Delhi, which witnessed the hottest April in 12 years, was on orange alert yesterday. Today, the capital has been downgraded to yellow. We take a look at the weather warnings that come with IMD’s colour codes
A yellow warning has been issued for Delhi for three days until 1 May. AFP
India is in the grip of a searing heatwave and it’s only going to intensify in the coming days. Northwest and central India are likely to witness heatwave conditions over the next five days; in the east, the extreme temperatures will persist for two days.
According to experts quoted by PTI, mercury may even rise to 47 degrees Celsius in parts of northwest India. Delhi, which witnessed the hottest April 12 months on Thursday, was on an orange watch but is now downgraded to yellow. An orange alert had also been issued for Rajasthan, Madhya Pradesh, and Maharashtra’s Vidarbha region.
What are these colour codes that the Indian Meteorological Department issues and what do they mean?
Why colours are used to warn of disasters?
According to the Indian Meteorological Department (IMD), colour codes are used in weather warnings to emphasise the severity of the situation at hand. The idea is to forewarn relevant officials and the disaster management authorities about the impact of the weather conditions and help them prepare for necessary action related to disaster risk reduction.
What are the colours used and what do they stand for?
Four colours are used to sound a warning: green, yellow, orange and red. Each has its own meaning and comes with a set of protocols. The warnings are updated on daily basis.
Green means all is well and no advisory is issued. This means there’s no unusual change in the weather.
Yellow indicates that authorities should be aware. In such a situation one can expect severely bad weather that spans over days. It also suggests that the weather could change for the worse, disrupting day-to-day activities. A yellow warning has been issued for the next three days for Delhi, Punjab, Haryana, Jharkhand, and western Uttar Pradesh.
Orange or amber is a “be prepared” warning. It’s a caution against extremely bad weather with the potential of disruption in commute with road and rail closures and interruption of power supply.
Delhi, which was on the orange watch, recorded a maximum temperature of 43.5 degrees Celsius on Thursday. The city has recorded nine heatwave days in April, the highest since 11 such days witnessed in the month in 2010.
Colours and the disruption in daily life
Delhi and Rajasthan are on the brink of a power outage.
The ruling Aam Aadmi Party government has expressed its concern over the possible shortage of coal in power plants that supply electricity to the national capital. The National Thermal Power Corporation (NTPC)’s Dadri-II plant has only a day’s worth of coal and in Jhajjar (Aravalli), only seven to eight days of coal is left.
In Rajasthan, the electricity demand has increased 31 per cent, leading to power cuts that last a gruelling five to seven hours a day.
In Madhya Pradesh, mercury has maintained an upward trend with temperatures crossing 45 degrees Celsius. And Vidarbha in Maharashtra has consistently reported maximum temperatures in the range of 40 degrees Celsius to 45 degrees Celsius for the past two months.
During an orange alert, the IMD advises avoiding exposure to heat, keeping hydrated by drinking sufficient water even if not thirsty, and drinking ORS, lassi, rice water, and buttermilk to prevent dehydration.
When on the red watch
The red alert urges authorities to swing into action. It means the weather is extremely bad and is likely to cause a shutdown of road and rail, interrupt power supply, throwing life out of gear.
During a red alert issued last year in Delhi in May, IMD advised residents not to step out of their houses between 1 pm to 5 pm.
How are the colour codes decided?
The IMD says that the decision to assign a colour to a weather situation is taken under a five-day forecast scheme. A specific matrix is followed, “giving thrust on the probability of occurrence of the event as well as its impact assessment”.
The assessment regarding the colour code for “impact-based warning”, includes meteorological factors, hydrological factors, geophysical factors, etc, “which may interact with each other to determine the impact and risk”, according to the weather office. It takes into account all these factors to decide the appropriate colour code for warning for a state or a region.
The IMD points out that even though colour code criteria used by all the centres are the same, the colour code used for subdivisional warning doesn’t need to be the same as the colour code used for any district in that subdivision. That’s because while the criteria laid out are general, the weather activity and impact may be different depending on the location.
Are colour codes only used for heatwaves?
Colour warnings are used for all weather conditions including rainfall, thunderstorms, lightning, and snow.
With inputs from agencies
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