Heavy rainfall events over Rajasthan and Madhya Pradesh during 1st week of August 2021: a meteorological case study

Abstract

During southwest Monsoon, heavy rainfall and flood events are usually observed in different parts of the country. Therefore, their documentation and systematic study is an important scientific work. This can help in the improvement of weather forecasting and also mitigation of associated natural disasters. The investigation of associated meteorological features is a matter of concern for operational forecasters. In this study, a case of persistent heavy rainfall events is considered that occurred during the first week of August 2021 over some parts of Rajasthan and Madhya Pradesh. Some of the stations from these regions received an all-time high 24-hour (RR24) cumulative precipitation in August 2021. Due to this event, flooding occurred and a huge loss of agricultural and horticultural crops occurred in some parts of Madhya Pradesh and adjoining areas. The present study attempts to understand the various meteorological features associated with this heavy rainfall event. Following meteorological features are found to be favourable in this weather activity; (i) Synoptically, there was a well-marked low-pressure area/ low-pressure areas over the region with the associated cyclonic circulation extending up to middle/upper tropospheric levels. (ii) Availability of continuous moisture supply at lower levels over the region. (iii) Favourable dynamical parameters like relative vorticity up to upper tropospheric levels, high values of low-level convergence, and upper-level divergence over the region. (iv) CAPE of the order of 1000-2000 J/Kg reported over Rajasthan and Madhya Pradesh mainly over northern parts remained which helped formation of intense convection. (v) In addition to CAPE, KI of the order of 35-40 were reported over Rajasthan and Madhya Pradesh with isolated patches of 40-45; LI of the order of -2 to -4 are reported over most parts of the country except for the order of -4 to -6 with isolated patches of the order of -8 to -10 and SWEAT Index in the range of 400-500 °C over northwest Madhya Pradesh & adjoining east Madhya Pradesh.