Main weather producing systems during winters are the Western Disturbances, which move from east to west. In peak winters the WDs induce a low pressure system over south Pakistan and adjoining Rajasthan, which is the case presently.
The system has already caused flooding rains in UAE and south Iran. In last 24 hours, it has affected Afghanistan and Pakistan as well. Dera-Ismail-Khan in Pakistan has received 10 mm of rain, Nokkundi 17 mm and Dalbandi 15 mm.
Now, the weather system has started causing light rain over the western borders of India. And as the system moves across, it will cause moisture incursion from the Arabian Sea, which will lead to clouding and precipitation in Central India.
Besides all these, a confluence zone between winds from the Arabian Sea and Bay of Bengal has formed over Marathwada, Vidarbha and west Madhya Pradesh causing clouding in the region as well. Thus we can draw that it is an unusual cloud pattern over the Indian region.
Normally, a WD produces medium and high clouds over North India and its affect is restricted to northwest India. However, this time around a WD over North Pakistan and Jammu and Kashmir along with its induced system over South Pakistan and adjoining Rajasthan, moisture incursion from Arabian Sea and convergence over Central India has produced multilayered clouding, right from northwest to central India. Some patches of cloud can also be seen over peninsular India.
This clouding will gradually move eastward after causing heavy snowfall in the hills of North India and fairly widespread rain showers along the gangetic plains and Central India.