Circular No. 41/2016/TT-BTNMT on the technical forecasting and warning procedures for dangerous meteorological and hydrological phenomena

✦ 스마트 요약

This Circular stipulates the technical forecasting and warning procedures for extreme meteorological and hydrological phenomena such as droughts, saline intrusion, thunderstorms, lightning, typhoons, tornadoes, hail, and localized heavy rainfall. It includes contents such as information collection, data processing, implementation of forecasting plans, discussion of forecasting results, construction of forecast bulletins, and provision of bulletins to relevant agencies.

적용 범위

This applies to organizations and individuals operating in the field of meteorology and hydrology in Vietnam.

핵심 사항

Specifies the content of forecasts and warnings for droughts, saline intrusion, thunderstorms, lightning, typhoons, tornadoes, hail, and localized heavy rainfall.
Requires information collection from sources such as meteorological satellites, weather radars, lightning location data.
Forecasting plans include the use of correlation maps, statistics, and mathematical models.
Discusses forecasting results to select the most reliable outcomes.
Constructs and provides forecast bulletins according to specified frequency and timeframes.

🌐 이 문서의 사회적 영향

Aids competent authorities in making timely decisions to respond to extreme meteorological and hydrological phenomena.
Provides accurate forecast information to the public, helping them to proactively avoid dangers.

❓ 자주 묻는 질문

Does this Circular specify the frequency and timing for issuing forecast bulletins?

Yes, this Circular specifically stipulates the frequency and timing for issuing forecast bulletins for each type of meteorological and hydrological phenomenon.

Which forecasting methods are used in this Circular?

This Circular refers to traditional forecasting methods such as correlation maps, statistics, and the use of mathematical models.

전문

MINISTRY OF NATURAL RESOURCES AND ENVIRONMENT ENVIRONMENT -------	SOCIALIST REPUBLIC OF VIET NAM Independence - Freedom - Happiness ---------------
Number: 41/2016/TT-BTNMT	Hanoi, December 21, 2016

CIRCULAR

REGULATIONS ON TECHNICAL PROCEDURES FOR PREDICTING AND WARNING DANGEROUS METEOROLOGICAL HYDROLOGICAL PHENOMENA

Pursuant to the Law on Meteorology and Hydrology dated November 23, 2015;

Pursuant to the Law on Natural Disaster Prevention and Control dated June 19, 2013;

On the basis of Government Decree No. Decree No. 38/2016/NĐ-CP dated May 15, 2016 of the Government detailing certain provisions of the Law on Meteorology and Hydrology;

On the basis of Government Decree No. Decree No. 21/2013/NĐ-CP dated March 4, 2013 of the Government stipulating functions, tasks, powers, and organizational structure; organization of the Ministry of Natural Resources and Environment;

On the basis of Decision No. Decision No. 46/2014/QĐ-TTg dated August 15, 2014 of the Prime Minister Government On forecasting, warning, and disseminating information about natural disasters;

Pursuant to Decision No. 44/2014/QĐ-TTg dated August 15, 2014 of the Prime Minister stipulating CV3: 16º56'21" N, 107º11'06" E; levels of natural disaster risk;

At the proposal of the Director of the National Center for Hydro-Meteorological Forecasting, the Director of the General Department of Meteorology, Hydrology, and Climate Change, and the Head of the Legal Department;

The Minister of Natural Resources and Environment promulgates this Circular stipulating for Technical procedures for predicting and warning dangerous meteorological and hydrological phenomena.

PART I

GENERAL PROVISIONS

Article 1. Scope of Regulation

This Circular stipulates technical procedures for predicting and warning dangerous meteorological and hydrological phenomena, including: Tropical depression, typhoon; widespread heavy rain; flood, inundation; flash flood, landslides, subsidence caused by floods or runoff; cold air; heat wave; drought; saltwater intrusion; thunderstorm, lightning, hail, tornado, localized heavy rain; sea fog, large waves, water level rise in tropical depression, typhoon, monsoon, and spring tide.

Article 2. Applicability

This Circular applies to the national meteorological and hydrological forecasting and warning system; organizations and individuals engaged in forecasting and warning activities licensed by the Ministry of Natural Resources and Environment or of the National Assembly; provincial people's committees to conduct meteorological and hydrological forecasting and warning activities.

Article 3. Explanation of Terms

In this Circular, the following terms are understood as follows:

1. Forecast plan is a specific method for analyzing, calculating, predicting, and warning about meteorological and hydrological factors or phenomena at a location or area.

2. Forecast quality assessment involves activities aimed at determining the completeness and timeliness of forecast bulletins and the reliability of forecasted factors and phenomena.

3. Supplementing forecast bulletins are refers to increasing the number of forecast bulletins beyond the prescribed requirements to adjust and refine the content based on the latest information, ensuring timely response and reliability of forecasts. Supplementing forecast bulletins is an essential part of forecasting and warning activities.

4. Forecast discussion is an activity involving the exchange of information, analysis, and evaluation of forecast results by forecasters, experts, and different forecast plans to select the final forecast result with the highest reliability.

5. Forecast error is the difference between the forecast and the actual measurement of meteorological and hydrological phenomena at the time , Đ of the forecast, including errors in value, time, space, and the likelihood of occurrence of phenomena.

6. Large waves are waves on the sea with a height greater than or equal to 2 meters.

7. Cold air is a dangerous weather phenomenon caused by cold air masses from the north invading our country, changing the existing wind system in the north into a wind system with a northerly component and increased pressure.

8. Severe cold is a special type of winter weather occurring in northern Vietnam when the average daily air temperature drops below 15 degrees Celsius.

9. Thunderstorm is a sudden electrical discharge manifested as a flash (lightning) and a sharp or rumbling sound (thunder). Thunderstorms often occur with convective clouds (cumulonimbus clouds) and are accompanied by precipitation in the form of showers, hail, or sometimes snow, ice pellets, or graupel.

10. Fog is a phenomenon where water vapor condenses into tiny droplets in the air layer near the surface, reducing horizontal visibility to less than 1 kilometer.

11. Frost is a phenomenon where water vapor rises and condenses into tiny ice particles upon encountering cold air at the surface.

12. Localized heavy rain is a phenomenon where rainfall occurs within a small area with a total amount exceeding 30 millimeters in one hour.

Chapter II

TECHNICAL PROCEDURES FOR PREDICTING AND WARNING TROPICAL DEPRESSIONS AND TYPHOONS

Article 4. Content of tropical low pressure system forecast and typhoon warning

1. Position of the typhoon center, tropical low pressure system within the forecast period.

2. Strongest wind level near the center of the tropical low pressure system, typhoon; strongest gust level.

3. Range of strong winds at levels 6 and 10.

4. Large waves, water surge, flooding in coastal areas.

5. Strong winds on land.

6. Widespread heavy rain.

Article 5. Technical Forecasting Process

Based on observational data and information indicating the possibility of appearance or already existing signs of tropical low pressure systems and typhoons, the following contents shall be carried out:

1. Collecting and processing various types of data

a) Data on tropical low pressure systems and typhoons on weather maps;

b) Enhanced observation data when tropical low pressure systems and typhoons have the potential to affect the mainland;

c) Data on tropical low pressure systems and typhoons through remote sensing information;

d) Data on tropical low pressure systems and typhoons from numerical forecast products;

đ) Data on tropical low pressure systems and typhoons from international typhoon forecasting centers.

2. Analyzing and evaluating current status

a) Determine the position of the tropical low pressure system and typhoon center based on satellite data analysis, weather radar data, observational data, and other relevant information;

b) Determine the maximum wind speed and gusts in the vicinity of the tropical low pressure system and typhoon center based on satellite data analysis, weather radar data, observational data, and other relevant information;

c) Determine the radius of strong winds at levels 6 and 10 based on satellite data analysis, weather radar data, observational data, and other relevant information;

d) Determine the movement direction and speed, and the maximum wind speed near the tropical low pressure system and typhoon center within 6 to 12 hours before based on satellite data analysis, weather radar data, observational data, and other relevant information.

3. Implement forecasting and warning plans for tropical low pressure systems and typhoons

a) The plans commonly used in forecasting and warning tropical low pressure systems and typhoons include:

a1) Plans for forecasting and warning the position of the center, the strongest wind level, and the strongest gust level within the forecast period:

- Plan based on synoptic analysis method and experience;

- Plan based on remote sensing information analysis and forecast results;

- Plan based on the synthesis of results from international typhoon forecasting centers;

- Plan based on global, regional numerical models, coupled atmosphere-ocean models;

- Plan based on combined methods;

- Plan based on other methods (if available).

a2) Plans for forecasting and warning the range of strong winds at levels 6 and 10:

- Plan based on the correlation between observed wind speed and distance to the typhoon center;

- Plan based on remote sensing information analysis;

- Plan based on the synthesis of results from international typhoon forecasting centers.

a3) Plans for forecasting and warning strong winds on land:

- Plan based on synoptic analysis method and experience;

- Plan based on the correlation between observed wind speed and distance to the typhoon center;

- Plan based on global, regional numerical models, coupled atmosphere-ocean models;

- Plan based on combined methods;

- Plan based on other methods (if available).

a4) Plans for forecasting and warning large waves, water surge in tropical low pressure systems and typhoons, coastal flooding are specified in point a2, point a3 Clause 3 Article 32 of this Circular.

a5) Plans for forecasting and warning widespread heavy rain are specified in Clause 3 Article 8 of this Circular.

b) Forecasting and warning plans for tropical low pressure systems and typhoons used in the national meteorological and hydrological forecasting and warning system are regulated by the National Meteorological and Hydrological Center.

c) Depending on specific conditions, organizations and individuals engaged in forecasting and warning outside the national meteorological and hydrological forecasting and warning system shall independently determine the use of forecasting and warning plans appropriately.

