Purity: Use of Snow or Ice for Purification

Practical Laws of Islam as per the teachings of Ayatullah Sistani

Ruling 677:

If someone does not have water but does have snow or ice, in the event that it is possible, he must melt it and perform wuḍūʾ or ghusl with it; and if it is not possible and he does not have anything with which tayammum can be validly performed, it is necessary for him to make up the prayer after its time. Furthermore, it is better that with the snow or ice he wet those parts of the body on which wuḍūʾ or ghusl is performed, and in the case of wuḍūʾ, he should wipe his head and feet with the wetness on his hands. If this is not possible, he should perform tayammum with snow or ice and perform the prayer within its time. In both cases, it is necessary for him to make up the prayer afterwards.

-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)