「『秋雨前線＋太平洋高気圧＋台風』この3つが揃うと豪雨になる」片平気象予報士が解説　「雨前線が関西に停滞すると同じように大雨になる恐れがある」　北陸で相次ぐも…“どこでも起こりうる”豪雨

Heavy rains have been occurring in the Hokuriku region since last week. Meteorologist Atsushi Katahira provided an explanation of the current situation. He stated that "when the autumn rain front, the Pacific high-pressure system, and a typhoon all align, torrential rain occurs," and pointed out that this could also happen in other regions such as Kansai if the autumn rain front remains stationary. ■ Heavy Rains Caused by "Autumn Rain Front + Pacific High-Pressure System + Typhoon" Flooding has occurred in Ishikawa, Toyama, and Fukui prefectures, and as of today, August 31st, some areas are still flooded. There is a risk of further heavy rain later this week, and vigilance remains high. Meteorologist Atsushi Katahira explains that "when the autumn rain front, the Pacific high-pressure system, and a typhoon all align, torrential rain occurs." 【Atsushi Katahira, Meteorologist】 Last Thursday, August 27th, a Level 5 heavy rain special warning was issued for Ishikawa and Toyama prefectures. Looking at the weather map for that day, the autumn rain front, a band of rain clouds, extended over the Tohoku and Hokuriku regions. ■The moist air from the typhoon was pumped into the autumn rain front by the Pacific high-pressure system… Because typhoons originate in the tropics, they carry a large amount of moist air around them. The Pacific high-pressure system acted like a pump, sending this moist air towards the autumn rain front. It is believed that this continuous supply of rain cloud material led to the record-breaking heavy rainfall in the Hokuriku region. Subsequently, the autumn rain front moved south on Friday (28th), bringing severe thunderstorms to the Kinki region. On Sunday (30th), it moved north again towards the Hokuriku region, causing heavy rain in Fukui Prefecture. Today, August 31st, the front's activity has weakened, but caution is still necessary. ■ Small and medium-sized rivers become dangerous almost immediately after the rain begins Furthermore, during this heavy rain, there were numerous cases of small rivers overflowing rapidly in a short period of time, within 1-2 hours. While there is a time lag before large rivers overflow, small and medium-sized rivers become dangerous almost immediately after the rain begins. With rain patterns changing, it is important to be careful when making decisions based solely on past experience. Also, during heavy rain, be aware of flooding in low-lying areas, poor drainage, and dangerous underpasses. ■ Heavy rain can occur anywhere a front is stalled The autumn rain front is located at the boundary between autumn and summer air, and therefore generally remains near Japan until around September, when autumn truly arrives. This time, the Hokuriku region experienced heavy rain, but if the front stalls over the Kansai region, similar heavy rain could occur there as well. Tomorrow, September 1st, the autumn rain front is expected to extend over the Sea of ​​Japan, bringing in warm, humid air. The weather will be partly sunny and partly cloudy, with a possibility of scattered showers, mainly in the morning. ■Intense Lingering Heat…Some Areas Reach 38 Degrees Celsius Even in September Some areas, such as Toyooka, are expected to reach a maximum temperature of 38 degrees Celsius, potentially experiencing extreme heat. This week, the intense heat will continue until around Wednesday, with rain expected on Thursday and Friday. The heat is expected to subside somewhat from this weekend onwards. (Kansai TV "news runner," broadcast August 31, 2026)