Cloudbursts triggered flash floods in Jammu and
Kashmir’s Amarnath shrine on Friday, claiming at least five lives, officials said. 

What are cloudbursts?

A cloudburst is a sudden aggressive rainstorm falling for a short period of
time limited to a small geographical area. If 10 centimetres of rainfall is
received at a station within one hour, the rain event is called a ‘cloudburst’.
This sudden discharge of a large amount of water often causes loss of human lives
and property.

How do cloudbursts occur?

When warm monsoon winds interact with cold winds it leads to formation of
huge clouds, according to India Meteorological Department (IMD) Director
Mrutunjay Mohapatra.

Such clouds are called cumulonimbus and can stretch to 13–14 kilometres in
height. If they get trapped over a region or if there is no air movement for
them to disperse, they discharge over a specific area.  

Where do cloudbursts occur?

Cloudbursts usually occur in high-altitude areas due to formation of a
low-pressure area on the top of a mountain. The low-pressure zone attracts
clouds to the top of the mountain with immense force. When they hit the peak,
the moisture is released in the form of rain.

In case of some cloudbursts, almost 13 centimetres of rain can fall in an
hour, often in the form of extremely large droplets.

IMD Director Mohapatra says a cloudburst is a very small-scale event and
mostly occurs over hilly areas in the Himalayas or the Western Ghats.

Why are cloudbursts difficult to predict?

According to IMD’s official website, cloudbursts are very difficult to predict
due to their small scale in space and time. Monitoring or nowcasting (that is,
forecasting few hours ahead of time) requires a dense radar network over
cloudburst-prone areas a very high-resolution weather forecasting model to
resolve the scale of a cloudburst.