AND
ECONOMIC AND SOCIAL COMMISSION
FOR ASIA AND THE PACIFIC
WMO/ESCAP Panel on Tropical Cyclones
Fortieth session
Colombo, Sri Lanka
25 February to 1 March 2013 / FOR PARTICIPANTS ONLY
WRD/PTC-40/Doc. 5.1, ADD1
(19.II.2013)
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ENGLISH ONLY
REVIEW OF THE COORDINATED TECHNICAL PLAN AND CONSIDERATION
OF THE WORK PROGRAMME FOR THE NEXT FIVE YEARS
Meteorological Component
(Submitted by the WMO Secretariat)
SUMMARY AND PURPOSE OF DOCUMENT
This document provides the report of the Workshop and Case Study of Tropical Cyclone Analysis and Forecasting of the Working Group on Meteorology, which was held in Muscat, Oman from 17 to 19 December 2012 according to the decision of the Panel made at its 39th session in Myanmar (March 2012). The workshop was aimed at investigation as to the cause of inconsistencies between the advisories of RSMC and the forecast of NMHSs of the Panel Members.ACTION PROPOSED
The Panel is invited to review the report, in particular the recommendations made by WGM at the workshop. Panel may give guidance to WGM for further actions to take for improvement of the situation towards more adequate and coordinated forecasting/warning services in the Panel region.
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ATTACHMENT: Draft report of the Workshop and Case Study of Tropical Cyclone Analysis and Forecasting (Muscat, Oman, 17-19 December 2012)
WORLD METEOROLOGICAL ORGANIZATION
AND
ECONOMIC AND SOCIAL COMMISSION
FOR ASIA AND THE PACIFIC
Workshop and Case Study of Tropical Cyclone Analysis and Forecasting
Muscat, Oman, (17 - 19 December 2012)
(DRAFT)
FINAL REPORT
WMO/ESCAP PANEL ON TROPICAL CYCLONES
Working Group on Meteorology
1. INTRODUCTION
At the kind invitation of the Government of Oman, the Workshop and Case Study of Tropical Cyclone Analysis and Forecasting was held in Muscat, Oman from 17 to 19 December 2012. The workshop was organized by the Working Group on Meteorology (WGM) of the WMO/ESCAP Panel on Tropical Cyclones (PTC) according to the recommendation of the 39th session of PTC (5-9 March, 2012, Nay Pyi Taw, Myanmar).
2. BACKGROUND AND OBJECTIVE
At the 39th session, a problem was presented by the Members about inconsistencies between the advisories of RSMC New Delhi and the forecasts of NMHSs of the Members which were found in some cases of the tropical cyclones affecting the region during the 2011 cyclone season. In view of more adequate and consistent forecasting/warning services in the region, PTC decided to hold a face-to-face meeting of WGM with participation of RSMC and the Members concerned for achieving the better coordination among the Panel Members in the operational tropical cyclone analysis and forecasting procedures.
3. ORGANIZATION OF THE WORKSHOP
The workshop was attended by the forecasters of Bangladesh, India, Myanmar, Oman, Pakistan and Sri Lanka. The list of the participants is given in Appendix I. It was also attended by the staff members of the Meteorology and Air Navigation of Oman as observers.
Workshop was focused mainly on 1) RSMC advisories distributed to the Members, 2) operational forecasting procedures in RSMC and the Members, 3) case studies on the cyclones with significant discrepancies between RSMC and the Members forecasts, and 4) general discussion for improvement of the situation and recommendations.
The programme and agenda of the workshop can be found in Appendix II. Members’ reports summarizing their forecasting procedures are given in Appendix III. Members of different participating countries appreciated the cooperation extended by RSMC, New Delhi, especially in terms of issue of bulletins like tropical weather outlook & tropical cyclone advisory bulletins, cyclone best track data and graphics in electronic form available in IMD website and the reports on individualy cyclonic disturbances prepared by RSMC, New Delhi and shared with the member countries. The analytical consideration of the current problems with respect to consistency in RSMC advisory bulletin and bulletin issued by member countries are given in Appendix IV and recommendations of the workshop are in Appendix V. PowerPoint presentations made by RSMC and the Members during the workshop are also available from the WMO/TCP website together with this final report at http://www.wmo.int/pages/prog/www/tcp/Activities.html.
LIST OF PARTICIPANTS
MEMBERS / ParticipantsBANGLADESH / Mr Shamsuddin AHMED
Bangladesh Meteorological Department
INDIA / Dr. M. MOHAPATRA
India Meteorological Department
MYANMAR / Mr Kyaw Lwin OO
Department of Meteorology and Hydrology
OMAN / Mr Khalid Khamis Saif ALJAHHWARI
Department of Meteorology
pakistan / Mr Muhammad HANIF
Pakistan Meteorological Department
WMO SECRETARIAT / Mr Koji KUROIWA
Tropical Cyclone Programme
APPENDIX II
WORKSHOP PROGRAMME
APPENDIX II
APPENDIX III
Tropical Cyclone Warning System in Bangladesh
Organization
The Bangladesh Meteorological Department is responsible for providing tropical cyclone warnings to Bangladesh and its coastal areas and for a designated portion of the high seas in the Bay of Bengal. Warnings and forecasts are issued under the authority of the Director, Bangladesh Meteorological Department.
