The Integrated RMI Alert system (INDRA)

G. Smet, J. Van den Bergh, M. Reyniers, D. Poelman, D. Degrauwe,

A. Deckmyn, R. Hamdi, P. Termonia, L. Delobbe.

Royal Meteorological Institute of Belgium.

13th EMS Annual Meeting & 11th European Conference on Applications of Meteorology (ECAM), 09-13 September, 2013, Reading, United Kingdom.

INTRODUCTION

INDRA is a system is under development at the Royal Meteorological Institute of Belgium (RMI), to improve our capability to issue alerts and warnings to the public for extreme events, in particular heavy precipitation, flooding and thunderstorms. The relevance of this was confirmed in 2011 by the famous Pukkelpop thunderstorm, where the RMI carried out its task according the current meteorological state of the art, but which also pointed out potential for developing new applications to further improve the warnings for such cases.

The main aim of INDRA is to integrate and provide a common platform for RMI products that involve warnings for extreme precipitation (rain and snow), high waters and thunderstorms. This includes visualization of various forecasts, and their continuous verification and validation. Different systems will contribute towards the early warning system.

The INDRA system uses probabilistic forecasts and predetermined thresholds to issue alerts for extreme quantities of rain and snow, at different lead times. Hydrological forecasts, giving early warnings for high waters, are also included on the platform. These are aimed specifically at the regional authorities responsible for water management.

We illustrate the current version of the INDRA system using hindcasts for the Pukkelpop thunderstorm of 2011.

HYDROLOGICAL ENSEMBLE PREDICTION SYSTEM

SCHEME provides the initial conditions in each grid cell at day D. It is then run in forecast mode, forced with input data from the ECMWF Ensemble Prediction System (EPS) forecast. Both precipitation and other meteorological data are taken from the EPS forecast. The main use of the forecasts is to issue pre-alerts for high waters at medium to long range lead times, aimed at Belgian regional authorities. A hindcast and verification of the forecasting system was performed by Van den Bergh and Roulin, 2010.

GLAMEPS

GLAMEPS is a pan-European, multi-model, local area model ensemble prediction system for the short-range (first 2 days). At the time of the Pukkelpop thunderstorm, GLAMEPS_v0 (Smet et al., 2012) was pre-operational. It consisted of 52 members (13 ALADIN members, 26 HIRLAM members, using 2 different model versions, and 13 ECMWF members) delivering forecasts 42h ahead, twice a day. The ALADIN and HIRLAM members are coupled to the first 13 members of the global EPS of ECMWF, and supplemented with the same 13 ECMWF-EPS members.

INDRA COMPONENTS● ECMWF Ensemble Prediction System (EPS).

● Grand Limited Area Model Ensemble Prediction System (GLAMEPS).

● INCA-BE nowcasting system.

● BElgium Lightning Location System (BELLS).

● RMI hydrological ensemble prediction system.

Fig. 2. Meuse and Scheldt basins, with the catchments of the Meuse basin included in the current operational procedure. Also shown are the EPS N320 reduced gaussian grid points.

REFERENCES• Van den Bergh J., Roulin E. (2010), Hydrological ensemble prediction for the Meuse and Scheldt basins, Atm. Sci. Lett., 11:64-71.

• Smet G., Termonia P., Deckmyn A. (2012), Added economic value of limited area multi-EPS weather forecasting applications, Tellus A, 64, 18901.

• Reyniers M., Delobbe L. (2012), The nowcasting system INCA-BE in Belgium and its performance in different synoptic situations, ERAD2012, Toulouse, France.

• Poelman D.R., Schulz W., Vergeiner C. (2013), Performance Characteristics of Distinct Lightning Detection Networks Covering Belgium, J. Atmos. Oceanic Technol., 30:942–951.

BELLS

RMI has been operating a total lightning location system (BELLS) since 1992, detecting cloud-to-ground as well as cloud-to-cloud lightning discharges. A combination of a direction finding and a time-of-arrival technique is used to process the data into valid locations (Poelman et al., 2013).

PUKKELPOP 2011

On the 18th of August 2011, around 16h15 UTC (18h15 local time) a summer thunderstorm hit the festival site of Pukkelpop, a popular annual music festival near the city of Hasselt, Belgium. Around 60.000 people were present...

The thunderstorm had an unusually big impact: 5 deaths and approximately 140 wounded.

Probably due to downbursts, i.e. strong downdrafts which induce outbursts of damaging wind near the surface, since no signs of a tornado (rotation) were seen in the damage survey. They occurred on hectometer scales, so too small to simulate with our current models.

INCA-BE

INCA is a nowcasting system developed at the meteorological service of Austria (ZAMG). The system was adapted for a domain around Belgium and for our local observational data flow. INCA-BE (Reyniers and Delobbe, 2012) became (pre-) operational during Spring 2012. A post-analysis of the Pukkelpop storm was performed, showing the 1h forecast was quite accurate, except for a time shift of approximately 10 minutes.

CONCLUSIONS/OUTLOOK

- After the Pukkelpop thunderstorm, the RMI decided to offer a custom product for organisers of outdoor events: the Outdoor Event Forecast. The biggest outdoor mass events in Belgium were integrated in the INCA-BE system.

- The thunderstorm was forecast rather well, according to the current state of the art, but had an unusually big (and arguably unforeseeable) impact. However, to predict downbursts probably much higher resolutions are necessary.

- INDRA will be further developed: EPS based probability of thunderstorm maps, implementation of an automated alert system consistent over all time scales, verification,...

Fig. 1. Visual satellite image of 18 August 2011, 15h45 UTC. Overshooting top visible over the province Limburg, Belgium.

Fig. 3. GLAMEPS-o-grams for T2m, S10m and AccPcp3h (at the Pukkelpop festival site).

Fig. 5. Cloud to ground lightning detected by BELLS on 20110818 between 16h UTC and 17h UTC, coloured per 10 minutes (light yellow:16h00 UTC - 16h10 UTC, dark red:16h50 UTC - 17h00 UTC).

Fig. 4. INCA-BE analysis at the (estimated) time the thunderstorm passed Pukkelpop. The festival site is marked with a red square.