Lok Sabha Question No. 2468 (UNSTARRED), answered on 2022-03-16
Subject: Predictions of Heavy Rains
Ministry: EARTH SCIENCES
Asked by: Maddila  Gurumoorthy, Kuruva Gorantla Madhav, Sanjeev Kumar Singari, Midhun Reddy, Adala Prabhakara Reddy

## GOVERNMENT OF INDIA MINISTRY OF EARTH SCIENCES LOKSABHA

## UNST ARRED QUESTION NO. 2468 TO BE ANSWERED ON WEDNESDAY, 16 TH MARC 2022

## PREDICTIONS OF HEAVY RAINS

2468. SHRI MADDILA GURUMOORTHY: SHRI KURUVA GORANTLA MADHAV: DR. SANJEEV KUMAR SINGARI: SHRI P.V. MIDHUN REDDY: SHRI ADALA PRABHAKARA REDDY:

Will the Minister of EARTH SCIENCES be pleased to state:

- whether India Meteorological Department(IMD) estimate of monsoo in Andhra Pradesh has been accurate during the current year and if so, the de,ails th reof; (a)
- whether the Government has identified the reasons for heavy rains, if 0, the details thereof; and . I (b)
- whether any scientific advances have been made in regard to making accurate predictions and if so, the details thereof? (c)

## ANSWER

THE MINISTER OF STATE (INDEPENDENT CHARGE) FOR MINISTRY OF SCIENCE AND TECHNOLOGY AND EARTH SCIENCES (DR. JITENDRA SINGH)

- Yes Sir. India Meteorological Department (IMD) issued forecast fo south west monsoon seasonal rainfall (l5t Stage) on 16th April 2021 (Figurcl la) d its update was given on 15tJune 2021 (Figure 1b). The observed rainfall dist~ibutio during 2021 Southwest monsoon season is given in Figure Ie. The sub-divisional istribution of Monsoon Seasonal Rainfall 2021 for the country is given in Figur, Id ad itionally. (a)

From the figures (Figure la and Figure Ib), it is found that the abdve .. monsoon seasonal rainfall was predicted for most parts of Andhra Pradesh.

From the observed rainfall distribution given in Figure Ie, it is found t at most parts of Andhra Pradesh received above normal rainfall during 2021 whfh is further ascertained by the sub-divisional monsoon seasonal rainfall distributionrap given in Figure 1d for the year 2021. As per this map, the percentage d~parture of seasonal rainfall of Andhra Pradesh against the normal is +20 which ~omesJunder above normal (excess) category.

- The heavy rains received over South Peninsula and adjacent Cenral In ia during the Southwest monsoon season 2021 was mainly associated wit~ passrge of Low Pressure Systems during the season. During the 2021 SW monspon Season, a total number of 13 Low Pressure Systems formed and majority of the sfstems formed over Bay of Bengal moved west-northwestwards causing intense ramfall ~ctivity over Central and Peninsular India. (b)

umber of Low pressure System (LPS) including Low (L), ' Well l' ~arked Low WML), Depression (D), Deep Depression (DD), Cyclonic Storm ( t:S) ar d number of PS days in monsoon 2021 are given below: N ( L

| Systems I Month   |   Cyclonic' storm'[ |   Deep Depression |   Depression | Well-mar ed low- pressu re area   |   Low- pressure area |
|-------------------|---------------------|-------------------|--------------|-----------------------------------|----------------------|
| June              |                   0 |                 0 |            0 | 0                                 |                    1 |
| July              |                   0 |                 0 |            0 | 1 I                               |                    2 |
| August            |                   0 |                 0 |            0 | 0                                 |                    2 |
| Sept              |                   1 |                 1 |            1 | 2                                 |                    1 |

- (c) MD regularly reviews the operational long range forecasting sy. tern t n improve it ... !hrough III house research activities & collaboration With vanoJs clll11[ate research institutions in the country. The operational statistical models are Jainly tmproved by implementing the latest state of the art statistical forecasting techniques and by using better predictors. Similarly, Ministry of Earth Sciences (MoES) ha~ launched National Monsoon Mission (NMM) with a vision to develop state-ot+the-a1 dynamical prediction system for the monsoon rainfall in different timel scaler.IMD used Monsoon Mission Climate Forecast System (MMCFS) mOrel fa preparing operational forecasts since 2018 monsoon season.

