Fresh western disturbance coming ...

The active western disturbance that dominated the weather over the western Himalayas and the adjoining north-west India over the last two days is in the process of moving away to the east-north-east and out of the country.

But the arctic air and moisture brought in still lingers over the hills and plains and is expected to interact with easterly to south-easterly winds to cause precipitation over east and east-central India for the next few days.

‘LOW' ACROSS BORDER

A low-pressure area thrown up by westerly flows over central Pakistan and neighbourhood upstream may have become less marked but associated cyclonic circulation lay over north Pakistan. This would be able to rally additional moisture around itself and fling it across to northwest India.

An outlook by the US National Centres for Environmental Prediction (NCEP) suggested that northerly rains could even seep down beyond central India into the peninsula. South Madhya Pradesh, Vidarbha, Madhya Maharashtra and even north interior Karnataka could be impacted in this manner.

The weather would be further boosted by follow-up western disturbances expected to drift in this Friday and by mid-week next week, adding to the supply of moisture over the hills but less so over the plains. The European Centre for Medium-Range Weather Forecasts (ECMWF), too, agrees with this outlook.

This is likely to happen around the time when some sporadic weather is kicked up by the passage to the east of a Madden-Julian Oscillation (MJO) wave just to the south of Sri Lanka. This periodical wave is known to set up clouds and trigger precipitation, some of which is forecast to impact extreme southern peninsula later this week and into the next.

MERCURY FALLS

Meanwhile, during the 24 hours ending Wednesday morning, minimum temperatures fell by 3 to 5 deg Celsius over many parts of north-west India and by 4 to 8 deg Celsius over Gujarat as the active western disturbance moved away making the way clear for colder northwesterlies.

The minima (night temperatures) were below normal by 2 to 4 deg Celsius also over most parts of Punjab, Haryana, Rajasthan and Gujarat. But they were above normal by 3 to 5 deg Celsius over east India and Assam and Meghalaya ahead of the passage of the western disturbance over these areas.

Scattered to fairly widespread rainfall has occurred over Jammu and Kashmir, Himachal Pradesh, Uttarkhand and Uttar Pradesh until Wednesday morning, an update by India Meteorological Department (IMD) said on Wednesday.

Satellite imagery showed low to medium clouds (partly cloudy) over parts of western Himalayan region, Haryana, West Uttar Pradesh, north Chhattisgarh, Bihar and Arunachal Pradesh.



Forecast valid until Saturday said that isolated rain or snow would occur over Jammu and Kashmir during the next two days and increase thereafter as a fresh western disturbance makes its presence felt. Isolated to scattered rain or thundershowers would occur over Assam and Arunachal Pradesh.

No significant change is expected in minimum temperatures over northwest India. But the maximum temperatures may inch up slightly over northwest and adjoining central India.

Short to medium range forecast until Monday by the IMD suggested that scattered light to moderate rain or snow would occur over Jammu and Kashmir, Himachal Pradesh and Uttarkhand. Isolated to scattered rain or thundershowers are expected to occur over the North-eastern States.