Lightning research is usually focused on the most active months of the year, those corresponding to the summer season. These thunderstorms produce most of the lightning records during a year in the Basque Country, and they are recorded for further research. In this paper winter lightning is under study. After the dramatic descent in the number of strokes recorded with the end of the summer season, a number of winter thunderstorms crossed the territory. Two different episodes (one in November 7th and 8th, and a thunderstorm in November 30th) left evidence of lightning in the weather radar tower located at Kapildui Mountain. In this paper the research carried out from the first evidence of electrical activity in the tower to the final conclusions of being upward negative flashes initiated by the tower is presented.