Colder temperatures usually result in more snow per inch of water. Here’s why.
ST. LOUIS — St. Louis is bracing for nearly a foot of snow to fall on the city and surrounding areas this week. Residents can blame incoming arctic air for the increased snow accumulation.
Much of the region will be under a winter storm watch starting shortly after midnight Tuesday.
The 5 On Your Side Weather Impact Team expects snow amounts of 4 to 10 inches to fall on most of the region, with communities south of St. Louis getting even more. How much snow falls where depends both on precipitation totals and how “dry” the snow is.
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The differences between “dry” snow and “wet” snow are in the name: Drier, powdery snow contains less water per inch compared to wetter, more sticky snow.
Dry snow occurs when temperatures closer to the ground are below freezing, which stops snowflakes from partially melting before reaching the surface. The lack of “stickiness” in dry snow causes it to only build up on the ground, rather than on trees or power lines. Fallen dry snow is also much less densely packed than wet snow, making it easier to shovel, but more prone to blowing and drifting.
For example, in the graphic above, the St. Louis area’s typical snowfall metric is 1 inch of water equals 10 inches of snow. However, with the upcoming winter storm and dangerously cold temperatures, 1 inch of water will garner close to 20 inches of snow.
St. Louis is forecast to have around half an inch of precipitation on Tuesday through Wednesday, which is why 5 On Your Side meteorologists expect between 4 to 10 inches of dry snow to fall on the region.
