Ministry of Earth Sciences Earth System Science Organization India Meteorological Department WMO Regional Climate Centre (Demonstration Phase) Pune, India Seasonal Climate Outlook for South Asia (April to July 2015) Issued in March 2015 DISCLAIMER: (1) The long range forecasts presented here are currently experimental and are produced using techniques that have not been validated. (2) The content is only for general information and its use is not intended to address particular requirements. (3) The geographical boundaries shown in this report do not necessarily correspond to the political boundaries. Currently warm ENSO neutral/ border line El Nino conditions are prevailing over equatorial Pacific with sea surface temperatures across most of the equatorial pacific are warmer than normal. The latest coupled model forecast suggest, the conditions to reach weak El Nino level during the middle of the year. The 2015 AMJ mean precipitation is likely to be wetter than normal over Northeast India, Bhutan, eastern part of Bangladesh, Bay of Bengal, northern most areas of India, Pakistan and Afghanistan, southern most areas of India and Sri Lanka and normal over remaining areas. The 2015 MJJ mean precipitation is likely to be wetter than normal over Sri Lanka, and northern most areas of India, Pakistan and Afghanistan, drier than normal MJJ precipitation over most parts of Myanmar, Bhutan and northern most parts of Northeast India and normal over the remaining areas. The 2015 AMJ mean temperatures are likely to be warmer than normal over Peninsular India, extreme North India, west India and neighbouring south Pakistan, and some areas of eastern Bangladesh and neighbouring Myanmar, cooler than normal over some areas of central Afghanistan and southwest Bangladesh and normal over remaining areas. The MJJ mean temperatures are likely to be nearly same as during AMJ. The country averaged monthly precipitation likely to be normal to wetter than normal for Afghanistan and Pakistan and normal to drier than normal for Sri Lanka. In July, monthly rainfall is likely to be drier than normal over all the countries except for Afghanistan and Pakistan. The country averaged monthly temperature is likely to be warmer than normal for Pakistan during all the four months, for Afghanistan during the first 3 months, for Sri Lanka during the last 3 months, and for Bhutan, India during the last two months.
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Ministry of Earth Sciences Earth System Science Organization
India Meteorological Department
WMO Regional Climate Centre
(Demonstration Phase)
Pune, India
Seasonal Climate Outlook for South Asia
(April to July 2015)
Issued in March 2015
DISCLAIMER: (1) The long range forecasts presented here are currently experimental and are produced using techniques that have not been validated. (2) The content is only for general information and its use is not intended to address particular requirements.
(3) The geographical boundaries shown in this report do not necessarily correspond to the political boundaries.
Currently warm ENSO neutral/ border line El Nino conditions are prevailing over equatorial Pacific
with sea surface temperatures across most of the equatorial pacific are warmer than normal. The
latest coupled model forecast suggest, the conditions to reach weak El Nino level during the
middle of the year.
The 2015 AMJ mean precipitation is likely to be wetter than normal over Northeast India, Bhutan,
eastern part of Bangladesh, Bay of Bengal, northern most areas of India, Pakistan and
Afghanistan, southern most areas of India and Sri Lanka and normal over remaining areas. The
2015 MJJ mean precipitation is likely to be wetter than normal over Sri Lanka, and northern most
areas of India, Pakistan and Afghanistan, drier than normal MJJ precipitation over most parts of
Myanmar, Bhutan and northern most parts of Northeast India and normal over the remaining
areas.
The 2015 AMJ mean temperatures are likely to be warmer than normal over Peninsular India,
extreme North India, west India and neighbouring south Pakistan, and some areas of eastern
Bangladesh and neighbouring Myanmar, cooler than normal over some areas of central
Afghanistan and southwest Bangladesh and normal over remaining areas. The MJJ mean
temperatures are likely to be nearly same as during AMJ.
The country averaged monthly precipitation likely to be normal to wetter than normal for
Afghanistan and Pakistan and normal to drier than normal for Sri Lanka. In July, monthly rainfall is
likely to be drier than normal over all the countries except for Afghanistan and Pakistan.
The country averaged monthly temperature is likely to be warmer than normal for Pakistan during
all the four months, for Afghanistan during the first 3 months, for Sri Lanka during the last 3
months, and for Bhutan, India during the last two months.
