On April 10, 2025, heavy rain and thunderstorms struck western Japan, causing significant disturbances, including a lightning accident on school grounds in Nara City. As the weather continued to develop, the Japan Meteorological Agency (JMA) issued warnings for unstable atmospheric conditions, particularly as moist air and cold air aloft combined to create tumultuous weather across the region.
On April 11, 2025, the JMA reported that the atmospheric conditions remained highly unstable, with warnings extending from the Kinki region to the Kanto region. Residents were cautioned about the potential for rapid weather changes, especially in the afternoon when localized thunderstorms could develop. The JMA noted that due to the instability, rain could come down heavily, accompanied by thunder, raising concerns for those in the affected areas.
Tokyo, along with neighboring prefectures such as Chiba, Kanagawa, and Ibaraki, faced a risk of heavy rain that could reach warning levels. By 11:00 AM on April 11, lightning warnings had been issued for 26 prefectures, covering areas from Shikoku to southern Tohoku. The JMA emphasized the importance of being prepared for sudden weather changes, advising residents to carry rain gear even when the skies appeared clear.
Furthermore, as the day progressed, the threat of severe weather intensified. The JMA highlighted that the atmospheric conditions would remain unstable, with the potential for thunderstorms and even tornadoes. The cold air descending from around 5,500 meters, with temperatures dipping below -21 degrees Celsius, contributed to the development of cumulonimbus clouds, which are known for their severe weather capabilities.
As the shear line moved southward across the Kanto region, rain clouds began to rapidly develop, particularly in Tokyo. Reports indicated that heavy rain was already beginning to fall in the capital, with forecasts predicting that rainfall could exceed 10mm in just 10 minutes, equating to over 60mm per hour. This could lead to temporary flooding on roads, posing risks for commuters and those out and about.
Safety measures were strongly advised, especially for outdoor activities. The JMA warned that if thunder was heard or lightning observed, it was crucial to seek shelter in a safe location, such as a reinforced concrete building or a vehicle with closed windows. Taking refuge under trees was particularly dangerous, as lightning strikes could occur even at a distance from the storm.
The situation remained dynamic throughout the day, with the potential for strong winds and hail also being a concern. Farmers and those involved in agriculture were advised to monitor the weather closely to protect crops and facilities from possible damage.
As evening approached, the JMA continued to issue alerts for the Kanto region, indicating that the unstable conditions would persist until around 8:00 PM in Tokyo and until approximately 9:00-10:00 PM in Kanagawa and Chiba prefectures. Residents were urged to stay informed and prepared as the weather evolved.
The combination of heavy rain, thunderstorms, and the possibility of tornadoes highlighted the need for vigilance in these areas. The JMA's warnings served as a reminder of the power of nature and the importance of heeding weather advisories to ensure safety.
In summary, the weather situation in Japan during this period exemplified the unpredictability of spring storms, with significant implications for daily life and safety. As citizens navigated the challenges posed by the weather, the importance of preparedness and awareness became ever more apparent.
