Monsoon likely in northwest, central India this week: IMD
The monsoon trough (a low-pressure line), which had shifted northward to the Himalayan foothills bringing extremely heavy rains of over 20 cm to north-eastern and eastern states has started moving southward, the India Meteorological Department said on Sunday.
With the moving of the monsoon system, active monsoon rains are likely to resume over northwest and central India between July 14 to 16, the IMD said.
The western end of the monsoon trough is presently passing through Ganganagar, Delhi and Bareilly; while the eastern end continues to run close to the foothills of Himalayas, according to IMD.
A cyclonic circulation is lying over east Bihar and neighbourhood. This, in addition with the convergence of south-westerly and southerly winds from Bay of Bengal in the lower tropospheric levels, is likely to continue over northeast and adjoining east India during next two days, the Met department said in its forecast.
Widespread and very heavy rains will continue over northeast India, West Bengal, Sikkim, Bihar and adjoining east Uttar Pradesh for next five days, but the intensity of rainfall is expected to be lower than last week.
Moderate to severe thunderstorm and lightning is likely over many parts of Uttar Pradesh and Bihar over the next 12 hours, according to IMD’s Sunday bulletin. The deluge in Arunachal Pradesh (over 50 cm on Friday and Saturday) and Assam is likely to reduce further in the next 24 hours.
Since the western end of the monsoon trough is running close to Delhi, light rain in different parts of the national capital is expected on Sunday, followed by more intense rains on July 14 and 15. “As the monsoon trough shifts southwards, rains are expected in Delhi also but it will be in light to moderate category. Overcast skies will continue. Wind direction, which has been largely westerly because of the trough shifting northward, will switch to easterly now,” said Kuldeep Shrivastava, head, regional weather forecasting centre.
Since June 1, three subdivisions have received large excess (60% excess or above) rains; 12 have received excess rains; 15 are in normal while six are deficient. According to Central Water Commission as on July 11, 30 stations (one in Arunachal Pradesh, 14 in Assam, one in West Bengal, 10 in Bihar and four in Uttar Pradesh) were flowing in Severe Flood Situation and 20 stations (nine in Assam, five in Bihar, three in Uttar Pradesh, three in West Bengal, one in Daman & Diu and one in Arunachal Pradesh) were flowing in Above Normal Flood Situation.
Teesta river in West Bengal, Kosi and Mahananda in Bihar, Siang at Passighat in Arunachal Pradesh and Brahmaputra in Assam continue to be in severe flood category.
The country has received 14% excess rain this monsoon season -- 20% excess in central India, 16% excess in south Peninsula, 14% excess in east and northeast India -- and 3% deficient over northwest India.
IMD scientists said the distribution of rains have been largely even this year. The standardised precipitation index (an index to measure drought) shows many districts in eastern, central and peninsular India are in severely wet category while others are mildly wet.
“The western end of the monsoon trough has started shifting southwards from the foothills. Stations reporting extremely heavy rainfall in northeast India particularly Assam, Arunachal Pradesh and Meghalaya have reduced in the last 24 hours. All of these areas were flooding. But we have to watch for one more day as the eastern end of the trough is still in the foothills. One station in Sub Himalayan West Bengal has reported 43 cm rain (extremely heavy) on Saturday. Once the trough shifts southwards, monsoon rains will gradually resume over northwest and central India,” said RK Jenamani, senior scientist at National Weather Forecasting Centre.
“This monsoon, the Arabian Sea has been unusually active starting with cyclone Nisarga which helped with monsoon onset. The moisture feed from Bay of Bengal in comparison is negligible. An intense low-pressure system also over Saurashtra last week which brought extremely heavy rains there. Another feature of this monsoon is that the monsoon trough is mostly north of its normal position this year so the northeast has got a lot of rain. Not many low-pressure systems have formed over Bay of Bengal which is a bit unusual,” he added.
Last week, Okha in Gujarat received record 48 cm rainfall on July 7. On July 5, Khambala, Kalyanpur and Porbandar recorded 49 cm, 36 cm and 29 cm, respectively. Thane and Mumbai also recorded extremely heavy rains on July 3, with 17 cm in Mumbai’s Colaba and 38 cm in Thane.