This is a good question. There are two main reasons.
First of all, snow is hard for radars to detect. The snowflakes do not reflect the radars energy as efficiently as rain or hail. This is even more so when the snow falls through very cold air and is a dry snow.
More importantly, where you are located in Somerset County, you are in the middle of three surrounding Doppler radars. These radars shoot their energy at a slight angle. By the time the beam gets to your area, it is quite high in the sky. Often snow falls from lower clouds which can be below this beam of energy.
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