Kainuu’s forested hills gather snowdrifts

In Hyrynsalmi, the snow-depth is already over 110 cm, and there is more to come

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By Heli Saavalainen
     
      Trees covered by icy snow rise like enormous columns out of powdery drifts on the Paljakka fell in Hyrynsalmi in Eastern Finland.
      The snow lying on the ground is downy-soft, and even when wearing snowshoes one tends to sink into the white up to the thighs.
      Hyrynsalmi resident Tuomo Romppainen, 47, is trudging through virgin snowdrifts, thrusting a measuring-stick into the snow.
      ”More than a metre. Since January, some 30 to 40 centimetres of new snow has fallen", he reports.
      On top of the fell, at 384 metres above sea level, the stick sinks down to 110 centimetres. ”The snow cover is always the thickest up here”, notes Romppainen.
     
Romppainen knows what he is talking about. Once a month he comes to the top of Kainuu - Hyrynsalmi’s Paljakka is only three metres lower than the highest hill, Iso Tuomivaara - in order to measure the thickness of the snow cover. He has been doing this for 13 winters now.
      ”In 1998, on April 14th, the snow cover was 162 centimetres thick”, he recalls.
      Romppainen forwards the information on the depth and weight of snow to the Finnish Environment Institute (SYKE), where the water equivalent of snow or snow load is measured.
     
The measuring sites are on the snowiest wilds of Finland. While the quantities of snow are the biggest in the Käsivarsi Wilderness Area [the very far northwestern corner of Lapland] and in Eastern Lapland, Kainuu’s forested hills have gathered more snow than anywhere else in the country.
      Käsivarsi, by the way, is the Finnish word for an arm, referring to the raised arm of the Maiden of Finland.
      Year after year, the Paljakka fell (actually it is not strictly speaking a fell, as the top does not protrude above the tree-line) is shown as a dot on the maps indicating the thickness of snow cover.
      Apart from Lapland, the thickest snowdrifts are consistently found on Hyrynsalmi’s Paljakka. Whyever is it that the focus of Finland's snow is on Paljakka?
      ”The reason for this lays in the layout of the hills. Snow tends to gather particularly on Lietekylä’s Lumivaara hill and on Hyrynsalmi’s Paljakka”, Romppainen says.
     
The phenomenon is called an orographic effect which means that precipitation is generated by a forced upward movement of air upon encountering any part of a region’s elevated terrain, such as hills. If enough water vapour condenses into cloud droplets, these droplets may become large enough to fall to the ground as precipitation.
      ”The differences in terrain levels are likely to gather snow on certain places even in a relatively flat country like Finland”, says hydrologist Esko Kuusisto from SYKE.
      "The snow line of Paljakka in Hyrynsalmi runs mainly at a height of more than 350 metres. The terrain gains height rapidly particularly in the direction of the south and west, while some ten kilometres away the elevation is generally below 200 metres, which causes an orographic effect”, Kuusisto reports.
      ”In winter the clouds are generally low, which is why the orographic effect is then strong”, he adds.
      Even the air temperature declines when the elevation increases, even in tens of metres. In winter precipitation falls down in the form of snow, and the thawing process is slow.
     
In addition, a lot of icy snow is generated, and the hard snow and frost have coated the spruces, turning them into giant works of art.
      Icy snow could weigh as much as three to four tons on a single tree. However, surprisingly few trees have lost their tops.
      ”The spruce is a tough old bird”, Romppainen notes.
      The man walks slowly, filling his instrument with snow and weighing the whole lot. The device indicates that the water equivalent of icy snow is 96 kilogrammes per square metre.
      Actually, the mere depth of snow underfoot does not tell the real amount of snow, as the compact and wet snow weighs many times more than does light frosty powder snow. The snowload per area unit or the water equivalent of snow provides an answer to how much the snow really weighs.
      SYKE has 150 snow lines for measurement up and down the length of Finland, and they are regularly observed by dozens of individuals similar to Tuomo Romppainen, often trudging through deep snowdrifts.
      On the Kainuu hill-tops it takes several hours to make such an observation trip, as on the route there are 80 measuring sites for the thickness of snow cover, and another eight for the density of snow. Circling in deep forest, the route is many kilometres long.
     
The snowdrifts continue to grow in Hyrynsalmi. At first the snow flutters down as light feathery flakes, gradually gathering momentum to thow down a real blizzard.
      There will be no shortage of materials for those coming skiing here this week, as Finland marks the first of its three February "skiing holiday" vacation weeks.
     
     
Helsingin Sanomat / First published in print 16.2.2009


Links:
  FMI: Snow statistics
  Orographic Precipitation (Wikipedia)
  Finnish Environment Institute (SYKE)
  National Land Survey of Finland
  Finnish Meteorological Institute (FMI)

HELI SAAVALAINEN / Helsingin Sanomat
heli.saavalainen@hs.fi