After running into stiff resistance over the atmospheric 'tri-junction' of Jammu & Kashmir, Punjab and Haryana, the monsoon is preparing to break through into Rajasthan, its last destination. The resistance, it appears, had been mounted by the comparatively higher pressure built up over the region following surplus pre-monsoon showers.
Surplus rain
Rain clouds can form and prosper only over land suitably warmed up by the summer sun. The heated up air expands, rises and cools to form clouds at much higher levels in the atmosphere. Once the cooling breaches a threshold, these clouds break down to fall as rain. But the entire process came to a standstill as the pre-monsoon rain over Rajasthan cooled the surface.
The cool air is dense and heavy, and does not allow the rising motion necessary to form clouds in the higher atmosphere. The monsoon had run into a similar bump over Madhya Pradesh as well.
But India Met Department (IMD) is of the view that things may be readying to change after a lull that has lasted for more than a week over North-West India and heated up the surface.
Favourable conditions
The ice will break with a current monsoon circulation over West Bihar gets amplified due to moisture incursion from the Bay of Bengal and travels to Central, West and North-West India in due course.
The IMD said that favourable conditions are developing for the monsoon to enter the rest of Jammu Division and Himachal Pradesh, more parts of Haryana and Punjab over the next three days.
A weather tracker featured by the US Climate Prediction Centre too had hinted from last week at the possibility of a rain-head moving across from East India to West India.
The IMD sees the system gathering intensity with its movement to the West and reaching the strength of a depression by the time it reaches Gujarat and adjoining Mumbai-Konkan by July 17.
Meanwhile, the lag over North-West India might cause monsoon to forfeit its lead that would have helped it cover the entire landscape ahead of the normal July 15 timeline.