Punjab, Haryana, Delhi and parts of Uttar Pradesh are likely to have moderate fog from December 29 till December 31. Indian Meteorological Department (IMD) chief Bhuken Lal told The Tribune today that all IMD models and synoptic situations suggested that the western disturbances to hit the region in the first week of January was likely to bring in the much-required rain to the northern plains on January 1 and 2.
In fact, it has been a rather no-rain situation in December in the plains of the North. All recent spells of western disturbances in the region since December 21, when fog first hit the northern plains, including the current one hovering over the region, have been giving snow and rain to the upper reaches and fog to the plains.
Dr Lal says all three western disturbances since December 21 have been small circulations in the lower layer of the atmosphere with hardly any support from the upper levels. Meaning that there has been no continuity between the inflow below and the outflow above due to which the plains are receiving medium to light clouding but no rain. In any case, even fog is nothing but clouds at the ground level.
However, since December 21 all conditions are favourable for fog to set in, including low temperatures, sufficient humidity and low wind speed, which is why during last week, heavy fog engulfed the plains that disrupted air and rail traffic in the region.
These spells of western disturbances also caused rain and snow in some upper reaches of Jammu and Kashmir, Himachal Pradesh and parts of Uttaranchal. Dr Lal says the current western disturbance is likely to behave in a similar way, bringing in snow and rain to the upper reaches and medium to light fog to the plains after it moves away the day after tomorrow. However, the next western disturbance will be different and will bring rain to the plains.
Incidentally, the fog that created chaos and confusion last week has not been as bad as it was in December 2003. In fact, this year the IMD is not expecting the situation to be so bad.
Dr Lal clarifies that the passage of the western disturbances is not well-defined. At times, they come in succession and at times they are well-spaced. Meaning, that Met predictions can never be 100 per cent accurate.
