Current observations

The monsoon trough currently lies with its north west end over west Rajasthan and extends south eastwards through Uttar Pradesh, Bihar , West Bengal and to the BoB. It's north western end has grown weaker due to an upper air anticyclonic cell over east Pakistan. A moderate pulse of western disturbance may lie over south west Afghanistan and progress eastwards to J&K around 18 th September and interact with the monsoon trough.

Fresh Depression

Another fresh mid tropospheric low may develop over central Bay of Bengal and may progress westwards and lie over central peninsular India on 13 th September. A mid-tropospheric low may lie over Bihar and get embedded in the monsoon trough.. Another low is likely to develop over south central BoB around 20 th September off the Andhra Pradesh coast around 2nd September and propagate westwards .

weather system affect over states - Graphics Metbeat Weather

An upper air circulation may lie over west Madhya Pradesh. A north- south shear zone may lie extending from interior Maharashtra to south Tamil Nadu from 16 th to 18 th September. Another upper sir circulation is likely to develop off the Andhra Pradesh coast around 20 th September.

Preliminary conditions for monsoon withdrawal may develop over the north western parts of India from the 21 st September as upper level anticyclonic cell may consolidate and gradually dissipate the north western heat low. An upper air circulation may lie over south west Arabian sea from 14 th to 17 th September.

General forecast for the upcoming days

Under the influence of the above mentioned synoptic factors, the rains would be patchy on the north western parts as the rain bands may retreat to the western, east-central and north eastern regions. However , the pockets in Uttrakhand , and west Uttarpradesh could expect moderate to heavy rainfall due to a mid tropospheric low that may lie over Bihar and adjoining parts of Uttrakhand around 14 th to 16 th September.

Due to the low over the BoB and the east- west and north - south shear zones there may be a strengthening of the lower level westerlies in coastal Maharashtra, Konkan, coastal Karnataka and Kerala. While pockets in Madhya Maharashtra, Marathwada , Vidarbha regions of Maharashtra, southern pockets of Madhya Pradesh, Chattisgarh and Jharkhand could get good spells of rain.

Under the influence of the above synoptic conditions, heavy rainfall may be expected over Purnea , Patna , Darbhanga, Birgunj and Munger in Bihar, Dibrugarh , upper Assam in Assam, on 10 th, 11 th & 17,18 th September, Dehradun, Uttarkashi, Pauri Gharwal, Ranikhet, Mukteshwar, Haldwani, Bageshwar , Chamoli in Uttrakhand from 13th to 15 September, Sitapur, Balrampur, Pilibhit, Muzaffarnagar, Saharanpur, Meerut in Uttar Pradesh from 13 th to 15 th September , and in Punjab , Haryana Himachal Pradesh &:J&K , between 14 th and 17 th September .

Due to the upper air circulation and associated low moving towards Madhya Maharashtra, Ratnagiri , heavy rains may once again be expected in Nagpur , Nanded, Washim, Amaravati , Chandrapur, Balharsha, Akola in Vidarbha, Kolhapur, Nashik, Igatpuri , in Madhya Maharashtra, Indore, Jabalpur , Katni, Khandwa, in Madhya Pradesh from 13 th to 16 th September, Mumbai, Goregaon, Dombivli, Roha on 14 th & 15 th September.

In the south peninsular India, very heavy rainfall may be expected in Hyderabad , Mahbubnagar, Kurnool, Warangal, Khammam & Manuguru in Telangana, Vijayawada, Eluru, Vizag from 13 th to 14 th September.

In Karnataka, the north interior pockets of Bellari, Gadag, Hubbali, may get heavy thundershowers or rains on 13 th, 14 th 17 th September. The rain bands would move to Bangalore with heavy spells of rains from 18 th to 20 th September.

The offshore western monsoon trough has weakened though it is not technically a monsoon break. An upper level anticyclonic cell over east Afghanistan may interfere with monsoon moisture flux and hence rainfall activity would be subdued.

The offshore western monsoon trough is likely to become active along the western coast around 15 th September due to the low pressure lying over the BoB and the presence of a north - south shear zone.

All India regionwise rainfall forecast

Union territories of J& K and Ladakh

Extremely heavy rains may be expected in Jammu, Kishtwar, Sambar, Padum, Kathua, Udhampur, Anantnag, Ramban region on 19 th & 20 th September due to a moderate pulse of western disturbance embedded in the upper westerlies and an associated trough interacting with monsoon trough. The upper reaches of Kargil and Skardu in the Zanskar ranges may expect blizzard and heavy snowfall.

