Switzerland: Adverse weather forecast across southwestern, west-central, and western regions through at least Oct. 2

Heavy rainfall is forecast across parts of southwestern, west-central, and western Switzerland through at least Oct. 2. A weather system is expected to bring rainfall totals of 5-9 cm (2-3.5 inches) between Lower Valais and the western Bernese Oberland and 3-5 cm (1.2-2 inches) across surrounding areas from the afternoon Oct. 1 to the morning Oct. 2. Heavy rainfall may trigger flooding in low-lying areas and landslides on unstable slopes.

As of Sept. 30, MeteoSwiss has issued orange heavy rainfall warnings (the middle level on a five-tier scale) across parts of southwestern Bern, southern Fribourg, western Valais, and southeastern Vaud cantons. Yellow heavy rainfall warnings are in place across the rest of the affected area. 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.