Over the next few days we are expecting a good chance for snow that will accumulate across our region. Forecasts that you may have seen have pushed totals near or over 6 inches by Sunday morning; however, when you look at raw model numbers they are showing a lot less.

So what gives? Why is there a discrepancy?

The answer is the “snow ratio.” What is a snow ratio? A snow ratio is the percentage of water to snow, and on a typical basis the rule of thumb is that 10 inches of snow equals 1 inches of liquid water. When the temperatures are warmer, our snow ratio goes down, which means 1 inch of liquid equivalent will stack up to less than 10 inches of snow. The colder the air is, the higher 1 inch of liquid equivalent will build up. With the cold air in place, and expected to be in place this weekend, our snow ratios will likely be higher and lead to more fluff as opposed to wet heavy snow. Not only do surface temperatures have to be cold, but so do upper level temperatures. With another arctic surge of air expected the next two days, our snow ratios could get as high as 20:1 (20 inches of snow to 1 inch of liquid water)!

We are not expecting 20 inches of snow, but anywhere between .25 and .5 inches of liquid equivalent is in the forecast. This means that a general 4 to 8 inches of snow is expected through Sunday morning with even a chance for localized areas to see a little more.

The positive side of the “fluff factor” being so high is that it will be easy to remove as it is lighter with less moisture. This is why we talk about heavy wet snow or light fluffy snow, it’s all because of the snow ratio which temperatures dictate.