The Country
experienced significantly above normal temperatures during the last two months
of January and February,2016, with monthly anomalies of 1.530C &
20C respectively from 1961-90 normal. The year 2015 was the third
warmest year ever recorded since 1901.
During the Hot
Weather Season of 2016 i.e. April to June warmer than normal temperatures are
expected in all meteorological sub-divisions of the country. Seasonal
(April-June) average temperatures over northwest India are expected to be above
normal by more than 10C. Above normal heat wave (HW) conditions are
very likely over central and northwest India during the Hot Weather Season of
2016.
The figures
below (Fig.1, Fig.2 & Fig.3) show the forecast for the subdivision-wise
averaged maximum, minimum and mean temperature anomalies (departures from the long
term normal) respectively over India for the hot weather season (April to June,
2016). The forecast indicates that during the hot weather season of 2016,
temperatures (mean, maximum and minimum) in all the sub-divisions are likely to
be above normal. All the temperatures (maximum, minimum and mean) of most of
the sub-divisions from northwest India, Kerala from south India and Vidharbha
from Central India are likely to be above normal by ≥10C.
The season
averaged maximum temperatures of coastal Andhra Pradesh, Odisha, Assam &
Meghalaya, sub-Himalayan West Bengal & Sikkim, and Nagaland, Mizoram,
Manipur, Tripura are likely to be warmer by <0.5oC and that of the remaining
subdivisions are likely to warmer than normal by 0.5 to 10C.
The season
averaged minimum temperatures of sub-Himalayan West Bengal & Sikkim, and
Nagaland, Mizoram, Manipur, Tripura are likely to be warmer than normal by
<0.5oC and that of the remaining subdivisions are likely to warmer
than normal by 0.5 to 10C.
The season
averaged mean temperatures of sub-Himalayan West Bengal & Sikkim, Nagaland,
Manipur Mizoram, & Tripura and Assam & Meghalaya are likely to be
warmer than normal by<0.5oC and that of the remaining
subdivisions are likely to warmer than normal by 0.5 to 1oC. There
is also a high probability (76%) of maximum temperatures in the core Heat
Wave(HW) zone during the hot weather season of 2016 to be above normal (Fig.4).
Core HW zone covers states of Punjab, Himachal Pradesh, Uttarakhand, Delhi,
Haryana, Rajasthan, Uttar Pradesh, Gujarat, Madhya Pradesh, Chhattisgarh,
Bihar, Jharkhand, West Bengal, Orissa and Telengana and met subdivisions of
Marathwada, Vidharbha, Madhya Maharashtra and coastal Andhra Pradesh. This in
turn suggests high probability of moderate and severe heat wave conditions in
core HW zone during the hot weather season.
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Many parts of
the country experience heat wave conditions during the hot weather season
leading to many adverse consequences. Abnormally above normal temperatures can
have devastating effects on human health, water resources and power generation
and outage. There is a marked relationship between human mortality and thermal
stress. During the summer of 2015, prolonged severe heat wave conditions
prevailed over Andhra Pradesh and parts of Telegana which claimed more than
2500 lives.
The recent
research analysis suggests that frequency and duration of heat waves over the
country are showing an increasing trend. A part of the increasing trend is
attributed to increasing greenhouse gases due to anthropogenic activity. In
addition, the ocean conditions over the equatorial Indian and Pacific oceans
also contribute to the variability of heat waves over the country. In the past,
El Nino events over the Pacific are known to cause severe heat wave conditions
over the country.
The strong El
Nino conditions over the Pacific Ocean that started in 2015 are still
continuing. However, the latest forecasts indicate that El Nino conditions are
likely to weaken further and reach weaker El Nino conditions during the hot weather
season of 2016. It has been observed that during the hot weather seasons
followed by El Nino years (for example: 1973, 1995, 1998, 2003, 2010, etc.
followed by the El Nino years of 1972, 1994, 1997, 2002 and 2009), above normal
temperatures including moderate to severe heat wave conditions were experienced
in most parts of India.
In view of its
social relevance, India Meteorological Department, Ministry of Earth Sciences
has initiated a seasonal outlook for summer temperatures over the country based
on predictions using an ocean atmosphere coupled climate model. From this
season, IMD will also provide extended range forecasts (5 –day averaged
forecasts for next 15 days) of heat wave conditions over the country. This
will be based on the Dynamical Extended Range Forecasting System developed by
IITM Pune. The forecast will consist of probability of occurrence of hot days,
heat waves and severe heat waves for the next 15 days updated every 5th day
from 1st April, 2016 onwards. The forecasts will be made available through
IMD, Delhi website (www.imd.gov.in).
Under the
Monsoon Mission, the Indian Institute of Tropical Meteorology (IITM), Pune of
the Ministry of Earth Sciences has been developing a state-of-the-art coupled
climate model for generating monsoon forecasts known as the Coupled Dynamical
Forecast System. The model has a spatial resolution of about 38 km and improved
modules of model physics. The model was used to prepare the monsoon forecasts
for the 2015 monsoon season. The analysis has shown that the same climate model
has useful skill for predicting seasonal temperatures during the Hot Weather
Season (April to June) over India. Therefore, this climate model was used to
prepare an outlook for the summer temperatures of 2016. The model climatology
was prepared using retrospective forecasts generated for 27 years (1982-2008)
based on the February initial conditions. The model showed moderate skill for
summer temperatures over many subdivisions over northwest and central India.
The forecast for the hot weather season of 2016 was prepared using 47 ensemble
member forecasts.
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KSP/VM