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Autumn storm to sweep across Finland on Wednesday

The brunt of the wind and rain is expected to hit southern areas on Thursday.

Matalapaine tuo syysmyrskyn Suomeen keskiviikkona ja torstaina
  • Yle News

An unusually strong autumn storm is set to arrive in Finland on Wednesday, according to the Finnish Meteorological Institute (FMI).

The storm is expected to cause possible power outages caused by trees taken down by the wind as well as very rough conditions at sea.

In its forecast, the FMI said the major storm system will reach Finland's west coast on Wednesday afternoon and as it moves eastward would intensify through the night.

Heavy rain and strong winds are expected to spread over central and southern areas and continue into Thursday.

Storm-level winds will likely be reached in the Gulf of Bothnia as early as Wednesday afternoon. Along the southwest and west coast, gusts are expected to reach 25 m/s.

As the storm progresses, wind speeds will intensify in northern areas as well, reaching eastern areas of the country on Thursday afternoon, where gusts up to 20 m/s are anticipated, according to the forecast agency.

Clouds and rain are expected to arrive in central and northern areas as early as Wednesday morning.

Story continues after weather graphic

Kuva näyttää sademäärän kehittymisen.
Rainfall projections in Finland for Wednesday (KE), Thursday (TO) and Friday (PE). Image: Anne Borgström / Yle

Local flooding likely

In the south, rainfall levels will still be relatively low on Wednesday, but the precipitation is expected to increase on Thursday.

According to FMI's on-call meteorologist, Iiris Viljamaa, up to 70 mm of rain is expected across areas of central Ostrobothnia, Central Finland and North Savo, which will likely cause local flooding in some areas.

"There will certainly be water left on the flat fields and ditches will flood," she said.

Meanwhile temperatures in the south could still be relatively mild, and as high as 18 degrees on Wednesday, but elsewhere temperatures will over around 10 degrees in rainy areas.

But on Thursday temperatures of 6-10 degrees are expected across the country, including in southern areas.

Such a powerful storm is unusual this early in the autumn and generally not seen until November or December according to Viljamaa.

"It's a very strong storm for this time of year," she said.

Significant damage expected

The FMI said the early autumn storm would likely cause significant damage, as northerly winds can be particularly damaging to trees.

In recent times, northern winds have become increasingly rare, making the trees which are susceptible to such gusts more likely to be taken down.

Viljamaa also said that gusts on land will likely be powerful enough to peel off roof tiles and chimney caps, noting that tarpaulins at places like construction sites should be properly secured.

At sea, there are warnings issued concerning four-metre sea swells, but Viljamaa said they could be as high as six or seven metres, at least in the Bothnian Sea.