From red to orange: What do IMD's colour-coded weather alerts mean?

As the monsoon is wreaking havoc in various parts of India, let us have a look at the colour-coded weather warnings issued by the IMD

The India Meteorological Department (IMD) often issues colour-coded alerts to keep people informed of upcoming weather events and their severity. These alerts are issued in the event of inclement weather conditions such as rain, snowfall, thunderstorms, squalls, hailstorms, dust storms, and even heat waves and cold waves.

Certain parameters determine when these colour codes will be issued. Green, Yellow, Orange, and Red are the four colour codes. The assessment is based on the likelihood of an event occurring and for an impact-based warning valid for a maximum of five days.

How are weather alerts issued?

When it comes to rainfall alerts, the Green code denotes less than 64 mm of rain in 24 hours. A yellow alert is issued if the expected rainfall ranges between 64.5 mm and 115. 5 mm.

An orange alert is issued when rainfall totals between 115.6 and 204.4 mm in a single day, while a red alert is issued when rainfall totals exceed 204.5 mm in a 24-hour period.

These alerts are primarily for the people who live in the affected areas and how they should react in that specific situation.

While wind speed determines the alert issued during thunderstorms, visibility range becomes the deciding factor during foggy conditions.

In the case of a dust storm, both wind speed and visibility are taken into account when issuing an alert.

What do these colour codes mean?

Green - No advisory

A green alert indicates that, while a weather event is possible, no advisory is required.

Yellow - Be aware
 

A yellow alert denotes bad weather conditions and the possibility that the conditions will worsen, causing disruptions to daily life.

Orange - Prepare
 

When extremely bad weather is forecast, an orange alert is issued to warn of potential disruptions to transport, rail, road, and air. Power outages are also likely.

Red- Take action
 

A red alert is issued when an extremely bad weather condition is expected to disrupt transportation and power supply. It might also pose a risk to life.