A new day with new information. Here's an animation of Uni Bremen sea ice concentration maps from August 3rd-6th:
We see some more flash melting from the 5th to the 6th on the edge of the ice pack in the Beaufort Sea region, although technically I think this is more compaction than real melting. We also see some of the early flash melting flashing back, or 'unflashing', in the East Siberian Sea. It looks like that large swath of ice there has alsmost detached itself from the main ice pack.
On this animation of DMI sea level pressure maps we can see how the cyclone developed from the 3rd to the 6th. The purple in the centre of the storm shows how low sea level pressure was and still is (lowest I've seen in yesterday's reports was 963 mb):
The last National Weather Service discussion for Northern Alaska has this:
A 965 MB LOW ABOUT 800 NM NORTH OF CAPE LISBURNE... EXCEPTIONALLY DEEP...PARTICULARLY FOR THIS TIME OF YEAR...WILL JITTER AROUND CYCLONICALLY FOR THE NEXT 24 HOURS BEFORE BEGINNING TO WEAKEN AND MOVE OFF NORTHEAST. IT WILL LIKELY NOT EVER GET MUCH SOUTH OF 80N
Luckily the ECMWF weather forecast for the coming days has improved a bit:
The storm will still be big and pretty intense tomorrow, but will then start to lose strength. Just in time so that we can make out the balance in the weekend in a new ASI update.
I will be updating this post, so refresh the page every once in a while.
I realize I haven't been providing enough information on Arctic storms, or hurricanes, or Polar lows as the official term is (EDIT: this is not a Polar low, as it is too big and much too central in the Arctic. For now I'm sticking with 'Arctic storm' or low, or cyclone). Well, that's because I don't know much about the phenomenon myself! I'll give some more general info once it's time to analyse the effect of the storm. In the meantime here's this short YouTube video I came across:
The trend line on the DMI sea ice extent chart keeps plummeting (after a 282K drop yesterday, according to Larry Hamilton):
I don't know if this is a fluke or an artifact or if it's real. IJIS hasn't updated since yesterday, Cryosphere Today lags a bit, Arctic-ROOS maps haven't been updated... We'll know more in a couple of days.
IJIS has updated, big 188K drop:
Cryosphere Today has reported the sea ice area number for August 5th, a drop of 78K, second biggest for that date in the 2005-2012 period. Given the lag and the drops on the DMI and IJIS extent maps, I would expect some bigger drops in the next 2-3 days. Not that the 2012 trend line needs it, as it is well ahead of the other years:
And Cryosphere Today has updated the sea ice concentration map as well, some more big changes, with that patch of ice in the East Siberian Sea almost detached from the main ice pack:
This is what a NOAA Fact Sheet on the Future of Arctic Climate and Impacts has to say (hat-tip to Brooklyn Jim at Daily Kos):
Sea ice retreat contributes to Arctic cyclone generation
The Arctic is warming faster than the rest of the globe, due to the decrease in Arctic sea ice. With less sea ice cover, the ocean absorbes more heat from the sun during summer, increasing the temperature contrast between the warm ice-free ocean and cold ice surfaces in autumn. The large temperature contrast contributes to the generation of Arctic cyclones. In the late September 2010, Japanese Research Vessel Mirai observed the explosive generation of an Arctic cyclone, shown in Figure 6.
Scientists analyzing observations from the Mirai concluded that this is an invaluable example of the fact that sea ice retreat contributees to polar amplification of surface air temperature increase and that cyclone generation is important in the transfer of the excess heat from the ocean into the atmosphere.
This is not the end of September, so I don't know if we're talking about the same mechanism here (waters haven't started to release their heat to the atmosphere yet), but still a good find, as it is hard to find information on the subject of summer Arctic storms.
Commenter Artful Dodger found a nice satellite image via Wunderground:
Slightly bigger waves at the Barrow webcam than yesterday:
The storm is losing its strength. If you go to this Environment Canada web page and click the Preliminary (Canada coverage) maps one by one, you see the intensity go from 965 mb, 967 mb, 969 mb to 970 mb.