July 27, 2026

The 2026 Atmospheric River Reconnaissance (AR Recon) Workshop, hosted at the European Centre for Medium-Range Weather Forecasts (ECMWF), took place in Reading, UK, on June 29th and 30th, 2026. The AR Recon Workshop was hosted alongside the 2nd Observational campaigns workshop for better weather forecasts, encouraging researchers to attend two workshops aimed at improving weather forecasts back-to-back, and providing a broader setting for the reporting on the first demonstration of AR Recon’s expansion into the Global Atmospheric River Reconnaissance Program (GARRP). These events brought together AR Recon partners, experts, stakeholders, and researchers involved in other field campaigns from across the globe to discuss prior achievements, recent advancements, coordinate future efforts, and explore methods to enhance collaborative research on atmospheric rivers and related essential atmospheric structures.

The two-day workshop featured presentations and panel conversations from AR Recon collaborators involved in planning research flights, executing sampling missions, and analyzing the voluminous data collected during the season. The 2026 workshop also featured discussions about the first successful GARRP season, highlighting the expanded coordination between AR Recon and other field campaigns to collect observations in atmospheric rivers across the northern hemisphere, which are meant to improve forecasts at extended lead times. The coordination across the field campaigns through GARRP this past season laid the foundation for continued collaboration between AR Recon and other field campaigns with an eye to future years of continued success.

Florian Pappenberger, Director-General of ECMWF, delivered a welcome address emphasizing the importance of AR Recon as part of the global observing system, underscoring how vital these field campaigns are to improving forecasts and saving lives. Marty Ralph, Director of CW3E and PI of AR Recon and GARRP, gave a keynote address on the growth of AR Recon over the years, how operational partners and government stakeholders have made it possible for the campaign to thrive into a leader in its field. He discussed how it serves as a hotbed for testing out new technologies and advancing scientific research, paving the way for further expansion in the coming years. Other speakers featured were Lt Col Ryan Rickert, US Air Force Reserve Command 53rd WRS, Nikki Hathaway, NOAA Aircraft Operations Center, and David Lavers, ECMWF. The full agenda, including presentation slides and recordings, can be found online here via the ECMWF events website.

The workshops included both in person & virtual presentations, a poster session, and a closing panel discussion on the present and future of operational field campaigns. Presentations featured sharings on the latest findings in atmospheric river research, results from recent studies, new data assimilation and modeling technologies, operational strategy discussions, and extensive collaboration across different agencies and programs. Participants discussed improvements and innovations in atmospheric data collection, with representatives from all AR Recon observing platforms giving presentations. This includes the Global Drifter Program (Lagrangian Drifter Laboratory), Global Sounding Balloons (WindBorne Systems), Airborne Radio Occultation (ARO, Scripps PI Jennifer Haase), mobile radar development and deployment (Jon Rutz/CW3E & Jana Houser/Ohio State University), moored buoy observations (the Office of Naval Research (ONR)’s Sea Air Fluxes and Atmospheric River Initiation (SAFARI) Departmental Research Initiative), radiosonde observing networks (CW3E/AR Recon-Coordinated University Sounding Program (ARR-CUSP)) and satellite observations (NASA Jet Propulsion Laboratory). Furthermore, partners gave presentations on numerical weather prediction models and forecast verification efforts (NOAA/NWS/Office of Modeling and Development, ECMWF, US Naval Research Laboratory, CW3E, and UMass Amherst).

The 2nd Observational Campaigns Workshop for better weather forecasts followed the AR Recon Workshop, and was an opportunity for researchers from field campaigns across the Northern Hemisphere to come together and discuss the details of each unique campaign. GARRP was a central focus of this workshop, with NASA’s NURTURE campaign, collaborative European program NAWDIC, and the US ONR’s SAFARI program each presenting on the research conducted underneath the GARRP umbrella. These three were the primary field campaigns which came together this past year under the leadership of CW3E and AR Recon to coordinate Northern Hemispheric sampling strategies with the goal of improving week two forecasts. Truly an international effort, partner agencies, institutions, and field campaigns from around the world were highlighted, fostering an environment for further interconnectedness within the global field campaign community in the future.

As AR Recon enters its 2026-27 season, the program continues to build on its prior successes and demonstrate value to the United States through improved precipitation forecasts and to the global weather community through enhanced understanding of the physical processes associated with ARs. The successful GARRP demonstration this past winter provided the first opportunity to illustrate the value of the program as a critical part of the global observing network. Discussions during the week jump-started assessments into forecast impact and addressing process-based science questions. By increasing data collection within atmospheric rivers and associated essential atmospheric structures across the Northern Hemisphere, AR Recon and GARRP as a whole are using state-of-the-art targeting strategies to comprehensively fill gaps in the conventional observing system, adding value to weather forecasting and in turn, emergency response and water management across the United States and the world.