Avalanches driven by heavy snowfall struck the European Alps over the weekend, causing a train derailment in Switzerland and multiple skier deaths. On Monday, Swiss police reported that an avalanche derailed a train near Goppenstein, injuring five people. Around Mont Blanc, roads and villages were closed or evacuated as avalanche risks remained extremely high. The western Alps have faced severe avalanche warnings all week, reaching category 5—the highest level. Recently, several deadly avalanches occurred involving skiers in France and Italy. On Friday, three skiers, including two Britons, died in Val d’Isère, France. The ski instructor accompanying them survived and tested negative for drugs and alcohol. Another Briton suffered minor injuries. On Sunday, two skiers died in an avalanche on the Italian side of Mont Blanc in the Couloir Vesses, a popular off-piste route near Courmayeur. These tragedies add to 13 off-piste skier, climber, and hiker deaths reported the previous week in the Italian Alps, mostly from avalanches. The snowpack is highly unstable due to recent heavy snowfall and strong winds laying unstable snow over weak layers. "Under such conditions, the passage of a single skier, or natural overloading from the weight of snow, can be sufficient to trigger an avalanche," said Federico Catania from Italy’s Alpine Rescue Corps. Category 5 avalanche warnings mean "numerous very large and extremely large natural avalanches" can occur, threatening valley roads and settlements. Skiers and mountaineers are advised to avoid all but the safest slopes. Luc Nicolino, slopes manager at La Plagne resort, described the snowpack as "a kind of mille-feuille with many hidden, fragile layers." Storm Nils last week dumped 60 to 100 cm of snow, with more snow expected. Among survivors was adventure skier Daniel Matthews, buried for eight minutes after a couloir collapsed beneath him on Friday. He shared on Instagram: "I made a very bad decision and uneducated decision to ski Skimans Couloir... The only person to blame is myself." He hopes others learn from his mistake. The Alpine region remains on high alert as heavy snowfall continues, and avalanche dangers persist.