@WeatherMan10 You are absolutely right. At a given location, a 15-day forecast, regardless of the model, has no value at such a time frame. Beyond 5 to 7 days, a local weather forecast will have less and less chance of coming true. So why does Windy present these detailed 15-day forecasts? When these forecasts on Windy were only 10 days, many users asked for them to be extended to 15 days ! On the other hand, as you said, a 15-day forecast on a large scale (synoptic) allows you to get an idea of ​​the trend for the next 2 weeks.