Weekly Tropical Climate Note

Northern hemisphere monsoons to remain active

The Indian and Asian southwest monsoons remain active and are expected to generate further widespread, heavy rainfall across a region extending from northeastern India, through Bangladesh and into Nepal. Regular, daily rainfall totals between 100 and 200 mm have been a feature across many sites in this region during the past week. The heavy rainfall caused widespread flooding and significant landslide activity.

However, to the south of the heavy rain zone, parts of northwest India, including India's capital city Delhi, are experiencing sweltering heatwaves. This heat is a combination of the high humidity in the region, and being far enough away from the monsoon trough that deep cloud and rain has not occurred. Daytime maximum temperatures between 35 and 40 °C, combined with high humidity, have been observed in recent days and are expected to continue for the coming days.

Further east, the near-stationary Mei-yu (Baiu) front remains very active and has continued to produce widespread, heavy rain over eastern China. The torrential rain brought significant flooding.

Tropical weather enhanced away from Australia

Tropical depression Falcon, named by the Philippines meteorological agency, lies to the east of the Philippines and is expected to reach tropical cyclone strength in the next 24 to 48 hours. The current forecast track indicates a high chance of this system passing close to Luzon in the northern Philippines.

For tropical cyclone information in this region refer to the Japan Meteorological Agency or PAGASA, the Philippines agency.

While the Madden–Julian Oscillation (MJO) became weak or indiscernible in recent days, the influence of an equatorial Rossby wave enhanced tropical weather across parts of the central and western Pacific Ocean. The westwards-moving Rossby wave facilitated the development of a pair of tropical lows in the central Pacific Ocean last week, and the associated low-pressure troughs extended further west across both the North and South Pacific regions. In the past few days, cloud and rainfall in the southern hemisphere dissipated as the Rossby wave weakened, but satellite imagery clearly shows a broad region of deep cloud persisting over the western North Pacific Ocean. 

International climate models show two different forecast scenarios for the MJO: about half of the surveyed models predict it will remain weak or indiscernible for the next week to fortnight, while the remaining models predict the signal will develop and strengthen over the Indian Ocean in the coming days.

In either scenario, the MJO is unlikely to lead to above-average rainfall to the north of Australia. The weather systems associated with the equatorial Rossby wave are expected to remain the primary broadscale features modulating rainfall to Australia's north in the coming week.

Read more about the Bureau's MJO monitoring.

Product code: IDCKGEW000

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