NCR Delhi, Punjab and Haryana, Uttrakhand and Himachal Pradesh

Extremely heavy rains are likely in Gurdaspur, Jalandhar , Faridkot, Patiala, Ludhiana, Karnal, Kurukshetra & Chandigarh in Punjab & Haryana from 16 th to 18 th and moderate to heavy rains in NCR Delhi and various adjoining areas on 19 th & 20 th September. Fresh spell of heavy rains are likely in Uttrakhand and Himachal Pradesh on 13 th & 14 rd September.

Pockets like Shimla, Mandi, Chamba, Kangra,, Dharamshala in Himachal Pradesh and pockets in the Pauri - Gharwal, ranges, particularly, Uttarkashi , Karnaprayag and Chamoli in western Gharwal Himalayas likely to get widespread heavy rains on the above dates.

The north- east, , Gangetic west Bengal, Odisha and Sub-himalayan west Bengal regions

Under the influence of an upper air circulation lying over upper Assam moderate to heavy rains are likely in Assam, upper Assam, Guwahati, Goalpara , Dibrugarh and Meghalaya , Alipurduar, Darjeeling, Sikkim, Kalimpong in Sub-himalayan west Bengal from14 th to 17 th September

Bihar & Jharkhand

Due to a east- west shear zone running from Uttar Pradesh to Assam and an upper air circulation lying over Jharkhand, along with the low over BoB , very heavy rains may be expected in Patna, Birgunj, Darbhanga Sasaram Purnea & Gaya, in Bihar from 14th to 18th September and in Rourkela, Ranchi , Dhanbad, Jamshedpur in Jharkhand from 14th to 17 th September.

Central India

Under the influence of east -west shear zone extending from Madhya Pradesh to Jharkhand and a north- south shear zone extending from Madhya Pradesh to Tamilnadu through interior Maharashtra & the fresh monsoon low lying over BoB around 10th September, isolated heavy thundershowers or rains may be expected in , Korba, Ambikapur Raipur in Chhattisgarh, Chandrapur, Nagpur, & Amaravati in Vidarbha, Maharashtra on 13 th & 14 th September.

In coastal Maharashtra , Dombivali , Kalyan, and pockets like Nashik, Itarsi , Kolhapur in Madhya Maharashtra , and Ratnagiri may expect very heavy rains from 14 th to 17th September.

Andhra Pradesh, Telengana and Karnataka

Due to the westward movement of the low over central BoB and the associated north- south shear zone, very heavy rains are likely in pockets like Hyderabad, Khammam, Ramagundam, Manuguru & Warangal in Telengana and in Vijayawada, Kakinada , Kurnool , Nandyal, Muchlipatanam & Vizag in Andhra Pradesh, from 13th to 15 th September and in coastal south Karnataka and from 14th to 16th September and in south interior Karnataka including Bengluru on from 17 th to 20 th September.

Kerala

The offshore western monsoon trough which has been remaining weak is likely to become moderately active from 15 th September under the influence of the low moving westwards from the BoB and also due to an upper air circulation that may lie over south west Arabian sea from 14 th to 17 th September.

The rains in Kerala may be mostly in eastern pockets which may be scattered and in short spells . Due to easterly anomalies and moisture flux convergence in Tamilnadu caused by leeward troughing and a north- shear zone extending from Madhya Pradesh to Tamilnadu eastern pockets of Kozhikode ,Wayanad, eastern pockets of central and south Kerala may expect thunder showers from 17 th to 20 th September.

There could be thunder showers or rains mainly all along the eastern parts extending from Kannur upto Thiruvananthapuram on these dates.

Tamilnadu

Due to easterly anomalies and moisture flux convergence caused by leeward troughing and a north- shear zone extending from Madhya Pradesh to south Tamilnadu , isolated heavy rains are likely over Trichy, Dindigul, Madhurai and in suburbs of Chennai like Vellore and Chetpat and in Chennai , Puducherry on 13 th & 19 th September.

As usual Valparai, the western flanks of Nilgiris , Theni and Tenkasi would receive moderate rains from 13 th to 16 th September and heavy rains on 19 th & 20 th September .

Photo credit: Business Standard