While not as exciting as the massive 20" of snow in 24 hours captured in New Jersey during a December snowstorm, Dr. Dale Ireland in Silverdale did get some interesting time lapse video of Monday's intermittent snow showers.
This time lapse is a great illustration of how you can get temporary snow showers when the temperature is right around 34-35 degrees.
Sometimes heavy showers can bring along some cold air for the ride -- and in the winter, it can bring an unexpected snow. Let's say it's 40 degrees on the ground in Seattle, but it's 25 degrees at the base of a cloud sitting overhead.
If that clouds lets loose and sends down a heavy barrage of moisture, that initial burst of snow then rapidly melts into the warmer air. But melting snow requires energy, so that intense melting actually zaps heat energy from the air, effectively making the air colder and in some cases, cold enough to snow.
This effect is usually temporary, with temperatures then bouncing back up after the showers end -- and in this video, you can see how the snow rapidly melts as soon as the shower ends. Also, how far the temperature drops is dependent on the strength of the showers. So one heavy shower could bring the snow level down to the surface and dump a quick 1-2 inches of snow, and perhaps the next weaker shower just drops the temperature a little and it stays as rain.
Dry air also helps this process because if the air is drier near the surface, the evaporation process is more efficient.