Integrated Warning Service System in Czech Hydrometeorological Institute

Marjan Sandev

Czech Hydrometeorological Institute Prague, email: [email protected]

Abstract

CHMI‘s warning service is a component of Integrated Rescue System of the Czech Republic supplying warnings for the territory of the Czech Republic for both meteorological and hydrological risks. Its main purpose is to inform and warn authorities, media, people and other users of hydrometeorological data about probability of dangerous weather phenomena and contribute to save human lives and property.

This service is carrying out by meteorological and hydrological forecasting section (Central and Regional Forecasting Offices) of CHMI in co-operation with Military Weather Service of Army of the Czech Republic using concept of Integrated Warning Service System. Warning information from IWSS is available in both ASCI and XML formats immediately after their issuing. Special warning text is send to Integrated Rescue Service who disseminates it to local authorities. Other direct users of IWSS warnings are River authorities or media. Warning is also available for general public trough CHMI web page in graphical and tabular format. Notifying message for neighboring national meteorological services (, , , and ) is prepared and distributed automatically by email when warning information is issued. SMS information is also prepared for some users. Last year CHMI has become a new participant in EMMA project (Meteoalarm) for visualization of warning information on web pages. Experience shows the importance of education of local authorities, media and other users for better understanding and interpretation of warning information.

Key Words: Integrated Warning Service System, dangerous phenomena, warning information

Introduction Czech Hydrometeorological Institute (CHMI) is authorized, besides other meteorological, hydrological and air quality control tasks, for warning service of dangerous meteorological and hydrological phenomena for the territory of the Czech Republic. This service is carrying out primarily by Integrated Warning Service System (IWSS), which was putted into operation in February 2000. After experience from the following years, especially large floods in 2002, the system was innovated (according to Davidson et al., 2005). New version is operated since January 2006. Innovated system contributes successfully to reduce impacts of dangerous meteorological and hydrological phenomena.

IWSS was developed at CHMI in collaboration with Military Weather Service (MWS) of the Czech Republic. Common service of both institutes has increased a quality of warning information, and removed double counting or/and substantial differences in warning information.

In addition to IWSS, CHMI purvey forecasts of dangerous events to other special users as road maintenance authorities or media. Unlike of that forecasts, the IWSS unambiguously defines rules and criterions for issuing of warning information for meteorological and hydrological events and becomes a basis of CHMI warning system.

Issuing and distribution of warning information Forecasting service of CHMI is provided by Central Forecasting Office (CFO) and six Regional Forecasting Offices (RFO). All of them have meteorological and hydrological division cooperating closely together. Warning information of IWSS are issued by CFO only after regular, or if it is necessary, after irregular conferences between CFO and RFOs as well as with MWS. In case of flood the conference is led by hydrologist on duty.

IWSS is served by senior forecaster of CFO, who is responsible for assembling and timely issuing of warning. IWSS outputs are generated in ASCI and XML formats and their dissemination is automatic. All users receive information immediately after its issuing via GTS, mail, fax or SMS. Warning

______BALWOIS 2008 – Ohrid, Republic of Macedonia – 27, 31 May 2008 1/7 information is also presented at special CHMI web page (Fig.1). Concerning the floods, there is a special web page of CHMI providing not only the warning but also other related information (Fig. 2).

Figure 1. Web page of Czech Hydrometeorological Institute for visualization of warning information for territory of the Czech Republic (http://pocasi.chmi.cz)

Figure 2. Web page of CHMI providing hydrological data and information for territory of the Czech Republic (http://hydro.chmi.cz/hpps)

Czech Republic has become a co-operative member of the EUMETNET (Network of European Meteorological Services) project METEOALARM in September 2007. Project provides internet web page (http://www.meteoalarm.eu/) giving quick overview of warnings on dangerous phenomena in

______BALWOIS 2008 – Ohrid, Republic of Macedonia – 27, 31 May 2008 2/7 Europe. The page is intended primarily for general public highlight European regions with current warning. Floods warning are planed to be implemented in 2009.

The main recipient of CHMI warnings is Central Fire Rescue Office which is responsible for further dissemination of warning trough its regional offices. Flood relevant warnings (including heavy precipitation and thunderstorm warnings) are sent directly to National Flood Authorities (Ministry of Environment) and River authorities (Fig. 3).

