From 10 days to 3 weeks! We are now testing a new 21-day weather forecast at Beta-Yr!
Yr currently has a weather forecast for 10 days ahead, but now we are extending the forecast period to 21 days. The weather forecast is under development, and is not quite finished yet, but is available at beta.yr.no (under the "21-day forecast" tab). Now in the test phase, we want to collect feedback and experiences from you users. The button just below the weather forecast can be used to criticise or praise us (please note that the feedback form is in Norwegian). A weather forecast so far into the future is more uncertain than a weather forecast for the next few days. Therefore, the warning is displayed in a different way than the normal weather forecast. We have divided the forecast into three rolling seven-day blocks, and the uncertainty in the warning means that the most important thing is to give an indication as to which direction the warning is moving further forward. You are welcome to test it out then!
Where can you find the new weather forecast?
The new 21-day forecast is linked to a weather forecast for a location, and not in map format. This means that if you search for a place located within the blue square in the figure on the right (covering parts of the Nordic region), you will get a 21-day warning for this place. The weather forecast is located under the "21-day forecast" tab.
Content in the forecast
The first 10 days of the 21-day forecast will correspond to the first 10 days of the normal weather forecast that is now seen on Yr. After the first 10 days and up to 21 days, data sets for weekly values from the ECMWF are used. From day 10 to day 14, the weather forecast is updated twice a day, and from day 15 to 21, it is updated once a day. There is a lot of probability calculation and ensemble forecasts behind these data, and up to 100 possible weather forecasts are collected in these long-term data. Various values are then calculated, such as the expected minimum and maximum temperature, but also the extremes such as the coldest and warmest possible, thus showing the uncertainty in the forecast. For temperature, these extremes make up the possible maximum temperature and the possible minimum temperature. For precipitation, expected and possible precipitation is shown in a table. There is also an information card showing which days of the week it is most likely to rain. At times when the weather forecast is updated with new forecasts, differences may appear for short periods in the new 21-day forecast and the usual forecast at Yr.
Figure text: The 21-day forecast on beta.yr. Top: Tables with expected precipitation, highest and lowest temperature, and probability of frost, broken down week by week, three weeks ahead. In the middle: Graph with the probability of little (blue) and much (purple) precipitation, given day by day three weeks into the future. Bottom: Graph with expected and possible temperature, given day by day three weeks into the future.
Can this forecast be trusted?
In general, one should have a higher expectation of accuracy for a short-term forecast than a long-term forecast, and the uncertainty becomes greater the further into the forecast period one arrives. These long-term forecasts will primarily tell something about the expected development and trend in the weather three weeks into the future. Therefore, both the level of detail and the time resolution in the weather forecast change depending on how far into the forecast period you get. On the next few days in the regular weather forecast, for example, you will be told at what time you can expect precipitation, while in week three, instead, it is stated how likely it is that precipitation will occur during a given day. Correspondingly, the time resolution also changes the further into the warning period you arrive. In the first few days you can see weather farecasts every hour, after a few days you will only get forecasts every six hours, and in the last half of the period you will only get forecasts for one day at a time. This way, the uncertainty in the forecast is taken into account. For industries that have to adapt operations to the weather conditions, such as for food producers or ship traffic in challenging areas, the trends in the weather development are important information. Other industries that can benefit from weather forecasts for several weeks ahead are, for example, the power and insurance industries. Even if the uncertainty becomes greater, verification results nevertheless show that it is possible to say something about the weather three weeks ahead at the level of detail we have chosen to display.
Give us feedback
The 21-day weather forecast is under development, and we would therefore very much like to hear about your experiences with the forecast. What do you think about this? Are there parts of this forecast that were helpful to you, and did you use the forecast to make any decisions? On Beta-Yr you will find the opportunity to give your feedback (please note that the feedback form is in Norwegian). When we have enough experience with this test version of the 21-day forecast, we will develop it further and it will also appear on the regular Yr page.
In collaboration with Climate Futures
The development of the forecast is a collaboration between NRK, the Meteorological Institute (MET) and Climate Futures. Climate Futures is a Center for Research-Driven Innovation (SFI) that develops climate forecasting from 10 days to 10 years ahead for managing climate risks in weather- and climate-exposed sectors, and MET is one of the collaboration partners. One of the aims of Climate Futures is to make society as well equipped as possible to be prepared for, and be able to cope with, more extreme weather events and phenomena. An example of the potential usefulness of such a warning is that players in agriculture can anticipate and prepare for prolonged drought in the summer. The weather data in the new long-term forecast is obtained from the meteorological center in Reading, ECMWF.