The legal team has described in detail the technical procedures for forecasting and warning dangerous weather phenomena such as strong winds at sea, large waves, and flooding caused by tropical depressions or strong winds. These procedures include data collection, current situation analysis, discussion and construction of forecast/warning bulletins, provision of information to relevant parties, evaluation of forecast/warning quality, and determination of bulletin issuance frequency.
Scope of application
These procedures apply to the national meteorological and hydrological forecasting and warning system as well as organizations and individuals outside this system.
Key points
- Collection and processing of data from various sources.
- Analysis of the current situation to identify areas with strong winds, large waves, and flooding.
- Discussion of forecast results with experts to ensure the reliability of the information.
- Construction and issuance of forecast/warning bulletins in accordance with legal provisions.
- Provision of information to relevant parties such as local authorities, fishermen, tourists.
- Evaluation of forecast/warning quality after sufficient observational data is available.
- Determination of bulletin issuance frequency and timing based on actual needs.
🌐 Social impact of this document
- Helps minimize casualties and property damage caused by dangerous weather phenomena.
- Provides accurate and timely information to the community to take preventive measures.
- Enhances the forecasting and warning capacity of the national meteorological and hydrological system.
❓ Frequently asked questions
To which entities does this procedure apply?
It applies to both the national meteorological and hydrological forecasting and warning system and organizations and individuals outside this system.
What data must be collected to forecast strong winds at sea?
It includes wind speed measurements, air pressure, wave heights, water levels from meteorological marine stations and other sources such as weather maps.
Is it necessary to discuss with experts when constructing forecast bulletins?
Yes, discussions help analyze the reliability of forecast results and make final decisions to ensure accuracy.
Full text
CIRCULAR
Regulations on the technical forecasting and warning procedures for meteorological and hydrological phenomena
Pursuant to the Law on Meteorology and Hydrology dated November 23, 2015;
Pursuant to Decree No. 38/2016/NĐ-CP dated May 15, 2016 of the Government detailing certain provisions of the Law on Meteorology and Hydrology; Decree No. 48/2020/NĐ-CP dated April 15, 2020 of the Government amending and supplementing certain articles of Decree No. 38/2016/NĐ-CP dated May 15, 2016 of the Government detailing certain provisions of the Law on Meteorology and Hydrology;
Pursuant to Decree No. 68/2022/NĐ-CP dated September 22, 2022 of the Government stipulating the functions, tasks, powers, and organizational structure of the Ministry of Natural Resources and Environment;
Pursuant to Decision No. 18/2021/QĐ-TTg dated April 22, 2021 of the Prime Minister on forecasting, warning, transmitting disaster information and disaster risk levels;
At the proposal of the Director General of the National Centre for Hydro-meteorological Forecasting, the Head of the Science and Technology Department and the Head of the Legal Department;
The Minister of Natural Resources and Environment promulgates this Circular stipulating the Technical Forecasting and Warning Procedures for Dangerous Meteorological and Hydrological Phenomena.
PART I
GENERAL PROVISIONS
Article 1. Scope of Regulation
This Circular stipulates the Technical Forecasting and Warning Procedures for dangerous meteorological and hydrological phenomena, including: Tropical depression, typhoon; heavy rain; flood, inundation; flash flood, landslides, subsidence caused by floods or runoff; cold air, severe cold, extreme cold, frost, frostbite, ice, salt fog; heatwave; drought, landslides, subsidence caused by drought; salinity intrusion; thunderstorm, tornado, lightning, hail; strong wind over sea, large waves, high tide, spring tide, fog.
Article 2. Applicability
1. National meteorological and hydrological forecasting and warning system.
2. State management agencies for meteorology and hydrology; organizations and individuals licensed by the Ministry of Natural Resources and Environment or People's Committees of provinces and centrally governed cities to operate meteorological and hydrological forecasting and warning activities.
Article 3. Explanation of Terms
In this Circular, the following terms are understood as follows:
1. Dangerous meteorological and hydrological phenomena are abnormal states and developments of weather, hydrological, and marine factors that may cause casualties, property damage, environmental impact, living conditions, infrastructure, and socio-economic activities.
2. Forecasting and warning plan is a specific method for analyzing, calculating, forecasting, and warning about meteorological and hydrological factors or phenomena at a location or area.
3. Supplementing forecast bulletin means increasing the number of forecast bulletins beyond the prescribed requirements to adjust and refine the content based on the latest information to ensure timely response and reliability of forecasts.
4. Forecast quality assessment involves activities aimed at determining the completeness and timeliness of forecast bulletins and the reliability of forecasted factors and phenomena.
5. Cold air is a hazardous weather phenomenon where cold air masses from the north invade Vietnam, causing existing wind systems in the north to fundamentally change into northerly winds and increased atmospheric pressure.
6. Severe cold is a special type of winter weather when the average daily air temperature drops below 15 degrees Celsius.
7. Frost is a phenomenon where water vapor rises and condenses into tiny ice particles upon encountering cold air at the surface.
8. Thunderstorm is a weather phenomenon characterized by electrical discharge from clouds, manifesting as lightning or thunder. Thunderstorms typically occur in convective clouds (Cb clouds) and are accompanied by rain, showers, hail, and strong gusts of wind.
9. Spring tide is a phenomenon where tidal levels rise above the warning level for water levels in the region. High spring tides can cause flooding in low-lying coastal areas, river mouths, and regions outside embankments, increasing the risk of landslides, dike breaches, and salinity intrusion, especially when combined with high water levels and large waves caused by typhoons, tropical depressions, and strong monsoon winds affecting the region.
Chapter II
TECHNICAL FORECASTING AND WARNING PROCEDURES FOR DANGEROUS METEOROLOGICAL AND HYDROLOGICAL PHENOMENA
Section 1. TECHNICAL PROCEDURE FOR FORECASTING AND WARNING OF TROPICAL LOW PRESSURE SYSTEMS AND STORMS
Article 4. Content of Forecasting and Warning of Tropical Low Pressure Systems and Storms
1. Position of the center of the tropical low pressure system, storm.
2. The highest wind speed level and the highest gust wind speed level in the area near the center of the tropical low pressure system, storm.
3. Radius of areas with wind speeds above level 6, level 10, the 70% probability circle around the center of the tropical low pressure system, storm that may enter; direction and speed of movement.
4. Impact of the tropical low pressure system, storm: Strong winds, large waves, sea conditions, heavy rain, flooding, coastal inundation, and other natural disasters.
5. Level of disaster risk caused by the tropical low pressure system, storm.
Article 5. Technical Procedure for Forecasting and Warning of Tropical Low Pressure Systems and Storms
1. Collection and processing of various types of information and data
a) Data on tropical low pressure systems and storms from weather maps;
b) Enhanced observation data when tropical low pressure systems and storms have the potential to affect the mainland;
c) Data on tropical low pressure systems and storms through remote sensing information;
d) Data on tropical low pressure systems and storms from numerical forecast products;
đ) Data on tropical low pressure systems and storms from international storm forecasting centers;
e) Figures and information on the current status of objects potentially affected by tropical low pressure systems and storms and any damages (if any) caused by their impact.
2. Analysis and evaluation of the current situation
a) Determine the position of the center of the tropical low pressure system, storm based on the data and information collected under Clause 1 of Article 5 of this Circular;
b) Determine the highest wind speed level and gust wind speed level in the area near the center of the tropical low pressure system, storm based on the data and information collected under Clause 1 of Article 5 of this Circular;
c) Determine the radius of areas with wind speeds above level 6, level 10 based on the data and information collected under Clause 1 of Article 5 of this Circular;
d) Determine the impact of the tropical low pressure system, storm on the figures collected according to Clause 1 of Article 5 of this Circular;
đ) Determine the development regarding direction and speed of movement, highest wind speed level, gust wind speed level in the area near the center of the tropical low pressure system, storm within 6 to 12 hours prior.
3. Implementation of forecasting and warning plans
a) Plans used in forecasting and warning of tropical low pressure systems and storms at the national meteorological and hydrological forecasting and warning system: Plan based on statistical analysis method; plan based on numerical model method (individual and combined); plan based on the experience analysis of forecasters based on statistical forecast results, numerical model forecast results, and synthesis of results from information of international storm forecasting centers; plan based on other methods;
b) Based on specific conditions, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the use of forecasting and warning plans as appropriate.
4. Discussion on Forecasting and Warning
a) Analyze and evaluate the reliability of forecasting and warning results using different methods, the results of recent forecasting and warning bulletins;
b) Synthesize initial forecasting and warning results from different methods and the opinions of forecasters;
c) The person responsible for issuing the bulletin selects and presents the final forecasting conclusion ensuring reliability within the forecast and warning period.
