Yeah I've noticed this and this is also true of rain showers. As for snow flakes sizes... I remember the final day that it snowed here last winter, one evening finishing work, we were very lucky and got an absolute pasting >10cm - of course didn't last long most had gone by the morning as a warm sector arrived overnight and thus winter ended. I digress, the biggest flakes I had ever ever seen. They were immense, everyone at work just stopped and looked outside in awe.