Unusually mild Atlantic hurricane season likely to ramp up

Between the lines: The causes of the pause come down to a few big factors.

• The unusually stable atmosphere over the tropical Atlantic, which discourages the air from rising, cooling and condensing into clouds and forming organized storms.
• In addition, the region where the trade winds meet, known as the Intertropical Convergence Zone, has been displaced well to the north of its typical position across Africa.
• This has caused seedlings for tropical storms and hurricanes to emerge off the west coast of Africa near northern Mauritania and Western Sahara rather than the more typical location of Senegal. These clusters of thunderstorms quickly cross over cold waters and dissipate.
• The unusually active African monsoon has also bolstered easterly winds at mid-to-upper levels of the atmosphere across large parts of the tropical Atlantic. This causes wind shear that tears incipient storms to pieces.

Yes, but: The quiet in the Atlantic Ocean basin, which in an active season would be giving rise to multiple storms and hurricanes at this time of year, appears to be on the verge of ending.

• The National Hurricane Center is watching for the possibility of storm development southeast of the Lesser Antilles during the next week, and computer models project other possible systems dotting the Atlantic in the next week to week and a half.
• Phil Klotzbach, a meteorologist at Colorado State University, said the convergence zone and related African Monsoon are likely to slide back south through early September, and other storm suppressants may lose their efficacy.
• The areas to look at for storms to form will include the central and eastern Atlantic, he said.
• In addition, as the season progresses, storms are more likely to form in the Gulf of Mexico and the Caribbean. Ocean temperatures there are well above average.

By the numbers: This season is running above average in most measures of storm activity, having had three hurricanes, including one major hurricane already.

• This season is also ahead of the long-term average when it comes to a key measure of the strength and duration of Atlantic storms.
• However, Klotzbach says if the quiet period were to extend longer than expected, 2024 could fall below average for a time.

The intrigue: According to top hurricane experts, a variety of difficult-to-predict factors combined to keep a lid on tropical storm and hurricane activity during much of mid-to-late August.

• Michael Lowry, a hurricane specialist and storm surge expert at WPLG TV in Miami, says if two weeks pass since the demise of Hurricane Ernesto on Aug. 20 without a new tropical or subtropical storm system to track in the Atlantic, it would be the first time that has happened during this time of year since 1956.

• Klotzbach says there have only been four times since the start of the satellite era in 1966 without any named storms between Aug. 21 and Sept. 2, most recently in 1997. "All four of those were extremely quiet seasons," he told Axios via email.
• This season, however, has not been quiet, with Hurricane Beryl shattering records for the earliest Category 5 storm yet observed.

Zoom in: Tropical cyclones are nature's most powerful and expensive storms, and climate change is making them more intense, wetter and slower moving.

• The Atlantic respite is occurring despite near-record warm ocean temperatures, which are also tied to climate change.
• This demonstrates that ocean temperature anomalies are not sufficient for forming powerful hurricanes (but they do help if other conditions are right).

Our thought bubble: The absence of storms during a time of year that is often teeming with them shows some of the challenges in making and communicating seasonal forecasts.

• A projection for an above-average year does not mean there would not be periods of relative quiet, for example.

What's next: If the most recent computer model projections are accurate, the storm respite may look more like a mirage within two weeks.