5. Construction of Forecasting and Warning Bulletins
a) The national meteorological and hydrological forecasting and warning system constructs and issues forecasting and warning bulletins on tropical low pressure systems and storms in accordance with Articles 8, 9, 10, and 11 of Decision No. 18/2021/QĐ-TTg dated April 22, 2021;
b) Based on actual requirements, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the content of the bulletin as appropriate.
6. Provision of Forecasting and Warning Bulletins
a) The national meteorological and hydrological forecasting and warning system provides forecasting and warning bulletins on tropical low pressure systems and storms in accordance with Article 34 of Decision No. 18/2021/QĐ-TTg;
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the list of addresses to be provided with bulletins in accordance with actual requirements.
7. Supplementing Forecasting and Warning Bulletins In cases where complex developments of tropical low pressure systems and storms are detected, supplementary forecasting and warning bulletins on tropical low pressure systems and storms outside those issued according to Article 6 of this Circular shall be supplemented. The supplementation of bulletins shall be carried out in accordance with Clauses 1, 2, 3, 4, 5, and 6 of this Article.
8. Evaluation of Forecasting and Warning Quality
a) National meteorological and hydrological forecasting and warning system: Evaluate the implementation of Clauses 1, 2, 3, 4, 5, 6, and 7 of this Article; evaluate the completeness and timeliness of forecasting and warning of tropical low pressure systems and storms in accordance with Articles 8, 9, 10, 11, 12, 13, and Clause 1 of Article 35 of Decision No. 18/2021/QĐ-TTg; evaluate the quality of forecasting and warning bulletins on tropical low pressure systems and storms in accordance with Section 2.8 of the National Technical Regulation on Forecasting and Warning of Storms and Tropical Low Pressure Systems (QCVN 68:2020/BTNMT) issued by Circular No. 18/2020/TT-BTNMT dated December 30, 2020 of the Minister of Natural Resources and Environment and Article 18 of Circular No. 41/2017/TT-BTNMT dated October 23, 2017 of the Minister of Natural Resources and Environment stipulating technical assessment of forecasting and warning quality (hereinafter referred to as Circular No. 41/2017/TT-BTNMT). The evaluation of the quality of forecasting and warning bulletins shall be conducted after sufficient observational data has been collected within the forecast period of the bulletin;
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system must comply with current regulations on evaluating forecasting quality.
Article 6. Frequency and time of issuing tropical low pressure forecast and warning bulletins, typhoon warnings
1. The national weather forecasting and warning system shall issue tropical low pressure forecast and warning bulletins, typhoon warnings at frequencies and times as prescribed in Article 13 of Decision No. 18/2021/QĐ-TTg.
2. Organizations and individuals not belonging to the national weather forecasting and warning system shall be responsible for specifying the frequency and time of issuing forecast and warning bulletins in accordance with actual requirements.
Section 2. TECHNICAL PROCEDURES FOR LARGE RAINFALL FORECASTING AND WARNING
Article 7. Content of large rainfall forecasts and warnings
1. Area of heavy rain.
2. Time of heavy rain.
3. Rainfall amount and probability of occurrence.
4. Level of natural disaster risk due to heavy rain.
Article 8. Technical procedures for large rainfall forecasting and warning
1. Collection and processing of various types of information and data
a) Weather data, including surface observations and radio-sounding data;
b) Meteorological satellite data;
c) Weather radar data;
d) Numerical model data;
đ) Climatological statistics data;
e) Infrastructure and socio-economic data in areas potentially affected by heavy rain.
2. Analysis and evaluation of the current situation
a) Analysis and evaluation of current weather patterns and related characteristics causing heavy rain: Synoptic pattern analysis; analysis of large-scale atmospheric circulation characteristics; meteorological satellite data analysis; weather radar data analysis; dynamic characteristic analysis; thermal characteristic analysis;
b) Determination of past heavy rain development and evaluation of current heavy rain regarding rainfall duration, area, intensity, amount, and probability of occurrence.
3. Implementation of forecasting and warning plans
a) Forecasting and warning methods used in the national weather forecasting and warning system for heavy rain: Methods based on synoptic, expert, and statistical approaches; methods based on satellite and radar data analysis and automatic rainfall measurement; numerical model-based methods; analog method; combined methods using multiple approaches;
b) Based on specific conditions, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the use of forecasting and warning plans as appropriate.
4. Discussion on Forecasting and Warning
a) Evaluation of the reliability of forecast results from different methods and recent forecast bulletins;
b) Compilation of initial forecast results from various methods and issuance of forecasters' assessments;
c) The person responsible for issuing the bulletin selects and issues the final forecast conclusion ensuring reliability within the forecast period.
5. Construction of Forecasting and Warning Bulletins
a) The national weather forecasting and warning system shall develop and issue heavy rain forecast and warning bulletins in accordance with Clause 1 of Article 14, Clause 1 and Clause 2 of Article 15, and Clause 1 of Article 16 of Decision No. 18/2021/QĐ-TTg;
b) Based on actual requirements, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the content of the bulletin as appropriate.
6. Provision of Forecasting and Warning Bulletins
a) The national weather forecasting and warning system shall provide heavy rain forecast and warning bulletins in accordance with Article 34 of Decision No. 18/2021/QĐ-TTg;
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the list of addresses to be provided with bulletins in accordance with actual requirements.
7. Supplementing forecast and warning bulletins In cases of exceptionally heavy or extremely dangerous rain, additional heavy rain forecast and warning bulletins shall be issued beyond those stipulated in Article 9 of this Circular. The supplementation of bulletins shall be carried out in accordance with Clauses 1, 2, 3, 4, 5, and 6 of this Article.
8. Evaluation of Forecasting and Warning Quality
a) National weather forecasting and warning system: Evaluation of full implementation as specified in Clauses 1, 2, 3, 4, 5, 6, and 7 of this Article; assessment of the completeness and timeliness of heavy rain forecasting and warning as stipulated in Clause 1 of Article 14, Clause 1 and Clause 2 of Article 15, and Clause 1 of Article 35 of Decision No. 18/2021/QĐ-TTg; assessment of the quality of heavy rain forecast and warning bulletins as stipulated in Article 19 of Circular No. 41/2017/TT-BTNMT. The quality assessment of forecast and warning bulletins shall be conducted after sufficient observation data has been collected within the forecast period.
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system must comply with current regulations on evaluating forecasting quality.
Article 9. Frequency and time for issuing flood warning bulletins
1. The national weather and hydrological forecasting and warning system shall issue flood warning bulletins at frequencies and times as prescribed in Clause 1 of Article 16 of Decision No. 18/2021/QĐ-TTg.
2. Organizations and individuals not belonging to the national weather and hydrological forecasting and warning system shall independently determine the frequency and time for issuing flood warning bulletins in accordance with actual conditions.
Section 3. TECHNICAL PROCEDURES FOR FLOOD AND FLOODED AREA FORECASTING AND WARNING
Article 10. Content of flood and flooded area forecasting and warning
1. Flood water level.
2. Flood alert levels.
3. Risk of flooding and other natural disasters accompanying it.
4. Degree of natural disaster risk due to floods and flooding.
Article 11. Technical procedures for flood and flooded area forecasting and warning
1. Collection and processing of various types of information and data
a) Collecting rainfall observation data, water levels, flow rates from meteorological and hydrological stations in river basins, operational data of hydropower reservoirs, irrigation reservoirs, and meteorological and hydrological data of international reservoirs related to the forecasted area (if applicable);
b) Continuously updating observation data;
c) Rainfall forecast bulletins serving hydrology.
2. Analysis and evaluation of the current situation
a) Analyzing the minimum flood trend over the past 12 hours;
b) Analyzing and identifying the cause of flooding (if applicable);
c) Analyzing the possibility of other accompanying natural disasters occurring.
3. Implementation of forecasting and warning plans
a) Forecasting and warning methods used in the national weather and hydrological forecasting and warning system for floods and flooding: Methods based on rainfall-runoff relationship; methods based on water level and flow rate relationships between upstream and downstream stations (flow discharge from upstream reservoirs) on the same river slope or basin; methods based on mathematical models (regression models; parameterized hydrological models; distributed parameter hydrological models; reservoir regulation models; hydraulic and flooding models); other methods;
b) Based on specific conditions, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the use of forecasting and warning plans as appropriate.
