During my service in Emergency Management Operations, I needed to gain certification as a weather spotter. I used this Advanced Spotters Field Guide to help me.
There is a lot of information found in this National Weather Service document to help outdoorsmen as well as preppers.
Advanced Spotters Field Guide teaches you how to understand weather patterns to help predict the weather.
A free PDF will not make you a weatherman, but within limits, you can understand weather patterns and know what is going onADVANCED_SPOTTERS FIELD GUIDE
There really is not a lot to say, the PDF above comes from the National Weather Service and is the textbook to their advanced weather spotter class.