Thursday, 8 December 2016

Arctic Air Temperatures are Set to Hit 35 to 55 F Above Average

Arctic Air Temperatures are Set to Hit 35 to 55 F Above Average by Thursday — Out of Season Sea Ice Melt Possible, Again

It looks like a triple whammy – a warm ocean, a warm atmosphere, and a wind pattern all working against the ice in the Arctic.” 

Unfortunately, Arctic sea ice extent growth has once again slowed this week…”
 — Zack Labe

Huge surface air temperature anomalies over the Arctic this working week… over 25C warmer than average in parts.”

6 December, 2016

This year, it’s a challenge to find a time when the Arctic Ocean has ever represented anything resembling normalcy. Record low sea ice extent values have occurred for more than 50 percent of days measured. And well above average temperatures have invaded the Arctic during winter, spring, and fall. With another huge wave of ridiculous warmth building up over eastern Siberia this week, the hits just keep on coming.

Major Warming Over Siberia, Chukchi and East Siberian Seas 

The present big warm air invasion has its origins in the Pacific Ocean. There, a large high pressure system over the Bering Sea is facing off with a strong low moving up across Kamchatka. Running between the two is a powerful south-to-north wind pattern.
(A major warm wind invasion of the Arctic on Thursday is originating in the subtropical Pacific. A ridge in the Jet Stream extending all the way to the North Pole is pulling this big bulge of warm air north. As a result, extreme temperature departures and out of season sea ice melt for the impacted zones are likely. Image source: Earth Nullschool.)

As we can see in the image above, the flood of warm air has its origin around the 30 north latitude line. It flows directly over hundreds of miles of ocean, at times reaching a storm-force intensity near 70 mph. As it crosses into Siberia, the wind slows down. But it inexorably continues north, ever north — driven on by a serious pulse of atmospheric steam. By early Thursday, the leading edge of this warm air outburst from the Pacific side will have crossed the Pole and led to a flushing of Central Arctic air out into the Barents Sea and North Atlantic (you can view an animation of the predicted warm air pulse here).

This strong northward flood of warmth from the Pacific is running up under an extreme high amplitude wave in the Jet Stream that is bellowing out into the Arctic Ocean through the Bering and Chukchi seas. At its peak northward extent, the big Jet Stream wave is predicted to look something like this. And it is this severe contortion in the upper level wind pattern that has enabled this most recent extreme warm wind event to occur.

This pattern is now in the process of injecting above-freezing air temperatures into Eastern Siberia. By tomorrow, the warm air mass will encounter the coastal regions of the Chukchi and East Siberian seas. There, it will push temperatures as high as 2.5 C  (37 F) over zones that typically see readings in the -20s to -30s (Celsius). As a result, temperatures will range between 20 and 30 C (35 to 55 F) or more above average for many locations.
(Climate Reanalyzer has added a new color — white — for tracking extreme departures in temperature. In the positive anomaly column, we find departures hitting 30 C, or 54 F, above average for regions of East Siberia and the local Arctic Ocean.)

To be clear, these temperatures are highly abnormal. If a similar temperature departure happened in Gaithersburg, Maryland on December 8, it would produce 80 to 100 degree (F) readings. Of course, this anomaly is not happening in Gaithersburg. Due to a global warming related process called polar amplification in which the poles are more sensitive to alterations in rising greenhouse gas levels (due to fossil fuel and related emissions), extreme temperature anomalies tend to occur at the poles as rates of relative warming are 2-3 times faster in those regions. And the factors that we observe associated with this new Arctic warm wind event — powerful south-to-north meridional air flows coupled with extreme high amplitude waves in the Jet Stream — are also evidence of a number of weird new atmospheric circulation patterns that can tend to pop up as polar amplification intensifies.
Warm Winds May Cause Unprecedented Back-to-Back Fall Sea Ice Melt
The Pacific side of the Arctic has already been gaining heat ahead of the oncoming warm wind event over the past few days. And what we have seen, as a result, is a pretty severe loss of ice in the Chukchi Sea during early December. To be very clear, Arctic sea ice should be advancing at this time of year. But what we see in the image below (provided by A-Team over at the Arctic Sea Ice Forum) is advance followed by retreat as the warm wind event starts to ramp up.
(Ice refreeze in the Chukchi advances until it is rolled back by the most recent onrush of warm air flowing in from the Pacific. Image provided by A-Team at Neven’s Arctic Sea Ice Forum.)

Of course, the retreat seen above has occurred before the main force of warm southerly winds — due to hit the Arctic Ocean region by tomorrow. So the risks for continued losses in the Chukchi extend for at least the next few days. Losses there could be offset by large enough gains elsewhere to continue an overall seasonal freeze trend. But so far, with abnormal warmth also periodically building in over the near-Svalbard region and with Hudson Bay refreeze continuing to lag, that does not appear to be happening.

Looking at the larger monitors, we also find that, as happened during October and November, the pace of overall sea ice growth has stalled. According to JAXA, over the past 4 days, sea ice extent has only grown by 50,000 square kilometers. During a typical similar four day period for this time of year, growth would tend to average around 400,000 to 500,000 square kilometers. And with values at current record low levels, the inertial impetus for ice growth would be higher. That is, unless the climate state of the Arctic has radically changed — which appears to be the case.
(According to JAXA, Arctic sea ice extent has again hit a plateau when it should be freezing — this time at around 10 million square kilometers. As sea ice follows that line, record lows are again deepening — hitting near 800,000 square kilometers below previous lows for the day in 2015. Considering the fact that another major warming event is building into the Arctic Ocean, this plateau could again tip into melt as happened during the middle of November. Image source: JAXA.)

During mid November, a period of unprecedented warming produced an almost unprecedented period of fall melt. A similar November melt occurred during 2013. But the amount of melt then was smaller. And that melt did not occur at a time when Arctic sea ice values were at new record lows — as they were throughout the entire month during 2016. Similarly, during October, abnormally warm conditions produced an odd re-freeze plateau similar to the one we are now experiencing.

Given current conditions, there’s a risk that we could see a December melt event following the November melt event. For the amount of heat hitting the Pacific side of the Arctic is predicted to fall far outside of normal temperature ranges. And, barring major refreeze on the Atlantic side, we are at a rather higher risk of seeing the present plateau in sea ice values carry on for a number of days.


Hat tip to John Allen
Hat tip to Neven (on sabbatical)
Hat tip to A-Team
Hat tip to Ryan in New England

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