If you are interested what happens in ice ages this might interest you

1. Of course, you'll recall that water expands when it freezes, so you could cool all the water on the planet to, say, -5 celsius. (You can't just go to 0 celsius, since the salt in seawater keeps it from freezing for a few more degrees.) Since water expands about 9% when it freezes, 1.3 billion cubic kilometers of water would yield 1.41 billion cubic kilometers of ice, or an extra 110 million cubic kilometers of ice. If you spread that ice evenly over the earth's 150 million square kilometers of land, it'd cover everything to a depth of about 730 meters. Of course, the ice would have no reason to spread evenly like that over uneven terrain, so it'd be more likely to fill in the lower-lying areas, while leaving tall hills and mountains sticking out. There's also one other catch - unless you were able to seriously violate the rules of physics, the surface of the ocean would freeze first, and once it froze to some not-so-great depth, further chilling the surface really wouldn't have much effect on the temperature of the water deeper in the ocean. It'd be like when a lake freezes in the winter - solid surface, but liquid underneath - and that would mean not having anywhere near as much ice to cover the land.
2. end partial quote from:
3. https://www.quora.com/Is-there-enough-water-in-the-ocean-to-cover-all-the-land-on-earth-If-so-how-many-feet-of-water-on-average-would-the-land-be-submerged-in

The most interesting point to me about all of this at this point is that it's true like when I go to Castle lake since I was in my 20s and ski across it in the winter across from Mt. Shasta at around 6000 feet in altitude the ice is usually 2 to 3 feet thick and often has snow on top of that too. I saw a man who had swept all the snow off the ice in a large section of the lake so he could ice skate on the lake this last winter but that seems like a whole lot of work to do that just to ice skate. But, to each his own.

But, I'm thinking that the oceans would make the east coast of the U.S. and the west Coasts relatively free of snow because oceans maintain their warmth like heat batteries now because of Global Warming whereas the lands easily loose their heat in winter when they are too far from the oceans.

So, an Ice age could begin from the Sierras and Cascades on the West Coast and completely cover the land of the U.S. and Canada from the Sierras and the Cascades to the Appalachian mountains on the east coast. But, likely the ice would only be between the Sierras and Cascades all the way to the appalachians and that would be it and they could come down like they came into Texas this winter too with Texas covered with ice in an ice age too where it could be ice from southern Texas all the way to the north pole and from the Sierras and Cascades all the way to the Appalachian mountains.