Tuesday, September 07, 2010

Ocean signals indicate another weak monsoon phase

Ocean signals indicate that the monsoon may be going into a weak phase from around the weekend.
It is about time too, according to Dr P.V. Joseph, eminent researcher and author on meteorology and a former director of India Meteorological Department (IMD).

Speaking to Business Line on Monday, he said active monsoon conditions have been prevailing over the last two-week period.
This is normally the extent to which these conditions can sustain.
But it is the weak monsoon phase that paradoxically brings rains to East and Northeast India, which have been witnessing below normal rains right through the season.
Viewed in this context, the weak phase would go to ensure ‘spatially justified' pattern of rains by bringing rain where it matters most for the time being.
International models suggest that a monsoon-boosting Madden-Julian Oscillation (MJO) wave could set up clouding over Equatorial Indian Ocean and adjoining peninsular seas during the third week of September.
MJO waves ply in the upper levels of the atmosphere and have alternating dry and wet phases as they transit periodically from west to east.

The dry MJO phase invariably sets up the intra-season lean phases while the wet phase is responsible for triggering monsoon onsets and associated weather systems (low-pressure areas and depressions).
According to the Jones Model, the progressively weakening MJO phase will start reversing from September 18 before culminating in an active phase for five days from September 23.
The Empirical Wave Propagation method applied by the US National Centres for Environment Prediction (NCEP) says that it would be a largely MJO-neutral phase going forward before an essentially dry phase sets in by September 27.
The NCEP has forecast rains for mostly East India and parts of Central and Northwest India during the week ending September 13. But a big chunk of the rains are shown to fall over the Bay of Bengal waters.

Meanwhile on Monday, an IMD update said that widespread rainfall was reported from Konkan, Goa and Coastal Karnataka during the 24 hours ending Monday morning.
It was fairly widespread over Himachal Pradesh, Uttarkhand, Haryana, west Uttar Pradesh, East Rajasthan, Gujarat, West Madhya Pradesh, Interior Maharashtra, Chhattisgarh, West Bengal, Sikkim and the Northeastern States.
Satellite cloud imagery showed the presence of convective clouds over parts of Uttar Pradesh, East Rajasthan, Chhattisgarh, Orissa, Andhra Pradesh, the Northeastern States, Central Bay of Bengal and Andaman Sea.

IMD has had some ‘minor trouble' uploading links to some satellite products over the past few days.
It is in the process of retrieving the links, according to the office of the Deputy Director-General, Satellite Meteorology. But it refused to elaborate further.
A heavy rain warning for the next two days said that isolated heavy to very heavy rainfall would occur over Uttarkhand, West Uttar Pradesh and South Haryana in Northwest India.
Over the rest of Central and Peninsula India, the warning is valid over Orissa, North Coastal Andhra Pradesh, Telangana, South Chhattisgarh, Vidarbha, South Madhya Pradesh, Konkan, Goa, Coastal Karnakata, Sub-Himalayan West Bengal, Sikkim, Assam, Meghalaya and Arunachal Pradesh.
Extended outlook until Saturday spoke about the possibility of continued fairly widespread rainfall activity over most parts of the country outside of Interior Peninsular India, where it may be scattered.

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