The image above, supported by the table later on shows that in December ice has recovered in the central Arctic with open water found only on the margins, as is typical this time of year. The animation shows progression of ice extent from Dec. 1 to Dec. 22, 2019.
Most dramatic is Hudson Bay on the left filling in over these 3 weeks, from 445k km2 up to 1214k km2, 96% of maximum. At the top, Chukchi Sea also ices over, from 589k km2 to 933k km2, 97% of max. Above Chukchi is Bering Sea just starting with fast ice, and Okhotsk upper right growing ice as usual. The two places lagging behind in ice recovery are Bering Sea and Baffin Bay.
The graph below shows the ice extent growing during December compared to some other years and the 12 year average (2007 to 2018 inclusive).
Note that the NH ice extent 12 year average increases almost 2M km2 during December, up to 13.1M km2. MASIE 2019 shows a faster icing rate, starting 600k km2 lower than average and now down 200k km2, or 1.5%. MASIE and SII are tracking quite closely this month. By month end all years appear to be converging on the 12-year average.
|Region||2019356||Day 356 Average||2019-Ave.||2010356||2019-2010|
The table shows where the ice is distributed compared to average. Bering Sea and Baffin Bay have the only large deficits to average, while Kara and Barents Seas are in surplus.
Footnote: Interesting comments today by Dr. Judah Cohen at his blog regarding the Arctic fluctuations. Excerpts with my bolds.
I have said many times the first thing that you learn as a seasonal forecaster is humility and these are one of those times. What is humbling me at the moment is that I have expected a weakening of the stratospheric polar vortex (PV) based on fall Arctic predictors – extensive Siberian snow cover, more limited Arctic sea ice extent and a relatively warm Arctic. Following the PV weakening or disruption, severe winter weather would be more frequent at least regionally across the mid-latitudes of the Northern Hemisphere (NH). But to be honest it is hard to see from today’s viewpoint how this verifies. And as I have shared on Twitter the new operational GFS, the FV3, has been especially bullish on a strong PV.
The biggest challenge that I see right now is the center of low mid-tropospheric heights currently just north of Alaska and is expected to expand in breadth over the next two weeks enough so to fill the entire Arctic basin. This a fairly class pattern of low heights in the Arctic and high heights in the mid-latitudes resulting in a cold Arctic/warm continents pattern, all consistent with a positive AO. It seems a bit ironic (at least to me) that with the record low sea ice in the Chukchi-Bering seas this fall, the incredibly warm year Alaska just experienced both in part due to persistent ridging in the region, this same region is predicted to now experience an extended period of low heights and below normal temperatures. As an aside, this is something that I had a hard time anticipating even just a few weeks ago.
So, for now I remain steadfast in the winter forecast that based on high fall snow cover/low Arctic sea ice that they will in tandem perturb the PV. Given the westerly quasi-biennial oscillation (QBO) I expect a scenario somewhere between winter 2016/17 and winter 2017/18. Both of those winters were westerly QBO winters and the most significant disruption of the stratospheric PV took place in February.
Illustration by Eleanor Lutz shows Earth’s seasonal climate changes. If played in full screen, the four corners present views from top, bottom and sides.