UEF2021: A special event in an extraordinary year

Becky Hemingway


Using ECMWF's Forecasts (UEF2021) was held virtually from 1 to 4 June 2021. The second fully virtual UEF event attracted people from all over the world to discuss and provide feedback on ECMWF products and services.

The theme of UEF2021, 'Weather in extraordinary circumstances', aimed to encompass not only the extraordinary circumstances of 2020/21 and their impact but other extraordinary events which impact forecasting, modelling, users and the public. Four thematic areas were covered: 'Severe weather and hazard forecasting'; 'Forecasting in extraordinary circumstances'; 'Unforeseen impacts of extraordinary circumstance', and 'Extraordinary collaborations'. There was also a special session run by Nuno Moreira from IPMA (Instituto Português do Mar e da Atmosfera) on 'Recent developments in assessing societal impacts of extreme meteorological events at a national level'.

In addition to oral presentations on the thematic areas and updates from ECMWF, UEF2021 featured a number of new elements, including the first 'Copernicus Day' focused on the EU's Copernicus services linked to ECMWF, five-minute 'lightning talks' on a variety of topics, and a Science and Art event. Networking opportunities and interactive events were enhanced using the platform. The User Voice Corner, poster sessions, networking breaks, a social event and feedback and discussion sessions were all held in the platform.

UEF2021 group photo
UEF2021 virtual group photo. Attendees were invited to submit photos of themselves for the UEF2021 group photo instead of the usual photo around the ECMWF fountain.

Meeting highlights

ECMWF Director of Forecasts Florian Pappenberger presented the ECMWF Strategy 2021–2030 (https://, which sets out a number of exciting projects. These include machine learning, the European Weather Cloud, Destination Earth, Copernicus services, Open Data, Bologna Our New Datacentre (BOND), and Bonn hosting the new ECMWF facility. Richard Forbes (ECMWF) presented the changes to be implemented in the next model cycle (47r3), including improved visibility forecasts and new products for Convective Available Potential Energy (CAPE) and Convective Inhibition (CIN). Thomas Haiden (ECMWF) showed improved verification scores due to recent model upgrades, including the highest ever ensemble skill in the upper-air and highest skill so far for the 5-day Extreme Forecast Index (EFI).

As part of the thematic presentations, authors presented on a range of activities and tools which help users and forecasters better understand and forecast extreme weather and its impacts. Natalia Korhonen (Finnish Meteorological Institute) showed that ECMWF temperature re-forecasts were the most skilful in predicting the life cycle of a heatwave. Parmoita Chakraborty from the National Centre for Medium Range Weather Forecasting (NCMRWF), India, showed an interesting comparison of ECMWF, NCMRWF and US Global Ensemble Forecast System (GEFS) models for tropical cyclone Amphan. Anastasita Stycheva's (National Institute of Meteorology and Hydrology, Bulgaria) poster discussed intense dust events in Bulgaria and how ECMWF products can be used to forecast these.

With impact-based forecasting becoming more prevalent, Joanne Robbins (UK Met Office) discussed how impact data is collected and the difficulties in processing it to make it useable for forecast evaluation. The presentation sparked a lively discussion between attendees during the special session. Min-Jeong Youn's (Korean Meteorological Agency/UK Met Office) poster complemented this by demonstrating how impact-based forecasting can be used to forecast heatwave impacts in South Korea.

Effects of COVID-19 on the meteorological community also featured. Bruce Ingleby (ECMWF) presented an unforeseen impact of COVID-19: reduced aircraft observation data due to a drop in aircraft numbers resulting in large impacts on wind forecasts. However, model verification scores did not appear to be affected and alternative data sources were discussed. Marc Guevara (Barcelona Supercomputing Center) showed emissions from different sectors and how they changed during the COVID-19 pandemic to quantify the impact of lockdown policies.

Copernicus Day was dedicated to showcasing the variety of products and services of the Copernicus Atmosphere Monitoring Service (CAMS) and the Copernicus Climate Change Service (C3S), which are run by ECMWF, as well as the Copernicus  Emergency Management Service (CEMS), to which ECMWF contributes. Stylianos Kotsopoulos (AGROAPPS P.C.) demonstrated a tool which uses Climate Data Service (CDS) data to aid the agriculture sector with cultivation planning. The final part of the day focused on the forecast–predictions–projections nexus, with presentations demonstrating how sub-seasonal to seasonal predictions can aid shorter lead-time forecasting by utilising sources of predictability.

The five-minute 'lightning talks' were well received, covering topics such as the ECMWF unified support portal, ECMWF Summer Weather of Code (EWSoC) 2021, user-orientated forecast system development, the Severe Event Catalogue and ECMWF Learning Resources.

One lightning talk launched the Forecast User Forum ( The forum offers a platform for users of ECMWF forecasts around the world to discuss current and recent weather and forecasts. It widens the opportunities to provide feedback to ECMWF beyond events like the UEF.

User survey results

Prior to UEF2021, users were asked to complete two surveys: the annual User Voice Corner survey, and an ECMWF's extended-range graphical products survey. Tim Hewson (ECMWF) presented the results of both surveys during UEF2021.

The User Voice Corner survey's outcomes showed that satisfaction with ECMWF forecasts and products is generally very high, with short-range to seasonal forecasts all heavily utilised and a number of notably good forecasts cited. Issues with certain forecast fields, e.g. precipitation, in particular geographic areas were highlighted by users. Awareness of user-orientated documentation was shown to be generally very good.

The ECMWF extended-range graphical products survey showed users regularly use a range of extended- range products, particularly maps of ensemble mean anomalies, the extended-range Extreme Forecast Index (EFI), and meteograms. However, many users would like to understand products better. The survey results will be used to inform a major update to extended-range forecasting.

Interaction in

The platform was used to provide all interactive activities at UEF2021 and to facilitate networking opportunities for attendees. It was the first time the platform had been used at a UEF event, and positive feedback was received.
UEF2021 avatar group photo. All those in were invited to come together for a virtual ‘group photo’ with their avatar character around the ECMWF duck fountain in the virtual ECMWF office environment.

Participants liked how they could easily interact with other attendees by avatars getting close to each other. Audio and video were then connected, facilitating a conversation.

Attendees provided positive feedback on the event: "Well done on organizing and facilitating an excellent and informative meeting. I really enjoyed it."; "Thank you so much for the huge amount of products which are the result of the great work of the ECMWF people. Thank you for organizing UEF 2021!"; and "UEF meetings are a very good concept and the UEF 2021 was an excellent meeting. It was well organized, interactive, positive and informative."

All the presentations, posters and session recordings are available on the ECMWF website at:​

Science and Art Event at UEF2021: Artwork by Louise Arnal as part of the Virtual Water Gallery.

Art and Science event

Science and art are two things not usually seen as closely associated. The Science and Art event at UEF2021 wanted to dispel this by showcasing science-inspired artwork. Art can also be used to display one's own work in order to engage audiences on platforms used to promote science. Louise Arnal (University of Saskatchewan) and Chloe Brimicombe (ECMWF) presented their artwork and their scientific influences. Their presentations provided fascinating insights into why art and science should be interconnected.

The event was held in a art exhibition space, with artwork also contributed by Milana Vučković (ECMWF) and Loriano Pagni (ECMWF). It followed on from a successful Science and Art Exhibition at ECMWF in 2020. ECMWF hopes to continue these events in the future.