INDIA METEOROLOGICAL DEPARTMENT (MINISTRY OF EARTH SCIENCES)

SOUTHWEST MONSOON-2013 END OF SEASON REPORT For the state of

Compiled By Dr. O.P. Singh, Scientist-F S.S. Singh, Scientist-F R.N. Kumawat, S.A. Ashok Kumar Sharma, S.A.

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HIGHLIGHTS For the country as a whole, the rainfall for the season (June-September) was 106% of its long period average (LPA). However, for North West this figure came out to 129% and 127% for the state of Rajasthan. Seasonal rainfall was 127% of its LPA over East Rajasthan and 128% of its LPA over West Rajasthan. Southwest Monsoon current advanced over the Andaman Sea 3 days earlier than its normal date of 20th May and set in over Kerala on its normal date of 1st June. The southwest Monsoon set over South Eastern parts of the state on 13th June, about 2 days early. It progressed further very rapidly and covered the entire state by 16th June, about 1 month earlier than its normal date of 15th July. The withdrawal of Monsoon from west Rajasthan commenced on 9th September compared to its normal date of 1st September. After 19th, further withdrawal of southwest Monsoon was stalled for about one month with the successive formation of two low pressure areas and their westward movement across the central parts of the country. The Monsoon withdrew from the whole state on 17th October, 2013, delay of about 22 days from the LPA. Monthly rainfall over the state was 138% of LPA in June, 127% of LPA in July, 133% of LPA in August and 104% of LPA in September. Out of 33 districts, 20 districts received excess rainfall during the season; 13 districts were normal and no district was either deficit or scanty. On micro level, out of 245 tehsils - 128 tehsils received excess seasonal rainfall; 94 tehsils normal; 23 tehsils deficit and no tehsil received scanty rainfall. About 90% area of the state received excess or normal rainfall during the whole season. Throughout the Monsoon season rainfall distribution over the state was very good on both temporal and spatial scale.

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1. Onset of southwest Monsoon – 2013

Associated with the formation of Cyclonic Storm Mahasen (10th - 16th May) over southeast Bay of Bengal, low level crossed equatorial Monsoon flow, strengthened over south Andaman Sea and adjoining south Bay of Bengal. This subsequently resulted in the advance of southwest Monsoon over Andaman Sea and some parts of southeast Bay of Bengal on 17th May i.e. 3 days before the normal date of 20th May. Cross equatorial flow over the Arabian Sea remained strong since the advance of southwest Monsoon over the Andaman Sea.

The southwest Monsoon set in over Kerala on 1st June, on its normal date. The same day, Monsoon advanced over entire south Arabian Sea, Maldives-Comorin area, Lakshadweep, some parts of central Arabian Sea, entire Kerala, some parts of Coastal & South Interior Karnataka and most parts of Tamil Nadu. Convectively active phase of the Madden - Julian Oscillation (MJO) and the associated systematic northward propagation of the east-west shear zone at the mid-tropospheric levels during the subsequent period helped faster advance of Monsoon and increased rainfall activity over the country.

The pace of advance of southwest Monsoon this year had been the fastest during the period 1941-2013. Since the onset took place over Kerala on 1st June, it rapidly covered the south peninsula and northeast India by 9th June and central, eastern parts by 12th June. It advanced further over some parts of SE Rajasthan on 13th June i.e. two days earlier than the normal date of 15th June. Presence of low pressure area over east Rajasthan & neighborhood superposed with a trough in the mid & upper tropospheric westerlies provided conditions conducive for the large scale convection and wide spread Monsoon rains over northwest India during next 3 days . This helped Monsoon to advance further over the entire state by 16th June, about a month earlier than its normal date of 15th July. On the same day Monsoon covered the whole country also. Fig.1 shows the isochrones of advance of Monsoon 2013.

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Fig.1 Progress of the southwest Monsoon – 2013

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Fig.2 Track of the Monsoon depressions

