According to the National Weather Forecasting Centreof the India Meteorological Department (IMD):
Significant Features of past week (10 to 16 December, 2020):
- Two Western Disturbances and their induced cyclonic circulations in quick succession caused fairly widespread to widespread rainfall/snowfall/ thunderstorm activity over Western Himalayan Region and isolated to scattered rainfall/thunderstorm activity over adjoining plains of Northwest India during the 1st half of the week.
- An easterly waves caused scattered to fairly widespread rainfall/thunderstorm activity over Andaman & Nicobar Islands and isolated to scattered rainfall/thunderstorm activity over extreme south Peninsula and Lakshadweep islands during the week.
- Due to trough and wind confluence over central parts of the country, Central India received excess rainfall by 112% above Long Period Average (LPA) during past week.
Forecast for next two week Weather systems & associated Precipitation during Week 1 (17 to 23 December, 2020) and Week 2 (24 to 30 December, 2020) Rainfall for week 1: (17 to 23 December, 2020)
- Under the influence of the easterly wave, scattered to fairly widespread rain/thundershowers very likely over Tamil Nadu, Puducherry &Karaikal, Kerala &Mahe and Lakshadweep area during next 3 days. Isolated heavy to very heavy rainfall very likely over Tamil Nadu, Puducherry &Karaikal on 17th December and isolated heavy falls on 18th & 19th December and over Kerala &Mahe on 18th December and over Lakshadweep on 19th & 20th December, 2020.
- A fresh feeble Western Disturbance is very likely to cause light rain/snow over Western Himalayan region on 20th & 21st December, 2020.
- No significant rainfall likely over remaining parts of the country during the week (Annexure IV).
- Cumulatively, above normal rainfall likely over south peninsula and below normal rain/snow likely over Western Himalayan Region during week 1 (Annexure V).
Rainfall for week 2: (24 to 30 December, 2020)
- Due to the absence of any active Western Disturbance, near normal rain/snow also likely over Western Himalayan Region Under the influence of fresh easterly wave, normal to above normal rainfall activity likely over south peninsula (Annexure V).
Temperature/fog for week 1 & 2: (17 to 30 December, 2020)
- Minimum temperatures are between 2.0°C to 6.0°C over most parts of northwest India. These are markedly below normal (-5.0°C or less) at isolated places over Jammu & Kashmir, Ladakh, Gilgit-Baltistan & Muzaffarabad and Himachal Pradesh; appreciably below normal (-3.1°C to -5.0°C) at a few places over West Rajasthan and West Uttar Pradesh and at isolated places over East Rajasthan, East Uttar Pradesh, Saurashtra & Kutch and Haryana, Chandigarh & Delhi; below normal (-1.6°C to -3.0°C) at a few places over Punjab and Uttarakhand.
No significant change in minimum and maximum temperatures would occur over Northwest India during next 2 days and rise by 2-3°C in minimum temperatures and 5-6°C in maximum temperatures during subsequent 3 days. Fall in minimum temperatures by 3-5°C would occur over East Madhya Pradesh, Vidharbha and Chhattisgarh and by 4-6°C over East India during first half of the 1st week. Fall in minimum temperatures by 2-3°C would occur over West India during next 2 days.
- Overall week as a whole, the minimum temperatures would be below normal by 2-6°C over most parts of northwest, central & east India and near normal or slightly above normal over remaining parts of the country during week 1.
Cold Wave to Severe Cold Wave conditions would occur in some pockets over Punjab, Haryana & Chandigarh, West Uttar Pradesh and north Rajasthan during first half of the 1st week and decrease thereafter.
Cold Day to Severe Cold Day conditions would occur in some to many pockets over Punjab, Haryana, Chandigarh & Delhi, north Rajasthan and northwest Uttar Pradesh during next 2 days and abate tereafter.
- During week 2, there would be slight rise in minimum temperatures as compare to week 1. However, the minimum temperatures would be below normal by 2-4°C over most parts of northwest, central & east India and near normal or slightly above normal over remaining parts of the country (Annexure VI).
There is low probability of cyclogenesis over south Andaman Sea and adjoining southeast Bay of Bengal during first half of week 2.