Final score of the 10th Anniversary HEPEX Workshop

Contributed by Maria-Helena Ramos, Fredrik Wetterhall, Andy Wood, JuttaThielen, Florian Pappenberger, Jan Verkade

and-the-winner-isIn these times of World Cup, you may have heard many times the key question: “So, who’s the winner?”

At the end of the 10th Anniversary HEPEX Workshop, we can definitely claim that ensemble predictions have won the hydrological forecasting competition for better and reliable forecasts. A feeling shared by scientists, operational forecasters, forecast users, students and young researchers that participated to this event (see the group photo here):  ensemble forecasts are here to stay!

The workshop provided us with a review of achievements, gaps and new opportunities for ensemble prediction, as well as new co-chairs for the HEPEX initiative, as shown below.

The workshop


Participants during a visit to the new NCEP center in Maryland that hosted the 10th Anniversary Workshop

From 24-26th June, more than 70 scientists came together in the new NCEP Center in Maryland to listen to lectures and share ideas on the techniques and uses of ensemble predictions for flood forecasting, droughts and water resource management. A further 30 followed the meeting online, via a webcast and twitter.

Participants proposed reviews of achievements in hydrological probabilistic forecasting as well as case-studies illustrating user-focused applications and a variety of ways to communicate and use ensemble forecasts when making decisions.


Stats from the HEPEX website: weekly number of views, showing the peak of views during the week 23-29 June when the home page was the Twitter feed on live during the 10th Anniversary Workshop

What is working well? What are the major pressing gaps? What are the major opportunities?

These questions were worked out during the workshop and the answers converge to indicate that:

  • skill in probabilistic forecasts has improved considerably and computational time has dropped making the use of ensemble predictions more feasible in operational applications;
  • for sophisticated users, the HEPEX community has made the case that ensemble forecasts do inform risk-based decision making;
  • the development of end-to-end systems is on the rise: the more agencies use the forecasts, the more they become comfortable with ensemble forecasts;


    Jan Verkade’s presentation explaining ‘Hepex online’. Download it here.

  • communication to users is getting much better and communication between meteorologists and hydrologists has also improved markedly;
  • the science has converged on a framework of elements (such as post-processing) that are needed in ensemble forecast systems, and our understanding of these elements is steadily growing.

Gaps however remain, shaping the way to new opportunities:

  • expertise is still needed in converting knowledge into decisions;
  • some users are still not sufficiently involved in the development of probabilistic information: more interaction between developers/researchers and users is still needed;
  • gaining confidence in the forecasting and observation of severe events is still an issue that deserves particular attention;
  • understanding forecast verification is a considerable challenge for users: case-studies and user-focused forecast evaluation may facilitate the adoption of ensemble predictions by a larger community of users;
  • learn by doing: training is a real opportunity to improve the uptake of ensemble predictions by forecasters and end users;
  • it is important to get all actors involved in the probabilistic forecasting chain: we need to engage with sophisticated users with decision support systems to drive innovative applications and contribute in building new decision-making protocols, more adapted to the probabilistic context.

New co-chairs in HEPEX and advisory board

The workshop was also the occasion to welcome new co-chairs and a regional chair for Europe:

  • Maria-Helena Ramos (IRSTEA), co-chair
  • Fredrik Wetterhall (ECMWF), co-chair
  • Jan Verkade (Deltares), regional chair for Europe

New co-chairs will join Andy Wood (UCAR), also a HEPEX co-chair, and will be helped in their tasks of promoting HEPEX worldwide by an advisory board, which is composed by ‘old’ chairs and people who has been for so long part of the HEPEX adventure:

  • John Schaake (Consultant)
  • Roberto Buizza (ECMWF)
  • Jutta Thielen (JRC)
  • Florian Pappenberger (ECMWF)
  • Robert Hartman (NWS)


Feedback on HEPEX received so far shows that it is the interdisciplinary mix of enthusiastic people working to improve predictions to the wide community of forecast users that makes HEPEX works so well. HEPEX activities (meetings, webinars, blog posts, etc.) motivate people to pursue their research on ensembles and exchange their results with its large community of researchers and practitioners, which currently counts more than 300 members.

We hope this will continue and grow further for another 10 years or more!


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