Although the waters have been relatively quiet straight through the Sept. 10 Atlantic peak, the conditions that have led to this lull are likely to change over the coming weeks, so the predicted active season can certainly still materialize. We are a little behind the forecast tropical activity, but if 2024 is any indication of what's to come, we could be in for another late-season surge of storms.

So why have things quieted down so much over the past three weeks? With meteorology, as with most things, there's never just one reason. One part of the equation is the Saharan dust and dry air coming off the African continent. This mass of very dry, dusty air in the atmosphere tends to suppress tropical development and intensification.

There's also been a bit more wind shear at higher levels of the atmosphere across the Atlantic. Wind at high levels can prevent the formation of thunderstorms, which are necessary for tropical activity, helping disturbances organize more effectively.

But most meteorologists agree that the main reason for the lack of tropical activity is likely connected to something called the Madden-Julian Oscillation, or MJO. This global atmospheric phenomenon circulates areas of high and low pressure around the planet in the warmer latitudes. If there's higher pressure over an area, tropical systems have trouble forming due to the sinking air. When low pressure returns to the same area, tropical systems can get organized as warm, moist air rises and condenses into storms.

When we saw Hurricane Erin form, low pressure was present over the Atlantic. This helped Erin rapidly intensify into a Category 5 storm. But since then, the MJO has flipped so that higher pressure now remains over the Atlantic basin. This is likely to revert to low pressure during the second half of September, and that's when tropical activity will begin to increase.

The lack of a new named storm in September is notable, but it's highly unlikely we're going to make it through the entire month without another named storm. I would suspect that the Atlantic spins up more than one. Back in 1992, Bonnie, the second named storm of that season, formed on Sept. 18.

Depending on when our next named storm occurs, we could end up surpassing that mark. The National Hurricane Center is monitoring a tropical wave, Invest 92L, in the Central Atlantic that's producing a cluster of showers and thunderstorms that will likely gradually develop mid- to late week into a tropical depression. The NHC on Monday gave the disturbance a 90 percent chance of formation.

How does climate change factor into all of this? Well, climate change is a big factor, but weekly and monthly conditions can play a bigger role in the short run. Parts of the Atlantic, including the Gulf of Mexico, are near or at record warmth for this time of the year due to global warming. Warm seawater is the fuel for tropical systems. But it's not the only necessary ingredient for hurricanes to form. Actually, some of the other factors I mentioned are obviously suppressing activity in spite of the warmth in the water.

Another player in the tropical forecast game is the El Niño-Southern Oscillation (ENSO) off the coast of South America, which is currently in a neutral phase, helping keep the waters quiet.

As recently as last year, the Atlantic saw a 27-day lull with no new named storms from Aug. 13 to Sept. 8. The bottom line is that odds favor an increase in activity over the next couple of weeks, even though we're now on the back side of hurricane season. A late-season storm could still very well bring tremendous impacts.

Atlantic tropical storms may have stalled, but all eyes are on a fresh threat, Invest 92L - The Boston Globe