February 4, 2015: The Feb. 1, 2015 blizzard was interesting in a lot of ways, one being how the nature of the snow changed. The snow started out as wet and heavy, meaning it had a higher water content, making it easier to “pack” for snowballs, but more difficult to shovel and move because of the extra water weighing it down. About halfway through the storm, the snow changed over to being more “light and fluffy”, or that grainy type of snow that can blow and drift easily. So what happened?
First, let’s start with this: warm air can hold much more moisture than cold air. This is why, in the summer, we deal with a lot more humidity or moisture in the air, versus the winter, when we feel the air dry out our skin, because there’s barely any moisture at all in the air and it sucks the moisture away from us.
In the winter, we have varying levels of cold all the time, so if cold air can’t hold much moisture, why do we keep getting snow? It’s because snow doesn’t need as much water to form versus raindrops; as a result, a fraction of an inch of liquid can go a long way. This is where we start talking about snow ratios, or how much liquid it takes to produce a certain mount of snow.
Comparing wet,heavy snow to dry, fluffy snow
With regards to the Feb. 1 blizzard, the air started out warmer, which kept the snow ratios lower, closer to 10:1. That means if we had 1″ of water, it would produce 10″ of snow. The wet and heavy snow fell for a while, until the blizzard pulled in colder air from the north. That sparked the transition toward lighter and fluffier snow. At that point, the snow ratios were closer to between 25:1 to 30:1. As you can see, the drier, colder air can produce a lot more snow with the same amount of water. At this point, the winds started really picking up, so the blizzard conditions set in since the lighter snow could cause whiteout conditions more easily. If we had more of the cold air earlier in the storm, we could have seen the snowfall amounts grow even higher.
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