Monsoon season officially ‘ends’ but rains continue; several new records set

Vibha Sharma
Tribune News Service
New Delhi, October 1

The four-month monsoon season that officially starts on June 1 ended on Monday. However, if the IMD’s forecast and the current weather conditions are any indication, the seasonal rains— the source of irrigation for two-third of the country’s farmlands— is not over yet.

The 2019 Southwest Monsoon is yet to complete its run for the year. The withdrawal of seasonal rains, which officially starts from the north-west region around September 1, is expected to begin around October 10, as per IMD.

In fact, this monsoon season will be recorded amongst the most unusual and uneven and one which has broken several past records.

The most delayed withdrawal in the past years was recorded on October 1, 1961 followed by September 30, 2007.

As per the IMD, the 2019 Southwest Monsoon season also ended with “above normal seasonal rains”. 

Quantitatively, the rainfall was 110% of its Long Period Average (LPA), which is 88 cm. However, the variation in the 36 meteorological subdivisions has been vast.

Two subdivisions received ‘large excess rains’, 10 received ‘excess’ rains and 19 subdivisions received ‘normal’ rainfall.

Five subdivisions received deficient rainfall all in the range of 20 per cent except one-the Haryana, Delhi and Chandigarh subdivision.

This particular subdivision in the north-west ended with a deficiency as high as 42 %. Together these five subdivisions account for about 15% of total area in the country.

On an average, about 20% of area of the country received deficient or scanty rainfall this season. And in spite of late monsoon onset and large deficient rainfall during the month of June, the seasonal rainfall ended in “above normal category” with 110% of its LPA and that is because of deluge in many parts like Bihar, Madhya Pradesh, Maharashtra, Kerala.

Records

*As per the IMD, rains during July, August and September were 105%, 115% and 152% of LPA, respectively.

• It is after 1994 (110% of LPA) that the country received as much rain —110 % of LPA in 2019. It is the highest season rainfall received by the country as a whole.  

*During 18 of the last 19 years (2001-2019), North-East India has received rains less than LPA with an exception of 2007 (110% of LPA).This indicates that the seasonal rainfall over North-East India is passing through a below normal epoch like it was during early 1950s to mid-1980s.

*After 1931, this is the first time, the seasonal rainfall is more than LPA even after the June rainfall deficiency was more than 30% of LPA.  

*After 1996 (119 % of LPA), this is the highest recorded August rainfall (115% of LPA).

*This is the second highest September rainfall (152 of LPA), after 1917 (165% of LPA).

*After 2010, this is the first time, rainfall during all the last three months (July to September) were above LPA.  

*The highest cumulative rainfall during August-September (130 %) has been recorded in 2019 after 1983 (142 %)

In spite of several global models indicating a strong possibility of continuation of an El Nino episode during the monsoon season and possibly a below normal monsoon, IMD had predicted a normal rainfall (96-104% of LPA) for the 2019 Southwest Monsoon season.

IMD’s quantitative forecast for the season rainfall issued in April and May was 96% of LPA with a model error of ± 5% and ± 4% of LPA respectively. While issuing the forecasts, based on IMD’s models, it was suggested that the El Nino episode will weaken further and a positive Indian Ocean Dipole (IOD) event will emerge in the Indian Ocean.