As announced in ASI 2016 update 5 a very large cyclone is raging in the Arctic, as we speak. According to Environment Canada the storm's current central pressure is 970 hPa, but it was 968 hPa 12 hours ago, which is probably the lowest it will go. I've combined the weather map with yesterday's Uni Bremen sea ice concentration map, for geographical orientation and the storm's position in relation to the ice pack:
There hasn't been a marked effect on the ice as of yet. On the Forum Wipneus reports a large drop of 170K in the Cryosphere Today sea ice area numbers he calculates. This is the third largest August daily drop in the last decade, but Wipneus explains it is partly due to flash melting in the Canadian Arctic Archipelago. A large drop in NSIDC SIE numbers of 122K is entirely due to the CAA, but it would be even larger if it weren't for ice in the Laptev Sea 'unflashing' into the view of the SSMIS satellite sensor aboard the DSMP F18 satellite.
I expect some more flashing tomorrow in the regions that are directly affected by the storm. Not only is there a lot of ice jutting out towards the East Siberian and Chukchi Seas, there is also a 'bite' developing towards the pole. It can clearly be seen on this animation of Uni Bremen SIC maps. Also note the movement in the last two frames, due to the storm. This movement will become more marked in the next 2-3 days:
But back to the storm. As explained in the ASI update, a pressure of 968 hPa isn't as low as the 963 hPa of the Great Arctic Cyclone of 2012 (GAC-2012), but it is very low nonetheless. It's difficult to classify the storm, especially as it is still ongoing, but soon after GAC-2012 a paper was published by Simmonds and Rudeva to ascertain the storm's ranking according to their methodology:
The plot shows that AS12 was at the tail of the distribution and, at 966.38 hPa, was the lowest in our record, beating the previous deepest (966.94 hPa) (for a storm at 06UTC 7 August 1995) by 0.56 hPa. The next lowest central pressure, 969.23 hPa, was associated with a cyclone at 06UTC 22 August 1991, followed by the fourth lowest storm central pressure in the earlier part of that month 00UTC 7 August 1991 (970.47 hPa).
Their central pressure of 966 hPa is 3 hPa higher than the one reported by Environment Canada while the storm was ongoing. If the same applies to this storm, a central pressure of 971 hPa means there have been at least four stronger Augusts storms in their 1979–2012 database. However, they do not look at central pressure only, but also at intensity, radius, depth and longevity.
The storm loses strength, but doesn't fade away completely. In fact, the forecast beyond these 6 days is showing a re-intensification of the storm. Below is an animation of the entire 11-day ECMWF forecast, as provided by the Tropical Tidbits website, which shows the cyclone's forecast central pressure:
The cyclone maintains a central pressure of around 980 hPa for a couple of days, but on day 7 and 8 it restrengthens with the help of a couple of fellow cyclones, after which it goes turbo boost to 959 hPa. I think it's unlikely things will play out like this, as forecasts beyond 5-6 days become very unreliable. Still, it may be an indication that this storm is planning on sticking around.
Which brings us to the two main questions. First: What will this do to the ice? Will it cause massive flash melting, greatly accelerating ice melt through wind, waves, churning and Ekman pumping? Will there be a large polynya near the North Pole? Or will the cyclone bring so much cold with it that a lot of the ice that drifts away from the core into the periphery manages to hold on until the real refreeze starts in September?
And second: Can this storm be labelled a Great Arctic Cyclone? What we're seeing now, is pretty intense, but maybe not all that Great compared to GAC-2012 and other large August storms. To paraphrase famous philosopher Karl Pilkington: It's not a Great Arctic Cyclone, it's an all right Arctic Cyclone. It's the All Right Arctic Cyclone of 2016. ;-)
However, this may change if the storm lingers and re-intensifies next week. Stay tuned.