Abstract 155

Abstract ID: 155

UK Hydrological Outlook: Operational river flow forecasting using spatially-distributed seasonal rainfall forecasts

Lead Author: Mark Rhodes-Smith
UK Centre for Ecology and Hydrology, United Kingdom

Keywords: Hydrological forecasting, River flows, Flood and drought risk, Forecasting methods, Uncertainty communication

Abstract: The UK Hydrological Outlook (https://hydoutuk.net/) is an operational hydrological forecast of river flows and groundwater levels for Great Britain, produced at the start of each month to cover the next one- and three-month periods. The Outlook provides actionable intelligence on regions with heightened flood or drought risk over seasonal timescales, complementing the short-term flood forecasting by other agencies. It comprises multiple hydrological forecasts ranging from statistical methods to the use of Met Office seasonal rainfall forecasts from GloSea5. Since 2012, these latter have comprised an ensemble of national-scale spatially-homogenous rainfall forecasts which were used as an input to hydrological models, but recent improvements have enabled the generation of spatially-distributed forecasts derived from the state of the North Atlantic Oscillation.
Here, these new forecasts are incorporated into a hydrological model used for the Outlook, and twenty-two years of hindcasts are evaluated to assess performance. Improved methods to communicate the probability distribution sampled by the forecast ensemble are presented to meet the needs of various end users. Our ongoing work will incorporate our developing understanding of model uncertainties to further refine the forecast distribution.

Vicky Bell (UKCEH)
Rosanna Lane (UKCEH)
Helen Davies (UKCEH)
Helen Baron (UKCEH)