Eastern states of Bihar, Jharkhand and Gangetic West Bengal continue to be stressed with below-normal rains, even as the monsoon crosses halfway mark. Bihar got some respite last week between 28th July and 03rdAug. The state received 88.2mm of rainfall against the normal of 68.4mm, an excess of 29%. This wet spell dragged the seasonal deficit from -42% to -33% now. However, Jharkhand and Gangetic West Bengal experienced a shortfall of -33% and -52% rainfall during the same period. As of 03rdAug 2022, Bihar, Jharkhand and Gangetic West Bengal have a seasonal deficiency of -33%, -48% and -47% respectively.
Monsoon trough and seasonal low pressure systems are the main drivers of rainfall for these states from June to September. Neither the monsoon trough is staying long enough over the region nor the monsoon systems are traversing across the states for adequate period. Sufficient number of systems formed over Bay of Bengal in July but they just looked the other way and sped across the central and western parts. Most parts of Maharashtra, West Madhya Pradesh, the whole of Gujarat and Rajasthan got drenched with intense and widespread rains at regular intervals. The eastern states did not find favor and got excluded from decent showers, more so when these were needed the most.
A pair of weather systems is expected to emerge over Bay of Bengal shortly. The 1st one forms around 05th/ 06thAug and the 2nd low pressure develops on 11th/ 12thAug. Both the systems once again will take the aerial route stretching across the central parts and travelling till far west to Gujarat and Rajasthan. The eastern end of monsoon trough will be pushed far to the south keeping safe margins from the eastern states. The peripheral of these weather systems may give scattered light showers over South Jharkhand and South Gangetic West Bengal, leaving the state of Bihar nearly dry.
July and August are the rainiest months for all the 3 states, with over 300 mm rainfall in each month. Scanty rains are likely over eastern parts and these will remain limited to southern half of Jharkhand and lower half of Gangetic West Bengal. State of Bihar will largely stay dry for one week. Even northern half of Gangetic West Bengal covering Malda, Murshidabad, Birbhum, Nadia, Dinajpur and Baharampur will hardly find any rains. Light to moderate rain and showers are expected over Ranchi, Jamshedpur, Gumla, Khunti, Singhbhum, Simdega, Kolkata, Midnapore, Jhargram, Hooghly, 24 Pargana, Diamond Harbour and Contai between 07th and 10thAugust.