Threat of ‘very dense fog’ (visibility of 50 metres or less) grounding aircraft and other modes of traffic loomed large over North-West and parts of eastern region.
The outlook is valid for at least two days over parts of Punjab, Haryana, Delhi, Uttar Pradesh, Bihar and northern parts of West Bengal.
WESTERN DISTURBANCE
This is in view of arrival of a fresh western disturbance from Thursday even as a feeble one waited its turn to move out and away from Jammu and Kashmir.
Till such as the comparatively warmer air associated with the fresh westerly engulfs it, ‘cold day’ would prevail over many parts of North-West for the next two days.
This is because the cloudless skies allow cold Arctic air wafting from across the border to ‘sink in’ over the plains, increasing its bite.
Cloud/fog associated with western disturbance prevent this ‘sinking motion’ to some extent and prevents terrestrial radiation from escaping the surface.
An India Meteorological Department (IMD) update said that fog to dense fog conditions would occur over Punjab, Haryana, Delhi, North Rajasthan, Uttar Pradesh, Bihar, north Madhya Pradesh, West Bengal and Assam during the next three days.
MERCURY UPTICK
It also indicated slight rise in minimum temperatures (as explained above) over Indo-Gangetic plains during this period.
But a fall in maximum temperatures has been indicated for over east Uttar Pradesh and Bihar during the next two days (so long as the clouding does not reach them).
Light rain or snow has been forecast over Jammu and Kashmir, Himachal Pradesh and Uttarakhand on Wednesday.
In the South, the trough of lower pressure extending from Comorin to North Maharashtra coast has moved away westwards (out into Arabian Sea).
EASTERLY WAVE
A fresh trough associated with a building easterly wave has advanced into Southeast Bay of Bengal (from Andaman Sea).
An IMD outlook for next two days said rain or thundershowers are likely at one or two places over Tamil Nadu, Kerala and Lakshadweep.
Thundershowers are also likely over Vidarbha, east Madhya Pradesh, Chhattisgarh and Odisha from moisture mopped up by winds from the Arabian Sea trough.
An extended outlook valid until Tuesday next spoke about the possibility of an Increase in rainfall activity over south peninsular India.