Check-out the following link, it offers a lot of interesting articles to read. If you scroll all the way down to the bottom you'll find an article about weather which is particularly interesting to pilots at the early stage (PPL) called "Weather Wise" I highly recommend it.
Safety Advisors - AOPA
You can also go to Youtube and search for "thunderstorm hazards / avoidance aviation" you'll find some interesting videos.
Have fun and fly safe, always
