How do some snowflakes get so large?

Large snowflakes fall during a heavy shower in Seattle on Nov. 3, 2017 (KOMO Photo)

Friday brought not only the rare sight of early November snow to Seattle, but a bit of a surreal sight of huge snowflakes falling in the city.

It was enough during a particularly heavy shower in Seattle area to bring some massive snowflakes that made it appear the city was in a life-sized snow globe. What gives?

The massive snowflake clusters are caused when temperatures are right near freezing. As the snow falls from the sky, but then encounters 33 or 34 degree weather, the snowflakes begin their melting process.

As they do so, they become coated with a thin layer of water which in this case acts a bit like glue. In the chaos of falling snowflakes, instead of them just harmlessly bouncing off each other, they begin to stick to each other.

If the wind is nearly calm, as it was here, it won't blow apart the clusters, leaving you with "snowflakes" that appeared to be as large as 1-2 inches in rough diameter.

So when you see the big flakes, it's a sign that your snow is just on the fringe of being rain instead. As the air temperatures vary a degree or two depending on the varying intensity of the particular shower, snowflakes can change size within the same event.

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