Very interesting links, Laughing Muse.  But I think you are just gloating because your feet are dry and mine aren’t!! ( Kidding you )!

Thanks for the links- snowflakes are perpetually fascinating.  I hope we get some here for Christmas, but it doesn’t look good…

I’m no physicist, but after reading

The intricate shape of a single arm is determined by the ever-changing conditions experienced by the crystal as it falls.  Because each arm experiences the same conditions, however, the arms tend to look alike.

from the link above, my memory was jogged, and I found more info in Phillip Ball’s great book “H2O- a Biography of Water”.  He says that this isn’t the whole story:

A continuing mystery about dendritic snowflakes is why all six of their branches seem to be more or less identical.  The theory of dendritic growth explains why the side branches will develop at certain angles, but it contains no guarantee that they will all appear at equivalent places on different branches, or will grow to the same dimensions; indeed, these branching events are expected to happen at random.  Yet snowflakes can present astonishing examples of coordination, as if each branch knows what the other is doing.  One hypothesis is that vibrations of the crystal lattice bounce back and forth through the crystal like standing waves in an organ pipe, providing a degree of coordination and communication in the growth process.  Another is that the apparent similarity of the arms is illusory, a result of the spacial constraints imposed because all the branches grow close together at more or less the same rate.  But for the present, the secret of the snowflakes endures.

Coordination because of vibrations bouncing around the crystal lattice- it doesn’t get cooler than that.