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08-19 April 2013

Macao, China

Country Report

Ranjit TamangAssistant Weather forecaster

Meteorology DivisionDepartment of Hydro-Met Services

Thimphu : Bhutan

Training Workshop on Severe Weather forecasting and warning services

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Total area:38,394 Sq. Km

Population: 672,000

Elevation: 100m-7000m

About Bhutan

Network and Current StatusNetwork and Current Status

1. Meteorological Network: 90– Class A Met Station 20 – Real-time AWS 09– Class C Met Station 70

2. Hydrological Network: 25– Principal Station 16– Secondary Station 9– Sediment Sampling Station 10

3. Flood Warning Network: 12– Flood Warning Station 12 3

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Flood warning activity is undertaken by the RGoB in collaboration between the Central Water Commission (CWC) of India;

Flood warning network stations are established on the north–south rivers that are common to India and Bhutan;

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The existing Weather Forecasting System in Bhutan

1. Developed format in excel basically for temperature forecast.

The format is developed to make short range forecast but it can be also use for medium range forecast.

2. MetGIS (weather forecasting software tool): MetGIS was developed with the collaboration of Vienna University, Department of Meteorology and Geophysics, Austria in the year 2010.

• It is a combined, Java-based, Meteorological and Geographic Information System that uses the latest forecast technologies.

• MetGIS is specialized in mountain weather predictions, since it combines meteorological forecast models with high-resolution geographic information systems (a completely new approach in meteorological forecast technology!), using so-called “downscaling-techniques”.

• Met GIS model, Data input: Global Forecast System (GFS) of the US National Weather Service.

It has a parameters like, 3 hourly rainfall, snowfall and Relative Humidity at a height 3000m. All output in graphic forms, it also has provision of a weeklong forecast in text format.

3. Other websites (South Asian Region)

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Here are some sample of Met GIS graphics outputs

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IMD Satellite kalpana-1

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Climatic ConditionClimatic Condition

• Bhutan Climate is generally dominated by monsoon winds

– Dry winter and wet summer monsoon

• Factors that governs the Climate of Bhutan Latitude Altitude Prevailing Wind Direction Orientation of Mountain Ranges Local Winds

Temperatures in degree celsius (max and Min) Mean (1996-2012)

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  Jan   Feb   Mar   Apr   May   Jun   Jul   Aug   Sep   Oct   Nov   Dec  

Stations Max/Min Max/Min Max/Min Max/Min Max/Min Max/Min Max/Min Max/Min Max/Min Max/Min Max/Min Max/Min

Deothang 20.5/10 21.9/11.7 24.6/14.8 25.4/16.7 26.8/18.9 27.6/20.6 28.1/21.3 28.7/21.3 28.1/20.4 27.5/17.6 25.0/14.3 22.3/11.4

Bhur 22.2/13 23.8/15.6 26.3/18.4 27.6/20.6 28.8/22.4 29.1/23.5 29.4/23.8 30.1/24.2 29.8/23.6 28.6/21.2 26.2/17.8 23.5/14.6

P/ling 23.4/14.2 26.5/15.7 29.4/18.6 30.9/20.2 32.2/22.2 32.4/23.3 31.9/23.9 32.3/24.2 31.6/23.4 31.0/21.4 28.4/18.2 24.8/14.8

Samtse 20.7/13.6 22.8/15.8 26.0/18.9 27.6/20.9 28.4/22.3 28.5/23.6 28.0/24.1 28.6/24.3 28.7/23.6 28.0/21.3 25.3/18.2 22.8/15.3

Pemagatshel 16.0/5.0 17.3/6.7 20.1/9.7 22.4/12.5 24.3/15.0 25.1/16.9 25.7/17.6 25.6/17.3 25.3/16.2 23.8/12.8 20.7/9.1 18.0/6.4

Zemgang 12.7/4.7 13.9/6.3 17.0/9.7 19.4/12.8 21.1/15.3 22.5/17.4 23.0/18.0 23.0/17.9 22.4/17.7 20.2/13.2 17.1/9.4 14.1/6.1

Tsirang 14.5/4.6 15.9/6.3 18.9/9.6 21.1/13.2 22.5/15.9 23.3/18.2 23.6/18.8 24.0/18.6 23.5/17.4 22.0/13.6 19.3/9.4 16.4/5.9

Dagana 11.6/6.3 12.9/7.3 16.8/10.8 19.8/14.1 21.9/16.1 23.0/17.7 22.9/18.5 22.9/18.3 22.1/17.1 20.1/15.1 16.4/10.9 13.5/8.3

Chukha 13.3/5.3 14.5/6.5 17.6/9.2 20.0/11.3 22.2/13.5 23.9/15.7 23.9/15.5 23.6/14.9 22.9/14.1 21.5/12.3 18.5/9.4 15.1/6.7

Tashigang 14.0/3.1 15.9/4.6 19.3/7.7 21.5/10.7 23.2/13.5 24.2/16.0 24.4/16.9 24.9/16.7 24.3/15.6 22.3/11.7 18.8/7.8 15.9/4.6

Mongar 16.3/5.6 18.7/7.1 21.7/10.6 23.9/13.2 25.5/15.0 26.5/17.4 26.6/18.0 27.4/17.9 26.7/16.9 24.5/13.6 20.8/10.0 17.9/7.0

