My snow observations in Sitka, AK


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Posted by Graupel on May 01, 2003 at 02:54:15:

Hello.. I just came across this site and want to share my experiences with snow.. I LOVE to study it as a hobby and I go crazy when we have a snow storm ;)

A lot of the snowflakes that occur here in Sitka, Alaska are about 1-1/2 inches wide, and are composed of nothing but rimed needles and columns. However, each flake packs onto another and what has surprised me is that every "clump" or "patch" of snow that I pick up is different. Even at night time the shade, material, smell of the air (mostly due to different dew points and temperatures) can change the composition of it.

Another interesting thing I have noticed is that the rimed needles & columns can fall as wet snow, but then when the temperature falls below freezing and the skies clear.. the snow that was once wet turns into a powder-like snow that scatters into lots of pieces in your hand and sticks much easier to anything.. and it gets your hands really wet too!

A good way to tell the composition of snowflake layers is to scoop it off car windows. What I normally do is first get a plastic folder, scoop it off of my car window, and then look under a flashlight (if you point the flashlight at an angle you could possibly see a reflection off the snowflakes and make out the exact shape and compositions within the other flakes). Scooping it off with your hands usually does work, and I enjoy the different sensations that each combination of flakes can give when you pick it up (true powder snow that falls with little water content.. usually after a "siberian" arctic outbreak here with clear, COLD (14 degree overnight lows), and extremely DRY nights (below 10 dewpoints and 50 humidity).

After arctic outbreaks such as the ones described above, the flakes tend to have more shapes to them and fall to the ground in their purest form.

Another interesting type of precipitation I have noticed here is called graupel. It is like small baby hail pellets that can fall violently and can often be seen in wind bands. They are not "hail" as we usually think of them, but are actually often very small, "soft" hail pellets, sometimes even conical-shaped (I've seen them shaped like rubies or diamonds). Graupel usually occurs in unstable convective cells where updrafts pull in raw moisture, usually liquid, which "rimes" onto snowflakes falling into those super-cooled water droplets. It then falls to the ground as graupel, also called "soft hail, baby hail"

I can't wait till next winter.. because this winter we have only had two significant snow storms here (normally we have over 6 bringing a total of 40-50" of snow.. but this winter we have only had like 10" total in this region of Alaska.. and Alaska in general has seen a lack of snowfall). Hopefully this el niņo is going to disappear :)


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