How could Global Warming trigger a new Ice Age in North America similar to the Younger Dryas?

I think as the oceans warm up there will be more clouds and more rain. If the clouds were persistent enough it cools the land to where there might be more snow in the summer time. Once snow is on the ground and it sticks other snow can then stick to this snow. If this snow builds high enough year to year during the summers (or if enough snow comes down in the winter and spring and doesn't melt) or both then I could see how another ice age could actually happen for 1 or more years here in North America depending upon the situation.

For example, in San Francisco Bay area we have two winters. One in the winter time and a less cold winter in the Summer time caused by high and low Fog coming onshore. So, we sometimes call this the "June Glooms" even though it comes earlier and earlier each year it seems like sometimes by March or April some years now. So, for example, the weather here might be for weeks and weeks around 56 to 58 degrees high (even during the summers) with a night time low of 54 to 53 degrees which is what we are seeing right now sometimes for weeks with very little sun during the Spring and summers.

So, it's not hard for me to imagine snow coming down various places in the northern Hemisphere and snow coming down (especially in the mountains over 3000 feet in elevation. This snow then refrigerates the air and then the snow starts dropping lower and lower.

I could see this sort of thing happening in North America under super cloudy conditions that went on a very long time with no sun (or very little sun) hitting the earth. 

For example, it is not uncommon for the road up Mt. Shasta from Mt. Shasta City called Everitt Memorial highway often stays closed at 6900 feet all summer long because of the amount of snow that has fallen. I have experienced this many times over the years. But, it happens.

A couple of years ago in fact at only 4000 feet elevation it stayed 12 feet of snow until at least June before it melted off in July and August. So, this can happen too often over the years.