Interesting winter patterns in svaLbard. Causes? (climate, warmest, ice, records)

[wawa1992]

For a tundra climate (well any climate), svaLbard has odd winter patterns. The average high is 14 F / -10 C and low 3 F / -16 C in the coldest month (March). March is a bit odd as a coldest month, but relatively normal this far north (78 N). I've been examining the weather patterns on WeatherSpark (records for Longyearbyen, svaLbard since Sept. 29, 1975), and found:

1) Most winters have multiple thaw periods (avg high is below 20 F from Dec. 3 - Apr. 19, so we'll use Jan - Mar is core "winter). A "thaw period" in my definition is multiple days with a high above 32 F / 0 C. Sometimes, the thaw temperatures

2) Winters are all over the place. Any month from November to April can be coldest (and by quite a shot). It's actually not uncommon for April (which has 14-24 hours of daylight per day) to be coldest. In fact, May 2014 averaged colder than February 2014. October 2005 was warmer than January 2006.

Average monthly highs during winter can be anywhere from below 0 F / -18 C to above 32 F / 0 C. These are average monthly highs. In other words, it's possible for a winter month to be warmer than an average May, and actually has happened several times. Mean yearly high is about 26 F / -3 C.

So there are winter months that resemble summer more than winter (in temperature).

3) Some winters are cold during part of it, and warm during another part.

4) Summers show little of the wild variation winters do. Most years only top out at around 55 F / 13 C despite a warmest month high of 48 F / 9 C. It's actually typical for there to be no air frosts for 2-3 months, with temperatures unceasingly in that 33-55 F range.

For these reasons, svaLbard is one of the most interesting climates to study for me.

[B87]

Svalbard

[EverBlack]

It's because of the combination of the Gulf Stream (I think) and the northerly latitude. Everywhere at that latitude is like that (April can be the coldest).

[Jakobsli]

In earlier times, just a few decades ago, most of the sea around Svalbard would be ice covered in winter. Not any more. Some of the recent winters, not only the sea, but also the main Svalbard fjords have been ice-free. Thus, the relative warmth of the sea can warm the air, so winters are generally much milder than some decades ago.
It might seem strange that a place at 78 N, in the high Arctic, actually have 2-3 months with no (overnight) air frost at all. The reason is proably a combination of ice free sea keeping the air from getting too cold, and the midnight sun /24 hr sun from late April to late summer. However, summer weather is very often cloudy/ foggy, with frequent light rain /drizzle - even if the total rain / precipitation is very low on Svalbard, around 200 mm /year.

The warmer sea and temperatures at Svalbard has allowed more southern species of fish and shellfish to establish in the area. The "normal" cod is invading the area, threatening to replacing the Arctic cod. Even Mackerel, earlier not very common north of the North Sea, is now closing in on the sea around Svalbard (and Jan Mayen).

[wawa1992]

*Sometimes, the thaw temperatures reach well into the 40s F (4-10C)

Just realized my mistake in the original post.

[wawa1992]

svaLbard had a ground frost September 2nd (32 F / 0 C) for the first time since June 19th per WeatherSpark.

[Jakobsli]

Yes, there was air frost on September 2nd with minimum -0.1C. This is at Svalbard Airport / Longyearbyen.
Last frost before that was June 19nd with -0.2C.
So that's 74 frost-free days.

Detailed weather statistics for Longyearbyen (Svalbard)

Warmest high this summer was 12.2C. Coldest low last winter was -20C.