30 Years of Ensemble Forecasting and Symposium for Prof. Tim Palmer

During the 1970s, the “butterfly effect” or “chaos” was the dominant theme of predictability research, and the community was skeptical about the prospects for dynamical prediction beyond weather. I will give an overview of the evolution of the ideas that lead to the notion of predictability in the midst of chaos and established a scientific basis for dynamical seasonal prediction.

Ever...

During the 1980s the Met Office produced experimental monthly forecasts, provided to users on a regular basis. While medium-range dynamical predictions were used for days 1-5 ahead, forecasts for days 6-15 and 16-30 were based on statistical methods driven by observations. During this period, Tim and I developed a prototype system for dynamical monthly forecasts that could be run in real-time....

Research on ensemble predictions started at ECMWF in the mid 1980's, using a time-lagged approach to generate 30-day ensemble forecasts initialised from consecutive operational analyses produced every 6 hours. While early experiments showed some positive results, it soon became apparent that the lagged ensembles were under-dispersive in the medium-range, and research on alternative methods was...

One of the major advances in weather prediction of the past three decades has been the provision of accurate and reliable uncertainty estimations. This has been achieved by shifting from issuing a single to an ensemble of forecasts. Since the first implementation in 1992, the key questions that we had to address have been ‘what are the sources of forecast error?’, and ‘how are we going to...

Ensemble forecasts play an essential role in quantifying the uncertainty inherent in all weather forecasts. They give a direct assessment of the range of possible future weather scenarios. This provides forecast users with the necessary information to assess the risk of specific events that may affect their activity and to take appropriate decisions. It is important also to provide users with...

In the mid-eighties, the interaction of atmospheric low frequency variability between tropics and extra-tropics became a hot topic. Tim, anticipating its practical importance, promoted a series of experiments to quantify the influence of the tropical circulations on forecast of extratropical weather. Our results showed that the impact of the tropics was particularly important for the...

Solar and wind generation are obvious examples of where good weather forecasts are important, and so we will start there. As we go into a little detail about the influence of renewables on the supply/demand balance, it will become evident that the temporal and spatial coherence of ensembles are a good match to the largely instantaneous, and interconnected, nature of power systems. Renewables...

Near-term climate predictions exploit the predictability of the climate system arising both from the initial condition information and from external forcings resulting from changes in atmospheric composition, solar radiation, and land use. Predictions from one to several years in advance represent the natural extension of seasonal predictions, so they can be considered as initial-value...

"...one can prepare, one can strive, one can make a choice, but ultimately life is an elaborate game of providence and probability...."
(Daniel Silva, 2021)

During the last three decades, there have extraordinary advances in the field of weather prediction. At the forefront of these advances been the creation of ensemble systems using global models with models of ever increasing...

Acting before a disaster can help humanitarian organisations to reduce the impacts on lives and livelihoods, but sufficient lead-time is required to support this decision-making. In this talk I will discuss the use of ensemble forecasts within the Red Cross Red Crescent movement and beyond, highlighting examples of how earlier identification of extreme weather events enabled humanitarians to...

This talk will provide an overview on the ensemble forecasts as they are performed at ECMWF today. The talk will cover the latest developments towards the 9 km resolution  upgrade and provide a perspective on future developments towards km-scale simulations.