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Far-flung Barrow warmer than usual. What's behind Alaska heat wave?

Ben Anderson
Denali National Park photo

In Alaska’s Interior, it’s as cold as it ever was: Residents in the Interior community of Eagle saw temperatures dip as low as 40 below zero Monday morning, with other nearby areas measuring even chillier. But on Alaska’s North Slope, it’s been a pleasantly mild winter so far.

Well, relatively speaking. The mercury has still been hovering around and occasionally falling below zero. But from the start of September until Nov. 17, Barrow -- North America’s northernmost community -- had seen only six days fall below the normal average temperatures for the same time of year. By contrast, a whopping 67 days in recent months have seen above-average temperatures, including one day in late October that spiked to more than 20 degrees warmer than the norm.

The National Weather Service provided a handy graphic illustrating the unseasonable temperatures, attributing it in part to a lack of sea ice in the area. Climate Central was quick to latch onto that narrative, noting that when open water is present in place of sea ice, more solar radiation is absorbed by the ocean, warming the waters off of northern shores and consequently warming the shores themselves.

This, of course, could be tied into the record-low ice extent that befell the Arctic over this past summer, when the level of sea ice in the region shattered the previous low record set five years ago.

But there may be an issue with attributing Barrow’s warmer weather in recent weeks to a lack of sea ice, even though the basic premise is sound. According to Becky Legatt, a sea ice meteorologist at the NWS sea ice desk, the ice has already returned to Alaska’s two Arctic seas -- the Beaufort and the Chukchi -- and it’s been that way for a couple of weeks.

“They aren’t completely closed at this point, but about 70 to 90 percent of the water is covered (by ice),” Legatt said.

She said that it’s about the normal point in the year for ice to return to the region. And now the sea ice will grow even faster, since the sun has set in Barrow for the winter and won’t return until January, thanks to the town’s far northern location.

“Year to year, things vary as you transition and you lose the sunlight up there, (and) you see a dramatic increase in ice,” Lagatt said. “It’s like having a pot of water sitting outside -- if the sun hits it during the day it’ll warm up a little during the day and cool off at night. But in the winter it’s more like having the pot of water in a closet (outdoors), and it just continually cools.”

Lagatt added that the concentration of sea ice offshore in Barrow was a little lower than usual, though what impact that would have on air temperatures is difficult to figure. She said open water can be a little warmer, having a small warming effect on weather systems.

Barrow may already be seeing the effects of that long sunset, too. On Monday afternoon, the community hovered around 7 below, according to Dan Hancock, a meteorologist with the NWS in Fairbanks. The low for Monday was a goosebump-inducing 15 below. It remained chilly on Tuesday afternoon, at 8 below.

Hancock said the recent warmer temperatures in Barrow are likely being caused by the Arctic’s air mass, which is generally warmer than the oft-frigid Interior Alaska. And that warmer air may have an even more southerly origin.

“A slight but significant feed of warmer air -- and this blows clockwise -- is coming up from the Bering Sea, passing over eastern Russia, then into the Arctic Ocean (and) then over the Arctic Coast,” Hancock said.

That warm air usually gets filtered out by the Brooks Range in northern Alaska, contributing to those especially cold temps recently in the Interior. He added that eastern Russia has also been seeing higher than average temperatures, which could explain why that air that ends up in the Arctic has been a little warmer than usual.

But where’s that warmer air coming from? It could have an origin even farther south. An expected El Nino -- a warming of Pacific Waters near the equator -- never arrived this year. Neither did El Nino’s cooler-weather cousin, La Nina. Instead, this winter’s weather pattern could be one much harder to nail down, what’s known as a “La Nada,” sitting somewhere between the two.

The National Oceanic and Atmospheric Administration predicted last month that areas north of the Brooks Range in far northern Alaska could see continued warm temperatures. It hasn’t just been the last couple of months that Barrow’s been warmer than normal, either. The area has been seeing above-average temperatures since June.

Contact Ben Anderson at ben(at)alaskadispatch.com