As climate change intensifies hydrometeorological extremes worldwide, cities are becoming increasingly vulnerable to extreme rainfall and urban flooding. Hong Kong has experienced more frequent and intense precipitation events in recent years, including the unprecedented black rainstorm in September 2023, which exposed critical vulnerabilities in urban infrastructure and community preparedness. Against this backdrop, the 9th Convection-Permitting Climate Modeling (CPCM) Workshop provided an international platform for advancing scientific understanding and collaborative responses to extreme urban precipitation.

The workshop was co-organized by the HKUST, WMO World Weather Research Programme (WWRP), the WMO World Climate Research Programme (WCRP), GEWEX, CORDEX, and the Hong Kong Observatory, reflecting strong institutional support from the World Meteorological Organization and its affiliated research programmes. The meeting also marked the first time the CPCM Workshop was held physically in Asia, highlighting the increasing importance of tropical and coastal regions in convection-permitting climate modeling research.

Participants included leading researchers from mainland China, Hong Kong, and 13 other countries, including Australia, Canada, Denmark, Finland, Italy, Japan, the Philippines, South Korea, Sweden, Switzerland, Thailand, the United Kingdom, and the United States. Many attendees represented national meteorological services and major numerical weather prediction (NWP) modeling teams responsible for developing the operational forecasting systems used by weather services worldwide. The workshop therefore served as a rare global gathering of experts shaping the scientific and technical direction of extreme precipitation research and urban climate prediction.

Notably, the workshop coincided with an extraordinary rainfall event in Hong Kong. On 5 August 2025, the Hong Kong Observatory issued the fourth Black Rainstorm Warning within the same year, with 368.9 mm of rainfall recorded in a single day, the highest August daily rainfall since records began in 1884. The workshop temporarily moved online during the storm, offering participants a vivid real-time illustration of the challenges being discussed and underscoring the urgency of improving prediction and preparedness for extreme precipitation events.

Event Photo Gallery: https://www.flickr.com/photos/50763757@N03/albums/72177720328553354