One of the best upgrades to your iPad is a datalink weather receiver like a Stratus, Sentry or GDL. These portable avionics sit on your dash or suction cup to a side window and receive either subscription-free ADS-B weather from ground stations or SiriusXM satellite weather that requires a monthly subscription. Regardless of your receiver, there are some important rules to follow. In this video tip, you’ll learn how to evaluate radar images to determine if they are dangerous thunderstorms or just rain. There’s more to it than just green, yellow and red colors.