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Main Authors: Chan, P. W., Kwok, Y. T.
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2508.07600
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author Chan, P. W.
Kwok, Y. T.
author_facet Chan, P. W.
Kwok, Y. T.
contents Four episodes of black rainstorms, the highest tier of heavy rain according to the rainstorm warning system in Hong Kong, occurred within eight days from 29 July to 5 August 2025, breaking the record for torrential rain in the territory. Providing early alerts to the public about these black rainstorms has considerable application value and has a substantial impact on their lives. This initial review of the four black rainstorm cases focuses on the predictability of the events from the synoptic/mesoscale to the micro/storm scale. A newly available tool for three-dimensional wind fields retrieved from weather radars in the region was used to analyse the triggering factors for the development and maintenance of intense convection. Given the current level of technology, the four episodes of heavy rain had different degrees of predictability. Global artificial intelligence (AI) models were found to be skilful in capturing two major rainstorms, including one week before they occurred. Surface convergence, mid-tropospheric waves, and jets were important mechanisms in heavy rainfall occurrence. Future research directions on these black rainstorms have been briefly discussed.
format Preprint
id arxiv_https___arxiv_org_abs_2508_07600
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A historical record of four black rainstorm episodes in Hong Kong, China in July to August 2025
Chan, P. W.
Kwok, Y. T.
Atmospheric and Oceanic Physics
Four episodes of black rainstorms, the highest tier of heavy rain according to the rainstorm warning system in Hong Kong, occurred within eight days from 29 July to 5 August 2025, breaking the record for torrential rain in the territory. Providing early alerts to the public about these black rainstorms has considerable application value and has a substantial impact on their lives. This initial review of the four black rainstorm cases focuses on the predictability of the events from the synoptic/mesoscale to the micro/storm scale. A newly available tool for three-dimensional wind fields retrieved from weather radars in the region was used to analyse the triggering factors for the development and maintenance of intense convection. Given the current level of technology, the four episodes of heavy rain had different degrees of predictability. Global artificial intelligence (AI) models were found to be skilful in capturing two major rainstorms, including one week before they occurred. Surface convergence, mid-tropospheric waves, and jets were important mechanisms in heavy rainfall occurrence. Future research directions on these black rainstorms have been briefly discussed.
title A historical record of four black rainstorm episodes in Hong Kong, China in July to August 2025
topic Atmospheric and Oceanic Physics
url https://arxiv.org/abs/2508.07600