The meteorological department on Friday sounded a cold-wave alert for isolated pockets of Jharkhand in the next 24 hours as the mercury plunged further across the state, pushing night readings down four to five notches below normal.

According to India Meteorological Department (IMD) guidelines, a cold wave is declared when the minimum temperature is 5° to 6°C less than the normal if the normal minimum temperature of the place is equal to 10°C or more, or when the departure from normal is 4° to 5°C when the normal minimum temperature of the place is less than 10°C.

Several places including Ranchi, Jamshedpur, Daltonganj, Bokaro, Giridih, Chaibasa (in West Singhbhum), Dumka and its adjoining districts in Santhal Pargana region experienced the coldest day of this winter season on Friday.

Kanke, the state’s cold cauldron, recorded a minimum of 5.7°C on Friday, the season's lowest. Barely 10km from the capital, Kanke had touched freezing point in 2010 and in 2018.

State capital Ranchi recorded 6.4°C on Friday against Thursday’s 6.6°C.

Friday’s reading in Ranchi was three notches below normal.

In Jamshedpur, the minimum reading dropped to 9.5°C — the season's lowest — from 10.2°C 24 hours ago. Friday’s reading was two notches below normal.

Daltonganj, the Palamau district headquarters, recorded the season's coldest day with the minimum plummeting to 7.9°C, two notches below normal. On Thursday, Daltonganj had notched 8.6°C.

Bokaro and its adjoining districts saw plummeting temperatures. The local observatory in Bokaro on Friday recorded a minimum of 6.6°C, the season’s lowest, against Thursday’s 9.1°C. Friday’s minimum reading in Bokaro was five notches below normal.

In Dumka, the minimum reading plunged to 6.8°C as compared to Thursday’s 7.9°C. Friday’s reading in Dumka was four notches below normal. Several other districts in Santhal Pargana recorded the season’s coldest day so far. Chaibasa in West Singhbhum district also saw plummeting night readings. The local observatory in the West Singhbhum district headquarters nosedived to 7.8°C from Thursday’s 8.6°C. Friday’s minimum in Chaibasa was four notches below normal.

Weathermen attributed the plummeting temperatures in Jharkhand to the free flow of the icy north-westerly wind.

“Free flow of north-westerly winds coupled with snowfall in the northern parts of the country is resulting in abrupt fall in night readings in Jharkhand,” said Abhishek Anand, a senior scientist at the IMD’s Ranchi centre. “The moisture content is also very less in the atmosphere. Dry weather condition is expected to prevail over the state in the next two to three days. Minimum readings are low and are expected to fall by another one or two degrees.”

A forecast issued by the Ranchi Met Centre predicted cold-wave conditions at isolated pockets in western and northern parts of Jharkhand. A warning of dense fog was also issued for northern districts of Jharkhand in the next 48 hours.

Weathermen at the Regional Meteorological Centre in Alipore, Calcutta, also said the north-westerlies were pulling the mercury down.

“The chill has intensified due to cold and dry north-westerly wind,” said a duty officer. “The cold wave prevailing in large parts of northern India is also impacting Jharkhand’s weather.”