Fig.3 Tehsil wise rainfall distribution over Rajasthan Monsoon 2013

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2. Chief synoptic features

Strong cross equatorial flow prevailed during June and July. It gradually weakened during the latter half of the season. The axis of Monsoon trough remained in its near normal position and extended up to lower tropospheric levels without its characteristic southward tilt with height during most parts of the season. The seasonal ‘heat low’ weakened from the beginning of September. Subsequently, the axis of Monsoon trough also weakened and thereby became less delineated at mean sea level since 4th September. Though no typical break situation developed during the season, the rainfall pattern from the end of August to the first week of September resembled break like, as a consequence to the overall weakening of the Monsoon circulation. During the season, only 2 Monsoon depressions were formed against a normal of 6 depressions per season. However, 16 Monsoon low pressure areas were formed against a normal of 6 low pressure areas per season. The tracks of the 2 Monsoon depressions are given in Fig.2. One depression formed over the Bay of Bengal in the month of July and another formed over land in August. During the last about 30 years, there were two years (1984 and 1996) when 18 low pressure areas had formed in the Monsoon season. During each of both these years, 3 low pressure areas had intensified into depressions. Out of the sixteen low pressure areas formed during this season, 12 formed over the Bay of Bengal, 3 formed over land and one formed over the Arabian Sea. The month wise break up is 3 in June, 4 in July, 5 in August and 4 in September. The first low pressure area (4th -5th June) formed over the Arabian Sea under the influence of cyclonic circulation embedded in the shear zone during the onset phase. Though it was short lived. The formation of this low pressure area stalled the advance of the Monsoon over the Arabian Sea for 3 days (5th -7th June). However, the second low pressure area which formed over the Bay of Bengal moved west-north-west wards during 12th – 17th June up to Rajasthan and Haryana and its interaction with a trough in the mid & upper tropospheric westerlies helped the Monsoon to cover the entire country. During July one low pressure area (10th -13th July) formed over land and 3 low pressure areas (15th - 17th July, 19th - 25th July, 25th - 29th July) formed over the Bay of Bengal. All these 4 low pressure areas and one

6 depression (30th - 31st July) that formed over the Bay of Bengal moved north-west ward along the Monsoon trough and helped to maintain the Monsoon activity over the region. The cyclogenesis during the second half of the season had a major contribution from the remnant vortices from the east. A land depression formed during 20th - 22nd August over Gangetic West Bengal and adjoining northwest Bay of Bengal dissipated over east . The five low pressure areas that formed in the month of August were mostly of short duration. Two dissipated in-situ and were of 1 day duration, two moved up to east Uttar Pradesh and adjoining areas and the low pressure area during 9th -11th August dissipated over west Uttar Pradesh and adjoining areas of east Rajasthan. Monsoon activity in general remained weak over areas outside central and east India. During the first fortnight of the September, rainfall decreased considerably over the state. With the formation of a low pressure area over northwest Bay of Bengal on 19th September and its westward movement across the central parts of the country, the Monsoon activity revived. Even after the dissipation of the low pressure area on 23rd, the remnant of the system as an upper air cyclonic circulation remained quasi-stationary over State. Under the influence of this cyclonic circulation, another low pressure area formed over Kutch & neighborhood on 27th September and became less marked on 30th. The last low pressure area of the season formed over northwest Bay of Bengal and adjoining coastal areas of West Bengal and Odisha on 28th evening and persisted there till the last day of the season.

3. Flood situations

Incessant rainfall associated with the Monsoon low pressure systems and active Monsoon conditions in the presence of strong cross equatorial flow and deep Monsoon trough, often caused flood situations over Eastern parts (, , Kota and divisions ) of the state during the season. Towards the end of the season, Gujarat and adjoining areas of south Rajasthan experienced extremely heavy rainfall and flood situation due to the revival of the Monsoon activity associated with a cyclonic circulation that remained quasi-stationary for few days over Gujarat and neighboring areas.

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4. Withdrawal of south west Monsoon

The weather over the western parts of Rajasthan remained mainly dry for more than a fortnight (from 27th August). A change over in the lower tropospheric circulation pattern over the region from cyclonic to anti cyclonic during 8th - 9th September resulted in the withdrawal of southwest Monsoon from the region. Hence the withdrawal of southwest Monsoon commenced from 9th September and the withdrawal line passed through Ganganagar, and Barmer during 9th - 18th September. The Southwest Monsoon withdrew from some more parts of Rajasthan on 19th and the withdrawal line passed through Kalpa, Hissar, and Naliya. However, an almost complete revival in the Monsoon activity occurred from the 3rd week of September. With the successive formation of two low pressure areas and their westward movement across the central parts of the country caused the east-west trough to remain active contributing to above normal rainfall during this period over the state. This development stalled the further withdrawal of southwest Monsoon for about one month and finally the Monsoon could withdraw from the state on 17th October 2013 only. Fig.4 shows the isochrones of withdrawal of Monsoon.

Fig. 4 Isochrones of withdrawal of southwest Monsoon – 2013

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5. Rainfall distribution

The rainfall during Monsoon season (June to September) for the State as a whole and its two meteorological sub divisions are as follows:

Actual rainfall Long period average Departure from Region / Area ( mm) (LPA) mm normal (%) Rajasthan 531.8 418.7 +27 East Rajasthan 778.6 615.1 +27 West Rajasthan 335.8 262.7 +28

The seasonal rainfall over Rajasthan was 127%, East Rajasthan 127% and West Rajasthan 128% of its LPA respectively. The rainfall distribution was almost uniform over the State. All 33 districts received excess to normal rainfall of the season. A more micro distribution shown in Fig.3 shows that out of 245 Tehsils in the State, 128(52%) tehsils witnessed excess; 94(38%) normal; 23(10%) deficit and no tehsil witnessed scanty rainfall. Monthly distribution over the state and its two meteorological subdivisions is given below.

