Switzerland: Adverse weather forecast across much of the country through at least early July 13

Severe weather is forecast across much of Switzerland through at least early July 13. A low-pressure system is expected to bring thunderstorms and heavy rainfall across parts of the country over the coming days, with the worst of the severe weather likely on the southern side of the Alps. Strong wind gusts, lightning, and hail may accompany storms. Heavy rainfall may trigger flooding in low-lying areas, and strong winds may cause property damage and power outages.

As of July 11, MeteoSwiss has issued red warnings (the second highest level on a five-tier scale) for thunderstorms with a low chance of occurrence across Ticino and parts of southern and southwestern Grisons cantons. Orange warnings for thunderstorms with a low chance of occurrence are in place across much of the rest of Switzerland, with the exception of some southern and southeastern regions. Orange heavy rainfall warnings have been issued for parts of western Grisons and southern Uri cantons. Yellow heavy rainfall warnings are in place across much of the rest of central and eastern 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.