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.