The tropical storm warnings are provided from the Storm Warning Centre, Agargaon, Dhaka1207. This Centre is also responsible for issuing the weather warnings like “Nor’westers” (severe local storms) warning, etc.
Tracking
The tropical cyclones are tracked with the help of conventional observations, radar, satellite observations and model derived products.
Tropical cyclone warnings
Tropical cyclone warnings are provided to:
(i) The Honourable President
(ii) The Honourable Prime Minister
(iii) Control room, Ministry of Food and Disaster Management (MoFDM)
(iv) All ministries
(v) The Sea Port Authorities at Chittagong, Mongla and Cox’s Bazar
(vi) The Cyclone Preparedness Programme (CPP), Bangladesh Red Crescent Society
(vii) The Armed Forces division, Bangladesh Navy, Bangladesh Air Force
(viii) Inland river ports authorities
(ix) Airport authorities
(x) Concerned government officials
(xi) The general public (through Betar (Radio) Television, electronic media and mass- media)
(xii) Fishing boats and trawlers in the sea
(xiii) Coast Guard
(xiv) The NGOs
Stages of warnings
Warnings are issued in four stages for the government officials. The first stage called "Alert" is issued to all concerned whenever a disturbance is detected in the Bay as per Standing Orders for Disasters (SOD) of Bangladesh. In the second stage, cyclone warnings are issued in four stages as detailed below:
(i) (a) Distant Cautionary Signal- issued if a ship might run into danger during its voyage after leaving the harbour.
(b) Distant Warning Signal issued when there is no immediate danger of the port but a ship might run into the storm after leaving the port.
(ii) (a) Local Cautionary Signal – issued when port is threatened by squally weather from tropical disturbances or nor’westers.
(b) Local Warning Signal issued when the port is threatened by a storm, but it does not appear that the danger is as yet sufficiently great to justify extreme measures of precaution. It is issued minimum 24 hours before the landfall.
(iii) Danger Signal issued when the port is likely to experience severe weather from a storm of
slight or moderate intensity. The Signal is issued minimum 18 hours before the landfall.
(iv) Great Danger Signal issued when the port is likely to experience severe weather from a storm of great intensity. The signal is issued minimum 10 hours before the landfall.
Format of the cyclone warning bulletin
Cyclone warning bulletins contain the following information:
(i) Name of the storm
(ii) Position of the storm centre
(iii) Direction and speed of movement in knots for international use and km/h for national use.
(iv) Distance of the storm centre from the ports.
(v) Maximum sustained wind within the radius of maximum wind of the disturbance.
(vi) Signals for the maritime ports.
(vii) Areas likely to be affected specifying Police Station (Thana) of subdivision as far as possible.
(vii) Approximate time of commencement of gale winds (speed more than 51 km/ h).
(viii) Storm surge height in meter and areas likely to be inundated.
(ix) Advisory for fishing boats and trawlers over North Bay and Deep Sea.
Tropical cyclone warnings for the high seas
Tropical cyclone warnings for the high seas in Bangladesh are provided from the Storm Warning Centre at Dhaka and are broadcast from the coastal radio station at Chittagong (ASC). Warnings are issued for the Bay of Bengal region north of 18o N latitude.
Warnings to ports
In accordance with international procedure, ports are warned and advised to hoist "Signals" whenever adverse weather is expected over the ports for the oceanic areas, in which it is located due to the tropical cyclone. However, regional difference exists. The warning messages normally contain information on the location, intensity, direction and speed of movement of the tropical cyclone and the expected weather over the port. The tropical cyclone signals used in Bangladesh ports along with their meaning .
Dissemination
Warnings are disseminated through high priority landline telegrams, telefax, telephone and teleprinter. In addition, warnings are also transmitted to Betar (Radio) Bangladesh, Dhaka, Chittagong, Khulna, Rangpur, Rajshahi and Sylhet for broadcast. Alert messages are broadcast four to five times a day. "Warnings" are broadcast every hour and "Danger" and "Great Danger" messages are broadcast frequently.
Dissemination of tropical cyclone warnings
(i) Telefax
(i) Telephones
(ii) Automatic Message Switching System (AMSS)
(iii) Bangladesh Betar ( Radio)
(iv) Television
(v) Through print & electronic media
(vii) W/T
(viii) Internet, by keeping information on BMD website
(http:www.bmd.gov.bd).
