Lore Friendly Ice Durge

Hi all!

Looking to go full Ice Sorcerer for my next Durge playthrough, but I want to be as lore-accurate as possible. Obviously, I'll be playing White Dragonborn Sorcerer, but I'm feeling a bit stuck on subclass.

Storm Sorcery is the 'default' Durge subclass, so ideally that'd be my pick, but it doesn't seem to be able to hold a candle to Draconic Bloodline in terms of effective ice output. Are there any ice-focused builds for Storm Sorcery, or am I going to be stuck mainly focusing on lightning?

On the other hand, White Draconic Bloodline is pretty well documented as the pick for ice builds, but I'm having a hard time justifying running with a bloodline subclass for a character who was built and not born. Has anyone found a good lore-friendly way of explaining this?

TL;DR: I'm looking for an ice-focused Storm Sorcery build that can stand up next to Draconic Bloodline... or, alternatively, a way to justify going 'bloodline' for a character who canonically wouldn't have one.

I'd ideally prefer to go straight 1-12 Sorcerer without multiclassing, and will be playing on Tactician, if that counts for anything.