Mercury continues to plumb lows over North-West India ahead of arrival of fresh western disturbance

Western disturbances moving along Iran-Afghanistan-Pakistan and consummating in alternating cold and wet spells over North-West India are predicted to assume newfound urgency in view of rush of Arctic/polar air farther across the globe over Canada and the US. 

Dangerous cold triggered by a ‘polar vortex’ has already forced inauguration of Trump 2.0 presidency indoors later today. Globe-trotting jet steam transmits wintry weather conditions thousands of kilometres downstream to the east-southeast to a more tropical India in the form of western disturbances.

South Peninsula rain

Meanwhile, enhanced north-easterly winds from Bay of Bengal across Tamil Nadu coast may continue to bring scattered light to moderate rain, thunderstorms and lightning over parts of coastal Tamil Nadu, Puducherry on Monday as well. Satellite maps showed clouds hanging over southern parts of Tamil Nadu across Tirunelveli, Madurai and Pudukottai districts. Much denser clouds waited out over equatorial Indian Ocean and adjoining South-West Bay of Bengal to south-east of Sri Lanka.

Western disturbance train

India Meteorological Department (IMD) said an incoming disturbance in the form of a trough has locked in over central Pakistan. It has spun off an induced cyclonic circulation and sent it in advance West Rajasthan and adjoining Pakistan. A follow-up disturbance as a trough was parked over south-west Iran, bracing to cross into adjoining Afghanistan/Pakistan. 

These systems will trigger isolated to scattered rain/snow over the hills of North-West India (Jammu & Kashmir, Ladakh, Himachal Pradesh and Uttarakhand) till Tuesday and scattered to fairly widespread rain/snow on Wednesday and Thursday; and isolated to scattered rain, thunderstorms and lightning over Punjab, Haryana Chandigarh, Delhi, north Rajasthan and West Uttar Pradesh. 

Lull on Republic Day

After an apparent lull reserved for Republic Day, numerical model predictions suggest a third western disturbance may waft into North-West India the following day. It may unravel itself as a powerful system until it reaches South-West Asia/Middle-East by January 28, but lose much of the sting as it negotiates its onward track towards Iran, Afghanistan and Pakistan. 

Cold Arctic air continued to dominate weather over parts of North-West India on Sunday in the absence of a warmer western disturbance. Minimum (night) temperatures under cloudless skies plumbed to below 0°C over many parts of Jammu, Kashmir & Ladakh. They ranged between 2-5°C over parts of Himachal Pradesh and Punjab; 6-12°C parts of rest of North-West, North-East and Central India; and between 12-16°C over East and West India.