Monday’s fat gentle flakes of snow were a delight, but they weren’t enough to count as an official snow.
That means Omaha is running late on measurable snow. On average, the first snow occurs by Nov. 13, according to the National Weather Service. “Normal” is based on the 30-year period from 1981 through 2010.
For an official snowfall to occur, .1 of an inch of snow must be recorded. In Omaha on Monday, a “trace” was recorded based on readings at Eppley Airfield, said Scott Dergan, meteorologist with the weather service.
Snow is hard to measure, he said, but the basic difference between a trace and .1 of snow is that you can see it but can’t measure it.
To measure snow, forecasters place a board outdoors to collect snow and then measure it with a ruler. If snowfall on a board or other flat surface is deemed unreliable, they’ll measure based on the amount of snow accumulated on the ground.
At Eppley on Monday, the measurement was taken by placing a ruler in the grass near a runway. The ground was used instead of a board because the wind tends to blow snow off a board there. The disadvantage of measuring in the grass is that the ground is still warm, so snow is likely to melt before it is measured.
The Eppley measurements are taken by a company hired by the Federal Aviation Administration.
Official measurements, such as snowfall and rain, must be taken and reported to the weather service every six hours. With snow, measurements are sometimes taken more often.
Source: National Weather Service