As against earlier predictions, southwest monsoon is unlikely to set in over the national capital Delhi anytime soon. The likely monsoon onset date of 15th June for Delhi as assessed before will possibly shift around its normal date of 27th June or later. Speeding monsoon current reaching eastern states and some northern parts well ahead of schedule appears to be stalled temporarily. Onset over Delhi seems to be deferred, possibly for more than a week. Environmental conditions need realignment to fulfill essential changes with the arrival of monsoon currents.
The normal date of arrival over Delhi was 29th June till 2019. Onset and withdrawal dates of monsoon across India got revised based on the average dates of southwest monsoon arrival between 1961-2019. As per the new date, the normal monsoon arrival date to Delhi has been changed from June 29 to June 27, 2 days earlier than the previous schedule. Last year, the monsoon over Delhi arrived on 25th June, 2 days ahead of schedule, and withdrew on 30th Sep, much later than the normal date. A year prior, in 2019, the monsoon was delayed by one week and arrived on 05th July. Veering of +/- 5 days from the normal date falls within the standard deviation limits and is not considered crucial for the season as such.
Earlier predictions were largely driven by the emergence of low-pressure area over the Bay of Bengal on 11th June and its subsequent movement over Odisha, West Bengal, and neighborhood. This weather system is presently marked over northern parts of Jharkhand and the adjoining region. It is a very slow-moving system and may shift northwest in the next 24 hours. This low pressure has resulted in fairly widespread heavy rains over eastern states and also initiated change in the wind pattern across the Indo Gangetic plains. Because of its limited and sluggish movement, the weather activity will remain confined up to East Uttar Pradesh. In addition, the westerly winds in the medium level have been rather strong and expansive over North India. This pattern will restrict the advance of monsoon easterly winds beyond East Uttar Pradesh.
A western disturbance moving across northern parts has induced a cyclonic circulation over North Rajasthan and Punjab. This is likely to affect the weather over Punjab, Haryana, and Delhi in the next 2 days. Light to moderate rain and thundershowers are likely over Delhi and the neighborhood during this period. These pre-monsoon showers will mostly be witnessed during the evening and night. Lightning and thunderstorm accompanied with strong wind are expected over some areas on 15th and 16th June.