According to India Meteorological Department (IMD), during the just concluded Post Monsoon Rainfall for 2022, that included rainfall during Oct-Dec 2022 months, India received 144.1 mm rainfall, 19% above normal (177.7 mm rainfall, 43.54% above normal in Post Monsoon 2021[i]) rainfall of 121 mm. In the same period in 2020, India received 124.6 mm rainfall, 0.64% above the normal rainfall. As per IMD[ii] definition, the rainfall was in Normal category.
This three-month period from Oct 1, to Dec 31 includes the North East Monsoon that mainly affects parts of South India including Tamil Nadu, Puducherry, Rayalseema, parts of Karnataka and Kerala. However, since the South West Monsoon had not yet withdrawn from the country by Sept 30, a significant proportion of the rainfall in October was contribution of the SW monsoon. This was similar situation in 2019, 2020[iii] and 2021.
The period also includes the rainfall that most of North India gets from western disturbances, but that contribution has been very low so far this year. La Nina has also made some contribution in increasing the rainfall significantly above normal, which was also the case in 2021, but not in 2020.
In Post Monsoon season of 2019, India received 160 mm rainfall[iv] in this season, 29% above normal, when 2019 was not a La Nina year.
Monthly rainfall The distribution of rainfall for the three months of Post Monsoon 2022 season as per IMD is as follows. The rainfall is above normal only in October 2022, it is below normal in November and December 2022. There is no evident impact of La Nina here.
October 2022 has been the rainiest month since 2013, which in turn was the wettest since 1957. Oct 1917 was the wettest at 161.3 mm, since 1901 when records started to be kept.
October 2022 rainfall was 110.8mm rainfall against the normal of 75.4mm, an excess of huge 47%. Northwest India had the highest surplus at 198%, followed by Central India-64%. Uttar Pradesh, which otherwise was the driest during the southwest monsoon 2022, had the highest surplus at 575% in West Uttar Pradesh.[v]
|Months||Actual rainfall, mm||Normal rainfall, mm||% departure|
|Post Monsoon 2022||144.1||121||19|
Major unknown One major unknown, here is that it is not clear if IMD’s these reported figures include the contribution from snowfall and if so, what is the contribution of snowfall. It is not even known looking at the IMD website if IMD even monitors the snowfall figures and if so, what are they. We cannot find any reporting of the snowfall figures in any case. This is worrying since snowfall is expected to make a significant contribution during winter months and we seem to be in total dark as to what is the quantum of snowfall in different districts, states, in different months & years.
ALL INDIA: State wise rainfall Eight States and Union Territories (UTs) had Large Excess Rainfall (more than 60% above Long Period Average or LPA), 5 had Excess (20-59% above LPA), 14 had normal (19% below to 19% above normal) and 9 states and UTs had Deficit Rainfall (20 to 59% below normal) during Oct Dec 2022 period in India. Here LPA is Long period average, taken as average of the rainfall during 1971-2020. Punjab had the highest deficit at 54%. Pondicherry had the highest rainfall at 662 mm, way above the 2nd highest rainfall in Kerala at 476.1 mm. UP had the highest surplus % at 291%.
Sub-Division wise rainfall Among IMD’s 36 sub divisions, 6 received Large Excess, 10 received Excess, 14 received Normal, 4 received Deficit rainfall and 2 (Saurashtra-Kutch and W Rajasthan) had large deficit. Like in 2020 and 2021, Andaman and Nicobar Islands received the highest divisional rainfall at 666.9 mm.
River basin wise rainfall The media generally ignores this, but IMD also reports river basin wise rainfall, which is actually the most important way to report rainfall. But this year too IMD unfortunately has done a rather callous job of it. During Post Monsoon 2022 season, IMD reports ZERO rainfall in several basins: Tons, Vaippar-Pamba, Kynchiang, Imphal & Others, Barak and one more basin. This is clearly an impossibility. For two river basins (Jhelum and Upper Indus) IMD had no rainfall data (like was the case in 2019, 2020 and 2021)!
STATE WISE DISTRICT WISE RAINFALL: NORTH ZONE: Jammu and Kashmir
EAST ZONE: Uttar Pradesh
NORTH EAST ZONE: Assam
SOUTH ZONE: Andhra Pradesh
WEST ZONE: Maharashtra
[ii] India Meteorological Department (IMD) divides a water year (June 1 to May 31) into four seasons: Monsoon: (June 1 to Sept 30), Post monsoon (Oct 1 to Dec 31), Winter (Jan 1 to Feb 28/9) and Pre Monsoon (March 1 to May 31). For rainfall during all these seasons, IMD’s hydro-meteorological website provides a lot of data on daily basis, including daily district wise, state-wise, sub division wise and river wise rainfall maps among many other weekly, monthly and seasonal products. However, one problem with it is that none of this information is achieved. So if you missed seeing or downloading available data on any date, there is no way to look at it even next day. This is even true of the seasonal rainfall maps, unfortunately.