Monday, May 10, 2010

Westerly system moving away, heat seen building

A prevailing western disturbance that spawned wild cat dust storms and thundershowers over northwest India is in the process of moving away east-north-eastwards and out of the country.

This is expected to ‘clear up' the skies over the region and, in the process, lead to a spike in maximum day temperatures over the next two to three days.


According to India Meteorological Department (IMD), Gangetic plains and parts of central India would bear the brunt of the heat during this period.

The European Centre for Medium-Range Weather Forecasts (ECMWF) is of the view that the heat would push to the northwest sooner than later. This is because a temporary ‘blockade' is being erected in the path of the western disturbances in the higher levels of the atmosphere across the international border.

The IMD has said that a fresh western disturbance is likely to affect western Himalayan region from Monday.

If the ECMWF signal is any indication, this may not be able to make much impression on local weather towards the immediate south.

Given this context, it suggests that the region northwards from Madhya Pradesh extending east into Uttar Pradesh and west-north-west to Delhi, Haryana, east and south-west Rajasthan and Punjab would witness top heat during the period ending May 19. Only south peninsular India and the north-east would be spared from the intense heat for varying but strictly local reasons, the ECMWF forecasts say.


As if on cue, the US National Centres for Environmental Prediction says that convective rainfall would be confined to these two regions during the period until May 16, before gradually scaling up during the week that follows (May 18-25). Forecasts given out by the Climate Prediction Centre of the US National Weather Services too share this view.

Meanwhile, on Sunday, a weather-making northeast to southwest trough ran down from east Madhya Pradesh to Lakshadweep across interior Maharashtra and Karnataka.

A second trough ran west to east from east Madhya Pradesh to Assam across Jharkhand, north Gangetic West Bengal and north Bangladesh with an embedded cyclonic circulation over Bangladesh. An induced cyclonic circulation lay over central Pakistan with a trough from this system running down to north Rajasthan.

Satellite imagery showed convective (rain or thundershower-producing) clouds over parts of Assam, Arunachal Pradesh, south Bay of Bengal and south Arabian Sea.

Low to medium clouds were seen over parts of south Andaman Sea, western Himalayan region, south peninsular India and remaining parts of the Northeastern States.

The IMD has warned that thunder squalls would occur at some places over Jammu and Kashmir, Himachal Pradesh, Uttarkhand, Bihar, Jharkhand, West Bengal, Sikkim and the Northeastern States during the next two days.

Isolated thunder squall may occur over Rajasthan, Haryana, Chandigarh, Punjab and west Uttar Pradesh during the next 24 hours.

Forecast valid until Wednesday said that fairly widespread rain or thundershowers would occur over Assam, Meghalaya and Arunachal Pradesh while being scattered over Nagaland, Manipur, Mizoram and Tripura.

Scattered rain or thundershowers would occur over Kerala, coastal and south interior Karnataka, Lakshadweep and Andaman and Nicobar Islands. They would be isolated over Andhra Pradesh, north interior Karnataka and Tamil Nadu.

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