4. Discussion on Forecasting and Warning
a) Evaluating the reliability of forecasting results using different methods in recent forecast bulletins;
b) Synthesizing forecasting results from various methods and the opinions of forecasters;
c) The person responsible for issuing the bulletin selects and issues the final forecast conclusion ensuring reliability within the forecast period.
5. Construction of Forecasting and Warning Bulletins
a) The national weather and hydrological forecasting and warning system shall establish and issue flood and flooding forecasting and warning bulletins in accordance with Clauses 2, 3, 4, and 5 of Article 14 and Clauses 3, 4, and 5 of Article 15 of Decision No. 18/2021/QĐ-TTg;
b) Based on actual requirements, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the content of the bulletin as appropriate.
6. Provision of Forecasting and Warning Bulletins
a) The national weather and hydrological forecasting and warning system shall provide flood and flooding forecasting and warning bulletins in accordance with Article 34 of Decision No. 18/2021/QĐ-TTg;
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the list of addresses to be provided with bulletins in accordance with actual requirements.
7. Supplementing forecast and warning bulletins In cases where floods develop rapidly and complexly, additional flood and flooding forecast and warning bulletins shall be issued outside those issued according to the provisions of Article 12 of this Circular. The supplementation of bulletins shall be carried out in accordance with the provisions of Clauses 1, 2, 3, 4, 5, and 6 of this Article.
8. Evaluation of Forecasting and Warning Quality
a) National weather and hydrological forecasting and warning system: Assessing the implementation of Clause 1, Clause 2, Clause 3, Clause 4, Clause 5, Clause 6, and Clause 7 of this Article; assessing the completeness and timeliness of flood and flooding forecasting and warning as prescribed in Clauses 2, 3, 4, and 5 of Article 14, Clauses 3, 4, and 5 of Article 15, and Clause 1 of Article 35 of Decision No. 18/2021/QĐ-TTg; assessing the quality of flood and flooding forecasting and warning bulletins as prescribed in Section 2.12 of the National Technical Regulation on Flood Forecasting and Warning (QCVN 18:2019/BTNMT) issued by Circular No. 22/2019/TT-BTNMT dated December 25, 2019 of the Minister of Natural Resources and Environment and Articles 6, 21, 22, and 23 of Circular No. 42/2017/TT-BTNMT dated October 23, 2017 of the Minister of Natural Resources and Environment stipulating technical evaluation of hydrological forecasting and warning quality (hereinafter referred to as Circular No. 42/2017/TT-BTNMT). The assessment of the quality of flood and flooding forecasting and warning bulletins shall be conducted after sufficient observation data has been collected within the forecast period of the bulletin.
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system must comply with current regulations on evaluating forecasting quality.
Article 12. Frequency and time for issuing flood and inundation forecast bulletins
1. The national meteorological and hydrological forecasting and warning system shall issue flood and inundation forecast and warning bulletins at frequencies and times as prescribed in Clauses 2, 3, 4, and 5 of Article 16 of Decision No. 18/2021/QĐ-TTg.
2. Organizations and individuals not belonging to the national weather forecasting and warning system shall be responsible for specifying the frequency and time of issuing forecast and warning bulletins in accordance with actual requirements.
Section 4. TECHNICAL PROCEDURES FOR FLOOD, LANDSLIDE, AND GROUND SUBSIDENCE WARNINGS CAUSED BY RAINFALL OR WATER FLOW
Article 13. Content of warnings for flash floods, landslides, and ground subsidence caused by rainfall or water flow
1. Rainfall volume during the period of flash flood, landslide, and ground subsidence warning.
2. Time period with risk of flash floods, landslides, and ground subsidence caused by rainfall or water flow.
3. Areas at risk of flash floods, landslides, and ground subsidence caused by rainfall or water flow.
4. Level of natural disaster risk due to flash floods, landslides, and ground subsidence caused by rainfall or water flow.
Article 14. Technical procedures for warnings of flash floods, landslides, and ground subsidence caused by rainfall or water flow
1. Collecting and processing various types of information and data
a) Data from rain gauges, water levels, operation data of reservoirs or flood prevention and control works in the warning area and adjacent areas;
b) Rainfall forecast data from satellite products, radar, and numerical models;
c) Warning information on flash floods, landslides, and ground subsidence caused by rainfall or water flow from domestic and international weather and disaster warning organizations (if available).
2. Analysis and evaluation of the current situation
a) Analyze the minimum rainfall trend over the past six hours;
b) Analyze the upstream flood trend in the warning area;
c) Determine the current operational status of reservoirs in the warning area or upstream (if applicable);
d) Assess the likelihood of rainfall leading to flash floods, landslides, and ground subsidence during the warning period.
3. Implement warning plans
a) Warning plans used in the national meteorological and hydrological forecasting and warning system for flash floods, landslides, and ground subsidence caused by rainfall or water flow include statistical analysis-based plans, spatial data analysis plans based on factors causing flash floods, landslides, and ground subsidence, numerical modeling methods, and other methods;
b) Based on specific conditions, organizations and individuals not part of the national meteorological and hydrological forecasting and warning system shall independently determine the use of warning plans as appropriate.
4. Discuss warning The person responsible for issuing the bulletin shall quickly discuss with forecasters on duty before releasing the bulletin.
5. Develop warning bulletins
a) The national meteorological and hydrological forecasting and warning system shall develop and issue flash flood, landslide, and ground subsidence warning bulletins caused by rainfall or water flow according to Clause 6 of Article 14 and Clause 6 of Article 15 of Decision No. 18/2021/QĐ-TTg;
b) Based on actual requirements, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the content of the bulletin as appropriate.
6. Provide warning bulletins
a) The national meteorological and hydrological forecasting and warning system shall provide flash flood, landslide, and ground subsidence warning bulletins caused by rainfall or water flow according to Article 34 of Decision No. 18/2021/QĐ-TTg;
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the list of addresses to be provided with bulletins in accordance with actual requirements.
7. Supplement warning bulletins In cases where unusual developments of flash floods, landslides, and ground subsidence caused by rainfall or water flow are detected, additional warning bulletins for flash floods, landslides, and ground subsidence caused by rainfall or water flow shall be issued outside those issued according to Article 15 of this Circular. The supplementation of bulletins shall be carried out according to Clauses 1, 2, 3, 4, 5, and 6 of this Article.
8. Evaluate the quality of warnings
a) The national meteorological and hydrological forecasting and warning system: Evaluate the implementation of Clauses 1, 2, 3, 4, 5, 6, and 7 of this Article; evaluate the completeness and timeliness of warnings for flash floods, landslides, and ground subsidence caused by rainfall or water flow as prescribed in Clause 6 of Article 14, Clause 6 of Article 15, and Clause 1 of Article 35 of Decision No. 18/2021/QĐ-TTg; evaluate the quality of flash flood, landslide, and ground subsidence warning bulletins caused by rainfall or water flow as prescribed in Article 13 of Circular No. 42/2017/TT-BTNMT. The evaluation of the quality of flash flood, landslide, and ground subsidence warning bulletins caused by rainfall or water flow shall be conducted after sufficient observation data has been collected within the warning bulletin's timeframe.
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system must comply with current regulations on evaluating forecasting quality.
Article 15. Frequency and Time for Issuing Flash Flood, Landslide, and Ground Subsidence Warning Bulletins Due to Rainfall or Runoff
1. The national weather and hydrological forecasting and warning system shall issue flash flood, landslide, and ground subsidence warning bulletins due to rainfall or runoff at frequencies and times as prescribed in Clause 6 of Article 16 of Decision No. 18/2021/QĐ-TTg.
2. Organizations and individuals not belonging to the national weather forecasting and warning system shall be responsible for specifying the frequency and time of issuing forecast and warning bulletins in accordance with actual requirements.
Section 5. TECHNICAL PROCEDURES FOR FORECASTING AND WARNING OF COLD AIR, SEVERE COLD, EXTREME COLD, ICE, AND SALT FOG
Article 16. Content of Cold Air Forecasting and Warning, Severe Cold, Extreme Cold, Ice, and Salt Fog
1. Lowest temperature.
2. Strong winds and gusts on land.
3. Strong winds and gusts, large waves at sea.
4. Possibility of severe cold, extreme cold, ice, and salt fog occurrence (area, time).
5. Level of natural disaster risk due to extreme cold and salt fog.
Article 17. Technical Procedures for Forecasting and Warning of Cold Air, Severe Cold, Extreme Cold, Ice, and Salt Fog
1. Collection and processing of various types of information and data
a) Data on atmospheric patterns affected by cold air on weather maps;
b) Surface meteorological observation data and marine data when cold air affects Vietnam;
c) Forecast data on cold air through numerical products;
d) Satellite, radar, and remote sensing observation data.
