New Delhi, Jan. 19 -- The severe cold spell that northwest India experienced from December 15 to December 30 was unprecedented, an analysis by India Meteorological Department (IMD) shows. The maximum temperature over northwest India in December was 17.5 degrees Celsius - the lowest since 1971. The average maximum temperature's departure from normal for December was also the lowest since 1971 at -3.2 degrees Celsius. The analysis was made based on data from Jammu and Kashmir, Himachal Pradesh, Punjab, Haryana, Delhi, Uttarakhand and Uttar Pradesh.p8...