October 1, 2019 SANDRP
Though South West Monsoon has not even started withdrawing from India, the IMD (India Meteorological Department) Press Release on Sept 30, 2019 has rather bureaucratically declared: “The 2019 southwest monsoon season comes to end with above normal seasonal (June to September) rainfall.” Why should the monsoon shop be closed even as the monsoon has refused to start withdrawing? May be the IMD was not happy that the SW Monsoon 2019 proved it so wrong, again!IMD had repeatedly, no less than three times (on April 15, May 31 and Aug 1) predicted that June-Sept Rainfall will be 96% of Long Period Average (LPA) rainfall of 880.6 mm, but the actual rainfall was 968.3 mm or 110% of LPA, way ahead of the error margins. The rainfall has been the highest since 1994, when it was 1001.6 mm. Monsoon rainfall has this year been higher than IMD forecast for the first time since 2013. The private forecaster, Skymet, was in fact even more wrong as it had predicted that rainfall at all India level will be 93% of LPA.
Even regional rainfall distribution has proved IMD forecasts wrong in most cases, except for North East and North West India where the actual rainfall was within error margin of the forecast rainfall. Similarly, IMD’s forecast for July rainfall, August Rainfall and Aug-Sept rainfall, were all proved wrong by the actual rainfall.
But let us come back to the core purpose of this article: Take stock of the June-Sept 2019 rainfall, all based on IMD figures. We hope to provide state wise rainfall figures in SW Monsoon 2019 in the next article and river basin wise rainfall in the third one.
State wise rainfall As we can see from map below, out of 36 states and Union Territories (UT) of India, one (Dadar and Nagar Haveli got 68% above LPA)) received Large Excess (more than 59% above LPA) rainfall, 11 received Excess (20-59% above LPA) rainfall, 20 received normal (Between 19% above to 19% below LPA) rainfall and four received deficit (20-59% below LPA) rainfall. The four deficit rainfall states were: Manipur (56% below normal), Haryana (42%), Delhi (35%) and Jammu & Kashmir (21%).
Out of 20 states that have normal rainfall, 13 have received below LPA rainfall and for nine of them the deficit is 10% or more: W Bengal, Jharkhand, Uttarakhand, Himachal Pradesh, Chandigarh, Assam, Arunachal Pradesh, Nagaland, Mizoram, all in North, East and NE India.
Among the 11 excess rainfall states, some states with high excess include: Madhya Pradesh (44% above LPA), Rajasthan (40%), Gujarat (43) and Andaman and Nicobar Islands (41%).
Some of the states with the highest rainfall included: Goa (3917.6 mm), Dadar-Nagar Haveli (3622.8 mm), Meghalaya (2431.8 mm) and Andaman & Nicobar (2331.3 mm). Some of the states with the lowest rainfall included: Haryana (255.2 mm), Delhi (378.1 mm), Tamil Nadu (401.6 mm), Punjab (444.3 mm) and Jammu & Kashmir (445.8 mm).
Sub Division wise rainfall IMD divides the country into 36 meteorological sub divisions and provides a map showing the rainfall in each sub division, along with normal rain and % departure from normal rains. As we can see from the map below, two sub divisions (Saurashtra and Kutch-66% above LPA & West Madhya Pradesh-61% above LPA) had large excess rain, ten sub divisions had Excess rain, 19 sub divisions had normal rain and five sub divisions had deficit rain.
All five deficit sub divisions are either from North India (Jammu & Kashmir, Haryana-Chandigarh-&-Delhi (42% below normal) and West Uttar Pradesh (27%)), East India (Gangetic W Bengal (20% below normal) or North East India (Nagaland-Manipur-Mizoram-Tripura or NMMT 22% below normal).
Among the ten regions with excess rainfall, three had rather high excess: Madhya Maharashtra (55%), Konkan & Goa (53%) and East Rajasthan (53%).
Among the 19 sub divisions with normal rainfall, six had deficit 10% or more: Jharkhand, Uttarakhand, Himachal Pradesh, Arunachal Pradesh, Assam & Meghalaya (12%) & the only one from peninsular India: Marathwada (12%). So even in this season where every one of the rest of the sub divisions in Peninsular and South India had excess rainfall, Marathwada still had 12% deficit rainfall.
Among the 36 sub divisions, four had above 2000 mm rainfall: Kerala & Mahe (2310.2 mm), Andaman & Nicobar Islands (2331.3 mm), Coastal Karnataka (3796.5 mm) and Konkan & Goa (4385.8 mm). Five regions have below 500 mm rainfall this monsoon: Haryana-Chandigarh-& Delhi (258.6 mm), West Rajasthan (315 mm), Tamil Nadu-Puducherry-&-Karaikal (401.9 mm), Jammu & Kashmir (445.8 mm) and Rayalseema (459.9 mm).
River Basin Wise Rainfall IMD also reports river basin wise rainfall, though the accuracy of the figures sometimes sounds more doubtful then rest of IMD figures. We will report about the river basin wise rainfall in greater detail in a separate blog, as we have been doing last two years, here we are just giving the map and couple of highlights.
Chambal basin is the only basin across India that has received large excess (74% above normal) rainfall during 2019 SW Monsoon in India. There are at least five basins that have received deficit rainfall: Chenab (-25%), Ravi (-30%), Upper Ganga (-22%), Upper Yamuna (-33%) & Middle Yamuna (-25%). Shockingly, IMD has no rainfall figures for Jhelum, Indus and Imphal-&-Others Basins.
CUMULATIVE RAINFALL BAR CHART – All India The bar chart below, also from IMD, provides the daily cumulative All India rainfall throughout the SW monsoon from June 1 to Sept 30, 2019, along with the normal cumulative rainfall for the respective dates. As we can see, the cumulative rainfall was below normal till around Aug 9, 2019, and starts becoming normal and above normal thereafter.
In Conclusion IMD could come up with the maps and figures of the SW Monsoon once the SW monsoon officially withdraws from India. IMD has forecast that the withdrawal is likely to start from Oct 10, and that will be a new record as the record so far is Oct 1. The monsoon is clearly breaking a lot of records this year. This is the new reality and we must prepared to deal with these new realities rather than just push it under the carpet of Climate Change, and say how difficult it is to forecast.
SANDRP ([email protected])
Surplus 2019 monsoon in India proves IMD and Skymet Wrong
Surplus 2019 monsoon in India proves IMD and Skymet wrong
October 1, 2019 SANDRP