2. Analysis and evaluation of the current situation
a) Evaluate and analyze collected data to identify atmospheric patterns affected by cold air and those that intensify or weaken cold air;
b) Determine the intensity of cold air based on the lowest temperature, strong winds at sea, and the possibility of severe cold, extreme cold, ice, and salt fog occurrence;
c) Determine the range of cold air, severe cold, extreme cold, ice, and salt fog;
d) Determine the evolution of cold air based on its intensity and the range of occurrence over the past 24 to 48 hours;
3. Implementation of forecasting and warning plans
a) Forecast and warning methods for cold air, severe cold, extreme cold, ice, and salt fog used in the national weather and hydrological forecasting and warning system: Statistical method-based approach; numerical model-based approach (single and combined); analysis of forecasters' experience based on statistical forecasts and numerical model forecasts; other methods (if applicable);
b) Based on specific conditions, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the use of forecasting and warning plans as appropriate.
4. Discussion on Forecasting and Warning
a) Evaluating the reliability of forecasting results using different methods in recent forecast bulletins;
b) Synthesizing forecasting results from various methods and the opinions of forecasters;
c) The person responsible for issuing the bulletin selects and issues the final forecast conclusion ensuring reliability within the forecast period.
5. Construction of Forecasting and Warning Bulletins
a) National weather and hydrological forecasting and warning system: Develop and issue cold wave and salt fog warning bulletins as prescribed in Clause 2 of Article 23 and Clause 2 of Article 24 of Decision No. 18/2021/QĐ-TTg; develop and issue cold air and severe cold, ice warning bulletins including: Northeast monsoon bulletin issued when the Northeast monsoon has moderate strength or higher; Northeast monsoon and cold wave bulletin issued when the Northeast monsoon has moderate strength or higher and the potential for widespread severe cold; enhanced cold air bulletin issued when enhanced cold air has moderate strength or higher; enhanced cold air and cold wave bulletin issued when enhanced cold air has moderate strength or higher and the potential for widespread severe cold; evolution of cold air over the past period to the present regarding intensity, direction, speed of movement, and weather changes (wind speed, temperature, rain); forecast of cold air movement, impact time, degree of impact, and impact range within 24 to 48 hours ahead; forecast of weather evolution regarding the lowest temperature, strong winds, and gusts in a specific inland area and strong winds, gusts, and large waves in a specific sea area (if applicable), possibility of severe cold, extreme cold, ice, salt fog, snow, thunderstorms, lightning, tornadoes, hail, heavy rain, and their impact on the environment, living conditions, infrastructure, economic and social activities; time of bulletin issuance, time of subsequent bulletin issuance; name and signature of the person responsible for issuing the bulletin;
b) Based on actual requirements, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the content of the bulletin as appropriate.
6. Provision of Forecasting and Warning Bulletins
a) The national weather and hydrological forecasting and warning system provides cold air, severe cold, extreme cold, ice, and salt fog forecasting and warning bulletins as prescribed in Article 34 of Decision No. 18/2021/QĐ-TTg;
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the list of addresses to be provided with bulletins in accordance with actual requirements.
7. Supplemental Bulletins In case of abnormal developments in cold air, severe cold, extreme cold, ice, and salt fog situations, supplemental bulletins shall be issued outside the regular bulletins as prescribed in Article 18 of this Circular. The issuance of supplemental bulletins shall be carried out according to the provisions of Clauses 1, 2, 3, 4, 5, and 6 of this Article.
8. Evaluation of Forecasting and Warning Quality
a) National weather and hydrological forecasting and warning system: Assess compliance with Clauses 1, 2, 3, 4, 5, 6, and 7 of this Article; assess the completeness and timeliness of cold air, severe cold, extreme cold, ice, and salt fog forecasting and warning as prescribed in Clause 5 of this Article and Clause 2 of Article 23, Clause 2 of Article 24, and Clause 1 of Article 35 of Decision No. 18/2021/QĐ-TTg; assess the quality of cold air, severe cold, extreme cold, ice, and salt fog forecasting and warning bulletins as prescribed in Article 20 of Circular No. 41/2017/TT-BTNMT. Quality assessment of forecasting and warning bulletins shall be conducted after sufficient observational data is available within the forecast period.
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system must comply with current regulations on evaluating forecasting quality.
Article 18. Frequency and time for issuing cold air and severe cold, very cold weather, frost, and salt fog bulletins
1. National weather forecasting and warning system
a) Issuing forecasts and warnings of very cold weather and salt fog at frequencies and times as prescribed in Clause 2, Article 25 of Decision No. 18/2021/QĐ-TTg;
b) Issuing the first forecast and warning bulletin on cold air, severe cold, and frost when the possibility of their occurrence in the forecast and warning area is detected; subsequent forecast and warning bulletins on cold air, severe cold, and frost shall be issued daily at four times: 03:30, 09:30, 15:30, and 21:30.
2. Organizations and individuals not belonging to the national weather forecasting and warning system shall be responsible for specifying the frequency and time of issuing forecast and warning bulletins in accordance with actual requirements.
Section 6. TECHNICAL PROCEDURES FOR FORECASTING AND WARNING HOT WEATHER
Article 19. Content of hot weather forecasts and warnings
1. Highest temperature.
2. Lowest relative humidity.
3. Duration of hot weather during the day.
4. Affected areas, time of appearance, and end time.
5. Level of disaster risk due to hot weather.
Article 20. Technical procedures for forecasting and warning hot weather
1. Collection and processing of various types of information and data
a) Data on weather patterns causing hot weather on weather maps;
b) Observation data on temperature and relative humidity;
c) Satellite data;
d) Data on hot weather from numerical forecast products;
đ) Observation data and information on objects potentially affected by hot weather and damages (if any) caused by hot weather.
2. Analysis and evaluation of the current situation
a) Evaluating and analyzing collected data to identify the activity of weather patterns causing hot weather such as: Western low-pressure ridge; compressed trough; tropical high-pressure ridge; low-level southwest monsoon combined with high-pressure ridge aloft;
b) Determining the intensity of hot weather through the highest temperature and lowest relative humidity in a day;
c) Determining the scope of hot weather;
d) Determining the development of hot weather based on its intensity and scope occurring over the previous 24 to 48 hours.
3. Implementation of forecasting and warning plans
a) Forecast and warning options used in the national weather forecasting and warning system: Statistical method-based option using current, past observation information, and future forecasts; numerical model-based option (single and composite); experience analysis-based option by forecasters based on statistical forecast results and numerical model forecasts; other method-based options;
b) Based on specific conditions, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the use of forecasting and warning plans as appropriate.
4. Discussion on Forecasting and Warning
a) Evaluation of the reliability of forecast results from different methods and recent forecast bulletins;
b) Synthesizing forecasting results from various methods and the opinions of forecasters;
c) The person responsible for issuing the bulletin selects and issues the final forecast conclusion ensuring reliability within the forecast period.
5. Construction of Forecasting and Warning Bulletins
a) The national weather forecasting and warning system establishes and issues hot weather forecast and warning bulletins according to Clause 1, Article 17 and Clauses 1 and 2, Article 18 of Decision No. 18/2021/QĐ-TTg;
b) Based on actual requirements, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the content of the bulletin as appropriate.
6. Provision of Forecasting and Warning Bulletins
a) The national weather forecasting and warning system provides hot weather forecast and warning bulletins according to Article 34 of Decision No. 18/2021/QĐ-TTg;
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the list of addresses to be provided with bulletins in accordance with actual requirements.
7. Supplementing forecast and warning bulletins In cases of particularly severe and prolonged hot weather, supplementary forecast and warning bulletins shall be issued outside those issued according to Article 21 of this Circular. The supplementation of bulletins shall be carried out according to Clauses 1, 2, 3, 4, 5, and 6 of this Article.
8. Evaluation of Forecasting and Warning Quality
a) The national weather forecasting and warning system: Evaluates the implementation of Clause 1, Clause 2, Clause 3, Clause 4, Clause 5, Clause 6, and Clause 7 of this Article; evaluates the completeness and timeliness of hot weather forecasts and warnings according to Clause 1, Article 17, Clause 1, Clause 2, Article 18, and Clause 1, Article 35 of Decision No. 18/2021/QĐ-TTg; evaluates the quality of hot weather forecast and warning bulletins according to Clause 2, Article 21 of Circular No. 41/2017/TT-BTNMT. The evaluation of bulletin quality shall be conducted after sufficient observation data has been collected within the forecast period.