Rajasthan

Months Actual rainfall (mm.) Normal rainfall (mm.) % dep. from normal June 60.9 44.1 +38 July 199.3 156.8 +27 August 200.1 150.9 +33 September 69.6 66.9 +4

East Rajasthan Months Actual rainfall (mm.) Normal rainfall (mm.) % dep. from normal June 90.1 62.2 +45 July 318.5 225.0 +42 August 278.1 228.4 +22 September 88.2 99.5 -11

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West Rajasthan

Months Actual rainfall (mm.) Normal rainfall (mm.) % dep. from normal June 37.6 29.8 +26 July 104.6 102.6 +2 August 138.2 89.3 +55 September 54.8 41.1 +33

From the above tables it is observed that the monthly rainfall over the state during June , July and August was excess by 38%, 27% and 33% respectively from the LPA. While during September it was normal by 4% of LPA. The amount of rainfall ( in terms of % departure from LPA ) was more over East Rajasthan as compared to West Rajasthan during both June and July months. While during August and September, the trend reversed and the monthly rainfall was less over East Rajasthan as compared to West Rajasthan. During August the corresponding figures were +22% and +55% and during September - 11% and +33% over East and West Rajasthan respectively.

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District wise seasonal rainfall distribution

Sr. Monsoon rainfall in mm No. State/Districts (June-September) Year- 2013 Actual(mm) Normal(mm) %Departure Rajasthan 531.8 418.7 27 Met. Sub divisions East Rajasthan 1 AJMER 533.6 429.6 24 2 594.6 555.3 7 3 983.4 831.8 18 4 BARAN 1448.5 792.2 83 5 BHARATPUR 505.2 557.6 -9 6 655.9 580.9 13 7 865.8 655.9 32 8 914.7 709.7 29 9 759 612.1 24 10 827.5 650 27 11 868.1 637.8 36 12 JAIPUR 592.8 524.6 13 13 1355.5 855.1 59 14 409.2 410 -1 15 784.4 637.4 23 16 KOTA 1112.4 746.3 49 17 PRATAPGARH 1184.8 845.8 40 18 647.1 506 28 19 893.3 664 35 20 445.3 402.5 11 21 852.8 868.6 -2 22 TONK 763 566 35 23 UDAIPUR 704.7 591.3 19 East Rajasthan 778.6 615.1 27 West Rajasthan 24 BARMER 360.8 243.4 48 25 BIKANER 240.7 228.7 5 26 CHURU 376.6 313.7 20 27 292.3 252.5 16 28 200.4 158.4 26 29 540.4 394.2 37 30 JODHPUR 439.8 274.5 60 31 445.8 348.5 28 32 PALI 501.9 446.7 12 33 167 201.4 -17 West Rajasthan 335.8 262.7 28

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The cumulative seasonal rainfall for the State as a whole was +127% of its LPA and it was 127% and 128% of LPA over East and West Rajasthan respectively. Out of 33 districts, the seasonal rainfall was excess in 20 districts and normal in 13 districts . No district was either deficit or scanty category. got the least seasonal rainfall (83%) and , the highest seasonal rainfall (183%) of LPA.

5.1 Weekly and cumulative rainfall distribution

Weekly and cumulative rainfall distribution over the two Meteorological sub divisions of the state is shown in the following charts.

Fig.5 Week to week total rainfall over East Rajasthan - Monsoon 2013

Fig. 6 Cummulative weekly rainfall over East Rajasthan – Monsoon 2013

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Practically, on weekly basis the rainfall over East Rajasthan was insignificant during the weeks ending on 13th June, 4th, 11th and 18th September 2013 . A good amount (101 mm and 104 mm) was observed during the week ending on 31st July and 14th August 2013 respectively. The rainfall picked up considerably during 2nd week of July and lasted up to 3rd week of August. During the last two weeks of September, rainfall picked up considerably over East Rajasthan after a lull period of about three weeks.

Fig.7 Week to week total rainfall over West Rajasthan - Monsoon 2013

Fig.8 Cumulative weekly rainfall over West Rajasthan - Monsoon 2013

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Practically , on weekly basis the rainfall was insignificant ( less than 15 mm) during four weeks up to 2nd week of July and 4 weeks in September up to 25th September over West Rajasthan. The rainfall picked up over this met. Sub division also from 3rd week of July and lasted up to 3rd week of August. The highest (61.3 mm) rainfall was observed during the week, ending on 21st August 2013. With revival of Monsoon after middle of September, last two weeks of September also observed good rainfall activities over SW parts of the state. 48.6 mm of rainfall was recorded over West Rajasthan during the week ending on 30th September 2013.

