Unusually heavy rain in parts of northwest India on 30 June 1981

Abstract

The unusually heavy rain which occurred in New Delhi and parts of Haryana and of the plains of west Uttar Pradesh on 30 June 1981 has been studied in this paper. Rohtak, Agra and New Delhi (Palam) recorded 30, 26and22cmofrain respectively during the 24hours ending at 0830 I.S.T. on 30 June 1981. New Delhi (Safdarjung) recorded 19 cm. The heavy rainfall has been associated with availability of moisture in abundance over and near these areas as deduced from the analysis of radiosonde ascents taken at New Delhi, Patiala, Gwalior, Jodhpur and Lucknow. The trigger for the vertical motion was provided by the low level convergence associated with the seasonal trough which was well-marked and whose axis on sea level chart passed through Amritsar, Delhi, Lucknow and Gaya on 29 June.