emergency manager1 December 2017
Seasonal Outlook for the Temperatures during December 2017 to February 2018
Background
The country experiences cold weather primarily during December to February. During this season, many parts of the country experience cold wave conditions (days with abnormally cooler temperatures) with many adverse consequences. Abnormally below normal temperatures can have devastating effects on human health, water supply and power generation and outage. On an average about 780 deaths particularly of homeless people take place due to cold waves during each year. The country averaged seasonal mean temperatures during the 2016/17 winter season (December to February) with anomaly of +1.0 0C was the fourth warmest ever winter season since 1901 with most parts of the country recording warmer temperature anomalies as per the India Meteorological Department (IMD) forecast issued in November, 2017.
The country averaged pre-monsoon season (March-May) mean temperature was also warmer than normal with anomaly of +0.770C, which (along with 2010) was the sixth warmest ever spring season since 1901. Warmer than normal winter and spring seasons also resulted in the country averaged temperatures over the period January to October to be warmer than normal in line with the warmer than normal global climate observed during the period.
The annual mean land surface air temperature averaged over the country during 2017 till October is +0.730C above the 1971-2000 average. Analysis of minimum temperature data over the country during the last four decades suggests decreasing trends in the frequency and duration of cold waves in many parts of the country in tune with the decreasing trends in cold waves observed over many other parts of the world.
One of the reasons behind the decreasing trend in the cold waves is the global warming. However, the ocean conditions over the equatorial Indian and Pacific oceans also contribute to the year to year variability of cold waves over the country. Since 2016, IMD has been issuing seasonal outlook for the subdivision temperatures over country for both hot and cold weather seasons. IMD has now prepared a seasonal outlook for the 2017/2018 winter season (December to February) temperatures over the country.
Highlights of Forecast
Country averaged mean land surface air temperature during 2017 till October was significantly above normal (0.730C from 1971-2000 normal).
During the December 2017 to February 2018 season, warmer than normal maximum and minimum temperatures are likely in most of the meteorological sub-divisions of the country with warmest temperature anomalies likely in subdivisions of north and northwest India. However, season mean temperatures in most of the subdivisions are likely to be cooler than last year.
Normal to below normal cold wave (CW) conditions are likely over core cold weather zone.
Forecast for the DJF Season (December 2017 to February 2018)
The forecast indicates above normal maximum temperatures in all subdivisions except Rayalaseema and Kerala, and above normal minimum and mean temperatures in all the subdivisions. The season averaged maximum temperatures are likely to be warmer than normal by ≥1°C in west Rajasthan, Haryana, Chandīgarh & Delhi, and Jammu & Kashmir and by 0.5oC to 1 oC in Himachal Pradesh, Uttrakhand, Punjab, east Rajasthan, west and east Uttar Pradesh, Gujarat, Saurashtra & Kutch, Madhya Maharashtra, Marathawada, Vidharbha , west and east Madhya Pradesh, Arunachal Pradesh, Assam & Meghalaya and Nagaland, Manipur, Mizoram, Tripura (NMMT).
Rest of the subdivisions are likely to experience maximum temperature anomalies of <0.5oC. Two subdivisions (Rayalaseema and Kerala) are likely to experience slightly cooler than normal temperatures (<-0.5 oC). The season averaged minimum temperatures are likely to be warmer than normal by ≥1°C in Gujarat region and by <0.5oC in Punjab and two subdivisions of West Bengal. The remaining subdivisions are likely to experience warmer than normal minimum temperatures of 0.50C to 1 0C.
The season averaged mean temperature are likely to be warmer than normal by 0.50C to 1 0C in all the subdivisions of the entire country except Konkan and Goa, Karnataka, Kerala, Tamil Nadu, Rayalaseema and two subdivisions of West Bengal (in which mean temperatures are likely to be cooler than normal by 0.5oC). There is moderate (40%) probability of minimum temperatures in the core CW zone during the 2017/18 DJF season to be above normal.
Core CW zone covers states of Punjab, Himachal Pradesh, Uttarakhand, Delhi, Haryana, Jammu & Kashmir, Rajasthan, Uttar Pradesh, Gujarat, Madhya Pradesh, Chhattisgarh, Bihar, Jharkhand, West Bengal, Odisha and Telangana and met subdivisions of Marathwada, Vidharbha , Sourashtra and Madhya Maharashtra. This suggests occurrence of cold wave conditions in the core CW zone during the 2017/18 cold weather season is likely to be normal to less than normal.
The Monsoon Mission Climate Forecast System (MMCFS)
The present temperature outlook was prepared using MMCFS. The MMCFS has been used to prepare forecasts for the monsoon rainfall since 2012. MMCFS model developed by Indian Institute of Tropical Meteorology (IITM), Pune during the Monsoon Mission Phase was implemented and run operationally at the office of Climate Research and Services (CRS), IMD, Pune from January, 2017.
The MMCFS has a spatial resolution of about 38 km and improved modules of model physics. The model hindcasts and forecasts were bias corrected using data for the period 27 years (1982-2008). The seasonal temperature forecast outlook for the December 2017 to February 2018 was prepared based on the 2017 November initial conditions. The forecast was prepared using 31 ensemble member forecasts. The model showed moderate skill over many subdivisions over northwest and central India during the period 1982-2008. 4. ENSO conditions in the Pacific Ocean Currently, the SST conditions over equatorial Pacific suggest weak La Nina conditions. Atmospheric conditions are also indicating La Nina conditions.
