Within the context of the cooperation between EUMETSAT and ESSL on user preparation for the MTG data, an experimental visualization of Lightning Imager (LI) data was introduced to the ESSL Weather Displayer. Its preliminary name is “Geometry and density” and it connects all the detected LI groups (connected pixel detections at one acquisition frame of 1 ms) within one single LI flash (collected LI groups that are correlated in space and time within 330 ms) and can be taken as a proxy for the geometry of the flash as seen from space. Each flash is given a different colour. Such a flash geometry can cover large areas, something that has earlier been discovered by using the ISS-LIS and GOES-GLM instruments. In the ESSL Weather Displayer, the visualization combines this information with data on highly active convective cells. Those active cores are made visible via plotting the LI group density if surpassing 1 LI groups per km² within a 5 minute time frame (colour shading from black via magenta, red, orange and yellow to white). Possible applications of such a product may range from public outreach activities via identification of new active updrafts all the way to lightning safety at airports.

LI group density is also visualized in gridded form. In addition, the area size of flashes is plotted for each single flash (the size of red or yellow circles related to the flash area). This allows a forecaster to identify physical processes that are ongoing within a convective complex. Large flash areas are typical for flashes in the stratiform regions while a high number of small flashes can be indicative for a very intense updraft, as it is often seen with supercells in early LI data.

You can read the full newsletter here.

Figures: Screenshots from ESSL Weather Displayer for a geographic area of Albania and surroundings on 4 October 2024 at 09:00 UTC. Left: LI Group Area (red circles). Middle: LI Group Density. Right: LI Geometry and Density (geometry approximation of LI flashes and LI group density above 1 for identification of active convective cores). Data source: EUMETSAT. Visualization: ESSL.

Wiener Neustadt, Austria, 15.07.2024

Europe needs Twisters campaign

Researchers from all over Europe are organising high-density measurements of severe storms. Similar to the new film Twisters, the plan is for mobile storm chasing teams to collect essential weather data directly from storms.

This is planned to be ground-breaking. Severe weather researchers from 14 European countries want to work together to get to the bottom of severe thunderstorms so that they can provide better warnings in future. To this aim, they are currently planning the largest European measurement campaign on severe thunderstorms to date. “We want to use the latest technologies, such as weather drones. To do this, it is extremely important that mobile measurement teams get very close to the storms. This is the only way to gather the crucial information,” says Alois Holzer, initiator of the European “TIM” measurement campaign to start in 2026.

As can be seen in the new movie Twisters, the European research teams will also be tackling the storms with the newest generation of weather sensors. “In contrast to some scenes in the entertainment film Twisters, however, the highest safety standards apply in our research campaign, and we have also made a joint commitment to responsible behaviour with regard to the environment and the local population,” emphasises Alois Holzer, Director of Operations of the European Severe Storms Laboratory ESSL in Wiener Neustadt.

While the basic scientific structure is to be financed through traditional research funding, the project is still looking for major donors for the individual mobile measurement teams. Alois Holzer says with a twinkle in his eye: “We hope that the kind of support from major donors possible in North America can also be achieved in Europe. We are also in dialogue with various public authorities.”

The urgency of being able to better understand and predict severe weather, and thus to strengthen civil defence, is certainly given, as the frequent severe weather events show. The measurement campaign will focus on hailstorms, flash flood events, dangerous squalls and tornadoes. In the past year alone, severe thunderstorms have caused 524 fatalities in Europe, as reported by the ESSL.

The ESSL is an independent, non-profit research institute based in Wiener Neustadt in Lower Austria. It also operates the European Severe Weather Database (ESWD) and is a European leader in the training of meteorologists in the field of severe weather warnings. A year ago, the ESSL established the International Fujita Scale (IF-Scale) as a new standard for categorising tornado damage.

This press release is under embargo for re-publishing until: Wednesday, 17 July 2024, 00:00 UTC

LINKS:

European Severe Storms Laboratory (ESSL):         www.essl.org
TIM Field Campaign:                                                  www.tim-campaign.eu

LIVE EXPERT TALK:

The TWISTERS expert talk will take place on Tuesday, 16 July 2024:

Attendance:

Less than a week after setting a new European record, a hailstone 19 cm in diameter was found in Azzano Decimo, Italy.

The previous record of 16cm in Carmignano di Brenta from 19 July lasted for only five days. On 24 July 2023 at about 11 PM in the evening, giant hail hit the town of Azzano Decimo, where the record breaking hailstone was found. After a thourough examination of the reports and photos, the specialists of the European Severe Weather Database (ESWD) came to the conclusion, that the diamter of this hailstone can be confirmed as 19 cm.

The new hailstone comes very close to the world record of a hailstone from 23 July 2010 in Vivian, South Dakota, with a diameter of 8 inches (20.3 cm).

The high frequence of hail in Northern Italy is consistent with research results of the European Severe Storms Laboratory (ESSL), showing, that this region has experienced the largest increase in the frequency of large hail, compared to other European regions in the past decades.

At the end, ESSL want to thank its local partners, as PreTemp in Italy, and the reporters of hail to their great collaboration and contributions to the European Severe Weather Database (ESWD)!

On 19 July, severe hailstorms affected large parts of Southern Europe. According to the experts of the European Severe Storms Laboratory (ESSL) so-called “giant hail” (hailstones with a diameter of more than 10 cm) was reported 24 times; 2 times in Croatia and 22 times in Italy!

