Southern Norway’s flirt with sunny summer weather during the past week came to an abrupt, if forecast, halt on Monday. Heavy rainfall didn’t only dampen summer holiday spirits but also raised the threat of flooding to some of their highest levels yet.
The warm weather that finally settled over most of southern Norway last week also increased the rate of snowmelt in the mountains. By Sunday, the state Meteorological Institute was sending out warnings for the inner portions of the counties of Hordaland and Sogn og Fjordane, and all of Møre og Romsdal.
‘Lots of precipitation’
Forecasters warned of mye nedbør (lots of precipitation), with heavy rain also in Aust-Agder and Telemark counties and southeastern Norway. In the Oslo area, the rain was so heavy that it woke up some residents around 4am. The warm, dry days of the weekend were gone in a flash.
The rain and warm temperatures were also causing major concern at the state waterways agency NVE, which posted flood warnings in the “orange” category and heading into red alert levels on Sunday afternoon. That’s because the rain, combined with snowmelt, was already turning waterfalls, rivers and creeks into torrents, with the water level of lakes around Voss, for example, rising a full meter in the course of the weekend.
“Some of our waterways can rise to five-year flood levels,” Brigt Samdal, regional chief for NVE, told Norwegian Broadcasting (NRK) on Monday. “It’s difficult to say, but we’re going to see roaring water in most waterways today and tomorrow.”
Officials at NVE have been worrying about effects of the annual snowmelt since early last month, when the record-cold spring that extended well into June dumped even more snow in the mountains and prevented all the mounds already there from melting at a steady rate. There are also record amounts of snow at high elevations that may last until next winter, but lots of it is now melting at a faster rate than NVE regulators like.
That’s why they’ve now posted flood warnings in Aust-Agder, Buskerud, Hordaland, Møre og Romsdal, Oppland, Rogaland, Sogn og Fjordane og Telemark. Around 50mm of rain were expected in Hordaland og Sogn og Fjordane in the course of Monday, with the danger that rivers can start raging out of control.
“We have some demanding days ahead of us,” Samdal told NRK.