Far-Reaching Consequences: Tropical Hurricanes to Affect Weather in Scandinavia

hile large masses of hot sea water above 25 degrees are the foremost prerequisite for a hurricane like Irma, which recently hit the US East Coast with torrential rains, its consequences may reach as far as northern Europe, albeit in a less destructive way.

"A weakened hurricane can interact with a low-pressure zone via the Westerlies on its way here," meteorologist Mattias Lind at the Swedish Meteorological and Hydrological Institute (SMHI) told the Swedish daily Svenska Dagbladet.

The newspaper cited a similar instance of a hurricane reaching the northern shores that happened in July 23, 1985, when the aftershocks of a tropical storm triggered a fierce gale off the coast of Småland County in southern Sweden. Many boats capsized in what was later dubbed the Öland Storm (after Öland County), flooding the ether with signals of distress. The Baltic aftershocks reportedly cost two people their lives.

Having originated in North America, the hurricane crossed the Atlantic through an unlucky combination of winds and low pressure, releasing energy by condensing vapor into water droplets and subsequently developing into an intense storm over the Baltic Sea, with wind speeds of about 27 meters per second. According to eyewitnesses, the wind became stormy in almost no time. The Öland Storm became a starting point for a heated discussion on forecasting methods and observation techniques.

An even more powerful example of the same phenomenon of a tropical cyclone reaching Europe occurred in October 1987, when dying hurricane Floyd triggered a low pressure area that developed into the worst storm in London since 1703. At least 22 people died in gales reaching as high as 200 kilometers per hour.

"In trade jargon, we talk about tropical low pressure turning into extratropical low pressure. Interaction via the Westerlies may initiate another low pressure zone. It's all about timing," Mattias Lind said.

Hurricanes themselves tend to die down when they reach the Westerlies, but their energy is transferred by powerful windbreaks at a height of 7 to 13 kilometers, which are called "jet streams." The energy can subsequently be transformed into new storms which are not hurricanes as such, yet are most difficult to predict.

"It's true we're generally not affected by tropical hurricanes, but the whole world hangs together," Mattias Lind noted.

According to research director Gunnar Myhre from the climate research center Cicero in Oslo, there is a consensus in the scientific community that while the tropical hurricanes will not occur more often, they are predicted to become more powerful, the Norwegian newspaper Klassekampen reported.

Meanwhile, natural calamities expert at Länsförsäkringar insurance company Pär Holmgren called the recent spate of hurricanes "a huge warning clock," pointing out that many areas affected by hurricanes Harvey and Irma were completely uninsured. Holmgren also added that climate change may in the future make entire regions impossible to insure, not only in the US, but also in Sweden, Svenska Dagbladet reported.

Within the past several weeks, the US has been hit by two deadly hurricanes, Harvey and Irma, which have destroyed billions of dollars' worth of property. Incidentally, this marked the first time in 166 years of weather records when two Atlantic Category 4 hurricanes made landfall in the US during the same year.