Whilst arriving at take off 2 gliders were already flying across from Lastra, and the day initially looked very good with Cu´s near to 4000m and convergence setting up in the Ambles valley.  The forecast wind was a little strong and over the back, so there was some doubt as to whether it would come on the hill at Peña Negra.  However, conditions were acceptable, if not a little bit turbulent close in, and most climbed out.   In a short period of time the nice looking clouds in the Ambles valley became Congestus monsters, so we decided to stay in the Valley near Piedrahita, Landing quite early to avoid the stronger conditions of the later afternoon.