bluewave

I think some people are coming into each season thinking that it will be a continuation of the 2007-2012 mega dipole pattern. But outside July 2015, the summer Arctic pattern did a complete reversal following that 2012 record breaking summer. It was like the 2012 extremes of low sea ice extent and Greenland melt flipped a switch over to a new regime. Maybe some type of mini summer Arctic D-O event?

I agree. The coming cooldown across the CAB should keep 2017 behind the 2012 extent over the next the next 10 days. 2012 will probably run away from 2017 in early August when the steep 2012 drop occurred. With the exception of July 2015, a cooler polar vortex has dominated the Arctic summers from 2013-2017.

Yeah, and how much colder this summer is in Greenland compared to 2012. http://polarportal.dk/en/nyheder/arkiv/nyheder/bringing-harmonie-to-the-greenland-ice-sheet/ Martin Stendel, Polar Portal leader, agrees. “This year has been extremely unusual, with a snowy winter and then a cool period at the start of this month. It’s extremely important we get the surface mass balance right.” The period from the 27th June to the 5th July saw days with close to zero or even slightly positive SMB (a net gain in mass) as well as a record low temperature recorded at the DMI weather station at Summit -33.0 °C. This weather along with the snowfall in early June, and following from the heavy snow in the Autumn, has led to a relatively high surface mass balance for the time of year and an unusually bright and reflective ice sheet, as shown in the albedo anomaly map on the Polar Portal (and below). Professor Jason Box of GEUS explains “when we see cold snowy conditions like this in the summer time it brings melt to a halt. The fresh snow is bright and reflects sunlight whereas in normal years dark bare glacier ice is usually exposed at this time of year and so melt rates are strong. This is why we track the albedo through the year to see how much melt we can expect”. So far this summer there has been less melt than usual. As DMI weather forecaster Jesper Rosberg explains, “we have seen a persistent positive North Atlantic Oscillation this summer and the jet stream has been very far south of Greenland with very cold air over the ice sheet, so the precipitation falling this summer has mostly been snow, rather rain. ” The cold and snowy conditions have been hindering scientific fieldwork this summer. But there are still several weeks of the ablation season left and the weather for the rest of July and August will determine the surface mass balance of Greenland this year. As far as DMI scientists know this is the first time that the SMB of the Greenland ice sheet has been calculated with such a sophisticated model in near real-time and it’s all the more interesting since we have snowfall interfering with melt.

On JAXA and NSIDC extent we probably missed to our chance to beat 2012 with the stronger PV pattern from June into early July. It even fell a little behind last year in recent days.

Either natural variability or the early emergence of the CCSM4 summer pattern in response to climate change. The NH summer circulation since 2013 bears a strong similarity to the presentation below. https://ams.confex.com/ams/94Annual/webprogram/Paper235210.html

Interesting increase in NH snow cover for June compared to recent years. The highest in over a decade.

After record breaking -AO and KB block last fall, the PV has mostly been in charge. While we had some transient Arctic blocking episodes, but the PV quickly makes a return.

It's funny how the pattern reversed right after the paper was published. http://onlinelibrary.wiley.com/store/10.1029/2012GL053268/asset/grl29604.pdf;jsessionid=F7950891CB18B3DB5580C02EC912A4A1.f01t03?v=1&t=j4ppf2qo&s=29436c163ab48e25e8f4989445de41091a8d6ccd&systemMessage=Wiley+Online+Library+'Journal+Subscribe+%2F+Renew'+page+will+be+down+on+Wednesday+05th+July+starting+at+08.00+EDT+%2F+13.00+BST+%2F+17.30+IST+for+up+to+75+minutes+due+to+essential+maintenance. Thus we can say that a six year run of near one standard deviation negative excursions (2007–2012) is unique in the 63 year record. To further test the significance of the 2007–2012 AD patterns we randomly generated 10,000 time series, each with 63 points to match the observed time series and with a normal distribution without autocorrelation. For this simple calculation, the chance for having five consecutive values with a negative AD of magnitude greater than 1.0 standard deviation units in a sample size of 63 is rare, less than 1 in a 1000.

While the overall annual temperature trend is an unmistakable up, it would be interesting to know what changed after the 2012 summer. To get a 6 year historic stretch of dipole patterns during the summer and then a reversal is pretty extreme 500 mb behavior.