CLASSIFICATION OF TROPICAL CYCLONE WARNING SYSTEMS IN THE PANEL COUNTRIES
Existing classifications of low pressure systems (cyclonic disturbances) in the Panel countries are given below together with the WMO classifications.
Classification of low pressure systems (cyclonic disturbances)
presently in use by Panel countries for national purposes)
Country Type of Disturbance Corresponding Wind Speed
Bangladesh Low pressure area Less than 17 knots (less than 31 km/h)
Well marked low 17- 21 knots (31-40km/h)
Depression 22- 27 knots (41-51km/h)
Deep Depression 28- 33 knots (52-61km/h)
Cyclonic storm 34 -47 knots (62-88 km/h)
Severe cyclonic storm 48- 63knots (89-117 km/h)
Severe cyclonic storm with
a core of hurricane wind 64 – 119 knots (118-221km/h)
Super cyclonic storm 120 knots and above (222 km/h or more)
APPENDIX III
1. Tropical Cyclone Warning Centre (TCWC) - PAKISTAN
The project “ Establishment of Tropical Cyclone Warning Centre (TCWC)” is a part of the approved National Plan “Strengthening National Capacities for Multi Hazard Early Warning and Response System” Phase- I.
Under the JCOMM, WMO/ IOC Joint Commission on Oceanography and Marine Meteorology, a programme is called Global Maritime Distress and Safety System (GMDSS), under which the TCWC PMD is responsible to provide an enhanced Marine Meteorological Service to shipping community for MetArea-IX.
Presently 14 persons are posted in TCWC and the organization of TCWC is given below.
2. For analysis of TC in Arabian Sea, TCWC following tools are used in TCWC;
Surface & Upper Air Weather Charts using all possible available data
Satellite Images (FY-2) after 30 minutes interval
Radar Images
Two Young Meteorologists have recently given assignment to learn about Dvorak Method before next TC Season
Products of RSMC and JTWC are also used in the support of analysis done by TCWC
3. Forecast is based on consensus with the help of;
TCWC Products
NWFC (National Weather Forecasting Centre) located in HG PMD Islamabad also provides valuable help and guidance in decision making
Products of RSMC and JTWC are also used in the support of decision making
4. Case Studies
Case Studies of Historical Cyclones are taught in the local trainings of young and newly appointed meteorologists, and such case studies are also assigned as a research topic to the MS Thesis studies, particularly to the students who are studying MS Meteorology in COMSATS University
PMD observed following problems;
Although PMD receives regular e-mails from RSMC regarding active TC but some times it is not uploaded timely.
RSMC does not provide detailed analysis/products about the TC which enters in Western North Arabian Sea (away from Indian Coast).
Dr. Muhammad Hanif
DIRECTOR
NWFC, PMD
Pakistan Meteorological Department
APPENDIX III
APPENDIX IV
Inconsistencies between RSMC advisories and NMHSs forecasts
Current status :
Various agencies involved in monitoring and prediction of tropical cyclones (TCs) over different Ocean basins perform analysis of TCs to determine the best estimate of a TC’s position and intensity during its lifetime. This process is described as “best tracking”. However, the best tracking process is temporally inhomogeneous by construction because available data and techniques and general knowledge have changed over time. Furthermore, it is also inhomogeneous spatially, as procedures and data availability differ at each agency. Thus, the resulting best track and intensities from any Regional Specialised Meteorological Centre (RSMC) sometimes vary from those estimated by National Meteorological and Hydrological Services (NMHSs). These differences in estimates create problems for disaster managers and public to combat with the disasters due to cyclones.
Currently, the location of the centre of the system is determined based on (a) Synoptic, (b) Satellite and (c) radar observations. The satellite is the main source of locating centre of cyclonic disturbances (CDs) over the mid-oceanic region. However, the observational data from ships and buoys support the decision sometimes. It is the case when the CD is far away from the coast and not within the radar range. When the system comes closer to the coast, radar position gets maximum preference followed by the satellite. When the system is very close to coast or over the land surface, the coastal observations get the highest preference followed by radar and satellite observations.
Intensity of a CD is generally reported as the maximum sustained surface wind (MSW) over a specified time period. Operationally, the value of MSW is almost never measured. The procedure followed in estimating the intensity necessarily deals with estimation of associated MSW, estimated central pressure and pressure drop at the centre with the available observations in the region. Currently, the intensity estimation takes into consideration (a) satellite (Geostationary, Polar and scatterometer etc), (b) Radar (conventional S-band cyclone detection radar and S-band Doppler weather radar) and (c) synoptic analyses. Like the location of the system, when the system is far away from the coast and not within the radar range, satellite estimated intensity based on Dvorak’s technique (Dvorak, 1984) gets maximum weight. When the system comes closer to the coast, radar estimated intensity is considered along with satellite estimated intensity. When the system is very close to coast or over the land surface, the coastal observations get the highest preference followed by radar and satellite observations for estimating the intensity.