Tuesday, June 22, 2010

North-west may have to wait beyond July 6 for monsoon

Northwest India may have to wait beyond July 6 to see the onset of monsoon rains, according to latest updates by international models.
The US National Centres for Environmental Prediction (NCEP) is of the view that entire Rajasthan, parts of west Madhya Pradesh, Punjab, Himachal Pradesh, Uttarkhand and Jammu and Kashmir may be denied timely onset of the rains.
However, west Uttar Pradesh, Delhi and Haryana may just be able to slip themselves under cover during this period.

Northwest India, however, is shown in positive territory, assessed at 25 per cent above normal rainfall for the season (June 1-17) until now. This was largely due to non-seasonal rains dumped over west Rajasthan and adjoining areas by an incoming circulation from erstwhile super cyclone, Phet, early this month, as also by passing western disturbances.
South peninsula is shown at +22 per cent and central India -3 per cent in terms of cumulative rainfall received during this period but northeast India lagged at -22 per cent.
The normal timeline for monsoon to cover the entire landmass is June 30, but this could now get stretched by at least a week, if not more, according to NCEP. The monsoon covers south peninsula, east and central India in calibrated movements mandated by helpful churns mostly in the Bay of Bengal. It then turns west-northwest to head into Rajasthan, Punjab and Haryana, among others, forming part of northwest India.

The Bay of Bengal appears to be the weakest link for now in the vulnerable monsoon chain underpinning its spatial and temporal spread.

India Meteorology Department (IMD) too accepts this fact saying in its latest forecast update that a monsoon-boosting ‘low' might take shape only late this week (around Friday).
But the European Centre for Medium-Range Weather Forecasts sees northwest Bay of Bengal (as against Head Bay), which is not ideal for monsoon to move west-northwest.
Instead, the system might cross the Andhra Pradesh-Orissa coast and head west (as against west-northwest) into east-central and adjoining central India, Maharashtra and Mumbai-south Gujarat, before slipping into the Arabian Sea by June 30.
In a marked deviation from this outlook, though, the NCEP says the system in the northwest Bay might initially track a little east-northeast along the coast and cross the West Bengal coast.
This (around the head Bay) is the ideal position for it to swing the monsoon current west-northwest into east India, covering West Bengal, Jharkhand, Chhattisgarh, Uttar Pradesh and Madhya Pradesh during the week ending July 6.
NCEP weather chart also shows a counterpart spinning up from the Arabian Sea and setting up a rendezvous with the incoming Bay system over land. Even this would not be enough to take the rains into Rajasthan and other places in the northwest.
According to monsoon experts here, they would not be surprised to find on retrospect that these areas have had to wait until July 10 to see the monsoon unfold. These areas would probably need to wait for the next system to get initiated in the Bay of Bengal, of which no clear forecasts were available from any model on Sunday.
The International Research Institute for Climate Prediction at Columbia University sees possibility of heavy to very heavy rains over coastal Karnataka, Konkan and northeast India during the six days ending Thursday.
The IMD too has said in its outlook for the week that the monsoon would be weak over the country except these two regions mentioned by the IRI. In a warning valid for the next two days, the IMD said that isolated heavy to very heavy rainfall would occur over Assam, Meghalaya and Arunachal Pradesh. Heavy rainfall is likely over Nagaland, Manipur Mizoram, Tripura, Konkan, Goa and coastal Karnataka also during this period.
The outlook valid until Wednesday spoke about the possibility of widespread rain or thundershowers over Konkan, Goa and coastal Karnataka.
Fairly widespread rain or thundershowers are likely over the Northeastern States, West Bengal, Sikkim, coastal Andhra Pradesh, Kerala, Lakshadweep and Andaman and Nicobar Islands. The rains would be scattered over Vidarbha, interior Karnataka, Telangana and Rayalaseema, the IMD said.

No comments:

Post a Comment