The start of the Atlantic hurricane season was lackluster – but it’s still early


Ahead of this Atlantic hurricane season, there were many signs pointing to a stormy summer and fall. Forecasters said major weather patterns governing the oceans and atmosphere would come together to boost activity; experts from the National Oceanic and Atmospheric Administration and Colorado State University predicted above-to-well-above-average activity. Not to mention that climate change has primed the oceans for the development of strong tropical systems.

The one thing that seems to be missing from a busy Atlantic hurricane season? Hurricanes.

Only three tropical storms have formed so far this year in the Atlantic Basin. While the third named storm doesn’t normally form until August 3 — meaning this year is ahead of average by this metric — the storm count doesn’t tell the story.

All three systems were “shorties,” brief, low-intensity tropical storms with limited impacts. As a result, the cumulative cyclone energy (ACE), a measure of the cumulative power of all Atlantic tropical storms, is about one-third of normal for the date.

The seasonal deficit will only continue to grow unless activity begins to pick up dramatically in August and September – the historic peak of hurricane season – when stronger, longer-tracked systems develop. usually. But there are no immediate signs of this ramp-up starting.

Scientists predict seventh consecutive above-average hurricane season

Neither US nor European model ensemble prediction systems – supercomputer simulations, each of more than a dozen slightly different atmospheric scenarios – show much signal for tropical activity until the end of the first August week. Similarly, the National Hurricane Center did not highlight any five-day predicted development regions.

For now, there’s no one to blame for the lackluster development.

Episodes of strong low-latitude winds and widespread descending air have at times impeded development, while persistent outbreaks of dry, dusty air from the Sahara Desert have helped stifle blooming thunderstorms that can sometimes turn any surviving tropical waves into organized storms.

As a result, the systems that have developed are either tropical depressions that do not strengthen at all, or depressions that develop so close to land that there is not enough time for them to strengthen. . So while the systems may have a marginal impact — Alex, the first named storm of the season, brought torrential rains to southern Florida in early June, for example — they don’t contribute much to the seasonal ACE.

But this kind of lower-than-expected activity isn’t uncommon this early in hurricane season, even in years that get quite active. And there are still signs that peak season could see a number of hurricanes.

For better predictions, hurricane hunters probe deep into storms

In a press release issued in early June, leading scientists at Colorado State University continued to forecast a season of well-above-average activity. Despite a lackluster first two summer months, the release continued to cite many seasonal factors that generally lead to strong tropical development.

First, there is El Niño/Southern Oscillation, often abbreviated as ENSO. Linked to the sloshing of warm and cold waters around the Pacific, the oscillation has influences on long-term atmospheric conditions around the world. Years with La Niña — the phase of oscillation currently in effect, according to the National Oceanic and Atmospheric Administration — tend to see more hurricane activity in the Atlantic, with conditions unusually favorable for the development and strengthening of tropical systems.

The presence of La Niña, combined with ocean temperatures in the Atlantic that are currently warmer than average – a testament to both a warming world and favorable winds – gives forecasters confidence in a more active hurricane season.

History also tells us to avoid betting too much on early season activity.

It is the first year since 2017 that a hurricane has not developed in the Atlantic as of August 1. That year, an unbroken streak of nine consecutive hurricanes formed from late August to mid-October, including the devastating Harvey, Irma, and Maria.

In 2015, there were also no hurricanes as of August 1; it was the most recent year to end up with below-average tropical Atlantic activity.

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