Thiruvananthapuram, Jan. 21 The mercury has fallen by 3 to 4 deg Celsius over northwest and adjoining central India during the 24 hours ending Tuesday morning on the trail of a prevailing western disturbance. Further fall by another 2 deg Celsius is likely over the next two days, India Meteorological Department (IMD) said in its outlook.
While not entirely ruling out fog, it said strong surface winds would prevent ‘very dense fog’ from welling up over the plains during this period.
FRESH SYSTEM
They would have to contend with a fresh and moderately strong western disturbance featuring a likely embedded cyclonic circulation. The system may start impacting the region from Thursday onwards.
According to interpretation of numerical weather prediction models, concentrated weather activity will be witnessed around Saturday and Sunday when the system starts affecting the plains as well.
Fairly widespread rain or snow has been forecast over the western Himalayan region and isolated to scattered rain or thundershowers for the plains. Isolated rain or thundershowers are likely over Assam, Meghalaya and Arunachal Pradesh.
LIKELY GAINS
All-India area-weighted rainfall that showed a deficit of 63 per cent until January 14 when records were updated last is expected to have made some gains in Rajasthan, Punjab, Haryana and west Uttar Pradesh during the ongoing week.
The position is set to improve further with the expected arrival of the fresh system that is deemed to be deep enough to trigger rains and wet the farm lands in the north and the northwest.
But forecasters would not confirm if this would mark a decisive trend away from the cold and dry climes associated with a building La Nina in the equatorial east Pacific.
A La Nina, which causes seawaters to cool down and suppress rainfall along this stretch of the Pacific, is also known to dampen western disturbance activity over southwest Asia and contiguous northwest India.
But this conventional wisdom is being made to stand on its head if the aggressive westerly activity witnessed over the past week or so over the northwest is any indication.