Sitka Nature

Graupel is a type of snow that forms when snow flakes fall through parts of the atmosphere that have supercooled water droplets. Instead of maintaining the form of flat snow flakes and/or elongated snow crystals, the supercooled water condenses as a rime on the surface that results in a pellet shape. Superficially, graupel looks a bit like hail, and many people call it that, but hail is a solid ball of ice that forms in repeated freezing/thawing cycles as water/ice is subject to updrafts and downdrafts in thunderstorms. With a little extra attention, it’s not hard to identify graupel from its less solid feel and slightly fuzzy appearance.

In Sitka, graupel is a fairly common form of precipitation from at least late fall through spring. I remember as a kid noticing that it seemed to fall, sometimes quite heavily, and then shortly after, a more traditional snow would begin. At this point, I’m not sure how strong that relationship is, but it did hold this week. We had a fair amount of graupel Saturday, especially in the afternoon and evening, with snow developing later in the evening and falling through much of the night. Perhaps the conditions that prevail as a front moves through are conducive to graupel formation, with snow falling after the passage of the front.

Most of today’s photos were take on a trip to Salmon Lake. The exception is a picture of The Sisters at Sunrise.

[View with PicLens]

I had heard this year was going to be an El Nino year, which seems to correspond to relatively mild winters in Sitka, so it was interesting to see winter season getting started relatively early this year, with snow beginning to fall last week. In fact, there is an El Nino developing in equatorial Pacific Ocean, but apparently in the Pacific Northwest, at least, El Nino impacts tend to be strongest later in winter.

I had ibuttons I wanted to place for a project on temperature variation I’m working on, so I took a couple of hours to hike up Indian River. There was not too much snow in the woods, but in the openings it was at least a foot deep. Temperatures are supposed to rise into the 40s this week, so the snow may not last long, however.

It was pretty quiet overall, but I did hear some Ravens and Golden-crowned Kinglets. I also saw a couple of Brown Creepers and a Varied Thrush. Lots of deer tracks, but I did not see any deer.