The avalanche bulletin and a whole series of supporting products are published by the avalanche warning service, which, as part of the SLF, is always in a position to implement the latest research findings.
To ensure that users can rely on these bulletins, measurements as well as observations and assessments from the field are analysed and interpreted. The weather outlook is mainly determined with the aid of weather models. The avalanche forecast involves assessing avalanches' impact on the development of both the snowpack and the avalanche danger. This requires not only rules, an understanding of the relevant processes and a lot of experience, but also wide-ranging programs, for example to create visualisations of the measured values and to model the snowpack as well as for the creation and publication of the respective products.
There is a rota ensuring that three of the seven avalanche forecasters are on avalanche watch duty at all times. Between seasons and when not on duty, they draw up winter and weekly reports, handle the observer network and accidents, are involved in training, develop new products and perform a variety of research and project work.
A quick look at a day in the warning office shows how the avalanche bulletin for the next day is put together:
Assessing the avalanche danger is an ongoing process. Producing the next day's forecast already starts before midday the previous day with a detailed analysis of the data. This involves the avalanche forecasters analysing all the information available with programs developed specifically for this purpose. They focus on the factors that have a determining effect on avalanches forming and their likely development in the days ahead. A briefing takes place at 3 pm. At this meeting, the staff from the main shift present the results of their analysis, and then the various avalanche forecasters' assessments are compared and discussed. At the end of the briefing there will be clarity about the snow layering, the most likely weather conditions and, based on this, the expected avalanche situation, including danger levels, particularly affected locations and avalanche problems.
The avalanche forecasters then write up the bulletin and produce the hazard map. Before being sent out, everything is carefully read through and corrected again. At 5 pm every day, the products must be published, so just before this the radio station SRF 1 broadcasts a live interview with the main shift. In the meantime, a translation agency will have translated the German original of the "Snowpack and weather" text into French, Italian and English. The translations are checked by the avalanche forecasters and published by 6 pm at the latest.
The text of the avalanche bulletin concerning „Snowpack and weather“, which has already been written before the briefing by the forecaster on duty, is proofread and edited if necessary. The avalanche forecasters then compose the danger description for each individual danger region and produce the avalanche danger map. Before being sent out, everything is carefully read through and corrected again. At 5 pm every day, the products must be published, so just before this the radio station SRF 1 broadcasts a live interview with the main shift. In the meantime, a translation agency will have translated the German original of the "Snowpack and weather" text into French, Italian and English. The translations are checked by the avalanche forecasters and published by 6 pm at the latest.
At 5.30 am the next day, the staff from the main shift start working on the next analysis. The focus of their attention here is on unexpected developments during the night, information from observers that does not fit in with the existing picture, and changing weather forecasts that could call for a revision of the previous assessment. The relevant briefing is held at 7 am, and then the adjustments are made and checked. The automatic translation of the danger description means that final changes can be made until just a few minutes before the publication time of 8 am.
A lot more than expert avalanche knowledge and information about developments in terms of snow and the weather is needed to produce the avalanche bulletin twice a day. The SLF's Warning and Information Systems team develops for avalanche warning services tailor-made software solutions that are not available through commercial channels. These include data recording and analysis tools as well as editors required to produce the bulletin, and dispatch programs providing access to the bulletin from the internet and smartphones.
Analysis and visualisation
With around 180 IMIS stations, as well as other MeteoSwiss automated stations, 200 observers, snowpack models, meteorological forecasting models and weather reports, there is a huge volume of data which can only be handled appropriately if the values are processed and visualised properly. Global Information System (GIS) technology is used as a basis for the interactive spatial data visualisation. In this context both measurements and observations or assessments can be presented and statistical values can be calculate
The avalanche bulletin is produced using the bulletin editor specially developed for this purpose at the SLF.
This is a text editor used to compile a description of the snowpack and weather information as well as the outlook for the two days following the forecast period. Like all warning products, this part is also checked by a second avalanche forecaster and then immediately sent to the translation agency. This text is translated into Italian, French and English language by a translation agenc
For the danger assessment and the danger description, the avalanche forecasters assign a danger level with the click of a mouse to each of Switzerland's more then 120 warning regions and supplement these by inputting the areas particularly affected. Warning regions with a similar avalanche situation are grouped together as 'danger regions' depending on the conditions prevailing at the time. No assessment is made for largely snow-free warning regions.
Catalogue of standard phrases for automatic translation
The avalanche forecasters compile a specific danger description for each danger region. Especially in the mornings, the time frame between the arrival of the observations from the field and the publication time is too limited to produce a manual translation. In this light, a fully automatic translation system was developed at the SLF. It is based on a catalogue of predefined phrases which have already been translated into all the required languages and saved in the database. When producing the bulletin, the danger descriptions are not written freely but made up of these phrases, meaning that they are immediately available in all the relevant languages. To cover every possible situation, the individual phrases do not have a fixed structure. They consist of individual segments, which are selected from various predefined options. Paper on the catalogue of standard phrases: download as a .pdf file
When the danger assessment and the danger description have been finalised, the publishing application is used. This application reads the recorded information from the database, using this to compile and publish the various products. In total, up to 200 different products are compiled for each edition of the bulletin, with not only the interactive avalanche bulletin but also print versions and various special products.