IMD raises potency of westerly couple to ‘active'

India Meteorological Department (IMD) has raised to ‘active' status the westerly couple affecting the western Himalayan region one after the other.

‘Active' western disturbances are also known to roll strings of thundershowers down the hills and into the plains, including Punjab, Haryana and west Uttar Pradesh.

Earlier last week, the European Centre for Medium-Range Weather Forecasts (ECMWF) had hinted raised level of activity over northwest India from early this week.

Widespread rain

Forecast until Wednesday spoke about the possibility of widespread rain or snow over Jammu and Kashmir and Himachal Pradesh. It would be fairly widespread over Uttarakhand on Sunday and Monday and decrease thereafter.

Scattered rain or thundershowers would occur over Punjab, north Rajasthan, Haryana, Delhi and west Uttar Pradesh during this period before relenting.

The IMD also sees fall in day temperatures by 2 to 3 degree Celsius from their current highs as the westerly system moves away into the east.

But no significant change is seen in night temperatures over northwest and adjoining central India, given that a follow-up system may be drifting in with the entourage of cloud formations.

May last long

Meanwhile, the ongoing wet session for northwest India may last until February 22, according to short-to-medium outlook by the US National Centres for Environmental Prediction and the ECMWF.

In particular, the week ending February 22 would see rains of varying spells in east India, northeast India and even the coastal regions of West Bengal, Orissa and even parts of Andhra Pradesh.

A concurrent build-up over southern peninsular India oriented to the east would mean that an incoming Bay of Bengal circulation could set up a union with westerlies originating from the opposite direction.

Southern rains

The ensuing rains show a bias to spread along the southeast coast as per forecasts, but mainly along the Andhra Pradesh coast and further north as mentioned earlier.

The southern peninsula also should see some isolated to scattered rain in the bargain, according to the forecasts.

Southwest Bay of Bengal also featured banks of rain clouds as easterly wave activity built up with a core rain belt still targeting Sri Lanka.

Indications are that a low-pressure area may spring up from the churn, but take a south-southwest turn away from southern Tamil Nadu coast to drift towards the Sri Lanka coast.

Repeat circulation

Going forward, this would leave the southwest Bay waters free to whip up a repeat circulation, though it is not shown as building up significantly in strength.

Activity in the neighbourhood waters may spark off some rain over southern Tamil Nadu and adjoining Kerala, the IMD said in its morning outlook on Sunday.

The northeast monsoon activity is far from over around the equatorial latitudes with Sri Lanka caught in the eye most of the time; the stamp of a prevailing La Nina event in the east Pacific is built around it.