ISLAMABAD: Cloudbursts are causing chaos in mountainous parts of India and Pakistan, with tremendous amounts of rain falling in a short period of time over a concentrated area. The intense, sudden deluges have proved fatal in both countries.

As many as 300 people died in one northwestern Pakistani district, Buner, after a cloudburst. The strength and volume of rain triggered flash flooding, landslides and mudflows. Boulders from steep slopes came crashing down with the water to flatten homes and reduce villages to rubble.

The northern Indian state of Uttarakhand had a cloudburst earlier this month. Local TV showed floodwaters surging down a mountain and crashing into Dharali, a Himalayan village. In 2013, more than 6,000 people died and 4,500 villages were affected when a similar cloudburst struck the state.

They are complex and extreme weather events.

A cloudburst occurs when a large volume of rain falls in a very short period, usually more than 100 millimeters (about 4 inches) within an hour over a localized area, around 30 square kilometers (11.6 square miles).