Correlation between Precipitable Water Vapor and heavy rainfall over a semi-mountainous area in Cyprus

Nowcasting and understanding of locally evolving severe weather events is a demanding task that requires the combined investigation of different type (both ground-and space-based) of datasets.Atmospheric water vapor (WV) which is the most abundant greenhouse gas (accounting for ~70% of global warming) comprises a significant energy source which generates severe weather and climate phenomena.The rapid spatiotemporal variations of WV in the low atmosphere poses one of the main challenges to NWP models forecasting accuracy.Abrupt increase of WV several hours before extreme rainfall has been temporally correlated with rainfall in various studies, followed by a decrease after the event.Other studies have investigated the joint effect of WV and atmospheric pressure on extreme rainfall.Though many studies have evidenced ongoing accumulation of WV before the heavy rainfall, there is still a great difficult to determine a tight relationship between rainfall and WV, that could be reproduced by a plain, physically motivated two-layer nowcasting model.In this context, the present study attempts a first comparison of Precipitable Water Vapor with the respective rainfall measurements with the ultimate aim to investigate the possible correlation between WV and heavy rainfall, during a selected extreme precipitation event occurring during 19-31 December 2024 over a semimountainous area in Cyprus Island.To achieve this, we exploited ERA5 Reanalysis dataset and rainfall observations over Xyliatos meteorological station (35.0295N, 33.0436 E), owned by the Department of Meteorology of Cyprus.