1. Important Global Climate Factors
1.1 Sea Surface Temperatures over the Pacific Ocean
The monthly mean Sea Surface Temperature (SST) anomalies (Fig.1) for February
show warm SST anomalies in the central Pacific around the date line. Warm SST anomalies
were also observed over northeast Pacific with anomalies greater than 10C along the west
coast off the North American continent. However, cool SST anomalies were observed over
East and Central parts of subtropical South Pacific Ocean. In February, warm SST
anomalies were observed over all the Nino regions except NINO1+2 (Fig.2). During last 3
months, cooling of SSTs was observed over all the 4 Nino regions. However, the latest
forecast from the coupled model indicate warming of SSTs is likely over all the Nino regions
during the next 9 months, which may lead weak El Nino conditions to set up during the
middle of the year.
Fig. 1: Average SST anomalies (0C) for February 2015. (Data source: INCOIS-GODAS).
Fig.3: The time series of the monthly Dipole Mode Index (DMI) representing Indian Ocean Dipole (IOD). Observed anomaly for the last 3 months (Source: INCOIS-GODAS) and IITM-CFS model forecast anomaly for the next 9 months.
Fig.2: Time series of monthly area-averaged SST anomalies (°C) in the 4 Niño regions. Observed anomaly for the last 3 months (Source: INCOIS-GODAS) and IITM-CFS model forecast anomaly for the next 9 months.
1.2 Sea Surface Temperatures over Indian Ocean
During February, cool SST anomalies were observed over west equatorial Indian Ocean and north Arabian Sea (Fig.1). Warm SST anomalies observed over the Bay of Bengal in January, now have been replaced by cooler SST anomalies. Warm SST anomalies were also seen over southeast Arabian Sea and tropical Southeast Indian Ocean northwest off Australian coast. The Dipole mode Index during February was negative and its magnitude was nearly same as that in January. The latest forecast (Fig.3) from the coupled model shows weakening of DMI in the next 9 months resulting near normal Indian Ocean Dipole conditions to continue till the end of the year.
Fig. 4: Convection (OLR) Anomaly (W/m2) Pattern over the Asia Pacific Region for February 2015 (Data source: NCEP-NOAA)
1.3 Convection (OLR) Anomaly Pattern over the Asia Pacific Region:
The convective activity in terms of outgoing long wave radiation (OLR) anomalies for
February 2015 is shown in Fig.4. Slightly positive OLR anomalies (supressed convection, red shading) were observed over maritime continent, northern Australia and equatorial Pacific east of date line. On the other hand, negative OLR anomalies (enhanced convection blue shading) were observed over Indian land mass, central parts of subtropical south Indian Ocean, tropical west Pacific west of date line and over tropical east Pacific along the west coast off North America. Strong negative OLR anomalies were also seen over Sahel region of Africa and Madagascar.
1.4 Snow Cover Area over the Northern Hemisphere (NH):
February shows reduced snow cover over Northern Hemisphere and Eurasia. The NH
snow cover area (44.98 million sq. Km) was less than the 1981-2010 normal by 606
thousand Sq. km. Eurasian Snow cover in February was 27.59 million Sq. Km with negative
departure of 885 thousand Sq. km than compared to the 1981-2010 normal. Canada and
North America have normal snow cover with a slight positive departure of 279 and 72
thousand Sq. km respectively when compared to the 1981-2010 normal.
1.5. Madden Julian Oscillation (MJO):
During the nearly first half of February, MJO was in phases 7 and 8, which
subsequently weakened during the second half of the month.
2. Seasonal Outlook for South Asia
The outlook was prepared based on the forecast from the India Meteorological
Department (IMD)’s seasonal forecast model (SFM). The model is a hydrostatic global
spectral model with a triangular truncation of 62 (T62) spherical harmonics (horizontal
resolution of about 250 km) and a vertical sigma coordinate system of 28 layers. The
ensemble simulations were carried out for 31 year period from 1982 to 2012 to prepare the
model climatology. Each forecast was initialized using atmospheric conditions for first 10
days of March, and run continuously for next five months. The forecasted SSTs from the
Coupled model, NCEP Climate Forecast System version 2 (CFSv2) were used as the
boundary conditions.
