The only problem you can usually get from snow is when it melts, the bulbs get heaved up and dry out since the freeze thaw cycle caused bulbs that are planted too shallow to come upwards, but onions and garlic should be hardy enough to take anything in zone 8b so I don't think there's any issues with that. If they are heaved up, just press them back into the soil and they will be fine.

Snow actually serves as an insulator for garden plants.

Here is a link that might be useful: Here's some pictures of how I protect my garlic