Delhi drenched, but clouds retreat to south-east


Vinson Kurian

Thiruvananthapuram, June 30 India Meteorological Department (IMD) declared the onset of monsoon over entire Uttar Pradesh and Delhi on a day when, ironically, the causative clouds beat a hasty retreat from the region overnight.
Satellite maps showed the clouds massing up instead over east and southeast India, presaging widespread rainfall over these regions during the next few days.
This provided further proof to the fact that the “obligatory” rains in the northwest over the past two days were inspired more by dominant westerlies as they interacted with available weak easterlies.
The interaction has since got concentrated to east and southeast in tandem with the eastward movement of trough in the westerlies.
Dr Akhilesh Gupta, expert operational forecaster and Adviser to the Ministry of Science and Technology, had indicated to Business Line the scope of this interaction at least two weeks ago.
PRE-MONSOONAL The rains have been pre-monsoonal in nature; pure monsoonal showers would take at least a week more to materialise consequent on the formation of a ‘low’ near the head Bay of Bengal around July 7.
The IMD said that the monsoon has advanced into Uttar Pradesh and Uttarkhand, Jammu and Kashmir, Himachal Pradesh, Delhi, more parts of east Rajasthan and many parts of Punjab and Haryana.
It was vigorous in Bihar and active in Haryana and Punjab but subdued over Tamil Nadu and north interior Karnataka during the 24 hours ending Tuesday morning.
Conditions are favourable for further advance into remaining parts of Punjab and Haryana and more parts of Rajasthan during the next two days.
MAJOR BOOST Meanwhile, seasonal rains are expected to get a substantive ‘kick’ with the next big surge from July 7. Both Arabian Sea and Bay of Bengal would throb with intense activity and witness ‘cyclogenesis’ (birth of ‘low’).
International models too, attest to the progressive strengthening of the current, backed up as it would be by a weather-booster Madden-Julian Oscillation (MJO) wave transiting into the southwest and equatorial Indian Ocean.
Predictions based on Empirical Wave Propagation technique by the Climate Prediction Centre (CPC) of the US National Weather Services suggests that the wave would initially make its presence felt from July 4 to 9.
It would be in peak activity between July 9 and 19, assuring widespread to fairly widespread rains all over India.
JULY RAINS If this were to pan out as forecast, IMD may well be faced with the ‘pleasant task’ of reviewing its below normal-rain outlook for July.
In this case, the peak activity is indicated during June 25 to July 9, with the northeast Arabian Sea resonating during July 2 to 9. It is likely that a ‘low’ might get thrown up here also.
The IMD has said that the prevailing offshore trough from Konkan coast to Kerala coast would continue to cause widespread rainfall activity with isolated heavy to very heavy falls along the west coast for five more days.
Numerical weather prediction models suggest widespread rainfall with isolated heavy to very heavy falls for east Uttar Pradesh, Bihar, Sub-Himalayan West Bengal, Sikkim and the North-Eastern.
Heavy to very heavy rainfall has been warned of at a few places with isolated extremely very heavy over Assam, Meghalaya and Arunachal Pradesh during the next two days.