INTERPRETATION of Weather Portal by India Meteorological Department

INTERPRETATION of Weather Portal by India Meteorological Department G K DAS Director Area Cyclone Warning Centre Regional Meteorological Centre, Kolkata E-mail: ganesh. das@imd. gov. in

General Weather affecting Eastern India 1. Eastern India consist of the six met subdivisions, comprising of five states of eastern India namely West Bengal, Sikkim, Bihar, Jharkhand Odisha. West Bengal consist of two sub division namely Gangetic West Bengal (GWB) and Sub Himalayan West Bengal (SHWB). SHWB and Sikkim form a single subdivision. 2. SHWB & Sikkim is dominated by orography mainly associated with Eastern Himalayas. 3. GWB and Odisha is mainly coastal subdivision. Bihar and Jharkhand is landlocked state/subdivision.

General Weather affecting Eastern India-continued 4. Eastern India experienced weather throughout the year. (a) Winter during second fortnight of December to first fortnight of February. (b)Summer season during March to May with a severe thunderstorm reaching wind speed 120 kmph over the region with sharp fall of temperature and rise of relative humidity (c) Rainy season start from June and continued upto September having heavy (711 cm) to very heavy rainfall (12 -20) cm along with extremely heavy rainfall ( ≥ 21 cm) associated with monsoon low pressure system. (d)Gangetic West Bengal and Odisha affected directly by Tropical Cyclone (TC) over Bay of Bengal during post monsoon season (October-December) and premonsoon (April-May). Severe weathers like heavy rainfall, high wind speed and storm surge associated with TC affect the coastal district of West Bengal and Odisha. Rest of the Eastern India affected by heavy rainfall. Heavy rainfall bring flood over the region during monsoon and TC season. State of Sikkim and Darjeeling district of West Bengal experience snowfall during winter season.

Content available in the website amssdelhi. gov. in/ERLDC/MAIN. html Regional Weather Summary Weather Warning Radar Satellite Meteogram Nowcast Bay Bulletin

General Weather Summary and Warning 1. This forecast is being used based on different type of chart analysis (Surface chart, Upper air chart and change chart), monitoring of satellite picture and with running of Numerical Weather Prediction (NWP) model 2. This section contains general weather information regarding occurrence of rainfall in summary parts and heavy rainfall warning 3. This is issued at both subdivision level and district level 4. This is for 5 days forecast with 2 days weather outlook for rainfall and for 5 days warning for heavy rainfall 5. It is updated twice daily.

Regional Weather Summary

Regional Weather Warning

District Level Weather Summary

District Level Weather Warning

Doppler Weather Radar (DWR) 1. DWR is the best tool for nowcasting. DWR is used to track Tropical Cyclone when it comes under DWR ranges. Thunderstorms/squalls are also track/forecasted by DWR. 2. Various DWR products like Maz (Z), PPI and VVP are used for heavy rainfall/thunderstorm forecasting. 3. In eastern India Kolkata, Paradip and Patna has DWR. 4. This products are available in every 10 minutes intervals

MAX(Z) product 1. This product is used to see both the intensity of cloud as well as height of cloud 2. This picture shows the cloud around Kolkata and surrounding area with cloud height of about 6 -8 km 3. It has a moderate intensity/severity of 44 -50 d. BZ. 4. Anything above 50 d. BZ with big cluster of cloud convection is indictation of severe weather events like squall associated with thunder, lightining and heavy rainfall 5. Its range is about 250 km

Plan Position Indicator(PPI) and Volume Velocity Processing (VVP) 2 1. PPI is used to locate the convective cloud over range of 500 km range (First Figure) with intensity 2. VVP is used to see the wind velocity and wind direction in a vertical column above the RADAR site 3. VVP 2 is mainly used the see as steering current for the movement of cloud mass and also moisture incursion

VVP 2 Product

Satellite is the one of the most important tool to monitor the development, intensification and movement of Tropical Cyclone (CS)when it is in the deep sea. IMD monitor CS through INSAT 3 D, INSAT 3 DR and Kalpana-1. Various types of channel/satellite product are used to predict its development and intensity. All the severe weather events can be monitor by different type of satellite product

Types of satellite picture 1. Infrared (IR) image display mixed cloud (low, medium and high cloud). Most of the derived product is obtained from IR image. 2. Visible image display basically low cloud 3. Water Vapour image display high cloud and moisture depth in the atmosphere 4. CTBT indicates the cloud top temperature based on IR images 5. Brightness Temperature image helps in displaying convection

Visible Image

IR image

Water Vapour image

CTBT image

Brightness Temperature image

Nowcasting Current weather and forecasts upto a few hours ahead are given. This nowcast is given mainly for severe weather like squall, hailstorm and flash heavy rainfall during next 2 to 3 hours based on WDSS II and various DWR product

Meteogram 1. Meteogram is a graphical representation of one or more meteorological variable with respect to time. 2. IMD is generating more than 250 city based meteogram with validity of 10 days. 3. Its contains information rainfall, cloud coverege, wind speed and direction, temperature etc.

Bay Bulletin This part contains two type of bulletin 1. Sea Area Bulletin: It contains information regarding visibility and wind over seas area. 2. Coastal Area Bulletin: This contains information regarding visibility, wind, weather, sea condition and port warning. 3. RMC Kolkata is responsible for entire Bay of Bengal and Andaman Sea region to provide the sea area and coastal area bulletin.

Bulletin and warning issued during Cyclone

Meteorological Parameters affecting Power Sector EXTREME TEMPERATURE The extreme temperature like very hot or very cold may be one of the significant factor for power generation as well as power distribution. Hence Heat wave and cold wave warning is very important HEAVY RAINFALL Heavy to very heavy rainfall may be a factor in power sector WIND SPEED AND DIRECTION During severe weather particularly Norwester and Cyclone period sudden rise of wind speed may be an important factor Hence Nowcast during pre-monsoon season and general warning during Cyclone/Depression is very important FOG As it is associated with relative humidity dense fog may affect the Power Distribution Hence Fog forecast/warning is very important

Warning Dissemination Mechanism Telephone, Tele-fax Mobile Phones(SMS)/Whatsapp message Satellite based cyclone warning dissemination System Internet (e-mail) Websites ( imd. gov. in/imdkolkata. gov. in) Radio/TV, News Paper network (FM, Comminity Radio, Private TV): Prasar Bharati and private broadcasters v Briefing by Senior Officer (Director/DDGM) to Chief Secretary and other Disaster Manager v Briefing to electronic media and print media v v v

Weather related information and contact details RMC/ACWC Kolkata Control Room: 033 -2479 -3167 DDGM Office: 033 -24793782 Website : www. imdkolkata. gov. in MC Bhubaneswar Control Room: 0674 -2596093 Website: www. imdorissa. gov. in MC Patna Control Room: 0612 -2226556/6632 MC ranchi Control Room: 0651 -2501572/2502103 MC gangtok Control Room: 3592 -203427 Website: www. imdsikkim. gov. in

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