BOLAM is a hydrostatic model running twice daily at the National Observatory of Athens (0000 and 1200 UTC cycles). Two domains are used: one covering Europe with 15 km horizontal grid increment and one covering Greece and neighbouring countries with 6.5 km horizontal grid increment. For the execution of the model, initial and boundary conditions data from the U.S-GFS global model are used, kindly provided by the U.S. Weather Service.