Weather report: As IMD announces onset of Monsoon over Nicobar, pre-Monsoon rains to strengthen across India

Monsoon 2023 is officially here, on 19 May the Indian meteorological department announced the onset of the South West Monsoon over Nicobar Island. As per the agency the Northern Limit of Southwest Monsoon continues to pass through 5°N/85°E, 6.5°N/90°E, Nancowry and 10°N/98°E as of 21st May and conditions are said to be favourable for further advance of southwest monsoon into some more parts of south Bay of Bengal, Andaman Sea and Andaman and Nicobar Islands during next 2-3 days. [caption id=“attachment_12630292” align=“alignnone” width=“300”] The northern limit of monsoon as per IMD till 20 May 2023[/caption] But does the declaration of the onset make sense? As analysed the surface (850 hpa) and upper level (500 - 700 hpa) winds over the southern Andaman and Nicobar island is still blowing from the northwest, the south west winds are yet to start, there has been no significant moisture content in atmosphere or cloud cover over the island as per the satellite imagery, the surface rainfall at the nearest observatory has been NIL on 19, 20 and 21 May - The data is bit off for commencement of the monsoon in south Andaman. [caption id=“attachment_12630312” align=“alignnone” width=“314”] Satellite imagery on Sunday afternoon indicates clear weather across Andaman and Nicobar island with no cloud cover[/caption] When will the monsoon hit the islands then? As the cross equatorial winds seem strengthening, with Inter tropical convergence zone moving north around 24 May along with south westerly setting in at the island coupled with higher probability of rains by 25 May, the declaration of south west monsoon over the island should be ideally declared around 25 or 26 May, 2023. When will Monsoon arrive over the Indian Mainland? The sluggish start of monsoon will at least take another two weeks to recover, with a slight delay south west monsoon is expected to hit Kerala between 3 and 7 June. Development of key features during the first week of June 2023: • The sinking air due to Madden Julian Oscillation will fade out. • Cross equatorial winds will strengthen, inter tropical convergence zone will move up towards Kerala. • Somali Jet streams (Upper level eastern winds) are seen around that period. • Most importantly, an increased probability of precipitation and commencement of South west winds is expected over Kerala during the period of 3rd to 7th June, 2023, potentially monsoon will onset during these days. Parts of North India experienced pre-monsoon rains around the mid week accompanied with strong Dust and Hail storms. On the midnight of 18 May maximum wind gust reported from some of the stations of North India: Sadulpur (Hisar): 94.4 kmph Kaul (Kaithal): 88.9 kmph Fatehabad: 88.9 kmph Pantnagar: 79.6 kmph Rainfall in the span of 24 hours ending 8:30 AM on 18 May, 2023: Karnal: 26mm Rohtak: 15mm Pilani: 14mm Meerut: 13mm Hisar: 11mm Dehradun: 11mm New Delhi: 10mm Ludhiana: 8mm Chandigarh: 7mm Ganganagar: 6mm Ambala: 6mm As soon as the western disturbance moved away hot and dry winds from north west India started blowing across the interiors of the country along with clear skies, temperature rose and heatwave conditions emerged over some parts of north west India on Saturday, reported maximum temperature as follows, Bikaner: 45.5°c Jhansi: 45.1°c Prayagraj: 44.8°c Jaisalmer: 44.5°c Khajuraho: 44.5°c Akola: 44.4°c Churu: 44.4°c Phalodi: 44.2°c Barmer: 44.1°c Nandyal: 44.1°c Wardha vidarbha: 44°c Kota: 43.8°c Jalgaon: 43.5°c Chandrapur: 43.4°c Sri Ganganagar: 43.4°c Parbhani: 43.4°c Daltonganj: 43°c Jeur: 43°c Khargone: 43°c Nagpur Airport: 43°c Nowgong: 43°c Rajnandgaon: 43°c Ratlam: 43°c Varanasi: 43°c India’s north eastern states have received fairly good amount of rains in the past few days, this comes after a deficient pre monsoon season so far, rainfall reported in the span of 24 hours ending 8:30AM on 20 May: Silchar: 72 mm Mazbat: 52 mm Kailashahar: 20 mm Cherrapunji: 16 mm Dhubri: 13 mm North Lakhimpur: 10 mm Gangtok: 7 mm Rainfall reported in the span of 24 hours ending 8:30AM on 21st May: Cherrapunji: 102mm North Lakhimpur: 76 mm Dibrugarh: 49 mm Gangtok: 46 mm Dhubri: 32 mm Jorhat: 28 mm Tezpur: 26 mm