Exceptionally heavy rainfall over Uttarakhand during 15-18 June, 2013 - A case study

Abstract

Uttarakhand experienced exceptionally heavy rainfall, which caused floods and huge damage to life and property over the state during 15-18 June, 2013. Movement of a deep westerly trough between longitude 65.0° E to 70.0° E and a low pressure area over west Madhya Pradesh and adjoining east Rajasthan along with moisture incursion from Bay of Bengal as well from Arabian sea over western Himalayan region (WHR), more particularly over Uttarakhand have been examined. The moisture flux started rising from 180 gm/kg on 10 June to about 250 gm/kg on 15 June and about 500 gm/kg on 16 June. Outgoing longwave radiation (OLR) was about 190 w/m2 during 15 to 17 June and it rose to 220 w/m2 on 18 June. The precipitable water contents increased from about 23 gm/cm2 on 10 June to about 34 gm/cm2 on 16 June. Upper level divergence was more than 15×10-5s-1 and the lower level convergence 20×10-5s-1 during heavy rainfall period over the region. Relative humidity started increasing from 14 June onwards and become about 90% at 700 hPa and about 80% at 500 hPa on 16 June, 2013. Tropical rain measuring mission (TRMM) rainfall was of the order of 40-80 mm/day on 14 and 15 June and 120-160 mm/day on 16 June, 2013 over a large part of Uttarakhand.