Norway, Sweden: Authorities maintaining flood warnings across parts of the region as of Aug. 22 /update 4

Event

Authorities are maintaining flood warnings across parts of southeastern Norway and southeastern Sweden as of Aug. 22. Widespread flooding occurred in the region as Storm Hans passed through the area Aug. 7-10; although floodwaters have receded in most areas, river levels remain high and further rainfall in the intervening period has exacerbated the situation.

As of Aug. 22, the Norwegian Meteorological Institute is maintaining red flood warnings (the highest level on a three tier-scale) for parts of southern Innlandet and central Viken counties. Orange flood warnings are in place for parts of south-central Innlandet and northeastern Viken, as well as yellow flood warnings for parts of central and eastern Vikken. Yellow landslide warnings are also in place across the affected areas. The Swedish Meteorological Institute issued red flood warnings for areas along the Delangersan River through at least Aug. 25, as well as orange and yellow flood warnings across several other waterbodies in southeastern Sweden. Officials could update and extend the coverage of weather alerts over the coming days. Further heavy downpours could trigger additional flooding, especially in areas where river levels are already high and the ground is saturated from previous rainfall.

Around 4,000 people were evacuated across parts of southern Norway during the passing of Hans; most residents have now returned home. A railway bridge in Ringebu, Innlandet County, collapsed into the Lagen River Aug. 14, and the Braskereidfoss hydro-electric power plant on the Glama River in Innlandet County partially collapsed Aug. 9. All major roads were closed, and many rail services were disrupted in the affected region following the passing of the storm. In Sweden, a train derailed between Iggesund and Hudiksvall in eastern Sweden Aug. 7 during the storm, and much of the port of Gothenburg was flooded. Severe flooding also occurred in Are Municipality in Jamtland County, and several roads and rail networks in affected areas were blocked by flooding and landslides.

Hazardous Conditions
Further sustained heavy rainfall could trigger additional flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed stormwater drainage systems. Sites located downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where heavy rainfall has saturated the soil.

Authorities could issue mandatory evacuation orders for flood-prone communities over the coming days. Disruptions to electricity and telecommunications services are possible where significant flooding or landslides impact utility networks.

Transport
Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters. Severe weather could also trigger flight delays and cancellations at airports in the region. Flooding could block regional rail lines; freight and passenger train delays and cancellations are likely in areas that see heavy rainfall and potential track inundation.

Localized business disruptions may occur in low-lying areas; some businesses might not operate at full capacity because of flood damage to facilities, possible evacuations, and some employees' inability to reach work sites.

Advice

Monitor local media for weather updates and related advisories. Confirm all transport reservations and business appointments before travel. Make allowances for localized travel delays and potential supply chain disruptions where flooding has been forecast. Do not drive on flooded roads. Charge battery-powered devices in the case of prolonged electricity outages.

Resources

MeteoAlarm
Norwegian Meteorological Institute
Swedish Meteorological and Hydrological Institute
Norwegian Public Roads Administration
Swedish Civil Contingencies Crisis Information