"Va a haber mucha nieve allá."
Translation:There is going to be a lot of snow there.
Note that "nieve" is the noun "snow" and "nevar" is the verb "to snow", so the translation for what you wrote down would be "Va a nevar mucho allá".
There is a slight difference in meaning. For example, in response to "I'm going to Chamonix tomorrow":
- "Va a haber mucho nieve" indicates that there's already a lot of snow there, whether or not more is expected.
- "Va a nevar mucho" means that a lot of snow is going to fall while the person is there.
Now it won't accept "there is going to be much snow there". The test page had "There is going to be lots of snow there.", which is different than translation given on this page (which has happened a lot, lately; or should I say much, lately). So it seems Duo is having trouble figuring out the "correct" answer!