In Croatia, the largest hailstone was found in Ribnik, estimated to be 13 cm in diameter. In Italy, the largest hailstone fell in Carmignano di Brenta. The specialists of the European Severe Weather Database (ESWD) estimate the size of this hailstone to be 16 cm in diameter, based on photos.

“According to our information, this would be the largest recorded hailstone in Europe”, says Thilo Kühne, Quality Control Manager of the European Severe Weather Database. “The previous record was a 15 cm hailstone from 20 June 2016 in Sânandrei, Romania”.

Besides enormous economic damage, the hail caused 109 injuries on that day alone, according to the European Severe Weather Database.

ESSL obtaining its data from a large European network of weather entusthiasts and cooperating weather services. The Italian cases, including the new record braking hailstone, were reported by PreTemp, which collaborates closely with ESSL.

The experts of ESSL and the European Severe Weather Database urge all people sending photos to the weather services or our data base, or posting hail pictures on social media, to use a ruler, coin or other reference objects next to the hailstones when making a picture. This makes it easier to estimate the exact size of hailstones.

ESSL was asked by the City of Wiener Neustadt to support a major civil defense exercise for the city and surrounding districts. On July 5th, shortly before the start of the exercise, ESSL Director of Operations Alois Holzer gave a lecture on tornado basics as a prelude for the management team of around 40 officials. The tornado scenario of the exercise concerns urban areas.

Already 10 years ago, ESSL provided the tornado scenario for a similar civil defense exercise. The recent talk gave the participating entities insight into the impacts of violent tornadoes. Part of the presentation was the case of 24 June 2021 over Czechia, when 6 persons died and hundreds were injured in an F4 tornado. Even more people were killed in the historical tornado event of the year 1916, when 34 persons died in another F4 tornado that struck the northern neighborhoods of Wiener Neustadt.

In June 2023, Méteo-France has become a member of the European Severe Storms Laboratory. This means that they have joined the present 25 Institutional Members of ESSL: public or non-profit organizations in Europe active in the realm of weather and climate forecasting or related fields. The ESSL Team extends a warm welcome to Météo-France, which will now have full access to the European Severe Weather Database to support its activities. In addition, full ESSL members have a vote in ESSL’s General Assembly and benefit from reduced participation rates in ESSL activities. ESSL is looking forward to the cooperation with Météo-France.

On the occasion of the first EUMETSAT-ESSL Testbed in 2023, the mayor of the city of Wiener Neustadt, Klaus Schneeberger, and the head of the governmental science department of the Federal State of Lower Austria, Martina Höllbacher, paid a visit to ESSL this week.

ESSL staff informed the officials on the anticipated advances in connection with the new satellite generation (EUMETSAT MTG). Our guests have been impressed by the variety of impactful activities the small ESSL team has undertaken over the past years, as documented by scientific posters and by the growing list of events, ranging from testbeds and seminars to expert workshops.

The official visit took place on 8 June 2023. The next day, a science journalist from the Austrian Broadcasting Corporation (ORF) visited our ESSL Research and Training Centre to interview participants and prepare a report on the EUMETSAT-ESSL Testbed and its importance for operational meteorologists in Europe. This week, participants from 15 different countries are taking part, from Ireland to Turkey, and from Portugal to Finland.

ESSL and collaborators drafted a document on the “International Fujita Scale” (IF-Scale). It defines a new method to rate tornado and wind damage and was presented at the European Conference on Severe Storms in Bucharest, Romania, earlier this month.

The document is open for commenting until 31 May 2023. ESSL plans to implement the new scale in the European Severe Weather Database by 1 July 2023.

More information on the IF-Scale draft you can find here.

The workshop is scheduled for autumn, from 16 to 18 October 2023, and takes the very broad view. Target audience are forecasters (“warners”) and heads of forecasters, researchers and practicioners related to warnings, civil protection authorities, and end users of warnings (especially from critical infrastructure).

The following topics will be covered:

1. The broad multidisciplinary view: risk ethics (philosophy, moral reasoning), human behaviour (psychology) and legal frameworks (just) in the context of the warning process
2. Limitations and new prospects for ingredients-based warning approaches: How should the risk matrix be defined? Can more life be brought to forecasting impacts beyond the marketing term?
3. Communication – dealing with uncertainty: Why is there so little progress in communicating the warning uncertainty, and how can this be improved?
4. Action advice and public education: from understanding to response and action. We are seeking for good practice examples.
5. General and tailored warnings: What are the necessary differences? And how can the gaps between warners, emergency managements and end users be best bridged?
6. From physical ingredients to impact warnings: Are impacts in high-end meteorological events easier to predict and stronger tied to the physical magnitude than in more frequent and modest events?
7. A critical moment in the meteorological sphere: transition from forecasting to nowcasting and the resulting potential sudden jump in probability of extremely rare events. Should there be a stronger focus on the warning means in the “last hour”? When in time and at which probability and intensity threshold should sirens and other “strongly interrupting and potentially also frightening” means of warning be used?
8. Cross-institutional and cross-border communication: What is needed to ensure the flow of relevant information in extremely time-critical and high workload situations?

A detailled invitation can be downloaded here (PDF).

The registration for the 11th European Conference on Severe Storms is open and normal registration fees apply until 7 April. Starting 8 April, late registration fees do apply.

Please register here for on-site participation or online streaming (remote presentations are not foreseen).

General information on the ECSS including the scientific and social programme can be found here.