From its perch across the north-west border, the prevailing western disturbance has lobbed in the weather-maker cyclonic circulation into west Rajasthan overnight on Thursday. As if on cue, rain and snow broke out at many places over Jammu and Kashmir and Himachal Pradesh and at one or two places over Uttarakhand during the 24 hours ending in the morning.
DENSE FOG
In the plains, the westerly system triggered dense to very dense fog over many parts of Uttar Pradesh, Haryana and Delhi as also parts of Bihar, Punjab and sub-Himalayan West Bengal.
India Meteorological Department (IMD) expected these conditions to continue on Thursday and also into the weekend in these regions. Visibility would reduce to 100 meters or less in dense to very dense fog in the morning hours over Punjab, Haryana, Delhi and north Rajasthan on Friday. However, Uttar Pradesh, Bihar and sub-Himalayan West Bengal would likely see the fog cover hang over until Sunday, the IMD said.
HEAVY RAIN
Heavy rain or snowfall has also been forecast at a few places over Jammu and Kashmir and at one or two places over Himachal Pradesh.
A short-term outlook until Sunday said that minimum temperature would rise by 2 to 3 deg Celsius over parts of north-west and adjoining central India thanks to the warming influence of the prevailing westerly. Rain or thundershowers are likely at one or two places over Punjab and Rajasthan during next two days and increase thereafter. Rain or thundershowers may also be unleashed over Delhi, Uttar Pradesh, north Madhya Pradesh on Friday and at a few places thereafter.
NEXT WESTERLY
An extended outlook valid until Tuesday spoke about the possibility of rain or snow at a few places over the western Himalayan region.
Rain or thundershowers could break out over plains of northwest India, the Northeastern States, east and extreme south peninsular India.
Night temperatures could fall by 2 to 4 deg Celsius over many parts of north-west and adjoining central India as the prevailing westerly system exits the region, exposing the frigid tail. This could lead to development of ground frost and cold wave. According to global models, a moderately strong successor westerly system is expected in by Thursday (December 12). This could once again bring in some warmth, and along with it snow for the hilly regions and rains for the plains of northwest India.