4. Discussing tropical low pressure system and typhoon forecasts and warnings

a) Analyze and evaluate the reliability of forecast results using different methods in the most recent forecast bulletins.

b) Synthesize initial forecast results from different methods and the opinions of forecasters.

c) The person responsible for issuing the bulletin selects the final forecast result with the highest reliability suitable for the forecast period. in the Field of Teachers and Educational Institution Managers time limit for the forecast.

5. Building the forecast and warning bulletin for tropical low pressure systems and typhoons

a) Issuing the forecast and warning bulletin for tropical low pressure systems and typhoons is carried out according to the provisions of Articles 8 and 9 of Decision No. 46/2014/QĐ-TTg dated August 15, 2014 of the Government Chairman regulating forecasting, warning, and transmitting disaster information.

b) The content of the forecast and warning bulletin for tropical low pressure systems and typhoons is carried out according to the provisions of Articles 10 and 11 of Decision No. 46/2014/QĐ-TTg dated August 15, 2014 of the Government Chairman regulating forecasting, warning, and transmitting disaster information.

c) Information about heavy rain, large waves, water surge in tropical low pressure systems and typhoons, coastal flooding is integrated into the forecast and warning bulletin for tropical low pressure systems and typhoons.

d) Warning the risk level of disasters caused by tropical low pressure systems and typhoons, heavy rain, water surge in typhoons is carried out according to the provisions of Articles 3, 5, and 14 of Decision No. 44/2014/QĐ-TTg dated August 15, 2014 of the Government Chairman detailing the risk level of disasters.

6. Providing the forecast and warning bulletin for tropical low pressure systems and typhoons

a) National meteorological and hydrological forecasting and warning system

Forecast and warning bulletins for tropical low pressure systems and typhoons are provided according to the provisions of Articles 24 and 25 of Decision No. 46/2014/QĐ-TTg dated August 15, 2014 of the Government Chairman regulating forecasting, warning, and transmitting disaster information.

b) Organizations and individuals not belonging to the national meteorological and hydrological forecasting and warning system independently determine the list of addresses to provide bulletins in accordance with actual needs.

7. Supplementing the forecast and warning bulletin for tropical low pressure systems and typhoons

In case of detecting abnormal development of tropical low pressure systems and typhoons, additional forecast and warning bulletins for tropical low pressure systems and typhoons shall be issued outside the regular bulletins issued according to Article 6 of this Circular. The supplementation of bulletins is carried out according to the provisions from Clause 1 to Clause 6 of this Article.

8. Evaluating the quality of tropical low pressure system and typhoon forecasts and warnings

a) Evaluation content

a1) Evaluate the full and timely implementation of the contents prescribed in the technical forecasting and warning process for tropical low pressure systems and typhoons;

a2) Evaluate the completeness and timeliness of providing forecast and warning bulletins for tropical low pressure systems and typhoons as prescribed;

a3) Evaluate the quality of the tropical depression and typhoon forecast and warning bulletins through comparing predictive factors with actual observations. The evaluation factors include: center position, strongest wind speed, time of direct impact onset, landfall time, scope of direct impact, strong winds, and rainfall on land.

b) The National Hydro-Meteorological Center shall specify in detail the methods and criteria for evaluating tropical depression and typhoon forecast and warning bulletins within the national hydro-meteorological forecasting and warning system.

c) Organizations and individuals not part of the national hydro-meteorological forecasting and warning system must comply with current regulations regarding forecast quality assessment.

Article 6. Frequency and Time of Issuing Tropical Depression and Typhoon Bulletins

Tropical depression and typhoon forecast and warning bulletins shall be issued at frequencies and times as prescribed in Article 12 of Decision No. 46/2014/QD-TTg dated August 15, 2014, of the Government Chairman on Forecasting, Warning, and Transmitting Natural Disaster Information.

Chapter III

TECHNICAL PROCEDURE FOR LARGE-SCALE RAINFALL FORECASTING AND WARNING

Article 7. Content of Large-Scale Rainfall Forecasting and Warning

1. Rainfall amount.

2. Duration of rain.

3. Rainfall area.

4. Rain intensity.

Article 8. Technical Procedure

Based on observation data indicating the potential or occurrence of large-scale rainfall, the following actions should be taken:

1. Collecting and processing various types of information and data

a) Short-term and medium-term weather forecast and warning bulletins.

b) Meteorological satellite data from infrared and visible light channels, and secondary products (convective cloud analysis, cloud classification, rainfall estimation, etc.).

c) Weather radar data and composite radar images, rainfall estimates within the forecast and warning areas.

d) Surface observation data (including automatic observations) and radio frequency remote sensing data in the forecast and warning areas and adjacent regions.

đ) Analysis and forecast data from global models, high-resolution regional models, and hybrid models.

e) Collecting forecast and large-scale rainfall information from meteorological forecasting centers in the region and internationally.

g) Evaluating the completeness and accuracy of collected data and supplementing, correcting, and standardizing the data.

2. Analyzing and evaluating current status

a) Synoptic map analysis at standard pressure levels combined with model output and remote sensing data to determine synoptic patterns causing large-scale rainfall.

b) Assessing past large-scale rainfall trends and current status regarding duration, area, intensity, and total rainfall.

3. Implementing large-scale rainfall forecasting and warning plans

a) Commonly used plans in large-scale rainfall forecasting and warning include:

a1) Plans based on atmospheric circulation analysis.

a2) Plans based on numerical models.

a3) Plans based on satellite cloud imagery and radar images.

b) Large-scale rainfall forecasting and warning plans used in the national hydro-meteorological forecasting and warning system are specified by the National Hydro-Meteorological Center.

4. Discussing Large-Scale Rainfall Forecasting and Warning

a) Analyzing and assessing the reliability of forecasting results using different methods in the latest forecast and warning bulletins.

b) Compiling forecasting and warning results from various methods and forecasters' opinions.

c) The person responsible for issuing the bulletin selects the most reliable final forecast result.

5. Preparing Large-Scale Rainfall Forecasting and Warning Bulletins

a) For the national hydro-meteorological forecasting and warning system

a1) Title of the large-scale rainfall bulletin according to the expected time and affected area.

a2) Past rainfall trends, total rainfall, rainfall area, duration, and intensity in the forecast area.

a3) Forecast and assessment of future rainfall trends, total rainfall, rainfall area, duration, and intensity in the forecast area.

a4) Natural disaster risk level warnings due to large-scale rainfall are implemented according to Article 5 of Decision No. 44/2014/QD-TTg dated August 15, 2014, of the Government Chairman detailing natural disaster risk levels.

a5) In cases where rainfall may cause floods, flash floods, and landslides, additional flood, flash flood, and landslide warning information is provided.

a6) Bulletin issuance time and time for the next bulletin.

b) Depending on practical needs, organizations and individuals outside the national hydro-meteorological forecasting and warning system may independently define bulletin contents appropriately.

6. Providing Large-Scale Rainfall Forecasting and Warning Bulletins

a) National meteorological and hydrological forecasting and warning system

Large-scale rainfall forecasting and warning bulletins are provided according to Articles 24 and 25 of Decision No. 46/2014/QD-TTg dated August 15, 2014, of the Government Chairman on Forecasting, Warning, and Transmitting Natural Disaster Information.

7. Supplementing Large-Scale Rainfall Forecasting and Warning Bulletins

If unusual large-scale rainfall developments are detected, supplementary bulletins should be issued beyond those regularly scheduled under Article 9 of this Circular. Supplementary bulletins shall follow the procedures outlined in paragraphs 1 to 6 of this Article.

8. Evaluating the Quality of Large-Scale Rainfall Forecasting and Warning Bulletins

a) Evaluation content

a1) Assessing the timely and comprehensive implementation of the technical procedure for large-scale rainfall forecasting and warning.

a2) Assessing the timeliness and completeness of large-scale rainfall forecasting and warning bulletins provided according to regulations.

a3) Evaluating bulletin quality through comparing predictive factors with actual observations using specified evaluation methods.

b) The National Hydro-Meteorological Center shall specify in detail the methods and criteria for evaluating large-scale rainfall forecasting and warning bulletins within the national hydro-meteorological forecasting and warning system.

c) Organizations and individuals not part of the national hydro-meteorological forecasting and warning system must comply with current regulations regarding forecast quality assessment.