June officially continues the post 2012 pattern of a more active polar vortex and cooler temps.You can see the long range ensembles continuing this general pattern right into July.

You are right. That was probably the better example of Volume vs extent divergence. 2007 was the year of the mega dipole. Remarkable how a version of the summer pattern repeated much of the time until 2012 and then abruptly reversed.

It's interesting how big a difference the extents can vary with similar volume depending on weather conditions. We saw the divergence between 11 and 12 extents on similar volume due to the much more hostile weather pattern in 12.

JAXA looks like it's on target to finish very close to last year if there is an average 2007-2016 melt rate for the rest of the summer.

IMHO the 2005-2007 period pretty much reset the whole Arctic background state. Arctic amplification really took off at that time when the September avg extents started regularly falling below 6 million sq km on NSIDC. We didn't even need a 2012 record minimum the last few years to set the extreme Arctic warmth records.

We would need a solid dipole pattern to lock in to have a chance of challenging 2012. Otherwise, it's going to be another year that the 2012 record holds. Seems like the really extreme Arctic conditions for the most part since 2012 have been during the winters instead of the summers from 2007-2012.

If this cooler pattern continues, then it might not really matter if we know the exact volume for sure. 2012 and 2011 weren't all that different on volume in August and September. But the 2012 record warmth with the weather pattern made all the difference between the two extent finishes in September. This June is continuing the post 2012 stronger polar vortex pattern vs the 2007-2012 raging dipole regime. We would need a July 2015 rapid reversal to really accelerate the melt. But that kind of reversal isn't showing up in the longer range guidance as of yet. Even Greenland is enjoying a below average melt compared to recent years.

PIOMAS actually pulled back closer to the pack the last few weeks.

More uncertainty about the actual thickness this year due to the divergence between PIOMAS and CryoSat. NSIDC mentioned it in a recent discussion. Data from the European Space Agency’s CryoSat-2 satellite indicate that this winter’s ice cover may be only slightly thinner than that observed at this time of year for the past four years. However, an ice-ocean model at the University of Washington (PIOMAS) that incorporates observed weather conditions suggests the volume of ice in the Arctic is unusually low.

Coolest first half of June at Utqiaġvik (Barrow) since 1974, 4.5°F (2.5°C) below the 1981-2010 normal. You know the weather patterns are really out of whack when it's 36 on January 1st in Barrow and can only reach a high of 38 degrees during the first half of June. https://mobile.twitter.com/AlaskaWx/status/875793934043291648/photo/1#

Yeah, the flip occurred right around the record breaking March 2013 -3.185 AO. That's when the dominant blocking shifted from the Atlantic to Pacific sector. The +PDO recently set a record breaking 40 positive months in a row.Must be related to AGW, Arctic, tropics, Atlantic, Pacific ,and rossby wave linkages.

The -425 m PV is one of the strongest that we have seen in June. So yet another June post 2012 without the strong 2007-2012 dipole making an appearance.

I don't think that reaching technically ice free in September is the important benchmark to focus on. The key number appears to have been dropping below 6 million sq km on a regular basis around 2005 in September. That's when Arctic amplification really took off.

