NEW DELHI, Jan 14 (Reuters) - Cloudy conditions due to unexpected weather led to the helicopter crash last month that killed the head of India"s armed forces, General Bipin Rawat, and 13 others, the government said in a statement on Friday. "The accident was a result of entry into clouds due to unexpected change in weather conditions in the valley," the government said, citing a preliminary investigation carried out by a Court of Inquiry set up by the country"s armed forces. Rawat was among the 14 people travelling in the Indian Air Force helicopter in December that burst into flames after ploughing into a hillside in the southern state of Tamil Nadu.