Westerly wind delays onset of monsoon

Kathmandu, June 10

Despite prediction of early monsoon onset by meteorologists, Nepal has witnessed yet another delayed monsoon. Meteorological Forecasting Division informed today that monsoon was blocked by westerly wind that is occupying most parts of the country.

According to MFD, apart from the eastern region, all regions of country have been strongly affected by westerly wind. Meteorologist at the MFD Barun Paudel said westerly wind has prevented monsoon from spreading across the country.

“As westerly wind occupies most parts of country, spread of monsoon has been delayed although easterly wind has already hit the eastern region,” Paudel told The Himalayan Times, adding, “Until the westerly wind is replaced by easterly wind, monsoon cannot spread throughout the country.”

It is reported that monsoon has already hit Bhutan and Andhra Pradesh of India. “If there is a dramatic change, monsoon may start within two days, but if the westerly wind persists it may take a few more days for monsoon to begin in Nepal,” said Paudel.

Earlier last week, Department of Hydrology and Meteorology has predicted the possibility of early monsoon onset in Nepal.

MFD said the earlier prediction failed due to the effects of westerly wind. In Nepal, monsoon generally begins on June 10 and withdraws from Nepal on September 23.

Director General at MFD Dr Rishi Ram Sharma said two major conditions play vital role in the entry of monsoon to Nepal as westerly winds should be replaced by easterly (monsoon) winds and significant rainfall should be recorded.

According to MFD, after monsoon missed it deadline today it is recorded as the 34th delayed monsoon in 49 years so far. Existing data shows that monsoon started on the usual date just three times  — in 1971, 1994, and 2008.

Last year Monsoon  entered Nepal on June 15. Once monsoon enters from the eastern region, it makes progressive westward advancement to the remaining parts of the country over the next few days through the central region.

Meteorologists said conditions looked favorable for arrival of monsoon before the scheduled date. Monsoon lasts for an average of 105 days.

Nepal receives an average of 80 per cent of annual rainfall during the monsoon, originating in the Bay of Bengal and moves along the southern flanks of the Himalayas, bringing rains to Nepal. The average annual rainfall in Nepal is 1,600 mm, but it varies from place to place depending on climatic conditions.