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system must comply with current regulations on evaluating forecasting quality.
Article 21. Frequency and Time for Issuing Heatwave Forecast and Warning Bulletins
1. The national weather and hydrological forecast and warning system shall issue heatwave forecast and warning bulletins at the frequency and time as prescribed in Clause 1 of Article 19 of Decision No. 18/2021/QĐ-TTg.
2. Organizations and individuals not belonging to the national weather forecasting and warning system shall be responsible for specifying the frequency and time of issuing forecast and warning bulletins in accordance with actual requirements.
Section 7. TECHNICAL PROCEDURES FOR FORECASTING AND WARNING OF DROUGHT AND LANDSLIDES AND SUBSIDENCE CAUSED BY DROUGHT
Article 22. Content of Drought and Landslide and Subsidence Caused by Drought Forecast and Warning
1. Shortage of total rainfall in the forecast and warning area.
2. Shortage of surface water volume in the forecast and warning area.
3. Potential for landslide and subsidence caused by drought.
4. Level of disaster risk due to drought and landslide and subsidence caused by drought.
Article 23. Technical Procedures for Forecasting and Warning of Drought and Landslide and Subsidence Caused by Drought
1. Collection and processing of various types of information and data
a) Rainfall observation data, evaporation, humidity, water level, flow rate (if available);
b) Rainfall forecast data from global and regional models;
c) Information and data on reservoir operation and hydraulic works (if available) in the forecast area and adjacent areas;
d) Statistical characteristics of total rainfall and surface water volume in the forecast area and adjacent areas;
đ) Rainfall forecast bulletin for drought forecasting purposes.
2. Analysis and evaluation of the current situation
a) Meteorological trends: Analysis and evaluation of the shortage of total rainfall in the forecast area compared to the average value over many years during the same period or a similar past year;
b) Hydrological trends: Analysis of water level and flow rate (if available) on rivers within the watershed and forecast area; assessment of the impact of reservoir operations on river flows within the watershed and forecast area; analysis and evaluation of changes in total water volume in the watershed and forecast area over the last 10 days, one month, three months, six months, or a requested time period.
3. Implementation of forecasting and warning plans
a) Forecast and warning methods used in the national weather and hydrological forecast and warning system for drought and landslide and subsidence caused by drought (if applicable): Methods based on statistical methods; methods based on numerical model approaches (individual and combined); comprehensive methods based on forecasters' experience analysis; methods based on other approaches;
b) Based on specific conditions, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the use of forecasting and warning plans as appropriate.
4. Discussion on Forecasting and Warning
a) Evaluating the reliability of forecasting results using different methods in recent forecast bulletins;
b) Synthesis of forecast and warning results from different methods and forecasters' assessments;
c) The person responsible for issuing the bulletin selects and issues the final forecast conclusion ensuring reliability within the forecast period.
5. Construction of Forecasting and Warning Bulletins
a) The national weather and hydrological forecast and warning system shall establish and issue drought and landslide and subsidence caused by drought forecast and warning bulletins according to Clause 2 of Article 17, Clause 3 of Article 18 of Decision No. 18/2021/QĐ-TTg;
b) Based on actual requirements, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the content of the bulletin as appropriate.
6. Provision of Forecasting and Warning Bulletins
a) The national weather and hydrological forecast and warning system shall provide drought and landslide and subsidence caused by drought forecast and warning bulletins according to Article 34 of Decision No. 18/2021/QĐ-TTg;
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the list of addresses to be provided with bulletins in accordance with actual requirements.
7. Supplemental Bulletins In cases where drought and landslide and subsidence caused by drought show complex developments requiring additional forecast and warning bulletins beyond those issued according to Article 24 of this Circular, such supplemental bulletins shall be issued in accordance with Clauses 1, 2, 3, 4, 5, and 6 of this Article.
8. Evaluation of Forecasting and Warning Quality
a) National weather and hydrological forecast and warning system: Evaluation of compliance with Clauses 1, 2, 3, 4, 5, 6, and 7 of this Article; evaluation of the completeness and timeliness of drought and landslide and subsidence caused by drought forecast and warning as prescribed in Clause 2 of Article 17, Clause 3 of Article 18, and Clause 1 of Article 35 of Decision No. 18/2021/QĐ-TTg; evaluation of the quality of drought and landslide and subsidence caused by drought forecast and warning bulletins as prescribed in Article 24 of Circular No. 42/2017/TT-BTNMT. The quality evaluation of drought and landslide and subsidence caused by drought forecast and warning bulletins shall be conducted after sufficient observation data has been collected within the forecast bulletin's timeframe.
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system must comply with current regulations on evaluating forecasting quality.
Article 24. Frequency and Time for Issuing Drought Forecast and Warning Bulletins on Landslides and Ground Subsidence Caused by Drought
1. The National Meteorological and Hydrological Forecasting and Warning System shall issue drought forecast and warning bulletins on landslides and ground subsidence caused by drought (if any) at the frequency and time specified in Clause 2 of Article 19 of Decision No. 18/2021/QĐ-TTg.
2. Organizations and individuals not belonging to the national weather forecasting and warning system shall be responsible for specifying the frequency and time of issuing forecast and warning bulletins in accordance with actual requirements.
Section 8. TECHNICAL PROCEDURE FOR FORECASTING AND WARNING SALINITY INTRUSION
Article 25. Content of Salinity Intrusion Forecast and Warning
1. Highest salinity level and time of occurrence at various locations.
2. Scope and duration affected by salinity levels of 4‰ or 1‰.
3. Distance affected by salinity levels of 4‰ or 1‰ from the main river mouth.
4. Level of natural disaster risk due to salinity intrusion.
Article 26. Technical Procedure for Forecasting and Warning Salinity Intrusion
1. Collection and processing of various types of information and data.
a) Collection of observation data on rainfall, temperature in the watershed, and the forecasting area over the past period;
b) Water level and flow rate changes at upstream stations within the watershed and the forecasting area over the past period;
c) Tide changes within the watershed and the forecasting area over the past period. Collection of observation data from tide gauge stations affecting the forecasting and warning areas;
d) Collection of information and data on reservoir operation and water conservancy works within the forecasting area and its vicinity;
đ) Collection of salinity measurement data from salinity monitoring stations within the watershed, the forecasting area, and its vicinity;
e) Information and planned anticipated water demand in the watershed and the forecasting area, as well as water demand for agriculture, aquaculture, and other economic and social activities (if any);
g) Rainfall forecast bulletin serving salinity intrusion forecasting.
2. Analysis and evaluation of the current situation
a) Weather trend analysis: Changes in rainfall volume and spatial distribution over time; rainfall forecast information within the watershed and the forecasting area during the forecast and warning period;
b) Hydrological trend analysis: Analysis of water level and flow rate trends within the watershed and the forecasting area; analysis of the impact of reservoir operation factors, hydropower projects, and water conservancy works within the watershed on the flow within the watershed and the forecasting area; analysis of salinity intrusion trends and highest salinity levels within the forecasting area over the past period; analysis of the influence of tidal regime on the scope of salinity intrusion impact; compilation of warning information on dangerous phenomena such as high tides and sea level rise affecting salinity intrusion trends in the forecasting area.
3. Implementation of forecasting and warning plans
a) Forecasting and warning methods used in the National Meteorological and Hydrological Forecasting and Warning System for salinity intrusion: Statistical method-based approach; mathematical model-based approach (regression models, substance transport models); other approaches based on different methods;
b) Based on specific conditions, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the use of forecasting and warning plans as appropriate.
4. Discussion on Forecasting and Warning
a) Evaluating the reliability of forecasting results using different methods in recent forecast bulletins;
b) Synthesize initial forecasting and warning results from different methods and the opinions of forecasters;
c) The person responsible for issuing the bulletin selects and issues the final forecast conclusion ensuring reliability within the forecast period.
5. Construction of Forecasting and Warning Bulletins
a) The National Meteorological and Hydrological Forecasting and Warning System shall establish and issue salinity intrusion forecast and warning bulletins in accordance with Clause 3 of Article 17 and Clauses 4 and 5 of Article 18 of Decision No. 18/2021/QĐ-TTg;
b) Based on actual requirements, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the content of the bulletin as appropriate.
6. Provision of Forecasting and Warning Bulletins
a) The National Meteorological and Hydrological Forecasting and Warning System shall provide salinity intrusion forecast and warning bulletins in accordance with Article 34 of Decision No. 18/2021/QĐ-TTg;
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the list of addresses to be provided with bulletins in accordance with actual requirements.
