You cannot cast avalanche in much of the Tahril mountains. Not sure if that goes for all rooms, as I didn't go into all of them, but a whole lot that you should be able to avalance...you can't.

Example:
People near you:
(PK) Me The western mountain face

<100%hp 100%m 16%mv 304tnl> c ava
There are no mountains nearby from which you could call an avalanche.

<100%hp 96%m 16%mv 304tnl> l
The western mountain face
The wind whips mercilessly across the western face of the mountain. Far
below you can see the red and tan sands of the Desert swirling around. The
peak of the mountain rises high above you. A few dark spots on the
mountain face lead you to believe there may be cave entrances near.

You're flying in the air...not standing on the mountain.