Article 9. Frequency and Time of Issuing Flood Forecast and Warning Bulletins

1. National Hydro-meteorological Forecasting and Warning System

a) Flood Forecast and Warning Bulletins for a 24-hour period: Four bulletins are issued daily at 4:30, 9:30, 15:30, and 21:30; in cases of particularly heavy or extremely dangerous rainfall, additional bulletins may be issued between the main bulletins.

b) Flood Forecast and Warning Bulletins for a 24 to 72-hour period: Two bulletins are issued daily at 4:30 and 15:30;

c) Flood Forecast and Warning Bulletins for a period exceeding 72 hours: One bulletin is issued daily at 15:30;

2. Organizations and individuals not belonging to the national hydro-meteorological forecasting and warning system shall independently determine the frequency and time of issuing flood forecast and warning bulletins according to actual conditions.

Chapter IV

TECHNICAL PROCEDURE FOR FLOOD FORECASTING AND WARNING

Article 10. Content of Flood Forecast and Warning

1. Water level or flow rate values at positions on river basins as specified in Appendix II and Appendix III of Decision No. 46/2014/QĐ-TTg dated August 15, 2014 of the Prime Minister regarding flood forecasting, warning, and disaster information dissemination corresponding to the expected time.

2. Flood trend.

3. Flood amplitude.

4. Time of peak flood occurrence.

5. Flood inundation area, depth of flooding, duration of flooding.

6. Water level height at flood reporting markers (if any).

Article 11. Technical Procedure

Based on observational data and information, identifying signs of flood, inundation, waterlogging, or when it is determined that the water level in rivers has the potential to reach the "flood" level as defined in Clause 26 and Clause 27, Article 4 of Decision No. 46/2014/QĐ-TTg dated August 15, 2014 of the Prime Minister regarding flood forecasting, warning, and disaster information dissemination, the following actions shall be carried out:

1. Collecting and processing various types of information and data

a) Collect additional rainfall, water level, and flow rate data from meteorological and hydrological stations, dedicated stations, discharge data from hydropower reservoirs, irrigation reservoirs, and related international reservoirs (if applicable);

b) Continuously update observational data;

c) Process and verify missing or delayed data, analyze and adjust data to ensure its accuracy.

2. Analyzing and evaluating current status

a) Analyze weather patterns causing rain: Analyze weather patterns causing rain, calculate average basin rainfall, determine rainfall intensity, rainfall area, rainfall center, start and end times of rainfall, and preliminarily assess rainfall extent, quantify rainfall, and predict subsequent rainfall times;

b) Analyze flood progression: Analyze water levels and flows at positions on river basins; calculate average and maximum flood rates during different periods; determine flood amplitude, flood transmission time along each river section; analyze reservoir operation conditions on river basins; preliminarily assess the severity of subsequent floods;

c) Analyze causes of inundation: Inundation due to dike breaches, flood releases, dam breaches, upstream reservoirs; lowland inundation due to heavy rainfall; tidal flood inundation; river flood inundation; other causes of inundation; identify areas already affected by inundation; preliminarily assess the likelihood of subsequent inundation and depth of inundation in those areas.

3. Implement flood forecasting and warning plans

a) Commonly used plans in flood forecasting and warning include:

a1) Plans based on rainfall-runoff relationship methods;

a2) Plans based on water level and flow rate station-to-station relationships along the same riverbank or within the same basin;

a3) Plans based on mathematical models: Regression models; lumped hydrological models; distributed parameter hydrological models; hydraulic models; reservoir regulation models.

b) Flood forecasting and warning plans used in the national hydro-meteorological forecasting and warning system are stipulated by the National Hydro-meteorological Center.

c) Depending on specific conditions, organizations and individuals engaged in forecasting and warning outside the national hydro-meteorological forecasting and warning system shall independently define the use of flood forecasting and warning plans accordingly.

4. Discuss flood forecasting and warning

a) Analyze and evaluate the reliability of forecast results using different methods in the most recent forecast bulletins.

b) Synthesize initial forecast results from different methods and the opinions of forecasters.

c) The person responsible for approving the bulletin selects the final forecast result with the highest reliability suitable for the type of bulletin and forecast period.

5. Develop flood forecasting and warning bulletins

a) Issuance of flood forecasting and warning bulletins is carried out in accordance with Article 13 and Article 22 of Decision No. 46/2014/QĐ-TTg dated August 15, 2014 of the Prime Minister regarding flood forecasting, warning, and disaster information dissemination.

b) The content of flood forecasting and warning bulletins is carried out in accordance with Article 14 and Article 23 of Decision No. 46/2014/QĐ-TTg dated August 15, 2014 of the Prime Minister regarding flood forecasting, warning, and disaster information dissemination.

c) Disaster risk level warnings due to floods and inundations are carried out in accordance with Article 10 of Decision No. 44/2014/QĐ-TTg dated August 15, 2014 of the Prime Minister detailing disaster risk levels.

6. Provide flood forecasting and warning bulletins

a) National meteorological and hydrological forecasting and warning system

Flood forecasting and warning bulletins are provided in accordance with Article 24 and Article 25 of Decision No. 46/2014/QĐ-TTg dated August 15, 2014 of the Prime Minister regarding flood forecasting, warning, and disaster information dissemination.

7. Supplement flood forecasting and warning bulletins

In cases where abnormal flood or inundation developments are detected, supplementary flood forecasting and warning bulletins shall be issued beyond those issued according to the provisions of Article 12 of this Circular. The issuance of supplementary bulletins shall be carried out in accordance with the provisions from Clause 1 to Clause 6 of this Article.

8. Evaluate the quality of flood forecasting and warning bulletins

a) Evaluation content

a1) Evaluate the full and timely implementation of the technical procedures for flood forecasting and warning;

a2) Evaluate the completeness and timeliness of the provision of flood forecasting and warning bulletins as prescribed;

a3) Evaluate the quality of the flood warning bulletin through the comparison of forecast and warning factors with actual observations according to prescribed evaluation methods.

b) The National Hydro-Meteorological Center shall provide detailed regulations on the methods and evaluation criteria for flood and inundation warning bulletins within the national hydro-meteorological forecasting and warning system.

c) Organizations and individuals not part of the national hydro-meteorological forecasting and warning system must comply with current regulations regarding forecast quality assessment.

Article 12. Frequency and Time of Issuing Flood and Inundation Warning Bulletins

Flood and inundation warning bulletins are issued at frequencies and times as stipulated in Articles 15 and 16 of Decision No. 46/2014/QĐ-TTg dated August 15, 2014, of the Government Chairman regarding flood and inundation forecasting, warning, and disaster information dissemination.

Chapter V

TECHNICAL PROCEDURE FOR WARNING FLASH FLOODS, LANDSLIDES, AND GROUND SUBSIDENCE CAUSED BY RAINFALL OR WATER FLOW

Article 13. Content of Flash Flood, Landslide, and Ground Subsidence Warnings Caused by Rainfall or Water Flow

Areas where they occur, time periods during which they occur, and the likelihood of occurrence of flash floods, landslides, and ground subsidence caused by rainfall or water flow.

Article 14. Technical Procedure

Based on observed data indicating the potential appearance or actual appearance of signs of flash floods, landslides, and ground subsidence caused by rainfall or water flow, the following contents should be implemented:

1. Collecting and processing various types of data

a) Data on topography, slope, past flash floods, landslides, areas at risk of flash floods and landslides in the warning area, which may be presented in text, tables, or maps;

b) Rainfall and water level observation data from stations in the warning area and nearby;

c) Estimated rainfall data using remote sensing information in the warning area and nearby;

d) Operation data of reservoirs in the warning area and nearby;

đ) Simulated and forecast rainfall data from numerical models;

e) Flash flood, landslide, and ground subsidence warnings caused by rainfall or water flow from international disaster forecasting and warning centers (if available).

2. Analyzing and evaluating current status

a) Analysis of rainfall trends: Accumulated average rainfall over the watershed from 1 to 2 weeks; average rainfall over the watershed, largest daily rainfall, highest rainfall intensity in 24 to 48 hours;

b) Analysis of upstream flood trends in the warning area;

c) Evaluation of current flash floods, landslides, and ground subsidence caused by rainfall or water flow in the warning area;

d) Determination of the current operation status of reservoirs in the warning area or upstream.

3. Implementation of Flash Flood, Landslide, and Ground Subsidence Warnings Caused by Rainfall or Water Flow

a) Commonly used warning schemes for flash floods, landslides, and ground subsidence caused by rainfall or water flow include:

a1) A scheme based on experience-based analysis methods, overlaying various types of maps: Topography, slope, flash flood risk zones, landslide risk zones;

a2) A scheme based on statistical methods;

a3) A scheme based on quantitative rainfall forecasts from numerical models, remote sensing information (if available), overlaying various types of maps: Topography, slope, flash flood risk zones, landslide risk zones;

a4) A scheme based on hydrological and hydraulic numerical modeling methods;

a5) Other methods (if available).

b) Flash flood, landslide, and ground subsidence warning schemes for rainfall or water flow used in the national hydro-meteorological forecasting and warning system are specified by the National Hydro-Meteorological Center.

4. Discussion on Flash Flood, Landslide, and Ground Subsidence Warnings Caused by Rainfall or Water Flow

a) Analyze and evaluate the reliability of warning results obtained from different methods used in recent bulletins.

b) Compile initial warning results from different methods and forecasters.

c) The person responsible for approving the bulletin selects the final warning result with the highest reliability.