7. Supplemental Forecast and Warning Bulletins In case complex developments in salinity intrusion are detected, supplemental forecast and warning bulletins shall be issued outside those issued according to Article 27 of this Circular. The issuance of supplemental bulletins shall be carried out in accordance with Clauses 1, 2, 3, 4, 5, and 6 of this Article.
8. Evaluation of Forecasting and Warning Quality
a) The National Meteorological and Hydrological Forecasting and Warning System: Evaluation of full implementation of Clauses 1, 2, 3, 4, 5, 6, and 7 of this Article; evaluation of the completeness and timeliness of salinity intrusion forecasting and warning as stipulated in Clause 3 of Article 17, Clauses 4 and 5 of Article 18, and Clause 1 of Article 35 of Decision No. 18/2021/QĐ-TTg; evaluation of the quality of salinity intrusion forecast and warning bulletins as stipulated in Article 25 of Circular No. 42/2017/TT-BTNMT. The evaluation of the quality of salinity intrusion forecast and warning bulletins shall be conducted after sufficient observation data has been collected within the forecast period of the bulletin.
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system must comply with current regulations on evaluating forecasting quality.
Article 27. Frequency and Time for Issuing Salinity Intrusion Forecast and Warning Bulletins
1. The national meteorological and hydrological forecast and warning system shall issue salinity intrusion forecast and warning bulletins at frequencies and times as prescribed in Clause 3 of Article 19 of Decision No. 18/2021/QĐ-TTg.
2. Organizations and individuals not belonging to the national weather forecasting and warning system shall be responsible for specifying the frequency and time of issuing forecast and warning bulletins in accordance with actual requirements.
Section 9. TECHNICAL PROCEDURES FOR DOWNDRAFT, TORNADO, LIGHTNING, AND HAIL WARNING
Article 28. Content of Drought, Tornado, Lightning, and Hail Warnings
1. Possibility of occurrence of downpour, tornado, lightning, and hail phenomena.
2. Affected area and time of impact.
3. Risk level due to tornado, lightning, and hail.
Article 29. Technical Procedures for Drought, Tornado, Lightning, and Hail Warnings
1. Collecting and processing various types of information and data
a) Data on weather patterns capable of producing downpour, tornado, lightning, and hail on weather maps;
b) Surface meteorological observation data;
c) Forecast and warning data on downpour, tornado, lightning, and hail through numerical value products;
d) Satellite, radar, reconnaissance, and lightning location system observation data.
2. Analysis and evaluation of the current situation
a) Evaluating and analyzing collected data to identify weather patterns capable of producing downpour, tornado, lightning, and hail;
b) Analyzing and evaluating radio frequency feedback from weather radars, lowest cloud top temperatures from satellite meteorological data, lightning frequency and density from the lightning location system;
c) Determining the extent of downpour, tornado, lightning, and hail occurrences;
d) Determining the development of downpour, tornado, lightning, and hail within 24 to 48 hours prior.
3. Implement warning plans
a) Methods used in downpour, tornado, lightning, and hail warnings in the national meteorological and hydrological forecast and warning system: Statistical method-based approach; numerical model-based approach (individual and combined); analysis based on forecasters' experience using statistical forecast results and numerical model forecasts; other method-based approaches.
b) Based on specific conditions, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the use of forecasting and warning plans as appropriate.
4. Discuss warning The person responsible for issuing the bulletin shall quickly discuss with forecasters on duty before releasing the bulletin.
5. Develop warning bulletins
a) National meteorological and hydrological forecast and warning system: Establishing and issuing tornado, lightning, and hail warning bulletins as stipulated in Clause 1 of Article 23 and Clause 1 of Article 24 of Decision No. 18/2021/QĐ-TTg; establishing and issuing downpour forecast and warning bulletins including: Title of the downpour warning bulletin for a specific area, downpour warning and affected area, time of issuance of the bulletin, name and signature of the person responsible for issuing the bulletin;
b) Based on actual requirements, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the content of the bulletin as appropriate.
6. Provide warning bulletins
a) The national meteorological and hydrological forecast and warning system provides downpour, tornado, lightning, and hail warning bulletins as prescribed in Article 34 of Decision No. 18/2021/QĐ-TTg;
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the list of addresses to be provided with bulletins in accordance with actual requirements.
7. Supplementing Warning Bulletins In case of unusual developments in downpour, tornado, lightning, and hail conditions, additional downpour, tornado, lightning, and hail warning bulletins must be issued outside those issued according to the provisions of Article 30 of this Circular. The supplementation of bulletins shall be carried out in accordance with the provisions of Clauses 1, 2, 3, 4, 5, and 6 of this Article.
8. Evaluate the quality of warnings
a) The national meteorological and hydrological forecast and warning system: Evaluating the full implementation of Clause 1, Clause 2, Clause 3, Clause 4, Clause 5, Clause 6, and Clause 7 of this Article; assessing the completeness and timeliness of downpour, tornado, lightning, and hail warnings as prescribed in point a of Clause 5 of this Article and Clause 1 of Article 23, Clause 1 of Article 24, and Clause 1 of Article 35 of Decision No. 18/2021/QĐ-TTg; assessing the quality of downpour, tornado, lightning, and hail warning bulletins as prescribed in Article 22 of Circular No. 41/2017/TT-BTNMT. The assessment of the quality of downpour, tornado, lightning, and hail warning bulletins shall be conducted after sufficient observation data has been obtained within the warning period specified in the bulletin.
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system must comply with current regulations on evaluating forecasting quality.
Article 30. Frequency and Time for Issuing Thunderstorm, Tornado, Lightning, and Hail Warning Bulletins
1. National weather forecasting and warning system
a) Issue tornado, lightning, and hail warning bulletins at frequencies and times as prescribed in Article 25 of Decision No. 18/2021/QĐ-TTg.
b) Issue thunderstorm warning bulletins at least 30 minutes before the occurrence of the phenomenon. Continuous updates to the thunderstorm warning bulletins shall be made according to specific developments.
2. Organizations and individuals not belonging to the national weather forecasting and warning system shall be responsible for specifying the frequency and time of issuing forecast and warning bulletins in accordance with actual requirements.
Section 10. TECHNICAL PROCEDURES FOR FORECASTING AND WARNING STRONG WINDS ON THE SEA, LARGE WAVES, TIDAL FLOODS, SPRINGS, AND FOG
Article 31. Content of Forecasting and Warning Large Waves and Tidal Floods Caused by Tropical Depression and Typhoon
1. The highest wave height and affected area.
2. The highest tidal flood height, the highest total water level, and the affected area.
3. Warning areas along the coast that are at risk of flooding due to tidal floods combined with spring tides.
4. The level of natural disaster risk caused by large waves and tidal floods.
Article 32. Technical Procedures for Forecasting and Warning Large Waves and Tidal Floods Caused by Tropical Depression and Typhoon
1. Collection and processing of various types of information and data
a) Data from meteorological and oceanographic stations on wind speed, air pressure, waves, and water levels within the forecast area;
b) Data from buoys, marine radars, and ships on wind speed, air pressure, and waves within the forecast area (if available);
c) Forecast data on coordinates and air pressure at the center of tropical depression and typhoon;
d) Forecast data on wind speed, air pressure, waves, and tidal floods from numerical model forecasting products;
đ) Forecast data on waves and tidal floods issued by other forecasting centers domestically and internationally (if available);
e) Data and information on the current status of objects potentially affected by large waves and tidal floods and any damages (if any) caused by these phenomena.
2. Analysis and evaluation of the current situation
a) Determine the sea area with large waves (highest height, direction) and tidal floods (highest height, time of occurrence of the largest tidal flood);
b) Determine the development of waves (highest height, direction) and tidal floods (highest height) over the previous 6 to 12 hours;
c) Determine the tidal changes at coastal and island areas affected by tropical depression and typhoon over the previous 24 hours.
3. Implementation of forecasting and warning plans
a) Forecasting and warning procedures for large waves and tidal floods caused by tropical depression and typhoon in the national meteorological and hydrological forecasting and warning system: Procedures based on analysis of current conditions, experience, analytical formulas, and semi-analytical formulas; procedures based on results from numerical oceanographic models using wind fields and air pressure from numerical weather prediction models (individual and combined); procedures based on results from numerical oceanographic models using wind fields and air pressure calculated from tropical depression and typhoon forecast parameters (individual and combined); procedures based on other methods.
b) Based on specific conditions, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the use of forecasting and warning plans as appropriate.