Bhumthang 11.1/-3.8 12.4/-1.2 15.2/1.8 17.6/5.7 19.8/9.4 21.8/12.8 22.7/14.3 22.6/14.1 21.4/12.1 18.5/6.8 15.3/1.3 12.6/-3.0

Trongsa 14.4/2.7 16.0/3.6 19.3/7.0 21.5/10.3 22.5/12.5 23.5/15.5 23.8/16.7 24.6/16.4 23.8/15.1 21.7/10.6 17.7/5.7 15.6/3.7

Wangdi 18.2/5.6 19.4/7.9 23.0/10.8 26.1/14.2 28.0/17.5 28.9/20.1 28.4/20.6 28.5/20.5 27.7/19.4 26.1/15.0 22.8/9.9 19.8/6.0

Punakha 17.9/6.1 19.4/7.6 22.6/10.7 25.3/14.0 27.9/17.2 29.5/19.6 29.6/20.3 29.2/19.5 28.1/18.0 26.3/15.9 22.6/11.8 19.5/7.5

Thimphu 14.7/-2.7 15.9/-0.3 18.5/3.5 21.0/7.1 22.9/11.0 24.6/14.6 25.0/16.0 25.2/15.5 24.0/13.8 21.6/8.2 18.5/2.5 16.3/-1.5

Paro 13.4/0.2 14.8/2.0 18.0/4.9 20.7/8.4 22.8/11.7 24.6/14.9 25.3/16.8 25.1/16.4 23.5/14.7 20.7/10.0 16.4/5.0 14.4/1.5

Haa 10.8/-5.0 11.2/-2.9 13.6/0.9 16.0/4.8 18.2/8.8 19.8/12.5 20.7/14.2 20.7/13.7 19.2/11.7 17.0/5.6 14.4/0.1 11.9/-3.6

Trashiyangtse 13.0/3.2 15.0/5.4 17.9/7.7 20.5/10.5 22.5/13.7 24.2/16.6 24.6/18.0 24.4/17.6 23.7/16.6 21.2/12.2 18.0/7.6 14.7/4.0

Lhuentse 17.1/7.2 19.2/9.2 23.3/12.0 26.0/14.8 27.3/17.1 28.6/19.7 28.8/19.9 29.0/19.9 27.8/19.0 25.8/15.4 22.4/11.2 18.0/8.3

Gasa 9.5/-0.2 9.9/0.6 13.0/4.1 16.1/8.2 18.3/9.3 19.4/11.5 21.5/12.7 21.2/12.0 20.0/11.7 17.9/9.3 13.7/3.7 11.6/0.2

Stations Annual TRF mean (1996-2012)

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Sations Name Altitude RF in mm

Deothang  300.0 mtrs 3859.7

Bhur  375.0 mtrs 5163.8

P/ling 220.0 mtrs 4017.8

Samtse 550.0 mtrs 5559.3

Pemagatshel 1618.0 mtrs 1819.5

Zemgang 1905.0 mtrs 1370.3

Tsirang 1520.0 mtrs 1718

Dagana 1460.0 mtrs 1875.8

Chukha 1600.0 mtrs 1525

Tashigang 1930.0 mtrs 1188.4

Mongar 1600.0 mtrs 890.3

Bhumthang 2470.0 mtrs 750.6

Wangdue 1180.0 mtrs 669.9

Punakha 1236.0 mtrs 671.6

Thimphu 2380.0 mtrs 660.4

Paro 2406.0 mtrs 605.6

Haa 2720.0 mtrs 871.4

Trashiyangtse 1830.0 mtrs 1164.8

Lhuentse 1380.0 mtrs 775.2

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Bhutan Seasonal RF distribution annual rainfall received in different seasons

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Major factors contribution for Heavy rainfall in Bhutan

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SW Monsoon Bhutan received 72% of the annual total rainfall from SW monsoon

Cyclone In the year 2009 cyclone Aila, which hit the Bay of Bengal in May, had a

disastrous impact in Bhutan, impacting power and water supplies and damaging roads, bridges and other infrastructure. 

Short duration high intensity rainfall

Simulation of RF during Cyclone Aila across the country in the year 2009

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Hazards associated with Heavy Rainfall in Bhutan

1. Flash Floods

2. Floods

3. Landsides

Flash Flood Events in BhutanIn August 2000 flood killed 49 people and destroyed 17 houses in Pasakha, in Southern Bhutan

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3. Land slides Young fragile geology and steep

slopes of the country is highly susceptible to landslides during rainy season.

Most landslides occur in the eastern and southern foothills where the terrain is steep and rocks underlying the soil cover are highly fractured, allowing easy seepage of water.

Scores of landslides across the National Highway occurred every year during the monsoon, hampering moment of transport for several weeks.

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Long range and seasonal forecast, specially monsoon forecast will be carried out in Bhutan in near future.

WRF Model was installed in Meteorology Division,Department of Hydro met. Services under the guidance of Expert from SMRC, Dhaka (Mr. Sujit Kumar Debsarma) in May 2012.

Conclusion

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Thank you

&

TASHI DELEK!