Just in case we see a little snow before winter comes to an end, here is the short story of how snowflakes form. As you likely know, snowflakes form when below freezing water droplets freeze onto a dust particle or pollen in the air. As the ice crystal falls to the ground, water vapor freezes onto it's surface, building new crystals, which become the six arms of the snowflake.
Click on this link from NOAA to read more about what makes each snowflake unique:
So far this winter, PDX has only received a trace of snow, however four days have recorded snow in hourly observations. The so called "normal" snowfall for a season is 7.5 inches. Keep in mind Portland's snowfall is very irregular and may consist of no snow for several seasons or a foot deep snowstorm that cripples the city for a week! The latest in the season PDX has reported snow was a trace on March 28th back in 2008.
KGW Meteorologist Rod Hill