Use of DMI-Hirlam for Operational Dispersion Calculations

During the latest decades there has been a. rapid progress in the ability to forecast weather. This progress has been possible because of the development of advanced numerical weather-prediction (NWP) models running on the most powerful computers available. Especially, there has been progress in the capability to make numerical forecasts in the range from one day to about a week ahead in the Northern Hemisphere which is dominated by the travelling weather systems. On longer time scales, there has been some progress, but severe difficulties are met due to the intrinsic chaotic nature of the atmosphere.