River & Basin Authorities CHMI

CFO National Flood Central Authorities Firerescue Office RFOs

Regional Firerescue Ofices

Radio TV Regional & Internet Local Flood Teletext Authorities Press

Figure 3. Distribution of hydrometeorological warning information in the Czech Republic

Concept of IWSS Warning information of IWSS is issued for 26 dangerous hydrometeorological parameters and phenomena divided into 7 categories (Tab. 1).

I. Temperature and humidity conditions II. Wind III. Snowfall and snow phenomena linked with increased of wind speed

IV. Freezing phenomena V. Thunderstorms with accompanying phenomena VI. Rainfall VII. Flood phenomena

Table 1. Categories of dangerous hydrometeorological parameters and phenomena using in CHMI warning system

Warning is issued for phenomena, which could lead to very different consequences and damages, in extreme cases with catastrophic effects. Therefore each phenomenon is assigned to one of 3 levels of danger (Tab. 2). In agreement with international projects of visualization danger weather on web pages (Davidson et al., 2003), each level has its own color. There are 14 administrative districts in the Czech Republic (with area usually about 5 000 km2) for which warnings are specified by colors according to degree of danger. If two or more dangerous phenomena of different level of danger are forecasted for one region, color corresponding to the highest one is used.

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Level of risk Class of risk

None N green

Low L yellow High H orange

Extreme E red

Table 2. Levels of danger used in the IWSS

CHMI issues two types of warning information: 1) forecasting warning information, 2) information about occurrence of extreme events.

Forecasting warning information is issued, if any of dangerous weather phenomena is forecasted or even if it has recently occurred and it is supposed its further duration. Warning information defines the beginning and the end of validity. Our aim is to provide 12 to 48 hours lead-time of warning. Anytime only one forecasting warning information can be valid. Therefore issuing of new warning automatically cancels the previous one.

Information about occurrence of extreme events is issued in a case of occurrence (measured, observed or objectively detected) of danger event with extreme level of risk and rapid progression like snow storm, severe thunderstorms, extreme precipitation or flood danger (reaching the highest flood stage). It is issued to notify about its occurrence or to describe its development up to three hours ahead. In such a case more information could be valid in the same time.

If warning information contains any of hydrological phenomena (see Tab. 2, category V. to VII.), parallel warning information of Flood Forecasting Service (FFS) of CHMI is issued. That warning is distributed to different list of users demanding only flood warnings. During floods FFS prepares special information bulletins with the main aim to provide deeper description of hydrological situation and forecasts. Information about some other hydrological aspects or phenomena (ice jams on rivers, snow reserve or drought etc.) could be also distributed using those reports.

Methodology of forecasting and warning system The basic component of each weather warning system is monitoring of hydrometeorological parameters including dangerous phenomena. For that purpose, CHMI warning service has developed some operational applications.

PCMONI software monitors all meteorological data from different sources: bulletins and data from Global Telecommunication System (GTS), rain & water gauges (degrees of flood stages), radars etc. and automatically compares them to thresholds for dangerous events. In case of threshold overshooting meteorologist is immediately aware of that.

Radar precipitation estimates are merged in real-time with automatic rain gauge measurements. Radar precipitation estimates are calculated from 3 types of products: maximum reflectivity field (MAX_Z_3D), reflectivity at constant altitude - 2 km above sea level (CAPPI 2km) and reflectivity at constant altitude corrected by vertical reflectivity profiles in invisible regions (low altitudes far from radar – CAPPI 2km COR), (Šálek at al., 2004 and 2006). Radar products are visualized in 1km horizontal resolution in the web environment by JSPrecipView application (Fig. 4). Basin average, total and maximum for individual catchments are calculated for potential use in hydrological models.

Automatic Weather Interpretation (AWI) method is used to compare real measure data to numerical model output. Nowcasting up to 90 minutes is done for maximum radar reflectivity using wind field calculation. There are two methods of wind field computation used operationally. The first uses Numerical Weather Prediction Limited Area Model (NWP LAM) ALADIN 700hPa geopotential forecast interpolated into the radar image size and resolution and then recalculates motion field using the geostrophical approximation. COTREC method is based on comparing two consecutive radar images using mean absolute difference as a similarity criterion. For time extrapolation of maximum reflectivity field the method of backward trajectories is used, where wind field is constant during extrapolating

______BALWOIS 2008 – Ohrid, Republic of Macedonia – 27, 31 May 2008 4/7 time. The growth/decay factor of radar echo is not applied (Novák, 2007). Example of nowcasting output is presented in Fig. 5.

a) b)

c) d)

Figure 4. Radar products from JSPrecipView: a) original radar estimate of precipitation, b) radar estimate adjusted by average (spatial and time) coefficient of ratio radar–rain gauge, c) real-time rain gauge measurements, d) merging of radar precipitation estimates (adjusted) with real-time rain gauge measurements.

