Was the extreme rainfall that caused the August 2022 flood in Pakistan predictable?

Abstract

Pakistan suffered from severe floods in the past, but in August 2022, the country experienced exceptional extreme rainfall events that caused widespread and catastrophic flooding. The 2022 flood affected all aspects of socio-economic lives including agriculture, infrastructure, and mortality of humans and livestock. The two-day accumulated extreme rainfall on August 17-18 was anomalous and contributed the most to the flood in the southern provinces of Pakistan. The damage caused by extreme rainfall and the subsequent flooding has raised questions regarding the predictability of extreme rainfall by the existing weather forecasting models. Here, we use ensemble forecasts from four numerical weather prediction (NWP) models under THORPEX Interactive Grand Global Ensemble (TIGGE) datasets to examine the predictability of extreme rainfall at a six-day lead. The extreme precipitation during August 17-18, 2022 was predictable a week before the event that contributed the most to the flooding. All the forecast models provided an early warning at a six-day lead time. UKMO and ECMWF models produced comparable results to observations at all the lead times. Our findings highlight that an integrated framework of extended quantitative precipitation forecasts and hydrological modelling can help reduce the country's flood vulnerability and risk associated with it.

The impact of tropical sea surface temperature on extreme precipitation in Pakistan during the summer of 2022

“…The multi-day anomalously high rainfall began in July 2022, resulting in approximately double (180%) the long-term average rainfall for that month in Pakistan (Ma et al 2023, Qamer et al 2023. Subsequently, in August 2022, rainfall continued to increase, exceeding 500% of its climatology average, ultimately leading to extreme floods in Pakistan (Malik et al 2023). Heavy rains in Pakistan have caused nearly one-third of the country to be submerged, leading to the loss of 1700 lives and the displacement of 8 million people.…”