Month...Year...Station...Rank 3...2010...EWR...7...NYC...6...LGA...5...JFK...4...BDR...2...ISP...3 4...2010...EWR...1...NYC...1...LGA...1...JFK...1...BDR...2...ISP...2 5...2010...EWR...4...LGA...5...JFK....4...BDR...4...BDR...4...ISP...5 6...2010...EWR...2...NYC...4...LGA...2...JFK...1...BDR...2...ISP...1 7...2010...EWR...3...NYC...2...LGA...1...JFK...1...BDR...3...ISP...2 8...2010...EWR...10...LGA...8...BDR...10 9...2010...EWR...5...LGA...6...JFK...7...BDR...7...ISP...7 ............................................................................................... 4...2011...EWR...10 6...2011...EWR...9 7...2011...EWR...1...NYC...5...LGA...10...JFK...2...BDR...4...ISP...3 9...2011...EWR...7..LGA...10...BDR...4....ISP...4 11..2011..EWR..5...NYC...6...LGA...6...JFK...5...BDR...3...ISP...4 12..2011..EWR...5...NYC...5..LGA...5....JFK...7...BDR...3...ISP...6 ................................................................................................ 1...2012...BDR...8...ISP...7 2...2012...EWR...3...NYC...2...LGA...2...JFK...1...BDR...1...ISP...2 3...2012...EWR...1...NYC...2...LGA...1...JFK...1...BDR...1...ISP...2 4...2012...LGA....4...JFK...4...BDR...3...ISP....4 5...2012...EWR...7...JFK...3...BDR...3...ISP...3 7...2012...EWR...5...JFK...6...BDR...7...ISP...7 12..2012..EWR..10...LGA..8..JFK...10...BDR...7...ISP...5 ................................................................................................ 7...2013...EWR...5...NYC...8...LGA...3...JFK...3...BDR...1...ISP...2 ................................................................................................ 12..2014..BDR...10...ISP...9 ................................................................................................. 5...2015...EWR...2...NYC...2...LGA...3...JFK...2...BDR...2...ISP...3 8...2015...EWR...7....NYC...4...LGA...4...JFK...2...BDR...3...ISP...4 9...2015...EWR...3...NYC...1...LGA...2...JFK...1....BDR...1...ISP...1 11..2015..EWR...1...NYC...1...LGA...3...JFK...2...BDR...4...ISP...1 12..2015...EWR..1...NYC...1...LGA...1...JFK...1...BDR...1...ISP...1 ................................................................................................. 3...2016...EWR...3...NYC...4...LGA...3...JFK...3...BDR...3...ISP...2 7...2016...EWR...9...LGA...4...JFK....5...BDR...5...ISP...5 8...2016...EWR...2...NYC...3...LGA...1...JFK...1...BDR...1...ISP...2 9...2016...EWR...3...NYC...5...LGA...3...JFK...5...BDR...2...ISP...5 10..2016..BDR..9...ISP...8 11..2016..EWR..9...LGA...5...JFK...7...BDR...10 ............................................................................................... 1...2017...EWR...10...LGA...6...JFK...6...BDR...1...ISP...6 2...2017...EWR...1....NYC...2...LGA...1...JFK...1....BDR...2...ISP...3 4...2017...EWR...4...NYC...2...LGA...2....JFK...2...BDR....2...ISP...1 9...2017...EWR..10..LGA...8...JFK...7....BDR...8...ISP...4 10..2017..EWR...1..NYC..1....LGA...1....JFK...2...BDR..1...ISP...1 ..................................................................................................... 2...2018...EWR...2....NYC...1...LGA....2....JFK...3....BDR...3.....ISP....1 5...2018...EWR...6....NYC...6...LGA....2....JFK...5....BDR...4.....ISP....4 8...2018...EWR...5....NYC...9...LGA....2....JFK...5...BDR....2.....ISP....4 9..2018....EWR...7....LGA...6...JFK.....8....BDR..6...ISP.....3 ...................................................................................................... 4.....2019....EWR...10...NYC...8...LGA...10...JFK...10...BDR...9.....ISP...5 7.....2019....EWR...7.....NYC..10...LGA...3....JFK....4....BDR...3.....ISP...2 9.....2019....LGA...8 10...2019....EWR...9...ISP...#7 .................................................................................................................... 1....2020...EWR...9...NYC...9...LGA....7...JFK...6...BDR...3....ISP...6 2....2020...EWR...6...NYC...6...LGA....8...JFK...4...BDR...5....ISP...3 3....2020...EWR...7...NYC...8...LGA....5....JFK...5...BDR...3...ISP...5 6....2020...EWR..10..LGA...3...BDR...5.....ISP....5 7....2020...EWR...5...NYC...7...LGA...1.....JFK...4...BDR....1...ISP....4 8....2020...EWR...10..LGA...5...BDR...3...ISP....6 11..2020...EWR....4...NYC...1....LGA....1...JFK...4...BDR...5....ISP....4 ................................................................................................................. 3....2021...LGA.....9....JFK....10.....BDR....8 6….2021….EWR…..2…..NYC….6……LGA……5…..BDR….ISP…..6 8….2021….EWR…..2…..LGA…..6…..JFK……10…..BDR….3…..ISP….5 9…2021…..EWR…..4…..LGA…..7…..JFK……7……..BDR…..5….ISP….4 10..2021….EWR…..1…..NYC…..6…..LGA….3……..JFK……3….BDR…..3…..ISP….2 …………………………………………………………………………………………………………………. 7…..2022……EWR…..#2….LGA…..#6….JFK….#4…..BDR…#10….ISP….#7

Endless summer...