5. Construction of Flash Flood, Landslide, and Ground Subsidence Warning Bulletins Caused by Rainfall or Water Flow

a) For the national hydro-meteorological forecasting and warning system

a1) Title of the flash flood, landslide, and ground subsidence warning bulletin for the affected area;

a2) Past rainfall trends, total rainfall, rainfall areas, rainfall intensity, and duration of rainfall in the forecast area;

a3) Assessment and warning of the possibility of flash floods, landslides, and ground subsidence caused by rainfall or water flow in the forecast area;

a4) Warning of disaster risk levels due to flash floods, landslides, and ground subsidence caused by rainfall or water flow, carried out according to Articles 11 and 12 of Decision No. 44/2014/QĐ-TTg dated August 15, 2014, of the Government Chairman detailing disaster risk levels;

a5) Time of bulletin issuance; time of subsequent bulletin issuance.

b) Depending on practical needs, organizations and individuals outside the national hydro-meteorological forecasting and warning system may independently define bulletin contents appropriately.

6. Dissemination of Flash Flood, Landslide, and Ground Subsidence Warning Bulletins Caused by Rainfall or Water Flow

a) National meteorological and hydrological forecasting and warning system

Flash flood, landslide, and ground subsidence warning bulletins caused by rainfall or water flow are disseminated according to Articles 24 and 25 of Decision No. 46/2014/QĐ-TTg dated August 15, 2014, of the Government Chairman regarding forecasting, warning, and disaster information dissemination.

7. Supplementing Flash Flood, Landslide, and Ground Subsidence Warning Bulletins Caused by Rainfall or Water Flow

In cases where unusual developments of flash floods, landslides, and ground subsidence are detected, supplementary warning bulletins should be issued beyond those regularly issued according to Article 15 of this Circular. The supplementation of bulletins shall be carried out according to the provisions from Clause 1 to Clause 6 of this Article.

8. Evaluation of Quality of Flash Flood, Landslide, and Ground Subsidence Warning Bulletins Caused by Rainfall or Water Flow

a) Evaluation content

a1) Evaluation of the timely and comprehensive implementation of the technical procedures for warning flash floods, landslides, and ground subsidence caused by rainfall or water flow;

a2) Evaluation of the completeness and timeliness of the provision of flash flood, landslide, and ground subsidence warning bulletins according to regulations;

a3) Evaluation of the quality of warning bulletins through the comparison of forecast factors with actual observations according to prescribed evaluation methods.

b) The National Hydro-Meteorological Center shall specify in detail the methods and criteria for evaluating flash flood, landslide, and ground subsidence warnings due to rain and river flow within the national hydro-meteorological forecasting and warning system.

c) Organizations and individuals not part of the national hydro-meteorological forecasting and warning system must comply with current regulations regarding forecast quality assessment.

Article 15. Frequency and Time of Issuing Flash Flood, Landslide, and Ground Subsidence Warnings Due to Rain and River Flow

Based on the characteristics, nature, possibility of occurrence, and time of occurrence of flash floods, landslides, and ground subsidence due to rain and river flow, meteorological and hydrological agencies issuing disaster forecasts and warnings shall issue warnings at appropriate times and frequencies for each specific case.

Chapter VI

TECHNICAL PROCEDURE FOR FORECASTING AND WARNING OF COLD AIR

Article 16. Content of Cold Air Forecasting and Warning

1. Temperature.

2. Strong Winds.

3. Extensive Heavy Rain.

4. Possibility of Severe Cold, Extreme Cold, Frost, and Salt Fog.

5. Large Waves.

Article 17. Technical Procedure

On the basis of observational data indicating the possibility of appearance or actual appearance of cold air signs, the following contents should be carried out:

1. Collecting and processing various types of information and data

a) Weather map data.

b) Synoptic observation data when cold air affects the country.

c) Cold air forecast data through numerical products.

d) Satellite, radar, and remote sensing observation data.

đ) Wind field and pressure field forecast data from numerical models.

e) Wave data from coastal and island meteorological marine observation stations.

2. Analyzing and evaluating current status

a) Analyze cold air on synoptic maps (Eurasia and South China Sea maps). Evaluate the activity of cold air over the past 24 hours and its potential intrusion into the country before 48 hours and 24 hours.

b) Analyze cold air on numerical products: Examine the movement of high-pressure centers or ridges with dense isobars affecting the northern border of the country after how long or when, thereby making appropriate forecasts.

c) Monitor and identify cold air on satellite cloud image channels: Southern China or Sichuan (China) region, within the latitude range from 23 degrees North to 30 degrees North, where cloud bands accompanied by weather conditions are present.of distributed along the latitude and moving southward.

3. Implement cold air forecasting and warning plans

a) Plans commonly used in cold air forecasting and warning and accompanying dangerous phenomena include:

a1) Cold air analysis and forecasting, severe cold, extreme cold, frost, and salt fog prediction based on forecast indicators 48 hours, 24 hours, and 12 hours in advance.

a2) Cold air analysis and forecasting, severe cold, extreme cold, frost, and salt fog prediction based on numerical products.

a3) Plans for forecasting and warning of extensive heavy rainfall accompanying cold air are implemented according to Clause 3, Article 8 of this Circular.

a4) Plans for forecasting and warning of large waves accompanying cold air are implemented according to Clause 3, Article 32 of this Circular.

b) Cold air forecasting and warning plans used in the national meteorological and hydrological forecasting and warning system are specified by the National Hydro-Meteorological Center.

4. Discuss Cold Air Forecasts and Warnings

a) Analyze and evaluate the reliability of forecast results using different methods in recent forecast and warning bulletins.

b) Synthesize initial forecast results from different methods and the opinions of forecasters.

c) The person responsible for issuing the bulletin selects the final forecast result with the highest reliability suitable for the forecast period.

5. Prepare Cold Air Forecast and Warning Bulletins

a) For the national hydro-meteorological forecasting and warning system

a1) Cold air forecast and warning bulletins are issued in the following cases:

- Northeast Monsoon Bulletin: Issued when there is a forecast of moderate or stronger northeast monsoon.

- Northeast Monsoon and Cold Bulletin: Issued when there is a forecast of moderate or stronger northeast monsoon and the possibility of severe cold or extreme cold, or when one-third of the stations in the delta region may experience severe cold.

- Strengthened Cold Air Bulletin: Issued when there is a forecast of strengthened cold air with moderate or stronger intensity.

- Strengthened Cold Air and Cold Bulletin: Issued when there is a forecast of strengthened cold air with moderate or stronger intensity and the possibility of severe cold or extreme cold, or when one-third of the stations in the delta region may experience severe cold.

- Severe Cold, Extreme Cold, Snowfall Warning Bulletin: Issued when there is a high-pressure center greater than 1065mb on the Eurasia map that could affect the country, combined with the activity of a trough or jet stream in the upper westerly wind belt.

- Frost, Ice Warning Bulletin Due to Cold Air: Issued when the temperature line at the 850mb synoptic map approaches the country's border and shows a downward trend towards the south.

a2) Contents of Cold Air Forecast and Warning Bulletins:

- Bulletin title;

- Recent cold air evolution from past to present regarding intensity, direction, and speed of movement, and weather changes (wind speed, temperature, precipitation);

- Forecast of cold air movement, impact level, and scope over the next 24 to 48 hours, and weather forecast including temperature, strong winds, extensive heavy rain, possibility of severe cold, extreme cold, frost, ice, and large waves in areas affected or about to be affected by cold air;

- Disaster risk level warning due to heavy rain, extreme cold, frost, and strong winds at sea, carried out according to Article 5, Article 8, and Article 15 of Decision No. 44/2014/QĐ-TTg dated August 15, 2014, of the Government detailing disaster risk levels;

- Time of bulletin implementation; time of issuance of the next bulletin.

b) Depending on practical needs, organizations and individuals outside the national hydro-meteorological forecasting and warning system may independently define bulletin contents appropriately.

6. Provide Cold Air Forecast and Warning Bulletins

a) National meteorological and hydrological forecasting and warning system

Cold air forecast and warning bulletins are provided according to Articles 24 and 25 of Decision No. 46/2014/QĐ-TTg dated August 15, 2014, of the Prime Minister on forecasting, warning, and 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 provide bulletins in accordance with practical needs.

7. Supplement cold air forecast and warning bulletin

In case of detecting unusual developments of cold air, additional cold air forecast and warning bulletins shall be issued outside those stipulated in Article 18 of this Circular, following the provisions from Clause 1 to Clause 6 of this Article.

8. Evaluation of cold air forecast and warning quality

a) Evaluation content

a1) Assessment of the timely and complete implementation of the contents prescribed in the technical procedure for cold air forecast and warning;

a2) Assessment of the completeness and timeliness of the provision of cold air forecast and warning bulletins as prescribed;

a3) Evaluation of the quality of warning bulletins through the comparison of forecast factors with actual observations according to prescribed evaluation methods.

b) The National Hydro-Meteorological Center shall detail the methods and criteria for evaluating cold air forecast and warning bulletins within the national hydro-meteorological forecast and warning system.

c) Organizations and individuals not part of the national hydro-meteorological forecasting and warning system must comply with current regulations regarding forecast quality assessment.

