A waterspout is a whirling column of air and mist that forms over a large body of water. They can form in conditions ranging from calm to extreme stormy weather. But, while fair-weather waterspouts are generally less dangerous, tornadic waterspouts can be highly destructive. These have the potential to produce strong wind, disrupt seas and cause significant damage to vessels in their path.

So, could such a phenomenon have sunk the Bayesian?

The Bayesian sank in the early morning of August 19, 2024, off the coast of Sicily. The ship belonged to British businessman Mike Lynch, who reportedly was celebrating his acquittal of fraud charges. It sank quickly whilst at anchor during a storm. And, according to witnesses, the yacht was struck by a “black swan” waterspout.

What is a Waterspout?

Waterspouts are essentially tornadoes that occur over a body of water. Like their land-based counterparts, they consist of a rapidly rotating column of air, but unlike tornadoes, they form over water and are often less destructive. Despite their name, waterspouts do not suck up water from the ocean or lake surface. Instead, the funnel you see is actually made of water droplets formed by condensation, much like the condensation in a cloud.

Waterspouts can occur almost anywhere there is a large body of water and the right atmospheric conditions. They are most common in tropical and subtropical regions, particularly in the waters off Florida and the Bahamas, where warm water temperatures and humid air create ideal conditions. However, they can also appear in cooler climates, such as over the Great Lakes or even in the Baltic Sea.

There are two main types: fair-weather waterspouts and tornadic waterspouts. And though they may look similar, their formation processes and potential impacts differ significantly.

Fair-weather waterspouts typically form along the flat base of cumulus clouds, often in relatively calm conditions. They are generally less dangerous, primarily affecting small boats or creating dramatic displays for onlookers along the coast. These waterspouts tend to be weaker and shorter-lived, posing less of a threat compared to their more violent counterparts.

Tornadic waterspouts, on the other hand, are far more dangerous and share many characteristics with land-based tornadoes. These waterspouts form during severe thunderstorms and can either develop over water or transition from land to sea. According to the National Ocean Service, tornadic waterspouts are often accompanied by severe weather conditions. They occur with high winds, heavy seas, large hail, and frequent lightning — conditions that can be catastrophic for any vessel caught in their path.

A black swan event?

The sinking of the Bayesian yacht has been described by some as a “black swan” event — a rare and unpredictable occurrence with catastrophic consequences. The term was popularized by Nassim Nicholas Taleb in his 2007 book, referring to rare but consequential events that are beyond normal expectations, have a major impact, and are often rationalized after the fact with the benefit of hindsight.

Tornado formation can be detected by radars — although information regarding strength isn’t known until the tornado takes shape. However, waterspouts last a shorter time and may evade radar detection. This event also happened at night, when perhaps no one was watching the radar anyway.

Luca Mercalli, a leading Italian climatologist says the crew should have paid attention to weather alerts.

“I don’t know if there was anyone on board consulting the radar,” he told The Telegraph. “Let’s say that if I had been on board, at the first sign of a thunderstorm I would have woken up all the occupants and been ready and alert with life jackets on until the storm was over.”

Matthew Schanck, chairman of the Maritime Search and Rescue Council, explained to The Times that there was no severe forecast — it was just unexpected.

“I’ve reviewed the forecasts. There was nothing other than thunder. There was nothing that jumped out to me that made it a dangerous decision to anchor there,” he said.

“That water carries significant weight,” Schanck added. “And if the waterspout ends up dumping a load of that water on board the vessel, that’s going to cause significant damage.”

This sudden accumulation of water, combined with the intense rotational force of the waterspout, could have easily overwhelmed the yacht, causing it to capsize before the crew and passengers had time to react

How waterspouts form and what happened that day

Tornadic waterspouts form in a manner similar to tornadoes. They typically develop when a thunderstorm’s updraft — rising warm, moist air — interacts with a strong downdraft of cooler air descending from the storm. This interaction can create a rotating column of air. And, if it extends downward to contact with the water’s surface, it becomes a waterspout.

The conditions to form a waterspout were there. Still, without hindsight, it’s not clear how likely a dangerous waterspout would have seemed.

“There was a big thunderstorm just to the north of Sicily, a lot of lightning activity, lot of heavy rain, very strong signature of what we call ‘cold cloud tops’ on the satellite pictures,” explained Dr Pete Inness, a meteorology lecturer at the University of Reading. “All of those things would add up to a thunderstorm that could easily spawn a waterspout”.

The fact that the incident occurred at night added another layer of danger. With limited visibility, it would have been even more challenging for the crew to spot the approaching waterspout in time.

Are waterspouts dangerous or was this a freak event?

In Europe, around 160 waterspouts are reported every year. They may increase in frequency and intensity with climate change, although it’s not clear how much of an impact the shifting climate will have.

“Rising global temperatures due to climate change means warmer air, which allows it to hold more moisture, roughly 7% more moisture per 1°C of warming. This boosts the chance of thunderstorms, leading to more violent storms and more lightning strikes. And the intense downpours will lead to localised flash flooding,” notes the British Royal Meteorological Society. The same phenomena may also make waterspouts more intense.

The yacht appears to be “practically intact” on the bottom of the sea, with no gashes or signs of impact. It seems the vessel sunk due to the overwhelming force of the waterspout.

Ultimately, the sinking of the Bayesian underscores the unpredictable and often dangerous nature of waterspouts, particularly in regions prone to severe weather. While technology has made significant advances in weather forecasting, there are still limitations when it comes to predicting rare and extreme events like tornadic waterspouts.

Sailors should also ensure that they have the necessary equipment on board to detect and respond to weather threats. This includes radar systems capable of identifying severe storms, as well as safety equipment such as life jackets and emergency beacons.