The latest forecasts from MMCFS indicate strong probability for current La Nina conditions to persist at least till the winter season (DJF). Historical data indicates weak or no consistent association between La Nina and winter temperatures over India.
emergency manager1 December 2017
Seasonal Outlook for the Temperatures during December 2017 to February 2018
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Background
The country experiences cold weather primarily during December to February. During this season, many parts of the country experience cold wave conditions (days with abnormally cooler temperatures) with many adverse consequences. Abnormally below normal temperatures can have devastating effects on human health, water supply and power generation and outage. On an average about 780 deaths particularly of homeless people take place due to cold waves during each year. The country averaged seasonal mean temperatures during the 2016/17 winter season (December to February) with anomaly of +1.0 0C was the fourth warmest ever winter season since 1901 with most parts of the country recording warmer temperature anomalies as per the India Meteorological Department (IMD) forecast issued in November, 2017.
The country averaged pre-monsoon season (March-May) mean temperature was also warmer than normal with anomaly of +0.770C, which (along with 2010) was the sixth warmest ever spring season since 1901. Warmer than normal winter and spring seasons also resulted in the country averaged temperatures over the period January to October to be warmer than normal in line with the warmer than normal global climate observed during the period.
The annual mean land surface air temperature averaged over the country during 2017 till October is +0.730C above the 1971-2000 average. Analysis of minimum temperature data over the country during the last four decades suggests decreasing trends in the frequency and duration of cold waves in many parts of the country in tune with the decreasing trends in cold waves observed over many other parts of the world.
One of the reasons behind the decreasing trend in the cold waves is the global warming. However, the ocean conditions over the equatorial Indian and Pacific oceans also contribute to the year to year variability of cold waves over the country. Since 2016, IMD has been issuing seasonal outlook for the subdivision temperatures over country for both hot and cold weather seasons. IMD has now prepared a seasonal outlook for the 2017/2018 winter season (December to February) temperatures over the country.
Highlights of Forecast
Country averaged mean land surface air temperature during 2017 till October was significantly above normal (0.730C from 1971-2000 normal).
During the December 2017 to February 2018 season, warmer than normal maximum and minimum temperatures are likely in most of the meteorological sub-divisions of the country with warmest temperature anomalies likely in subdivisions of north and northwest India. However, season mean temperatures in most of the subdivisions are likely to be cooler than last year.
Normal to below normal cold wave (CW) conditions are likely over core cold weather zone.
Forecast for the DJF Season (December 2017 to February 2018)
The forecast indicates above normal maximum temperatures in all subdivisions except Rayalaseema and Kerala, and above normal minimum and mean temperatures in all the subdivisions. The season averaged maximum temperatures are likely to be warmer than normal by ≥1°C in west Rajasthan, Haryana, Chandīgarh & Delhi, and Jammu & Kashmir and by 0.5oC to 1 oC in Himachal Pradesh, Uttrakhand, Punjab, east Rajasthan, west and east Uttar Pradesh, Gujarat, Saurashtra & Kutch, Madhya Maharashtra, Marathawada, Vidharbha , west and east Madhya Pradesh, Arunachal Pradesh, Assam & Meghalaya and Nagaland, Manipur, Mizoram, Tripura (NMMT).
Rest of the subdivisions are likely to experience maximum temperature anomalies of <0.5oC. Two subdivisions (Rayalaseema and Kerala) are likely to experience slightly cooler than normal temperatures (<-0.5 oC). The season averaged minimum temperatures are likely to be warmer than normal by ≥1°C in Gujarat region and by <0.5oC in Punjab and two subdivisions of West Bengal. The remaining subdivisions are likely to experience warmer than normal minimum temperatures of 0.50C to 1 0C.
The season averaged mean temperature are likely to be warmer than normal by 0.50C to 1 0C in all the subdivisions of the entire country except Konkan and Goa, Karnataka, Kerala, Tamil Nadu, Rayalaseema and two subdivisions of West Bengal (in which mean temperatures are likely to be cooler than normal by 0.5oC). There is moderate (40%) probability of minimum temperatures in the core CW zone during the 2017/18 DJF season to be above normal.
Core CW zone covers states of Punjab, Himachal Pradesh, Uttarakhand, Delhi, Haryana, Jammu & Kashmir, Rajasthan, Uttar Pradesh, Gujarat, Madhya Pradesh, Chhattisgarh, Bihar, Jharkhand, West Bengal, Odisha and Telangana and met subdivisions of Marathwada, Vidharbha , Sourashtra and Madhya Maharashtra. This suggests occurrence of cold wave conditions in the core CW zone during the 2017/18 cold weather season is likely to be normal to less than normal.
The Monsoon Mission Climate Forecast System (MMCFS)
The present temperature outlook was prepared using MMCFS. The MMCFS has been used to prepare forecasts for the monsoon rainfall since 2012. MMCFS model developed by Indian Institute of Tropical Meteorology (IITM), Pune during the Monsoon Mission Phase was implemented and run operationally at the office of Climate Research and Services (CRS), IMD, Pune from January, 2017.
The MMCFS has a spatial resolution of about 38 km and improved modules of model physics. The model hindcasts and forecasts were bias corrected using data for the period 27 years (1982-2008). The seasonal temperature forecast outlook for the December 2017 to February 2018 was prepared based on the 2017 November initial conditions. The forecast was prepared using 31 ensemble member forecasts. The model showed moderate skill over many subdivisions over northwest and central India during the period 1982-2008. 4. ENSO conditions in the Pacific Ocean Currently, the SST conditions over equatorial Pacific suggest weak La Nina conditions. Atmospheric conditions are also indicating La Nina conditions.
The latest forecasts from MMCFS indicate strong probability for current La Nina conditions to persist at least till the winter season (DJF). Historical data indicates weak or no consistent association between La Nina and winter temperatures over India.
