With the passage of the Western Disturbance (WD) and setting in of the northerly winds, many places in North India witnessed a significant fall in night temperatures leading to a cold Tuesday morning. But our weather experts at Skymet say that this fall in night temperatures is usual for this time of the year and the minimums which were above normal by 4 to 5 degrees are coming back to normal.
They explain that for a cold wave condition, the minimum temperature should at least be 5 degrees below average. For instance, Narnaul in Haryana was the coldest in North India with minimum recording 3.3 degrees on Tuesday morning. But cold wave conditions still have not developed as the average minimum temperature is 6.3 degrees for the month. Hisar and Karnal were two other places in Haryana where night temperatures were below normal at 4.6 and 6.8 degrees respectively.
Amritsar in Punjab recorded a minimum of 4.2 degrees which is normal for the month of December. The temperature may be too low for the plains but for a cold wave conditions to develop, it should be below average by 5 degrees or so.
Another Western Disturbance (possibly by 26th of December) could pull these temperature down by about 5 degrees to bring a cold wave and aggravate winter in India. Icy winds originating from the snowy region of Jammu & Kashmir are helpful in bringing down the night temperatures in India.