Article 18. Frequency and Time of Issuing Cold Air Bulletins

1. National Hydro-Meteorological Forecast and Warning System: Cold air forecast and warning bulletins shall be issued at least four times daily at 04:30, 10:00, 15:30, and 21:30.

2. Organizations and individuals engaged in cold air forecast and warning activities outside the national hydro-meteorological forecast and warning system shall independently determine the frequency and time of issuing cold air forecast and warning bulletins based on actual conditions.

Chapter VII

TECHNICAL PROCEDURE FOR SUNSHINE AND HEAT WAVE FORECAST AND WARNING

Article 19. Contents of Sunshine and Heat Wave Forecast and Warning

1. Temperature.

2. Relative humidity.

3. Affected area, time of occurrence, and time of cessation.

Article 20. Technical Procedure

Based on observational information and data indicating the possibility of or existing signs of heat waves, the following actions shall be carried out:

1. Collecting and processing various types of information and data

a) Weather map data.

b) Observational data on temperature and relative humidity;

c) Satellite data;

d) Data on heat waves from numerical model products.

2. Analyzing and evaluating current status

a) Assess and analyze the identification of weather patterns causing heat waves, including:

a1) A westward warm low-pressure system pushed south by the influence of cold air;

a2) A westward warm low-pressure system developing over the northern and central regions;

a3) Subtropical high pressure;

a4) Southwest low-level wind combined with subtropical high pressure aloft.

b) Determine the intensity of heat waves through the highest temperature and lowest relative humidity of the day.

c) Determine the scope of heat waves.

d) Determine the development of heat waves through intensity and scope over the next 24 to 48 hours.

3. Implementation of Heat Wave Forecast and Warning Plans

a) Common plans used in heat wave forecast and warning include:

a1) Plan based on atmospheric circulation;

a2) Plan based on satellite cloud image analysis;

a3) Plan based on numerical modeling method;

a4) Plan based on combined method;

a5) Other methods (if available).

b) Heat wave forecast and warning plans used in the national hydro-meteorological forecast and warning system are specified by the National Hydro-Meteorological Center.

4. Discussion on Heat Wave Forecast and Warning

a) Analyze and evaluate the reliability of forecast results using different methods in the most recent forecast bulletins.

b) Synthesize initial forecast results from different methods and the opinions of forecasters.

c) The person responsible for issuing the bulletin selects the most reliable final forecast result.

5. Construction of Heat Wave Forecast and Warning Bulletin

a) For the national hydro-meteorological forecasting and warning system

a1) Title of the bulletin;

a2) Summary information on the current heat wave status at the nearest time point (affected area, highest temperature, and lowest relative humidity);

a3) Forecast of affected area, intensity of heat waves, and expected end time of heat waves;

a4) Heat wave disaster risk level warning implemented according to Article 6 of Decision No. 44/2014/QD-TTg dated August 15, 2014, of the Government detailing the levels of natural disaster risks;

a5) Time of bulletin issuance; time of subsequent bulletin issuance.

b) Depending on practical needs, organizations and individuals outside the national hydro-meteorological forecasting and warning system may independently define bulletin contents appropriately.

6. Provision of Heat Wave Forecast and Warning Bulletins

a) National meteorological and hydrological forecasting and warning system

Heat wave forecast and warning bulletins shall be provided according to Articles 24 and 25 of Decision No. 46/2014/QD-TTg dated August 15, 2014, of the Government regarding forecast, warning, and dissemination of natural disasters.

7. Supplementing Heat Wave Forecast and Warning Bulletins

In case of detecting unusual developments of heat waves, additional heat wave forecast and warning bulletins shall be issued outside those stipulated in Article 21 of this Circular, following the provisions from Clause 1 to Clause 6 of this Article.

8. Evaluation of Heat Wave Forecast and Warning Quality

a) Evaluation content

a1) Assessment of the timely and complete implementation of the contents prescribed in the technical procedure for heat wave forecast and warning;

a2) Assessment of the completeness and timeliness of the provision of heat wave forecast and warning bulletins as prescribed;

a3) Assessment of bulletin forecast quality through comparison of forecast factors with actual observations.

b) The National Hydro-Meteorological Center shall detail the methods and criteria for evaluating heat wave forecast and warning bulletins within the national hydro-meteorological forecast and warning system.

c) Organizations and individuals not part of the national hydro-meteorological forecasting and warning system must comply with current regulations regarding forecast quality assessment.

Article 21. Frequency and Time of Issuing Heatwave Forecast and Warning Bulletins

1. National Meteorological and Hydrological Forecasting and Warning System: Heatwave forecast and warning bulletins shall be issued at least four times daily at 04:30, 10:00, 15:30, and 21:30.

2. Organizations and individuals engaged in forecasting and warning outside the national meteorological and hydrological forecasting and warning system shall independently determine the frequency and time for issuing bulletins.

Chapter VIII

TECHNICAL FORECASTING AND WARNING PROCEDURES FOR DROUGHT

Article 22. Content of Drought Forecast and Warning

1. Total rainfall in the forecast area.

2. Total water volume in the forecast area.

Article 23. Technical Procedures

Based on observational data and information indicating the possibility of or existing signs of drought, the following contents shall be carried out:

1. Collecting and processing various types of information and data

a) Collecting observational data on meteorological factors such as precipitation, evaporation, and humidity in the forecast area and its vicinity;

b) Collecting observational data on hydrological factors such as water levels and flow rates in the forecast area and its vicinity;

c) Collecting simulation and forecast data from global and regional models;

d) Collecting operational information and data on reservoirs and hydraulic works in the forecast area and its vicinity;

đ) Evaluating the completeness and accuracy of collected data and supplementing, adjusting, and standardizing the data;

e) Statistically analyzing meteorological characteristics including total rainfall in the watershed over the past 10 days, one month, three months, six months, or a specified period;

g) Statistically analyzing hydrological characteristics including total water volume and average flow rate in the watershed over the past 10 days, one month, three months, six months, or a specified period;

h) Updating data into forecasting tools such as statistical tables, charts, graphs, and predictive models.

2. Analyzing and evaluating current status

a) Analyzing weather trends:

a1) Statistically analyzing weather patterns causing prolonged dry spells affecting the forecast area;

a2) Statistically evaluating the shortfall in total rainfall in the forecast area compared to the long-term average for the same period or a similar year in the past.

b) Analyzing hydrological trends:

b1) Statistically analyzing water levels and flow rates on rivers within the watershed and forecast area;

b2) Noting the impact of reservoir operations on river flows within the watershed and forecast area;

b3) Statistically evaluating the shortfall and decline in total water volume in the watershed and forecast area over the past one month, three months, six months, or a specified period.

3. Implementing Drought Forecast and Warning Scenarios

a) Common scenarios used in drought forecasting and warning include:

a1) Scenarios commonly used in medium-term and long-term weather forecasting as stipulated in Clause 3 of Article 9 and Clause 3 of Article 10 of the Circular detailing technical procedures for meteorological and hydrological forecasting under normal conditions to determine total rainfall during the week (10 days) and monthly periods;

a2) Scenarios commonly used in seasonal weather forecasting as stipulated in Clause 3 of Article 14 of the Circular detailing technical procedures for meteorological and hydrological forecasting under normal conditions to determine total rainfall over a three-month and six-month period;

a3) Scenarios commonly used in medium-term and long-term hydrological forecasting as stipulated in Clause 3 of Article 11 and Clause 3 of Article 12 of the Circular detailing technical procedures for meteorological and hydrological forecasting under normal conditions to determine total water volume over a weekly (10-day) and monthly period;

a4) Scenarios commonly used in seasonal hydrological forecasting as stipulated in Clause 3 of Article 15 of the Circular detailing technical procedures for meteorological and hydrological forecasting under normal conditions to estimate total water volume over a three-month and six-month period;

b) Drought forecasting and warning scenarios used in the national meteorological and hydrological forecasting and warning system are prescribed by the National Hydro-meteorological Center.

4. Discussing Drought Forecast and Warning

a) Analyzing and evaluating the reliability of forecasting results using different methods in recent forecast and warning bulletins.

b) Compiling forecasting and warning results from various methods and forecasters' opinions.

c) The person responsible for issuing the bulletin selects the final forecast and warning result with the highest reliability.

5. Preparing Drought Forecast and Warning Bulletins

a) For the national hydro-meteorological forecasting and warning system

a1) Title of the drought forecast and warning bulletin accompanied by the expected time, river basin, or area at risk of drought impact;

a2) Trends in total rainfall and total water volume in the forecast area (in table, chart, or map form) over the past 10 days, one month, three months, six months, or a specified period;

a3) Percentage (%) shortfall in total rainfall and total water volume over the past 10 days, one month, three months, six months, or a specified period compared to the long-term average for the same period;

a4) Assessment of rainfall and flow trends in the forecast area over the next 10 days, one month, three months, six months, or a specified period;

a5) Forecast values compiled in table, graph, or map form;

a6) Comparing the percentage (%) of total forecast rainfall and water volume with the long-term average for the same period;

a7) Drought disaster risk level warnings implemented according to Article 7 of Decision No. 44/2014/QĐ-TTg dated August 15, 2014, of the Government detailing disaster risk levels;

a8) Time of bulletin preparation; time of issuance of the next bulletin.

b) Depending on practical needs, organizations and individuals outside the national hydro-meteorological forecasting and warning system may independently define bulletin contents appropriately.

