Fall can turn into winter quickly in Colorado and this morning many in the Denver area awoke to the first snow of the season. Denver’s average first snow is October 18th but last year the first flakes didn’t fly until November 17. The first snow of 2016 followed record setting warmth as Denver’s high temperature the day before reached 80°. This year the warmth before the snow fell was also pronounced.
The first snow of the season can often be heavy and wet. This was the case last year and is certainly today. The big flakes really added up to a significant first snow for the area as
across the Denver metro area snowfall amounts varied with the northern suburbs picking up over a half a foot with lesser amounts across southern locations. If you spent time clearing the car or possibly shoveling a deck today you know just how wet today’s snow was. This may sound strange because snow is frozen water but all snow storms are not created equal.
Snow to Liquid Equivalent:
When differentiating “wet snow” from “dry snow” we look to the snow to liquid equivalent ratio. The liquid equivalent of snow equals the amount of liquid is derived from the snow once it has melted. The ratio of snow depth to the liquid equivalent gives us a scale to categorize snowfall.
Automatic Precipitation Gauge
The “average” snow to liquid ratio is 10:1. Which means if 10 inches of snow fell and that snow was melted it would produce 1 inch of liquid precipitation. Today’s snowfall in Denver was about a 9:1 ratio and a bit on the wet and heavy side. By noon at Denver International Airport 2.5 inches of snow had fallen, yielding 0.28 inches of liquid. This roughly gives us the 9:1 ratio. Last year’s first snow in Denver of 1.7 inches yielded 0.22 inches of liquid. That ratio is closer to 8:1 ratio, for an even wetter snowfall.
Drier snow is less dense with plenty of air pockets within the snow crystals. Dry snow has a snow to liquid equivalent higher than the average of 10:1 and we can see ratios of 30:1 or more. With a 30:1 ratio it would take 30 inches of snow to yield 1 inch of water. The dry powdery consistency of this type of snow almost completely eliminates the hope for making snowballs as the snow does not stick together as well.
Meteorologist Mike Morrison