Forecast Models Advertising an Active Start to September

Models suggest two candidates for development next week, including a growing threat to the Caribbean

Two Atlantic systems that we spotlighted in Wednesday’s newsletter are gaining support for development next week as forecast models trend toward an active start to September.

The tropical Atlantic has been in a rain delay since Hurricane Ernesto’s departure 9 days ago, but the players are back on the field and, based on forecast trends, it appears official play will resume next week.

System approaching Caribbean early next week bears watching

The first system we’ll be tracking is a disturbance that’s currently over the central Atlantic and embedded within a broad strip of storminess draped across the Atlantic extending from Africa known as the monsoon trough.

By late weekend the disturbance is expected to break free of its monsoon trough umbilical cord as it moves westward in the general direction of the easternmost Caribbean islands. Models indicate the possibility of slow development east of the islands, with the threat of an organized tropical system (tropical depression or tropical storm) moving through parts of the Lesser Antilles sometime late next Monday into Tuesday.

Low pressure tracks through next Monday evening (September 2^nd) from the overnight run of the European model ensemble system. Models have trended toward more development with the system since yesterday. Credit: Weathernerds.org

We’ll have to give the system time to come together before having a better idea of how organized it could get before reaching the islands, but those with interests in the eastern Caribbean should monitor the forecasts closely in the days ahead.

Beyond early next week, models show an increasingly conducive environment for the system to organize as it moves deeper into the Caribbean. Given the forecast trends, we shouldn’t be surprised to see a strengthening tropical system near or south of Puerto Rico, the U.S. Virgin Islands, the Dominican Republic, and Haiti next Wednesday and Thursday.

Odds of at least a tropical storm (39 mph winds or stronger) passing within about 150-200 miles of a given location next Wednesday and Thursday (September 4-5) based on the overnight run of the European model ensemble system. Credit: Weathermodels.com

Given the uncertainty in where the system ultimately tries to form, it’s far too early to speculate on any threat beyond the middle part of next week. For now, we’ll want to monitor its progress into next week.

Disturbance rolling off Africa could develop next week

A large tropical wave rolling off Africa into the Atlantic also shows promise for development into next week.

As we discussed in yesterday’s newsletter, this is the first vigorous tropical wave to splash into the Atlantic south of the Cabo Verde Islands in some time and beneath the drier, more stable air undermining the unusually north-positioned waves of the past few weeks.

Since the disturbance is large, it will likely take time to organize and won’t even make it to the central Atlantic until the middle part of next week. We have plenty of time to watch it.