Tuesday, December 29, 2009

Heavy rains in south as chill spreads over north-west India

An easterly wave active over the southern peninsula, especially over south-east Arabian Sea, has ramped up the north-east monsoon to ‘vigorous' status over Kerala.

In contrast, a relentless barrage of cold and dry northwesterlies sustained the chill over north and northwest India during the last 24 hours with no sign of abating anytime soon.

COLD WINDS

The strong northwesterly winds in the lower troposphere over the Indo-Gangetic plains would sustain themselves over the next two days as well, an India Meteorological Department (IMD) update said on Monday.

A feeble western disturbance would affect Jammu and Kashmir during this period and cause rain or snow over adjoining Himachal Pradesh also. But no large change in minimum temperatures is likely over plains of north-west India.

Given this, cold wave conditions are likely to continue over isolated places over Punjab, Haryana and East Uttar Pradesh during this period.

An update from the Chennai Met Centre said that heavy to very heavy overnight rainfall has been reported from many places over Kerala and south interior Karnataka during the last 24 hours ending Monday morning.

A few places over Lakshadweep, coastal and north interior Karnataka too received moderate rainfall while it was isolated over Tamil Nadu.

RAINS IN SOUTH

International models had forecast the ongoing rains over the west coast and adjoining west-central peninsula, which could gradually creep over to parts of central India and adjoining east India.

The causative cyclonic circulation tossed up by the easterly wave persisted over the Lakshadweep Islands on Monday supported at the ground level by the ‘warm pool' (28 to 30 deg Celsius) in the south-east Arabian Sea hugging the Kerala/Karnataka coast.

Prevailing westerly winds are sweeping moisture from this part of the sea into the hinterland where it is being dumped as rain. Kerala and adjoining south interior Karnataka benefited the most from these rains during the last 24 hours.

An IMD update on Monday has, however, said that a trough of low lay stretched from south-east Arabian Sea into the Karnataka coast.


This meteorological feature would allow moisture to be piped in and the rains to sustain over the mainland.

Forecast for the next two days said that rain or thundershowers are likely at many places over Lakshadweep and at a few places over Kerala and Karnataka. Isolated rain or thundershowers are likely over Tamil Nadu and Puducherry.

Another trough of low was located over south-west Bay of Bengal with a cyclonic circulation over coastal Tamil Nadu and adjoining south-west Bay. But the seawaters had cooled down considerably over this area curbing convection and rainfall.

The IMD has forecast isolated rainfall activity along the west coast and over central and adjoining east India and south peninsula during the next three days.

The US National Centres for Environmental Prediction (NCEP) has said in its outlook for the next seven days that rainfall up to 600 per cent above normal for this time of the year may get recorded over the southwest coast and the immediate interior.

Forecast for the following week suggested that south-west Bay of Bengal may erupt with activity once again with a likely low-pressure area wheeling in to cross the Chennai-south coastal Andhra Pradesh belt.

The European Centre for Medium-Range Weather Forecasts (ECMWF) too agrees with the outlook though it found the ‘low' mostly active around south-east Tamil Nadu and adjoining Sri Lanka.

The activity is shown as peaking around January 5 with the entire extreme south peninsular India and entire Sri Lanka getting ensconced within a trough of low pressure, with or without a ‘low'.

In the north, severe cold wave conditions prevailed in some parts of Haryana and Punjab while cold wave conditions were reported from isolated places in Jharkhand and east Uttar Pradesh.

Minimum temperatures are below normal by 4 to 6 deg Celsius over parts of Punjab and Haryana and by 2 to 4 deg Celsius over East Uttar Pradesh, Bihar, adjoining West Bengal, Orissa and Chhattisgarh, an IMD update said.

On Sunday, the lowest minimum temperature of -1.0 deg Celsius was recorded at Adampur in Punjab. A feeble western disturbance has been persisting over Jammu and Kashmir and neighbourhood.

IMD forecast until January 2 spoke about the possibility of isolated rainfall over parts of north-eastern states and extreme south peninsular India.

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