6. Providing Drought Forecast and Warning Bulletins

a) National meteorological and hydrological forecasting and warning system

Drought forecast and warning bulletins are provided according to Articles 24 and 25 of Decision No. 46/2014/QĐ-TTg dated August 15, 2014, of the Government regarding disaster forecasting, warning, and dissemination.

b) Organizations and individuals not part of the national meteorological and hydrological forecasting and warning system independently specify the list of addresses to which bulletins will be provided consistent based on actual needs.

7. Supplementing Drought Forecast and Warning Bulletins

In in case Upon detecting unusual drought developments, additional drought forecast and warning bulletins shall be issued beyond those stipulated in Article 24 of this Circular. The issuance of such additional bulletins shall comply with the provisions from Clause 1 to Clause 6 of this Article.

8. Evaluation of drought forecast and warning quality

a) Content of evaluation:

a1) Assessment of the timely and complete implementation of the contents prescribed in the technical procedure for drought forecasting and warning;

a2) Assessment of the completeness and timeliness of the provision of drought forecast and warning bulletins as prescribed;

a3) Quality assessment of the forecast and warning bulletins through comparison of predictive factors with actual observations.

b) The National Hydro-meteorological Center shall detail the methods and criteria for evaluating drought forecast and warning bulletins within the national hydro-meteorological forecasting and warning system.

c) Organizations and individuals not part of the national hydro-meteorological forecasting and warning system must comply with current regulations regarding forecast quality assessment.

Article 24. Frequency and Time of Issuing Drought Forecast and Warning Bulletins

1. National Hydro-meteorological Forecasting and Warning System: The frequency and time of issuing drought forecast and warning bulletins shall be at least once every ten days, published at 15:30 during periods when regions and basins are at risk of water shortages due to insufficient rainfall or water sources. Additionally, drought forecasts and warnings are integrated into short-term weather forecast and warning bulletins; long-term weather, hydrological, and marine forecast and warning bulletins; seasonal weather and hydrological forecast and warning bulletins, which are issued according to the frequency and times specified in Clause 1 of Article 5 of the Circular on Technical Procedures for Routine Weather Forecasting and Warning.

Chapter IX

TECHNICAL PROCEDURE FOR SALINITY INTRUSION FORECASTING AND WARNING

Article 25. Contents of Salinity Intrusion Forecasting and Warning

1. Maximum salinity level.

2. Time of occurrence of maximum salinity level.

3. Affected range where salinity reaches 4‰ or higher.

Article 26. Technical Procedure

Based on observed data indicating the possibility or occurrence of signs of salinity intrusion, the following actions should be taken:

1. Collecting and processing various types of information and data

a) Collect rainfall and temperature data from the basin and area under forecast over the recent period.

b) Analyze water levels and flow rates at upstream stations in the basin and area under forecast over the recent period.

c) Analyze tidal changes in the basin and area under forecast over the recent period. Collect observation data from marine stations affecting the forecast and warning areas.

d) Collecting operational information and data on reservoirs and hydraulic works in the forecast area and its vicinity;

d) Gather salinity measurement data from salinity monitoring stations in the basin and area under forecast and nearby locations.

e) Evaluate the completeness and accuracy of collected data and supplement, adjust, and standardize the data.

g) Information and planned water usage needs in the basin and area under forecast, as well as agricultural, fisheries, and other socio-economic activities' water usage needs.

h) Update data into forecasting tools such as statistical tables, charts, graphs, and salinity prediction models.

2. Analyzing and evaluating current status

a) Analyzing weather trends:

a1) Changes in rainfall volume and spatial distribution over time.

a2) Rainfall forecast information in the basin and area under forecast for the forecast period.

b) Analyzing hydrological trends:

b1) Analyze water level and flow rate trends in the basin and area under forecast.

b2) Analyze the impact of reservoir operation, hydropower, and irrigation works on flow in the basin and area under forecast.

b3) Analyze trends and changes in salinity intrusion and maximum salinity levels in the basin and area under forecast over the recent period.

b4) Analyze the influence of tidal regimes on the extent of salinity intrusion.

b5) Compile information on hazardous events such as high tides and sea-level rise that affect salinity intrusion in the forecast area.

3. Implementation of Salinity Intrusion Forecasting and Warning Plans

a) Commonly used plans in salinity intrusion forecasting and warning include:

a1) Traditional method-based plans: Correlation maps, statistics...

a2) Mathematical model-based plans.

b) Salinity intrusion forecasting and warning plans used in the national hydro-meteorological forecasting and warning system are defined by the National Hydro-meteorological Center.

4. Discussion on Salinity Intrusion Forecasting and Warning

a) Assess the reliability of forecasting results using different methods.

b) Evaluate the reliability of the forecasting model.

c) Assess the stability of forecasting results from the model.

d) Synthesize forecasting and warning results from various methods and forecasters' opinions.

e) The person responsible for issuing the bulletin selects the final forecasting result with the highest reliability.

5. Construction of Salinity Intrusion Forecasting and Warning Bulletin

a) For the national hydro-meteorological forecasting and warning system

a1) Title of the salinity intrusion forecasting and warning bulletin including the expected time, name of the river basin or region at risk of salinity intrusion.

a2) Trend of salinity intrusion, forecast of maximum salinity level, and time of occurrence.

a3) Affected range and duration of salinity reaching 4‰ or higher; distance affected from the main river mouth, communes, and districts within the affected range.

a4) Duration of salinity reaching 4‰ or higher.

a5) Risk level warning for natural disasters caused by salinity intrusion, implemented according to Article 13 of Decision No. 44/2014/QĐ-TTg dated August 15, 2014, of the Government Chairman regarding disaster risk levels.

a6) Bulletin issuance time and time for the next bulletin.

b) Depending on practical needs, organizations and individuals outside the national hydro-meteorological forecasting and warning system may independently define bulletin contents appropriately.

6. Provision of Salinity Intrusion Forecasting and Warning Bulletins

a) National meteorological and hydrological forecasting and warning system

Salinity intrusion forecasting and warning bulletins are provided according to Articles 24 and 25 of Decision No. 46/2014/QĐ-TTg dated August 15, 2014, of the Government Chairman regarding forecasting, warning, and disseminating natural disaster information.

7. Supplemental Salinity Intrusion Forecasting and Warning Bulletins

In cases of unusual salinity intrusion developments, additional salinity intrusion forecast and warning bulletins should be issued beyond those stipulated in Article 27 of this Circular. The issuance of such additional bulletins shall comply with the provisions from Clause 1 to Clause 6 of this Article. MANAGEMENT AND USE OF DEPOSITS AT THE ENVIRONMENT PROTECTION FUND forecast and warning bulletins for saline intrusion, in addition to those issued in accordance with Article 27 of this Circular. The supplementation of these bulletins shall be carried out in accordance with the provisions from Clause 1 to Clause 6 of this Article.

8. Evaluation of Salinity Intrusion Forecasting and Warning Quality

a) Evaluation content

a1) Assessment of the timely and complete implementation of the contents prescribed in the technical procedure for salinity intrusion forecasting and warning.

a2) Assessment of the completeness and timeliness of the provision of salinity intrusion forecast and warning bulletins as prescribed.

a3) Assessment of bulletin forecast quality through comparison of forecast factors with actual observations.

b) The National Meteorological and Hydrological Centre shall specify in detail the methods and criteria for evaluating forecast and warning bulletins on saline intrusion within the national meteorological and hydrological forecast and warning system.

c) Organizations and individuals not part of the national hydro-meteorological forecasting and warning system must comply with current regulations regarding forecast quality assessment.

Article 27. Frequency and Time of Issuing Forecast and Warning Bulletins on Saline Intrusion

1. For the national meteorological and hydrological forecast and warning system: The frequency and time of issuing forecast and warning bulletins on saline intrusion shall be at least once every ten days, issued at 15:30 during periods when there is a risk of saline intrusion in relevant areas. Additionally, forecasts and warnings on saline intrusion will also be included in long-term weather, hydrological, and marine weather forecast and warning bulletins issued according to the frequency and time specified in Clause 1 of Article 5 of the Circular stipulating the Technical Procedures for Routine Meteorological and Hydrological Forecasting.

Chapter X

TECHNICAL PROCEDURES FOR WARNING OF THUNDERSTORMS, LIGHTNING, GUSTS, FUNNEL CLOUDS, HAIL, AND HEAVY RAINFALL

Article 28. Content of Warnings on Thunderstorms, Lightning, Gusts, Funnel Clouds, Hail, and Heavy Rainfall

1. Possibility of occurrence of thunderstorms, lightning, gusts, funnel clouds, hail, and heavy rainfall.

2. Time of occurrence.

3. Affected area.

4. Amount of rainfall.

Article 29. Technical Procedures

Based on observational data indicating the possibility of or actual appearance of signs of thunderstorms, lightning, gusts, funnel clouds, hail, and heavy rainfall, the following actions should be taken:

1. Collecting and processing various types of information and data

a) Satellite meteorological data from infrared, near-infrared, visible spectrum channels, and secondary products: Analysis of convective clouds, rainfall estimates, cloud classification, air mass analysis, natural color composite, microphysics of clouds;

b) Weather radar data and combined radar image products, rainfall estimates within the warning area and adjacent regions;

c) Lightning location data within the warning area (if available);

d) Surface observation data (including automatic observations), radio reconnaissance within the warning area and adjacent regions;

đ) High-resolution regional model forecast value products, point forecasts;

e) Short-range weather forecast bulletins, thunderstorm, lightning, gust, funnel cloud, hail, and heavy rainfall warning bulletins (if available);

g) Evaluating the completeness and accuracy of collected data and supplementing, correcting, and standardizing the data.

