The India Meteorological Department (IMD) has maintained its forecast for ‘normal' rainfall during the ongoing South-West monsoon - quantified earlier as 102 per cent of the long-period average (LPA).
Vigorous rainfall during the last 10 days ending Wednesday (July 28) has helped the country come out of an unexpected lean patch in early July.
JULY RAINFALL
The July rainfall has since improved to 101 per cent, taking the seasonal recorded precipitation level to 95 per cent of the LPA as on Wednesday (July 28, and counting).
Precipitation during August-September is expected to be 107 per cent, which is significantly higher than that during the first two months of the season, according to Dr Ajit Tyagi, Director-General, IMD.
Dr Tyagi told newspersons in New Delhi on Friday that rainfall during the first-half was hampered by what he described as an ‘anomaly' in the Bay of Bengal.
Though the flows have been good over the Arabian Sea, the uncharacteristically muted Bay could not hold its end up.
Thus, while rain-driving depressions were simply absent, low-pressure areas had spun up at the least favoured of locations (southern than normal) in the Bay denying them the ‘carry' needed to drive rains inland.
HEAVY RAINS
The Arabian Sea flows, in the meanwhile, have been dumping heavy falls over the west coast even as they ventured into north-west India, which in normal case would be the natural fiefdom of monsoon easterlies from the Bay.
But the Bay anomaly ensured that, instead, moisture-laden southwesterlies from the north-east Arabian Sea fan their way into north-west India.
They interacted profusely with the western disturbances to unleash a torrent that inundated many parts in Punjab, Haryana, Delhi and parts of Rajasthan.
In an updated outlook for August and September, the IMD said that rainfall during the second half of the season is likely to be normal.
Quantitatively, rainfall for the country as a whole during August to September is likely to be 107 per cent of the LPA with a model error of plus or minus seven per cent.
Latest model forecasts from a majority of the dynamical and statistical weather models indicate ‘very high' probability (about 80 per cent) for monsoon-friendly La Nina conditions to continue during the remaining part of the season.
The La Nina is in general is associated with normal or above normal rainfall during the season as a whole, especially during the second half.
But the IMD added that while three geographical regions (Northwest India, Central India and South Peninsula) are likely to receive normal rainfall during this period, it would be below normal over Northeast India.
In its update on Friday, the IMD said that the low-pressure area located to over East Madhya Pradesh and adjoining west Madhya Pradesh has triggered another wet spell over the west coast and parts of peninsular India.
The system is likely to move west-northwestwards and herald rains into Central India and Northwest India, going forward.
A special rain alert issued by the IMD has warned that isolated heavy to very heavy rainfall would occur over North Madhya Maharashtra, Chhattisgarh, Vidarbha and Marathwada on Saturday.
Forecast valid until Monday spoke about the possibility of isolated heavy to very heavy rainfall over Uttarkhand, West Uttar Pradesh, Madhya Pradesh, Konkan, Goa, Coastal Karnataka, Arunachal Pradesh, Assam, Meghalaya, Sub-Himalayan West Bengal and Sikkim.
Widespread rain or thundershowers would occur over the West coast. Fairly widespread rain or thundershowers are likely over Himachal Pradesh, Uttarkhand and adjoining northern plains, Central and Northeast India.
Fairly widespread rain or thundershowers would occur over Madhya Pradesh, Marathwada on Friday and decrease thereafter.
As per weather blog archieve of july 25 2009,
ReplyDeleteA La Nina, the oposite of an El Nino, is generally beneficial for the south-west monsoon but could it weaken the north-east monsoon? Bad for water starved TN/south interior karnataka, Rayalseema.