Ok, to update, there is a trick to the Snowball meteor spawns. You DO need to be in the region center, but you have to enter on foot!
In a way this is pretty helpful here as people entering the world won’t be setting them off just by visiting or opening portals. However, exiting and reentering the same region didn’t work for me - had to hike to the next. LUCKILY however, I’ve got so many of these up that I doubt there are any you can’t see the nearest ones from on the compass. 
Any settlement/portal markers are region centers. Choose a portal and start walking - it is easy terrain! 
Thanks @Rydralain for figuring this out! 