The four month long Monsoon season over the Indian region spanning from June to September, with a Long Period Average (LPA) of 89 cm of rain for this period, is conceived as a complex phenomenon.
Southwest Monsoon, after ushering in made a sluggish start with subdued activity in the initial phase and made a very slow advancement. After poor Monsoon rains in June, July too commenced with a 43% deficit – highest for the season - and remained so till 12th July. The month ended with a cumulative deficiency of 22% while at present rain deficit stands at 11%.
July and August are generally the active Monsoon months for the entire country. June is the onset month which witnesses an outburst of rain while, September is the withdrawal month, receiving more of sporadic rain.
Withdrawal is generally not attempted before 1st of September and commences from extreme west Rajasthan. As Southwest Monsoon approaches the withdrawal phase from a particular region, certain conditions become prevalent- change of wind pattern, reduction in cloud cover, decrease in humidity, cessation of rain and temporary rising tendency of temperatures.
North India
The present Monsoon system over Central India, unlike the previous one, took a north/northeastward turn from Gujarat and south Rajasthan. The system, after bringing good showers over Odisha, Chhattisgarh, Madhya Pradesh, Gujarat and south Rajasthan, re-curved to bring rain over northwest Madhya Pradesh and adjoining Uttar Pradesh.
The track of the system will dictate the withdrawal of Monsoon and cessation of rain from Northwest India. In the months of October and November, North India will mostly witness clear sky with least amounts of rainfall. Only the Western Disturbance could bring some rain, if at all.
According to latest weather update by Skymet Meteorology Division in India, this year, Southwest Monsoon is likely to withdraw from west Rajasthan anytime in the coming week.
Central India
In 2013, withdrawal of Southwest Monsoon was delayed from Central India as well. This time, Monsoon may withdraw in quick succession from Central region after bidding farewell from Northern parts.
East and Northeast India
This part of the country receives rain for the entire month of September and at least for the first 10 days of October. The normal date for the withdrawal of Monsoon from East and Northeast is 10th of October.
South India
Southern parts of the country enjoy the complete four month duration of Monsoon. The retreat of Southwest Monsoon coincides with the onset of Northeast Monsoon. The wind pattern will change from south westerly to north easterly. Therefore, Tamil Nadu and adjoining areas of coastal Andhra Pradesh will witness the rainiest period during the retreat of Monsoon.
Every year, some features of onset and withdrawal of Southwest Monsoon remains inexplicable and leaves behind a lot of questions unanswered. In fact, no two patterns of onset and withdrawal are similar. Last year withdrawal began quite late around 18th September from west Rajasthan, against the normal date of 1st September. Monsoon generally bids farewell from Delhi/NCR and other northern plains by 3rd week of September but was delayed till about 16th October.
