A low-pressure system developing over the Bay of Bengal is expected to intensify into a powerful cyclone, bringing cloudy skies to Nepal from Wednesday and increasing the likelihood of rain from Thursday, according to the Department of Hydrology and Meteorology.
Rojan Lamichhane, a meteorologist at the department, said clouds would begin building on Wednesday, with isolated showers possible in some areas. Some Himalayan locations could also receive snowfall.
“Wednesday is expected to be cloudy, with isolated showers in some places and possible snowfall in parts of the Himalayas,” he said in the department’s weather bulletin on Sunday morning. “The system’s influence will increase on Thursday. From the afternoon, some Himalayan and hilly areas of Koshi, Bagmati and Gandaki provinces could receive rain.”
The system’s effects are expected to be strongest from Thursday night through Friday and into Saturday afternoon, Lamichhane said.
Rain is forecast in Koshi, Madhesh, Bagmati and Gandaki provinces, as well as the eastern parts of Lumbini province. The impact is expected to be weaker farther west.
With the paddy harvest under way and the trekking and mountaineering season in progress, Lamichhane urged farmers and travellers to take precautions.
“Those planning to go trekking should remain alert. Trekkers and tourists in Himalayan districts need to exercise caution during this period,” he said. “Those already on the trails should move to safe locations. Since the effects are expected to be greater from Thursday to Saturday, farmers would be better off bringing in their paddy before then or waiting until the adverse weather has passed.”
Meteorologist Binod Pokharel also said several weather models were indicating a similar likelihood of rain. In an analysis shared on social media, he warned that the risk of rainfall would be comparatively high from Thursday through Saturday, including in Kathmandu and several districts across Koshi, Madhesh, Bagmati, Gandaki and Lumbini provinces.
“Clouds will begin building from Wednesday, but heavy rain is possible in most places from Thursday,” Pokharel said in a video posted on social media. While the impact is expected to be weaker in Sudurpashchim and Karnali provinces, heavy rain is possible from eastern Lumbini to Koshi province, he said.
Pokharel’s analysis identified 29 districts across five provinces as potentially at risk.
He said rainfall could intensify if the low-pressure system from the Bay of Bengal interacts with an upper-level trough as it approaches Nepal. Such conditions could damage ripe paddy still standing in fields as well as harvested crops left out to dry. He urged farmers to prepare in advance.
David Dhakal, another meteorologist at the department, said the system developing over the Bay of Bengal would also influence Nepal’s weather. Its effects could initially be felt around Koshi, Madhesh, Bagmati and Gandaki provinces before spreading farther west, he said. However, the amount of rainfall and the level of risk could not yet be determined with certainty.
According to the India Meteorological Department, the low-pressure system formed over the east-central Bay of Bengal and the adjoining south-eastern region is gradually strengthening. It was forecast to intensify into a deep depression on Sunday and develop into a cyclone over the west-central Bay of Bengal by Monday morning.
The system is expected to strengthen further as it moves west-north-west, reaching waters near the Andhra Pradesh coast by Wednesday morning. It is forecast to move towards the coast of northern Andhra Pradesh and adjoining southern Odisha.
Nepal’s monsoon officially withdrew from the country on October 14. The weather had since cleared across much of Nepal, but the developing system in the Bay of Bengal has raised the prospect of another spell of rain and snowfall.
