残雪に強風 稜線は厳冬期の様相

Mount Poroshiri summit currently holds 68cm of snow, with temperatures below freezing. The daytime wind chill feels like -8°C or colder. While the base experiences spring-like conditions above 10°C, the summit retains a distinct winter character. The ground is expected to be a mix of residual snow and wind-hardened ice, necessitating crampons and an ice axe. Especially within the unique cirque topography of the Hidaka Mountains, strong winds create extensively frozen and hard snow surfaces.

For routes involving river crossings, such as the Nukai-gawa course with over 20 crossings, the rising temperatures at the base could lead to increased meltwater and swollen rivers. This surge in water volume would significantly complicate passage. Avoid attempting risky crossings and be prepared to turn back if conditions are too challenging.

Although the forecast for tonight and early morning is clear, wind speeds are expected to exceed 10m/s, with gusts over 30m/s. This combination of strong winds and sub-zero temperatures will drive the wind chill down to approximately -14°C. Moving on exposed ridges carries an extremely high risk of hypothermia and loss of balance, demanding a very cautious assessment of whether to proceed. Essential layering includes a merino wool base, fleece and light down mid-layers, and a waterproof-breathable shell paired with a thick down jacket as outer layers.