Push notifications and text alerts would be great. As a rope access wind turbine technician I use Windy extensively, but it's a bit of a pain to have to check my email for alerts or setup some kind of email rule that would run and send me a different notification. Windy is one of the only weather apps I use anymore and the only reason I use any others is because they offer more user-friendly notifications.
Also, lightning alerts are a bit lacking in Windy. I love the interface for tracking storms and seeing recent strikes, but there isn't a way to get notifications about them. It would be immensely helpful if we could set a customizable radius that would trigger lightning alerts at the given distance. For my job, we are on alert when lightning is within 50 miles and we call a stop work when lightning is within 30. Having this available as a push notification or text message would make Windy all the much more valuable.
PS I've been preaching the wonders of Windy to all my co-workers and everyone seems to love it except that the notifications aren't that intuitive. Keep up good work!