Environmental Features of Heavy Precipitation Under Favorable Synoptic Patterns: A Lesson from the 2021 Henan Extreme Precipitation Event

In July 2021, a catastrophic extreme precipitation (EP) event occurred in Henan Province, China, resulting in considerable human and economic losses. The synoptic pattern during this event is distinctive, characterized by the presence of two typhoons and substantial water transport into Henan. However, a favorable synoptic pattern only does not guarantee the occurrence of heavy precipitation in Henan. This study investigates the key environmental features critical for EP under similar synoptic patterns to the 2021 Henan extreme event. It is found that cold clouds are better aggregated on EP days, accompanied by beneficial environment features like enhanced moisture conditions, stronger updrafts, and greater atmospheric instability. The temporal evolution of these environmental features shows a leading signal by one to three days. These results suggest the importance of combining the synoptic pattern and environmental features in the forecasting of heavy precipitation events.