Probabilistic Ensemble Forecasts of Turbulence for Aviation

The Met Office is one of two World Area Forecast Centres (WAFC) producing forecasts of aviation hazards, including turbulence, for aircraft around the world. In order to demonstrate the skill of these forecasts an objective turbulence verification scheme using high-resolution automated aircraft observations was set up. This was initially to assess and improve the deterministic model output. The Met Office Global and Regional Ensemble Prediction System (MOGREPS) was made operational in 2008 following 3 years of trials. The global ensemble model from this, MOGREPS-G has been used to produce further improvements to turbulence forecasting by creating probabilistic products. The probabilistic and deterministic turbulence forecasts are assessed globally over one year and results are shown for the skill, reliability and economic value of the forecasts. The results are for individual turbulence indicators and a combined indicator formed of a weighted sum of the individual turbulence indicators. The relative skill of the forecasts of the combined indicator using different weightings of the individual indicators will be shown. Some initial results, calibrating this probabilistic output will also be presented.