2. Analyzing and evaluating current status

a) Analyze a series of satellite images in priority order (visible spectrum, infrared, near-infrared, water vapor) and secondary products (convective cloud analysis, rainfall estimates, cloud classification, air mass analysis, natural color composite, microphysics of clouds) six hours prior to the present to determine areas of convective clouds that may cause thunderstorms, lightning, gusts, funnel clouds, hail, and heavy rainfall in the warning area;

b) Analyze a series of weather radar data (reflectivity, direction, speed, wind, rainfall estimates) six hours prior to the present with priority given to data from radars near the warning area to re-determine areas of convective clouds that may cause thunderstorms, lightning, gusts, funnel clouds, hail, and heavy rainfall in the warning area;

c) Analyze lightning location data regarding intensity and density (if available);

d) Direct visual observation of cloud types in the sky and assessment of the development of convective clouds (in cases where permitted);

3. Implementing warnings on thunderstorms, lightning, gusts, funnel clouds, hail, and heavy rainfall

a) Case of thunderstorms and lightning forming immediately in the warning area

When analyzing satellite, radar, and lightning location data, if convective clouds begin to form in the warning area; the top temperature of clouds on infrared and near-infrared images shows a continuous sharp decrease; the albedo reflectance on visible spectrum images increases rapidly; radar reflectivity is high and increasing rapidly; lightning strikes appear on the lightning location map, then conclude on the possibility and degree of occurrence of thunderstorms and lightning, and proceed to issue and provide the bulletin as prescribed in Clauses 4 and 5 of this Article.

b) Case of thunderstorms and lightning moving into the warning area from outside

When analyzing satellite, radar, and lightning location data, if convective clouds from outside show a tendency to move into the warning area, the following steps should be taken:

b1) Identify the areas of convective clouds;

b2) Determine the level of development of convective clouds based on the analysis of the evolution of cloud top temperatures, albedo reflectance (for satellite images), radar reflectivity (for radar images), lightning intensity, and lightning strike density (for lightning location data); in the Field of Teachers and Educational Institution Managers b3) Determine the direction and speed of movement of the convective clouds; conclude on the possibility and degree of occurrence of thunderstorms and lightning in the warning areas.

c) Identifying dangerous weather phenomena: Gusts, funnel clouds, hail, and heavy rainfall

c1) Based on the evaluation of the development speed of convective clouds and their identification signs on radar and satellite images, assess the possibility of occurrence of dangerous weather phenomena: gusts, funnel clouds, and hail;

c2) Based on radar, satellite, and automatic rainfall data, determine the possibility of occurrence of heavy rainfall (range, intensity).

4. Preparing the warning bulletin on thunderstorms, lightning, gusts, funnel clouds, hail, and heavy rainfall

a2) The content of the warning bulletin includes: Current situation information, analysis of phenomenon development, start time of the phenomenon, affected area, and impact level;

a) For the national hydro-meteorological forecasting and warning system

a1) Title of the bulletin;

a3) The warning level of disaster risks due to funnel clouds, lightning, hail, and heavy rainfall is implemented according to Articles 4 and 5 of Decision No. 44/2014/QĐ-TTg dated August 15, 2014, of the Government Chairman detailing the disaster risk warning levels;

a4) Time of issuing the bulletin.

5. Providing the warning bulletin on thunderstorms, lightning, gusts, funnel clouds, hail, and heavy rainfall

b) Depending on practical needs, organizations and individuals outside the national hydro-meteorological forecasting and warning system may independently define bulletin contents appropriately.

Warning bulletins on thunderstorms, lightning, gusts, funnel clouds, hail, and heavy rainfall are provided according to Articles 24 and 25 of Decision No. 46/2014/QĐ-TTg dated August 15, 2014, of the Government Chairman on forecasting, warning, and transmitting disaster information.

a) National meteorological and hydrological forecasting and warning system

6. Supplementing the warning bulletin on thunderstorms, lightning, gusts, funnel clouds, hail, and heavy rainfall

6. Supplementing warning bulletins for thunderstorms, lightning, hail, tornadoes, and localized heavy rainfall.

In cases where phenomena such as thunderstorms, lightning, tornadoes, whirlwinds, hail, and localized heavy rainfall with unusual developments are detected, it is necessary to supplement warnings for thunderstorms, lightning, tornadoes, whirlwinds, hail, and localized heavy rainfall beyond those issued according to Article 30 of this Circular. The supplementation of the warning bulletin shall be carried out in accordance with the provisions from Clause 1 to Clause 5 of this Article.

7. Evaluation of warnings for thunderstorms, lightning, tornadoes, whirlwinds, hail, and localized heavy rainfall

a) Content of evaluation:

a1) Evaluate the full and timely implementation of the contents stipulated in the technical procedure for warning thunderstorms, lightning, tornadoes, whirlwinds, hail, and localized heavy rainfall.

a2) Evaluate the completeness and timeliness of the provision of warnings for thunderstorms, lightning, tornadoes, whirlwinds, hail, and localized heavy rainfall as prescribed.

a3) Assess the quality of forecast and warning bulletins through comparisons between observed phenomena of thunderstorms, lightning, tornadoes, whirlwinds, hail, and localized heavy rainfall and actual observations, information from localities, and mass media.

b) The National Hydro-Meteorological Center shall specify in detail the methods and criteria for evaluating warnings for thunderstorms, lightning, tornadoes, whirlwinds, hail, and localized heavy rainfall within the national weather forecasting and warning system.

c) Organizations and individuals not part of the national hydro-meteorological forecasting and warning system must comply with current regulations regarding forecast quality assessment.

Article 30. Frequency and issuance of warnings for thunderstorms, lightning, tornadoes, whirlwinds, hail, and localized heavy rainfall time issuing warning bulletins for thunderstorms, lightning, hail, tornadoes, and localized heavy rainfall.

1. Warnings for thunderstorms, lightning, tornadoes, whirlwinds, hail, and localized heavy rainfall issued by the national weather forecasting and warning system shall be implemented when there is a possibility of these phenomena occurring in the warning area.

2. Organizations and individuals engaged in forecasting and warning that are not part of the national weather forecasting and warning system shall independently determine the frequency and timing of issuing warnings for thunderstorms, lightning, tornadoes, whirlwinds, hail, and localized heavy rainfall.

Chapter XI

TECHNICAL PROCEDURE FOR FORECASTING AND WARNING OF SEA FOG, LARGE WAVES, WATER RISE IN TROPICAL DEPRESSIONS, STORMS, SEASONAL WINDS, AND SPRING TIDES

Article 31. Content of forecasts and warnings for sea fog, large waves, water rise, and spring tides

1. Areas where sea fog appears, reducing visibility significantly.

2. Height and direction of large waves.

3. Areas affected by large waves.

4. Height and time of occurrence of the highest water level rise.

5. Distribution of the highest water level rise.

6. Risk of flooding along the coast due to water rise combined with tidal currents.

7. Height and time of occurrence of the highest total water level.

8. Areas affected by spring tides.

Article 32. Technical procedures

Based on observational data indicating the potential or actual appearance of signs of sea fog, large waves, water rise, and spring tides, the following actions should be taken:

1. Collecting and processing various types of information and data

a) Collecting information and warnings about marine weather (monsoon winds, tropical depressions, storms, low-pressure areas, weather patterns potentially causing abnormal water rises, thunderstorms, whirlwinds, and sea fog).

b) Collecting forecast wind field and pressure data from numerical weather prediction models.

c) Collecting forecast parameters for tropical depressions and storms (if applicable).

d) Collecting observational data on sea fog, temperature, dew point temperature, wind, pressure, waves, and water levels at meteorological stations in the forecast area.

đ) Collecting wave observation data from buoys and radar stations in the forecast area (if available).

e) Collecting wave observation data from ships operating in the forecast area (if available).

g) Collecting wave forecast data issued by other domestic and international forecasting centers.

h) Collecting water rise forecast data issued by other domestic and international forecasting centers.

i) Collecting information on tide forecasts when implementing short-term and very short-term hydro-meteorological forecasting procedures as specified in Article 8 of the Circular detailing technical procedures for normal weather forecasting.

k) Evaluating the completeness and accuracy of collected data, and supplementing, correcting, and standardizing the data.

