Posts Tagged ‘cold’

Why does the snow sparkle so?

Saturday, January 7th, 2017

Lately around here we’ve been blessed with decent snow cover. A nice change from the last two winters. Nice fresh show that stays fresh thanks to lack of warm surges. To add to the beautiful scene, the snow has had lots of sparkles of light reflecting off the surface from the bright moon or nearby lights (there’s plenty of time to see this with days still solstice short). Here’s a couple photos (click on them for larger versions).

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Why so sparkly lately?

The answer is not in the snow itself, but what happened to the snow after it fell. It is true that normal snow crystals can and do sparkle, but the really big sparkles we’ve seen take bigger crystals… in this case frost crystals that have formed on the snow over a few days. This sort of frost is called surface hoar, ie., hoarfrost that has formed on the surface of the snow. Check out the daytime photos (of the same snow in the upper photos) that show the detail. One clue is the small amount of frost on the alder twig in the second photo.

20170104_150625-reduced 20170104_150715-reduced Hoarfrost in general tends to form during light wind situations when there are cold surfaces and lots of water vapor to crystallize onto those surfaces. The most rapid frost formation occurs when there is a source of liquid water close by such as a stream or fog. Yes, we did have some fog in Haines over the last few days. Uncommon during cold weather at this time of year…because the calm winds which allowed the fog to form are uncommon during cold weather here. Note for backcountry travelers: New snow over surface hoar can create a weak layer in the snowpack and increase avalanche danger.

Alaska weather on a roller coaster

Tuesday, February 11th, 2014

Wind-blown dust in Haines and other places.

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Red flag wildfire danger for the Mat Valley.

Strong pressure gradient along coast.

Back into the freezer

The strong “January thaw” that pushed well into the interior and tied the all time January record for Alaska is being pushed toward the back of our memories by seasonal and colder weather. Boy, it feels colder after a long warm spell! Wind chills here in northern Southeast Alaska are bouncing down to 5 to 15F below zero (-20C to -26C) at times. (more…)

Two kinds of cold in Alaska

Friday, February 1st, 2013

Dry cold, wet cold?   no.

Winter cold and summer cold?  no. Bitterly cold vs extremely cold?  no. Calm vs windy cold? close.

All these would make good blog subjects, but what I’m thinking about today is domestic cold vs imported cold. Seriously.

I have a good recent example. (more…)

Why is it so cold in Glennallen?

Wednesday, December 19th, 2012

The question in the title came to me in an email, but for every email I get there are probably hundreds asking the same question in Glennallen. Sure, there are thousands more asking it about where they live, be it Fairbanks or Juneau or Orlando for that matter. But I want to look at what appears to be a unusually cold spot this winter, the capital of the Copper River Valley, population, after throwing in close neighbors Gulkana, Gakona, Copper Center, etc, of a 1,100 or so very tough Alaskans.

Let’s look at the weather depiction map from yesterday Morning, courtesy of the Alaska Aviation Weather Unit. A great example, as Gulkana (that’s where the weather station is located), labeled with its 4 letter code PAGK, was the colder than any station except Northway (PAOR)! It was 40 below (Fahrenheit or Celsius, take your pick), colder than Fairbanks at the time and most of the rest of those off the map to the north. Those around it are way warmer, with only Eureka (PAZK) being in the same ballpark. Talkeetna (PATK) and Anchorage (PANC) are not even below zero! Are not all these places in the Southcentral zone?

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The (literally freezing) cold Alaskan summer continues

Friday, June 29th, 2012

The cold, cloudy, wet weather has been with Alaskans since May, with a only a few short breaks here and there. Here’s a recent example from the usually warmish Copper River Basin: A rainy day Wednesday in Glennallen (wx data from close-by Gulkana–that’s where the airport and weather station are for the Glennallen area) with a high of only 48F (9C), then some clearing overnight allowing the temperature to drop to 29F (-2C), the coldest spot in the state Thursday morning. That’s right, below freezing in late June.  And it’s the 6th day in a row that the cold spot of the state has been at or below zero Celsius. (more…)

Cold Spring in Alaska

Saturday, May 12th, 2012

If you have been waiting to see some statistics on how our winter of 2011-2012 rated compared to climate history, or if you were hoping for a long range forecast (educated guess) for the summer of 2012, stay tuned, I am working on both. I’ve been preoccupied with getting the 2013 Alaska Weather Calendar printed and out to stores. That rush is easing and I hope to increase the blogging frequency at least to where it was before. If you would like an automatic email when a new article is posted, sign up for that service under “Subscribe to Posts” either on the menu items across the top of the page or on the right hand sidebar items.

Of course, I can’t really do a winter wrap-up or declare a winner in the Iditasnow until winter is a little more over, can I? Look at what has been happening around the state:

In the Arctic, no one expects anything like spring weather for some time to come. In fact, the weather there has been pretty average for this time of year: Temperatures in the 20s F (around -5C) with some wind, a little snow and blowing snow lately. However, just a few days ago it was below zero on the North Slope and Bering Strait area. After a very snowy winter in Kotzebue, the 27 inches (69 cm) of snow on the ground is holding steady with well below freezing temperatures.

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The plows are still needed in Shishmaref. Click on the image to see it full size.

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