Last week’s trough of low at mean sea level over south Andaman Sea & adjoining Malaya peninsula laid over south Andaman Sea & neighbouring areas with cyclonic circulation aloft extending upto 3.1 km above mean sea level moved westwards and caused rainfall at most places on 29th, 30th & 31st December 2017 over Nicobar Islands with heavy rain on 30th & 31st December and rainfall at many places over Andaman & Nicobar Islands on 3rd January 2018.
Last week’s Western Disturbance as a trough in midtropospheric level westerlies lay as a cyclonic circulation over north Pakistan & neighbouring areas and moved east-northeast wards and caused isolated rain/snow over Himachal Pradesh on 2nd January 2018.
A cyclonic circulation over east Bangladesh & neighbouring areas caused isolated rainfall over Assam & Meghalaya and Nagaland, Manipur, Mizoram & Tripura on 2nd & 3rd January and over Arunachal Pradesh on 3rd January 2018.
Isolated rainfall also occurred over Coastal Andhra Pradesh, Rayalaseema and Tamil Nadu & Puducherry on one/two days of the week.
Ground frost was observed at isolated places over East Rajasthan in the plains of the country on 3rd January 2018.
During the week, lowest minimum temperature 0.0°C recorded at Sikar (East Rajasthan) in the plains of the country on 3rd January 2018.
During the week, lowest maximum temperature of 11.8°C was recorded at Aligarh (West Uttar Pradesh) in the plains of the country on 3rd January 2018.
Dense to very dense Fog occurred at many places on most of the days of the week over Uttar Pradesh, Haryana, Chandigarh & Delhi, Punjab, Bihar, Sub-Himalayan West Bengal, on few days over Assam & Meghalaya, Nagaland, Manipur, Mizoram & Tripura, East Madhya Pradesh and on one/two days over West Madhya Pradesh, Jharkhand, Uttarakhand and Himachal Pradesh.
Cold wave / severe cold wave conditions prevailed on few days of the week over Haryana, Rajasthan, East Madhya Pradesh, Telangana, Vidarbha and North Interior Karnataka and on one/two days over Punjab, Interior Odisha, Chhattisgarh, Jammu & Kashmir and Himachal Pradesh.
Cold day / severe cold day conditions prevailed at a few places over East Uttar Pradesh and Bihar on a few days of the week and at isolated places over Haryana, Punjab and Eastern Madhya Pradesh.
The cumulative rainfall Sub-Division wise for the week (28 December 2017 - 03 January 2018) predicted by the IMD GFS model shows that Andaman & Nicobar Islands would receive excess rainfall and it has had excess rainfall. Konkan & Goa would receive normal rainfall and it has not actually received any rainfall. In northeastern states Arunachal Pradesh & Assam & Meghalaya would not receive any rainfall and Nagaland, Manipur, Mizoram & Tripura would receive deficient rainfall but Assam & Meghalaya and Nagaland, Manipur, Mizoram & Tripura received excess rainfall and Arunachal received largely deficient rainfall. Rayalassema would not receive any rainfall whereas it actually received largely deficient rainfall.
Overall model has over predicted rainfall in Jammu & Kashmir & Konkan & Goa and under predicted rainfall in Arunachal Pradesh, Assam & Meghalaya and Nagaland, Manipur, Mizoram & Tripura. Except these 8 Sub-Divisions the model has predicted well for other 28 Sub-Divisions.
During the week, rainfall over the country as a whole was 89 per cent below the long period average (LPA). All the four broad homogeneous regions of India received largely deficient rainfall. Details of rainfall distribution over the four broad homogeneous regions of India are given below:
For the country as a whole, cumulative rainfall was (-10 per cent) of LPA as on 31st December 2017.Cumulative rainfall was deficient over northwest India. Rainfall was excess / normal over the most of the sub-divisions of east & northeast India and southern peninsula and few sub-divisions of central India. Details of rainfall distribution over the four broad homogeneous regions of India are given below:
28 DECEMBER 2017: NIL
29 DECEMBER 2017: ANDAMAN & NICOBAR ISLANDS: MAYA BANDAR-6, PORT BLAIR-1, HUT BAY-1
30 DECEMBER 2017: ANDAMAN & NICOBAR ISLANDS: CARNICOBAR (IAF)-8, NANCOWRY-2, HUT BAY-2, CARNICOBAR-1.
31 DECEMBER 2017: ANDAMAN & NICOBAR ISLANDS: CARNICOBAR -14, CARNICOBAR (IAF)-5.
01 JANUARY 2018: NIL
02 JANUARY 2018: HIMACHAL PRADESH: KANDAGHAT-3, KUMARSEN-2.
03 JANUARY 2018: ANDAMAN & NICOBAR ISLANDS: NANCOWRY-5, CARNICOBAR-5, MAYABANDER-4, HUT BAY-4, CARNICOBAR (IAF)-4, ASSAM & MEGHALAYA: LUMDING-1, BOKAJAN-1; NAGALAND, MANIPUR, MIZORAM & TRIPURA: JHARNAPANI-2, KIPHIRE-1