Towards Understanding the weekly rainfall variability over India in June 2022

The rainfall over India in June 2022 was characterised by pronounced variability on weekly scale, along with the uneven spatial distribution from week to week. The country experienced the deficient rainfall in the first (-42%) and second (-24%) week, followed by excess rainfall (+ 44%) in the third week and again deficient rainfall (-30%) in the fourth week of June 2022 (http://imdpune.gov.in/). This weekly rainfall variation is found to be influenced by (i) anomalous large-scale circulation modified by the intensity and location of Western Pacific subtropical high (ii)subtropical upper tropospheric Asian jet over north India.This study further analyses the large excess rainfall over northwest India in the third week of June 2022. The background active phase of Indian monsoon and the southward penetrated upper tropospheric midlatitude trough of Rossby wave located over northwest India, interacted with each other, and reinforced the prevailing active monsoon condition over the region. This facilitated the excess rainfall over northwest India. An analysis of the observed datasets aimed at diagnosing the factors which could have led to the distinct weekly variability in June 2022 is presented in this paper. This study further elucidates the causes that lead to the large excess rainfall over northwest India in the third week of June 2022.