Pre monsoon activities have intensified over northeastern parts of the country particularly over Sikkim, Assam, Meghalaya and Arunachal Pradesh. Scattered light to moderate rains are going on over sub-Himalayan West Bengal, Nagaland, Manipur Mizoram and Tripura. Eastern parts of Bihar have also witnessed scattered light to moderate rain.
There are multiple factors responsible for the enhancement of Pre monsoon activities over these areas such as formation of a cyclonic circulation over Bangladesh and adjoining areas, a cyclonic circulation over Eastern parts of Uttar Pradesh and adjoining Bihar and Jharkhand at lower levels and moisture feed from the Bay of Bengal in the form of south westerly and southerly winds.
Average rainfall over Assam, Meghalaya and Arunachal Pradesh usually increases threefold from March to April. We expect light to moderate rain with a few heavy spells to continue over Northeast India during next one week. With the chances of formation of a low-pressure area over South Andaman Sea and adjoining South Central Bay of Bengal, rain activities may start diminishing over northeastern part of the country. However, scattered light rain with one or two motor dispels may continue.
Light rain with one or two moderate spells may also occur over sub-Himalayan West Bengal, parts of Northeast Bihar. Pre-monsoon activities may intensify once again over northeastern part of the country by April 13 or 14.