4. Discussion on Forecasting and Warning
a) Evaluation of the reliability of forecast results from different methods and recent forecast bulletins;
b) Synthesizing forecasting results from various methods and the opinions of forecasters;
c) The person responsible for issuing the bulletin selects and issues the final forecast conclusion ensuring reliability within the forecast period.
5. Construction of Forecasting and Warning Bulletins
a) National meteorological and hydrological forecasting and warning system: Develop and issue large wave and tidal flood forecasting and warning bulletins caused by tropical depression and typhoon as stipulated in Clause 7 of Article 8, Clause 7 of Article 9, and Article 12 of Decision No. 18/2021/QĐ-TTg; such bulletins can be issued independently or included in tropical depression and typhoon forecasting and warning bulletins as stipulated in Clause 5 of Article 5 of this Circular.
b) Based on actual requirements, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the content of the bulletin as appropriate.
6. Provision of Forecasting and Warning Bulletins
a) The national meteorological and hydrological forecasting and warning system provides large wave and tidal flood forecasting and warning bulletins caused by tropical depression and typhoon as stipulated in Article 34 of Decision No. 18/2021/QĐ-TTg.
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the list of addresses to be provided with bulletins in accordance with actual requirements.
7. Supplemental Bulletins In cases where strong winds on the sea, large waves, and tidal floods caused by tropical depression and typhoon have particularly dangerous developments and potential for prolonged duration, supplemental forecasting and warning bulletins should be issued beyond those required under Article 33 of this Circular. The issuance of supplemental bulletins shall be carried out in accordance with Clauses 1, 2, 3, 4, 5, and 6 of this Article.
8. Evaluation of Forecasting and Warning Quality
a) The national meteorological and hydrological forecasting and warning system: Evaluate compliance with Clauses 1, 2, 3, 4, 5, 6, and 7 of this Article; assess the completeness and timeliness of large wave and tidal flood forecasting and warning caused by tropical depression and typhoon as stipulated in Clause 7 of Article 8, Clause 7 of Article 9, Article 12, and Clause 1 of Article 35 of Decision No. 18/2021/QĐ-TTg; evaluate the quality of large wave and tidal flood forecasting and warning caused by tropical depression and typhoon as stipulated in Articles 15 and 16 of Circular No. 16/2019/TT-BTNMT dated September 30, 2019, of the Minister of Natural Resources and Environment (hereinafter referred to as Circular No. 16/2019/TT-BTNMT). The evaluation of the quality of large wave and tidal flood forecasting and warning shall be conducted after sufficient observational data has been collected within the forecast period.
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system must comply with current regulations on evaluating forecasting quality.
Article 33. Frequency and time for issuing forecasts and warnings of large waves, storm surges caused by tropical depressions and typhoons
1. The national weather and hydrological forecast and warning system shall issue forecasts and warnings of large waves, storm surges caused by tropical depressions and typhoons at the same frequency and time as those for tropical depression and typhoon forecasts and warnings as stipulated in Clause 4, Article 13 of Decision No. 18/2021/QĐ-TTg.
2. Organizations and individuals not belonging to the national weather forecasting and warning system shall be responsible for specifying the frequency and time of issuing forecast and warning bulletins in accordance with actual requirements.
Article 34. Content of forecasts and warnings of strong winds over sea, large waves, storm surges caused by strong winds over sea
1. Strong wind (highest level, direction) and affected area.
2. Large wave (maximum height, direction) and affected area.
3. Storm surge (maximum height, time of occurrence), total water level (maximum height, time of occurrence) and affected area.
4. Warning of coastal areas at risk of flooding due to storm surges combined with tidal currents.
5. Level of disaster risk caused by strong winds over sea, large waves, storm surges caused by strong winds over sea.
Article 35. Technical forecasting and warning procedures for strong winds over sea, large waves, storm surges caused by strong winds over sea
1. Collection and processing of various types of information and data
a) Data from meteorological and oceanographic stations on wind speed, air pressure, waves, water levels in the forecast area;
b) Data from buoys, marine radars, and ships on wind speed, air pressure, and waves within the forecast area (if available);
c) Wind and air pressure data from weather maps;
d) Forecast data on wind speed, air pressure, waves, and tidal floods from numerical model forecasting products;
đ) Forecast data on waves and tidal floods issued by other forecasting centers domestically and internationally (if available);
e) Data and information on the current status of objects potentially affected by strong winds over sea, large waves, storm surges caused by strong winds and any damages (if any).
2. Analysis and evaluation of the current situation
a) Determine the sea area with strong wind (highest level, direction), large waves (height, direction), storm surge (height, time of maximum storm surge occurrence);
b) Determine the evolution of strong winds, large waves, and storm surges in the 6 to 12 hours prior period;
c) Determine the tidal evolution in coastal and island areas affected by strong winds, large waves, and storm surges in the 24-hour prior period.
3. Implementation of forecasting and warning plans
a) Forecasting and warning methods for strong winds over sea, large waves, storm surges caused by strong winds over sea in the national weather and hydrological forecast and warning system: Forecasting and warning method for strong winds over sea based on synoptic analysis and experience; forecasting method based on results from numerical weather prediction models; forecasting method based on other methods. Forecasting and warning method for large waves, storm surges caused by strong winds over sea based on current situation analysis, experience, analytical formulas, semi-experience formulas; forecasting method based on results from numerical hydrological models using wind fields and air pressure from numerical weather prediction models (individual and combined) and forecasting method based on other methods;
b) Based on specific conditions, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the use of forecasting and warning plans as appropriate.
4. Discussion on Forecasting and Warning
a) Evaluation of the reliability of forecast results from different methods and recent forecast bulletins;
b) Synthesizing forecasting results from various methods and the opinions of forecasters;
c) The person responsible for issuing the bulletin selects and provides the final forecast conclusion ensuring reliability within the forecast period.
5. Construction of Forecasting and Warning Bulletins
a) The national weather and hydrological forecast and warning system establishes and issues forecasts and warnings of strong winds over sea, large waves, storm surges caused by strong winds over sea according to the provisions of Clause 1, Clause 2 of Article 20 and Clause 2, Clause 3 of Article 21 of Decision No. 18/2021/QĐ-TTg;
b) Based on actual requirements, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the content of the bulletin as appropriate.
6. Provision of Forecasting and Warning Bulletins
a) The national weather and hydrological forecast and warning system provides forecasts and warnings of strong winds over sea, large waves, storm surges caused by strong winds over sea according to the provisions of Article 34 of Decision No. 18/2021/QĐ-TTg;
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the list of addresses to be provided with bulletins in accordance with actual requirements.
7. Supplementing forecasts and warnings In case of particularly dangerous and prolonged strong winds over sea, large waves, storm surges caused by strong winds over sea, additional forecasts and warnings shall be issued beyond those issued according to the provisions of Article 36 of this Circular. The supplementation of forecasts and warnings shall be carried out according to the provisions of Clauses 1, 2, 3, 4, 5, and 6 of this Article.
8. Evaluation of Forecasting and Warning Quality
a) National weather and hydrological forecast and warning system: Evaluate the full implementation of Clauses 1, 2, 3, 4, 5, 6, and 7 of this Article; evaluate the completeness and timeliness of forecasts and warnings of strong winds over sea, large waves, storm surges caused by strong winds over sea as stipulated in Clauses 1, 2 of Article 20, Clauses 2, 3 of Article 21, and Clause 1 of Article 35 of Decision No. 18/2021/QĐ-TTg; evaluate the quality of forecasts and warnings of strong winds over sea, large waves, storm surges caused by strong winds over sea as stipulated in Clause 6 of Circular No. 41/2017/TT-BTNMT and Articles 15, 16 of Circular No. 16/2019/TT-BTNMT. The evaluation of the quality of forecasts and warnings of strong winds over sea, large waves, storm surges caused by strong winds over sea shall be conducted after sufficient observation data has been collected within the forecast bulletin period.
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system must comply with current regulations on evaluating forecasting quality.
Article 36. Frequency and Time for Issuing Marine Strong Wind Forecast and Warning Bulletins, Large Waves, and Water Rise Caused by Marine Strong Winds
Clause 1. The National Meteorological and Hydrological Forecasting and Warning System shall issue marine strong wind forecast and warning bulletins, large wave warnings, and water rise caused by marine strong winds with frequency and time as prescribed in Clause 2, Article 22 of Decision No. 18/2021/QĐ-TTg.
