Friday, 15 May 2015

Monsoon to set in two days early over Kerala on May 30

The South-West monsoon is likely to set in over Kerala two days early on May 30, India Met Department announced this evening.
The prediction of the onset data assumes an error margin of plus or minus four days. The normal onset date is June 1. Importantly, the agency noted that the El Nino weather condition – a heating of ocean water in the eastern and central Pacific Ocean – is strengthening. Several international Met agencies in the US, Australia and Japan, have forecast a 70 per cent probability of an El Nino event in 2015.
The phenomenon is a cause for concern since it could lead to a second consecutive season of below-normal rainfall leading to drought conditions.
“El Nino conditions are concerning, they have been prevailing since March and is likely to strengthen during the monsoon and post-monsoon season. We will update the analysis for our forecast in June,” said an IMD official.
‘No El Nino worry’
While its prediction for the date of the monsoon onset – May 27 with the same margin of error - is similar to the Met Department’s, private weather forecasting agency Skymet disputed the assertion of an evolving El Nino.
The agency had earlier predicted that rainfall in 2015 would be 102 per cent of the Long Period Average (LPA) with an 82 per cent probability of normal-to-above-normal showers. It varied with IMD’s forecast of the South-West monsoon being below normal at 93 per cent of LPA, the average rainfall India received between 1951 and 2000 which stands at 89 cm.
“Analysing drought patterns through this and the last century, the year after the phenomenon is established has no drought. Last year, rainfall was 12 per cent below the LPA, it’s classified as a mild meteorological drought but the Government denied it. Our contention is that the El Nino episode is devolving this year,” said Jatin Singh, CEO, Skymet.
Skymet collates its information through 2,500 weather stations and satellite data and its computing model comprising 124 programs predicts no impact on the coming monsoon.
“The monsoon will be decent through June and will climb across the country. Our El Nino theorising is converging with our computing. The region is cooling off over the next 5-6 months,” said Singh.
Both agencies agreed that Indian Ocean Dipole (IOD) conditions, which also impact the monsoon in conjuction with the El Nino, were neutral.
Andaman onset
Earlier, the Met said that conditions are becoming favourable for the onset of monsoon at the extreme outpost of Andaman and Nicobar Islands over the next four days.
The islands at the extreme south-east are the first port of call for the monsoon.
Sri Lanka will be next, in a matter of 8-10 days followed by South West coast of India (Kerala) immediately thereafter.
The Thailand Meteorological Department said in its assessment that the winds are already south-westerly over the Andaman Sea clocking between 16- to 30 km/hr.
The wind speeds need to stabilise to around 30 km/hr for the monsoon onset to be declared in these parts.
‘Low’ delayed
Over Sri Lanka, the surface wind was variable in direction (or calm) and the speed was much slower at about 5- to 20 km/hr.
The wind was from the sea during day time along the coastal areas.
But the positive signals here included high atmospheric water vapour content.
Atmospheric pressure values over are also below monthly averages (making it easier for monsoon winds to blow in).
These announcements came on a day when India Met also withdrew the outlook for a low-pressure area over Lakshadweep (Arabian Sea).
Buzz in bay
Satellite maps showed a high-pressure area (dry air from the Arab desert) settling in over north and central Arabian Sea and delaying the genesis of the ‘low’ even as the parent cyclonic circulation persisted. According to the US National Centres for Environmental Prediction, the ‘low’ could materialise but would be pushed into the outer seas initially by north-easterly winds from the high-pressure area.
Meanwhile, the European Centre for Medium-Range Forecasts persisted with its outlook for a buzz developing over southwest Bay of Bengal off Tamil Nadu coast from this weekend.
It will undergo calibrated growth in the warm central Bay of Bengal and even could end up as a tropical cyclone over West Bengal coast with a projected landfall on May 23-24, the European agency said.
If this were to happen, the onset of monsoon is also likely to happen over the Kerala coast since the system is projected to travel all the way from off the south-east peninsula to the north-east.
Pacific typhoon
The benign presence of a another strong typhoon building sufficiently far away into the central Pacific and going further away south of the Korean peninsula would also help pull in the monsoon as a whole.
The European Centre saw cross-equatorial flows of monsoon off the Somali coast picking up after Sunday, leading up to the initiation of the disturbance in Bay of Bengal.

Source: BusinessLine

No comments:

Post a Comment