay a tropical storm, but the National Hurricane Center has now revised its forecast to increase the chances it will become a hurricane Thursday night or Friday, before it approaches the southern Caribbean by the end of the week.

As of Thursday morning, the National Hurricane Center said a hurricane watch is in effect for the islands of Barbados, St. Vincent and the Grenadines. Gonzalo had maximum sustained winds of 65 mph and is moving to the west at about 14 mph. The storm is forecast to reach the southern Lesser Antilles by Saturday.

While the future track of Gonzalo appears fairly straightforward, the intensity is very uncertain. The computer models meteorologists use to forecast these systems are split into two camps. The global computer models, like the well-known European model, show the system weakening as it reaches the Lesser Antilles and Caribbean. But specialized tropical models are more robust, showing the storm strengthening to a hurricane and remaining that way through the next 5 days.

There is no telling which group of models will prove correct, but so far the tropical models seem to be doing a better job. That is partly because Gonzalo is a small system and these tropical models are able to better analyze smaller-scale features.

Often small systems can shield themselves from the surrounding environment. In this case there is dry air around the system. The stronger tropical models keep the influence of dry air to a minimum by cocooning, or protecting, the storm, allowing it to strengthen. The larger-scale models allow the dry air to feed in, weakening the storm’s structure and thunderstorms.

Regardless of what happens next, Gonzalo is already one for the record books. It is the earliest 7th named system of any Atlantic season on record.

And by the end of the week there may be another named system, this time much closer to home. The National Hurricane Center is monitoring a broad area of low pressure with a disorganized cluster of storms over the central Gulf of Mexico. The chance of development has now increased to 80%, with a tropical depression or tropical storm is likely to form by Friday. Either way it will likely bring gusty winds and heavy downpours into Texas by Friday and Saturday.

One reason for the active season so far has been unusually warm waters in the tropical Atlantic, and that seems to be continuing. Gonzalo marks the beginning of the second phase of hurricane season, which is called the Cape Verde season. This is when systems in the main development region, in between Africa and the Caribbean, flare up. It usually occurs in early to mid August, but this season it is starting several weeks early. This is partly due to near historic warm sea surface temperatures in the main development region.

Also, Gonzalo is forming very far south compared with most other tropical systems.

Its prospects beyond the weekend are very uncertain right now. But there is at least some chance it will remain a hurricane in the Caribbean and if so, this storm will need to be watched closely to see if it makes the turn north towards the U.S. or moves west into Central America.

After Gonzalo, computer models are showing another system with a good potential for development now emerging off of Africa. While its fate is uncertain, what does seem certain is that an active couple of weeks — and likely hurricane season as a whole — is now upon us. This is in line with all of the seasonal forecasts from various organizations warning it’s likely to be one of the most active hurricane seasons on record in the Atlantic.