Minor weekend snow, ‘Thaw Watch’ and 30s possible next week?

Welcome to the weekend!

It may finally be warm enough to get out and actually enjoy some of our December snow. Ice skaters, skiers, snowmobilers and ice fisherpeople delight.

Temps will still run a good 10 to 15 degrees below average this weekend, but outdoor conditions will be a lot more bearable than the bitter cold of the past week.

A minor clipper brings some light snow through Saturday, but totals around an inch will generally be enough to brush off your car with a glove or favorite snow brush.

And did I mention the chances for a thaw are looking better next week? With moderating temps, we may finally be able to get out and enjoy winter in Minnesota in the next week.

Weekend at a glance: Light snow Saturday, colder Sunday

Some light snow Saturday will total an inch (give or take a few tenths) in many locations around the metro. Sunday features a colder breeze as temps hover in the single digits above zero.

Here's a detailed look at the weekend forecast according to the National Oceanic and Atmospheric Administration's Global Forecast System model, which has had a pretty good track record lately.

Thaw watch: 30s next week?

Time to top off the washer fluid in your favorite ride?

The weather pattern favors a growing chance for a thaw next week. Temps above 30 could kick in on milder southerly breezes. The European Centre for Medium-Range Weather Forecasts model has been the most optimistic with next week's potential temp surge. We may crack the freezing code next week, followed by another arctic front next Friday.

Christmas preview: Not as Nordic?

The medium range forecast maps have been all over the place with temps surrounding Christmas. The latest version backs off on the bitterly cold air advertised earlier this week.

Here's the latest GFS run, which keeps temps in the chilly but tolerable teens Christmas Eve and Day.

The science of snowflakes

As you watch the snowflakes fall this weekend and winter, think about the magic that creates these beautiful unique crystals of ice, here's a good description of the science behind snowflakes from NOAA.

Q: How are snowflakes formed? 

A:  A snowflake begins to form when an extremely cold water droplet freezes onto a pollen or dust particle in the sky. This creates an ice crystal. As the ice crystal falls to the ground, water vapor freezes onto the primary crystal, building new crystals – the six arms of the snowflake.

That’s the short answer.

The more complex explanation is this:

These ice crystals that make up snowflakes are symmetrical (or patterned) because they reflect the internal order of the crystal’s water molecules as they arrange themselves in predetermined spaces (known as “crystallization”) to form a six-sided snowflake.

Ultimately, it is the temperature at which a crystal forms — and to a lesser extent the humidity of the air — that determines the basic shape of the ice crystal. Thus, we see long needle-like crystals at 23 degrees F and very flat plate-like crystals at 5 degrees F.

The intricate shape of a single arm of the snowflake is determined by the atmospheric conditions experienced by entire ice crystal as it falls. A crystal might begin to grow arms in one manner, and then minutes or even seconds later, slight changes in the surrounding temperature or humidity causes the crystal to grow in another way. Although the six-sided shape is always maintained, the ice crystal (and its six arms) may branch off in new directions. Because each arm experiences the same atmospheric conditions, the arms look identical.

Q: So, why are no two snowflakes exactly alike?

A: Well, that’s because individual snowflakes all follow slightly different paths from the sky to the ground —and thus encounter slightly different atmospheric conditions along the way. Therefore, they all tend to look unique, resembling everything from prisms and needles to the familiar lacy pattern.