Heavier rains forecast next week

The Australian Bureau of Meteorology (BoM) has said that the next active phase of the Madden-Julian Oscillation (MJO) wave would develop over West Indian Ocean from early to mid-September.

The MJO wave travels west to east periodically over the Indian Ocean and has been known to have a catalytic impact on prevailing weather over ground, especially during the monsoon.

MONSOON VIGOUR

If the aforementioned scenario were to play out, the BoM expects to see the Indian monsoon getting re-invigorated with increased potential for tropical cyclone development in the region.

The European Centre for Medium-Range Weather Forecasts (ECMWF) tends to support this outlook signalling fresh convergence of flows over the South Peninsula from August 30 (Monday next).

The ECMWF sees the possibility of development of a follow-up low-pressure area (aside of the prevailing one in West-central Bay of Bengal basin) and at least two tropical storms over the Northwest Pacific during this period.

According to the BoM, since May, the MJO wave has displayed generally erratic behaviour, and has had perhaps the greatest influence on weather across southern Asia.

PAK FLOODS

An active burst at the beginning of the month produced heavy rainfall across Pakistan and Afghanistan, which, in association with rare meteorological phenomena on show in the high northern latitudes, triggered devastating floods in the region.

Over the past week, the MJO has begun to progress into the Maritime Continent (Southeast Asian region comprising islands, peninsulas and shallow seas) for the first time since May, and has contributed to the development of a named tropical storm ‘Mindulle' in the South China Sea.

The London-based Tropical Storm Risk Group indicated on Tuesday that the ‘Mindulle' might be approaching Vietnam soon for a landfall.

LIKELY REMNANT

It would now be interesting to watch whether a remnant of the westward-bound storm would set up activity over the North Bay of Bengal.

The seas here have warmed up beyond 30 deg Celsius to being able to sustain a low-pressure area. In fact, the sea-surface temperature (SST) off the Andhra Pradesh coast measured 32 deg Celsius on Tuesday. Meanwhile, a ‘low' has been persisting overnight over the West-central Bay on Tuesday.

According to the Noida-based National Centre for Medium-Range Weather Forecasts (NCMWRF), the ‘low' could persuade the monsoon trough to shift south closer to its normal position during a productive monsoon phase.

This would also mean that the Central and East-central India could be bracing for another active monsoon session over the next two days.

Meanwhile on Tuesday, the Pakistan Met Department issued fresh flood alert for rivers Sutlej and Ravi even as scattered rains have been forecast for the northern provinces from an itinerant westerly trough.

The International Research Institute (IRI) for Climate and Society at Columbia University in updated forecasts based on initial conditions obtaining on Sunday has put the northwestern regions of Pakistan and adjoining India under rain watch during the rest of this week.

Rajasthan, Northwest Madhya Pradesh and parts of Gujarat also are in the list of regions where IRI sees chances for moderate to heavy rain activity.

India Meteorological Department (IMD) said in an update that widespread overnight rainfall was reported from Sub-Himalayan West Bengal and Sikkim.

It was fairly widespread over Uttarkhand, Haryana, Uttar Pradesh, the Northeastern States, Rayalaseema, the West Coast, South Interior Karnataka, North Tamil Nadu and the Andaman and Nicobar Islands.

Satellite pictures showed convective (rain-bearing) clouds over parts of Uttarkhand, Uttar Pradesh, Bihar, Jharkhand, West Bengal, Chhattisgarh, Andhra Pradesh, South Karnataka, Kerala, Tamil Nadu, South and East-central Bay, Andaman Sea and Southeast Arabian Sea.

A warning valid for the next two days said that isolated heavy to very heavy rainfall is likely over Uttarkhand, East Uttar Pradesh, Bihar, Sub-Himalayan West Bengal, Sikkim, Assam, Meghalaya, Arunachal Pradesh, Coastal and South Interior Karnataka, Kerala, Tamil Nadu, Coastal Andhra Pradesh and Andaman and Nicobar Islands.

The IMD forecast signalled isolated heavy to very heavy rainfall on Wednesday for the Jammu Division of Jammu and Kashmir, Himachal Pradesh, Haryana, Chandigarh, Delhi and West Uttar Pradesh.