Yr provides a 21-day forecast
Now you can get a weather forecast for three weeks on yr.no. This is a significant leap from the ten days we have been forecasting the weather for until now.
The 21-day forecast, as the name suggests, shows the weather development for the next 21 days. The weather forecasts indicate temperature trends and chances of precipitation day by day, along with a summary box providing an overview for the three 7 day periods. These long-term forecasts primarily convey information about probabilities and trends, and they will not, for example, specify the exact time of day when it will start raining in 2-3 weeks. You can find the forecast under the tab "21-day forecast" on the website yr.no.
— The time has come
The forecasting horizon is not often extended, and there has been a long journey to the current 21-day forecast. In the early 1900s, weather forecasts in Norway were limited to the current day, with a hint of the weather for the next day. Over the past 100 years, weather forecasting has undergone significant development both in Norway and the rest of the world. In the early 1970s, MET started with a 5-day forecast on NRK TV, and by the late 1990s, we began forecasting 10 days ahead. For more than 16 years, Yr has been providing weather forecasts to the public. The development has been research-driven and user-oriented.
— Weather forecasts have become increasingly detailed and more frequently updated. This has been possible because we have been at the forefront methodically and technologically, including how we use weather observations. Our research has now taken this further and extended the long-term forecast to 21 days, says Jørn Kristiansen, director of the Center for the Development of the Forecasting Service at MET.
The new 21-day forecast has long been desired by various user groups, says Bård Fjukstad, the forecasting director at the Meteorological Institute.
— With the 21-day forecast, we are expanding our services in a good and useful way, says Fjukstad.
Long process based on feedback
The philosophy for new and improved services on Yr is that a weather forecast is not complete until it is understood and used, and that it is useful and has value for the user. Ingrid Støver Jensen is the product development manager and head of Yr at NRK, and she explains that the process of developing new services on Yr is often extensive.
– The journey to a new product has gone from ideas and discussions, through several rounds of research and development, design, concept development, user testing, and beta versions before launch. The work on the 21-day forecast has actually been ongoing for three years, says Støver Jensen.
Key questions the Yr team had from the start were: How can we design the forecast to provide a better understanding of uncertainty further into the future? And will the forecast still be useful when we emphasize probability information?
– We knew that the forecast would be especially relevant for people making decisions today for something dependent on the weather in the future. For example, someone planning something in the future depending on the weather but with the option to change plans later. An example is a farmer wondering when it's wise to sow, fertilize, or harvest, explains Ingrid Støver Jensen.
The Yr team has worked closely with the target audience, including a panel consisting of farmers, people from the maritime industry, and the insurance industry.
The new 21-day forecast is originally based on three different weather forecasting models, all updating at different intervals and with varying geographic resolution. Significant effort has been made to make the new forecast a seamless weather forecast, which at all times also aligns with the original 10-day forecast. Similar to the regular forecast on Yr, the 21-day forecast is also calibrated, among other things, using data obtained from private weather stations.
– The 21-day forecast was posted on beta.yr.no just before the summer of 2023, and we received hundreds of feedback from users. Based on these, some changes and adjustments were made to the forecast, both in terms of data and in concept and design, before it was launched. Users like Gartnerhallen have also actively tested the product, continues Støver Jensen.
It is still possible that adjustments will be made even after the launch based on new feedback. At the bottom of the forecast page, there is a link where users can provide feedback on the new product. On the help pages of Yr, you can find some more details about the new forecast, which is available on Yr.no.
In collaboration with Climate Futures
The weather data in the new long-term forecast is sourced from the European Centre for Medium-Range Weather Forecasts (ECMWF). The development of the new forecast is part of the work in Climate Futures, where MET is one of the partners. NRK is also involved in developing the new forecasts on Yr. Yr is a collaboration between NRK and MET.
Climate Futures is a Centre for Research-Driven Innovation (SFI), funded by the Norwegian Research Council, which develops climate forecasting from 10 days to 10 years ahead for managing climate risks in weather- and climate-exposed sectors. Øyvind Paasche is the director of the center and emphasizes that one of the goals of Climate Futures is to make society as well-prepared as possible to handle more extreme weather events and phenomena.
A longer forecasting horizon, such as 21 days, can be useful for industries that need to adapt operations according to weather conditions. An example could be actors in agriculture who need to anticipate and prepare for prolonged drought in the summer. Other industries that benefit from weather forecasts several weeks ahead include, for example, the energy and insurance industries.
Chief researcher for Climate Futures, Erik Kolstad, has followed the process of developing the new forecast.
– Within long-term forecasting, we experience the greatest need for more services within the time horizon that Yr will now cover. The farmers we work with are very interested in what happens more than ten days ahead and are likely to welcome the new service with open arms. We are very pleased that Climate Futures has had the opportunity to contribute to the development of the new forecasts, as the societal benefits are obvious, says Kolstad.
Similar to much of the data behind Yr, the data for the new 21-day forecast is open and can be used by others to create services. The data is available at api.met.no.
For meteorological questions about the service or questions about the weather:
Phone 480 69 615
Yr-related questions: Product Development Manager and Head of Yr at NRK, Ingrid Støver Jensen
Phone 402 13 725