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Sueki, K., and Y. Kajikawa, 2019: Different precipitation systems between Hiroshima and Keihanshin during extreme rainfall event in western Japan in July 2018. J. Meteor. Soc. Japan, 97,1221-1232.
Special Edition on Extreme Rainfall Events in 2017 and 2018
https://doi.org/10.2151/jmsj.2019-063  Graphical Abstract with highlights

Plain Language Summary: During the heavy rainfall event in western Japan in July 2018, many differently-sized precipitation systems appeared one after another. This paper suggests that particularly large precipitation systems with areas of more than 10,000 km² increased the risk of deadly sediment disasters during the rainfall event. Such a large precipitation system occurred when the wind speed was significantly different between the lower and upper atmosphere.

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Highlights:

• During the heavy rainfall event in western Japan in July 2018, both the Hiroshima and Keihanshin areas were subjected to unusual rainfall amounts but their damages were significantly different.
• In the Hiroshima area where the number of sediment disasters was significantly larger, rainfall caused by large precipitation systems with areas equal to or larger than 10⁴ km² were dominant.
• Such a large precipitation system occurred under the condition that vertical wind shear in the 0.5–6.0 km above ground level layer was relatively large.