2.1. Precipitation Anomaly:
The seasonal forecasts for precipitation anomalies for the seasons April to June
(AMJ) 2015 and May to July (MJJ) 2015 are given in the Figures 5a and 5b respectively. The
AMJ precipitation anomaly forecast indicates wetter than normal precipitation over Northeast
India, Bhutan, eastern part of Bangladesh, Bay of Bengal, northern most areas of India,
Pakistan and Afghanistan, southern most areas of India and Sri Lanka. The AMJ
precipitation is likely to be near normal over remaining parts of the region (Fig.5a). The MJJ
precipitation anomaly forecast indicates normal precipitation over Nepal, most areas of India,
Pakistan and Afghanistan (Fig.5b). However, wetter than normal MJJ precipitation is likely
over Sri Lanka, and northern most areas of India, Pakistan and Afghanistan. Drier than
normal MJJ precipitation is likely over most parts of Myanmar, Bhutan and northern most
parts of Northeast India.
2.2. Temperature Anomaly:
The temperature anomaly forecast for 2015 AMJ season (Fig.6a) indicate warmer
than normal temperatures over Peninsular India, extreme North India, west India and
neighbouring south Pakistan, and some areas of eastern Bangladesh and neighbouring
Myanmar. Cooler than normal temperatures are likely over some areas of central
Afghanistan and southwest Bangladesh. However temperatures over remaining areas of the
region are likely to be normal. During MJJ season (Fig.6b), conditions are likely to be nearly
similar to that of AMJ season expect for warmer than normal temperature conditions over
west India and neighbouring areas Pakistan observed during AMJ season changing to near
normal temperature conditions during MJJ season.
a) b)
Fig.5: Seasonal forecasts of precipitation anomalies (mm/day) for (a) AMJ and (b) MJJ (right) based on Initial conditions of March 2015.
(a) (b)
Fig. 6: Seasonal temperature anomalies (0C) for (a) AMJ and (b) MJJ (right) based on Initial conditions of March 2015.
3 Forecast Outlook for the Country Averaged Monthly Precipitation and
Temperature
The model forecast for monthly precipitation and temperature for the next four months
(from March to June) averaged over the 8 south Asian countries viz., Afghanistan,
Bangladesh, Bhutan, India, Myanmar, Nepal, Pakistan and Sri Lanka is shown in the Figures
7 & 8 respectively. The monthly rainfall anomaly is expressed as percentage departure from
long period model average (LPMA) and monthly temperature anomaly is expressed in
degree Celsius.
In April, the country averaged monthly precipitation over all the south Asian
countries is likely to be normal for Sri Lanka and wetter than normal for all other countries
(Fig 7). In May, the monthly precipitation is likely to be wetter than normal for Bangladesh &
Myanmar, drier than normal for Nepal and normal for the remaining countries. In June, the
monthly precipitation is likely to be wetter than normal for Afghanistan, Bangladesh, Bhutan
and India, drier than normal for Myanmar and Nepal, and normal for remaining countries. In
July, it is likely to be wetter than normal for Afghanistan and Pakistan, and drier than normal
for all other countries. Thus during all the four months, the monthly precipitation is likely to
be normal to wetter than normal for Afghanistan and Pakistan and normal to drier than
normal for Sri Lanka.
In April, the country averaged monthly temperature is likely to be warmer than normal
for Afghanistan, Bangladesh and Pakistan, and normal for the remaining countries (Fig 8).
In May, the country averaged monthly temperature is likely to be warmer than normal for
Afghanistan, Bhutan, India, Pakistan and Sri Lanka, and normal for the remaining countries
of the region. In June, the country averaged monthly temperature is likely to be warmer than
normal for Bangladesh, Bhutan, India, Myanmar, Pakistan and Sri Lanka, and normal for the
remaining countries of the region. In July, the country averaged monthly temperature is likely
to be slightly warmer than normal for Bangladesh, Bhutan, India, Myanmar, Pakistan and Sri
Lanka, and normal for the remaining countries of the region. Thus monthly temperatures is
likely to be warmer than normal for Pakistan during all the four months, for Afghanistan
during the first 3 months, for Sri Lanka during the last 3 months, and for Bhutan and India
during the last two months. However, the monthly temperature for Nepal is likely to be
normal but negative during first 3 months.
APR MAY JUNE JULY APR MAY JUNE JULY
Fig.7: Monthly rainfall Averaged over
south Asian countries expressed as
percentage departures (%) during
April to July, 2015.
Fig.8: Monthly temperature anomaly (°C) averaged over south Asian countries during April to July, 2015.