Weather The Liisa storm that raged on Thursday was not exceptional in 2020 – there have been an exceptional number of storm days and named storms in Finland this year

This year, more storm days have been counted than ever since the Finnish Meteorological Institute began counting them in 2016 using current statistical methods.

Meteorological since 2006, the facility has been collecting statistics on how many stormy days a year can hold. By 2020, there had been 40 storm days by Saturday – one more than the entire previous record year of 2007.

On average, there have been 27 storm days per year during the statistical period.

“After all, this has been a stormy year compared to other years in that statistic,” says the meteorologist Ville Siiskonen From the Finnish Meteorological Institute.

According to the Finnish Meteorological Institute, a storm day is a day on which at least one sea weather observation station has measured a mean wind speed of at least 21 meters per second for 10 minutes.

Unusually the storms were especially early in the year. There were ten storm days in February, while the average for February during the statistical period has been 2.7.

“Until April, there were clearly more stormy days than typical. The variation between the years in Finland is great, ”says Siiskonen.

The year 2014 was particularly calm in terms of storm days, when only 16 storm days were counted. It was almost as calm in 2006 and 2009, when there were 17 stormy days.

However, Siiskonen points out that counting the days of storms does not have a very long history in Finland yet. The Finnish Meteorological Institute has only calculated them using current statistical methods since 2006.

“Comprehensive wind measurements are quite young compared to what has been measured at observation stations, for example, for temperatures or snow depths. There are statistics for decades, ”says Siiskonen.

The discrepancies in wind measurement are due, for example, to the fact that in the past winds were not measured as often as they are today.

Storm days in addition, an exceptional number of storms have been named this year. Significant storms and severe winds get the name.

“This year stands out for being nominated [myrskyjä ennen Liisa-myrskyä] there have already been three songs, ”says Siiskonen.

Thursday’s Liisa storm had not yet had time to be included in that list, but Siiskonen believes that it will be the fourth major storm this year.

“I guess that Liisa storm goes into the same category,” says Siiskonen.

A tree that fell in the Liisa storm was walked over in Helsinki on 19 November 2020.­

According to the Finnish Meteorological Institute, names are given to major storms and severe weather. Is the significance of certain conditions, such as the fact that it causes more than 1 000 rescue missions, takes power for more than 100 000 households, or cause damage to trees for at least half a million cubic meters of the area.

This Aila, who was furious from the storms of the year in mid-September, has been the strongest, at least so far. Other storms named this year are Wind in February and Päivö in summer. All of those storms were caused by storm low pressure.

“This year has been significant especially in terms of storm pressure,” says Siiskonen.

However, harder storms were seen almost a decade ago.

“2011 was the Tapani storm and the Hannu storm for two consecutive days,” says Siiskonen. Both storms are among the strongest in Finland, at least in recent history.

There are several years in the history of measuring significant storms and severe weather, when no storm or severe weather in Finland has been considered so significant that they have been named. The most recent such peaceful years were 2018 and 2012.

The tradition of naming storms extends far in Finland as well. In the statistics of the Finnish Meteorological Institute, the first named violent weather is Maire, which raged in August 1961.

Lisa’s storm in the wake of the winds have already calmed down.

However, it is possible that new entries will be made in this year’s statistics. An average of 6.6 storms have been measured in December.

An outsider on the shores of Kaivopuisto, Helsinki, November 19, 2020 during the Liisa storm.­


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