The minimum temperature over the past 24 hours in Delhi dipped to 3.2 degrees Celsius, five degrees below the normal for this time of the year and the lowest so far this winter as recorded at the Safdarjung weather observatory.
On Monday, December 20, 2021, the national capital and its nearby regions are experiencing a cold wave, which took the temperature to below four degrees Celsius for the first time this winter. The India Meteorological Department (IMD) said that though Safdarjung, Delhi’s base station, recorded a temperature of 4.6 degrees on Sunday morning, it plunged to 3.3 degrees at Jafarpur and 3.6 degrees at Lodhi Road. At Palam, the minimum was 5.8 degrees.
What does IMD's yellow alert mean?
IMD issues colour-coded warnings after analyzing the weather forecast data of a particular region over a few days. A yellow alert indicates severely bad weather, which would get worse, causing disruption in day-to-day activities, and asks people in an area to remain vigilant.
The weather forecasting agency has also issued a yellow alert for Uttarakhand till December 21, 2021 in places like Mukteshwar, Mussoorie, Pithoragarh, and New Tehri that have recorded sub-zero or near-freezing temperatures.
Delhi | The minimum temperature is expected to dip to 4 degrees Celcius today as cold wave conditions prevail in the national capital, as per India Meteorological Department (IMD).— ANI (@ANI) December 20, 2021
(Data source: IMD) pic.twitter.com/Hp6LpMmPHe
Cold wave in North India
Meanwhile, IMD has said that several north Indian states such as Himachal Pradesh, Uttarakhand, Haryana, and union territories Delhi and Jammu and Kashmir will witness severe cold wave conditions as the mercury dropped to near freezing temperature.
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A "severe" cold wave is when the minimum temperature dips to two degrees Celsius or the departure from normal is more than 6.4 degrees Celsius.
When the minimum temperature is less than or equal to 10 degrees Celsius and the maximum temperature is at least 4.5 degrees Celsius below the normal, it is said to be a 'cold day'.
Reason for cold wave
IMD said that dry northwesterly winds of about 10-15 kmph and markedly below normal maximum temperatures are causing the adverse impact of cold wave conditions. The dry northwesterly winds are likely to continue to prevail over plains of Northwest India till 21st December, IMD said in a tweet.
TODAY COLD WAVE DETAILS OF NORTH WEST INDIA(Cold wave spell entered today into Day 4-Started since 16-17 Dec night and continuing). Significant improvement from 22 Dec @KumarJenamani @airnewsalerts @DDNewslive @rajeevan61— India Meteorological Department (@Indiametdept) December 20, 2021
IMD predicts cold waves and fog in these states:
States such as Uttarakhand, Punjab, Haryana, Bihar, Uttar Pradesh, Rajasthan, and union territory Delhi will be reporting a big drop in mercury in the coming days as per the IMD predictions.
The weather agency said dense fog is predicted in a few regions of Uttarakhand and Himachal Pradesh during the next three days and Punjab, Assam, Meghalaya, Nagaland, Manipur, Mizoram, and Tripura will also witness dense fog on December 19 and 20.
The IMD has predicted that cold wave to severe cold wave conditions is very likely to continue in northwest India over the next three days.