For years now I've been using Metcheck as one of my go-to sources for weather forecasts.
Their storm forecast used to be one of my favourite features, but it's a long time since I saw anything believable in their LI column, so I recently got around to making my own.
I'm not producing my own forecasts, of course. The data is provided by the National Oceanic and Atmospheric Administration in the USA, who use clever mathematics and powerful supercomputers to produce weather forecasts for every point on the planet, and then make them freely available on the Internet for anyone to download. Thank you NOAA!
Perhaps I'll add more over time. There's a lot more data available.