Yesterday was the rainiest day of this monsoon season so far. Pan India 24 hour rainfall from 8.30 am on 18th July to 8.30am on 19th July was 14.1 mm, about 48% higher than the average of 9.5 mm for the day. Daily averages are the highest during 2nd half of July and range between 9.5 mm to 10 mm per day. July also is the rainiest core monsoon month with normal rainfall of 285.3 mm.
First 10 days of July 2021 remained poor throughout and the seasonal deficiency rose to 8%. This is beside the fact that June delivered its fair share and ended with a surplus of 10%.
Weak phase of the monsoon in June end and July not only consumed this surplus but also became deficient. July had gone through a roller coaster ride with persistent below normal rainfall till 11th July leading to a deficiency of 8%. Marginal recovery thereafter bettered this figure to 5% by 15th July but again slipped to 8% in the next three days.
The rainiest day with 14.3 mm on 19th July dragged this shortfall to 6% by registering 48% excess rainfall in 24 hours. Monsoon is expected to keep pace and assume a speedy run in the remaining days of July. Rainfall is going to match the daily normal on most days and may exceed the target on half of the occasions.
Season per se is having a shortfall of 22 mm till today and July is still reeling with a deficit of 38 mm. Promising days ahead will substantially reduce this margin and July may end with below normal rains by about 3%, as predicted by Skymet in its seasonal forecast.
Mainly two low pressure areas along with the seasonal trough along the Indo Gangetic plains will carry the monsoon flag to the farthermost pickets of Rajasthan and Gujarat. A cyclonic circulation has already formed over the North Bay of Bengal and will turn in to a low pressure in the next 24-48 hours.
This will activate the monsoon surge along the West Coast and pour adequate rains over West Bengal, Odisha, Bihar, Jharkhand, Chhattisgarh, Uttar Pradesh, Madhya Pradesh and Parts of Maharashtra, Rajasthan and Gujarat. Next low pressure is expected to form around 26th July as the remnant of a weather system over Myanmar enter Bay of Bengal and intensify rapidly.
This fag end system of July will carry the potential to possibly strengthen in to a depression over Bangladesh and adjoining West Bengal on 27th or 28th July. Subsequently, the depression will travel across West Bengal, Odisha, Jharkhand and further on the central parts of the country. This system alongside will activate the western end of the monsoon trough to push the rains to Delhi, Punjab, Haryana, West Uttar Pradesh and Uttarakhand.
Overall the monsoon rains will gallop across most parts of the country, outside Tamil Nadu, South Coastal Andhra Pradesh, Rayalaseema and Parts of Telangana. Heavy rains with possibility of cloud burst can not be ruled out across the hilly states of Uttarakhand, Himachal Pradesh and foothills of Punjab and Haryana on 25th and 26th July.
Localized flooding due to incessant rains under the influence of depression is quite likely over West Bengal, Jharkhand and Chhattisgarh between 28th and 31st July. Inclement weather conditions with strong lightening strikes necessitates utmost caution to safeguard life and assets.