A low pressure area over the Northwest Bay of Bengal (BoB) crossed the coast last night. The weather system is now lying over coastal parts of North Odisha and Gangetic West Bengal and partly over sea. The system has a broad cyclonic circulation over this area, extending up to middle levels, tilting southward with height. Low pressure will move northwestward over the interiors of North Odisha and Jharkhand region. Also, it is going to meander over parts of Jharkhand, Chhattisgarh, Bihar and the neighbourhood for the next 3days or so. Accordingly, the southwest monsoon will remain active over this region during this week.
The northward shift of this system will take the monsoon trough along. Earlier, this trough, the main driver of monsoon rains had slid the eastern end far to the south for fairly long and with such a situation, there were not adequate rains over West Bengal, Bihar and Jharkhand for the last 3 days. This activity is likely to pick up for the complete region and last, at least till the weekend. To start with, decent rains will lash Odisha and West Bengal for the next 48 hours. Subsequently, the spread and intensity of rains will increase and also extend, to cover Jharkhand and Bihar. Heavy rains are likely over Bihar, particularly along the foothills, running across West Champaran, Sitamarhi, Madhepura, Supaul, Araria, Kishanganj and Purnea.
Peripherals of the weather system will also give moderate showers over Chhattisgarh, East Madhya Pradesh and East Uttar Pradesh. There is perpetual rainfall deficiency over these parts during this season and never recovered from the shortfall. As of today, the shortfall over Bihar and Jharkhand is in excess of 30% and West Bengal is close behind with 25% rainfall. This wet spell will arrest the further drop, if any and may marginally improve the state.
During the next 3-4 days, North Bihar and North Bengal have to watch out for inclement weather activity on account of the movement of the monsoon trough. Heavy thunderstorms may be accompanied by lightening storms and strong winds. The farming community and the labour class need to exercise caution, to prevent damage on account of lightning strikes which will be frequent during this period.