5.2 District wise monthly, seasonal and daily rainfall distribution

Fig. 9 District wise montly rainfall distribution over Rajasthan - Fig.10 District wise montly rainfall distribution over Rajasthan - June 2013 July 2013

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Fig.11 District wise montly rainfall distribution over Fig. 12 District wise montly rainfall distribution over Rajasthan - August 2013 Rajasthan - September 2013

During June out of 33 districts, 21 districts received excess rainfall, 7 districts normal and rest 5 districts were scanty ; During July , a large area of the state got either excess or normal rainfall ( 17 districts excess ,14 districts normal and 2 districts deficit ). The situation persisted in the month of August also (20 districts excess, 12 districts normal and 1 district deficit). In September, about half area of the state received either excess or normal rainfall and the rest half got either deficit or scanty rainfall (11 districts excess, 5 districts normal, 10 districts deficit and 7 districts scanty) During the whole Monsoon season most of the area received excess rainfall. Out of 33 districts, 20 districts received excess and 13 districts normal rainfall. No district was deficit or scanty.

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Fig.13 District wise seasonal rainfall distribution over Fig.14 State wise seasonal rainfall distribution over India Rajasthan (June - September ) 2013 (June- September) 2013

Fig.15 District wise daily spatial rainfall distribution - Monsoon 2013

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Fairly widespread to wide spread rainfall occurred on 25 days (minimum) to 59 days (maximum) over different districts in East Rajasthan during the whole monsoon season . Pratapgargh district got widespread rainfall on 50 days (highest) during the whole season. Churu, Bikaner, Hanumangarh, Jaisalmer and Sriganganagar districts of West Rajasthan received widespread rainfall 2 to 3 days only during the whole season.

Fig. 16 District wise daily heavy rainfall distribution - Monsoon 2013

Heavy to very heavy rainfall occurred at isolated to most places in all districts of the state on few days. The districts namely Banswara, Baran and Jhalawar received fairly widespread to widespread heavy rainfall 5 to 6 days during the whole season while Karauli, Sirohi, Pratapgarh, Kota, Dungarpur, Jalore and Pali districts observed similar type of rainfall on 2 to 3 days.

Fig. 17 Tehsil level seasonal rainfall distribution – Monsoon 2013 17

In most of the districts, all tehsils received either excess or normal rainfall during the whole Monsoon season. The worst effected districts with less rainfall during this season were Sirohi , Bikaner and Sriganganagar . Out of 6 tehsils in 3 tehsils got deficit rainfall, out of 9 tehsils in Sriganganagar 5 tehsils got deficit rainfall and out of 7 tehsils in 3 tehsils got deficit rainfall. One to two tehsils also recorded deficit rainfall in Alwar, Bharatpur, Bhilwara, Jaipur, Sikar, Barmer, Hanumangarh districts. Overall , out of 245 tehsils in the state , 128(52%) tehsils got excess rainfall , 94 (38%) normal , 23 (10%) deficit and no tehsil observed scanty rainfall.

Fig.18 Tehsil wise Seasonal Rainfall Distribution Fig. 19 Daily Average Rainfall Distribution Over East Rajasthan ( Monsoon 2013)

Fig. 20 Daily Average Rainfall Distribution Over West Rajasthan (Monsoon 2013) Fig.21 Daily Average Rainfall Distribution over Rajasthan (Monsoon 2013)

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Fig. 22: Daily rainfall intensity distribution over East Rajasthan –Monsoon 2013

Fig. 23: Daily rainfall intensity distribution over West Rajasthan –Monsoon 2013

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LESS 10 10--20 20--50 50--100 GREATER THAN 100 Fig. 24 District Wise Weekly Rainfall Distribution over Rajasthan Monsoon 2013

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6. Long range forcast of Monsoon–2013 over NW India

The southwest monsoon rainfall for the period June to September over northwest India was predicted normal (94%) of LPA with a model error of +8%. The actual rainfall for this broad region and the State (part of NW India) were 109% and 128% respectively of LPA. Thus forecast for the season rainfall over northwest India was underestimated to the actual rainfall by 15% of LPA.

7. Performance of Monsoon 2013 over Rajasthan

The monsoon rainfall had been very satisfactory from all aspects on both temporal and spatial scale over the whole state. The Monsoon 2013 was far better than the last year Monsoon 2012. This was the fourth consecutive year when monsoon had been good over the state. This was the excess rainfall monsoon year for the state.

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