Atlantic Wave Train Getting a Late Start

Two tropical waves could develop in the coming week but neither is a concern for the U.S.

As we’ve been advertising since early last week, the Atlantic is poised to pick up the pace as we round out September.

The leading disturbance that we’ve been tracking – a tropical wave designated Invest 92L by the National Hurricane Center – is on track to become a tropical depression or named storm in the coming days while a second tropical wave exiting Africa today could develop by the weekend or early next week.

Neither system is expected to pose any threat to land in the coming week, but models indicate 92L could grow into a powerful hurricane as it rounds the western side of the subtropical high-pressure steering, perhaps posing a close call or direct threat to Bermuda come mid to late next week.

Probability of the center of 92L or what comes of it passing to within about 100 miles of a given location through next week from our major global forecast models. Models agree the system will develop and curve northward and away from the U.S., but it’s too soon to know whether it’ll pose a direct threat to Bermuda. Interests in Bermuda should monitor the forecasts in the week ahead. Credit: Tomer Burg/University of Oklahoma

Interests in the British Overseas Territory will want to continue to monitor the forecasts for 92L. The next name on the list is Gabrielle.

No problems for the U.S. for now

The usual African wave train – the conga line of tropical waves exiting Africa that hits its peak by late August and September – is a little late to the party this season. As we’ve explained in previous newsletters, the Atlantic has so far struggled with bouts of dry and sinking air.

The upshot of this late start is the Bermuda/Azores high, which can steer would-be hurricanes – the famed Cabo Verde hurricanes – toward the U.S., is in a weaker place than it is at the start of the month.

Average strength and position of the Bermuda/Azores high at the start of September. Deeper blues indicate higher/stronger mean sea level pressure.

Average strength and position of the Bermuda/Azores high at the end of September. Lighter blues indicate lower/weaker mean sea level pressure.

With high-pressure steering not reaching as far west as in early September, systems have a tougher time making it clear across the Atlantic.

This will be the case with 92L and likely the system behind it as they find escape routes north into the Atlantic and away from the U.S.

Of course, Bermuda is often in the crosshairs of hurricanes throughout September and will want to continue to check back on the trends. Most intensity models are bullish on 92L’s future, strengthening it into a hurricane as it rounds the subtropical high next week.

Intensity forecasts for Invest 92L through next week. HCCA and IVCN, our better performing intensity aids, suggest it’ll become a hurricane by next week as it turns northward. Credit: cyclonicwx.com

The trailing system will likely follow in 92L’s footsteps, staying north of the Caribbean islands and doesn’t look like it’ll make it too far before also curling into the open Atlantic.