Authorities in Japan issued flood and landslide warnings across the affected areas after a tropical storm slammed into Japan's main island early Tuesday, bringing violent gusts and downpours that have already caused rivers to surge.
Despite being downgraded from a typhoon, Lan nevertheless raced in from the Pacific, aiming for the commercial centres of Osaka and Kobe while packing gusts of up to 144 km/h (90 mph), torrential rain, and high waves.
According to the Japan Meteorological Agency, it made landfall on the main island of Honshu shortly before 5am (2000 GMT) near Wakayama prefecture, roughly 600 kilometres (375 miles) west of Tokyo.
The organisation suggested that some locations could see up to 35 centimetres of rain in the 24 hours leading up to Wednesday morning.
"The typhoon's speed is slow and the duration of its impact in (central and western regions) could become extended. The total rainfall (in some areas) may exceed the average monthly rainfall in August," the weather agency tweeted.
"Please exercise extreme caution against landslides, surging water in low-lying areas, swollen and flooded rivers and violent winds," the weather agency said in a warning issued for numerous areas.
At least 50,000 households in seven regions had lost power as of Tuesday morning, according to a local utility, AFP reported.
Flying debris stopped local commuter trains, while flights and express trains were suspended as planned.
Local governments issued non-compulsory evacuation instructions to more than 180,000 residents, especially in Wakayama, Kyoto and the ancient capital of Nara.
The weather system was set to spend all of Tuesday sweeping over the region, before moving out to the Sea of Japan.