Goalpara: 20 mm Guwahati: 13 mm Despite North east India saw a slight recovery in rains, pan India rains have been less in the past week, the pre monsoon seasonal total so far from 1 March till 20 May is at a total of 120.0 mm against the normal of 105.9 mm, the departure from normal for the country as whole stands at +13 per cent above normal. Subdivision wise seasonal rainfall till 20th May, 2023: • Southern Peninsula: Actual 140.7 mm against the average of 93.0 mm, +51 per cent departure from normal. • East & North East India: Actual 198.9 mm against the average of 294.9 mm, -33 per cent departure from normal. • North West India: Actual 113.4 mm against the average of 101.8 mm, +11 per cent departure from normal. • Central India: Actual 76.6 mm against the average of 27.7mm, +176 per cent departure from normal. [caption id=“attachment_12630322” align=“alignnone” width=“408”] Satellite imagery on Sunday afternoon indicates clear weather across Andaman and Nicobar island with no cloud cover[/caption] Current synoptic weather features influencing weather in India as on 21 May, 2023: • The trough in middle and upper tropospheric westerlies with its axis at 5.8 km above mean sea level now runs roughly along Long. 86°E to the north of Lat. 25°N. • The trough from west Bihar to north Telangana across Chhattisgarh at 0.9 km above mean sea level persists. • The trough runs from North Interior Karnataka to south Tamilnadu at 0.9 km above mean sea level. • A fresh Western Disturbance likely to affect Northwest India from 23rd May 2023. All India weather forecast till 28 May: As the dry weather made a comeback over north and central India this weekend, heatwave conditions made a short comeback but also expected to take a quick exit next week. A series of active western disturbances to affect most parts of North India starting from 23 May till 27 May. Under the influence of the active weather system widespread strong dust storms, moderate to heavy rains, hail are expected across Punjab, Haryana, Delhi NCR, Rajasthan, Uttar Pradesh, Madhya Pradesh, Jharkhand, Bihar, West Bengal, Chhattisgarh in those five days. This prolonged spell of rains will result in another period of cool temperature ranges next week, the maximum temperature anomaly can be as low as 10 to 14°c below normal, the month of May and the overall pre-monsoon season is expected to end with excess pre-monsoon precipitation numbers across North, East and Central India, Highly below normal temperatures in the peak summer month of May. [caption id=“attachment_12630332” align=“alignnone” width=“575”] Below normal temperature anomaly in May so far, the month is expected to end on more colder note[/caption] Northeast to continue the wet run Western disturbance along with the moisture pull from the Bay of Bengal will keep rains active across north east India in the upcoming week as well. Moderate to heavy rains expected in Sikkim, Arunachal Pradesh, Assam, Meghalaya, Mizoram, Manipur, Nagaland, Tripura during the period of 23rd to 28th May with possibility of very heavy rains in Meghalaya, Assam, Arunachal Pradesh during this period. The rainfall deficiency in north east India is expected to reduce by the month end and pre monsoon season might end on a near normal note. South to keep strong hold on rains We are nearly two weeks away from monsoon to commerce from southern states of the country, it is also the right time when pre-monsoon thunderstorms season sees the peak, the mornings and afternoon hours to be humid and hot followed by convective clouds developing in the evening hours to result in moderate rains and thundershowers in multiple cities of Kerala, Tamil Nadu, Karnataka, Andhra Pradesh and Telangana next week. The upcoming week till 28 May is expected to be washed out by heavy rains in multiple states of India except Gujarat, Maharashtra and Goa where rains will be significantly lesser and dry and hot weather to prevail. The author, better known as the Rohtak Weatherman, interprets and explains complex weather patterns. His impact-based forecasts @navdeepdahiya55 are very popular in north India. Read all the  Latest News,  Trending News,  Cricket News,  Bollywood News, India News and  Entertainment News here. Follow us on  Facebook,  Twitter and  Instagram.