Sitka Nature

I was up relatively early this morning trying to decide whether to make my way up Verstovia or Indian River, when I saw a partial rainbow in front of Mt. Edgecumbe. The sun was still not showing above the mountains in town, which probably helped make the colors of the rainbow seem extra bright. I quickly made my way down to Totem Park for a better view.

It’s been quite warm (by Sitka standards) over the past few days. Thursday’s high temperature of 75F broke the former record high for the date of 68F, set in 1990. It was slightly cooler on Friday, and the high temperature of 70F recorded at the airport did not come particularly close to breaking the record of 77F set in 1964, though several other communities (including Port Alexander on South Baranof island) did set records for the day.

The forecast for Friday called for clouds developing in the afternoon with a chance of thundershowers. I watched for cumulus clouds developing as the day went on, and although a few did, they seemed to stall out or dissipate rather quickly. The one shown in the photograph at the top of this post had mostly been blown apart (or so it seemed) within 20 minutes of the time I took the picture.

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.

After 3 cold springs in a row, it’s been kind of refreshing to have this year’s warmth in late winter, and an early start to Spring. There’s still a decent chance of below freezing temperatures and/or snow to come in March and even into April, but I’m hoping there aren’t any more hard freezes, or the berry crop will probably be a bust. It is an El Nino year, so perhaps that will keep things a bit warmer than usual. I would like to take some time to look back at the springs in other El Nino years to see if there’s any consistent pattern.

The pictures in this entry were taken yesterday, but the blueberries started blooming around town at least a couple of weeks ago, and there were crocus blooming by 2 February.