Figure 5. Example of CHMI operational nowcasting products (COTREC method).

Meteorological forecasting is based on the numerical weather prediction outputs. Obviously regional deterministic model outputs are used for short range forecasts, global models and ensemble products are used for medium range forecasts. CHMI forecasting offices use model outputs from different centres. For making short range forecasts and warnings up to 72 hours products from Aladin - CZ,

______BALWOIS 2008 – Ohrid, Republic of Macedonia – 27, 31 May 2008 5/7 Cosmo LM – DWD (Deutscher Wetterdienst) and ECMWF (European Centre for Medium Range Weather Forecasts) are processed and visualized. Forecasts and warnings up to 5 days are prepared using data from ECMWF, NCEP (Washington) and DWD meteorological centres.

Hydrological forecasting in the CHMI uses two different forecasting systems (models). AquaLog system used for Elbe river basin is based on the procedures of National Weather Service River Forecasting System (NWSRFS) used in the United States. HYDROG system has been implemented for Morava and Odra river basin on the east of the Czech Republic. HYDROG was developed in the Czech Republic using St.Venants equations.

Recently a number of probabilistic (ensemble based) outputs of numerical models were developed. Despite the disadvantage of mostly quite rough grid resolution (ECMWF provides main and control run in 27 km grid and 50 ensembles runs with even worse resolution) those information could be very beneficial for forecasters. As an example probability of precipitation over the threshold (Fig. 6a) or extreme forecast index (Fig. 6b) is often taken into account during the warning and forecasting in CHMI. Probabilistic multimodel products of PEPS (Poormens Ensemble Prediction System) are also used.

a) b)

Figure 6. Examples of ensemble output: a) probability of precipitation > 10 mm/24h. b) extreme forecast index for 24 hours cumulate precipitation

Conclusion The purpose of this paper is to inform and demonstrate how the warning system of CHMI is organized and how it works. CHMI as National Meteorological and Hydrological Service focuses not only in organization of warning service, but also on its realization in practice. Not only the forecast of dangerous weather must be keep in mind but also the whole link of its distribution and use to minimize the impact of dangerous weather on community and environment. CHMI as an actively member of Integrated Rescue System involves its forecasting offices in crisis management education to ensure that users get full benefit of reliable forecast and warnings.

The main goal of warning philosophy of CHMI is common and very closely cooperation between hydrological and meteorological forecasters. They work under one “umbrella” in one office and therefore cloud benefit from direct access to any necessary data, forecasts or some additional information shared in one team.

Warning issuing is the decision process demanding for suitable data and tools (software). Data (measured or forecasted) has to be quality checked, post-processed, usefully visualized and further evaluated. For timely reaction in warning process it is necessary to develop “watching dog” system, for preventive action for example in case of convective episodes (flash-floods, hails, wind gusts…) and

______BALWOIS 2008 – Ohrid, Republic of Macedonia – 27, 31 May 2008 6/7 some nowcasting methods based on radar data. Uncertainties in forecasting process could be partly solved using ensemble outputs as probability maps or graphs.

Overview given in this paper could not go too much in to detail in many aspects of CHMI forecasting and warning service organization and practice. However this paper could hopefully contribute to discussion on importance of efficient warning service as a part of crisis management.

References Davidson J., Wong M.C. (2005). Guidelines on integrating severe weather warnings into disaster risk management. PWS-13 WMO/TD-No. 1292.

Davidson J., Lam H., Lam Cy., Wass S., Dupuy C., Chavaux F. (2003). Guidelines on cross-border exchange of warnings. PWS-9 WMO/TD-No. 1179.

Šálek M., Novák P., and Seo. D.J. (2004). Operational application of combined radar and raingauges precipitation estimation at the CHMI. Proceedings of ERAD 2004, 16-20.

Šálek M. Březková L. Novák P. (2006). The use of radar in hydrological modeling in the Czech Republic -- case studies of flash floods. Natural Hazards and Earth System Sciences, 6, s. 229-236.

Novák P. (2007). The Czech Hydrometeorological Institute’s Severe Storm Nowcasting System, Atmos. Research, 83, 450–457.

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