A Hydrologist’s guide to the CRPS

Title
A Hydrologist’s guide to the CRPS
Technical memorandum
Date Published
12/2025
Secondary Title
Technical Memoranda
Number
935
Author
Karan Ruparell
Kieran Hunt
Hannah Cloke
Christel Prudhomme
Florian Pappenberger
Matthew Chantry
Publisher
ECMWF
Abstract The Continuous Ranked Probability Score (CRPS) is a vital metric in earth system forecasting, how-ever it is still unintuitive for many users. In hydrology, we are increasingly transitioning to proba-bilistic and ensemble decisions making, and so informed use of metrics such as the CRPS is crucial. In this technical memorandum, we provide an overview of the CRPS. We highlight its growing im-portance, particularly in the context of machine learning, and then explain its relationship to various other metrics and scores commonly used in earth system forecasting, such as the Brier score and Mean Absolute Error. We then go on to apply the CRPS in the context of hydrological forecasting.
 
URL https://www.ecmwf.int/en/elibrary/81707-hydrologists-guide-crps
DOI 10.21957/16101872b5
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