Enhanced satellite image over the eastern Atlantic. Blue coloring indicates high cold cloud tops. (EUMETSAT)

In the coming week, two new tropical weather systems could develop — one in the eastern Atlantic and, ominously, one in the northwest Gulf of Mexico — not far from Texas. Hurricane forecasters, like ourselves, will be monitoring these systems closely.

Eastern Atlantic storm potential

The system closest to becoming a named storm is positioned in the eastern Atlantic, just west of the Cabo Verde Islands and heading to the west-northwest. It has a very high likelihood of becoming a tropical storm in the next few days and will be a feature of continued interest as it heads west. On its predicted path, it would be near the Windward Islands next Tuesday.

Whether the storm passes over, north or south of these islands remains an open, yet important, question. Storms that pass to north of these island are more likely to curve away from the United States, although that’s not a guarantee.

Using large numbers of simulations, the United States’ GFS model (top) keeps the system weaker and farther north, while the European model keeps it stronger and farther south. These are generalities and long-range trends, not forecasts.


Deterministic and ensemble forecast tracks for AL93 over the next 10 days. (UAlbany)

The ocean environment over which the system is passing is expected to be favorable for development and intensification in the coming days. The ocean temperatures along its trajectory are between 81 and 83 degrees, the vertical wind shear — which disrupts development — is quite low, and the only potential impeding factor is dry Saharan air. The system is not embedded in a thick plume of dry air, but there is some to its north and west, and that could be a reason different models have different intensity forecasts over the coming seven to 10 days.


Satellite image of AL93 with areas of dry, dusty air indicated by yellow and orange coloring. (UW/CIMSS)

Should  this storm reach tropical storm strength, the next name on this year’s list of storms is Irma, following Harvey.

Potential Gulf of Mexico system

Models are also hinting at the potential for tropical cyclone development in the northwest Gulf of Mexico early next week. Both the U.S. and Euro models simulate a weak, but very wet, system over eastern Texas and Louisiana next Monday through Wednesday.

It is too soon to place much stock on these model runs, but the fact that both leading global models have something there around at the same time is disconcerting. We will be monitoring this closely.


Model forecasts valid next Wednesday morning from the ECMWF (left) and GFS (right). (tropicaltidbits.com)