New model improves forecast of extreme rainfall

New research from an international team of climate experts shows that intense, localised, heavy rainfall can be caused by rapid air rise through clouds, and proves that this air rise is predictable. The team has developed a unique, state-of-the-art modelling system that marks a fundamental shift in the way we identify and predict life-threatening, short-duration, extreme rainfall. Better prediction of these intense rainfall events will help buy communities crucial time to prepare for extreme weather conditions that can lead to devastating flash floods, such as those seen in Boscastle in August 2004 or London in August 2022.

Published in the journal Weather and climate extremesThe study was led by the Met Office and Newcastle University, with support from the Universidad de Costa Rica, San Jose, Costa Rica and Adam Mickiewicz University, Poznan, Poland.

Paul Davies, lead author of the study, Principal Fellow of the Met Office and Visiting Professor at the School of Engineering at Newcastle University, said: “The new model aims to improve the UK's resilience to extreme weather events, which are becoming more frequent and intense due to climate change. This approach addresses the urgent need for improved forecasting capabilities and will help both the UK and the global community mitigate the risks associated with increasingly extreme weather events.”

Paul added: “To understand these extreme precipitation events, we made an exciting discovery: the presence of a three-layer atmospheric structure consisting of moist, highly unstable layers sandwiched between a stable upper layer and a nearly stable lower layer.”

The new research focuses on the atmospheric properties of the extreme rainfall environment, with particular attention to the thermodynamics associated with the less than hourly rainfall processes. It identifies a distinct three-layer atmospheric structure that is critical for understanding local rainfall and associated large-scale atmospheric regimes, and could enable further prediction of the occurrence of extreme rainfall and flash floods.

Hayley Fowler, co-author of the study and Professor of Climate Change Impacts at Newcastle University, added: “I am delighted to be helping to lead such exciting new research that is enabling a paradigm shift in thinking about extreme rainfall processes. We will develop this model into a deployable system that can help meet the UN's call for early warning for all, which aims to ensure universal protection from dangerous weather, water or climate events through life-saving early warning systems by the end of 2027. As human-caused climate change leads to more extreme weather conditions, the need for accurate early warning systems is now more important than ever.”

This research has the potential to develop an extreme rainfall warning system that will enable meteorologists and users to detect and predict dangerous flash floods, improving public safety and preparedness.