Switzerland: Adverse weather forecast across much of the country through at least Sept. 27

Severe weather is forecast across much of Switzerland through at least Sept. 27. Heavy rainfall accompanied by strong winds will begin in western regions early Sept. 26 and spread through much of the country throughout the day. Rainfall totals of 4-8 cm (1.6-3.1 inches) are expected in western and northern regions. Heavy rainfall may trigger flooding in low-lying areas, and strong winds may cause property damage and power outages.

As of Sept. 25, MeteoSwiss has issued orange heavy rainfall warnings (the middle level on a five-tier scale) across much of western and parts of northern Switzerland. Yellow heavy rainfall warnings are in place for parts of northern and west-central Switzerland and orange advanced notice of heavy rainfall warnings have been issued for southeastern regions. Yellow strong wind warnings have also been issued for parts of western Switzerland. Officials could update and possibly extend the coverage of weather alerts over the coming hours and days.

Sustained heavy rainfall could trigger 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 cannot be discounted in hilly or mountainous areas, especially where the soil has become saturated by heavy rainfall. Disruptions to electricity and telecommunications services are possible where significant winds, flooding, or landslides impact utility networks.

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 regional airports. 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.