立山晴天 残雪締まり歩きやすいが防寒を

Current conditions on Tateyama (Oyama) are mostly clear, with a summit temperature of -0.3°C and a feels-like temperature of -3.7°C. Winds are very light, and visibility is excellent. Clear to partly cloudy skies with light winds will persist throughout the day. The temperature difference between the summit and base is approximately 3.5°C, emphasizing the consistently harsh environment of the 3000m alpine ridge.

The current snow depth is 196cm. The snow surface is hard and firm in the morning, posing a high risk of slipping, especially on the route from Ichinokoshi to Oyama Summit where icy sections are present. Crampons and an ice axe are essential; microspikes are insufficient. While the snow may soften slightly during the day due to rising temperatures, the high altitude means it will mostly remain firm or become granular, with a mix of residual snow and exposed rock sections throughout the day. Rockfall risk is not zero but is considered limited given today's temperatures.

As indicated by the automated risk assessment, a sharp temperature drop of 7°C is expected during the forecast period. Be prepared for sudden changes in conditions by carrying an extra thermal layer from the outset. Summit feels-like temperatures will remain below freezing throughout the day, so a wicking base layer, fleece or light down mid-layer, and windproof/waterproof outer shell are fundamental. Temperatures are projected to plummet to -4.4°C overnight.

Aim to conclude all activities by 3 PM at the latest, and be ready to turn back early. Severe vigilance against hypothermia, common in 3000m class mountains, is required. Today's activities should capitalize on the fair weather while maintaining a cautious approach, mindful of the inherent challenges of spring mountaineering in a high alpine environment.