This year, IMD has implemented a new strategy for issuing morthly and seasonal operational forecasts for the southwest monsoon rainfall over the I country by modifying the existing two state forecasting strategy. The ne,. strat9gy uses the existing statistical forecasting system to generate these forecasts along W~ith a newly developed Multi-Model Ensemble (MME) forecasting system ~ased on coupled global climate models (CGCMs) from different global climate prediction nd research centers including IMD's Monsoon Mission CFS (MMCFS) mOdel.j I

IMD is effectively functioning in the country maintaining accurrte weather monitoring and forecasting of all the weather based natural disastJrs. During the past few years, IMD has been continuously improving weather predicti n serVicesin terms of accuracy, lead time and associated impact. I

For this purpose, IMD follows a seamless forecasting strategy. Th~ long-range forecasts (for the whole season) issued are being followed with ext nded range forecast issued on every Thursday with a validity period of four wFeks. 0 follow up the extended range forecast, IMD issues short to medium range forecast Jnd warnings at 36 meteorological sub-divisions levels daily four times valid uf to nclxt five days with an outlook for subsequent two days. The short to medium range torecast and warning at district and station level are issued with a validity of neit five rays and are updated twice a day. The short to medium range forecast is followed b very short range forecast of severe weather up to three hours (nowcast) for all the districts and 1089 cities and towns. These nowcasts are updated every three hou I s.

IMD started issuing Impact Based Forecast (IBF) recently which give de ils of what the weather will do rather than what the weather will be. It contains t~1 e details of impacts expected from the severe weather elements and guidelines to g neral public about do's and don'ts while getting exposed to severe weather. T1ese grodelines are finalised in collaboration with National Disaster Management Aut ority MA) and is already implemented successfully for cyclone, heat wave, thun ersto and heavy rainfall. Work is in progress to implement the same for other sever weat er elements.

The weather forecast accuracy is verified by IMD and errors a~d ski I scores are calculated seasonwise and annually. The heavy rainfall warning Ski~ for t e year 2021 and its comparison with the period 2002-20 are given in the Figure 2. Frof the figure, it is found that Probability of Detection (POD) for heavy rainfall aminE with 24 hr lead period is 74% in 2021, which has improved by 51% in year 2~21 as ompared to their skill between 2002-20. False Alarm Rate (FAR) and Missing : ate ( R) are 26% in 2021, which has improved by 21% & 53% respectively in year 2021 s compared to their skill between 2002-20.

Fig 1a. Probability forecast of tercile categories normal) for the seasonal rainfall over India during the 2021 southwest monsoon season (June-September). The figure illustrates the most likely categories as well as their probabilities. The hite shaded areas represent climatological probabilities.

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Fig 1b. Updated Probabilityforecast for the seasonal rainfall ovl'ndi during the 2021 southwest monsoon season (June - September). The figure 'llustra es the most likely categories as well as their probabilities.

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Fig Ic. Observed rainfall distribution during 2021Southwest lonso September) season expressed as grid point rainfall tercile categories. n (June to

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Fig Id.The sub-divisional distribution of Monsoon Seasonal Rainf 11202

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Fig. 2: Heavy rainfall warning skill during 2021(FAR (FJlse Alarm Rate), MR(Missing Rate), PoD (Probability of Detection) and CS1l (Critkal Success Index).IMD has high skill for heavy rainfall warning upto Day 5 as POD for Day 5 is more than 50%.

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