Skillful Seasonal Forecasts of Winter Disruption to the U.K. Transport System

The impacts of winter weather on transport networks have been highlighted by various high-profile disruptions to road, rail, and air transport in the United Kingdom during recent winters. Recent advances in the predictability of the winter North Atlantic Oscillation (NAO) at seasonal time scales, using the Met Office Global Seasonal forecasting system, version 5 (GloSea5), present a timely opportunity for assessing the long-range predictability of a variety of winter-weather impacts on transport. This study examines the relationships between the observed and forecast NAO and a variety of U.K. winter impacts on transport in the road, rail, and aviation sectors. The results of this preliminary study show statistically significant relationships between both observed and forecast NAO index and quantities such as road-accident numbers in certain weather conditions, weather-related delays to flights leaving London Heathrow Airport, and weather-related incidents on the railway network. This supports the feasibility of the onward goal of this work, which is to investigate prototype seasonal forecasts of the relative risk of occurrence of particular impacts in a given winter for the United Kingdom, at lead times of 1-3 months. In addition, subject to the availability of relevant impacts data, there is scope for further work to make similar assessments for other parts of Europe and North America where the NAO has a strong effect on winter climate.