The Hindu Business Line : Cold wave filters into south peninsula

Thiruvananthapuram, Nov 2 Cold wave conditions have filtered into parts of interior Karnataka signalling little or no presence of seasonally warm easterly to northeasterly flows across the peninsula. This also explains the persisting dry phase in the region.

The flows are now being directed anomalously from the northwest, where the passage of a western disturbance brought in its wake cold and sinking air from across the border (as against the warm, rising and convection-aiding motion in the front of the system).

MAY PERSIST

Cold wave conditions could persist for the next two nights, according to an outlook by the Chennai Met Centre on Sunday. Night temperatures were appreciably to markedly below normal in north coastal Andhra Pradesh, Rayalaseema, north Tamil Nadu and some parts of coastal and north interior Karnataka.

But the northwest could warm up soon in anticipation of another western disturbance, which India Meteorological Department (IMD) traced to over north Pakistan and adjoining Jammu and Kashmir on Sunday.

Night temperatures have been appreciably to markedly above normal in south Haryana, Himachal Pradesh, Rajasthan, northwest Madhya Pradesh, Saurashtra, Kutch and in parts of Bihar, west Uttar Pradesh, Punjab, and above normal in Tripura and in some parts of east Uttar Pradesh and east Madhya Pradesh.

The dry spell in the southern peninsula could continue until November 15, when the causative phase of suppressed rainfall bequeathed by a periodic Madden-Julian Oscillation (MJO) wave gets neutralised ahead of the expected initiation of the cyclical wet phase.

LIKELY WHIRL

In fact, short to medium-term forecasts by the European Centre for Medium-Term Weather Forecasting (ECMWF) suggests the formation of a cyclonic circulation over South Andaman Sea around November 11.

This system is shown to move west and possibly intensify as a ‘low’ over east-central and adjoining southwest Bay of Bengal the next day according to initial conditions recorded on Sunday.

Outlook by the US-based Centre for Ocean-Land-Atmosphere Studies (COLA) too largely supports this scenario through its depiction of a westward-moving regime of reasonably organised rains from wide across the eastern Bay.

During the week ending November 9, COLA shows this corridor narrowing down on its approach to the southeast coast of India where it would dump its moisture mostly over southwest Tamil Nadu and Sri Lanka to its south.

MAY SCALE UP

But the rains are shown to scale up during the week next (November 10-18) by when the MJO ‘neutral’ phase would have established from the equatorial Indian Ocean, Sri Lanka and the extreme south Indian peninsula just to the north.

MJO wave model forecasts show the `neutral’ phase changing over soon to the cyclical wet phase and holding on until December 6.

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