Amateur radio needs great tools like this - William Hepburn's Tropospheric Ducting Forecast
I had never heard of it until I read about it on Tim Kirby G4VXE's blog but it is useful and in a simple to understand format. Tim says...
About a week or so, I got an e-mail from Matty, MD0MAN drawing my attention to some propagation forecasting websites. One that I hadn't come across before, though somewhere at the back of my mind, I think I've heard it mentioned, is William Hepburn's Tropospheric Ducting Forecast site. The site allows you to select the area of the globe that you're in - so in my case, I selected the North West Europe page but if you're in North America, this is your map
So many thanks to both Tim and Matty for drawing our attention to it. There is more to explore at http://www.dxinfocentre.com/index.html so thanks also to William for putting it all on the web.