Record rains take a brief break, but damage already done

Roads inundated, and the flooding River Vantaa is feeding nutrients into the sea

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We've been going on and on about the mild and rainy conditions for weeks, and it has not been all exaggeration.
      The latest burst of wet and windy weather down south looks to have been the last straw: since Saturday, it kept on raining incessantly in the Greater Helsinki area for more than two days, and the rivers started to overflow their banks with a vengeance, giving rise to scenes that are more familiar in the spring snow-melt and in the low-lying areas of Ostrobothnia on the West Coast.
      On Monday afternoon the rain abated - briefly.
     
The amount of precipitation recorded during the two or three days at the measuring station at Helsinki-Vantaa International Airport was almost as high as is usually received in the entire month of December on average.
      ”This December has been exceptionally rainy and mild. Rainfall records are being broken in the capital region. December has also been a few degrees warmer than average, as Finland has received temperate western currents. This is likely to be among the five warmest Decembers in the past 50 years”, says meteorologist Niina Niinimäki.
     
The current month has been certainly been the wettest December in the capital region in more than 50 years. According to the Finnish Meteorological Institute, the last time when the measuring station at Helsinki-Vantaa recorded a higher amount of precipitation than the present figures was in 1954.
      That record was in serious jeopardy, too: in the course of the first weeks of December, the amount of rain that came down was 127.5 millimetres, which is only one millimetre lower than the record set in 1954.
      At Helsinki’s Kaisaniemi measuring station, the amount of precipitation recorded has been larger than this last in 1981. In the current December, Kaisaniemi’s total rainfall so far has already climbed to 94 millimetres.
     
The heavy downpours have also been disrupting road traffic.
      The largest amounts of water have been seen on the Helsinki-Turku motorway.
      Around midnight, the Traffic Control Centre reported that one Turku-bound lane between Ring Road III and the Tuomarila intersection will have to be kept closed for the time being.
      The centre was not able to estimate whether the lane could be open on Tuesday morning.
     
A total of about 20 to 30 rescue workers were working along the Espoo River all night. They were fully prepared to see the water level rise to reach the lower floors of buildings.
      The water has already risen close to the Espoo Cathedral and the buildings in the Kirkkojärvi residential area.
      Even on Vihdintie (Road 120), on the low-lying section of the road in Vantaa’s suburb of Askisto, the water flowing from the fields is covering part of the carriageway.
      In Helsinki, the water has formed a giant puddle at least in the popular Sibelius Park. In Espoo, a small lake has emerged near the new buildings going up in the Suurpelto residential area next to Ring Road II.
     
When the River Vantaa feeds rain waters into the sea, simultaneously a large amount of nutrients from the fields ends up in the sea as well.
      Assuming that the flow will continue like this, half of the average annual load of the River Vantaa may flow into the sea in a fortnight, says special researcher Seppo Knuuttila from the Finnish Environment Institute (SYKE).
      ”In about a week, approximately the same amount of phosphorus ends up in the Gulf of Finland as goes with Helsinki’s waste water annually - if the flow remains like this”, Knuuttila notes.
     
Knuuttila regards it as very likely that the long-term average values of nutrient loads will be exceeded this year in Southern Finland.
      On Monday afternoon, the abundant rainfall led to a situation in which the Viikinmäki wastewater treatment plant started to lead cleaned waste water to Vanhankaupunginlahti Bay.
     
The forecast for the next few days is mild and unstable weather, but the rains will abate slightly, reported on-duty-meteorologist Antti Ylhä-Ollila from the Finnish Meteorological Institute.
      Early this week, the weather is expected to cool down slightly, but after a low on Wednesday and Thursday of a degree or two below freezing point, on Friday the temperature is predicted to rise above zero again.
      Moreover, new rainfalls are expected in the capital region on Friday.
      ”There is no prospect of a white Christmas in the Greater Helsinki area”, estimates Ylhä-Ollila.
      And not much prospect of seeing the sun, either.


Previously in HS International Edition:
  Rain brings flooding to lakes and rivers in south of Finland (15.12.2011)
  Very bad conditions on the roads spreading across the country (9.12.2011)
  Helsinki hit by unusually heavy deluge; streets and cellars flooded on Monday evening (23.8.2011)

Links:
  Finnish Meteorological Institute: Helsinki local weather
  CIty of Helsinki UrbanTraffic Control Centre
  Road weather cameras in Southern Finland (Finnish Transport Agency)

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