That avalanche gal of Terri's pretty much looks, for all intents and purposes, like a snow with a plain belly. She is on the far end of the spectrum where the side pattern and head pattern aren't exhibiting much diffusion at all.
Below are a few pics of clutchmates who are an avalanche and a snow. This avalanche does show some diffusion, but I'd put her pattern at the midway point between Terri's gal who exhibits very little dorsal or side pattern and the classic diffusion pattern of having little to no side pattern and a skull or plain head. I think, just like with pewters and bloods, that avalanches will have a huge variation in pattern expression depending on the lines.
Head shots: Near skull on the avalanche, normal pattern on the snow
Notice the "peppering" or holes in the white patterning of the head. This is a consistent finding in my diffuseds and diffusion hets.
Dorsal, side, oblique, and belly shots of both snow and avalanche:
You can see "holes" in the background of the avalanche, just like the granites out of the clutch. The side pattern is fractured, but not completely gone. The bellies are obvious. The avalanche is also much less pink (not that that has anything to do with the trait) than its sister.