Coatings Of Snow Drag Temperatures
February 10, 2012, 6:04 PM
The National Weather Service in Sioux Falls has been tracking temperatures when snow is on the ground since at least 1940. That data helps us forecast after snow ends.
By February, the average high temperatures are just starting to climb. The 30-year normal is 30 degrees for the next few days. But when no snow was on the ground, our average temperature was around 42.
The winds helped keep us from even approaching that number Friday.
When you start adding snow into the calculations, the numbers don't move much from the average. That shows days with snow cover are much more common, and our typical day reflects that. More than six inches of snow drops the highs around 10 degrees.
The numbers get a little cooler at night. Light snow usually keeps us around normal and rarer lingering heavy snow cuts at least ten degrees off already cold numbers.
Arctic air and pre-existing snow work in concert making bitter temperatures last. The cold air keeps snow from melting and snow keeps the ground-level air from warming. It's a good thing we had last week's melt-off otherwise we'd easily bottom out in the teens below zero.
We won't be that cold Friday evening. Regardless, neither comes close to the record lows for Friday evening: 27 below in Aberdeen and 35 below in Sioux Falls.
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