2. Analyzing and assessing the current status of sea fog, spring tides, large waves, and water rise

a) Analyzing and determining areas affected by large waves.

b) Analyzing and determining areas experiencing high tides, the magnitude and time of occurrence of high water levels.

c) Analyzing and assessing the current status and trends of weather patterns over the sea: intensity, movement direction of storms, tropical depressions, low-pressure areas, and monsoon wind strength, atmospheric pressure patterns that may cause abnormal water rises.

d) Based on objective analysis maps and forecast maps obtained from operational numerical weather prediction models, monitor and identify hazardous weather areas currently or likely to form within 12, 24, 36, 48, or 72 hours. , Đ currently existing or likely to form within 12, 24, 36, 48, or 72 hours;

e) Monitoring various synoptic charts, evaluating the difference between temperature and dew point temperature, thereby assessing the likelihood of sea fog formation and development.

f) Regularly reviewing products extracted from satellite cloud imagery channels regarding cloud structure, extent, type, and its temporal development, combined with cloud image analysis software and synoptic map systems to determine which cloud system it belongs to and whether it can cause sea fog.

3. Implementing forecast and warning plans for sea fog, spring tides, large waves, and water rise

a) Forecast and warning plans commonly used include:

a1) Plans for forecasting and warning sea fog

- Plan based on synoptic analysis method and experience;

- Plan based on remote sensing information analysis and forecast results;

- Plans based on the analysis and results from numerical models.

a2) Plans for forecasting and warning waves

- Wave height forecasting:

+ Forecasting waves in tropical depressions and storms using graphical methods.

+ Forecasting waves during monsoons using analytical formulas.

- Forecasting wave height and direction:

+ Forecasting wave height and direction using numerical models with wind fields and pressure from storm analytical models (based on tropical depression and storm forecast parameters).

+ Forecasting wave height and direction using numerical models with meteorological fields from numerical weather prediction models.

a3) Plans for forecasting and warning water rise

- Forecasting water rise height using analytical formulas.

- Forecasting the height of the flood tide based on meteorological input data from numerical weather prediction models;

- Forecasting the height of the flood tide using parameters for tropical depression and typhoon forecasts;

a4) Forecasting and warning plan for high tides;

Based on information about tidal predictions as stipulated in Article 8 of the Circular detailing the Technical Procedure for Routine Meteorological and Hydrological Forecasting, and information about wind-induced flood tide forecasts at Point a3 Clause 3 of this Article, forecasters provide forecasting and warning information regarding high tides.

b) Forecasting and warning plans for sea fog, high tides, large waves, and flood tides are specified by the National Hydro-meteorological Center for use in the national meteorological and hydrological forecasting and warning system.

4. Discussion on forecasting and warning for sea fog, high tides, large waves, and flood tides

a) Analyze and evaluate the reliability of forecast results using different methods in recent forecast and warning bulletins.

b) Synthesize initial forecast results from different methods and the opinions of forecasters.

c) The person responsible for issuing the bulletin selects the most reliable final forecast result.

5. Developing forecast and warning bulletins for sea fog, high tides, large waves, and flood tides

a) For the national hydro-meteorological forecasting and warning system

a1) Forecast and warning bulletin for sea fog

- Bulletin title;

- The area where sea fog appears, the possibility of its duration, and the reduction in visibility to what extent;

- Sea fog disaster risk level warnings are carried out according to the provisions of Article 9 of Decision No. 44/2014/QĐ-TTg dated August 15, 2014, detailing disaster risk levels issued by the Prime Minister;

- Time of bulletin implementation; time of issuance of the next bulletin.

a2) Forecast and warning bulletin for large waves at sea

- Bulletin title;

- Content includes the highest wave height, predominant wave direction, and warning areas for large waves;

- Time of bulletin implementation; time of issuance of the next bulletin.

a3) Forecast and warning bulletin for flood tides

- Bulletin title;

- Information on the height and time of occurrence of the highest flood tide, the highest total water level, spatial distribution map of the highest flood tide around the typhoon landing area, and assessment of the risk of coastal flooding due to flood tides combined with tides;

- Flood tide disaster risk level warnings are carried out according to the provisions of Article 14 of Decision No. 44/2014/QĐ-TTg dated August 15, 2014, detailing disaster risk levels issued by the Prime Minister;

- Time of bulletin implementation; time of issuance of the next bulletin.

a4) Forecast and warning bulletin for high tides

- Bulletin title;

- Information on the height and time of occurrence of high tides, and assessment of the risk of coastal flooding due to high tides;

- Time of bulletin issuance; time of subsequent bulletin issuance (if there is a possibility of occurrence);

b) Depending on practical needs, organizations and individuals outside the national hydro-meteorological forecasting and warning system may independently define bulletin contents appropriately.

6. Providing forecast and warning bulletins for sea fog, large waves, flood tides, and high tides

a) National meteorological and hydrological forecasting and warning system

Forecast and warning bulletins for sea fog, large waves, flood tides, and high tides are provided according to the provisions of Articles 24 and 25 of Decision No. 46/2014/QĐ-TTg dated August 15, 2014, detailing forecasting, warning, and disseminating disaster information issued by the Prime Minister.

7. Supplementing forecast and warning bulletins for sea fog, large waves, flood tides, and high tides

In case of unusual developments in sea fog, large waves, flood tides, and high tides, supplementary forecast and warning bulletins for sea fog, large waves, flood tides, and high tides should be issued outside those issued according to the provisions of Article 33 of this Circular. Supplementary bulletins shall be issued according to the provisions from Clause 1 to Clause 6 of this Article.

8. Evaluating the quality of forecasting and warning for sea fog, large waves, flood tides, and high tides

a) Evaluation content

a1) Evaluation of the full and timely implementation of the technical procedures for forecasting and warning of sea fog, large waves, and flood tides during tropical depressions, typhoons, monsoons, and high tides;

a2) Evaluation of the completeness and timeliness of providing forecast and warning bulletins for sea fog, large waves, flood tides, and high tides as prescribed;

a3) Quality evaluation of forecast and warning bulletins through comparison of forecast factors with actual observations according to specified evaluation methods.

b) The National Hydro-meteorological Center specifies detailed methods and criteria for evaluating forecast and warning bulletins for sea fog, large waves, flood tides, and high tides within the national meteorological and hydrological forecasting and warning system.

c) Organizations and individuals not part of the national hydro-meteorological forecasting and warning system must comply with current regulations regarding forecast quality assessment.

Article 33. Frequency and issuance of fog over sea, large waves, water rise, and spring tide bulletins time issuing fog warnings over the sea, large waves, high tides, and spring tides.

1. National weather and hydrological forecasting and warning system:

a) Fog over sea and spring tide forecast and warning bulletins shall be issued at least once daily at 15:30.

b) Large wave and water rise forecast and warning bulletins during the Northeast Monsoon shall be issued with the same frequency and time as cold air forecast and warning bulletins prescribed in Clause 1, Article 18 of this Circular.

c) Large wave and water rise forecast and warning bulletins during tropical depression and typhoon shall be issued with the same frequency and time as tropical depression and typhoon forecast and warning bulletins prescribed in Article 12 of Decision No. 46/2014/QĐ-TTg dated August 15, 2014 of the Government on weather and hydrological forecasting, warning, and disaster information dissemination.

2. Organizations and individuals engaged in weather and hydrological forecasting and warning outside the national weather and hydrological forecasting and warning system shall independently determine the frequency and time for issuing fog over sea, spring tide forecast and warning bulletins; large wave and water rise forecast and warning bulletins during the Northeast Monsoon.

Chapter XII

IMPLEMENTING PROVISIONS

Article 34. Effective Date

1. This Circular takes effect from February 10, 2017.

2. The Circular No. 14/2010/TT-BTNMT dated July 29, 2010 of the Ministry of Natural Resources and Environment on Flood Forecasting Procedures and the Circular No. 15/2010/TT-BTNMT dated July 30, 2010 of the Ministry of Natural Resources and Environment on Tropical Depression and Typhoon Forecasting Procedures are hereby abolished.

Article 35. Responsibility for Implementation

1. The General Director of the National Hydro-meteorological Center shall be responsible for guiding subordinate units to implement the contents stipulated in this Circular.

2. The Director of the Meteorology, Hydrology and Climate Change Department shall monitor and inspect the implementation of this Circular.

3. Ministries, ministerial-level agencies, of the National Assembly; provincial-level People's Committees under the central government and relevant agencies, organization shall be responsible for implementing this Circular.

4. In the course of implementing this Circular, if there are difficulties or obstacles, agencies, organizationand individuals shall promptly report to the Ministry of Natural Resources and Environment for study, amendment, and supplementation./.

Place of Receipt:
- Prime Minister and Deputy Prime Ministers;
- Ministries, agencies equivalent to ministries, and government agencies;
- National Assembly's Office;
- President's Office;
- Central Party Office;
- Supreme People's Court;
- Supreme People's Procuracy;
- Legal Documents Supervision Bureau (Ministry of Justice);
- Provincial and municipal People's Committees directly under the central government;
- Provincial Departments of Natural Resources and Environment under central cities and provinces;
- Official Gazette; Government Electronic Portal;
- Ministry of Natural Resources and Environment website;
- To be filed: VT, Planning and Finance Department, Science and Technology Department, Meteorology, Hydrology and Climate Change Department. M(200).

DEPUTY MINISTER
DEPUTY MINISTER

Chu Pham Ngoc Hien

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