Dry Intrusion Connects High-Impact Cyclones Eunice and Franklin: Emerging Observational Targets of NAWDIC

Midlatitude winter storms cause substantial socioeconomic impact through strong winds and heavy precipitation. Challenges remain in understanding the multiscale dynamics of these systems and accurately predicting their impacts. New observational and modeling capabilities enable tackling these challenges and motivate the “North Atlantic Waveguide, Dry Intrusion, and Downstream Impact Campaign (NAWDIC)” scheduled for winter 2025/26. We present a case study of two high-impact winter cyclones, Eunice and Franklin, in February 2022 to illustrate the interacting processes across scales. First, Eunice brought damaging wind gusts, and subsequently Franklin caused heavy precipitation and flooding. Both systems and their impacts were linked in a Lagrangian sense through a dry intrusion (DI) airstream. The descending DI reaching the cold sector of Eunice produced gale force winds and strong ocean evaporation leading to a rapid moistening of the originally dry air mass. These moistened air masses were transported westward around the subtropical anticyclone before feeding an atmospheric river over the North Atlantic 2 days later. As the air masses ascended in the warm conveyor belt of cyclone Franklin, they caused heavy precipitation and flooding across the British Isles. ... mehrBased on the case study, we highlight existing observational gaps potentially leading to forecast uncertainties. Finally, we emphasize the need for the internationally coordinated NAWDIC airborne campaign and present measurement strategies aimed at improving our understanding of the coupled multiscale processes leading to high-impact weather.