|Olympia this morning at 9:30, five inches of snow and counting.|
It's been like being in a snow globe here in Olympia this weekend. Big fat snowflakes for hours and then many tiny ones and near-whiteout conditions. And lots of time to check Cliff Mass's weather blog where you can stay up to date on the latest predictions for what was referred to as "Snowmageddon" earlier this weekend. While we've been focused on accumulation amounts, road conditions, and school and business closures, we may have overlooked the clouds themselves and the snowflakes they have brought us.
Here was what was happening in my neighborhood this morning:
Really huge snowflakes. As you probably know, snowflakes do not fall from clouds composed of ice crystals--the high cirriform clouds. Ice crystals falling from these clouds usually evaporate or sublimate in the air before reaching the ground. We can observe this as "virga" or "fallstreaks."
The clouds that bring us snow are the same clouds that bring us rain--the lower cumulonimbus, nimbostratus, and sometimes altostratus clouds. In summer, much of our rain actually begins as snow then melts on the way down--usually when it falls below freezing level (about 12,000 feet). In winter, however, freezing level is much lower and falling snowflakes have a much better chance of staying frozen on their journey to the earth. The general rule of thumb is that snowflakes will survive 1,000 feet below freezing level. Thus, if freezing level is at 1,500 feet, snow level could be as low as 500 feet. For us to get snow in Olympia (all the way down to sea level) freezing level needs to be at most 1,000 feet.
Here is what Meteorology Today author C. Donald Ahrens says about big, fat flakes: "Snowflakes that fall through moist air that is slightly above freezing [our current conditions in Olympia] slowly melt as they descend. A thin film of water forms on the edge of the flakes, which acts like glue when other snowflakes come in contact with it. In this way, several flakes join to produce giant snowflakes often measuring several centimeters in diameter."
Meanwhile, take advantage of this "wet snow." It makes great snowpersons and snowballs, but it's stickiness makes for clumpy cross-country skiing. Yesterday, my husband and I took to the Chehalis-Western trail in our Nordic skis and had only two other beings for company on our five-mile jaunt.
|Signs of our Nordic companions: a lone cyclist (whom we saw) and a mammal (whom we did not) that was not a dog. I am thinking fox judging by the pad size and shape and the pairing of tracks.|
|Snow, it turns out, isn't a good medium for identifiable animal tracks, but is ideal for tracking an animal a long distance.|