Thiruvananthapuram, Dec. 8
A renewed spell of rain from an approaching easterly wave is likely to induce a positive change in the rainfall profile. Rains are expected to lash coastal Tamil Nadu and, progressively, adjoining Kerala from Sunday onwards.
Northeast monsoon rains are known to occur in spells that last to about three to four days. Spells exceeding four days are much less (20 per cent). There are at times long spells of dry weather with little or no rain.
Meanwhile, night temperatures over the plains of northwest India were near normal on Friday. The current scenario suggests that they are likely to fall during the next 24 hours and increase on Sunday and Monday.
This is due to the approach of a fresh western disturbance, which will cause scattered snowfall over the western Himalayan region. Isolated rain or thundershowers are also likely over the adjoining plains of northwest India.
Dr Akhilesh Gupta of the Department of Science and Technology told
Business Linethat minimum temperatures over the plains (wheat belt) were ranging between 6-12 deg C.
They were 2-4 deg C above normal over northwest India and 4-6 deg C above normal in central India and Uttar Pradesh (another wheat belt).
Maximum temperatures ranged from 18-28 deg C over northwest India and up to 30 deg C over central India and parts of Uttar Pradesh. These were 2-4 deg C below normal in parts of Punjab, Haryana and North Rajasthan; normal in remaining parts of these States; and 2-4 deg C above normal in central India, Uttar Pradesh and Bihar.
Consensus forecasts of various global models for next seven days suggest that minimum temperatures are likely to fall by 2-5 deg C over most parts of northwest India during December 9 to 14 (bringing minimum temperatures to normal) and by 2-4 deg C over central India and Uttar Pradesh during December 11-14 (turning slightly above normal).
No large change is expected in maximum temperatures during this period.
Meanwhile, the Met sub-division of Tamil Nadu and Puducherry has retained a healthy northeast monsoon rainfall record till December 6, with 29 districts out of the total 31 falling under the "excess" or "normal" category. Tirunelveli (+119 per cent); Nilgiris (+87 per cent); and Tuticorin (+84 per cent) topped the `excess' list in further indication that the rainfall was concentrated in the southern districts so far during the season. Perambalur (-26 per cent) and Krishnagiri (-23 per cent) were exceptions, and fell under the deficient category. Negative deviation from the normal has been slowly building in a few others such as Karur, Dharmapuri, Tiruchi, Vellore, and Puducherry.