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Toyooka, D., T. Kawabata, H.L. Tanaka, 2024: Windward region sensitivity and its effects on heavy rainfall prediction investigated with ensemble systems. J. Meteor. Soc. Japan, 102.
https://doi.org/10.2151/jmsj.2024-008
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Graphical Abstract

Plain Language Summary: This study investigates the sensitivity of a heavy rainfall forecast in western Japan in July 2018. To identify the sensitive region, we conducted analyses of a backward trajectory and ensemble sensitivity, which consistently indicate that the moist air mass located windward played an important role in the forecast. Furthermore, observation system experiments show that the precipitation forecast is degraded without windward observations. These findings illustrate that the moist air mass near the Ryukyu Islands was transported by the Western Pacific Subtropical High in the lower troposphere, leading to the heavy rainfall.