The six vertex model can be reformulated as a theory of random
stepped surfaces called height functions. In the thermodynamic limit, the
random height function of the model typically converge to a deterministic
limit shape. We study the limit shapes of the six vertex model with
stochastic weights, for which the six vertex model can be viewed as a
Markov process. We show that the limit shapes are determined by a
conservation law type PDE, that can be solved by the method of
characteristics.