Strange weather phenomena occur around the Bella Coola airport with the vanilla default weather system too, I have choosen this airport to do some turbine testing after the Fenix update last weekend 
Very snowy outside for 19°C! (I don´t know how much medieval-Fahrenheit 19° Celsius are, but I start to sweat during such temperatures *ggg no snow can survive longer than an hour outside during this heat.)
Snow coverage in combination with temperature should get a closer look in the weather system. When daytime temperatures are over 10-12°C there should be no snow coverage in this area.