Typhoon 15 is moving west across the Japanese archipelago and is expected to weaken into a tropical depression over the San'in offshore region [1, 2].

The storm's path brings significant risks of landslides and rising river levels across multiple regions, forcing authorities to issue widespread weather alerts.

The system made landfall in southern Ibaraki Prefecture at approximately 8 p.m. on Tuesday [1, 3]. While some reports indicated the landing would be a historic first for the area, other reports confirmed the event had already occurred [1, 2].

Forecasters expect the storm to bring intense rain and strong winds to a wide area, including the San'in, Kinki, Tokai, Kanto, and Tohoku Pacific coast regions [1, 2]. Wind speeds are expected to reach 15 meters per second or higher [1].

Expected rainfall over a 24-hour period is estimated between 100 and 150 millimeters [1]. The severe weather has already impacted local events, including the cancellation of 6,000 fireworks [4].

"Typhoon 15 is expected to move toward the San'in offshore region by early afternoon and change into a tropical depression," a TBS NEWS DIG announcer said [1].

Meteorologists said that as the typhoon moves west, it is colliding with cold air in the upper atmosphere. This interaction creates atmospheric instability, which generates the heavy precipitation and wind—even as the storm's overall intensity weakens into a depression [1, 2].

Authorities continue to warn residents of the potential for flash flooding and mudslides. Additionally, weather services said that another typhoon could form by Wednesday [1, 2].

"Typhoon 15 made landfall in southern Ibaraki Prefecture around 8 p.m. yesterday, the 11th, and has continued to move west," the TBS NEWS DIG announcer said [1].

“Wind speeds are expected to reach 15 meters per second or higher.”

The transition of Typhoon 15 into a tropical depression does not signify an end to the danger. The collision with upper-level cold air maintains the system's ability to produce hazardous rainfall and wind across Honshu. The possibility of a subsequent typhoon forming immediately after this event suggests a period of heightened meteorological volatility for the region.