The Japan Meteorological Agency issued Level-5 heavy-rain warnings for parts of Toyama and Ishikawa prefectures on Thursday after a line-shaped rain band formed [1, 4].
These warnings represent the highest level of alert in Japan, signaling an immediate threat to life and property. The extreme weather increases the risk of catastrophic landslides and river flooding in mountainous and coastal regions.
The weather system developed as an autumn rain front moved over the Hokuriku region [6, 7]. This front generated a concentrated band of intense precipitation that stalled over western Toyama and Ishikawa. In Himi City, Toyama, the agency recorded 180 mm of rain over a six-hour period [4], which the agency said was the highest amount ever recorded in the city's observation history [2].
Emergency alerts began early Thursday morning. The Toyama regional office issued an alert at 02:58 JST [1], followed by an alert from the Kanazawa regional office in Ishikawa at 03:08 JST [1]. Later in the morning, a specific announcement regarding a line-shaped rain band in the Kaga region of Ishikawa was issued at 08:48 JST [3].
Level-5 special warnings were specifically issued for the municipalities of Hakui, Hōtatsu-Shimizu, Nakanoto, and Shika [4]. The Japan Meteorological Agency said the danger of disasters that could threaten lives is increasing rapidly [1].
Local authorities have urged residents in affected areas to seek immediate shelter. The agency warned that the intensity of the rainfall could lead to sudden flash floods and slope failures, events that often occur without warning in the Hokuriku terrain.
“"The danger of disasters that could threaten lives is increasing rapidly."”
The occurrence of a line-shaped rain band during the autumn rain front season highlights the increasing volatility of weather patterns in the Hokuriku region. Because this specific meteorological phenomenon causes extreme rainfall to concentrate in a narrow area for extended periods, it often overwhelms local drainage and slope stabilization efforts, making Level-5 warnings critical for preventing mass casualty events in rural prefectures.
