Atlantic hurricane season on pause, but it likely won’t last

After starting hurricane season 2021 at a breakneck pace, the oceans look to simmer over the next few weeks, with little in the way of tropical activity in the Atlantic through the end of July. Looking at the atmosphere offers clues to tell us that won’t last, however, with a quick uptick in activity likely in the cards as we head into August.

After last year’s record 30 named storms in the Atlantic, which included 14 hurricanes and a record-tying seven major hurricanes, the hyperactive stretch has already continued into 2021. Elsa, which lashed the Florida Panhandle and East Coast as a tropical storm last week, marked the earliest-forming fifth-named storm on record.

For now, that busy period has temporarily reached a pause, with the National Hurricane Center declining to highlight any areas to watch on its latest tropical weather outlook. We expect the pause to continue for a while before the atmosphere reverses course, perhaps dramatically, in August.

A number of factors are impeding tropical activity. To begin, the atmosphere isn’t favorable for organized convection, or shower/thunderstorm activity, that would be needed to seed a tropical system. That’s because of hot, dry air at the mid-levels blowing in from the east. What’s known as the “Saharan Air Layer,” or SAL, which also appears on satellite as a brown haze laden with sand and dust, squashes attempts of near-surface air to rise. Without widespread rising air, you can’t get a tropical storm or hurricane.

Even if one did form over the Atlantic’s “Main Development Region,” or the zone within which many of the more intense hurricanes form well east of the

Lesser Antilles, it probably wouldn’t remain intact long. There’s a belt of strong wind shear, or a change of wind speed and/ or direction with height, over the central tropical Atlantic. Those changing winds with altitude would tear apart a fledgling storm and disrupt the circulation and organization of anything that had already manifest.

Moreover, widespread sinking air is present over the Atlantic, marking one more hurdle that any tropical cyclones would need to overcome.

That unfavorable recipe for storms looks to remain dominant through the end of July, but there are signs that August could be a bit different. Already, the ocean is replete with fuel to sustain more significant storms — much of the central Atlantic is unusually mild, though there are some comparatively cool spots along the periphery of the Gulf of Mexico — and the waters will continue to warm beneath the summer sun. In two to three weeks’ time, meanwhile, the atmosphere could begin to awaken.

Moreover, steering currents over the Atlantic are concerning. Computer models predict a lobe of high pressure to become established over the northeastern United States, Nova Scotia and the Canadian Maritimes. That could help to suppress tropical systems southward, forcing them to continue barreling westward toward the United States rather than turning north earlier over the open Atlantic Ocean.

Based on current model predictions, storms that form will have a greater likelihood of being steered toward populated land masses.

Phil Klotzbach, a tropical weather researcher at Colorado State University, recently increased his Atlantic seasonal hurricane forecast from 17 to 20 named storms.