2. Organizations and individuals not belonging to the national weather forecasting and warning system shall be responsible for specifying the frequency and time of issuing forecast and warning bulletins in accordance with actual requirements.
Article 37. Content of Tide Surge Forecast and Warning
Point 1. Areas where tide surges occur.
Point 2. Height and time of occurrence of high water levels.
Point 3. Warning of areas at risk of flooding due to tide surges.
Article 38. Technical Forecasting and Warning Procedures for Tide Surges
1. Collection and processing of various types of information and data
a) Data from water level observations at tide gauge stations within the forecasting area;
b) Predictive tidal data from numerical model products;
c) Predictive tidal data transmitted from other forecasting centers both domestically and internationally (if available);
d) Data and information on objects potentially affected by tide surges and damages (if any).
2. Analysis and evaluation of the current situation
a) Determination of coastal and island areas where tide surges occur: Size and time of occurrence of high water levels and low water levels;
b) Determination of wind intensity and direction, wave height and direction, and water rise height in the area where tide surges occur within 6 to 12 hours prior;
Clause 3. Implementation of Forecasting and Warning Plans
a) Forecasting and warning plans used in the National Meteorological and Hydrological Forecasting and Warning System for tide surges: Harmonic analysis-based plan; numerical model-based plan; forecasting plan based on other methods;
b) Based on specific conditions, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the use of forecasting and warning plans as appropriate.
4. Discussion on Forecasting and Warning
a) Evaluation of the reliability of forecast results from different methods and recent forecast bulletins;
b) Compilation of original forecasting results from different plans and forecasters' assessments;
c) The person responsible for issuing the bulletin selects and provides the final forecast conclusion ensuring reliability within the forecast period.
5. Construction of Forecasting and Warning Bulletins
a) The National Meteorological and Hydrological Forecasting and Warning System shall develop and issue tide surge forecast and warning bulletins when detecting potential tide surges occurring within 72 hours ahead, including: Title of the tide surge forecast and warning bulletin for specific areas; information on current tidal conditions in areas where tide surges occur, tide surge development, height and time of occurrence of high water levels; information on wind (intensity, direction), waves (height, direction), maximum water rise height; assessment of flood risks due to tide surges; issuance time of the bulletin; name and signature of the responsible issuer;
b) Based on actual requirements, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the content of the bulletin as appropriate.
6. Provision of Forecasting and Warning Bulletins
a) The National Meteorological and Hydrological Forecasting and Warning System shall provide tide surge forecast and warning bulletins to relevant ministries, sectors, localities, organizations involved in disaster prevention, response, and aftermath mitigation; and agencies and organizations disseminating disaster information.
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the list of addresses to be provided with bulletins in accordance with actual requirements.
Clause 7. Supplementing Forecast and Warning Bulletins In case of abnormal tide surge developments, supplementary forecast and warning bulletins shall be issued outside those issued according to Article 39 of this Circular. Such supplements shall be carried out in accordance with Clauses 1, 2, 3, 4, 5, and 6 of this Article.
8. Evaluation of Forecasting and Warning Quality
a) The National Meteorological and Hydrological Forecasting and Warning System: Evaluation of full implementation of Clauses 1, 2, 3, 4, 5, 6, and 7 of this Article; evaluation of the completeness and timeliness of tide surge forecasts and warnings as stipulated in point a, Clause 5 of this Article, with the latest completion time being 15 minutes from the end of the most recent forecast and warning bulletin; evaluation of the quality of tide surge forecasts and warnings as prescribed in Article 17 of Circular No. 16/2019/TT-BTNMT. Quality evaluations of tide surge forecasts and warnings shall be conducted after sufficient observation data has been collected within the forecast bulletin's timeframe.
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system must comply with current regulations on evaluating forecasting quality.
Article 39. Frequency and time of issuing tide forecast and warning bulletins
1. The national weather forecasting and warning system shall issue the first tide forecast and warning bulletin when the possibility of high tide occurrence is detected in the warning area; subsequent bulletins shall be issued daily at 15:30 until the end of the high tide period.
2. Organizations and individuals not belonging to the national weather forecasting and warning system shall be responsible for specifying the frequency and time of issuing forecast and warning bulletins in accordance with actual requirements.
Article 40. Content of fog forecast and warning
1. Time of fog occurrence.
2. Affected areas.
3. Level of natural disaster risk due to fog.
Article 41. Technical process for fog warning
1. Collection and processing of various types of information and data
a) Weather data, including surface observations, radio sounding, fog observation data, temperature, dew point temperature at meteorological stations in the forecast area;
b) Satellite weather data from satellite observations and secondary products.
c) Weather radar data;
d) Numerical model data.
2. Analysis and evaluation of the current situation
a) Analyze and evaluate the current status of collected data to identify the activities of weather patterns and related characteristics causing fog; determine areas where fog reduces visibility, and the time of occurrence.
b) Determine the past development of fog and assess the current status of fog regarding time, area, intensity of fog, and the extent of its impact over the last 6 to 12 hours.
3. Implement warning plans
a) Warning plans used in the national weather forecasting and warning system: Plans based on synoptic analysis methods and expert analysis; plans based on statistical methods using current and past observational information and future forecasts; short-term (3-6 hour) warning plans based on automatic rainfall estimates from satellites and radar; plans based on numerical modeling methods (single and ensemble forecasts); plans based on other methods.
b) Based on specific conditions, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the use of forecasting and warning plans as appropriate.
4. Discuss warnings
a) Evaluate the reliability of warning results using different methods and the most recent forecast bulletins.
b) Synthesize warning results from various methods and the assessments of forecasters.
c) The person responsible for issuing the bulletin selects and presents the final warning conclusion ensuring reliability within the warning timeframe.
5. Develop warning bulletins
a) The national weather forecasting and warning system establishes and issues fog warning bulletins in accordance with Clause 3, Article 20 and Clause 4, Article 21 of Decision No. 18/2021/QĐ-TTg.
b) Based on actual requirements, organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the content of the bulletin as appropriate.
6. Provide warning bulletins
a) The national weather forecasting and warning system provides fog warning bulletins in accordance with Article 34 of Decision No. 18/2021/QĐ-TTg.
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the list of addresses to be provided with bulletins in accordance with actual requirements.
7. Supplementing warning bulletins In case of prolonged and complex fog developments, additional warning bulletins shall be issued outside those stipulated in Article 42 of this Circular. The supplementation of bulletins shall be carried out according to the provisions of Clauses 1, 2, 3, 4, 5, and 6 of this Article.
8. Evaluate the quality of warnings
a) The national weather forecasting and warning system: Evaluates the full implementation of Clauses 1, 2, 3, 4, 5, 6, and 7 of this Article; evaluates the completeness and timeliness of fog warnings as prescribed in Clause 3, Article 20, Clause 4, Article 21, and Clause 1, Article 35 of Decision No. 18/2021/QĐ-TTg; evaluates the quality of fog warnings conducted in accordance with Clause 5, Article 12 of Circular No. 41/2017/TT-BTNMT. The evaluation of fog warning quality shall be conducted after sufficient observation data has been collected within the warning bulletin timeframe.
b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system must comply with current regulations on evaluating forecasting quality.
Article 42. Frequency and Time for Issuing Fog Warning Bulletins
1. The national meteorological and hydrological forecasting and warning system shall issue fog warning bulletins at frequencies and times as prescribed in Clause 3 of Article 22 of Decision No. 18/2021/QĐ-TTg.
2. Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system shall independently determine the frequency and time for issuing bulletins in accordance with actual needs.
Chapter III
IMPLEMENTING PROVISIONS
Article 43. Effective Date
1. This Circular takes effect from March 15, 2023.
2. This Circular replaces Circular No. 41/2016/TT-BTNMT dated December 21, 2016 of the Minister of Natural Resources and Environment on Technical Procedures for Forecasting and Warning Hazardous Meteorological and Hydrological Phenomena.
3. In cases where the legal normative documents cited in this Circular are amended or supplemented, they shall be implemented according to the provisions of the amended or supplemented documents.
Article 44. Responsibility for Implementation
1. The Minister, Heads of Ministries equivalent to Ministries, Heads of Government Agencies, Chairpersons of People's Committees of provinces and centrally governed cities, Heads of units under the Ministry of Natural Resources and Environment, and related agencies, organizations, and individuals are responsible for implementing this Circular.
2. The Director of the National Centre for Hydro-meteorological Forecasting is responsible for assisting the Minister of Natural Resources and Environment in urging and inspecting the implementation of this Circular./.
DEPUTY MINISTER
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